Citation
Proceedings of the ... annual meeting of the Florida State Horticultural Society

Material Information

Title:
Proceedings of the ... annual meeting of the Florida State Horticultural Society
Uniform Title:
Proceedings of the ... annual meeting of the Florida State Horticultural Society (1892)
Cover title:
Transactions of the Florida State Horticultural Society for ..
Cover title:
Proceedings of the Florida State Horticultural Society for ..
Creator:
Florida State Horticultural Society -- Meeting
Place of Publication:
Florida?
Publisher:
The Society
Publication Date:
Frequency:
Annual
regular
Language:
English
Physical Description:
59 v. : ill., ports. ; 23 cm.

Subjects

Subjects / Keywords:
Gardening -- Societies, etc ( lcsh )
Gardening -- Florida ( lcsh )
Genre:
serial ( sobekcm )
conference publication ( marcgt )

Notes

Dates or Sequential Designation:
5th (May 3rd, 4th, and 5th, 1892)-63rd (Oct. 31, Nov. 1 and 2, 1950).
Numbering Peculiarities:
Proceedings for the first four meetings not published.
General Note:
Title from cover.
Funding:
Florida Historical Agriculture and Rural Life

Record Information

Source Institution:
Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location:
Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management:
The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. This item may be protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact Digital Services (UFDC@uflib.ufl.edu) with any additional information they can provide.
Resource Identifier:
18435967 ( OCLC )
ca 09001702 ( LCCN )

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Full Text




PROCEEDINGS


of the.

FLORIDA STATE HORTICULTURAL
SOCIETY

for

1950

























































ROBINSONS
ORLANDO - APOPKA - TALLAHASSEE








PROCEEDINGS


of the


Sil~x*&h1d


4mwrdMeediotf


of the


1 FLORIDA STATE
HORTICULTURAL SOCIETY

held at

WINTER HAVEN, FLORIDA
October 31, November 1 and 2


1950


Published by The Society








FLORIDA STATE HORTICULTURAL SOCIETY, 1950


FLORIDA STATE

HORTICULTURAL SOCIETY


(t//I /0 1950


PRESIDENT
LEo H. WILSON Bradenton


CITRUS' SECTION KINCSWOOD SPROTT
Vice-President
Lake Wales

VEGETABLE SECTION
DR. A. H. EDDINS
Vice-President
Hastings


KROME MEMORIAL INSTITUTE
COL. W. R. GRovE
Vice-President
Laurel

ORNAMENTAL SECTION
ERDMAN WEST Vice-President
Gainesville


PROCESSING SECTION
DR. F. W. WENZEL
Vice-President
Lake Alfred

SECRETARY
DR. ERNEST L. SPENCER, Bradenton


EDITING SECRETARY W. L. TAIT, Winter Haven


TREASURER
LEM P. WOODS, Tampa


ASSISTANT SECRETARIES DR. F. S. JAMISON, Gainesville RALPH P. THOMPSON, Winter Haven BERT LIvINGSTON, Tampa


EXECUTIVE COMMITTEE DR. J. R. BECKENBACH, Chairman, Bradenton GEORGE H. COOPER, Princeton
R. S. EDSALL, Vero Beach E. V. FAmCLOTH, West Palm Beach
DR. F. E. GARDNER, Orlando FRANK L. HOLLAND, Winter Haven
H. A. THUrLBERY, Lake Wales








FLORIDA STATE HORTICULTURAL SOCIETY, 1950


FLORIDA STATE

HORTICULTURAL SOCIETY



C//zce4.1 ja4 1951


PRESIDENT
G. DEXTER SLOAN Tampa


CITRUS SECTION WILLIAM W. LAWLESS Vice-President
Winter Haven

VEGETABLE SECTION
NV. U. MOUNTS Vice-President
West Palm Beach


KROME MEMORIAL INSTITUTE
MARGARET J. MUSTARD
Vice-President
Coral Gables

ORNAMENTAL SECTION
EDWIN A. MENNINCER
Vice-President
Stuart


PROCESSING SECTION THEODORE J. KEv Vice-President
Winter Haven


SECRETARY
DR. ERNEST L. SPENCER, Bradenton


EDITING SECRETARY W. L. TAIT, Winter Haven


TREASURER
LEM P. WooDs, Tampa


ASSISTANT SECRETARIES DR. F. S. JAIISON, Gainesville RALPH P. THOMPSON, Winter Haven


EXECUTIVE COMMITTEE KINGSWOOD SPROTT, Chairman, Lake Wales FRANK L. HOLLAND, Winter Haven
R. S. EDSALL, Vero Beach DR. RALPH L. MILLER, Plymouth
E. V. FAIRCLOTH, West Palm Beach WILLARD D. MILLER, Ruskin
1I. A. THULLBERY, Lake Wales







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


CONSTITUTION


Article 1. This organization shall be known as the Florida State Horticultural Society, and its object shall be the advancement of Horticulture.
Article 2. Any person or firm may become an annual member of the Society by subscribing to the Constitution and paying four dollars. Any person or firm may become a perennial Member of the Society by subscribing to the Constitution and paying the annual dues for five or more years in advance. Any person or firm may become an annual susstaining member of the Society by subscribing to the Constitution and paying ten dollars. Any person may become a life member of the Society by subscribing to the Constitution and paying one hundred dollars. Any person or firm may become a patron of the Society by subscribing to the Constitution and paying one hundred dollars.

Article 3. Its officers shall consist of a President, one Vice President for each section, Secretary, Treasurer, Assistant Secretaries, and Executive Committee of seven, who shall be elected by ballot at each annual meeting. These officers shall take their positions immediately following their election. The duties of the Assistant Secretaries shall be outlined and supervised by the Executive Committee.
Article 4. The regular annual meeting of this Society shall be held on the second Tuesday in April, except when ordered by the Executive Committee.

Article 5. The duties of the President, Vice Presidents, Secretary and Treasurer shall be such as usually devolve on these officers. The President, Secretary and Treasurer shall be exofficio members of the Executive Committee.


Article 6. The Executive Committee shall have authority to act for the Society between annual meetings.
Article 7. The Constitution may be amended by a vote of two-thirds of the members present.
Article 8. A section of the annual program of the Society shall be devoted to the discussion of sub-tropical fruits, exclusive of the commonly grown varieties of citrus fruits. This section shall be known as the Kronw Memorial Institute. It shall be presided over by a fourth vice president who shall be elected by ballot at each annual meeting of the members in attendance at the Institute. The fourth vice president shall be an ex-off icio member of the Executive Committee.
Article 9. The Executive Committee may, at its discretion and on the basis of merit, nominate not to exceed five persons in any one year, for Honorary Membership in the Society. Honorary members . shall enjoy all privileges of the Society.
Article 10. A section of the annual program of the Society shall be devoted to the discussion of vegetables and other truck crops. This section shall be known as the Vegetable Section of the Florida State Horticultural Society. It shall be presided over by a Vice President, who shall be elected at each annual'meeting of the Society by the members in attendance at the Session. The Vice President shall be an ex-officio member of the Executive Committee.
Article 11. A section of the annual program of the Society shall be devoted to the discussion of ornamentals. This section shall be known as the Ornamental Section of the Florida State Horticultural Society. It shall be presided over by a Vice President, who shall be elected at








FLORIDA STATE HORTICULTURAL SOCIETY, 1950


section shall be known as the Processing Section of the Florida State Horticultural Society. It shall be presided over by a Vice President, who shall be elected at each annual meeting of the Society by the members in attendance at the Session. The Vice President shall be an ex-officio member of the Executive Committee.


each annual meeting of the Society by the members in attendance at the Session. The Vice President shall be an ex-officio member of the Executive Committee.

Article 12. A section of the annual program of the Society shall be devoted to the discussion of processing. This


BY-LAWS


4. All patron and lif e membership dues and all donations, unless otherwise specified by donor, shall be invested by the Treasurer in United States Government bonds. The earnings from these bonds shall be left as accrued values or reinvested in United States Government bonds of a guaranteed periodical value unless it is ordered by the Executive Committee or the Society that such earnings can be made available for operating expense. Receipts from perennial membership dues shall be placed on deposit at interest by the Treasurer. Only three dollars ($3.00) from each perennial membership fee shall be available during any calendar year for payment of operating expenses of the Society.


1. The Society year shall be coextensive with the calendar year, and the annual dues of members shall be four dollars.

2. All bills authorized by the Society or its Executive Committee, for its legitimate expenses, shall be paid by the Secretary's draft on the Treasurer, O.K'd by the President.

3. The meetings of the Society shall be devoted only to Horticultural topics, f rom scientific and practical standpoints, and the presiding officer shall rule out of order all motions, resolutions and discussions tending to commit the Society to partisan politics or mercantile ventures.







FLORIDA STATE HORTICULTURAL SOCIETY, 1950

AWARD OF HONORARY MEMBERSHIPS
FOR MERITORIOUS SERVICE To FLORIDA AGRICULTURE


MR.JAMES HARDIN PETERSON of Lakeland, Fla., born in Batesburg, South Carolina' February 11, 1894; graduate of Lakeland High School and of the College of Law of the University ofFlorida, receiving LL.B. degree; Doctor of Humanities, Fla. Southern College; admitted to the Bar in 1914; in his early practice, specialized in Municipal Law. He served several terms as Chairman of the Legislative Committee of the Florida League of Municipalities; special counsel for the Department of Agriculture, State of Florida; served in the Navy during World War 1. He was elected to the Congress on November 8, 1932; reelected continuously up to and including the present Congress; voluntarily retiring on January 1, 1951.
During his happy and productive representation of Florida in the Congress, Mr. Peterson has developed, and shown repeatedly, not only a keen interest in horticulture and other important interests, but a profound knowledge of them. This knowledge, coupled with his earnest desire to be of worthwhile public service, has been a tremendous profit to horticulture on many occasions. He has been an active citrus grower in Florida for many years. Known widely as the outstanding committee worker in the Congress, his work as a Member and Chairman of the Public Lands Committee has meant much to this country in dealing with public lands and natural resources. Mr. Peterson has served horticulture and other interests of Florida with real distinction.

DR. AVERY S. HOYT was born in San Diego, California, on September 16, 1888. He was graduated from Pomona College, California, in 1910 with a BSA degree. Following his graduation he entered the employ of the California State


Department of Agriculture, and was assigned to plant quarantine enforcement activities. He occupied various positions of responsibility within that organization, and in 1928 he was appointed Director.
In 1931, he went to Washington to become Assistant Chief of the Plant Quarantine and Control Administration. In 1934, he was selected to serve as Assistant Chief of the newly created Bureau of Entomology and Plant Quarantine. By reason of meritorious service he was advanced to the position of Associate Chief in 1941. On April 12, 1950, he was made Chief of the Bureau of Entomology and Plant Quarantine to fill the vacancy brought about by the death of Dr. P. N. Annand.
Dr. Hoyt's contributions to the agriculture of the nation have been largely in the field of plant quarantine. His early experiences in California convinced him of the need for taking all possible action to protect the several states from insects and disease from abroad, particularly states like California, Texas, Florida, and others which are peculiarly exposed to invasion by reason of geographical locations and international travel and trade. Throughout his service as a federal official he has endeavored to provide this protection while adhering to a strict scientific basis for all of his official actions, in spite of pressure brought to bear from many sources.

DR. HAROLD MOWRY came to Florida in 1916 from Kansas and Colorado. During the ensuing thirty-four years his record of significant contributions to our horticultural industry has not only added millions of dollars to the income of our State, but through his zeal, his completely unselfish and devoted service, his







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


loyalty to high ideals, and his friendly and sincere manner, he has carved f or himself a place in the hearts of the members of this Society.
His numerous scientific contributions are widely recognized. With the Florida State Plant Board he contributed to the eradication of Citrus Canker and the Mediterranean Fruit Fly. With the Florida Agricultural Experiment Station his original research pointed the way to the important role of the minor elements in plant nutrition on the mineral soils of the State. He is an undisputed authority o I n the culture and botany of Florida's ornamental trees and shrubs, and of many of her f ruits. His caref ul experiments became the foundation on which our Tung industry developed. While with the Experiment Station, he was author of thirteen of its most widely read bulletins, and has written hundreds of arti-


cles for scientific and popular journals.
In addition, he has written thousands of letters to individuals, helping in the solution of their horticultural problems, not only in Florida, but all over the world.
He retired on January 31, 1950 as Director of the University of Florida Agricultural Experiment Station, to which position he advanced through the ranks from Assistant Horticulturist. As Director his ability resulted in the growth of his organization to a position where it is now one of the largest in the Nation, with a world-wide reputation for the high standards and productivity of its research.
With all this he has remained a modest man and a loyal friend. He is deserving of the highest honor that this Society can confer.









FLORIDA STATE HORTICULTURAL SOCIETY, 1950



LIST OF MEMBERS







HONORARY MEMBERS


Fairchild, Dr. David, Coconut Grove Haden, Mrs. Florence P., Coconut Grove Hastings, H. C., Atlanta, Georgia Henricksen, H. C., Eustis Holland, Spessard L., Bartow Hoyt, Dr. Avery S., Wasington, D. C. Hume, Dr. H. Harold, Gainesville


Lipsey, L. W., Blanton Mayo, Nathan, Tallahassee M owry, Dr. Harold, Gainesville Peterson, J. Hardin, Lakeland Robinson, T. Ralph, Terra Ceis Swingle, Dr. Wi. T., Washington, D. C.


PATRON MEMBERS


American Agricultural Chemical Company, Pierce American Fruit Growers, Inc., Maitland Angebilt Hotel, Orlando Armour Fertilizer WVorks, Jacksonville Buckeye Nurseries Chase & Company, Sanford Deerfield Groves, Wabasso Deering, Charles Exchange Supply Company, Tampa Exotic Gardens, Miami Florida Citrus Exchange, Tampa Florida East Coast Hotel Co., St. Augustine Florida Grower Publishing Co., Tampa The Fruitlands Co., Lake Alfred Gardner, F. C., Lake Alfred Glen St. Mtarys Nurseries Co., Glen St. Marys Guolt Fertilizer Co., Tampa


Hastings, H. G. Co., Atlanta, Georgia Hillsboro Hotel, Tampa Klemm, A. M. & Son, Winter Haven Lake Garfield Nurseries, Bartow Manatee Fruit Company, Palmetto Mills The Florist, Jacksonville Nocatee Fruit Co. Nocatee Oklawaha Nurseries Co., Inc., Lake Jemn Southern Crate Manufacturing Assn. Stead, Lindsay, Box 809, Ft. Pierce Thomas Advertising Service U. S. Phosphsoric Products, Division Tennessee Corp.,
61 N. Broadwvay, Newv York, N. Y.
U. S. Phsosphoric Products, Division Tennessee Corp.,
Box 8269, Tampa
Van Fleet Co., 'Winter Haven Wilson & Tonmer Fertilizer Co., Jacksonville


LIFE MEMBERS


Agricultural Experiment Station, Puerto Rico Albertson Public Library, Orlando Alleobrand, Alfred, Box 288, Frostproof Alderman, A. D., Bartow Andrews, C. Wi., John Crerar Library, Chicago, Illinois Barber, C. F., Macdlenny Bartlom, WV. Leonard, Florida Agricultural Supply Co.,
Orlando
Berger, Mrs. Ei. WV., Gainesville Bouls, Clarence G., Box 6, Ft. Meade Briugham, M. S., Micco Britt, John F., Ft. Pierce Brown, A. C., Gainesville Bullard, Henry F., Bullard & Sprott, Lake Wales Carnegie, Mrs. T. M., Fernandina Champlain, A. E., H 8, No. 1, Palmetto Chidester, D. D. 446 Painter Ave., Whittier, California Christiancy, Cornelius, Port Orange Clement, Waldo P., Georgiana Conner, Wayne E., New Smyrna Cook, R. F., Leesburg County Agent, Orange County, Orlando Crutehfield & Woolfolk, Pennsylvania Produce Bldg.,
Pittsburgh, Pennsylvania Dsunedin Public Library, Dunedin


Ellsworth, Wilma J. (Miss), fit. No. 1, Dade City Fairchild. Dr. David, Coconut Grove Fugazzi, John, Fugazzi Brothers, Clearwater Gifford, Dr. John, Coconut Grove Guest, Mrs. Amy, N. Ocean Blvd., Palm Beacs Haden, Mrs. Florence P., Coconut Grove Hakes, L. A., Box 771, Orlando Hastings, H. G., 16 W. Mitchell St., Atlanta, Georgia Henricksen, H, C., Box 1045, Eustis Hernandez, Pedro, 108 Cienfuegos, San Fernando, Cubat Hollin~gsworth, G. S., Arcadia Hume, H. Harold, Gainesville Iowa State College Library, Ames, Iowa Jacocks, A. J., Winter Haven Lassen, H. C., Garden Spring Terrace,
-Saratoga, California Lauman, G. N., Ithaca, N. Y. Leonard, George V., Hlastings Manatee Fruit Co., 1st National Bank Bldg., Tampa Martin, A. Vim., Box 86, Sebastian Mathews, E. L., Plymouth McCarty, B. K., Eldred McCarty, Mrs. C. T., Eldred Merritt, Dr. J. C., 297 Sherman St., St. Paul Minnesota Michael, A. B., Wabasso









FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Montgomery, Robert H. (Col.), Coconut Grove Montgomery, Mrs. Robert H., Coconut Grove Morrell, Albert, Orlando Mountain Lake Corporation, Lake Wales O'Byrne, Frank M., Lake Wales Obmner, C. J., West Palm Beach Olivebaumn, J. E., Clermont Pedersen, W. L., Winter Haven Penuock, Henry, Sr., Jupiter Phillips, Howard, Orlando Phipps, Jobn S., N. Ocean Blvd., Palm Beach Phipps, H. C., N. Ocean Blvd., Palm Beach Phipps, Howard, Delray Beach Pike, W. N., Blanton Plymooth Citrus Growers Asso., Plymouth Prosser, Lew, Plant City Ranlerson, J. Ed, Arcadia Reasoner, N. A., Bradenton Reid, W. C., Largo Rode, H., Sebring Ricketson, Mrs. M. C., "Grayfield," Fernandina Sample, J. W., Haines City


Sandlin, A. R., Leeshorg Schuman, Albert, Sebastian Sellards, Dr. E. H., State Geologist, Austin, Texas Sevil, Mrs. Sara L., Fort Myers Sloan, G. D., Box 1021, Tampa Stanton, F. W., Dock & Walnut Sts., Philadelphia,
Pennsylvania
Stead, Lindsay, Box 809, Ft. Pierce Stevens, Edmund, Verge Alta, Puerto Rico Stuart, L. E., Montemorelos, Mexico Taber, Mrs. George L., Glen St. Marys Taylor, J. S., Largo Thomas, Jefferson, Gainesville Todd, E. G., Avon Park Towns, Thomas R., Holguin, Cuba Trelease, Win., University of Illinois, Urbana, Illinois Trueman, Roy B., Trueman Fertilizer Company,
Jacksonville
Von Borowsky, Miss Lisa, Brooksville Wilson & Toomer Fertilizer Co., Box 4459, Jacksonville Wirt, E. L., Box 144, Babsou Park Yothers, W. W., 457 Boone St., Orlando


SUSTAINING MEMBERS


Adams Packing Assn., Inc., Box Drawer "B,"
Auburndale
Allen, Ruth Stuart, P. 0. Box 804 (Tropical
Gardening), Coral Gables
Asnerican Cyanamid Company, 30 Rockefeller Plaza,
New York 20, N. Y.
American Fruit Growers, Inc., Ft. Pierce Austin, Guy D., and Co., Miami 35 Babb, Herbert A., Gulf Fertilizer Co., Umatilla Barber, Bascom D., Wilson & Toomer Fertilizer Co.,
Box 685, Clearwater
Bellows, Dr. J. M., Hectnr Supply Co., Miami Bergstrom Trading Company, Inc., 233 Broadway,
New York 7, N. Y.
Bland, W. T., American Fruit Growers, Lake Jemn Brady, R. C., NACO Fertilizer Co., Titusville Brooks, J. R. Box 36, Homestead lBroward Grain and Supply Co., Inc., Ft. Lauderdale Browder, David, Box 310, Arcadia Bryan, L. T., Fosgate Growers Coop., Box 2673,
Orlando
Durpee, W. Atlee Co., Sanford Burrichter, A., Box 42, Homestead California Spray Chemical Co., Box 1231, Orlando Campbell, John W., Goulds Carleton, R. T., Plymouth Cartledge, Raymond H., Cartledge Fertilizer Co.,
Cottondale
Charles, Wilber G., Florence Citrus Growers Assn.,
Florence Villa
Chase, Randall, Box 291, Sanford Clask, Everett B., Associated Seed Growers, Inc.,
Walcaid Bldg., Bradenton Clark, John D., Waverly Clark, S. W., Agricultural Department, Texas Gulf
Sulphur Co., 1002 Second National Bank
Bldg., Houston 2, Texas Clinton Foods., Inc., Dunedin Conkling, W. Donald, Citrus Culture Corp., Mt. Dora Cooper, George H., Glade & Grove Supply Co., Box
198, Princeton


Cooper, R. K., Florence Foods Inc., Florence Villa Crum, H. M., International Minerals & Chemical Corp.,
908 Mortgage Guarantee Bldg., Atlanta 3, Ga. Dabney, B. G., Coronet Phosphate Co., Plant City Dancy, R. C., Jackson Grain Co., Cass & Ashley Sts.,
Tampa
DiGiorgin Fruit Corp., Winter Haven Dixie Lime Products Co., Box 578, Ocala Dolomite Products Inc., Box 578, Ocala Dozier, G. L., NACO Fertilizer Co., Box 232, McIntosh Doda, Andrea, Jr., A. Duda & Sons, Oviedo Duda, Ferdinand. A. Duda & Sons. Oviedo Dundee Citrus Growers Assns., Dundee Dye, Alfred M., Everglades Fertilizer Co., Box 821,
Ft. Lauderdale
Dye, John B., Jr., Everglades Fertilizer Co., Box 821,
Ft. Lauderdale
Edsall, R. S., 1828- 28th Ave., Vero Beach Faireloth, E. V., 2829 South Dixie, West Palns Beads Faircioth Truck-Tractor Co., 2829 Sooth Dixie, West
Palm Beach
Florida Agricultural Research Institute, Box 392,
Winter Haven
Florida Citrus Canners Coop., Lake Wales Florida Citrus Exchange, Box 2349, Tampa 1 Florida Citrus Production Credit Assn., Box 2111,
Orlando
Florida Dolomite Co., Pembroke Florida Fruit & Vegetable Assn., 29 Sooth Court St.,
Orlando
Florida Seed and Feed Co., Ocala Fortner, J. E., Citrus Culture Corp., Mt. Dora Fudge, Dr. B. RH., Wilson & Toomer Fertilizer Co.,
P. 0. Drawer 4459, Jacksonville Grant, A. J., 259 Scotland St., Dunedin Green, William F., Wilson & Toomer Fertilizer Co.,
P. 0. Drawer 4459, Jacksonville Greenwood Products Co., Graceville Growers Fertilizer Coop., Lake Alfred Hagadorn, D L., Jackson Grain Co., Cass & Ashley
Sts., Tampa









FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Hagar, Jack, Fosgate Growers Coop., Box 2672,
Orlando
Haines City Citrus Growers Assn., Haines City Haines City Heights, Inc., Haines City Hawkins, Howard, Box 410, St. Augustine Heller Brothers Packing Co., Winter Garden Henderson, Fred F., Winter Haven Hicks, W. B., Wilson & Toomer Fertilizer Co.,
P. 0. Drawer 4459, Jacksonville Hinson, Alvin H., Box 868, Plant City Holland, Frank L., 324 Ave. B., NE, Winter Haven Horton, W. D., Collins Feed & Supply Co., N. E. 94th
& FEC R'way, Miami 38
Howard, J. D., Howard Fertilizer Co., Orlando Howard, R. M., Howard Fertilizer Co., Orlando Howell, Morton, WVaverly Growers Coop., Waverly Hunt, D. A., Florida Citrus Canners Coop., Lake Wales Immokalee Growers, Inc., c/n J. T. Gaunt, Immokalee Jackson, R. D., Jackson Grain Co., Cass & Ashley Sts.,
Tampa
Jamison, J. R., Deerfield Groves Co., Wabasso Jones, R. S., Wilson & Toomer Fertilizer Co., P. 0.
Drawer 4459, Jacksonville jungle Gardens, Sarasota Kirne, C. D., Jr., Waverly Growers Coop., Waverly Kinnard, R. R., Gulf Fertilizer Co., Box 607, Homestead King, Battey, Naples
Kinsey, L. P., Box 878, Winter Haven Kirtley, A. G., Dundee Citrus Growers Assn., Box
1121, Winter Haven
Klee, W. H., NACO Fertilizer Co., Jacksonville 1 Klemm, A. M. & Son, Winter Haven Laird, Norman N., Waverly Growers Coop, Waverly Lake County Citrus Sales,, c/o Bruce Floyd, Leesburg Lee, C. S., Box 225, Oviedo Lesley, John T., Haines City Citrus Growers Assn.,
Haines City
Li,,s, E. W., Amer.ican. Fruit Gruwers, Inc., Fee Bldg.,
Ft. Pierce
Little, C. S., Superior Fertilizer Co., Odessa Lucas, Glen H., Peninsular Fertilizer Co., Box 2989,
Tampa 1
MacDonald, R. M., Chester Groves Co., City Point McLain, L. Rogers, Gulf Fertilizer Co., Box 2721,
Tampa 1
McLane, W. F., Lyons Fertilizer Co., Box 310, Tampa McSweeney, W. M., Gulf Fertilizer Co., Box 2721,
Tampa 1
Mares, G. F., Superior Fertilizer Co., 9141'a McBerry,
Tampa
Matheson, Hugh M., 418 S. W. 2nd Ave., Miami 36 Mathias, A. F., Superior Fertilizer Co., Box 183,
Lake Hamilton
Maughan, D. B., California Spray-Chemical Co.,
Orlando
Maxwell, Lewis, Jackson Grain Co., Cass & Ashley
Sts., Tampa
Maxcy L., Inc., Frostproof Mershon, Claud C., Fosgate Growers Coop., Box 2673,
Orlando
Messec, Morrel, Gulf Fertilizer Co., Box 687,
Bradenton
Michael, A. B., Deerfield Groves Co., Wahasso Mitchell, Edward C., Citrus Culture Corp., Mt. Dora Mount Dora Growers Coop., Mount Dora Oslo Citrus Growers Assn., Oslo Palm Harbor Citrus Growers Assn., Palm Harbor


Pasco Packing Co., Dade City Pedersen, W. C., Waverly Growers Coop., Waverly Perrin & Thompson, Inc., Box 1000, Winter Haven Pinellas Growers Assn., Clearwater Pinkerton, J. B., Chester Groves Co., City Point Plummer, Dr. J. IK., Tenn. Corp. Research Lab., 900
Roosevelt Hwy., College Park, Ca. Plymouth Citrus~ Growers Assn., Plymouth Prevatt, J. B., Lake Region Pkg. Assn., Tavares Price, R. C., Florida Agri. Supply Co., Box 658,
Jacksonville 1
Prior, Henry A., Domino Citrus Assn., Inc., Box 179,
Bradenton
Prine, R. H., Box 85, Terra Ceia Producers Supply, Inc., Palmetto Raoul, Loring, Box 871, Sarasota Reed, R. R., Gulf Fertilizer Co., P. 0. Box 2721,
Tampa
Richardson, D. K., 2664 - 19th St., Vero Beach Richardson, E. G., 235 S. Indian River Drive,
Ft. Pierce
Rickborn, J. H., Lyons Fertilizer Co., Box 310,
Tampa
Roess, M. J., Box 388, Jacksonville Rothwell, A. D., Superior Fertilizer Co., 1407
Hesperides, Tampa
Ruskin Vegetable Distributors, Ruskin Ryhumn, Alexander W., Box 977, Vero Beach Sachs, Ward H., Box 3588, Orlando Sample, James M., Lyons Fertilizer Co., Box 310,
Tampa
Sarasota jungle Nurseries, Sarasota Seidel, G. A., Box 7, Gotha Sheffield, J. R., Coronet Phosphate Co., 19 Rector St.,
New York 6, N. Y.
Shields, J. C., Domino Citrus Assn., Inc., Box 179,
Bradenton
Skinner, B. C., Dunedin Skinner, F. L., 379 Monroe St., Dunedin Sloan, G. Dexter, Superior Fertilizer Co., Box 1021,
Tampa
Slough Grove Co., Inc., Dade City Smith, F. M., Howard Fertilizer Co., Orlando Smith, Herbert A., Jr., 1019 Lancaster Drive, Orlando Snively, John A., Jr., Eloise Groves Assn., Winter
Haven
Snively, T. V., Box 10, Winter Haven South Florida Motor Co., Box 151, Sebring South Lake Apopka Citrus Growers Assn., Oakland Speights, J. A., Everglades Fertilizer Co., Box 821,
Fort Lauderdale
Spencer, T. C., Haines City Stewart Packing Coop., Box 324, Auburndale Swann, Tom B., Box 232, Winter Haven Tennessee Corp., Research Laboratories, 900 Roosevelt
Highway, College Park, Ga. Thomas, Wayne, Box 831, Plant City Thssllbery, C. C., Lake Region Pkg. Assn., Tavares Tilden, A. M., Box 797, Winter Haven Tilden, L. W., Winter Garden Tomelaine Groves, Winter Haven Tucket, Inc., Minneola Van Horn, M. C., Florida Agri. Supply Co., Box 658,
Jacksonville 1
Virginia-Carolina Chemical Corp., Orlando Walker, Eli C., Jr., Box 796, Vero Beach Ward's Nursery, Box 177, Avon Park









FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Waring, W. L., Jr., Lyons Fertilizer Co., Box 310,
Tampa
Waverly Fertilizer Works, Waverly Waverly Growers Coop., Waverly Wetumpka Fruit Co., Box N, Hastings Wheeler Fertilizer Co., Oviedo Whitfield, Charles S., Amherst Apts., Orlando Wilson. Homer A. Gulf Fertilizer Co., Box 746,
Ft. Pierce
Winter Park Land Company, 128 Park Ave. S.,
Winter Park
Wolfe, J. C., Lyons Fertilizer Co., Box 310, Tampa Wood, Wade W., Gulf Fertilizer Co., Box 684, DeLand


Woodlea Groves, Box 144, Tavares Woodruff, F. H. & Sons Inc., 695 Glenn St., S. W.,
Station A, Box 164, Atlanta, Ga.
Woods, Fred J., Gulf Fertilizer Co., Box 2721, Tampa I Woods, J. Albert, Wilson & Toomner Fertilizer Co.,
P. 0. Drawer 4459, Jacksonville
Woods, Lem P., Gulf Fertilizer Co., Box 2721,
Tampa 1
Wray, Floyd L., Box 1782, Flamingo Groves, Inc.,
Ft. Lauderdale
Yager, Alonzo, Waverly Growers Coop., Waverly Yandre, Thomas E., Farm & Home Machinery Inc.,
Box 8547, Orlando


ANNUAL

As of February 26, 1951


Abbey, 0. H., P. 0. Box 27, Ft. Lauderdale Abbott, Fred P., Room 105, Union Station,
Savannah, Ga.
Adams Packing Assn. Inc., Drawer B, Auburndale Alexander, J. F., Box 154, Bartow Alexander, Taylor R., Botany Dept. Univ. of Miami,
Miami
Allen, E. J., 2150 N. W. 17th Ave., Miami Allison, R. V., Everglades Exp. Sta., Box 87, Belle Glade American Cyanamid Co., 80 Rockefeller Plaza,
.New York 20, N. Y.
American Fruit Grower Publishing Co.,
106 Euclid Ave., Willoughby, Ohio
American Potash & Chemical Co., Atlanta, Ga. American Potash Institute, Am. Chemical Soc. Bldg.,
1155 - 16th St. N. W., Washington 6, D. C.
Andrews, W. R. E., 1505 Race St., Philadelphia 2, Pa. Angel, L. B., Haines City Appleton, Shelton, Box 2281, Lakeland Armour Fertilizer Works, P. 0. Box 599, Jacksonville Arzave, Genaro, P. Mier 828 Ote., Monterey,
N. L. Mexico
Atkins, C. D., Box 448, Rit. No. 1, Winter Haven Ayers, Ed L., County Agent, Palmetto Backus, F. E., Box 288, Frostproof Bailey, E. R., Sanibel Baker, A. L., Box 247, Lakeland Baldwin, Mrs. Porter, 808 Monroe Drive,
West Palm Beach
Ballentine, C. C., P. 0. Box 8751, Orlando Barber, B. D., Box 685, Clearwater Barcus, David F., Box 601, Ft. Pierce Barker, J. P., Box 1181, Winter Haven Barksdale, D. N., Box 2567, Mulberry Barnett, Joe P., d/o American Fruit Growers, Inc.,
Ft. Pierce
Barrus, Mrs. Edith, Tallahassee Bartz, Paul, 806 S. E., 12th, Ft. Lauderdale Baskin, J. L., 1280 Golden Lane, Orlando Bass, C. A., 82 N. W. 34th St., Miami Beardsley Farms, Clewiston Beckenbach, J. R., Asso. Director, Fla. Age. Exp.
Station, Gainesville
Beerhalter, A., lit. No. 8, Box 800, Ft. Pierce Beisel, C. G., Real Gold Citrus Products, Box 280,
Anaheim, California
Benitez, Lic, Jose, Edificio La Nacional, 311
Monterrey, N. L. Mexico


Bennett, Charles A., 1825 N. W. 2 1st, Miami 87 Berry, James, 882 "E" S. E., Winter Haven Bickner, Charles, P. 0. Box 1282, Bradenton Biebel, Joseph Ri., 812 No. 4 Rd., S. Miami 48 Biggins, Harry N., Box 58, Clearwater Bissett, Arthur M., Box 66, Winter Haven Bissett, Owen, 1340 Lake Mirror Drive, Winter Haven Blackmon, G. H., Agri. Exp. Sta., Gainesville Bodine, E. W., 50 W. 50th St., Shell Chemical,
New York, N. Y.
Boswell, Ralph, 206 E. Amelia St., Orlando Bourne, Dr. B. A., Box 6868, Clewiston Boyd, F. E., Box 120, Montgomery, Ala. Boyd, Thos. M., lit. No. 1, Box 408, Winter Haven Bradhury, Charles 0., lit. No. 2, Winter Haven Bragdon, K. E., Indian River City Bristow, J. J. R., juice Industries, Inc., Dunedin Brockway, E. K., Box 695, Clermont Brokaw, C. H., Minute Maid, Plymouth Brooks, A. N., Box 522, Lakeland Brooks, J. H., DiGiorgio Fruit Corp., Box 1852,
Ft. Fierce
Brown, C. H., Box 601, Ft. Pierce Brown, Glenn, Tavares Brown, M. R., Box 575, Winter Haven Brown, R. E., Lake Wales Brown, R. L., NACO Fertilizer Co., Ft. Pierce Brown, T. 0., Box 96, Frostproof Brown, Mrs. V. L. Stanford St., Bartow Bryan, D. S., 510 S. Broadway, Bartow Bryan, R. L., Box 154, Bartow Buckles, W. V., P. 0. Box 86, Leesburg Bullard, Henry, Lake Wales Burch, R. W., Inc., Plant City Burden, George F., P. 0. Box 985, Winter Haven Burgis, Donald S., Box 678, Manatee Station, Bradenton Burns, Theodore C., Box 808, Palmetto Butcher, F. Gray, Univ. of Miami, Coral Gables Cadmus, Harold J., 8817 San Pedro, Tampa 9 California Fruit Growers Exchange, Research Dept.,
616 E. Grove St., Ontario, California
Call, A. H., 18472 Burto St., Anaheim, California Calumet & Hecla Consolidated Copper Co.,
Calumet, Mich.
Camp, Dr. A. F., Citrus Exp. Sta., Lake Alfred Carlton, R. A., P. 0. Box 1896, West Palm Beach Casseres, Ernest H., Dept. of Veg. Crops, Cornell, Univ.,
Ithaca, N. Y.








FLORIDA STATE HORTICULTURAL SOCIETY. 1950


Central Groves Cooperative, Lake Hamilton Chandler, L. L., Goulds Chase, Frank K., 1819 Cherokee Trail, Lakeland Chase, Frank W., Isleworth, Windermere Chase, Randall, Box 291, Sanford Chase, Sydney 0., Jr., P. 0. Box 599, Sanford Chipman Chemical Co., Inc., Box 309,
Bound Brooks, N. J.
Chissom, G. A., 1200 Sunshine Ave., Leesburg Chronister, B. S., 1108 E. Main St., Richmond, Va. Citrus Grove Development Co., Babson Park Clayton, H. G., Hort. Bldg., Univ. of Fla., Gainesville Clearwater Growers Assn., Box 299, Clearwater Clements, W. B., Box 65, Leesburg Coastes, J. L., Adams Packing Assn., Inc., Auburndale Coe, Dr. Dana G., 1425 Providence Rd., Lakeland Coe, Ray, Star Route, Bunnell Coleman, K., Speed Sprayer Co., Orlando Collins, Paul F., Haines City Colter, R. L., Box 880, Lakeland Commander, C. C., Box 2849, Tampa Connell, Ed. B., Rt. No. 1, Box 502, Valrico Connor, F. M., P. 0. Box 265, Palmetto Conover, Robert A., Sub-Tropical Exp. Sta., Homestead Cooney, Ray H., 1007 Wallace S. Bldg., Tampa Cooper, William C., Box 241, Weslaco, Texas Costa, Dr. A. S., USDA, Institute Agronimico,
Campinas, Brazil
Covington, D. D., Jr., Covington Fruit Pkg. Co.,
Dade City
Cowperthwaite, W. G., Veg. Crops Lab., Box 678,
Manatee Sta., Bradenton
Crawford, Mrs. W. T., Haines City Creighton, John T., Box 2845, Univ. Sta., Gainesville Crenshaw-MeMichael Seed Co., Box 1814, Tampa 1 Crews, Standish L., Box 179, Vero Beach Crossman, W. F., Fla. Southern College, Pi Kappa
Alpha, Lakeland
Crumb, Frank K., Box 807, Lakeland Crutchfield, Cecil M., Box 555, Auburndale Curry, Kenneth, 1618 Rose Ave., Knoxville 16, Tenn. Croce, Francisco M., Matienzo 339, San Jose,
Mendoza, Argentina
D'Albora, John V., Jr., Box 1189, Cocoa Daly, C. F., West Coast Fert. Co., Box 1094, Tampa 1 Davis, Charles P., Box 947, Winter Haven Day, William A., Box 29, Bradenton Decker, Phares, Agr. Exp. Sta., Gainesville Dekle, George W., State Plant, Gainesville Dennison, Raymond A., Dept. of Hort., Fla. Agr. Exp.
Sta., Gainesville
D'Ercole, A., 308%/ Windsor St., Lakeland Dewson, 1. B., 424 Arden Court, Ridgewood, N. J. Diamond R. Fertilizer Co., Inc., Winter Garden Dickey, R. D., P. 0. Box 2845, Univ. Sta., Gainesville Dickman, Lyle C., Ruskin Dickman, Paul B., Ruskin Diem, John J., Southern Agri. Insecticides, Inc.,
Palmetto
Dierberger Agro-Commercial LTDA., Caixa Postal 458,
S. Paulo, Brazil
Dijkman, Dr. M. J., 4018 Douglas Rd., Coconut Grove,
Miami
Dixon, W. R., P. 0. Box 144, Winter Garden Dolan, F. M., 1817 Granada Blvd., Coral Gables Donaldson, C. S., Avon Park Dowdell, R. S., Box 1907, Orlando


Dowling, Paul M., 1644 E. Livingston, Orlando Drondoski, John E., Box 1225, Ft. Pierce Dunlap, R. C., Box 668, Hialeah Dunne, Hugh J., San Antonio Dye, H. W., Niagara Chem. Div., Food Machinery &
Chem. Corp., Middleport, N. Y. Dyson, Z. V., Orlo Vista Eaton, DeWitt, Box 142, Sarasota Eddins, Dr. A. H., Potato Laboratory, Hastings Edsall, R. S., 1828 28th Ave., Vero Beach Eide, Andrew, c/o J. C. Sample, Naples Elvin, Evert, Citrus Exp. Sta., Lake Alfred Enzie, W. D., BirdsEye Snider Div., 40 Franklin St.,
Rochester N. Y.
Estes, H. 0., Box 885, Haines City Evans, Thomas E., Box 1105, Lake Alfred Everglades Fertilizer Co., Ft. Lauderdale Fascell, Michael, 1661 S. W. 22nd St., Miami Fawsett, C. F., Jr., Box 186, Orlando Feaster, 0. 0., Rt. No. 1, Box 740, Lakeland Felton, E. R., Lakeland Feustel, Win. K., Rt. T. Vanderbilt Co., 230 Park
Ave., New York 17, N. Y.
Fields, Charles E., Box 532, Winter Haven Fifield, Willard M., Agr. Exp. Sta., Gainesville Fisher, Miss Francine E., Citrus Exp. Sta., Lake Alfred Fitzpatrick, Thomas E., Box 572, Haines City Fla. Chamber of Commerce, Jacksonville Florida Geological Survey, Tallahassee Fogg, Harry W., Box 774, Eustis Food Machinery Corp., John Bean Div., 1812 W.
Washington St., Orlando
Ford, Dr. Harry W., Citrus Exp. Sta., Lake Alfred Ford, Robert, 218 E. Bay St., Lakeland Forsee, Dr. W. T., Jr., Everglades Exp. Sta.,
Belle Glade
Foy, John E., Jr., Ashcraft-Wilkinson Co., Wallace S.
Bldg., Tampa 2
Freeze, Walter, Box 2470, Clearwater Friend Sprayer Service Corp., Frostproof Friend, W. H., Box 548, Weslaco, Texas Frierson, Paul E., State Plant Board, Gainesville Frisbie, S. Lloyd, Bartow Futch, Ivey E., Box 857, Lake Placid Gainesville Garden Club, c/o Mrs. James W. Day,
Pres., 530 N. E. 7th Ave., Gainesville
Gallagher, Vincent, 18 N. E. 18th St., Delray Beach Gardner, Mrs. F. C., Lake Alfred Gardner, Dr. Frank E., 415 Parramore St., Orlando Garrett, Charles A., RFD 1, Box 216, Kissimmee Gates, Charles M., Univ. of Miami, Coral Gables Gerwe, Dr. R. D., Food Mach. & Chem. Corp.,
Lakeland
Gill, B. R., Rt. No. 1, Ft. Lauderdale Glass, Mrs. E. L., Haines City Gould, Chester N., Star Rt. Box 23, West Palm Beach Grant, Dr. Theo J., USDA, Institute Agronimico, Campinas, Brazil
Gratz, L. 0., Agr. Exp. Sta., Gainesville Graves, Forrest C., Box 606, Vero Beach Graves, J. R., Box 922, Vero Beach Green, W. F., Wilson & Toomer Fertilizer Co., Jacksonville
Greene, Barette E., Jr., Vero Beach Greene, R. E. L., Department of Agr. Econ., U. of Fla., Gainesville
Grieneisen, L., Jr., Weirsdale









FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Griffin, B. H., Jr., Box 155, Frostproof Griffin, J. A., Box 1809, Tampa 1 Griffiths, J. T., Citrus Exp. Sta., Lake Alfred Groebe, Russell A., Box 1429, Cocoa Groff, G. Weidman, Laurel Groff, H. C., Palmetto Groover, Ben H., Lake City Grossenbacher, J. C., Plymouth Grossenbacher, S. A., Box 66, Apopka Goldroeber S., U. of Miami, Box 1015, S. Miami Grove, Win. R., Laurel Growers Fertilizer Agency, Lake Alfred Guest, Mrs. Amy, 465 E. 57th St., New York, N. Y. Gunn, C. D., Rt. No. 1, Micanopy Hale, Roger H., Rt. No. 1, Palmetto Hall, C. B., U. of Fla., Horticulture Dept., Gainesville Halsey, L. H., Fla. Agr. Exp. Sta., Gainesville Halter, E. T., Box 110, Palm Beach Hamilton, Joseph, Rt. No. 1, Box 798, Yuma, Arizona Hamilton, Mrs. Madelaine, 630 Ave., B., N.W.,
Winter Haven
Hamm, Freeman R., City of Lakeland, St. Dept.,
Lakeland
Hammerstein, C. P., Hammerstein Groves, Hollywood Hanna, L. C., Hanna Rd., Lutz Harding, Dr. Paul L., U.S.D.A., Orlando Harkeson, J. E., 624-7th St., N.W., Winter Haven Harkness, R. W., Sub-Tropical Exp. Sta., Homestead Harshman, W. W., Highlands Fertilizer Co., Sebring Hardwick, J. E., Jr., P. 0. Box 669, West Palm Beach Harz, A. W., 13 W. Underwood Ave., Orlando Hartt & Son, Inc., Box 308, Avon Park Hatch, Hugh B., Dunedin Hayman, W. Paul, P. 0. Box 711, Bartow Hayslip, Norman C., Box 1198, Ft. Pierce Hayter, W. Burns, P. 0. Box 536, Leesburg Hayward, Wyndham, Lakemont Gardens, Winter Park Hector Supply Co., Box L No. 1311, Miami Heindrick, E. P., 5830 N.W. 7th Ave., Miami Henderson, H. Cecil, Box 1448, Winter Haven Hendrickson, Rudolph, Citrus Exp. Sta., Lake Alfred Hennes, Jaffa E., S. Lake Apopka Citrus Growers Assn.,
Oakland
Henry, Arthur M., 1177 Zimmer Dr., N.E.,
Atlanta, Ga.
Henry, W. M., Box 508, Plant City Herlong, Byron, Leesburg Hill, Arhur M., Jr., Box 306, Vero Beach Hills, Walter A., P. 0. Box 1055, Lake Worth Hines, T. R., Box 397, Tampa Hodnett, J. Victor, Box 958, Winter Haven Holcomb, E. D., Jr., Winter Haven Holden, B. Heath, Rt. No. 2, Box 486, Homestead Holtsberg, Harold, 132 N. 12th St., Ft. Pierce Holzcker, Richard, Babson Park Hope, M. E., 513 W. Magnolia Ave., Dade City Hopkins. E. F., Citrus Exp. Sta., Lake Alfred Horton, Mrs. Wm. H., Haines City Howard, Frank L., Box 996, Winter Haven Huff, Norman V., Box 5, Winter Haven Huggart, Richard, Box 442, Bartow Hughes Seed Store, 116 S. Miami Ave., Miami 36 Hughes, W. H., Box 287, Elsa, Texas Hundertmark, B. W., Clewiston Hunter, George J., Orlando Livestock Co., Deer Park Hunter, William P., 1039 W. Cypress St., Gainesville Huppel, J. B., Windermere


Husmann, Dr. W., 646 Seminole Drive, Winter Park Hutchinson, J. H., Rt. No. 1, Box 139K, Avon Park Idlewild Grove, Rt. No. 4, Box 1080, Tampa Ingram, Dr. Esther M., 204 Professional Bldg.,
Winter Haven
Jacobs, W. A., 317 S.E. Fifth Ave., Delray Beach Jalarmy Citrus Groves, Minneola James, Robert H., Box 635, Dunedin Jamison, F. S., University of Fla., Gainesville Jimenez, M. A., Minute Maid Corp., Plymouth Joffre, David C., 29 S. Court St., Orlando John's Plants, Seeds & Bulbs, c/o John Masek, Apopka Johnson, J. A., P. 0. Box 501, Avon Park Johnson, R. S., 929 E. 10th St., Sarasota Johnson, Warren 0., Box 1058, Lakeland Jones, H. L., State Plant Board, Gainesville Jones, W. J., Di Giorgio Fruit Corp., Winter Haven Jordahn, A. C., Box 292 Coconut Grove, Miami 33 Jorgensen, M. C., Box 233, Ruskin Kanawha Groves, 209 Gates Bldg., Charleston, W. Va. Karst, Art, Box 1110, Orlando Kasper, P. E., P. 0. Box 906, Tampa Kazaros, Robert S., 1610 Delaney St., Orlando Keel, Darnell, 2706 Price Ave., Tampa 9 Keene, R. D., Box 338, Winter Garden Keil, P. F., 530 N. E. St., Raleigh, N. C. Kelbert, David G. A., Box 678, Manatee, Sta.,
Bradenton
Kelly, Dr. Reba Allen, Fla. Southern College, Lakeland Kelsheimer, E. G., Box 678, Manatee Sta., Bradenton Kempf, Mrs. E. J., King Grove, Eustis Kendall, Harold E., Box 868, Goulds Kent, L. C., Box 806, Orlando Kesterson, J. W., Citrus Exp. Sta., Lake Alfred Kew, Theo. J., 1721 Westchester Ave., Winter Park Kime, Charles D., Box 232, Ft. Pierce King, John R., 1201 4th St., N.E., Winter Haven King, Percy M., Box 42, Quincy Kingshury, Miss Joan, Box 124, Lake Wales Kirkley, Al. C., Box 1112, Winter Haven Knox, Jean H., P. 0. Box 898, Haines City Kransch, Kenneth, 1000 Widensor Bldg.,
Philadelphia 7, Pa.
Krome, Isabelle B., Miami Krome, William H., Box 596, Homestead Krome, Mrs. William J., Box 596, Homestead Kuitert, L. C., Exp. Sta., Gainesville Ladeburg, C. F., Box 6085, West Palm Beach Lamb, Geo., Marianna Lamont, Henry, Rt. No. 2, Ft. Pierce Larson, L. J., Winter Haven Lawless, W. W., 1645-16th St. N.W., Winter Haven Lawrence, Fred P., 402 Newell Hall, Univ. of Fla.,
Gainesville
Lee, W. S., Box 176, Mims Leibovit, Arthur B., Winter Rose Apts.,
403 N. Olive Ave., West Palm Beach
Leonard, Chester D., 631 "H" N.W., Winter Haven Lewis, D. E., Box 1171, McAllen, Texas Lewis, H. F., Terra Ceia Link, 0. D., Davie Rd., Ft. Lauderdale Lippincott, Mrs. W. A., P. 0. Box 997, Stuart Lipscomb, S. F., Bartow Little, C. S., Odessa
Little, H. W., 311 Horticulture Bldg.,
Univ. of Florida, Gainesville
Livingston, Bert, 3024 Fair Oaks Ave., Tampa -









FLORIDAN STATE HORTICULTURAL SOCIETY, 1950 XI


Lockett, Norwood A., Box 358, Leesburg Logan, J. H., County Agent, Box 540, Clearwater Long, Wallace T., Box 1198, Ft. Pierce Lord, E. L., Sub-Tropical Gardening, Ft. Myers Lorz, A. P., Fla. Agr. Exp. Sta., Gainesville Loucks, K. W., Lake Alfred Lucas, G. H., Peninsular Fertilizer Works,
Box 3272, Tampa
Lundberg, Ernest C., 1319 N.W. Second Ave.,
Gainesville
Lyle, J. I., Rt. No. 5, Box 888, Orlando Lynch, S. John, Rt. No. 1, Box 185B, Homestead MacDowell, Louis G., Box 1720, Lakeland Mackay, Mrs. R. F. B., Lake Alfred Madsen, H. S., Lake Morten Apts., Lakeland Magie, Robert 0., 2906 Ninth Ave., W., Bradenton Malcolm, J. L., Rt. No. 2, Box 508, Homestead Manfre, Stephen J., 742 Liberty Ave., Cur. Essex St.,
Brooklyn, N. Y.
Marler, Buck, Fla. Fertilizer Co., Lakeland Marlow, Win. L., Box 1709, Jacksonville Martin, Chas. H., 802 E. Hamilton, Tampa Martsolf, J. D., Ocklaws Masek, John, Apopka
Masten, Harold R., 151 Grace Terrace, Palm Beach Mathias, A. F., Box 183, Lake Hamilton Mathias, F. C., Haines City Citrus Grove Association,
Haines City
Maulhardt, Richard F., Rt, No. 1, Box 579,
Camarillo, Califomnia
Maxcy Fertilizers, Inc., E. R. Johnston, Frostproof 'Maxwell, Lewis S., Jackson Grain Co., Tampa 1 Maxwell & Anderson, San Mateo Mayeux, Herman S., Fla. Agr. Supply Co., Jacksonville Mayfield, Harry, 608 Easton, Lakeland Mayo, Nat, Ocala
Mayo, The Honorable Nathan, Commissioner of Age.,
Tallahassee
Meckstroth, Dr. C. A., 415 N. Parramore, Orlando Mell, James R., 409 Candler Bldg., Atlanta, Ga. Menninger, Edwin A., Stuart Mercer M. T., Box 181, Coral Gables 34. Merrill, G. P., State Plant Board, Gainesville Merrill, W. H., State Plant Board, Gainesville Meserole, Mrs. George, San Mateo Michael, Joe E., Box 324, Palmetto Miller, C. E., 2598 Taylor St., San Francisco, Calif. Miller, E. W., P. 0. Box 1435, Clearwater Miller, H. N., Dept. of Plant Pathology, Gainesville Miller, Leon, Rt. No. 6, Orlando Miller, Ralph L., Plymouth Citrus Growers Association,
Plymouth
Miner, James T., P. 0. Box 341, Bonynton Beach Minute Maid Corp., Plymouth Mooers, Neal D., Babson Park Moore, Clarence H., Drawer 31, Winter Havens Monty, A. F., Box 814, Winter Haven Morgan, Charles E., 1116 E. Livingston, Orlando Morrell, P. C., 431 E. Central Ave.,
Eula Plaza, Apt. 402, Orlando
Morrow, William B., 1525 Sunset Place, Ft. Myer, Morse, John, 729 Indian River Dr., Ft. Pierce Morton, J. F., 113 Mendoza, Coral Gables Mounts, M. U., County Agent, Box 70, W. Palm Beach Mowry, Harold, 2455 University Station, Gainesville Mullen, Harris, Fla. Grower Magazine, Inc., Tampa Mullinax, H. S., 315 Ave. B, N.E., Winter Haven


Mustard, Margaret J., Box 1015, Univ. of Miami,
Miami
Myers, C. J., General Delivery, Tallahassee Myers, Forrest E., Fla. Agr. Extension Service,
Gainesville
McBride, J. N., Union Sta., Bldg., Savannah, Ga. McCallum, J. B., Hastings McClanahan, H. S., State Plant Board, Gainesville McClure, George G., Lake Alfred McCoy, Sinclair, 29th Floor, 20 N. Wacker Dr.,
Chicago 6, Ill.
McCubhin, E. N., Potato Laboratory, Hastings McDonald Division. Clinton Foods, Inc.,
P. 0. Box 500, Auburndale
McDuff, 0. R., Adams Packing Assn., Inc.,
Auhurndale
McIntyre, A. E. C., Box 112, Homestead Mcl~innis, Ronald B., Brown Citrus Machinery Corp.,
401 S. Greenleaf Ave., Whittier, California McPeck, John IK., 328 S. Lakeview Dr., Sebring Nahors, C. M., 1007 Wallace S. Bldg., Tampa Nanney, W. C., 2419 7th Ave., W., Bradenton National Fertilizer Assn. 616 Continental Bldg.,
Washington 5, D. C.
Neal, J. H., Hercules Powder Co.,
134 Peach Tree St., N.W., Atlanta, Ga. Neff, Frank, 605 W. Warren, Tampa Nelson, Roy 0., Univ. of Miami, Box 1015, S. Miami Nettles, Victor F., Hurt. Dept. Agr. Exp. Sta.,
Gainesville
New Smyrna Beach Garden Club, New Smyrna Beach Newins, Harold S., Director School of Forestry,
Univ. of Fla., Gainesville
Nicholson, Joe, 702 McLendon St., Plant City Nikitin, A. A., Tennessee Corp. Res. Labs.,
Box 89. College Park, Ga.
Noble, C. V., 1460 N. Brove St., Gainesville Norman, Gerald C., 2170 Fawoalt Road. Winter Park Norris, R. E., County Agent, Tavares O'Byrne, Frank M., Jr., 630 E. 38th St., Hialeah Ocbse, Dr. J. J., Univ. Branch Box 156, Miami Oglesby, R. M., Box 180, Bartow O'Kelley, E. B., ACL Railroad Co., Jacksonville Olsen, H., Davenport O'Shea, Col. Kevin, 2911 Riverview Blvd., Bradenton Palmer, Charles, 340 E. Lemon St., Bartow Palmer, J. M., Box 936, Lutz Pan American Metal Products Co., Inc.,
401 N.W. 71st St., Miami
Paquin, W. E., Box 519, Winter Garden Parker, Coleman H., Box 919, Winter Haven Parris, G. K., Watermelon Laboratory, Leeshurg Patrick. Dr. Roger, P. 0. Box 403, Winter Haven Pedersen, W. C., Lake Wales Peebles, T. A., Box 877, Vero Beach Pennsylvania Salt Manufacturing Co.,
1000 Widener Bldg., Philadelphia 7, Pa. Perkins, Bernard C., Sehring Pfister, Mrs. H. C., Box 692, Winter Haven Phelps, George W., Stauffer Chemical Co.
Winter Haven
Pinkerton, David W., City Point Pipkio, W. A., Safety Harbor Plaquemines Parish Exp. Sta., Louisiana State Univ.,
Att: Mr. Ralph T. Brown, Superintendent,
Diamond, La.
Platts, Norman G., Rt. No. 2, Box 242, Ft. Pierce


XVII








VIIIFLORIDA STATE HORTICULTURAL SOCIETY, 1950


Pollard, W. R., Box 23, Bradenton Potash Co. of America, 50 Broadway, New York, N. Y. Pratt, Robert M., Citrus Exp. Sta., Lake Alfred Price, R. C., 2826 Oak St., Jacksonville Pride, Richard E., Frostproof Princess Grove, Box 227, Lake Wales Pulley, George, P. 0. Box 13, Winter Haven Rainey, B. T., Dolomite Products, Ocala Ramsey, Vernon E., P. o. Box 7, Suffolk, Va. Bawls, Glenn, Plymouth Reark, J. B., Univ. of Miami, Miami Reasoner, Eghert S., Box 828, Bradenton Reed, H. M., Fla. Agr. Exp. Sta., Gainesville Reints, J. E., Winter Haven Reitz, Dr. J. Wayne, Provost of Agr., Univ. of Fla.,
Gainesville
Reitz, H. J., Citrus Exp. Sta., Lake Alfred Reuther, Dr. Walter, 415 N. Parramore St., Orlando Reynolds, B. T., Anburndale Rich, Frank H., Box 130, Winter Haven Riebbomn, J. H., Box 1401, Lakeland Riegel, Mark, Experiment, Ga. Riester, D. W., American Can Co., Box 1732, Tampa Roberts, A. S., Box 694, Ocala Roberts, Pasco, Box 728, St. Petersburg Robinson, H. B., Box 2266, Miami 13 Rock, Fairfield, Homestead Rogers, H. S., Box 823, Winter Haven Rogers, J. T., P. 0. Box 448, Plant City Rollins, C. F., Clearwater Root, C. A., Winter Haven Roper, R. R., Winter Garden Rosenberger, Stanley, Agr. Ext. Service, Gainesville Ross, Stuart W., Lake Wales Rounds, Marvin B., 224 N. Michigan Ave., Glendora,
California
Rouse, A. H., Citrus Exp. Sta., Lake Alfred Rowe, W. M., 1007 Wallace S. Bldg., Tampa Rueble, Dr. George D., P. 0. Box 604, Homestead Rumpsa, Paul L., Drawer 608, Avon Park Ruprecbt, R. W,, Box 327, Sanford Ruskin Vegetable Coop., Ruskin Russell, J. C., P. 0. Box 177, Sanford Sahlherg, Nils, Box 252 C-19, Orlando Sample, J. M., Box 113, Lake Hamilton Sampson, R. H., Box 7, Mango Saurman, A. Vemnon, Box 686, Clearwater Savage, Clifford B., 416 El Prado Ave., W. Palm Beach Savage, Zack, Agr. Exp. Sta., Gainesville Sawyer, David P., Box 1266, Ven Beacb Schaaf, Harold H., Box 349, David City, Nebraska Schrader, Otto Lyra, Runa Santa Clara 256,
Rio de Janeiro, Brazil
Schock, W. V., P. 0. Box 462, Winter Haven Schulz, W. H., Winter Haven Scott, A. G., Box 651, Winter Haven Sealey, J. H., Box 124, Arcadia Seims, Mrs. Roy E., Box 663, Avon Park Sexton, Mrs. Eva., Sexton Groves, Winter Haven Sexton, W. E., Ven Beach Seymour, Frank, Box 1327, Lakeland Sharpe, R. H., Fla. Agn. Exp. Sta., Gainesville Shinn, Charles M., Lake Alfred Shoupe, Arthur H., 1130 Fifteenth Ave., N.,
Lake Worth
Showalter, B. K., Agn. Exp. Sta., Gainesville Siamonton, W. A., Citrus Exp. Sta., Lake Alfred


Silver Lake Estates, Ltd., Leesburg Simmons, Paul U., P. 0. Box 260, Winter Haveni Singleton, Gray, 125 E. Palm Drive, Lakeland Sites, J. WV., Citrus Exp. Sta., Lake Alfred Skiute, Morris, 1658 21st Ave., N., St. Petersburg Smiley, Nixon, Homestead Smith, Al G., Box 88, Palmetto Smith, F. B., Agr. Exp. Sta., Gainesville Smith, J. Lee, Box 6, Homestead Smith, Laurin G., Tennessee Corp.,
619-27 Grant Bldg., Atlanta 1, Cs. Smiths, Paul, 415 N. Parramore St., Orlando Snell, B. R., Avon Park, Snodgrass, William, Rt. No. 1, Clermsont Soil Science Foundation, Lakeland Soowal, J. M., 822 Arlington Ave., Orlando Soule, M. J., Jr., Univ. of Miami, Box 1015, S. Miami South Florida Motor Co., Sebring Souviron, Max J., 2845 S.W. 22nd Terrace, Miansi 34 Spalding, A., Rt. No. 2, Box 66, DeLand Speer, H. L., Box 326, Belle Glade Spencer, Dr. Ernest L., Veg. Crops Lab.,
Box 678, Manatee Sta., Bradenton
Spencer, Herbert, U.S.D.A., Box 112, Ft. Pierce Spencer, T. C., Haines City Sprott, Kingswood, Lake Wales Stabler, D. K., Winter Haven Stahl, Dr. A. L., Univ. of Miami, South Canspus,
Miami
Stauffer Cemical Co., Box "K", Apopka Sterling, H. 0., Box 176, Bartowv Stevens, H. E., Amherst Apts., Orlando Stewart, Tom B., Box 6, DeLand Stirling, Walter, Rt. No. 1, Ft. Lauderdale Stoddard, David L., Room 205, Walcaid Bldg.,
Bradenton
Stoner, Dr. Warren H. Everglades Exp. Sta.,
Belle Glade
Sturrock, David, 1021% Camellia Rd., W. Palm Beach Sturrock, Thomas T., 1021%/ Camellia Rd.,
West Palm Beach
Suit, R. F., Citrus Exp. Sta., Lake Alfred Sumnmerfield Nursery Co., Weirsdale Sutton, Cliff, 806 Lucerne Terrace, Orlando Swank, George, Central Fla. Exp. Sta., Sanford Swann, Thomas, Winter Haven Swartsel, J. A., Reints Apt., Apt. No. 1,
1st St. & Lake Silver, N.W., Winter Haven Swartsel, R. V., Lake Gem Taber, Ceo. L., Jr., Glen St. Mary Nurseries Co.,
Glen St. Mary
Tait, W. L., P. 0. Box 695, Winter Haven Talbert, Dale, Ven Beach Taylor, Mrs. Bright, P. 0. Box 623, Ocala Taylor, J. J., State Chemist, Tallahassee Thomas, W. W., NACO Fertilizer Co.,
2005 Lake Sue Dr., Orlando
Thompson, Robert, Box 1231, Orlando Thompson, W. L., Box 1074, Lake Alfred Thornton, R. P., Box 2880, Tampa Thullbery, H. A., Lake Wales Thurshy, Isabelle S., Box 68, Orange City Tiedtke, John, Clewiston Tilden, Fred, Winter Garden Timmons, Mrs. Ruth, Belle Glade Tindal, George, Ft. Pierre Cooperative, Ft. Pierce Tisdale, W. B., Age. Exp. Sta., Gainesville


XVIII











FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Toffaleti, James P., Box 1281, Orlando Tomasello, Rudolph P., 911 Bignonia Rd.,
West Palm Beach
Tower, John B., Rit. No. 1, Box 60, Homestead Townsend, G. R., Box 356, Belle Glade Tropical Agriculture, S. A., Calle Ermita S/N,
La Habana, Cuba
True, H. H., 438 N.E. 8th Ave., Ft. Lauderdale Twenhofel, Dr. W. W., P. 0. Box 1231, Orlando United Growers & Shippers Assn., Orlando United Growers and Shippers Assn.,
14 E. Hamilton St., Tampa Van Clief, W. C., Winter Haven Van Horn, M. C., 4517 Beach Tree Circle E.,
Jacksonville
Van Kirk, J. C., RFD No. 1, Ft. Lauderdale Veldbuis, M. K., U. S. Citrus Production Station,
Winter Haven
Volk, Gaylord M., Dept. of Soils, Exp. Sta., Gainesville Voorhees, R. K., Box 232, Ft. Pierce Wagner, W. E., Geary Chemical Corp.,
Empire State Bldg., New York, N. Y. Waldron, Max, Rit. No. 1, Ft. Lauderdale Walker, Marvin H., 720 Lakeshore Blvd., Lake Wales Walker, Seth S., 3002 Waverly Ave., Tampa 9 Wallace, Geo. Ri., Lake Park Walter, J. M., Vegetable Crops Lab.,
Box 678, Manatee Sta., Bradenton
Wander, Dr. I. W., Citrus Exp. Sta., Lake Alfred Ward, W. F., Box 177, Avon Park Ware, C. E., 1411 N. Ft. Harrison, Clearwater Warren, Alfred, Rit. No. 1, Box 212, Vero Beach Watson, E. Ri., Oakadia Groves, Nursery Rd.,
Clearwater
Watson, J. D., 804 S. Dargan, Florence, S. C. Wechtsa, L. M., U. S. Sugar Corp., Clewiston Wenzel, Dr. F. W., Citrus Experiment Station,
Lake Alfred
West, Erdman, 101 Newell Hall, Univ. of Fla.,
Gainesville


West Coast Fertilizer Co., 1601-31st St., Tampa Westgate, P. J., Central Fla. Exp. Sta., Sanford White, Alec, 5506 Seminole Ave., Tampa White, J. F., Julius Hyman Co., Denver, Colorado Whitmore, Al H., Box 2111, Orlando Williams. H. A., Kilgore Seed Co., Ocala Williams, Lyons H., Jr., F. H. Woodruff & Sons. Inc.,
Box 815, Coral Gables
Williams, Miss Myra G., Rockledge Williams, Ralph E., 1134 N. Yates Ave., Orlando Wilson, A. E., Citrus Experiment Station, Lake Alfred Wilson, Don H., Bartow Wilson, E. H., 91 Norman Bridge Rd.,
Montgomery, Ala.
Wilson, Gaines R., 3853 Little Ave., Coconut Grove Wilson, H. L., Box 156, Bartow Wilson, John Ri., 1036 Francis St., Box 6206,
West Palm Beach
Wilson, J. W., Central Fla. Exp. Sta., Sanford Wilson, Leo H., Box 48, Bradenton Wilson. Robert A., Box 25, Hohe Sound Wilson, Robert G., Rit. No. 2, Box 594, Miami Winston, J. R., 415 N. Parramore, Orlando Winter Garden Ornamental Nursery, Inc.,
Box 428, Winter Garden Wirt, Erle L., Jr., Bahson Park Wolf, Emil A., Everglades Exp. Station, Belle Glade Wolf, Frederick A., Duke University, Durham, N. C. Wolfe, Dr. H. S., Head Dept. of Hort., Univ. of Fla.,
Gainesville
Wolfenbarger, D. 0., lit. No. 2, Box 508, Homestead Woods, V. E., Box 734, Davenport Yonge, J. Ri., Box 788, Ft. Pierce Young, Dr. C. T., Box 948, Plant City Young, T. W., American Fruit Growers, Ft. Pierce Ziegler, Louis W., College of Age., Univ. of Fla.,
Gainesville
7411, L. H., 813 N. Federal Highway, Delray Beach Zolfay, John C., Frostproof II












PROCEEDINGS OF THE FLORIDA STATE HORTICULTURAL SOCIETY, 1950


VOLUME LXIII


FLORIDA STATE HORTICULTURAL SOCIETY, 1950


PRINTED 1951


CONTENTS
Officers for 1950 ------------------------------------------------------ . . . IV
Officers for 1951 ---------------------------------------- ----------------------------------------------------------------- V
Constitution and By-Laws --------------------------------------------------------------------- ---------------_ VII
Award of Honorary Memberships. --------- -------------------------- _ -------------------------------- IX
List of Members --------- ------ __ ---------------- ------- __ ------- -------- ------------------------------------------ XI
President's Annual Address, Leo H. W ilson, Bradenton ---- ----------------------------------- 1,
Partial Mobilization and the Florida Fruit and Vegetable Industry, Dr. J.
Wayne Reitz, Provost for Agriculture, University of Florida, Gainesv ille --- ---------------------------------------------------- ---- ---- ----------- - --------------------------- 3


CITRUS SECTION
The Effect of 2,4-D on Pre-Harvest Drop of Citrus Fruit Under Florida
Conditions, F. E. Gardner, Philip C. Reece and George E. Horanic, U. S. Department of Agriculture, Orlando. . ----------------------------------The Chemical Composition of Irrigation Water Used in Citrus Groves,
I. W. Wander and H. J. Reitz, Citrus Experiment Station, Lake Alfred
Ground Water Resources of Florida, Herman Gunter, Florida Geological
Survey, T allahassee ------------------------------------------------------------------ --------------_ -----Portable Irrigation on the Ridge, Morton Howell, Waverly -------------------------------The Response of Young Valencia Orange Trees to Differential Boron Supply
in Sand Culture, Paul F. Smith and Walter Reuther, U. S. Department of A griculture, O rlando . __ -----------------------------------Rio Grande Gummosis, Its Occurrence in Florida Citrus, J. F. L. Childs,
U. S. Department of Agriculture, Orlando . . .
Present Status of Spreading Decline, R. F. Suit and H. W. Ford, Citrus
Experim ent Station, Lake Alfred ------------------ . . .
The Purple Mite and Its Control, W. L. Thompson and J. T. Griffiths, Jr.,
I Citrus Experiment Station, Lake Alfred .

Florida's Stake in Plant Quarantine Enforcement, Avery S. Hoyt, Chief,
Bureau of Entomology and Plant Quarantine, Washington, D. C__ .
Possibilities for the Use of Concentrated Sprays on Citrus in Florida, James
T. Griffiths, C. R. Stearns, Jr., and W. L. Thompson, Citrus Experiment Station, L ake A lfred . _ . _ ----------------------









FLORIDA STATE HORTICULTURAL SOCIETY, 1950


The Effect of Variable Potash Fertilization on the Quality and Production
of Duncan Grapefruit, John W. Sites, Citrus Experiment Station, Lake
A lf red -------------------------------------- __ -------------------------------------------------------------------------- 60
Panel on Parathion, Howard A. Thullbery, Lake Wales -------------------------------------- 68

VEGETABLE SECTION
Control of Late Blight and Gray Leaf Spot of Tomatoes with New Fungicides, Robert A. Conover, Florida Agricultural Experiment Stations,
Sub-Tropical Experiment Station, Homestead . ----------------------------------------- 89
Fertilizer-lnsecticide Combination for Armyworm, Mole-Cricket and Wireworm Control, D. 0. Wolfenbarger, Florida Agricultural Experiment Stations, Sub-Tropical Experiment Station, Homestead, and E. G.
Kelsheimer, Florida Agricultural Experiment Stations, Vegetable Crops
L aboratory, B radenton -------------------------------------------------------------------------------------- 93
Toxic Insecticide Residues of Vegetables, J. W. Wilson, Florida Agricultural Experiment Stations, Central Florida Experiment Station,
S anford . _ ----------------------------------------------------------------------------------------- 95
Processing and Labeling Pesticides, M. C. Van Horn, Jacksonville ---------------- 99
The Role of the Regional Vegetable Breeding Laboratory in Breeding and
Testing New Vegetable Varieties, S. H. Yarnell, U. S. Regional Vegetable Breeding Laboratory, Charleston, South Carolina ----------------_ ------- 102
New Vegetable Varieties for Florida, David G. A. Kelbert, Florida Agricultural Experiment Stations, Vegetable Crops Laboratory, Bradenton 108 Effect of Low Nitrate Nitrogen on Growth of Potatoes, Gaylord M. Volk and
Nathan Gammon, Jr., Florida Agricultural Experiment Station,
G ain esville . . ------------------------------------------------------------------------ 112
Effects of Soluble Soil Salts on Vegetable Production at Sanford, Philip J.
Westgate, Florida Agricultural Experiment Stations, Central Florida
Experim ent Station, Sanford ------------ . --------------------------------------- . 116
A Nematode Attacking Strawberry Roots, A. N. Brooks, Strawberry Laboratory, Plant City, and J. R. Christie, U. S. Department of Agriculture,
S anford -------------------------------------------- ----------- ------------------------------------------------------- 123
Nitrogen Transformation in Seedbeds as Affected by Nematocidal Treatment, Ernest L. Spencer and Amegda Jack, Florida Agricultural Experiment Stations, Vegetable Crops Laboratory, Bradenton ------------- . 125
Graywall of Tomatoes, Warren N. Stoner, Florida Agricultural Experiment
Stations, Everglades Experiment Station, Belle Glade . __ -------- _ 129
Quality of Florida Potatoes and Some of the Factors Affecting Quality,
R. E. L. Greene, Florida Agricultural Experiment Station, Gainesville 136
Mulching Vegetable Crops with Aluminum Foil, Donald S. Burgis, Florida
Agricultural Experiment Stations, Vegetable Crops Laboratory,
B raden ton ----- . . ___ . . 141
Transitory Effects of 2,4-D on the Watermelon Plant When Absorbed Through the Roots, Clyde C. Helms, Jr. and G. K. Parris, Florida Agricultural Experiment Stations, Watermelon and Grape Investigations
Laboratory, Leesburg ------------ ___ --- _ . ----------------- __ --- ----- --- . ------------ 144








XXII


FLORIDA STATE HORTICULTURAL SOCIETY, 1950


PROCESSING SECTION
Comparison of Plating Media Used for the Estimation of Microorganisms
in Citrus Juices, E. C. Hill and L. W. Faville, Citrus Experiment
Station, Lake A lfred . __. 146 Relative Efficiencies of Several Liquid Presumptive Media Used in the
Microbiological Examination of Citrus Juices, L. W. Faville and E. C.
Hill, Citrus Experiment Station, Lake Alfred ------------------------------------------------ 150
Storage Changes in Citrus Molasses, R. Hendrickson and J. W. Kesterson,
Citrus Experiment Station, Lake Alfred ------------------- ------------------------------------ 154
An Index of Pasteurization of Citrus Juices by a Rapid Method of Testing for
Residual Enzyme Activity, Theo. J. Kew and M. K. Veldhuis, U. S. Citrus
Products Station, W inter Haven -------------------------------------- -------------- ---------- 162
Storage Changes in Frozen Concentrated Citrus Juices-Preliminary Report, Edwin L. Moore, Richard L. Huggart, and Elmer C. Hill, Citrus
Experim ent Station, Lake Alfred --------------- ---------------------- ----------------------------- 165
A Method for Estimating Soluble Solids in Dried Citrus Pulp, Owen W.
Bissett, U. S. Citrus Products Station, Winter Haven ----------------- . 174

ORNAMENTAL SECTION
The Genus Allamanda in Florida, Egbert S. Reasoner, Bradenton.__ ----------- 179
Some Ornamental Trees and Shrubs Native to South Florida, Geo. D.
Ruehle, Florida Agricultural Experiment Stations, Sub-Tropical Experim ent Station, H om estead . -------------------------- ------------ . ------- _ 180
The American Hibiscus Society, Norman A. Reasoner, Bradenton ----------_----- 183
Interesting Uses of Woody Plants, George L. Taber, Glen SL. Mary-. . 187 Soil Sterilization, H. N. Miller, Florida Agricultural Experiment Station,
G ain esville ---------------------------------------------------------------------------------------------- ---------- 190
Greenhouse Foliage Plants in Florida, Peter Pearson, Plymouth ----------------- 192
The Daylily in Florida, Wyndham Hayward, Winter Park. ---------------------- 194
Horticultural Research with Camellias, G. H. Blackmon, Florida Agricultural Experiment Station, Gainesville. ------------------------------------- -------------- 198
Notes on Camellia Diseases, Erdman West, Florida Agricultural Experim ent Station, G ainesville . . . 200 Factors Affecting the Keeping Quality of Cut Flowers, R. D. Dickey, Florida Agricultural Experiment Station, Gainesville . -------------------------------- 203
Insect Control on Ornamental Plants of the Home Garden, L. C. Kuitert,
Florida Agricultural Experiment Station, Gainesville ----------------- . 206

KROME MEMORIAL INSTITUTE
Fairchild Tropical Garden, Charles H. Crandon, Coconut Grove ----------_----- _ 209
Radio Garden Clubs, Pasco Roberts, St. Petersburg ------------------ . 213
We Make A Men's Garden Club Tick, Bert Livingston, Tampa . . 215







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


XXIII


Fruit Gift Packages, Edward A. Ash, Homestead -------------------------------------------- ----- 217
Observations of Some of the Newer Mangos During the Year of 1950, L. H.
Zill, D elray B each ------------------------------------------ --------------------------------------------------- 219
Monthly Meetings on Tropical and Sub-Tropical Fruits, M. U. Mounts,
W est P alm B each ------------------------------------------------------------------ ---_---------------------- 220
Marketing Fresh Lychees, DeWitt Eaton, Sarasota . ---------------- 222
A Survey of Diseases Lethal to Tahiti (persian).Limes in Dade County,
C. M. Gates and M. J. Soule, Jr., University of Miami, Coral Gables. 225 Packaging and Storage of Persian Limes, Margaret J. Mustard, University
of M iam i, Coral G ables -----_ -------------- --------------------------------------------------------------- 228
Studies of Stylar End Rot of Tahiti Limes, Robert A. Conover, Florida
Agricultural Experiment Stations, Sub-Tropical Experiment Station,
H om estead --------------------------------------------------- . ---------------------------------- 236
Twenty Years After, H. S. Wolfe, College of Agriculture, University of
F lorida, G ainesville . ---------------- --------------------------------------------------- --------- 240
Tropical and Sub-Tropical Fruits in Pinellas County, C. E. Ware, Clearw ater . ----------------------------- --------------------- : ------------------------ ----------------------------------- 245
The Future of Tropical and Sub-Tropical Fruits in Florida, E. V. Faircloth,
W est P alm B each ----------------- ----------------------------------------- ------------------------------------ 247
The Propagation of Sub-Tropical Plants by Cuttings, A Progress Report,
J. J. Ochse and J. B. Reark, University of Miami, Coral Gables -------- ----- 248
Weed Control Studies Around Young Avocado Trees, Roy W. Harkness,
Florida Agricultural Experiment Stations, Sub-Tropical Experiment
Station, H om estead -----_---------- ------------- . 251
The Introduction into the United States and the Culture of Eleocharis
Dulcis, The 'Matai' of China, G. Weidman Groff, Lingnan Plant Exchange, L aurel --------------------- ------------- __ ----------_ ----------- -------------------------------- 262
Additional Notes on Mango Budding, S. John Lynch and Roy Nelson, University of M iam i, Coral Gables . _ . . 266 ANNUAL REPORTS
Report of Executive Com m ittee . . _ . . 269 R eport of T reasurer. . . . . . 270 General Business Meeting of Society, Winter Haven, Oct. 31, and Nov.
2, 1950 . . 271 R esolutions . _ . _ . . . _ . . . . 271 N ecrology Com m ittee . . . . 272











LEO H. WILSON
Bradenton

It is with keen pleasure I welcome the members and friends of this, the sixty third session of the Florida State Horticultural Society. We have experienced many startling events since our meeting one year ago in Tampa. Increased returns have been received for horticultural and agricultural products. We have been saddened by the loss of friends and the ravages of war. We look to the future with hopes for peace and security.
The 1949 proceedings of the sixty second session of the Florida State Horticultural Society, relates the passing of the late Frank Stirling of Davie, Florida, immediate past President of the Society. Every member I am sure joins me in paying tribute to one of Florida's leading Horticulturists. Frank was a loyal member, and his going has been a great loss to the horticultural interests of Florida.
The Korean war, now coming to a close, has taken the lives of thousands of our American men. May we pay homage to the gallant fighting of our soldiers who paid the supreme sacrifice, and those wounded and missing in action. The United States, together with other U.N. forces have about won this war. My humble prayer is we will win a lasting peace.
The so-called "Florida Hurricanes" have been a dime a dozen this season. We have experienced ten hurricanes with two hits on Florida. The Gulf of Mexico blow that struck Cedar Key, did a tremendous damage to this West Coast town. The second hurricane struck in the Miami, Hollywood, Okeechobee, Indian River Section. An estimate of $15,000,000 dollar damage has been reported. Florida's East Coast Agricultural interest suffered heavy losses. The damage to the citrus crop from the lower


East Coast, extending North through Eastern Polk County, Orange and Lake Counties, estimate around 3,000,000 boxes of fruit, with grapefruit running 2,500,000 boxes and all other citrus fruits 500,000 boxes. These figures are subject to change as more damage shows up, especially the heavy drop that occurs from bruises and thorn injury.
Florida's agricultural interest is continually being subjected to the introduction and attack by foreign insect pest and diseases. The dreaded South American disease known as Tristeza that has killed thousands of citrus trees in that country, may be present in the State of Louisiana. Two hundred trees in a planting on the Mississippi River Delta near New Orleans, have died recently from Tristeza, or some other form of tree decline. If not Tristeza, it could be Quick Decline. This form is taking a heavy toll of citrus in California. Quick Decline might be termed a twin brother to Tristeza. The Florida Experiment Station, the United States Department of Agriculture and the Florida State Plant Board have visited this area. They are making a caref ul study on the type of decline in the New Orleans area. What can we do to safeguard Florida's citrus industry?
It has often been pointed out that the State of Florida is in a vulnerable position for the introduction of insects and diseases that could result in the destruction of many of Florida's important agricultural crops. I can't urge the members of this group too strongly the necessity of cooperating with the State Plant Board and the Bureau of Entomology and Plant Quarantine, in their rigid enforcement to the letter of all existing laws and regulations. I am indeed glad to report how fortunate we are to have as a speaker at the General Session on Thursday morning, the Chief of the


PRESIDENT'S ADDRESS








FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Bureau of Entomology and Plant Quarantine from the United States Department of Agriculture, the Honorable Avery S. Hoyt. Mr. Hoyt has proved a valuable friend to Florida. I am sure the Horticultural Society membership joins me in expressing our sincere appreciation for his presence in the State and appearing on the program.
The five sections that comprise the membership of the Florida Horticultural Society, namely: the Citrus section, the Vegetable section, the Processing section, the Ornamental section, and Krome Memorial section, have as a whole experienced a very fine year. The interest of these groups have been well cared for in many lines of research. Tha Florida Experiment Station, which includes the Sub Experiment Stations, and the United States Department of Agriculture are conducting much needed research work. Florida appreciates this work and growers realize how much they have benefited in the past from completed experiments. May I throw out a challenge to the Society to lend every effort to keep this research and experiments now being conducted, driving ahead at full speed. We can keep these Institutions of service operating if we see the needed appropriations are provided.
Florida Citrus Mutual swung into operation last season. This grower organization is to be congratulated for tying ninety percent of all citrus produced in the State, under one control. This may be considered the mammoth Co-op of growers for all times. The fact that so many Florida Citrus Growers, Shippers and Processors have come together on common grounds, to pool their interest for the betterment of the industry, has benefited the Florida Citrus Industry many millions of dollars. Its successful operation has gained recognition from other fruit producing areas of the world.
The planting of citrus in Florida continues at a very rapid rate, Good prices


for fresh fruit, canned and frozen concentrate has given impetus to the wholesale planting of thousands of acres in the last eight to ten years. At this point, may I throw out a word of warning to growers who contemplate new plantings. There will come a time when you may wish you had continued to pasture that marginal land you are now preparing to plant. With a high acre return on the investment, coupled with open winters, growers seem to forget the early precautions given on the importance of "grove site selection." Are we ignoring the value of a good f fertile soil, a soil well supplied with humus that maintains moisture? A well drained soil, and one adaptable to root stock and variety. Good elevation and air drainage is essential. In 1895, "Old Man Winter" struck hard, and drove the Citrus Industry South. If we exercise good judgment, and are cautious in selecting sites for grove plantings, we will by the law of averages, develop a profitable orchard.
I believe the Florida State Horticultural Society is the leading one of its kind in the world. We members should feel proud to be associated with such a wonderful organization. The program for this session consists of seventy three subjects, with as many or more speakers. A very fine program has been arranged, and I appreciate the efforts made by the Vice Presidents of each Section in developing the programs we are to receive,
When I say we have the finest Horticultural Society in the world, there is a reason to back this statement. The existence of this Society Just doesn't happen so. Hard work over these many years by its Officers have borne fruit. This particular year, it has been my privilege as your President, to observe the Officers in action. Nineteen members of the Executive Committee, (which includes all Officers) have held eight meetings during the year in Winter Haven. Please bear in mind not a single person. receives a







REITZ: PARTIAL MOBILIZATION


penny f or services rendered, and no expenses allowed for travel. It required long trips from Miami in the South, Gainesville in the North, and f rom the East and West Coasts in attending these meetings. I have been greatly impressed with the fine spirit, loyalty to duty, and the untiring efforts of the officers and Executive Committee. Every member has performed his duties well. I have a very warm place in my heart for their splendid services.
We have four officers that do the greater part of the work in an organization of this kind. I especially wish to commend them for their fine accomplishments this year. The Secretary, Dr. Ernest L. Spencer-Bradenton; the Treasurer, Mr. Lem P. Woods-Tampa; the Assistant Secretary, Mr. Ralph P. Thompson-Winter Haven; and the Editing Secretary, Mr. W. Lacy TaitWinter Haven. We owe these men a great deal of credit. I wish I had the space to enumerate every detail these Officers executed in bringing the Society


up to its high standard. I am sure their reports will in part tell the story.
I would like very much to see the membership of the Florida Horticultural Society increased. We should have several thousand members. Florida is blessed by having a large number of intellectual growers. They would benefit the Society, and I am sure the Society would be of much value to them. We naturally trust everyone in attendance who are not members, will become members during this session. Dues from the members pay for the proceedings. If dues come in early, the proceedings can be published on time. Every member can have a part in the successful operation of the Society.
On behalf of the membership, may I express sincere appreciation to the city of Winter Haven for being host to the Florida State Horticultural Society. Our stay in your fair city will be a pleasant one. A very interesting and profitable meeting is assured.


Any attempt to assess the possible effect of an enlargement of our defense effort, and the resultant expansion of our national budget on the economic position of the Florida fruit and vegetable industry, requires assumptions on the probable magnitude of the defense program and of prospects for peace. Let us consider two major assumptions. One assumption is that we are facing a period of at least a few years in which defense activity will continue at a much higher level than in previous post-war years. Present plans call for a military f orce of 3 million men, or approximately twice as many as are now under arms. To maintain this force and provide the accompanying armaments, expenditures for"'defonse will


J. WAYNE REITZ, Provost
University of Florida College of Agriculture
Gainesville
The Korean conflict has had and will have far-reaching effects on our national economy. It has resulted in much speculation in recent months on what eff ects our increasing tempo of military preparation will have on our whole economy, including agriculture. Tonight I have chosen to join the speculators in order that we may consider some of the implications of the defense program on the economic position of Florida farmers, Ind on fruit and vegetable producers in particular .
I


PARTIAL MOBILIZATION AND
THE FLORIDA FRUIT AND VEGETABLE INDUSTRY'







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


probably reach an annual rate of at least 30 billion dollars for the fiscal year beginning next July 1. This compares with estimated expenditures of about 20 billion dollars during the current fiscal year and approximately double the amount of the previous two years. . A f further assumption is that there will be no armed conflict between major world powers. An open war between the United States and a country with the military might and productive capacity of Russia would change our defense policy from one of protection to one of survival, and, under such circumstances military expenditures, manpower and material requirements would be strained to the limitmore than ever before in our history.
Assuming, however, that our defense requirements in terms of expenditures and manpower needs will be approximately as I have outlined, let us first think of meeting these requirements and their effects on our economy in general before assessing the probable effects on Florida fruit and vegetable producers.
As we have already witnessed, the immediate effects of additional outlays for defense purposes, assuming no other governmental action, is inflationary. The Korean conflict caught us operating at or near our peacetime productive capacity. We had full employment for all practical purposes, and consumer incomes and, therefore, consumer demand soon reached an all-time high. These conditions are quite different from those prevailing in 1941 when another defense program was started. Then we had many idle resources. Under current circumstances, with no slack to be taken up, an expansion of our defense program has a doubly inflationary effect. First, increased defense expenditures mean a larger volume of money in the hands of consumers and, therefore, an increased demand for consumer goods. Second, the inaterial requirements for an expanded 'defense program must be met partially


at the expense of consumer goods, especially products of a durable nature, such as refrigerators, stoves, automobiles, radios, television sets, and housing. The full effect of each of these situations is yet to be felt. We are thus placed in a position where the buying power of consumers is increasing while the products available for purchase is declining. Under such circumstances, prices will move upward until a new equilibrium is reached between available supplies and existing purchasing power, unless the government exercises some anti-inflationary measures.
Apprehension over the effect of inserting a larger defense program into our already strained economy is not limited to economists and legislators, but is of vital concern to all. The dollar is in greater peril than during World War II or the immediate post-war years. Heroic measures will be needed to preserve its purchasing power. This accounts for the agitation for all out economic controls, and the broad control powers granted the President by Congress in the Defense Production Act of 1950.
There is a tendency, however, to overestimate the effect of an expanded defense program on the total supply of all goods, especially in view of the present level of business activity and the seemingly imminent shortages in many lines of consumer goods. The current rate of business activity and heavy consumer buying is based in part on fear that production of many lines of civilian goods will be interrupted when the defense program gets fully under way some months hence. To be sure, adjustments in production will be made involving a reduction in durable consumer goods, but bans on production seem rather remote. Recent estimates presented to Congress by the Defense Department indicate that the presently projected program of partial mobilization will require about 4 percent of our annual steel production,







REIT-Z: PARTIAL MOBILIZATION


and about 7 percent of our productive capacity of copper, and about 14 percent of our aluminum at current production rates. Such demands do not suggest a sharp diversion of our productive capacity into military channels or that civilians will face a serious problem of adjustment to lower consumption levels. However, when the full level of military expenditures is reached, the impact on prices will continue to be inflationary even though increased production of military goods will represent but a small part of the total national productionnow at an annual rate of some 270 billion dollars.
Under prevailing economic conditions, and the impact of an expanded defense program, f ruit and vegetable producers can look forward to a continued high level of demand for their products during the next few years. The demand for many fruits and vegetables will be bolstered by increased Government purchases to meet the food requirements of a larger armed force. During the last war we found that the consumption levels of luxury type foods such as meats, dairy products, and many fruits and vegetables were considerably higher among service personnel than among civilians. As a result, we can expect the consumption rate of many of our products to increase with the expansion of our armed forces. The effects of increased military purchases should be more noticeable in the canned and frozen food field, since a high proportion of such purchases will be in this form.
Much more important than the increased consumption of our armed forces is the indirect effect of antiinflationary controls on demand for f ruits and vegetables and the great bulk of other farm products. We have noted already that increased production f or defense purposes places more purchasing power in the hands of consumers. For the eqonom r in general, the inflationary


eff ects thereof can be counteracted by credit restrictions, calling for higher down payments and shorter payment periods. Yet credit controls tend to increase the demand for farm products. Such controls make it impossible for large numbers of consumers to obligate their future earnings through installment buying. Thus, they are simply taken out of the market as buyers of durable goods and housing. The result is that the housewife has more dollars available for buying f ood, particularly the so-called luxury items, such as meats, green and leafy vegetables, and fruit juices. However, it should be borne in mind that the full effects of such controls will not be noticeable for some months.
Now let us turn to production problems arising f rom partial mobilization. There seems to be little reason to expect any pronounced production difficulties under the assumptions made. I have already indicated that the requirements of our basic metals for defense purposes will not be excessive. It does not appear at this time that there will be any serious shortages of farm machinery. Should shortages develop, the Government, no doubt, would hasten to assure adequate production through allocating critical materials to specific industries. Fortunately, the quality and condition of machinery and equipment on Florida farms are excellent.
Critical shortages of insecticide materials are not likely, although some substitution may have to be made for some chemicals which require large amounts of chlorine. Fertilizer supplies should be adequate to meet normal usage and production requirements. To be sure, nitrogen will be required to produce ammunition for training purposes and for stock-piling, but demands for such purposes should represent a comparatively small proportion of our total output and should not be great enough to affect the supplies available for agricultural production, Furthermore, much of the







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


great capacity f or nitrogen production developed during the war years is not in use at the present time.
Some manpower shortages will develop as a result of an increase of one and a half million men in the armed forces along with demands for labor in producing armaments. But such shortages should be felt least of all in the field of agriculture. While the effects of the draft or enlistments on available labor supplies will be equally distributed throughout the economy, the increased demand for civilian labor will be confined largely to the industrial areas of the North. We should also bear in mind that a part of our defense production will be at the expense of goods f or civilian consumption, and that the increase in our labor requirements will be somewhat less than proportionate to the expansion of the defense program. Under such circumstances, and based on our previous assumptions, Florida f ruit and vegetable producers should not face serious labor shortages. I might add, however, that as a precaution against a real emergency, steps should be taken to provide for labor-saving techniques and equipment.
I mentioned the broad control powers granted the President in the Defense production Act passed in the recent session of Congress. Failure to exercise these powers to the fullest has been the subject of much criticism. Discussion of controversial subjects often develops more heat than light, and this is no exception. The chief clamor has been for wage and price ceilings, and, if necessary, consumer rationing. Price controls may make practical politics, but are almost certain to have an undesirable effect on our productive effort and on the defense program. In times of stress we are inclined to forget the real function of price in our capitalistic economy. We fail to remember that price is the one and only guide of the producer, that


price is the means by which available supplies of goods are apportioned among consumers, so that the amount .-which people wish.to buy is just equal to that which people wish to sell.
As yet, we have failed to find or devise a means of achieving the delicate balance that is inherent in the price mechanism on a f ree market. In attempting such operations, some prices are fixed too low so that production is discouraged and consumption is increased; the result: a virtual disappearance of the affected commodity f rom the market. On the other hand, some. prices are fixed too high, so that consumption is discouraged while production is increased; and the result in this case: the accumulation of surplus supplies. Our experience with price controls during the last war, particularly on perishable agricultural products, indicate that we cannot duplicate or replace the pricing mechanism, and that we cannot achieve a balance between production and consumption without a f ree market price.'
This is not to say, however, that we should do nothing about the general level of prices. No responsible person can be complacent about the dangers of inflation. We have means by which the general level of prices can be controlled without taking on the almost hopeless task of replacing the pricing mechanism with a price control program.
If we earnestly desire to check inflationary tendencies we c ' an do so by the Federal Government adopting proper fiscal policies. This can be done by the simple expedient of controlling the quantity of money people have to spend through the use of credit restrictions or increased income taxes, preferably both. Direct credit restrictions, such as those currently in effect on durable goods and housing, reduce- the level-of effective demand for suchzproducts. If made increasingly stringent,. consumer,, buying power will-be redacod to the point I of









































CITRUS SECTION



THE EFFECT OF 2,4-D ON PRE-HARVEST DROP OF I CITRUS FRUIT UNDER FLORIDA CONDITIONS


GARDNER, REECE AND HORANIC: PRE-HARVEST DROP


bringing about price declines. Other effective curbs on credit can be accomplished through regulations imposed on the banking system, through the facilities of the Federal Reserve System.
The possibilities of increasing taxes to check inflationary pressure has been recognized by the present administration and the realities thereof will be apparent when the monthly pay check comes in tomorrow. Increased income taxes not only reduce consumer buying power, but avoid the inflationary effects of deficit financing through the media of Treasury bonds. Yet, as an anti-inflationary measure, taxation has the fundamental disadvantage of being extremely unpopular. As a result, it is difficult politically to increase the taxation rate to the extent necessary to affect consumer demand and in turn the general level of prices. It is doubtful, therefore, if we shall have the fortitude to put partial mobilization on a


pay-as-you-go basis, and consequently the net effect will be inflationary.
To summarize, the over-all effect of partial mobilization on the Florida fruit and vegetable industry will be to provide a stronger demand for products than would otherwise exist. Production costs will increase, but no serious shortages are expected in materials and labor. There is nothing in the current or future situation to warrant price controls or consumer rationing. If they appear to be needed, the best method of handling is by controlling the general price level through tightening over-all credit controls and increased taxation rather than by interfering with the pricing mechanism.
How far we shall go in credit controls or taxation I do not know, but of this I am sure; if we do the job which is now before us-as it should be done-our sacrifices are going to have to match our hopes and aspirations for peace.


F. E. GARDNER, PHILIP C. REECE AND
GEORGE E. HORANIC
Bureau of Plant Industry, Soils, and Agricultural Engineering, United States Department of Agriculture
Orlando
Pre-harvest drop of citrus fruit during-some seasons reaches a high percentage of the total crop in certain varieties. Midseason varieties, such as Pineapple and seedling sweet oranges, are generally considered the most prone


to heavy pre-harvest dropping. Periods of warm, dry weather during the fall and winter months favor fruit shedding. Losses from this cause may constitute as much as one-third of the total crop and are rarely less than 15 percent. The Valencia variety is not considered such a bad dropper, and indeed fruits rarely fall in such large numbers within a short time as is frequently observed with Pineapple orange near the end of its maturity season. However, the drop extends over a much longer period in







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


the case of Valencias, so that the total losses in this variety also may be very heavy. The rapid decay of grounded fruit and also the covering-up of such fruit from time to time by grove disking serves to hide from the grower the magnitude of the losses during a prolonged dropping period.
Following the successful use of naphthaleneacetic acid and naphthaleneacetamide to control pre-harvest drop of apples (3), it was reported by Gardner in 1941 (1) that these compounds also could be used to materially lessen the drop of Pineapple oranges in Florida. However, the relatively high concentrations required and the fact that the materials were not found to be effective applied later than November, made the discovery of doubtful practical value. More recently the findings of Stewart and his associates in California have shown that 2,4-D is much more potent in controlling the drop of citrus fruits and, as a result, its use is gaining wide acceptance in that State. Stewart and Klotz (4) sprayed Valencia orange trees in May with a 2,4-D derivative (diethanolammonium 2,4-dichlorophenoxyacetate) in concentrations of from 5 to 40 p.p.m. and reported a decrease in fruit drop, compared with the controls, of up to 55 percent at 40 p.p.m. On Marsh grapefruit Stewart and Parker
(5) used the same compound in June in concentrations of 5, 25, 75, and 225 p.p.m and obtained nearly as good con-


trol with the two lower concentrations as with the higher ones; both of the latter caused rather severe foliage damage. It should be noted that the sprays applied in May and June are just prior to harvest period of these varieties in California. The trees at this time would be in a very active condition. This situation will be referred to later, as it may have a bearing on the divergent results secured in the studies here reported with sprays applied in the fall and winter months.

1948 Experiments
Sprays of 2,4-D and several other hormone compounds were applied to Pineapple and Valencia oranges. Trees were chosen for their comparable size and crop in blocks of six. Blocks were replicated ten times and within each block the following six treatments were applied to single-tree plots: (1) 2-methyl 4-bromophenoxyacetic acid; (2) 2methyl phenoxy alpha-butyric acid; (3) 2-methyl 4-chlorophenoxyacetic acid;
(4) sodium salt of 2,4-D, all four materials being applied as sprays at concentrations of 20 p.p.m. of 2,4-D acid equivalent; (5) isopropyl ester of 2,4-D incorporated with dusting sulphur and used as a dust, also at the rate of 20 p.p.m. of 2,4-D; (6) control plots receiving no spray or dust.
Sprays were applied on October 15 by a ground crew with conventional highpressure rig. Thorough coverage was


TABLE 1.
THE EFFECT OF SEVERAL HORMONE COMPOUNDS ON PRE-HARVEST DROP OF CITRUS.


Treatments Applied October 15, 1948 Conc. 20 p.p.m. Free Acid Equiv. 2-meth. 4-chloro phenoxyacetic 2-meth. phenoxy alpha-butryic 2-meth. 4-bromophenoxyacetic 2,4-D (isopropyl ester) in sulphur 2,4-D (sodium salt) Control


Pre-harvest Drop in Percent of Total Crop Applied Valencia
As Pineapple (+Splits) (-Splits)
Spray 24.3 37.4 30.9
Spray 26.2 43.5 31.1
Spray 25.1 36.2 28.3
Dust 21.31 28.7 21.4
Spray 16.31 36.4 28.8
---.---- 28.6 32.3 24.3


'Statistically significant. Difference between means of 6.9 required for significance at 1% level.


















































TABLE 2.
THE EFFECT OF 2,4-D WITH AND WITHOUT SULPHUR ON PRE-HARVEST DROP OF PINEAPPLE AND VALENCIA ORANGES.
Drop in Percent of Total Crop
Pineapple Valencia
Treatments -Sprays Applied December 19, 1949 Picked Feb. 13 Picked May 5
Control-(no spray) 16.8 14.7
Control-wettable sulphur only 18.7 15.4
2,4-D at 25 p.p.m. 6.81 17.9
2,4-D at 25 p.p.m. with sulphur 6.11 17.4
2,4-D at 50 p.p.m. 4.01 19.8
2,4-D at 50 p.p.m. with sulphur 5.3' 14.0
'Statistically significant. Difference between means of 5.88 needed for significance at the 11o level.


GARDNER, REECE AND HORANIC: PRE-HARVEST DROP


obtained with 15 gals. of spray per tree. Temperatures during the time of application ranged from 740 to 820 F. The dust treatments were applied on October 19, a still day on which the temperature varied from 74' to 77' F. All previous drops were removed from beneath the trees and subsequently all drops were gathered and counted, beginning November 1 and at weekly intervals thereafter until the crops were harvested, the Pineapple oranges on February 14 and the Valencias on May 4.
The first three compounds listed in table 1 had previously been found to be very effective (in a class with 2,4-D) in delaying abscission of Coleus petiolesa test used by Gardner and Cooper (2) to screen a large number of compounds for effect on abscission. It is. evident that none of the three had any influence in controlling the drop of either of these orange varieties. The data in table 1, however, serve to show the very heavy fruit drop frequently encountered in Florida citrus, and that 2,4-D applications effected an appreciable control of this drop in Pineapple oranges but not in Valencias. The reduction in drop of the Pineapple oranges with the 2,4-D spray amounted to 43.1 percent of the drop from the control trees. The dust application was less effective, due probably to the poor-


er coverage than can be.obtained with sprays.
Fruit splitting in the Valencias was quite severe during the fall and winter of 1948 in this test grove and there ore all Valencia drops were separated as to split and sound fruit and counted separately. The subtraction of splits from the total drops as presented in the Valencia section in table 1 did not alter the conclusion that 2,4-D had no effect on drop in this variety. Neither was there any influence of this compound on the amount of splitting.

1949 Experiments
Because of the frequent use of wettable sulphur sprays in Florida for rustmite control, it was important to learn if 2,4-D could be added to such sprays instead of making a separate application. The 1949 experiments were designed to test this point, as well as to investigate the possibility of higher concentrations of 2,4-D. Both Pineapple and Valencia varieties were included in these tests, which included 6 treatments with 10 replications. The 2,4-D (sodium salt) Was used at 25 and 50 p.p.m., both with and without wettable sulphur (10 lbs. per 100 gal.) Dual control treatments were set up consisting of (a) no spray and (b) sulphur only.
Table 2 discloses a very appreciable







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


and highly significant reduction of fruit drop in the case of Pineapple oranges at both concentrations of 2,4-D. The higher concentration (50 p.p.m.), while appearing to be the more effective, is not significantly so, and the use of this high concentration would not seem justified. In this experiment the use of 25 p.p.m. resulted in a saving of 1.7 boxes of fruit per tree, compared with the average drop of the controls.'
It is evident f rom table 2 that 2,4-D can be combined with wettable sulphur without loss of effectiveness. Apparently there is considerable leeway in the timing of the 2,4-D application (October, November, or December) and combining it with wettable sulphur will rarely present interference with the timing needed for rust mite control.
The 1949 trials with 2,4-D, like those in 1948, were without effect on Valencias. These results are in marked contradiction to those reported from California with this variety. Until more work is done with Florida Valencias, the reason for this disagreement in results can only be surmised. Trees sprayed in May or June in California are in a much more active condition than the trees in Florida that were sprayed in the f all and winter. It is possible that the difference in time of spray application is responsible and that earlier application would be effeetive in Florida. If this is the correct explanation, it is strange that the Florida Pineapple trees respond so markedly to 2,4-D at any time during their dormant period.
Effect On Other Varieties
Sweet seedling oranges, Temples, and Marsh grapefruit were also sprayed in

A concentration of 25 p.p.m. of 2,4-D was made by adding 2.1 oz. of the commercial sodium salt (83 percent 2,4-D equivalent) to 500 gal. of spray. Because it is readily soluble in water, it was added directly to the spray tank and agitated briefly before application.


1949. The treatments consisted of controls and 2,4-D sprays at 25 and 50 p.p.m. without wettable sulphur. Each treatment was applied to single-tree plots with 10 replications. Unfortunately, picking crews harvested the crops without notifying the experimenters and thus no record of the amount of crop on the trees at picking date was obtained on which to base percentages of drop. With only the week-by-week pick-up record of dropped fruit from the sprayed and non-sprayed trees, no definite statement can be made as to the effectiveness of the sprays on these three varieties. The partial data, however, suggest that 2,4-D was reasonably effective on sweet seedlings and Temple oranges but was not at all effective on Marsh grapefruit.

Injury To Citrus From 2,4-D
Fall and winter applications of 2,4-D at a time when young growth is not present and not anticipated for some weeks to come, have not resulted in any observable effect on the foliage on the tree at the time. In the following spring when new foliage appears there are nearly always a f ew leaves to be f ound that show 2,4-D eff ects. This is true almost regardless of the weakness of the concentration used. The deformed leaves are few in number and may not appear except on occasional trees, and they are not cause for alarm.
The lack of damage from low concentrations of 2,4-D should not lull the grower into the belief that high concentrations can be safely applied to or around citrus. A disastrous instance was observed in which 2,4-D at 1000 p.p.m. was applied to eradicate a dense stand of Callicarpa americana, growing as a weed in a block of Pineapple oranges on Rough lemon roots. The application was made in midsummer and care was taken to avoid spraying the trees directly. A heavy rain shortly thereafter







WANDER AND REITZ: COMPOSITION OF IRRIGATION WATERS


washed the 2,4-D down to the Rough lemon roots and resulted in severe damage and eventual death of the trees. The same weed in another grove nearby was treated in the same manner with the same spray and on the same day. This grove was on sour orange roots and in somewhat heavier soil. It escaped any visual damage. Presumably the difference in response can be attributed chiefly to the difference in rootstock,-the Rough lemon apparently being more sensitive than sour orange.

Acknowledgments
We wish to express our thanks to the Chase Investment Company at Windermere, Florida, for their generous cooperation and assistance in applying the


sprays for the Pineapple and Valencia tests. Our appreciation is also extended to Mr. G. F. Randall of Orlando for permitting the use of his groves for certain of the experiments.
LITERATURE CITED)
1. GARDN~Ln. F. E. Practical applications of plant growth substances in horticulture. Proc. Fla.
State llort. Soc. 54: 20-26, 1941.
2. GAsRDNEss, F. E., and CoopERn, W. C. Effectiveness of growth substances in delaying abscission of Coleuis petioles. Bot. Gaz. 105: 80-89, 1943. 3. GARDNER, F. E., MARTH, PAUL. C., and BATJER, L. P. Spraying plant growth substances for control of the pre-iarvest drop of apples. Proc.
Amer. Soc. Host. Sci. 37: 415-428, 1939.
4. STEWART, W. S., and KLOTz, L. J. Some effects of 2,4-dichlorophenoxyacetic acid on fruit drop and morphology of oranges. Bot. Gaz. 109:
150-162, 1947.
5. STEWART, W. S., and PARKER, E. R. Preliminary studies on tlse effects of 2,4-D sprays on preharvest drop, yield, and quality of grapefruit.
Proc. Arter. Soc. Hart. Sci. 50: 187-194, 1947.


THE CHEMICAL COMPOSITION OF IRRIGATION
WATER USED IN FLORIDA CITRUS GROVES


1. W. WANDER AND'H. J. REITZ
Cit rus Experiment Station
Lake Alfred

A knowledge of the chemical composition or mineral content of irrigation water is of great importance to growers because of the known detrimental effects to plants of highly mineralized water. Although water from various sources has been used for irrigating citrus in Florida for many years little is known of the actual chemical composition of much of the water which is used. A report made 50 years ago indicated damage to citrus when irrigated with artesian well water (9). A more recent report (14) indicated that many wells in several East Coast districts were increasing in salt content thus increasing the possibility of damage when used on groves. Similar increases in saltiness have been experienced with municipal water supplies for several coastal cities (8) (10).


In most areas where irrigation is required, the annual rainfall is generally low. Such conditions result in accumulations of salts in the soil, because there is little or no loss of the salts through leaching by rainfall. Since practically all of the citrus growing area of Florida receives annually 50 to 60 inches of rain (4) accumulations of salts are not likely to occur from year to year. Leaching of applied salts is also aided by the f act that most of the soils on which citrus is growing in Florida is of a very sandy porous nature and easily leached. Since these soils contain practically no clay which exhibits exchange capacity, additions of sodium from salt water does not destroy their structure thus impeding leaching as often happens in many regions using irrigation.
For these reasons the use of irrigation water on citrus in Florida presents a different problem than found in many other citrus growing areas. In fact,







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


transport water samples to the laboratory for analysis. An effort was made to obtain samples from wells which were in use, since it is known that a lower mineral content is often found in wells which have not been used for several weeks or months. After the well has been in use for several hours the mineral content becomes relatively stable.

Methods of Analysis
The methods of analysis used were of a type primarily fitted to water analysis. Several of the methods are relatively recent developments and will be mentioned briefly.
pH measurements were made using a glass electrode.
Specific conductance was measured in mhos x 10 - 5 at 25'C. This measurement is directly related to total dissolved solids in the water.
Calcium was determined by titrating an aliquot of the water with versene (disodium dihydrogen ethylenediamine tetracetate dehydrate) using ammonium purpurate indicator (2) (6).
Magnesium was measured by titrating a portion of the water with versene using errochrome black T indicator which gives a value f or the total magnesium and calcium present. By subtracting the amount of calcium previously found the magnesium concentration can be found
(2).
Sodium was estimated through the use of a flame photometer (1) (12).
Chloride concentration was found by titration with mercuric nitrate using diphenylearbazone bromophenol blue mixed indicator (3).
Sulfate content was measured by precipitation under controlled conditions with barium chloride and reading the resultant turbidity with a photoelectric colorimeter (11).
Carbonates and bicarbonates were estimated by titration with standard sulfuric acid using phenolphthalein indicator for


water containing greater amounts of salts can be used under the climatic and soil conditions found in Florida than could be used if the climate were drier and the soils heavier. This was pointed out in work done by Young (15) using known concentrations of sodium chloride solutions on citrus seedlings growing in pots in the greenhouse. He concluded that relatively high concentrations of sodium chloride alone were not detrimental to growth.
Previous analysis of irrigation waters
(14) involved only the determination of the chloride content and a calculation to the equivalent amount of sodium chloride. Some preliminary work with water samples taken in 1949 showed that the amounts of sodium found were not sufficient to account for all the chlorides present, thus indicating the presence of other minerals such as calcium and magnesium chlorides. This is to be expected because the mineral composition of the water will be deter-, mined by the minerals dissolved from the rock and mineral deposits through which it passes plus that contributed from any infiltration by sea water. Several reports (5) (10) have listed the chemical constituents found in waters from different Florida localities. Most of these analyses are for municipal water supplies and relatively less information is available giving data related to irrigation supplies.
Thus, for several reasons, a more complete picture of the composition of water used for irrigation was felt desirable in order to more correctly evaluate such water. It is the purpose of this report to list the composition of waters from widely different localities which are used for irrigating or for mixing sprays for citrus.

Collection of Samples
Clean quart mason jars fitted with a jar rubber and glass top were used to







WANDER AND REITZ: COMPOSITION OF IRRIGATION WATERS


tainted directly in parts per million. This relationship is the same as found in other areas of the United States where water analyses are made (13). Since the specific conductance of a water sample is very easily obtained (comparable to the time required for a soil pH determination) it can be seen that such a measurement is of great value in rapidly evaluating a water source. It is probably the best single index for deciding the advisability of using water for irrigation in Florida.

Average Chemical Composition of Water from Nine Florida Counties
The maximum, minimum and average amounts of the various elements determined along with pH, total dissolved solids and calculated amount of sodium chloride in water from several localities is given in Table 1. The sodium chloride


the carbonate endpoint and methyl purple for the bicarbonate endpoint (7).
A qualitative analysis of several of the wells containing the largest amounts of dissolved solids was made by a spectrographic procedure.

Relationship of Specific Conductance
and Total Dissolved Solids
Twenty-four water samples representing the East Coast, West Coast and Central Florida were evaporated to dryness and the resulting salts weighed. The total dissolved solids in parts per million thus determined were compared to specific conductance values obtained with a conductivity meter. Fig. 1. The relationship was found to be directly proportional and if the specific conductance in mhos x 10 - I at 25'C. is multiplied by 7 the concentration of soluble salts is ob-


IOW Z000 _7566 4010-0 _5 00 6000 7000 8do
PPM TOTAL. DISSOLVED -SOLIDS

Fig. 1. Relationship between parts per million total dissolved solids and
conductivity measurements of irrigation water.








FLORIDA STATE HORTICULTURAL SOCIETY, 1950


content is given simply for a basis of careful consideration of local conditions
comparison with previously published and if a new well is to be drilled a geolofigures. As previously mentioned it does gist familiar with local conditions should
not represent a true picture, however, be consulted. Further study of this table
since all the chlorides found cannot be reveals the great variation between loassumed to be sodium chloride. calities in water composition. For exFrom this table it can be seen that ample on the mainland of Brevard
individual wells within the same locality County there was on the average 1283
vary considerably in mineral content. p.p.m. of chloride ion and 107 p.p.m. of
This is to be expected because all wells sulfate ion whereas in Sarasota County
are not at the same depth and conse- there was only 202 p.p.m. of chloride ion
quently tap different water strata. This as compared to 836 p.p.m. of sulfate. In
great variability stresses the need for one case the water was primarily chloride

TABLE 1.
MAXIMUM, MINIMUM AND AVERAGE COMPOSITION OF WATER FROM INDEX WELLS IN NINE FLORIDA COUNTIES IN 1950.

No. Parts Per Millin
Locality Samples pH T.D.S.2 Na Ca Mg C1 So, CO., 11C05 NaCi

Brevard Co. Max. 8.40 15000 4800 514 635 7745 1200 14 15 12768
Islands Mini. 7.50 763 110 62 27 225 34 0 7 371
57 Aver. 8.20k 3106 688 170 108 1432 203 8 105 2349
Brevard Co. Max. 8.40 7217 2100 269 223 3872 230 16 156 6383
Mainland Mini. 7.65 1484 269 76 39 605 0 0 7 997
10 Aver. 7.95 2580 624 132 87 1283 107 5 94 2116
Indian River Co. Max. 8.40 1442 260 96 68 527 230 16 159 870
Min. 7.30 833 124 47 46 225 38 6 99 371
38 Aver. 7.79 1099 179 64 57 371 106 12 133 607
St. Lucie Co. Max. 8.30 3570 869 116 110 1494 384 25 299 2463
Min. 7.30 714 90 37 23 151 48 6 90 249
55 Aver. 7.81 1528 295 72 59 538 138 13 137 887
Pinellas Co. Max. 8.40 2280 590 246 67 1626 120 19 228 2681
Min. 6.98 168 9 22 2 18 0 0 10 30
21 Aver. 7.54 887 129 70 25 296 .30 9 143 488
Manatee Co. Max. 7.85 2430 360 289 116 822 590 19 164 1356
Min. 7.35 441 0 60 28 18 137 0 35 30
26 Aver. 7.60 10431 58 151 66 162 387 6 129 272
Sarasota Co. MIax. 8.20 2280 245 463 152 520 1526 16 170 857
Mini. 7.35 644 24 78 50 311 295 0 84 50
14 Aver. 7.54 1314 60 255 96 2012 8;36 5 121 33
Charlotte Co. Max. 8.60 5240 1180 241 195 2109 771 16 145 3477
Mini. 7.20 1010 158 67 45 302 48 0 48 499
11 Aver. 7.67 2485 468 150 9)3 975 302 6 100 1607
Lee Co. Max. 7.80 2580 530 130 101 974 379 16 180 1605
Mini. 7.30 1554 270 71 61 457 240 0 96 754
9 Aver. 7.59 2185 411 102 87 774 305 11 145 1276
Polk Co. Wells Max. 7.65 221 8.1 37.2 7.1 9.6 2.4 0 144 16
Min. 7.40 168 5.5 29.2 5.6 6.2 2.4 0 108 10
2 Aver. 7.52 194 6.8 33.2 6.4 7.9 2.4 0 126 13
Polk Co. Lakes Max. 7.20 98 9.0 6.4 5.3 18.8 31.2 0 22.6 31
Mini. 6.55 35 5.1 1.4 2.6 9.6 16.8 0 3.1 16
9 Aver. 6.93 69 7 4 3 14 23 0 13 23

Arithmetic mean of individual values.
Total dissolved solids calculated from conductivity.







WANIER AND REITZ: COMPOSITION OF IRRIGATION WATERS


itC0- C1 C10C10uL-1
M '-, N In C


cq c0i 1 -i1


00 14 C 00 M M0 C11 =0 1


N - 1: ' 1-4 N N 100-1


M * 6 1 h1t: ! A0


00 M q 4 r:'- M


0 1i C 00q
t-C110 ini 1V'


U, 6 ,30 '1"c:


U b0O: ML qN NC5Nt t


00k iC -! 1i~ 00 C 00 C 01: Z=$0-40 =(







O O0 4.C 0 )

Cd C


and in the other primarily sulfate. Further inspection shows the much greater mineral concentration in water from both coastal regions as compared to deep wells in the inland district of Polk County. As might be expected the lowest concentration of salts is found in the lakes of Polk County.
Another perhaps more easily understandable way of expressing the mineral content of water and resultant addition of salts when added to the soil as irrigation is given in Table 2. This table gives the pounds of various salts added to an acre of soil when that acre is irrigated with one inch of water containing the average mineral composition for the particular locality in question. If for example you applied an irrigation of two acre inches using the maximum water found in Sarasota County you would have added to that acre 414 pounds of sodium chloride, 162.8 pounds of magnesium chloride, 50.6 pounds of magnesium sulfate, 307.4 pounds of calcium sulfate, 14.1 pounds of calcium carbonate and 62 pounds of calcium bicarbonate or a total of 1021 pounds of these various salts. When it is realized how much material can be added through irrigation the importance of not letting a grove get dry after irrigation is readily understood. If 1000 pounds of soluble salts were evenly distributed through the first 2 feet of an acre of the average sandy soil by an irrigation, the soil would contain 125 p.p.m. of soluble salts. However, the average sandy soil will hold only 5 percent water so that the soil solution at field capacity will contain 2500 p.p.m. soluble salts. If the soil moisture drops to 1 percent the soil solution will contain 12,500 p.p.m. soluble salts which is high enough to injure most plants. Once irrigation is started with water containing considerable soluble salts the soil should never be permitted to become low in moisture at least until after a good leaching rain. I












































TABLE 3
CHANCES IN SALT CONCENTRATION (CALCULATED AS P.P.M. NaCI FROM C1 CONTENT)
IN INDEX WELLS IN THE INDIAN RIVER AREA


FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Trend in Salt Concentration of
East Coast Wells
Table 3 records the changes found in wells from several East Coast areas from the period 1942 to 1950. More wells were sampled from 1944 to 1950 and that data is included separately. In eight out of eleven areas sampled from 1942 to 1950 there was an increase in salt concentration. With more samples taken from 1944 to 1950 six areas out of 12 showed an increase while the other six areas decreased. In all cases the increase or decrease was slight and the trend either way was related to a definite region. For these wells it would appear that changes take place rather slowly.

Other Elements Found in Water
One of the objectives of this investigation was to determine what other elements might be present in addition to the usual constituents. Examination by spectrographic means of residues from 16 wells showing the highest concentration of soluble salts revealed considerable amounts of strontium present in all samples. A quantitative analysis of one


sample showed approximately 30 p.p.m. strontium present. The effects of strontium on citrus are not known but it is known to be toxic to some plants. Experiments have been started to estimate its, effect on citrus. No barium, potassium, or lithium was present in the samples examined although these elements are often present in natural waters.

Summary
1. The total soluble salts present in an irrigation water is probably the best single index to use in evaluating the water.
2. The climatic conditions and soil types in Florida permit the use of water containing greater amounts of soluble salts than is ordinarily considered safe.
3. It is essential that, when irrigating with a high mineral content water, the soil moisture is maintained as high as practical.
4. Individual wells in the same area vary considerably in soluble salt concentration and different areas vary as to the type of soluble salts present.
5. Strontium was found in the water


-57 Wells Sampled from 1942
to 1950


88 Wells Sampled from
1944 to 1950


Locality


Brevard Mainland Courtenay Merritt-Indianola Georgiania-Footman Lotus
Tropic
Oslo
N. W. Vero Beach S. W. Vero Beach Ft. Pierce Farms Ft.- Pierce Vicinity White City


1950

1587

2162 1771 1533 1058 502 592 592 673 629 967


No.
Wells 1944 1947


1942 1944 1235 1320


1947

1360

2120 1657
1540 1080 488
641 655 720 613 1010


1950

1370 6080 2170 1771
1494 1029 502 609
604 658 620 967


3 1263 3 5712 19 2134 6 1765 10 1481 3 1068
4 486 11 611 13 630 8 703 .6 633 2 1015


1250 6227 2155 1657 1527
1047 488 625 650 669 632 1010


2123 1668 1331 875
465 539 598 683 576 1003


2105 1765
1472 1138
486 614 646 750 627 1015







GUNTER: GROUND WATER RESOURCES


from wells on both the East and West Coasts of Florida and may or may not present a hazard to citrus.
6. The increase in saltiness of wells on the East Coast is slow and confined to certain districts.

LITERATURE CITED
1. BERRY, j. W., D. G. CHKAPPELL, and 11. B.
BARNES. Improved method of flame photometry.
Ind. Eng. Chem., Anal. Ed., 18:19. 1946:
2. BETZ, J. D., and C. A. NOLL. Total hardness is
water by direct colorimetric titration. Jousr.
Amer. Water Works Assoc. 42:49-56. 1950.
3. CLARKE, F. E. Determination of chloride in
water. Anal, Chsem. 22:553. 1950.
4. Climate and Man. Yearbook of Agriculture.
pp. 809-818. 1941.
5. COLLI~NS, W. D., and C. S. HOWARDo. Chemical
character of waters of Florida. Dept. of the Interior. Water Supply Paper. 596-G. 1927.
6. DiEHL, H., C. A. GOETZ, and C. HAcit. The
versenate titration for total hardness. Jour.
Amer. Water Works Assoc., 42:40-48. 1950.


7. Official and Tentative Methods of Analysis.
A.O.A.C., p. 640, 6th Ed. 1945.
8. PARKERS, G. G. Salt water encroachment in
Southern Florida. Jour. Amer. Water Works
Assoc. 37:526-542. 1945.
9. ROBSINSON, M. R. Report on fertilizers and
irrigation. Proc. Fla. State Ilort. Soc. 13:140145. 1900.
10. STmINOFIELD, V. T. Ground water resources of
Sarasota County, Florida. Twenty-third, twentyfourth annual report. Fla. State Geological
Survey. P. 176. 1930-32.
11. TREON, J. F. and W. E. CRUTCHTFIELD, JR.
Rapid turbidimetric method for determination of sulfates. Ind. Eng. Chsem., Anal. Ed. 14:119.
1942.
12. WEST, P. W., P. FOLsE, and D. MONTGOMERY.
Application of flame spectrophotometry to water
analysis. Anal. Chsem., 22:667. 1950.
18. Was~cox, L. V. Explanation and interpretation
of analysis of irrigation water. U.S.D.A. Circular
No. 784. May 1948.
14. YOUNG, T. W., and V. C. JAMISON. Saltiness in
irrigation wells. Proc. Fla. State Hort. Soc.
1944.
15. YOUNG, T. W. Florida Agricultural Experiment
Station. Annual Report. P. 288. 1949.


GROUND WATER RESOURCES OF FLORIDA


HERMAN GUNTER
Florida Geological Survey
Tallahassee

Introduction
All -life depends upon water for its very existence. As an essential to human life,-water is second only to the air we breathe. It is therefore the more deplorable that this commodity on which our existence depends continues to be wastefully and unwisely used with either complacent disregard for, or no thought of, the consequences of such practices. Periodic deficiencies brought about by droughts, by local overdevelopment or by occasional breakdown of the water supply system may tend to impress upon us the importance of an adequate water supply, but as soon as our temporary inconveniences are removed we again fail to exercise discretion in protecting our water resources. Water is the most valuable and priceless resource that any commun-


ity, county or state possesses. The shortage recently experienced by New York City has quite forcefully focused attention upon the necessity of an ample water supply, and this has had a stimulating influence on Nation-wide thinking about water resources.
In regions like Florida blessed with generous rainfall and with formations adapted to storing it, there is at least more reason for the prevailing general idea-and often firm conviction-that water supplies are inexhaustible and may be used or cast away without concern as to the effect on future supplies. Yet even in these regions where provident Nature has been extremely generous, there is evidence of an increasing concern about the adequacy and permanence of water supplies. This awakening has come about gradually the hard way-by actual experience. With rapid increase both inf population and in industry greater and greater demands for water are







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


made, and in supplying these increasing demands arresting problems have arisen.
Everyone should realize that water is an exhaustible resource and should in all uses treat it accordingly. In providing water there should be rather clear ideas as to the source to be tapped, the development of the well field, the movement of water underground into the area, and the general character of water that may be obtained. With the accumulation of such information and the assimilation of such data it is possible to more intelligently and satisfactorily locate wells, let contracts for drilling, develop the supply,


and guard against contamination as well as possible infiltration of salt water.

Source of Our Water Supply
A very general and popular explanation of the source of artesian water in Florida is that it originates in the mountainous regions of states to the north, and in spite of all that has been said through the years to the contrary, this idta still persists. Except for those portions of the State bordering Georgia and Alabama, all the ground water in Florida comes from rainfall within the State, and even in northern and western Flor-


EXPLANATION-Contour lines represent approximately the height, in feet, to which water will rise with reference to mean sea level in tightly cased wells that penetrate the principal artesian aquifer. Contour intervals 20 feet. Stippling Indicates area of flowing wells.


Plate I. Map of Florida Showing Piezometric Surface of Main Artesian Aquifer
. and Area of Flowing Wells.







GUNTER: GROUND WATER RESOURCES


structure of rock formations, all of which influence the accumulation, rate of movement and direction of flow of water under ground. Let us consider briefly the geology of Florida, and limit the discussion to those formations most important to water supply.
All of the surface or exposed formations in Florida are included within the latest major division of geologic time, termed the Cenozoic Era, meaning more modern time. In Florida there is complete representation of each series in this era from the oldest to the youngest. The most important of these in relation to water supply are: 1) the Eocene, including the Ocala and older limestones, 2) the Oligocene, mainly the Suwannee and Marianna limestones, and 3) the Miocene, of special interest because of development in peninsular Florida and the local names of Tampa limestone and Hawthorn formation. Also the more recent Pliocene and Pleistocene formations, since these are of importance, especially in western Florida and along the lower East Coast.
The principal artesian water formation, or aquifer, is the Ocala and the older Eocene limestones. Itisfromthese limestones that the great volumes of water are derived in peninsular Florida. In earlier literature the Ocala limestone was mistaken for the Vicksburg limestone, named from its typical exposure at Vicksburg, Mississippi. This name is still applied incorrectly by some citizens of the State, although the term Ocala limestone has been used many, many years, and has here replaced, the term "Vicksburg" in scientific usage. Well drillers are familiar with the Ocala limestone and are quite proficient in determining when it has been penetrated, since the limestone is usually fairly soft, granular and white to . cream-colored, often full of fossils. These Eocene limestones are known to underlie all.of Florida with the possible exception of the


ida the ground water originates in local rainfall, but here it is supplemented by contributions from southern Georgia and Alabama through contiguous surface and subsurface formations. The formations in the northern mountainous regions are vastly different in age and character f rom those at or near the surface in Florida and, if the former are present in our State, they lie at great depth with no influence on or connection with the artesian reservoir. Furthermore, the water from these deeply buried formations is known to be highly charged with mineral solids and too salty for public and domestic use.

Geology of Florida
History records that Ponce de Leon was in search of the "Fountain of Youth." Without doubt some early explorers had related fantastic and ' fascinating stories about the large springs of this newly discovered world which so intrigued Ponce de Leon that he felt compelled to search for this land of "Eternal Youth." So it may be inferred that hydrology played a leading role in focusing world attention to this portion of the United States.
Be that as it may, Florida does have an interesting geological history. All of the formations present at the surface, and to a considerable depth, are of sedimentary origin and geologically speaking are recent or young. Underlying these formations, however, we know there are still older sediments that rest on older rocks, some of which are metamorphic and some igneous in character. This rock sequence indicates that Florida has been here since quite ancient time.
To better understand the occurrence, movement and development of ground water one must turn to geology as the source of help. There is a very close relationship between the occurrence of ground water, the configuration of the ground surface, and the character and







FLORiIDA STATE HIORTICULTURIAL SOCIETY, 1950


extreme western portion of the State, 0 $
and here the lack of subsurface data may account for its apparent absence or its
having not been recognized.
Lying immediately above the Ocalalimestone is a group of Oligocene lime-@ stones to which appropriate names have a
been given, and all have physical charac-0 teristics quite similar to the Ocala lime- .'
"d C
stone, except the Marianna, which is a)
finer grained but resembles in many respects the Ocala limestone in that it is 41 0
soft, cream-colored and generously fossiliferous. The Byram marl is of local occurrence and does not play a prominent A
part in relation to water supplies, but ~M e 0
the Suwannee and Flint River limestones 0 ~~2
are good aquifers. These limestones are rather hard, white to cream-yellow, and quite pure, the calcium carbonate content being comparable to that of the H ~ ~ 0 c
Ocala limestone. It is the Suwannee E
limestone that yields the generous supply of water developed by the City of St. Petersburg and is currently being considered as a source for the entire Pinellas0 Peninsula.
Of the Miocene formations, the Tampa
limestone and Hawthorn formation are a
of most importance, because of their wideW distribution and general characteristics. The Tampa limestone is yellowish in Z
z
color, fairly hard, and less pure than the.2 Suwannee and Ocala limestones. It often 4
contains as much as 25 percent silica, some alumina and ordinarily very little 0
magnesium. This limestone upon weathering, therefore, leaves quite a residue of insoluble materials. It is, however, . .
-in important acquifer.EThe Hawthorn formation varies from 4
a rather pure to a phosphatic limestone with large percentages of sand, marl and clay. In some parts of the State it a) )
is largely made up of thick beds of clay 0 Z)
and sandy clay. Under such conditions 4 .2 0
it acts as an impervious bed, confining C.
the water in the underlying limestones 04 P-4 p.
under artesian pressure. It contains










I __ - II


Aahua formation


Sand, clay, and phosphate.


Bone Valley formation 50 Sand, clay, and phosphate.
Buckingham marl 45 Calcareous clay.,
Sand, shell, and marl. Yields water to Caloosahatchee formation 50 shallow wells. Some of the water is highly
mineralized.
Charlton formation 60 Calcareous clay and impure limestone.
Citronelle formation 250 Sand, gravel, and clay. Yields water to
shallow wells.


Tamiami formation


Sandy limestone to nearly pure quartz sand. Important source of water to shallow wells.


Sandy shell marl containing clay. Yields
Duplin marl 50 water to shallow wells and in part artesian.
Shoal River formation 170 Fine micaceous sand and sandy clay.
0 tC . :Sandy limestone and sand with shell.
r_ Chipola formation 56 Yields water to shallow wells, in part ar__ __ _ __ _ tesian.
41 Interbedded sand, clay, marl, and limestone, with lenses of fuller's earth. ImSHawthorn formation 500 portant source of water, in part artesian.
Locally the water is highly mineralized.


Tampa limestone


Limestone and sandy limestone, in places dolomitic. Important source of water, much of which is under artesian pressure. In local areas near coast water is highly mineralized.


Pliocene


Miocene







Ii-lard, resonant limestone to soft, granular & Suwannee limestone 100 limestone, containing some silica. ImportEi ant source of artesian water.

0012 Flint River formation Sandy and pebbly limestone and calcareous
Olgcn (Northwest Florida) 100 dirty sand. Locally silicified.
Byram limestone 40 ~ Limestone, sandy limestone and some
clayey beds. Limited areal extent.
Chalky limestone. Locally an important Marianna limestone 30 source of water in Jackson, Holmes and
(Northwest Florida) Washington counties.
Predominantly porous limestone. Important source of water, most of which is under Ocala limestone 360 artesian pressure. In local areas the water
is highly mineralized.
Chalky limestone containing some gypsum Avon Park limestone 650 and chert.

Crystalline limestone, argillaceous limeEocene Tallahassee limestone 650 stone.

Chalky limestone locally containing gypLake City limestone 500 sum and chert.

Oldsmar limestone 1,200 Predominantly limestone but contains some
0 gypsum and chert. '90 Salt Mountain limestone 200 Soft, chalky limestone.
S (Northwest Florida) ______0 Cedar Keys limestone 570 Hard limestone.

Cd Porters Creek formation Seearitgayoblcca.
0 ;
" (Northwest Florida) hundred


*Water in these beds combine with the water in the Ocala limestone. Prepared by: Florida Geological Survey, P. 0. Drawer 631, Tallahassee, Florida.


After UOOKe.







GUNTER: GROUND WATER RESOURCES


varying quantities of water and in some sections is important. It is the phosphatic limestone portion of the Hawthorn formation that yields water in some areas so high in fluoride content that it is detrimental to tooth enamel in children.
The several formations grouped collectively under Pleistocene and Pliocene are all water-bearing, and water from these surface or near-surface formations is being developed extensively at present, especially in the southern portion of the Florida Peninsula where the deeper lying artesian water is generally quite salty. These formations consist of limestone, shell marl, coquina and sand. Ordinarily the quality of the water in these upper formations is better than that in the deeper artesian aquifers, but the quantity is far less. One exception, however, is the Tamiami formation of southern Florida from which Miami and other cities of Dade County get copious water supplies. According to the United States Geological Survey, the Tamiami formation is "one of the most productive aquifers in the world."
In western Florida one of the best water supplies in the State is obtained from sand. At Pensacola, for instance, wells are about 250 feet deep and the water is almost as soft as rain water, with a mineral solids content of only 41 parts per million. In some parts of Florida the water from these shallow formations is high in iron, causing objectional staining.
Piezometric Surface in Florida
Since its establishment in 1907, the Florida Geological Survey has cooperated with the United States Geological Survey in geologic and ground-water studies. During the past twenty years these studies have centered almost entirely on ground water. This research has given us much practical in-


formation about the geology, the character and capacities of the several formations, also the direction of flow and rate of movement of ground water. These studies have enabled us to construct a map showing the height above sea level to which water will rise in wells that penetrate the artesian formations. To construct such a map it is necessary to measure the depth to water
-or to obtain pressure head in areas of artesian flow-in wells throughout the State, and to know the elevation of each observation well. With this information it is possible to plot the wells on a map and to show by contour lines the surface to which water will rise from a given formation, or group of formations acting as a hydrologic unit. This is called the piezovietric surface. See Plate I.
This map is most practical. With it the well driller can, with a large degree of accuracy, estimate the level at which water will stand above sea at any locality along a given contour, and from this determine the best type of pump installation for the most satisfactory job. The map also shows the areas of "piezometric highs," as for instance, the one in Polk County which is the principal source for artesian water in central and southern peninsular Florida. These piezometric high areas are also termed recharge areas, while those where such surface is low are called discharge areas. Furthermore, the map readily indicates the general direction of artesian water movement, which is more or less perpendicular to the contours, moving from high to low contours. And finally the map outlines the areas where the piezometric surface rises above the land surface or the area of artesian flow. Unfortunately, within this area the artesian water is very highly charged with mineral solids, in some instances too high for use.








FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Factors Affecting Florida's Water
Supplies
The source of the abundant water supply in Florida is rain. Variations in rainfall bring about periodic droughts and floods. During droughts we become alarmed about the adequacy of the water supplies, during floods we too eagerly dispose of excesses as rapidly as possible. This excessive, rapid disposal by drainage, without due consideration of needed storage basins or reservoirs to hold the excess for release in time of low supply, has undoubtedly contributed to some of the problems now confronting the State.
Glancing over the rainfall record of the United States Weather Bureau, 1937-50, or the last 13 years, it is seen that the average annual rainfall for Florida was 55.37 inches, the lowest was 43.17 inches in 1938, and the highest was 72.37 inches in 1947. In 1949 there were only 50.13 inches and in the first half of 1950 (January-June), only 15.41 inches were recorded. Evidently, the deficiency beginning in 1949 is continuing in 1950 with even greater severity. Although Florida does have a high average rainfall, the State does suffer droughts sufficiently severe to cause extensive crop damage, largely because of the highly seasonal character of rainfall. Low relief and very porous soil conditions are conducive to high absorption and low run-off. Evaporation is excessive in Florida and this together with transpiration accounts for an enormous volume of water loss.
When surface water levels are high there arises a clamor for drainage and water so disposed of is lost and not available as a backlog in the dry period which is sure to follow. During the boom of the 1920's Florida literally went through a drainage spree. There just was not enough naturally dry land for all the projected subdi-visions, so drainage was resorted to with abandon,


the ultimate effect on the welfare of the State was never considered. To overcome the harmful effects of over-drainage, consideration should be given to the construction of baffles, or retaining structures, to control the run-off and permit the impounding of as much of the water as safely possible. This could later be released and used.
The 1950 United States Census records an increase of 44 percent in Florida's population during the decade 194050, while the national gain was 11 percent. Florida indeed is growing rapidly in population, in winter tourist popuIation and in new and expanding industries. With this development has come such increased demands upon our water supplies as to cause grave concern in some areas. As example, salt water encroachment in the Pinellas Peninsula has been caused by overdevelopment for municipal use and irrigation purposes; as a consequence that region now draws large quantities of water from the Odessa-Cosme area in Hillsborough and Pasco counties, and plans are now under consideration for further expansion. Salt water encroachment problems have also confronted Fort Myers, Tampa, Panama City, and Pensacola on the west coast, and Fort Pierce, Daytona Beach, and a strip along the east coast from St. Augustine southward. As a result, attention is being given to development of water supplies from the more shallow formations, but the search for such shallow supplies has not always been successful. However, the salt content of the artesian supply has not entirely prevented its use for irrigation, for many artesian wells are used for this purpose even though the water may be too saline for domestic, municipal or industrial purposes.
Large industrieshave in recent years moved into Florida, especially the pulp mills, and these mills use tremendous volumes of water. Problems have de-







GUNTER: GROUND WATER RESOURCES


ized that the ground-water reservoirs are naturally discharging many hundreds of millions of gallons of water a day, much of which can be salvaged and used whenever it is needed. The tremendous discharges of Florida's large limestone springs, which rank among the largest in the world, forcibly demonstrate the large capacity of the ground-water reservoirs. The average flow of Silver Springs alone is equal to the estimated total consumption of ground water in the
State."
And too, large quantities of water yet untapped through central, northern and western Florida are available for the industrial future. The problems, however, that have developed in certain more or less limited, or local portions of Florida must certainly be taken as warnings that there is a limit to the yield of potable water, and learn from such warnings to develop and conserve supplies. To do this there must be continuous study of the occurrence of water, the character of water-bearing formations, the depth from which supplies can be most successfully obtained, the possible capacities of such formations, and other related factors. Studies of this character are in progress by the Florida Geological Survey in cooperation with the United States Geological Survey. General State-wide studies and more detailed studies in particular areas or counties are in progress.
In summary it can be said that Florida is fortunate in its water resources. Its rainfall is one of the highest, and its formations have maximum absorption capacity. With'all the assistance Nature has so generously bestowed upon Florida with respect to our natural resources including water supplies, we must learn to utilize them wisely and provide specific controls through which conservation would become a reality.


eloped in those areas, but so far have been met quite satisfactorily. Mineral industries also use quantities of water in processing their products. Air conditioning is another factor causing large drafts. Last but not least, more and more water is used for irrigation.
In February, 1950, the United States Geological Survey tabulated an estimate of the consumption of ground water in Florida as follows:
Gals. per day
Public supplies serving
100 or more people . 160,000,000
Industrial supplies . 200,000,000 Agricultural supplies . 100,000,000 Domestic supplies ------------ 40,000,000

Total . 500,000,000
This figure of 500,000,000 gallons of water per day is impressive and should cause everyone to think clearly and plan wisely when expansion is contemplated. This is particularly true in those areas where over-draft can cause the infiltration of salt water. Pollution in some regions, too, has caused grave concern. Such pollution is the direct consequence of natural drainage, drainage wells, the disposal of storm waters, sewage and industrial waste directly into formations from which potable ground waters are obtained.
However serious ground water problems may be in some areas, there is still room for optimism on the whole. In this the following, quoted from Information Circular No. 3, Florida Geological Survey, "Ground Water in Florida" by H. H. Cooper, Jr., and V. T. Stringfield of the United States Geological Survey, is most pertinent:
"The consumption of 500 million
gallons of water a day is, of course.
a heavy draft on the ground-water resources, but this draft should not be a cause for concern in regard to the State as a whole when it is real-







FLORIDA STATE HORTICULTURAL SOCIETY, 1950

PORTABLE IRRIGATION ON THE RIDGE


MORTON HOWELL
Waverly
Does Irrigation Pay? This question has been asked many times by Growers located in the Ridge Citrus Producing area of Florida. If it does not pay, there has been millions of dollars very foolishly spent in the Ridge area, especially in the past two years. There are two methods of irrigation used in this area I am discussing. First, is with permanent installation of pumps with power units, using underground mains or conductor lines and either overhead sprinklers or portable sprinkler or flooding lines. This type requires greater initial investment with less operational expenditures. The second type is with portable pumps and power units and portable conductor and distribution pipe. With a source of water available, this type of unit can be moved from property to property, thereby on an acreage basis reducing the initial investment but, increasing the operational expense. This method is used by many in the Ridge Section which has many lakes.
Do you know that many Growers who were dependent on Portable Irrigation during the past spring and summer, have more money invested in the present crop for irrigation than all the other production costs combined? Yes, when a property is far removed from a source of water, portable irrigation certainly does deplete the bank roll fast. This is true even if you own the equipment and not just when you hire it done. In addition, it is a job which has no end until it rains. When will it rain is the sixty-four dollar question.
In my opinion there are two types of irrigation. One is "Preventive" which implies not allowing the tree to develop a tight wilted leaf condition or soft


fruit and the other is "Curative." This type is used in salvaging a crop or preventing mortality of the trees.
It is bad, but true that many Growers never plan on irrigation until it gets dry. Then those without irrigation get panicky and will pay virtually any price to obtain water. Unfortunately, in many cases this type of irrigation presents the greatest gamble.
My initiation to portable irrigation was with a worn out Buick motor and a low head centrifugal pump. The suction was a 22-foot length of 6-inch well casing. There were 400 feet of 6-inch 28 gauge galvanized slip joint pipe for conductor line and 2,000 feet of 4-inch, 28 gauge slip joint pipe for conductor and distribution line., The distribution was by the flood system. I had many experiences in attempting to keep water on the tops of some of those hills or preventing washing on the hillsides. Of course, keeping pipe together going up some of the steep grades sometimes produced a problem. The principle requirement then to operate that type of unit was the "Patience of Job." If we had the maximum of luck, we put water on part of ten acres in f our twelve to fourteen hour days. As usual, during most dry periods we were working around the clock.
During the late thirties after two successive dry Springs with very little irrigation and much hauling of water in barrels to groves, some decent portable irrigation equipment began creeping into the picture. The pumps and power units were some better but the big improvement was in portable pipe This was known as "Lock Joint Type.' It was fourteen gauge zinc coated steel with enlarged or bell type female end. Inside the female end was a rubber gasket. This gasket grew tighter as







HOWELL: PORTABLE IRRIGATION


water flowed from the pump. Protruding f rom the f emale end were two or four receptacles so arranged that when the lugs, located on the male end, fitted into these recesses and the pipe was slightly turned, it locked. In addition to being virtually leak proof, under pressure, and slightly flexible, in the event of a power unit stopping and the foot valve on the pump suction not seating there would not be a vacuum created and causing the pipe to flatten. This was the case with slip joint pipe. The main trouble with that zinc coated steel pipe which was in sixteen foot lengths, was its weight. One man could carry it but with great difficulty. During the war years with a scarcity of labor, this presented an acute problem.
The labor problem and the increased use of aluminum after World War Il was the next important step in Portable Irrigation. The production of portable aluminum pipe began to appear in this territory. This was a definite improvement. Not only a labor saver, which was greatly needed, but due to less pipe friction more water was pumped with less power through the same size pipe. With this type pipe, using 4-inch sprinklers one Grower's daughter in our organization handles the moving of the sprinkler lines by herself.
Along with aluminum pipe there developed more careful selection, by the buyer and seller, of the pump and power unit required for that particular job.
In the past a Grower bought a pump and obtained a power unit of some description and hooked them up. The power unit might gain maximum efficiency at 2,400 RPM and the pump at 1,600 RPM but it didn't make a great deal of difference. The main object was to have at least some water flowing at the end of the pipe.
At the present, one sees high head pumps, which pump a great deal of water with high pressure against much


pipe friction and terrain elevation. Power units pull these pumps direct connected or belt driven. Most of them have a clutch which allows easier starting of the power unit and priming of the centrifugal pumps.
There are some Growers with properties not located near lakes which do the following: Drill a well and mount a turbine pump on the well with a gearhead and power take off shaft extended. They put the same size pump on the various wells. Then they use one power unit and their portable pipe on all three or four properties.
In selecting equipment for use in portable irrigation much thought should be given to the subject. Such as height of property above level of water, size acreage, and distance from source of water. I am assuming, that you would want the most economical unit to operate. Beginning with a smaller unit to be used on plots located on a lake consisting of ten acres or less. In this situation, a small power unit with small high head pump that will supply a minimum of 300 GPM with a maximum head involved, is sufficient. I would suggest 6-inch aluminum conductor lines and 4-inch aluminum sprinkler lines. This unit, after assembling, can easily be operated by one man. This type of grove would usually have a rather steep slope and therefore, you would not want very much water flowing. With less water, the soil will absorb it without washing. Your sprinkler lines would be approximately 330 feet in length. One 330 foot line would be operating while the other was being moved.
The next size unit would be a high head pump that would deliver 700-750 GPM with comparable power unit that would deliver the maximum of water required with a maximum of head to operate against. The optimum conductor line would be 8-inch aluminum or with less head, 6-inch would suffice. The







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


sprinkler lines would be 5-inch aluminum of 660 feet in length per operating line. Where there is a maximum head to be operated against or where it is advantageous to use 990-foot sprinkler lines, I would suggest 1000 or 1100 GPM pump with power unit. The Big Bertha -of 'Portable Irrigation is the 1,500 t6 1,600 GPM high head pump and power unit to match. This would use 84hch aluminum conductor pipe with 6-inch sprinkler lines either two 660foot operating lines or one 1,320-foot operating line. This unit is used to a good advantage where a number of 10 or 20-acre tracts can be irrigated from one source of water. In addition it can furnish water to properties up to one and one-half miles distance from a source of water and against extreme heads. Actually you are operating two conventional 660-foot lines with just one pump and power unit. The time factor is increased by inserting crosses with valves'into the conductor lines. With the use of one additional sprinkler line to change from' one property to another the purn , p never ceases operation. For example, when crosses with valves are -inserted in the conductor line while it is being assembled eighteen or twenty .different blocks spread over a long distance, can be irrigated without ever stopping the pump. Of course, it isn't economical to use on small individual acreages due to cost of moving and setting up.
There are two factors of great importance in Portable Irrigation. They are the method employed in moving and time f actor between moves. They work Very closely together. It is always like working a jigsaw puzzle and shortage of'pipe is usually the "fly in the ointment." Avoid successive moves where all the'p - ipe you have is required. It is indeed difficult to always have enough 'Pipe foray type of portable irrigation.
-.Due to pipe scarcity during extended


periods of drouth a bit of trading by various organizations has proven beneficial to all involved. In other words when one organization is set up near a property of another, the organization, so set up does the irrigation for another or at least rents the pipe for that property to be irrigated prior to its being moved.
In the method of moving, is the al I important question of what type of equipment to use in hauling the pipe. This depends on distance between moves and many times what is available to use. Almost every conceivable type of equipment is used on the Ridge. Everything from mules and sleds to semi-trailers. One organization comes up with a useful piece of moving equipment and it is quickly copied by others.
The time factor mentioned above is all important. This means primarily do not over extend yourself. During extended periods of drouth properties have to be irrigated even six or seven consecutive times. Therefore, to protect your interest or the Growers' interest, you must be able to repeat the operation prior to the property being depleted of moisture. If you do not, the previous irrigation or irrigations have gone for naught and much is lost.
Make a survey of your needs, have a reputable organization advise you as to your requirements, usually add 2517 average on these requirements and you will be in position to have an economical operation.
There are indications that the Portable Irrigation in the Ridge area is being improved every year. This improvement is being made by semi-permanent installations. This is where growers are putting in an underground permanent conductor line by a cooperative plan. Portable pumps and sprinkler pipe is used. This is an excellent opera-







SMITH AND REUTHER: RESPONSE TO BORON


necessary. More efficient facilities will have to be developed in reducing application costs. More research work is necessary in order that water is not wasted. This operation of Portable Irrigation will definitely develop fast if the next ten years are as generally dry as in the past ten. In closing, I urge you to start thinking and doing something about this all important problem of Portable Irrigation.


tonal saving and reduces the time factor, as it is moving of conductor line which is the bottleneck.
I think we are yet in the dark ages on Portable Irrigation. Much has been done in its development during the past two or three years. Yet more has to be done in lowering the cost per acre inch of water applied to the citrus groves. More Growers are thinking in terms of Water Conservation which is vitally


each treatment. Water was applied between nutrient feedings in amounts that induced leaching Further details of the method of culture are presented in a previous article (6).
Leaf samples were collected each year and analyzed for various major and minor elements. Trunk diameter measurements were made semi-annually. Fruit was allowed to develop during the third year and Was analyzed for total soluble solids, ascorbic acid, and citric acid.

Results and Discussion
In general, excellent growth was made by all trees. The size attained was equal to or greater than identical trees growing in soil adjacent to the plots. All growth was nearly normal in appearance except that the low-boron trees showed mild deficiency symptoms in the foliage (4) during the fall months of the second year, and the high-boron trees showed mild toxicity symptoms of occasional tip burn and yellow spots
(1) throughout the test period. These symptoms were more pronounced during 1948, when the mean total boron content in dry leaf samples was 386 p.p.m., than in 1949 and 1950 when it was about 265.


PAUL F. SMITH AND WALTER REUTHER U. S. Subtropical Fritit Field Station
Orlando

Previous reports on the boron nutrition of citrus have been. concerned c iefly with deficiency and toxicity responses. The objective of the present study was to maintain trees at different levels of boron between these two extremes and to observe any differences t a oc u r in regard to general growth pattern, mineral composition of the leaves, and fruiting behavior.
Twelve young Valencia orange trees which were budded on Routh lemon s ock, were planted into 50-gallon containers filled with white quartz sand.
Beginning May 28, 1947, complete nutrient solution was applied twice w e y a e ate of 2 to 3 liters per
a location. The rate of boron used in the nutrient feeding was the only diffErential. variable for the succeeding three years. The lowest boron level was that which was supplied as impurities in the C.P. salts and the lake w iter used as a water source. A medium boron level of 0.5 p.p.m. and a high of 2.) p.p.m. were maintained as the other two treatments. Four trees received


THE RESPONSE OF YOUNG VALENCIA ORANGE
TREES TO DIFFERENTIAL BORON SUPPLY IN SAND CULTURE







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


The high boron trees showed some tendency toward forming a less compact top than the others. They had fewer, but larger, branches and a more open character. The mean tree size was nearly identical in all three treatments. This is indicated by the cross-sectional trunk area measurements in table 1.
The leaf samples collected on the first three and last sampling dates shown in table 1 were mature springflush leaves. A broad range in the B concentration within the leaf was induced and maintained. This range was over 24-f old- in the summer of 1948 and over 10-fold in the summers of 1949 and 1950. The differences in the other elements in these mature samples are relatively small. Phosphorus tends to be present in slightly greater concentrations when B is low. Such a relationship -has previously been found with sunflowers (2).
Three samplings were made from young leaves, which were developing in the fall at the time that a crop of fruit was maturing. Under these conditions the difference in the P concentration was greater than with mature leaves, although the difference appeared to diminish as the leaf approached maturity. The concentrations of the three base elements, K, Ca, and Mg were also influenced in these younger. leaves. When B was supplied in a very limited amount Mg had a tendency to enter the leaf in greater amounts, and reciprocally, K in lesser amounts. Calcium appears to have been depressed at the highest boron level. Here again it appears that these differences are perhaps temporary and tend to diminish as the leaf grows older.
Nitrogen, manganese, copper, iron, and zinc do not appear to have been influenced in any way by the variation in boron supply. Sodium was determined on the same collections for which iron values a re shown and showed no differ-


ences which were attributable to the rate of boron supply. .
From 10 to 15 pounds of oranges were produced by each tree during 1949. These were picked and analyzed on February 6, 1950. No systematic differences were found in the yield, fruit size, rind thickness, juice content, or percentage of total soluble solids and citric acid in the juice. The only difference that was consistent in all four replications was a reduction in the ascorbic acid content of the juice in the low-boron trees. This treatment averaged 49.8 mg. per 100 ml., as against 57.0 and 54.9 for the medium and high boron treatments, respectively. This response may be indirectly attributable to the boron suply, however, and more closely associated with the higher level of phosphorus in the low-boron trees. This latter relationship was found to exist under orchard conditions when the leaf phosphorus was increased without changing the boron status of the trees
(5).
The literature on boron nutrition shows several cases with various plants of a lack of growth response to a diff erential supply of this element between the limits of deficiency and toxicity levels. On the basis of this limited study with Valencia oranges, citrus seems to be no exception to that rule. Apparently normal trees can be grown with very limited applications of -boron if it is supplied at frequent intervals. Likewise, applications of boron in amounts which produce mild toxicity symptoms do not seem to interfere appreciably with the functioning of the plant. The evidence presented is the first to show the relatively small effect of rather large variations in the boron content .(maximum range 16 to 386 p.p.m.)- of citrus on growth, fruiting, and the concentration of other mineral elements in the leaves.- A similar range (30 to 305 p.p.m. boron) in mature Va-







TABLE 1
THE RELATION OF BORON LEVEL TO CROSS-SECTIONAL AREA OF THE TRUNK, AND DRY WEIGHT AND MINERAL COMPOSITION OF LEAVES OF YOUNG VALENCIA ORANGE TREES AT DIFFERENT INTERVALS OF A THREE-YEAR. CULTURE PERIOD. TREES PLANTED APRIL 28, 1947


Boron Mean trunk Mean leaf applied X-section weight (p.p.m.) (cm. 2) (Mg.)


Percentage of leaf dry matter


P.p.m. in leaf dry matter


N P K Ca Mg B Mn Cu Zn Fe


0.00 3.08 193 2.82 0.50 3.07 176 2.78 2.00 2.73 193 2.71

0.00 4.89 274 2.91 0.50 4.75 272 2.89 2.00 4.49 330 2.81

0.01 14.56 364 2.26 0.50 14.77 358 2.25 2.00 13.89 389 2.15


9-4-47
5 months


7-10-48
6 months


8-5-49
6 months


8-30-49
1 month


9-29-49
2 months


12-5-49
4 months


6-8-50
5 months


414 2.15 365 2.23 379 2.12

458 2.44 419 2.38 431 2.34


0.01 18.13 506 2.30 0.50 18.18 454 2.35 2.00 18.36 477 2.31 0.01 20.52 304 2.35 0.50 20.67 314 2.20 2.00 20.87 326 2.27


0.150 1.84 2.95 0.395 41 42 0.171 1.77 2.98 0.360 90 47 0.136 1.79 2.98 0.352 117 41

0.164 2.86 2.42 0.194 16 33 0.156 2.84 2.55 0.194 i44 44 0.161 2.92 2.52 0.202 386 46

0.133* 1.84 2.68 0.288 25 31 0.121 1.72 2.84 0.242* 93 34 0.112 1.99 2.70 0.267 263 30

0.178** 1.84** 2.61 0.512** 17 24 0.147 2.13 2.69 0.442 58 35 0.146 2.15 2.20** 0.444 130 25

0.175** 1.82** 2.90 0.524** 20 28 0.140 2.04 2.74 0.435 67 32 0.137 2.25 2.50** 0.421 158 29

0.157* 1.65 2.98 0.450* 24 44 0.133 1.68 2.98 0.400 78 45 0.138 2.03** 2.55** 0.398 168 36 0.119 1.48** 2.46 0.349 25 43 0.117 1.80 2.54 0.312 104 38 0.114 1.78 2.41 0.351 262 40


8
9
8 - - cj

8 - 74
9 - 80
8 - 64 >

14 47 83
14 41 83
13 43 76

14 29 66
14 24 68
14 25 65

13 29
15 36
14 36
C
13 29
14 28
0
13 33
12 34
12 33
11 32 -


L.S.D. between any two means @ 0.05
(& 0.01


N.S. N.S. N.S. 0.020 0.22 0.27 0.040 2.7
- - 0.027 0.30 0.36 0.053 3.6


N.S. N.S. N.S. N.S.


6Significant difference.
**Highly significant difference.


Sampling date and leaf age


0.01 0.50 2.00

0.01 0.50 2.00






FLORIDA STATE HORTICULTURAL SOCIETY, 1950


lencia orange leaves was found in a recent survey (3) of 75 commercial orchards in the major citrus producing areas of the United States.
Summary
Young Valencia orange trees were grown for three years in large outdoor sand cultures on complete nutrient solutions that varied differentially only in the amount of boron. Three rates of boron were applied to single-tree plots. The plots were replicated four times.
No difference in tree size resulted from the differential treatments.
Rather large differences in the boron content of the leaves were induced. The low-boron plants showed mild foliage deficiency symptoms during the second year but not in the first or third years of growth. The high-boron plants showed slight leaf symptoms of toxicity throughout the three-year period.
Mature leaves showed virtually no differences in mineral composition other than the 10- to 24-fold difference in boron. Phosphorus tended to be present in slightly greater concentration when boron was low.
Young leaves showed this same relationship with phosphorus in a more pro-


nounced manner. When the boron supply was low, potassium accumulation in the leaf was retarded and magnesium accumulation accentuated. The rate of calcium accumulation was depressed at the highest boron level. These differences appear to diminish as the leaf approaches maturity.
The only consistent difference in the quality of the fruit produced during the third year was a slight reduction in the ascorbic acid content in the low-boron cultures.
LITERATURE CITED
1. CAMP, A. F., and FUDGE, B. R. Some symptoms of citrus malnutrition in Florida. Fla.
Agr. Exp. Sta. Bull. 335. 1939.
2. REED, H. S. A Physiological study of boron deficiency in plants. Hilgardia 17: 377-411.
1947.
S. REUTHER, W., SMITH, P. F., and SpEcHT, A. W.
A comparison of the mineral composition of Valencia orange leaves from the major producing areas of the United States. Proe. Fla. State
Hart. Soc. 62: 38-45. 1949.
4. SMITH, P. F. and REUTHER, W. Observations on boron deficiency in citrus. Proc. Fla. State
Hart. Soc. 62 : 3 1-37. 1949.
5. SMITH, P. F., REUTHER, W., and GARDNER, F. E.
Phosphate fertilizer trials with oranges in Florida.
11. Effect on some fruit qualities. Proc. Arner.
Soc. Hort. Sci. 53: 85-90. 1949.
6. SMITH, P. F., and REUTHER, W. The response of young Valencia orange trees to differential boron supply in sand culture. Plant Physiol. 26:
(In Press). 1951.


J. F. L. CHILDS
Bureau of Plant Industry, Soils, and Agricultural Engineering, United States Department of Agriculture
Orlando
In 1945 G. H. Godfrey published an article entitled "A Gummosis Associated with Wood Necrosis" (4), in which he reported what was presumed to be a new disease attacking citrus trees, principally grapefruit, in the Rio Grande Valley of Texas. This disease is con-


sidered by the Valley growers to be their most serious citrus disease.
In November of 1949, in company with Dr. Godfrey and his former assistant Mr. Carl Waibel, I saw the Rio Grande Gummosis disease on the Experiment Station grounds at Weslaco. Several days later symptoms of the same disease were seen on grapefruit trees in the Coachella Valley area of California. Subsequently Mr. Waibel informed the writer that he had assisted Dr. Fawcett in identifying the disease


RIO GRANDE GUMMOSIS Its Occurrence in Florida Citrus







CHILDS: RIO GRANDE GUMMOSIS


in California and that Dr. Fawcett was satisfied that Rio Grande Gummosis is distinct from the virus disease, psorosis. This has an interesting bearing on the early history of gummosis in Florida.
Upon returning to Florida, many gummosis lesions were examined by the writer and were found to resemble closely the trouble seen in Texas and California. Later Mr. Waibel visited Florida and confirmed the suspicion that Rio Grande Gummosis is none other than the old Florida Gummosis disease under a new name. Without going into the complete history of this disease, it should be noted that the earliest detailed description of gummosis in Florida was published by Fawcett in the Agricultural Experiment Station Report of June 1907 (1). Later he published other reports of his work on gummosis, in one of which (2) he explained how to distinguish gummosis from foot-rot (Phytophthora citrophthora), and from leprosis (Florida scaly bark disease). Recognition of the importance of gummosis disease in Florida reached its high point when Rhoads and DeBusk published their bulletin in 1931 (5). After that date little was published, and gummosis eventually came to be regarded as merely a name to describe any disturbance giving rise to a little gum.
This situation is the result of a peculiar set of circumstances and events. In the first place some of the symptoms of gummosis are remarkably like certain symptoms of foot-rot on the one hand and like certain symptoms of psorosis on the other. As a result gummosis has been confused with these diseases. In addition gummosis has been known under other names such as "tears," and "gum disease," which led to confusion. Uncertainty as the identity of the causal organism has been detrimental to understanding gummosis. When Fawcett reported (3) that he had


isolated Diplodia natalensis from gummosis lesions and that Diplodia caused more profuse gumming than any other isolate many were led to infer that Diplodia was the cause of the gumming when neither foot-rot nor, psorosis seemed to fit the case. Although Fawcett reported that Diplodia inoculations did not form typical gummosis lesions
(3), that fact was overlooked by many. It seems as though it was overlooked by Fawcett himself for when he later recognized the disease in California he did so under the name of Rio Grande Gummosis. However Diplodia infections cause the wood to become dark grey to black in color, which contrasts sharply with the buff and orange color typical of citrus wood infected with gummosis. Also, Diplodia readily attacks sour orange causing profuse gumming, but Stevens (6), Rhoads (5), and Godfrey (4) all agree that sour orange is highly resistant to if not immune from gummosis disease. As a result of these facts there is basis for considerable doubt that Diplodia is more than a secondary invader of gummosis lesions.

SYMPTOMS OF GUMMOSIS IN
TEXAS AND FLORIDA
The symptoms of the gummosis disease as seen in Texas parallel closely the symptoms in Florida and are in close agreement with those described by Fawcett in 1907. On that basis, the disease as found in Florida, Texas, and California can safely be regarded as a single disease for which the name gummosis, as originally used in Florida, should take precedence.
Gummosis lesions may be active at any time of the year and on lemon trees they appear to be active almost continuously. - On grapefruit the period of greatest activity seems to be early ,spring. This year (1949-1950).the disease was especially active from Decem-







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


ber through February, perhaps because of an unusually warm winter and an early spring. Since lemons ceased to be grown commercially in Florida (due in large part to gummosis, although foot-rot is usually blamed), gummosis is most frequently seen affecting mature grapefruit trees. Any point on the trunk and larger limbs may be attacked. The following table (Table 1) adapted from Rhoads and DeBusk (5) indicates the relative susceptibility of several citrus species to gummosis.
TABLE 1.
Tise Susceptibility of Several Species of Citrus to Gummosis as Indicated by tbe Presence and Extent of Lesions. Adapted from Rhoads and DeBusk (loc.cit.).
SPECIES OF CITRUS SUSCEPTIBILITY RATING Lemon Most susceptible
Grapefruit Very susceptible
Sweet Orange Moderately susceptible
Tangerine Very resistant
Sour Orange Most resistant

There are roughly speaking two types of lesions, depending on age and manner of infection. In appearance young infections are very similar to young infections of foot-rot, i.e., a small quantity of light-colored gum oozing from a small spot where the bark appears slightly wet or water-soaked. However, the cambial surface of the wood beneath the gumming spot lacks the brownish-yellow stain characteristic of f oot-rot infections. Frequently (at least on grapefruit trees) small woody galls or outgrowths from the wood under the bark are found associated with young gummosis infections. These outgrowths are usually green in color due to the presence of chlorophyll presumably stimulated by the disease.' So far as is known such outgrowths are not found associated with foot-rot, with Diplodia infections, or with the virus disease, psorosis. Usually there is no bark scaling at the time of first gum production, although the bark may split slightly. Young lesions appear to heal


by sloughing off a thin scale of dead outer bark, exposing a buff-colored scar. This occurs shortly after gumming ceases. The scar consists of callus tissue generated by the bark. Healing is only temporary, for later in the year, or perhaps the following year, gum exudes again, and additional scales of bark slough off, thus enlarging the lesion and repeating the cycle. In the course of repeated gumming and scaling, the lesions enlarge to cover a considerable area, and in time the wood becomes exposed. The direction of greatest enlargement is parallel to the axis of the trunk or limb and not around the circumference, as is the case with the psorosis. in addition, psorosis lesions always look ulcerated and give no appearance of healing, even temporarily. In foot-rot lesions the bark is killed down to the wood and is subsequently sloughed off as a single slab, and any healing that occurs takes place at the margins of the lesion.
In older infections of gummosis the disease usually has penetrated deep into the wood, and as a result it is often necessary to chisel through a half inch or more of healthy wood to expose the gummosis infection. When thus exposed the cut surface of the infected wood is seen to be a buff or buckskin color usually banded and bordered with a salmon-orange color that deepens in shade when exposed to the air. The banded appearance is due to the wood of certain growth rings having become impregnated with gum. Frequently gum collects in lens-shaped pockets that cause the outer layers of wood and the bark to become raised as though by large blisters. When these "gum pockets" break through to the surface large quantities of semi-liquid gum are released. The cavities vary in size, some being half an inch thick by an inch wide by two inches long, and the internal walls are usually covered with small gall-like protuberances that some-







CHILDS: 1110 GRANDE CUMMOSIS


times enlarge to the point of filling the cavity. The disease appears to penetrate long distances through the wood so that gum pockets may be formed at a considerable distance from the nearest bark lesion. The importance of the gum pockets in diagnosing gummosis disease was noted by Fawcett in 1907.
A summary of the more characteristic symptoms of gummosis is presented in Table 2, in comparison with the symptoms of foot-rot and psorosis, the two diseases with which it is most frequently confused.

Causal Organism
At present the cause of gummosis must be considered as unknown since there is no published record of typical symptoms of gummosis having been produced by inoculation with a pure culture of any organism or with a virus. The causative agents of footrot, psorosis, and Diplodia infection have been satisfactorily disposed of as possible causes of gummosis, and many years ago in Florida Fawcett (3) showed that uninfected mechanical injuries to citrus trees did not gum. It is true that certain chemicals stimulate gum formation, but the remainder of the symptom picture is lacking, i.e., cycles of gumming and healing, gum pockets, and certain other features have not been found associated with chemically induced gumming. The only other causal agent worth consideration at this


time is the one reported from Texas. Godfrey found what he describes as an actinomycete-] ike fungus associated with the disease. Up to the time I talked with him in 1949 he had been unable to obtain this organism in pure culture, but he has been able to cause the disease on numerous occasions by inoculations with chips of diseased wood. Although this organism is suspected, its causal relationship has not been proved.

Control
From the citrus grower's point of view, emphasis on the identity of the causal organism is somewhat academic. What he wants to know is how the disease spreads and how it can be stopped. Old gummosis infections in Florida and in Texas indicate that pruning wounds are the most important point of entry of gummosis, with other bark injuries only slightly less important. In Texas the disease is sometimes referred to as "wet-back" disease because it is so often associated with bark injuries caused by Mexican fruit pickers, "wvetbacks," who frequently climb the trees when picking fruit. Whether the organism can penetrate through uninjured bark is not known, though judging from some of the young lesions seen in Florida this year, it seems that it can. However, young infections that take place through the bark are easily cared for, and do not present the same hazard as infections arising in the wounds that


TABLE 2.
DIFFERENCES AND SIMILARITIES IN THE SYMPTOMS OF FOOT-ROT (PIIYTOPHIIORA CITROPHTHORA), GUMMIOSIS (CAUSE UNKNOWN), AND PSOROSIS (VIRUS).


Disease Symptoms

Gumming Bark Sloughing Gum Pockets in Wood Color of Affected Wood


Causal Organism


Foot-rot


Heavy Entire bark thickness None
Yellow to Brown


Fungus


Gummosis


Very heavy Outer scales Common Buff with Salmon Bands Unknown


Psorosis.


Practically none Outer scales None

Brown Virus







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


result from cutting off large branches. The practice has been to remove large branches by sawing them off as close to the trunk as was convenient and to let the stump heal over as best it could. Even under the most favorable circumstances, it takes several years for a large pruning wound to heal over. In the meantime, the wound is open to infection by gummosis and other diseases.
All pruning wounds three-quarters of an inch in diameter or larger should have a wound disinfectant applied to them. For this purpose few materials are as satisfactory as Avenarius or Red Arrow carbolineum. In addition, any wound 11/2 inches or larger should have a coating of water-emulsified asphalt applied to the carbolinelim dressing one week afterwards. Such treatment will maintain the wound surface in a dry, fungus-repellant state until the bark has healed over it.
Painting the surface of an old wound will not eradicate gummosis from deep in the wood. Old infections will have to be excavated with a chisel or gouge. All the discolored diseased wood should


be removed and, after several days 'of drying, the surface should be treated with carbolineum and asphalt emulsion as in the treatment of new wounds. When gummosis disease has been established a long time the grower will have to, determine whether the tree is worth the expense of treatment. Young lesions are easily excavated and heal over in a short time if proper dressings are applied. However gummosis lesions that have apparently healed over without adequate treatment are still alive and will break out with renewed activity at a later date. The proper treatment of wounds is an excellent example of the adage that an ounce of prevention is worth a pound of cure.
BIBLIOGRAPHY
1. FAWCETT, H. S. Gumming of Citrus. In Fla.
Agr. Exp. Sta. Ann. Rpt. (1907), p. xlvi-xivii. 2. - ,--- ---- Gummosis. In Fla. Agr. Exp. Sta.
Ann. Rpt. (1910), p. xlix-li.
3. - --------- Gumming. In Fla. Agr. Exp. Sta.
Ann. Rpt. (1912), p. lxxvii-xcii.
4. GODFREY, G. H. A Gummosis of Citrus Associated with Wood Necrosis. Science 102 (2640):
130, 1945.
5. RnoA~s, A. S., and DEBuSK, E. F. Diseases of Citrus in Florida. Fla. Agr. Exp. Sta. Bulletin
229 (1931), p. 66-74.
6. STEVENS, H1. E. Gummosis. Fla. Agr. Exp.
Sta. Ann. Rpt. (1914), p. lvii-lxxiv.


PRESENT STATUS OF SPREADING DECLINE


R. F. SUIT AND H. W. FORD Citrus Experiment Station
Lake Alfred

The investigation of spreading decline of citrus in Florida has been in progress for the past five years. During that time information on the varieties of citrus and the rootstocks on which the decline was found has been reported (1). In addition, the effect of the disease on the tree (1) and the rate at which the decline spreads in the grove have been discussed (1,2). At one time it was considered that the citrus nematode (Tylenciulus sernipenetrans Cobb) might be


associated with spreading decline (1) but subsequent results showed that the citrus nematode was not the causative agent for typical spreading decline (2). In the experimental work on virus transmission, no evidence was f ound to indicate that the disease was caused by a virus (1,2). Although preliminary investigations did not indicate that a fungus was responsible (1), it appears that the trouble may be the result of a fungus infection of the fibrous roots that gradually spreads through the grove from root to root (2). Numerous experiments with various types of possible control measures were conducted but no
















































Increase in number of diseased trees per tree on the margin of the declining area.
TABLE 2.
Increase in Number of Diseased Trees in Affected
Groves During a Five Year Period.
No. Diseased Trees
Grove 1945 1950 Increase
2 13 138 125
3 77 244 167
4 164 511 347
5 121 296 175
6 21 199 178
7 29 142 113
9 51 152 101
10 66 249 183


SUIT AND FORD: SPREADING DECLINE


of spread in the various groves f rom 1945 to 1950. The marginal rate of
TABLE 1.
Yearly Variation in Rate of Increase of Spreading Decline in 25 Groves.
Rate of Spread'
Grove 1945- 1946- 1947- 1948- 1949- Average
1946 1947 1948 '1949 1950
1 1.6 1.1 0.3 2.5 out 1.4 2 1.2 1.4 0.6 2.8 1.0 1.4 3 1.0 0.8 0.7 0.9 2.7 1.2 4 1.1 1.4 2.3 2.3 1.8
5 0.2 1.7 1.8 2.7 1.3 1.5 6 0.7 1.5 0.9 1.5 1.6 1.2 7 1.0 2.0 1.0 3.0 0.5 1.5 8 0.3 0.8 0.7 1.3 out 0.8 9 0.5 1.1 1.3 2.8 0.8 1.3
10 0.6 0.6 1.6 3.8 2.3 1.8 11 1.1 0.7 2.0 1.5 1.3
12 2.3 0.7 2.0 out 1.7
13 1.9 1.9 2.2 0.6 1.7
14 1.1 4.7 0.5 2.1
15 1.1 5.2 1.5 2.6
16 2.0 3.0 1.8 2.3
17 1.8 1.1 0.5 1.1
18 0.9 2.7 0.5 1.4
19 3.2 8.3 5.7
20 4.1 0.9 2.5
21 2.6 1.0 1.8
22 2.7 0.6 1.7
23 1.5 1.0 1.3
24 1.6 0.6 1.1
25 4.3 0.1 2.2
Average 0.8 1.4 1.1 2.7 1.5 1.6


successful method for the control of the disease was found (1,2).
Considering all of the information already obtained and the additional results accumulated since the last report in 1949, what is the present status regarding spreading decline?
Spreading decline occurs on all varieties of oranges, grapefruit and tangerines budded on rough lemon, sour orange, sweet orange or grapefruit rootstock. The presence or absence of the disease on other kinds of rootstocks has not been determined. The number of groves in which typical spreading decline is present are located as follows: Polk County-74, Orange County-8, Highlands County-5, and Hillsborough County-2, making a total of 89 groves. There are a number of groves in which spreading decline occurs that we do not have on our list.
Those trees which have spreading decline show sparse foliage and reduced growth but do not die. The trees within the decline area all show the same degree of decline and a distinct margin is evident with the decline trees on one side and the healthy trees on the other. The disease gradually spreads from the declining trees to the adjacent healthy trees.
Rate of Spread
To determine the rate of spread of the disease, the groves are mapped each year after the spring flush of growth. The yearly maps are then compared to obtain the number of trees that become diseased during any given year. Since the decline spreads at the margin of the diseased area, the rate of spread is obtained by dividing the number of trees that become diseased by the number of trees on the margin of the decline area. The results obtained from 25 selected groves are presented in Table 1. These data show that considerable variation occurred in the rate







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


spread varied from 0.1 to 8.3 trees with an average of 1.6 for all groves throughout the five years. Six groves showed an average rate of spread of over 2.0 for the five-year period. The greatest average yearly spread was in 1948-49 when the rate was 2.7. In general, spreading decline can be expected to move outward I or 2 trees per year.
To demonstrate the total number of trees that may become diseased over a period of years, the data obtained from 8 groves was examined. These groves had been mapped six times and complete records for the five-year period were available. As is shown in Table 2, the number of diseased trees in the groves varied from 13 to 164 when they were mapped in 1945. By 1950, the number of diseased trees varied from 138 to 511. Grove No. 4 showed the largest increase but also had the most diseased trees in 1945. However, the increase in number of diseased trees was not always greater in the groves that had more diseased trees at the beginning of the experiment as illustrated by comparison of the data from groves 5 and 6. Apparently the conditions in some of the groves were more favorable for the development of spreading decline.

Causal Agent
Spreading decline appears to be the result of a disorder of the fibrous roots of the tree. No evidence has been found to indicate that the disease is caused by a virus. Although the citrus nematode is present in a number of groves in Florida, it was not found in groves which have typical spreading decline. Two kinds of fungi can be consistently isolated from the fibrous roots of the diseased trees. One is a Fusarium sp. and the other has not yet been identified. It is probable that the spreading decline is caused by a fungus infection of the fibrous roots. A number of experiments are in progress to determine i whether


either of these two f ungi may be the causal agent.
One characteristic of a Fusarium disease is the ability of the f ungus to produce a toxic wilt-inducing material when grown in Richard's solution. This toxic material adversely affects the host, when the disease occurs under natural conditions. In the case of spreading decline, a toxic material was obtained from water extracts of the fibrous roots, the woody portion of larger roots and the leaves from diseased trees. This toxic material caused the wilting of citrus cuttings within 48 hours and of tomato cuttings in 24 hours. Extracts from healthy trees did not cause a wilting of the cuttings. Fusarium cultures No. 16, 29 and 35 obtained from diseased trees were grown in Richard's solution for two weeks and the filtrate tested for wilt inducing ability. Thefiltratefrom culture 29 was more toxic than that from the other two cultures in causing a wilt of citrus cuttings. Since.a wilt inducing material can be extracted from the diseased trees and is produced by the growth of the fungus in Richard's solution, it is indirect evidence that the spreading decline may be the result of the infection of the fibrous roots by a Fusarium.
Experiments have been conducted and are in progress to determine the effect of soil from a spreading decline area, healthy grove soil and virgin-soil on the growth of rough lemon seedlings and young Duncan grapefruit trees on rough lemon rootstock. In one series of tests, the seedlings in the decline soil show a reduction in growth compared to that of the seedlings in the othersoils. It has also been found that Tendergreen beans and sunflowers develop a greater amount of root rot when grown in soil from a spreading decline area than occurs when they are grown in, soil f rom the healthy part of the grove.' Both of the, previously. men-









trees was measured using 40 root tips from each tree. The root tips were suspended in a 2 percent glucose solution and placed in a Warburg respirometer at 33' C. where oxygen measurements were made at 10 minute intervals for a period of one hour. The rate of oxygen absorption by the roots secured from three typical groves is shown in Table 3. It was evident in every measurement that the rate of respiration of the decline trees was lower than the respiration rate of the healthy trees in the same grove. The data also indicate that in the majority of the groves tested there was a successive increase in respiration rate from the decline area up to and including the third healthy tree beyond the decline margin. In every grove the respiration rate was highest for the third or fourth healthy tree beyond the decline margin. The rate of respiration of healthy trees beyond the fourth tree was slightly lower than the third tree but usually higher than the first or second healthy tree. It was also interesting to note that the respiration rate was practically the same for all healthy trees in the same grove located more than 4 trees beyond the visible margin of spreading decline. Although these data are preliminary in nature it would appear that the decline
TABLE 3.
Respiration Rate of Fibrous Roots from Decline Trees
and from Consecutive Healthy Trees in
Advance of the Margin.
Condition -Microliters of Oxygen per Hour Tree No. of Tree Grove 1 Grove 2 Grove 3 0 Decline 15.3 23.4 22.5 1 Healthy 18.6 26.6 30.3
2 Healthy 22.5
3 Healthy 34.3 38.4 41.2
4 Healthy 33.1'
5 Healthy 31.2 31.8 .30.6
6 Healthy 29.2
7 Healthy 28.8 33.8 303
8 Healthy 28.8
9 Healthy 31.3 '29.1 29.0


SUIT AND FORD: SPREADING DECLINE


toned fungi have been isolated from the diseased bean and sunflower plants. In one instance, velvet beans were used as a cover crop in the spreading decline area of a grove. The stand was poor and about 50 percent of the plants showed root rot. A number of other kinds of plants will be tested for their susceptibility to root rot when grown in soil from a spreading decline area. If a satisfactory test plant can be found, it will be possible to evaluate the effectiveness of the various soil treatments more rapidly than can be done by growing citrus seedlings.
Control Measures
Considering the evidence obtained, it is doubtful if a treatment can be found which will rejuvenate those trees that have spreading decline. Therefore, to control spreading decline, two problems should be considered. How can we stop the spread of the decline in a grove? What soil treatment should be used before the area is replanted? In some cases, growers have attempted to control spreading decline by removing those trees which were visibly diseased. Within a few months those trees at the margin, which appeared healthy when the other trees were removed, began to show typical decline symptoms.
Before decline can be properly controlled it will be necessary to know the number of trees affected with the disorder which are located in advance of those trees showing visible symptoms. Since plant pathogens of ten affect plant metabolism a measurement of the rate of respiration of citrus leaves or roots should show whether differences exist in::_metabolic -activity between apparently healthy trees in advance of the decline margin. A difference in metabolic activity might be indicative of the spread of the pathogen.
The rate of respiration of fibrous roots. from- healthy, trees and decline









nated. Assuming that this procedure would be effective, what would be the result if this had been done in 1945 in the eight groves which we have studied? As is shown in Table 5, the number of diseased trees in every grove is greater now (1950) than the number
TABLE 4.
The Catalase Activity of Grapefruit Leaves from Consecutive Trees Across the Margin
of the Decline Area.


TABLE 5.
Hypothetical Loss of Trees by Pulling to Prevent Spread Compared to Actual Loss by Unchecked
Spread of Decline.
Trees in 1945 Trees in 1950 Grove Decline Pulled Total Decline 2 13 99 112 138
3 77 97 174 244
4 164 174 338 511
5 121 133 254 296
6 21 105 126 199
7 29 68 97 142
9 51 82 133 152
10 66 88 154 249

of decline trees plus a margin of four trees that would have been removed in 1945. Arrangements have been made to try this procedure in three groves this winter. It will be two or three years before definite conclusions as to 'its effectiveness can be obtained.
It is possible that a chemical barrier


FLORIDA STATE HORTICULTURAL SOCIETY, 1950


casual factor had an initial stimulating effect on the respiration rate of the third or fourth healthy tree. It would seem logical, therefore, that as the invasion became more severe the respiration rate was reduced as illustrated by the lower metabolic activity of the first and second healthy tree.
Respiration studies are being continued and additional indices evaluated as an aid in the interpretation of the significance of metabolism in the third and fourth healthy trees beyond the decline area.
The activity of the catalase enzyme in the leaves has been used occasionally as an indication of the rate of metabolic activity. Sixty leaf discs were selected from each tree and ground while fresh with a mechanical mortar. Catalase was determined in Heinicke tubes rotated in a constant temperature water bath. The amount of catalase was expressed as the cubic centimeters of oxygen generated in 90 seconds when the sample was mixed with hydrogen peroxide. The catalase activity of the leaves secured from one grove is shown in Table 4 although the same general relation held for other groves that were tested. In general, there were greater variations in catalase measurements of the leaves than were apparent in the respiration rate of the roots. These differences may have been due to the greater experimental error in the catalase procedure. However, it is significant that in every grove tested the third or fourth healthy tree beyond the decline margin had the most catalase present.
Since a preliminary study of the physiology of the citrus tree has indicated some variation up to the fourth visibly healthy tree ahead of the margin of the decline area, it is probable that, if all of the diseased trees plus four or five good trees around the area were removed, the disease could be elimi-


Catalase as cc. of 0,, Released in 90 See.
15.7
20.2 17.1 30.7
34.0 35.7
30.4 29.9 29.3 30.2 28.3 28.5


Condition of Tree Decline Decline Decline Healthy Healthy Healthy Healthy Healthy Healthy Healthy Healthy Healthy


Tree, No.
1
2 3
4 5 6 7 8 9 10 11
12







SUIT AND FORD: SPREADING DECLINE


maintained in a grove might stop the spread of the decline. Such a barrier would need to kill the roots to eliminate root contact and have some disinfecting action on the soil. Preliminary tests with cyanamid, formaldehyde and D-D (dichlorapropane-dichloropropene) indicated that a formaldehyde solution should be effective as a barrier. The barrier would be examined periodically and when the roots started to grow back into the treated soil, the chemical would be applied again. A system of barriers at different distances ahead of the margin has been established in nine groves. Formaldehyde at 3 gallons to 100 gallons of water was injected into the soil at the rate of 2 gallons of solution per 5 feet of barrier. It is possible that some results will be obtained by 1952.
1If either or both of the above mentioned measures of pulling marginal trees or using a chemical barrier will stop the-spread of the decline, then the problem remains as to a satisfactory treatment for the soil so that replants will grow properly. In February, 1948, two blocks of spreading decline trees were removed and the soil treated with D-D at 400 pounds per acre. The treated areas were. replanted with budded trees and records on growth are being obtained. After two years, the trees planted in the treated soil are making better growth than those in the nontreated soil. The data from one of the blocks are shown in Table 6. The D-D is not a good fungicide, but at the rate used has some fungicidal effect. In another experiment rough lemon seedlings were planted in decline and virgin soils which had been treated with D-D, formaldehyde and-ethylene dibromide-in December 1948. In October 1950, 6 out of. 18 seedlings, in the non-treated decline soil had died_ and theremaining plants had grown about two-thirds as much as the seedlings in


the treated decline soil or in the nontreated or treated virgin soil. Final records have not been made but there does not appear to be any significant difference in the growth of the seedlings whether in treated decline soil, or-in the non-treated or treated virgin soil.
TABLE 6.
EFFECT OF SOIL TREATMENT WITH D-D
ON GROWTH OF YOUNG TREES.
Treated Soil Non-Treated Soil Caliper 1.91 in. 1.75 in.
Height 5.80 ft. 4.93 ft.
Spread 5.69 f t. 5.18 ft.

To obtain additional information on various materials that might be effective as a sail treatment, a series of tests were started in May 1950. A total of 56 materials are in the test. It may be possible to obtain some information by the spring of 1951.
.Summary
Groves in which spreading decline is present in Florida are located in Polk, Orange, Highlands and Hillsboroughi counties. Over a five year period, the average rate of spread of the decline in all groves mapped was 1.6 trees per tree on the margin of the decline area. During the same period, the number of trees with the disease increased, from
2 to 9 times in different groves.
Spreading decline appears to be the result of a fungus infection of the fibrous roots. A Fusarium sp. And an unidentified fungus have been consistently isolated from the roots of diseased trees. Indirect evidence obtained by means of the "wilt test" has indicated that a Fusarium may be the casual agent.
Tests on the respiration and catalase activity of rootlets and leaves of diseased and healthy citrus trees indicated that-the disease may extend to the third or f ourth . healthy tree ahead .,of the







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


margin of the decline area. Any attempt at controlling spreading decline by removal of the trees should also include at least four healthy trees ahead of the margin.
Rough lemon seedlings have made better growth when the decline soil was treated prior to planting with D-D, formaldehyde or ethylene dibromide in


pot experiments. Field tests with D-D at 400 pounds per acre appear promising.
LITERATURE CITED
1. Surr, R. F. Spreading decline of citrus in Florida. Prov. Florida State Ilort. Soc. 60: 17-23,
1947.
2. SUIT, 11. F. and L. C. KNORR. Progress report on citrus decline. Proc. Florida State llort. Soc.
62; 45-49, 1949.


W. L. THOMPSON AND
J. T. GRIFFITHS, JR.
Citrits ExpeTiment Station
Lake Alfred
During the past two years purple mite Paratetranychus citri McG. infestations have been general throughout the whole citrus area, and they have persisted even during the summer months. As a rule, purple mites are difficult to find in August and September but during these months in 1949 and 1950, light to medium infestations were observed in many groves. Purple mite populations were at a higher level during the summer of 1950 than during any other summer period on record.
Although no particular cause has been determined for the unusually heavy and widespread infestations, favorable weather conditions for mites have existed. Purple mites are often more numerous during and following periods of dry weather and it may be significant that in 1950 the rainfall at Lake Alfred was below normal each month from January to August inclusive.
Spray and cultural practices are factors of considerable importance in the development of purple mite infestations. Thompson (2) reported in 1938 that purple mites increased following copper sprays, and in 1942 Holloway
(1) stated that the citrus red mite (pur-


ple mite) in California was more numerous following sprays containing compounds of copper, zinc and lime than where no sprays were applied. In 1944 Thompson (3) also reported that purple mites were more numerous following sprays containing lime-sulfur or compounds of copper or zinc, than where no sprays of any kind had been applied. In fact, the infestations were as heavy where lime-sulfur had been applied as a dormant spray as where either zinc or copper was used in the spray mixture.
Copper residues on the foliage bear a relationship to purple mite infestations as shown by the data in Table 1. The purple mite infestations were heavier in November where a neutral copperoil emulsion combination was applied in April than where a neutral copperwettable sulfur was applied at the same time. Analyses (5) of the copper residues* on the leaves showed that there was significantly more copper on the leaves where the copper-oil combination was applied and a higher mite population resulted. It should be emphasized here that the figures in the table represent only external copper. In the opinion of the authors, it is this .external copper residue which influences purple mite infestations.

0 Made by C. R. Stearns, Associate Chemist, Citrus Experiment Station.


THE PURPLE MITE AND ITS CONTROL













Copper Deposit' Percent Leaves


Copper Spray Dates of
Plots Combinations Summer
Applied May 6 Oil Sprays
5
2 3 Copper-W. Sulfur'
2
20 Copper-Oil'


THOMPSON AND GRIFFITHS: PURPLE MITE CONTROL


TABLE 1.
A RELATIONSHIP OF COPPER DEPOSITS ON LEAVES TO PURPLE MITE INFESTATIONS
SIX MONTHS AFTER THE COPPER APPLICATIONS.


on Foliage Infested with
mcg/crn2 Av. Purple Mites Av.
1.6 10
1.9 1.8 6 8.0
3.7 67
3.0 3.4 51 59.0
1.7 23
2.7 2.2 27 25
3.7 73
4.3 4.0 55 64
2.5 2
1.2 1.8 10 6.0
3.3 64
4.1 3.7 63 63.5
2 1
1.8 1.9 1 1
5 11
4.7 4.8 11 11


Copper-W. Sulfur


June 3 June 16 July 14 July 14 Aug. 4


19 Copper-Oil
12
30 Copper-W. Sulfur
3
21 Copper-Oil


Copper-W. Sulfur


22 Copper-Oil Aug. 4
Neutral copper (W' metallic Cu) G' 3-100 + w 2 Proprietary copper-oil emulsion (a) 2 gallons-100.
3 Copper analyses made by C. R. Stearns, Jr.

Parathion has been used as an insecticide f or the control of scale insects and mealybugs during 1949 and 1950 and some growers are of the opinion that it is a factor in increases of purple mites., Following the summer sprays for scale control it was found that purple mites were more numerous after an application of parathion than after an oil spray. Parathion killed the active mites, but it did not kill the eggs nor did the residue on the leaves and fruit remain toxic long enough to kill the young mites as they hatched. By comparison, an oil emulsion spray killed the active mites as well as the eggs. Thus, if there is an infestation of purple mites in the grove when an application of .parathion is made, it may be expected that mites will again be present within a week or two after the application.
The parathion situation may be further complicated by the use -of almost all other sprays or dusts. In the sum-


ettable sulfur 12 -100.


mer of 1950, observations at seven locations in Polk County demonstrated some of the interactions to be expected when different spray programs are used. The data are presented in Table 2.
From these data and other data not shown here, it would seem that the use of copper, zinc and sulfur are major factors influencing summer and fall purple mite infestations and that parathion is a minor factor. The average purple mite infestations were highest in plots where copper, zinc, lime and wettable sulfur had been applied as a post-bloom spray and followed with sulfur in the summer. Where nothing but sulfur sprays or sulfur dusts were used throughout the season the mite populations were higher than where parathion was used and much higher than in the unsprayed trees. The lightest infestations were in the plots sprayed with oil emulsions and in the untreated plots. However, it should be







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


TABLE 2.
SUMMER PURPLE MITE INFESTATIONS FOLLOWING VARIOUS SPRAY PROGRAMS IN SEVEN GROVES.


Post-Bloom Application


Percent Infested Leaves Summer 1 2 3 4 5 6 7
Application Aug. Aug. July July Sept. July July Averages
23 15 26 26 16 2 13


Copper, zinc, lime, sulfur Oil emulsion 2 6 2 0 2 2.4
Copper, zinc, lime, sulfur Parathion1 36 24 26 32 10 25.6
Copper, zinc, lime, sulfur Sulfur 53 23 66 90 58.0
sulfur Parathion 24 24.0
sulfur Sulfur 39 46 37 28 37.5
No sprays or dusts 16 5 2 10 0 2 1 5.0
Wettable sulfur 10-100 was combined with parathion.


noted that during the spring, all plots, including the untreated ones, were heavily infested.
Although spray residues may affect purple mite infestations, the type of weather still appears to be the dominant factor in influencing widespread mite populations. Lime-sulfur, wettable sulfur, sulfur dust and compounds of copper and zinc have been used over wide areas in the state for many years and generally heavy infestations have been the exception rather than the rule.
Miticides
If purple mites continue to be a problem during the spring and summer months it will be desirable to have a miticide that can be used safely during periods when succulent foliage is present and during warm weather. This problem will be intensified by the substitution of other scalicides for oil emulsion. During the past two years several new insecticides have been tested for the control of purple mites and they, along with the DN compounds, are discussed in the following paragraphs.
DN Dry Mix which contains 40% dinitro-o-cyclohexyl phenol, is still one of the most satisfactory miticides on the market but it is not safe to use when there is succulent foliage present or when the weather is hot.


DN-111, a preparation containing 20% dinitro-o-cyclohexyl phenol, /dicyclohexylamine salt applied at 11/4 pounds per 100 gallons is as effective as DN Dry Mix at 2/3 of a pound. It can be combined with the same type of spray materials that are used with DN Dry Mix and is not so toxic to young foliage as DN Dry Mix. DN-111 is slightly more expensive than DN Dry Mix per 100 gallons of dilute spray but it is within the economic range for grove use.
In 1947, Thompson (4) reported that Neotran, which contains 40% bis(p-chlorophenoxy) -methane, was effective in killing purple mites. Repeated tests have been made with this material and it has been found to be effective at 11/2 to 2 pounds per 100 gallons of spray. It appears to be compatible with all of the materials, including limesulfur; now used as sprays on citrus in Florida. It is one of the few miticides on the market at the present time that is effective when mixed with highly alkaline solutions. No foliage injury has been observed with this material when it was applied in the spring on succulent foliage or during the summer months. The limiting factor of Neotran is the cost, which at the present time is approximately 80 cents per pound. Thus, at two pounds per 100 gallons the cost







THOMPSON AND GRIFFITHS: PURPLE MITE CONTROL


of 100 gallons of dilute spray would be $1.60 or $8.00 per for a 500 gallon tank.
Another promising material, designated here as K-6451, is a wettable powder containing 50 percent chiorophenyl, p-chlorobenzene sulfonate. This material does not result in a high initial kill, but 7 to 10 days after the application, very satisfactory control has resulted. The period of control with this material was somewhat longer than that obtained with DN Dry Mix. However. the period of control with K-6451 was not as long during the warm spring and summer months as it was during the cool months from November to February. The minimum concentration for good control has not been determined but it will probably be 1 to 2 pounds per 100 gallons. It appears to be similar to DN in its compatibility with spray materials. To date no injury has been observed where it was applied to succulent foliage or when it was applied during the summer months. Taste tests of the fruit as well as further experimental work on compatibility and control will be needed before this material is released for the public use. At the present time there has been no information released on the probable cost of this material.
Aramite, a 15 percent mixture of beta-chloroethyl-beta- (p-tertiary butyl phenoxy) -alpha-methyl ethyl sulfite, has shown some promise as a safe miticide to use during the spring and summer months. On an average this material has not been as effective as DN, Neotran or K-6451. Aramite, like all other materials tested, was not as effective during the summer months as it was during cooler weather. It was found to be compatible with most materials used as sprays on citrus, but it was not tested with highly alkaline materials. No injury has been observed on succulent foliage where this material was used nor has there been any injury fol-


lowing sprays applied during June,'July or August. The present cost of Aramite is also comparatively high.
Other materials tested in a limited number of experiments included a 50 percent mixture of ,p-chlorophenyl phenyl sulfone and EPN, a material containing 27 percent of ethyl para, nitrophenol, thionobenzenephosphonate. Both of these materials appeared safe to use on succulent foliage and during warm weather but further tests are necessary to determine their effectiveness as a miticide.
It is interesting to note that where the sprays were applied in April or May the period of control was not so long as where the same materials were applied in November. It is quite possible that one of the factors which shortened the period of control was reinfestation of mites from adjacent properties. The plots sprayed in April and May were adjacent to blocks that were heavily infested with mites and there were indications in some experiments that adult mites migrated into these plots within 5 to 6 days after the applications. In one experiment no living mites were observed 3 days after a thorough application of an effective miticide. In comparison, the untreated plots were 100 percent infested. Four days later another examination was made and an average of 9 percent of leaves on the sprayed trees were infested with adult mites. It would thus appear that migration of adult mites took place because mites cannot develop from the egg to the adult stage within four days. In two other experiments conducted during the spring months it was found that adult mites made their appearance 5 to 6 days following an effective miticide where no mites were found 3 days after the application.
In Table 3 are recorded some of the results obtained with the most promising materials tested. It is desirable







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


TABLE 3.
COMPARISONS OF CONTROL OF PURPLE MITES WITH VARIOUS MITICIDES.

Materials and Concentrations in Pounds Figures Express Percent Infested Leaves
per 100 Gallons Pre- Nov. Dec. Dec. Jan. Feb.
Spray 12 1 80 19 10
Sprayed November 7
DN Dry mix .66 lbs. 92 0.2 0.0 0.0 1.4 9.5
K-6451 1.50 " 94 4.1 0.0 0.1 0.0 6.5
Neotran 1.50 " 94 0.0 '0.0 0.4 2.1 21.5
Aramite 1.50 "1 77 0.0 1.2 4.8 12.2 81.5
Nov. Nov. Dec. Jan. Feb.
Sprayed November 11 1 28 22 7 10
DN Dry mix .66 lbs. 15 0.0 0.8 3.8 33.5
K-6451 1.50 " 18 0.0 1.2 10.2 19.4
Neotran 1.50 " 14 0.0 0.0 2.9 32.1
Aramite 1.50 " 15 3.0 1.1 8.3 50.3.
Jan. Jan. Feb. Feb.
Sprayed January 11 5 16 4 28
DN Dry mix .66 lbs. 32 0.0 6.2 5.0
K-6451 1.50 " 42 13.0 1.9 1.5
Neotran 1.50 " 34 0.0 13.8 22.5
Aramite 1.50 " 48 0.6 19.0 10.5
No treatment 36 28.1 40.0 26.0
March April April April May May Sprayed April 3 80 7 18 27 5 23
DN Dry mix .66 lbs. 33 1.7 1.0 0.0 19.1 60.0
K-6451 2.00 " 21 2.5 0.0 0.0 .4 2.5
Neotran 2.00 " 47 0.0 0.0 0.0 4.1 29.0
Aramite 2.00 " 4 6.0 1.0 1.2 27.1 61.0
No treatment 5 5.0 15.0 15.0 30.0 57.0
April April May May May
Sprayed April 17 13 21 2 8 23
K-6451 1.5 lbs. 10 0.0 2.0 18.0 45.0
K-6451 2.0 " 12 0.0 0.0 01.0 53.0
No treatment -33 45.0 77.0 88.0 97.0


to do. further experimental work with all. of. these new miticides, not only -to test their effectiveness, but also to test their safety on foliage and fruit.

Timing and Application, of Sprays
The period of control of purple mites does not depend entirely on the miticide used. One of the cardinal prerequisites to obtaining a long period of control is to apply the miticide before a high per-


centage of the leaves become infested. This is illustrated in the following discussion.
Although it is now well known that parathion is not an outstanding material for the control of purple mites, light infestations in four plots were kept at a low level for two months where parathion was included in a dormant spray at 1 pound of 15% material per 100 gallons of mixture.








THOMPSON AND GRIFFITHS: PURPLE MITE CONTROL


When the application was made about 2 percent of the leaves were infested, whereas two months later an average of 8 percent of the leaves were infested in the parathion plots as compared to 32 percent infested leaves where parathion was omitted. The parathion had killed the few active mites, and since there were very f ew eggs present at that time, the mite population did not build up in those plots until May.
The intensity of the infestation at the time of spraying influenced the degree of infestations at a later date. Thus, in experiments where duplicate plots were used, and where there was a diff erence of 20 to 30 percent in the original infestation at the time of spraying that difference was still apparent at the conclusion of the experiment although the level of population had been substantially reduced by all treatments. This was true in 88 percent of the duplicate plots. For instance, on January 3, Plot A had 18 percent of the leaves infested and the duplicate, Plot B,"had a 43 percent infestation. Three months after the application, Plot A had 4 percent of the leaves infested compared to a 35 percent infestation in Plot B. This comparison is made to stress the importance of treating groves in October or November when the mite population is at a low level, and treating again in January or February. Mite populations will thus remain -at a low level. through the late winter and spring months when grove conditions


are likely to be unfavorable for spraying because of dry weather and the
presence of succulent foliage.
If dusting is practiced it is especiallY important to make the application before the mite population reaches a high level. If a high percentage of the leaves are infested when a dust is applied, a second application should be made within a week or ten days to bring the numbers down to a point where a reasonable period of control can be obtained.
Thorough coverage is of prime importance. None of the miticides are considered fumigants and direct contact is necessary for satisfactory control. The type of coverage that is usually made for rust mite control is not thorough enough for purple mite control. Special care should be taken to cover the tops of the trees where the heaviest infestations are usually found.
LITERATURE CITED
1. HOLLOWAY, J. K., CHAS. F. HENDERSON and
HORACE V. NMcBuarE. Population increases of citrus red mite associated with the use of sprays containing inert granular residues. four. Econ.
Ent. 35 (3): 348-350. 1942.
2. TxhOMPsON, W. L. Cultural practices and their
influence upon citrus pests. four. Econ. Rnt.
32 (6): 782-789. 1939.
3. Tt~ompsoN, W. L. Progress report on purple
mite and its control. Proc. Fla. State Hort. Soc.
57: 98-110. 1944.
4. TnormPSON. W. L. and J. T. GRIFFITHS, JR.
New insecticides and their application on citrus.
Proc. Fla. State Hort. Soc. 60: 86-90. 1947.
5. Tssomeso, W. L. Combined control, of scale
insects and mites on citrus. Fla. Agri. Exp. Sta.
Ann. Rept. 71-73. 1948.







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


AVERY S. HOYT, Chief
Bureau of Entomology and Plant Quarantine
Washington, D. C.

As everyone knows, injurious insects and plant diseases constitute serious obstacles to agricultural production. This seems to be true the World over. Fortunately or unfortunately the destructive organisms that cause greatest losses in one part of the World may not occur in others. This feature of their distribution gave rise many years ago to efforts in various parts of the World to set up restrictions aimed at protecting the agricultural industry of one country from plant pests known or believed to occur in another. These restrictions which we call quarantines were in effect in some parts of the World long before the United States first gave consideration to its need for similar plant-pest protection. By 1912 when this country first enacted legislation for this purpose many injurious insects and plant diseases had found their way here and had become established. As fruit and vegetable production is particularly vulnerable to attack by these organisms, many States were united in urging upon Congress the need for action. The State of Florida, because of its tremendous production of these articles, was and continues to be one of the leaders in urging the need of some means of screening the arrival here of additional plant pests. Florida is particularly vulnerable because of climate, crop specialization, geographical location, and proximity of serious insect pests and plant diseases within easy reach of Florida ports by air and water.
In 1912 Congress passed the Plant


Quarantine Act authorizing the Secretary of Agriculture to promulgate rules and regulations to safeguard the importation into this country of nursery stock, fruit, and other plant products. It has been the policy of the Department to take such action on a biological basis. Care has been taken to avoid the use of this authority in furtherance of economic or competitive conditions. Quarantines that have been promulgated have been aimed at specific subjects and have been accompanied by minimum restrictions consistent with the objective of protection from insect pests or plant diseases not known to occur or to be widely distributed within this country. The restrictions issued under this legislation by the Secretary of Agriculture have varied during the years, depending to some extent on the nature of the material which formed the large percentage of the imports, upon information with respect to pest risks, and upon the advisability of the application of methods of treatment to safeguard the importations.
Much of the information on which plant quarantines have been put into effect through this authority by the Secretary of Agriculture has been accumulated by the Bureau of Entomology and Plant Quarantine. In the case of plant diseases the basic information has frequently been furnished by the Bureau of Plant Industry, Soils, and Agricultural Engineering. In the case of every foreign plant quarantine the objective has been to get the most accurate knowledge possible with respect to the distribution of the insect or disease, ways in which it might be transported, materials on which it would be most likely to be carried, the possibility of destroying the organism through the


FLORIDXS STAKE IN PLANT QUARANTINE ENFORCEMENT







HOYT: PLANT QUARANTINE ENFORCEMENT


application of treatments at destination or port of entry, and the probable damage likely to occur in this country in the event of its introduction. In general the policy on which quarantines have been established has been to consider the biological necessity to exclude a specific plant pest and then to provide such restrictions on the importationof the plants or parts thereof which serve as the host as will most adequately protect domestic agriculture.
With the passage of the Plant Quarantine Act the responsibility for dealing with foreign quarantine problems was placed on the Federal Government.
Plants and other restricted commodities imported into this country are considered to be in foreign commerce until actually arrived at the point of destination. It has been held by legal advisers of the Department that the States do not have authority over such commerce until delivery to the ultimate consignee. At that point under the State police powers the State plant quarantine officials have authority to make inspections and take appropriate action.
As a result of research, much of which has been done by the Bureau of Entomology and Plant Quarantine, means have been developed to destroy injurious insects on various types of commodities through the use of commodity treatments. These methods of treatment are required as a condition of entry for many different kinds of plants and plant products. Temperatures, both hot and cold, for specified periods of time, poison gases, and various insecticidal dips may be required. These methods of treatment may be prescribed in some cases after inspection as a precaution and in some cases are required as definite conditions of entry. In the case of fruits originating in countries where fruit flies of various species are known to occur, the timetemperature treatments are required as


a condition of entry. There are 3 general procedures under which these treatments may be applied: (1) At port of entry under the supervision of representatives of the Bureau; (2) in the country of origin and at the present time this is applicable only to Mexico where arrangements have been made whereby representatives of the Bureau may do such work at the expense of the exporters, and (3) the application of the treatment in transit. It has been found that the temperature and the exposure duration are not the same for all species. More extreme temperatures and longer time intervals are needed for some. These commodity treatments are effective when properly applied and with experience it has been possible to simplify and standardize equipment and procedures to make their application more effective and less costly.
One of the serious problems is our inability to recognize the symptoms of, or to control, that class of diseases which is caused by the presence of a virus. In the inspection of nursery stock entering the United States it has been found impossible through inspection at the ports of entry to be sure as to the presence or absence of a number of virus diseases. It was primarily because of the need to strengthen our protection against virus diseases accompanying imported nursery stock that led to the revision of Quarantine 37, the Nursery Stock, Plant, and Seed Quarantine, a few years ago providing the requirement of growing the material for a specified period of time in postentry detention to permit inspection during one or more growing seasons.
It is recognized that postentry procedures leave something to be desired. It is not the best procedure to bring plants into this country, establish them in our soil, and then await the possibility that they may have brought some serious infestation or plant disease. It is







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


believed, however, that inspection during the growing season offers the best chance to detect the presence of virus diseases in plants. It is hoped that it may be possible to arrange that our inspectors may examine the material in the country of origin. Inspection of the growing material in the nurseries abroad and the rejection there of material which appears to threaten our welfare would seem to be more practicable and effective. If the means and the trained men were available to inaugurate such a program it would be necessary that there be an invitation from the countries involved to make the inspections within their borders. Some progress has been made in this direction. Inspectors of the Bureau have visited a few countries on specific errands involving the inspection and application of treatments for the safeguarding of materials destined to be shipped to this country. It is believed the recognition of the advantages of this method of procedure will grow and it is hoped that by this means a satisfactory substitute for the present system of postentry inspection may be developed.
A step in the direction of more effective international cooperation was taken when the United States was represented at the recent International Conference on Plant Quarantine Regulations convened by the Netherlands Ministry of Agriculture at The Hague. This initial conference resulted in a draft of an international agreement which is now before the countries concerned for consideration. Its provisions include: Statements of Purpose and Responsibility; Supplementary Agreements under the Convention; Establishment of National Organization for Plant Protection; Requirements in Relation to Exports; Requirements in -Relation to Imports; International Cooperation; Amendment of Convention; Settlement


of Disputes; Treatment of Non-adhering Countries; Ratification and Adherence, and Effective Date. From participation in this Convention it is believed the United States should benefit. The question has been asked whether this would mean that the Federal inspectors would have to accept certificates from officials of other countries. The answer to this is no. We do not have to accept their certificates now and the proposed standardization would not modify this authority. To my knowledge no agency of the Federal Government has sought to influence decisions of the Department of Agriculture based on biologically sound requirements for imported plant material. From the standpoint of this country it is believed international discussions such as this International Agreement contemplates may afford us a chance to establish relations with other countries which it is hoped may lead to the opportunity for our inspectors to work with their inspectors in the nurseries from which shipments are made to the United States. It is our hope that this would furnish some first-hand information about the conditions surrounding the material which is offered for entry into this country.
In recent years plant pests have been transported over long distances as never before through the movement of airplanes. Planes taking off in one part of the World and landing in another all between sunrise and sunset means that living insects may be transported and become established as has not been the case with slower transportation. Florida has occasion to fully understand the consequences in terms of dangers of plant pest distribution due to the enormous increase which has taken place in international air transportation. The burden of inspection which has fallen on the Florida State Plant Board in Florida and on the







HOYT: PLANT QUARANTINE ENFORCEMENT


Bureau of Entomology and Plant Quarantine throughout the country is in direct proportion to the expansion in this activity. In the f irst 9 months of 1950, 14,500 planes from foreign ports were inspected in the State of Florida by State and Federal inspectors cooperating.
There are numerous instances of the long-distance transportation of living insects by means of airplanes. Evidence is abundant that some injurious species have been established in distant parts of the World through this means. It seems reasonable to believe that the danger of the long-distance dissemination of injurious insects through air travel is likely to increase unless definite measures are taken to prevent. With this objective experiments are being conducted to develop insecticides to be applied to interiors of airplanes. Planes from Hawaii are sprayed before departure from the Mainland, careful inspection is being made of foreign planes on arrival at the airports in this country, and representations have been made to the agricultural officials of other countries looking toward their adoption of precautions which might be of protection to them as well as to us.
Florida is interested in the status of the diseases of citrus known as mal secco, quick decline and tristeza, and of the infestations of the citrus blackfly in Mexico and the oriental fruit fly in Hawaii.
In Mexico work against the citrus blackfly has been carried on in cooperation with the Mexican Department of Agriculture and with committees of growers organized in some of the principal fruit-growing States of that country which have actively participated in the suppressive program. Infestation was found early in 1950 as close to the border as Matamoros just across the Rio Grande from Brownsville. This was a light infestation found on one


tree on a property within a f ew doors from the bus station which leads to the belief that the insect may have reached that point in connection with bus travel from interior points of Mexico. That infestation is believed to have been eradicated and no recurrence has been found to date despite frequent and careful inspections. Bus travel is interrupted at the border as the vehicles themselves do not cross. The question whether the insect may be carried as a hitch-hiker on traffic crossing the line, however, is under investigation. This involves the possibility of spraying such vehicles in connection with their crossing and search is being made for a suitable spray.
Infestation now occurs in the City of Monterrey where spraying is being carried on at all points where living citrus blackflies are known to occur. Other infested areas in Mexico where suppressive measures are being applied include Victoria and one or two points between Victoria and Monterrey; also in the vicinity of Valles in the State of San Luis Potosi about 300 air miles south of the border where rather heavy infestations of the citrus blackfly have occurred over a period of several years. At that point a Bureau spray program is in progress on selected properties to demonstrate that fruit production can be restored if proper sprays are applied at the right time.
On the West Coast the infestations which were found in the vicinity of Guaymas and Empalme have been subjected to several spray applications. In this area it will be recalled the first suppressive measures were put into effect by the fruit growers of Arizona and California who contributed funds and sent their own men to supervise the program. In this initial effort the Bureau cooperated by determining the limits of infestation to the northward in cooperation with the Mexican Depart-







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


ment of Agriculture. The number of infested properties has been steadily reduced as well as the intensity of the inf station.
In Cuba the citrus blackfly was found to be readily controlled by parasites. These same insects taken to Mexico and liberated there have not proven to be equally effective. It will be recalled that there was an inf station of the citrus blackfly in south Florida on Key West a number of years ago. Resort was not made to natural control at that time as it was deemed desirable to completely eradicate the infestation if possible and after a spray program of some duration in which the Bureau cooperated with the State Plant Commissioner, it is believed the infestation was completely wiped out. Parasites were imported into Mexico during the season 1948-49 from Malaya. There was difficulty in making these introductions because the infestations were on citrus in that country. Because of the danger of bringing citrus canker infested material to Mexico the procedure was to take potted citrus trees from Mexico to Malaya, there inf est them with the citrus blackfly, then introduce the parasites, cage the infested plants and ship by water. Little success attended these efforts, perhaps because of the long period of time involved. In the season of 1949-50, parasites were collected in India. In this instance it was possible to secure infested non-citrus leaves carrying the parasites. These were shipped at frequent intervals by air and a large amount of the material came through successfully. Sufficient time has not yet elapsed to permit an evaluation of the effectiveness of these beneficial insects. It would very greatly lessen the concern of the fruit growers of this country if biological control of the citrus blackfly in Mexico should prove to be effective.
With respect to the oriental fruit fly


situation in the Hawaiian Islands, a very comprehensive research program was undertaken in the beginning of the fiscal year 1950 with funds made available by the first session of the 81st Congress. The work was divided into five main projects:
(1) Biology and habits of the fruit
fly
(2) Treatment of agricultural products grown in infested areas so that they may be transported
safely into uninfected areas
(3) Search for insecticides that will
kill the insect
(4) Large-scale control and eradication studies
(5) Biological control
The work in these lines of investigation has been vigorously prosecuted. The importations of beneficial insects have been very encouraging. A number of the imported species have been recovered from various parts of the Islands showing that they have become definitely established and at some points the parasitization has reached an encouraging level. Active cooperation in the studies directed against the oriental fruit fly is being received from California and from Hawaii. The California State Department of Agriculture and the Citrus Experiment Station of the University of California have been actively cooperating. They have loaned men to this undertaking and accepted responsibility for certain activities associated with the general program. The Board of Agriculture and Forestry of Hawaii and the Hawaiian Experiment Station are also valued cooperators. The Pineapple Research Institute and the Hawaiian Sugar Planters Association Experiment Station are also giving valuable assistance.
Airplanes leaving Hawaii f or the Mainland are given preflight inspection and are also sprayed in an effort to







GRIFFITHS, STEARNS AND THOMPSON: CONCENTRATED SPRAYS


prevent hitch-hiking fruit flies. Careful inspection and treatment of products moving to the Mainland are required. California has been carrying on a trapping program in order that if the fly should find its way there the infestation would be discovered while still in the incipient stage. The results of this trapping program have thus far been negative in California.
Plant quarantine policies and procedures have been undergoing rather frequent and rapid changes. Progress in the development of insecticides, additional information as to the distribution and abundance of plant pests, and the possibility of long-distance dissemination all have contributed to this situation. In this country the State plant quarantine officials, by working together, have made notable progress in simplifying, coordinating, and stream-


lining the State quarantines and procedures which affect interstate shipments of plants and plant products. Their organization s-the regional and the National Plant Boards-have afforded a medium for free friendly discussion of their mutual problems. It is believed that progress in dealing with other countries is possible through similar means. Long strides in this direction have been made in our dealings with our neighbors, Canada and Mexico. Working at greater distance there has been excellent ground work laid for further cooperative relationships with Argentina, Australia, and Holland. Better understandings lead to better cooperation. From our point of view better cooperation means fewer plant pests accompanying agricultural imports and that is the aim which must be kept ever before us.


JAMES T. GRIFFITHS, C. R. STEARNS,
AND W. L. THOMPSON
Florida Citrus Experiment Station
Lake Alf red

During the past few years, spray machines have been developed for applying concentrated sprays to deciduous fruit trees. The purpose of such sprays was to apply the required amount of the active ingredient to the tree with a minimum amount of water. By reducing the actual gallons of spray per tree the cost of application may be decreased both by eliminating the hauling of water and by reducing the time required to refill the spray tank. If the spray mixture is concentrated four times the ordinary strength, then there is a saving of 75% in the amount of water hauled, and a similar amount of


time saved in filling the tanks. With concentrated sprays such a low volume of fluid is delivered per tree that no run-off or dripping occurs. The purpose of this paper is to present results on the use of concentrated sprays on citrus in Florida.*
The first concentrate type sprayers to be used on citrus in Florida were tested by King and Griffiths (2) in 1947. Two machines (Buffalo Turbine and Hessian Microsol Generator) were tested in the control of the American grasshopper in citrus groves. These machines gave very poor insecticide distribution on the tree. In spite of this, relatively satisfactory grasshopper control was obtained. However, it was concluded that

*For those readers who desire infOTinition concerning the history and t1wory of concentrated sprays reference is suggested to a thesis by R, M. Pratt (6). . . i


POSSIBILITIES FOR THE USE OF CONCENTRATED
SPRAYS ON CITRUS IN FLORIDA







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


this type of machine would not be practical for the control of sedentary citrus pests.
At the start of the 1949 spray season, a Hardie mist sprayer" was loaned to the Citrus Experiment Station. This machine is powered by a 45 h.p. gasoline engine. Air is delivered to only one. side at the rate of approximately 20,000 cubic feet of air per minute and at a velocity of 110 miles per hour. The pump capacity is 18 gallons per minute, and the pressure is maintained at approximately 400 pounds. The principles involved in the design of this machine were developed at Cornell University (4,5,6). The basic design is such that the air is driven up into the tree, and the desired spray particle size is produced by the use of high pressures.
Also in 1949, the Speed Sprayer Company began developmental work on modified nozzles to be used in a Speed Sprayer (Model 36) for the delivery of concentrated sprays. In contrast with the Hardie sprayer, a Speed Sprayer delivers approximately 44,000 cubic feet of air to two sides or 36,000 to one side, and the velocity varies between 90 and 105 miles per hour. It is powered by a 110 h.p. gasoline engine. A centrifugal pump is employed to deliver spray solution at a pump capacity of 150 gallons per minute at 65 pounds pressure.
A number of other concentrate sprayers are being offered for sale in other parts of the United States. One of these, the Lawrence Mist-o-Matic Sprayer, was tried in the summer of 1950. The distribution of spray materials appeared to be satisfactory in the tops and on the off-sides of the trees, but the lower 6 feet of the tree adjacent to the sprayer were not covered. This machine will require considerable modi**Mist sprayer as defined by Pratt (6) is a sprayer to be used for the application of concentrated sprays.


fiction in order to make this a practical sprayer for use in citrus groves.
During 1950, some caretakers have successfully applied double concentrations of toxicants at half gallonage with the conventional nozzles in a Speed Sprayer. Such semi-concentrates represent a compromise between dilute and concentrated sprays, but they represent a trend in the direction of concentrated mixtures.
The work reported here deals with experiments conducted during the 1949 and 1950 seasons using the Hardie sprayer and the Speed Sprayer. In most cases, the spray was applied at oneeighth the gallonage and at six times the concentration normally used. This meant that three-fourths as much material was being applied per tree as with a dilute spray. Previous work on apples had indicated that less material was necessary when no drip occurred (1,3).

Results
Mite Control.-During the 1949 and 1950 seasons the two concentrate spray machines were compared with a dilute Speed Sprayer in an orange grove near Auburndale. The dormant spray (zinc, DN, sulfur), the post-bloom spray (copper and sulfur), and summer and fall sulfur sprays were applied with this machinery. The summer spray for scale control was an oil emulsion applied by a hand machine. Careful checks were made of purple mites and' rust mites throughout the two years. There was no significant difference in the control of these pests that could be attributed to the use of concentrate sprays. In similar small scale tests, rust mite and purple mite control was as satisfactory with concentrated as with dilute sprays.
Scale Control.-Three rather extensive scale control experiments have been performed. In 1949, a parathion experiment was carried out in a grove near









































JUNE 30, 1949.
% Mortality Avg. of Two Plots 98 99 99 100
99 97


1.0 3.0 .031 93
1.0 3.6 .054 80
1.5 2.7 .042 98
Hardie Sprayer 1.5 2.9 .068 97
2.0 2.5 .052 100
2.0 2.5 .078 97
Speed Sprayer 1.0 25.0 .062 99
Dilute 1.0 25.0 1.3% oil 100
Pressure Sprayer . 18.0 .041 99
Dilute . 17.0 1.37o oil 99


GRIFFITHS, STEARNS AND THOMPSON: CONCENTRATED SPRAYS


Auburndale. Parathion was used as a concentrated material and compared with both a 1.3 percent oil spray and a dilute parathion spray, both of which were applied by hand as well as by Speed Sprayer. Duplicate plots were used in all experiments.
The concentrated material was applied with the same nozzle settings in all plots, but the machines were driven at three speeds, which resulted in more gallons being applied per tree at the slower speeds. The concentration of inseeticide was so regulated that the comparable amounts of parathion were applied per tree. Half of the plots sprayed with concentrate had the parathion concentration arranged so that only threefourths of the standard quantity was used per free. The results of this experiment are shown in Table 1. In one of the Hardie plots, purple scale control was unsatisfactory, apparently due to nozzle stoppage and to the fact that distribution of the insecticide was poor. It was concluded from this experiment that there was no significant difference in


control caused by the use of'dilute as compared to concentrate sprays, by the use of the Hardie Mist Sprayer versus Speed Sprayer, or by the use of 25 percent less parathion as compared to the usual amount of parathion.
Another scale control experiment was performed at Lake Placid in 1949. This compared dilute sprays in a Speed Sprayer with concentrated sprays in both the Hardie Mist Sprayer and the Speed Sprayer. The standard application was supposed to consist of 28 gallons per tree of a 1.3 percent oil spray. All sprays were applied at the rate of 1 mile per hour. Three nozzle sizes were used in both the Speed Sprayer and the Hardie Sprayer. This was done in order to vary the amount of water applied per tree. The concentration of oil used in the Speed Sprayer was arranged so as to deliver the same amount of oil per tree as would be applied if a 1 percent oil were used at 28 gallons per tree. For the Hardie Sprayer, three oil concentrations were used which were equivalent to the oil


TABLE 1.
SUMMARY OF PURPLE SCALE CONTROL IN GROVE AT Speed Cal./
Mi./Hr. Tree
1.0 5.0
1.0 5.2
Speed Sprayer 1.5 3.5
Concentrate 1.5 3.3
2.0 2.3
2.0 2.3


AUBURNDALE ON
Lbs. Parathion/Tree
.032 .073
.049 .071
.042 .064













































5.3 6.1 5.0
4.4 4.4 4.9 3.9 3.9 3.2 12.9 9.5 6.2


Speed Sprayer


TABLE 2.
A COMPARISON OF CONCENTRATE AND DILUTE SPRAYS WHEN OIL WAS USED TO CONTROL SCALE AT LAKE PLACID IN 1949.


Speed Mi./hr.
1.5


1.5 1.0 10.3 3.1 38 79 90
1.0 7.0 3.1 50 93 100 1.0 4.5 3.3 88 90 100 1.0 1.3 23.0 2.3 28- 77 90


FLORIDA STATE HORTICULTURAL SOCIETY, 1950


that would have been applied in the 1.3, 1.0 and a 0.8 percent oil emulsion, all used at 28 gallons per tree. The results are shown in Table 2. The gallons of spray per tree, the actual pints of oil per tree, and the oil deposit on the foliage is shown. There were significant correlations between the amount of oil sprayed per tree and the amount deposited per unit leaf area. Both of these factors were, in turn, significantly correlated with purple scale control. Red scale control was generally more satisfactory than purple scale control, and as a result, the former did not show correlation between the rates of application and the


percent control It was concluded that the amount of oil deposited evenly over a tree was the important factor, and it appeared that it did not make any difference what strength or gallonage was applied so long as sufficient oil was spread uniformly over the leaf and twig surfaces
Leaf drop was not severe following this spray. However, where the concentrate sprayer turned around the tree at the end of a row, the terminal tree had severe leaf drop. This suggested the fact that with oil sprays -at least, the sprayer should come out of the grove, drive past the end tree, and then cut off the spray before turning around. This


Mortality
Oil Deposit Purple Red Mcg./Cm2 Scale Scale
57 60 80
36 37 87
36 70 97
46 72 97
43 73 100
60 86 91
59 65 96
43 77 96


Oil Equivalent
1.3 0.8 1.3 1.0 0.8 1.3 1.0 0.8


Cal. of Spray/Tree
7.4 9.3 6.7 6.8 8.6 6.0 5.3 5.0


Pts. Oil/ Tree 2.2 1.6 2.7 2.3
2.0 3.8 2.7 1.8


Hardie Mist Sprayer


1.5 1.3
1.0 0.8 1.3 1.0 0.8 1.3 1.0 0.8 1.0 1.0
1.0 1.0







































TABLE 3.
PURPLE SCALE CONTROL AND LEAF DROP FOLLOWING THE USE OF DILUTE AND CONCENTRATED SPRAYS ON JULY 7, 1950.

Gal. % Reduction Leaf Lbs. Reducli. Leaf
Machine Oil/Tree Drop Parathion/ of Drop*
Purple Scale Tree Purple Scale
.20 80 64 .059 80 5
Hardie Sprayer .23 92 56 .052 100 32
.29 75 78 .056 97 16
.36 77 118 .080 100 32
.29 91 52 .060 100 22
Hand Sprayer .34 92 40 .081 99 59
Speed Sprayer .33 96 39 .066 97 19
Dilute .29 82 56 .066 93 43
.24 91 63 .067 96 29
.31 84 33 .080 93 35
Speed Sprayer .25 89 94 .060 95 39
Concentrate .33 82 33 .057 97 34
.42 95 67 .072 95, 22
.31 90 93 .072 87 33
Based on total newly dropped leaves on 1/5 of the area under the tree on July 31.


GRIFFITHS, STEARNS AND THOMPSON. CONCENTRATED SPRAYS


would avoid excessive oil deposits and subsequent leaf drop on the end tree.
In 1950, oil emulsion and parathion sprays were compared in a grove near Auburndale. These materials were applied by hand with pressure rigs, as dilute sprays in the Speed Sprayer, and as concentrated sprays in both the Hardie Mist Sprayer and the Speed Sprayer. The results of this experiment are shown in Table 3. The basic spray was considered to be 25 gallons per tree of a 1.3 percent oil or parathion at 2 pounds of 15 percent wettable material per 100 gallons of spray. The concentrated sprays were designed to apply equal amounts of insecticide in one set of plots and only three-fourths as much in another set. Because of irregular delivery by both machines, no conclusions could be made regarding the rate of dosage. Purple scale control was satisfactory in all applications regardless of the method of application. There was more leaf drop -following oil than parathion and more with concentrated than dilute oil,


but in no instance was the leaf drop severe.
Fruit Grade in Packinghouse.-In
1949, representative samples of fruit from the experimental plots at Auburndale were checked in the packinghouse in order to compare grade as well as insect and mite injury on fruit. In this comparison, there was no difference either in grade or external quality which could be attributed to a difference in the methods of application. In other words, concentrated sprays appeared to have produced as satisfactory or as good quality fruit as that produced by dilute spray machinery.
Discussion
During 1949 and 1950 sufficient work with concentrated sprays has been performed to demonstrate that they will probably be practical for use on citrus in Florida. Lime-sulfur, wettable sulfur, DN, zinc sulfate and lime, neutral copper, oil, and parathion have all been applied successfully. However, before concen-







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


trate sprays can be generally used, a number of problems must be studied and solved. The grower will no longer be able to think in terms of how many pounds of material to use per 100 gallons of spray. Rather he will have to know how much copper is needed on a given size tree to control melanose, how much zinc sulfate is needed on a given size tree to maintain optimum zinc levels, and how much parathion per tree is needed f or scale control. As an example, it may 'take two-thirds of a pound of 15 percent parathion on a large grapefruit tree to control scales, and it may take only one and one-half pounds of sulfur to control the rust mites. In this case, parathion and sulfur will be used in a ratio of 4 pounds of 1517o parathion to 9 pounds of sulf ur. If three gallons are to be applied per tree, then 33 trees will be sprayed with 99 gallons and each 100 gallons of spray will contain approximately 22 pounds of 15 percent parathion and 50 pounds of sulfur. This example shows that considerable calculation may be necessary in order to figure out the proper amounts of material to use per tank of spray.
The gallonage to apply per tree poses another difficulty. In experimental work, one-eighth the normal gallonage has been used in most cases. It may be determined subsequently that still greater concentrations will be satisfactory, but, in any case, the gallons to be applied per tree will determine the amount of material per 100 gallons of spray. If the grower plans to apply 3 gallons and actually applies 31/2 gallons per tree, he will not only use an extra half gallon per tree, but also this will represent a 17 percent increase in material costs. With dilute sprays, a half gallon error resulted in less than a 5 percent increase in material costs. With concentrated sprays, small errors in gallons delivered per tree will result


in big differences in the amount of material applied per tree.
In the case of the Hardie Sprayer, gallonage is regulated by the aperture size in the spray disc and not by. the number of nozzles. Thus, the rate of delivery into the top or the bottom of a tree is also regulated by disc size. It will take considerable knowledge on the part of the operator to properly set the nozzle sizes and adjust the air flow baffles for proper distribution over the tree as well as for the proper gallonage per tree. Tall trees need larger nozzle sizes at the top and small trees need more spray concentration at the bottom.
In the case of the Speed Sprayer, gallonage can be regulated either by nozzle aperture size or by the number of nozzles. Since the number of nozzles will probably be less than one-fourtb the number now used with dilute sprays, distribution will again be a problem, as it will be difficult to determine which pipe is to hold 1 and which 2 or 3 nozzles.
None of these problems are insurmountable. Most can be solved by time and thought, but before attempting to use concentrated sprays a grower should be acquainted with the difficulties involved, and he should have sufficient information to be able to adequately determine the amount of material to use and the gallons per tree to employ.
The use of concentrated sprays on citrus can result in savings to the grower. Probably less insecticide will be needed per tree. Table 4 presents sulfur deposits for one experiment where the Hardie Mist Sprayer was compared with a Speed Sprayer delivering dilute sprays. The deposits are calculated on the basis of micrograms of sulf ur deposited on a square centimeter of leaf surface per pound of sulf ur applied to the tree. Thus, they dre a measure of the amount of sulfur which stuck to the







GRIFFITHS, STEARNS AND THOMPSON: CONCENTRATED SPRAYS 59

TABLE 4.
MICROGRAMS OF SULFUR DEPOSITED PER CM2 PER LB. OF SULFUR FROM
SAMPLES TAKEN FROM THREE LOCATIONS ON THE TREE.


Hardie Mist Sprayer Concentrated Spray On Side Off Side
35 42
33 49
25 26
34 46


Speed Sprayer
Dilute Spray
Top On Side Off Side Top
19 19 19 8
25 19 21 14
15 32 36 10
25 32 44 9
21 25 30 10


Four Duplicate
Plots

Avg.


leaf surface. The figures are for the sides of the tree adjacent to the sprayer (on side), the side between the trees (off side), and the tops. The concentrated spray deposited 25 to 50 percent more sulfur than did the dilute spray. This is similar to information from other sources (1,3). In the case of oil emulsion sprays this may not be true, but in all other instances there are definite indications that the amount of material can be reduced over that which is normally sufficient to dilute sprays.
In addition to material savings, there should also be operational savings. It will no longer be necessary to use one or possibly two supply units for an individual sprayer. Whereas a 500 gallon tank of dilute spray will spray possibly only 25 trees, 200 trees can be sprayed with a tank of concentrate. Therefore, one supply unit should be able to supply 2 or even 3 sprayers in a single grove. This represents a saving in spray labor as well as in the use of the machinery.

Summary and Conclusions
Concentrated sprays have been used experimentally during the 1949 and 1950 spray season on citrus in Florida. Two machines, the Hardie Mist Sprayer


and the Speed Sprayer, appear to offer good possibilities for use with this type of spray. In general, one-eighth the normal gallonage was used per tree. and indications were that with the possible exception of oil, less spray material could be used per tree than with dilute sprays. In comparative trials, the control of rust mites, purple mites, scale insects, and melanose have been as satisfy factory with concentrated sprays as with dilute sprays. It was concluded that the use of this type of spray should be practical on citrus in Florida.

LITERATURE CITED
1. BURRELL, A. B. 1950. Concluding remarks on
concentrate spraying. Proc. N. Y. St. Hart. Soc.
95:109-113.
2. KING, JOHN R. and J. T. GRIFFITHS. 1948.
Results of the use of concentrated sprays in
citrus groves in Florida. Fla. Ent. 31:29-34.
3. PARKER, K. C. 1950. Further studies on mist spraying. Free. N. Y. St. Hort. Soc. 95:105-108. 4. PARKER, K. G., R. M. PRATT, and L. R. BnowN.
1948. Spray duster for fruit trees. Farm. Res.
14:15.
5. PRATT, R. M. 1947. The development of the
new Cornell experimental spray-duster. N. Y.
State Hort. Soc. Proc. 92:132-140.
6. PRATT, B. M. 1950. Investigations of fungicide
deposits and fruit tree disease control by the spray-dust and mist spray methods as compared with conventional hydraulic spraying. Thesis on
file Cornell University Library, Ithaca, N. Y.







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


JOHN W. SITES
Florida Citrus Experiment Station
Lake Alfred

Introduction
For many years potash has been a major constituent in the fertilizer mixtures applied to citrus in Florida. The use of potash in modern amounts has seemed reasonable, for citrus soils in Florida are not well supplied with potassium containing minerals. There is consequently, only a minimum supply of potassium for utilization by growing citrus trees in Florida except as furnished in the form of fertilizer. Like nitrogen, potassium does not accumulate in these sandy soils (15) and much of that not absorbed by the roots of the trees is lost. Unlike nitrogen however, potassium deficiency symptoms are not quickly discernable under field conditions. A number of papers have been published covering one phase or another of the work on the use of potash on grapefruit at the Citrus Experiment Station and at this time it seems desirable to summarize these findings up to date. In this paper the symptoms which have been found to be associated with potassium deficiency in the field, and the effect of variable potash fertilization on the internal and external quality and on production of Duncan grapefruit are presented and related papers reviewed.

Literature Review
A study of the literature dealing with potassium nutrition of citrus reveals that a large number of symptoms have been associated with potassium deficiency. It should be kept in mind that


in most cases these symptoms have been observed where citrus was growing under artificial conditions in pot or sand culture, and that to-date, many -of these symptoms have not been observed under field conditions. The reported symptoms include dying-back of the uppermost branches of the tree with the lower branches showing little signs of deficiency (2); splitting and gumming of the twigs; scorching and excessive drop of leaves, resinous spotting, fading of the chlorophyll, and development of a bronze-yellow color (Haas 11-12-13-14). Tucking, and twisting of the leaf blades is still another symptom, (4). With the exception of results reported by Bryan
(2), the deficiency symptoms referred to were associated with orange varieties and not grapefruit. Whether all of these symptoms apply to grapefruit has not yet been established.
Fruit symptoms associated with potassium deficiency have also been fairly well classified, although there are some controversial reports as to the effect on the external appearance of the f ruit. Bryan (2) reported that in the few cases where fruits were produced on trees grown in pot culture, under deficiency conditions, the fruit did not appear to differ from fruit produced by trees which received potassium in sufficient amounts. Eckstine et. al. (8) have described fruit produced under potassium deficiency as being thick-skinned, coarse, and with poor color. Fruit of small size has been reported by most workers to be characteristic of fruit produced by potassium deficient trees, (1, 6, 13, 14, 19). It is generally agreed that oranges produced by trees deficient in potassium will contain a lower percentage of citric


THE EFFECT OF VARIABLE POTASH FERTILIZATION
ON THE QUALITY AND PRODUCTION OF DUNCAN GRAPEFRUIT







SITES: POTASH FERTILIZATION


acid in the juice, (17, 1, 19, 13, 14). Roy
(17) has further reported that Valencia oranges not supplied with potassium produced fruit with a higher content of reducing sugar, a lower content of non-reducing sugar, and a lower pH of the juice.
Although it was believed for many years that muriate of potash was an inferior source of potassium for the fertilization of citrus, investigations by Roy (17), Cowart (7) and Bahrt and Roy (1) have shown that either potassium sulfate or chloride are satisfactory fertilizer salts. An explanation of the background concerning these sources of potassium is necessary for it emphasizes the importance of magnesium in relation to potash fertilization practices, and to some extent the effect of magnesium on the interpretation given to some of the earlier potassium experiments. During World War I, this country was forced to depend largely on domestic sources of potassium. One of these, potassium chloride caused trouble because of the boron which it contained. Because of these experiences, combined with unsatisfactory results from using muriate on other crops, especially tobacco and potatoes, potassium chloride was held in disfavor and preference was given to sulfate as a source of potassium for citrus.
Kainite also used as a source of potassium contained appreciable amounts of magnesium as magnesium sulfate and chloride. As magnesium deficiency became more wide-spread in Florida in the late twenties and early thirties it was found that larger applications of Kainite improved the quality of f ruit . on these magnesium deficient groves. Large, coarse f ruit is associated with magnesium deficiency and when Kainite was applied to deficient trees the fruit quality improved not because of the potassium but because of the added magnesium.


The potash source experiment started in 1924 at the Citrus Experiment Station and continued until 1942, furnishes another good example of the effect of magnesium on the interpretation of results of a potassium experiment. This experiment was initiated to ascertain the effect of muriate, sulfate and sulfate of potash and magnesia on the growth and production of citrus. After several years the sulfate of potash and magnesia appeared to be a superior source of potassium. When under the direction of Dr. A. F. Camp, magnesium sulfate was added to the muriate and sulfate of potash treatments in amounts equivalent to the magnesium contained in the sulfate of potash and magnesia treatments, the differences between the plots disappeared (7).
These examples illustrate the multiplicity of factors which are frequently involved in studying fertilizers for tree crops, some of which may not even have been considered when the experiment was initiated.

Methods
The experiment discussed in this paper was first started in 1921, as reported by Ruprecht (18). At that time a block of Duncan grapefruit was laid out into six plots in such a manner that plots designated as 1, 3 and 5 received 3 percent, and plots 2, 4 and 6 received 10 percent potash in the fertilizer mixture. In the 1924 report, Ruprecht stated that the potash treatments for plot 5 were changed so that 3 percent potash was applied in the spring, 5 percent in the summer and 10 percent in the fall applications. During the period between 1924 and 1929 the plots were changed again so that plot 5 received 5 percent potash at each application and plot 6 received 3 percent potash in the spring, 5 percent in the summer and 10 percent in the fall applications. The plots were continued in this manner






















































TABLE 1.
FERTILIZER PROGRAM FOR THE PLUS MAGNESIUM PLOTS, BLOCK V. 1939-TO-DATE.

Plot No. Formula (Percentage)
N P O _ KO Mgo MnO Cuo
6 3 6 0 3 1 "/2
1 & 3 3 6 3 3 1 1/11
5 3 6 5 3 1 1/2
2 & 4 3 6 10 3 1 1/2


FLORIDA STATE HORTICULTURAL SOCIETY, 1950


until 1936, at which time the original experiment was discontinued and the plots were turned over to Dr. A. F. Camp and his co-workers at the Citrus Experiment Station.
In the 1930 report, Ruprecht (18) had stated that the trees in the plots receiving 10 percent potash were in an unsatisfactory condition. It later developed that the cause of this condition was due to deficiencies of magnesium, copper, zinc, and manganese, with magnesium deficiency being especially acute. In order to correct this condition nutritional sprays were applied, and 4000 pounds of dolomitic limestone was applied to part of this block during 1936, 1938 and 1939, with the same potash treatments as used by Ruprecht being continued.
Beginning with the fall application in 1939, plot 6 was changed to a 0 percent potash treatment and the trees in this plot have received no potash fertilizer since that time. During the period since 1936 the trees have been on a 3 percent nitrogen program, and since 1939 have received a mixture with the formulas shown in Table 1. These mixtures are applied three times a year in February, June and October. The poundage has varied somewhat through the years, having been increased as the trees became larger. Since 1939 the poundage has varied between 15 and 20 pounds per application. Zinc is applied annually as zinc sulfate at the rate of 3 pounds per 100 gals. as a


dormant spray. Except as noted, the plots all receive identical treatment in keeping with good grove management practice.
The term internal fruit quality as used in this paper refers to internal characteristics of the fruit based on soluble solids, citric acid, and ascorbic acid content of the juice. Total soluble solids were measured with a Brix hydrometer and the readings corrected to a temperature of 17.5'C. Total titratable acidity, (calculated as anhydrous citric acid) was determined by the titration of a 25 ml. aliquot juice against .3125 N sodium hydroxide solution. The ascorbic acid (vitamin C) content was determined by the method of Menaker and Guerrant (16) and reported as milligrams of ascorbic acid per 100 miffiliters of juice.

Results
Visual Deficiency Symptoms under Field Conditions-Under artificial conditions, it is possible to grow citrus trees which manifest deficiency symptoms of potassium rather rapidly. This is not true under field conditions because it is not possible to eliminate potassium from a soil as can be done with a nutrient solution. The increased period of time required f or deficiency symptoms to become evident in the field is due to several factors. The tree stores potassium, which apparently may be redistributed and reassimilated to such an extent, that the growth centers are not immediately affected. Also, a citrus tree appears to









I Another potassium deficiency symptom which has been apparent on occasions is the tendency for the trees not supplied with potash to lose young shoots during windy periods. During the early part of March, 1950, rather high winds with light rains occurred for several days shortly after the spring flush of growth
TABLE 2.
The Effect of Variable Potash Fertilization on the
Pre-harvest Drop of Duncan Grapefruit.
Percentage of Dropped
Fertilizer Fruit*
Treatment 1948-49 1949-50
N-P2Q,,-K20-MgO-MnO-CuO 3- 6 - 0 - 3 - I - 1/2 45.7 82.5
3- 6 - 3 - 3 - I - 37.3 67.2
3- 6 - 5 - 3 - 1 - 29.5 68.5
3- 6 -10 - 3 - I - 1/2 29.5 62.9
*Values represent percentage of total number of fruits. Drop counts were made from September 23 through Dec. 3, 1948, and from August 31 through Nov. 25, 1949.

had appeared. About a week later it was observed that a number of young shoots 3 to 15 inches in length had been blown f rom the trees and were lying on the ground. The number of shoots blown off in each of the potash plots is recorded in Table 3. The break always occurred at the point of emergence of the shoot from the stem or branch.
At the present time there are no distinct observable differences in tree condition between the trees which are receiving the 3, 5 and 10 percent potash applications, but there is a sharp contrast between the potash fertilized trees and those which receive no potash fertilizer. Trees in the latter plot are decreasing in size, the tops are thin and the leaf size now appears small on a number of trees. Leaf symptoms denoting potassium deficiency are not obvious. Some twisting and tucking of the leaves of a few trees have been noted on occasion.
Internal Fruit Quality. Sampling and analyses of the fruit produced by the trees in the potash plots bas been con-


SITES: POTASH FERTILIZATION


be relatively efficient in absorbing and utilizing potassium ions with which its root system comes into contact, (20). Still another factor is the reutilization of potassium resulting f rom the decomposition of dropped fruit in the grove. Where potash fertilization was withheld entirely from the trees in plot 6, beginning in 1939, no symptoms of potash deficiency developed until the spring of 1943. Following the cold period of February 15-18, 1943, it was observed that the trees in this plot suffered more cold damage than in the plots where potassium was supplied. It was also becoming evident at this time, that the trees were showing less top growth and that the leaves were smaller, but very marked differences in tree appearance were still not evident. At about the same time, it was noted that more f ruit was dropping previous to harvest where potash was withheld. This condition continued to develop and by the 1945-46 season was very evident. The trees not supplied with potash have thus far continued to bloom and set fruit, but beginning sometime in July a heavy pre-harvest drop occurs which usually continues through the harvesting season. Table 2, shows the percentage of the crop which dropped during the past two seasons. The larger number of drops listed for the 1949-50 season includes fruit which was blown f rom the trees during the August 27th hurricane. During the past three seasons the drops have been removed regularly from the grove and since starting this practice the trees appear to be declining more rapidly f rom potassium deficiency than bef ore, indicating the potassium reserve in these trees is becoming low. It should be noted that had the experiment been discontinued before the spring of 1943, say at the end of 3 years, a flat but erroneous conclusion could have been drawn that potash fertilization was unnecessary,







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


tinued regularly since 1939. A considerable amount of data relative to fruit quality has been obtained, but only data for the past three years covering soluble solids, percent citric acid, solids/acid ratio and the vitamin C content is being presented at this time. This is representative of the data as a group and shows the difference in these juice characteristics as influenced by the potash treatments which the trees have received.
Contrary to results reported by Roy
(17) and Bahrt and Roy (1) in their study of Valencia oranges, the soluble solids content of the juice of Duncan grapefruit from potassium deficient trees is significantly lower in most cases than where potassium is supplied. Variations in the rate of potash application between 3 and 10 percent in most cases caused no significant difference in the soluble solids content of the juice (Table 4). The percentage of titratable acid is consistently and very sharply reduced where potash is limiting, and is increased significantly with increasing applications of potash up to 10 percent in the fertilizer mixture (Table 4).
TABLE 3.
Loss of New Shoots as Affected by Variable Potash
Fertilization.


Fertilizer Treatment
N-PO-K.O-MgO-MnO-CuO' 3- 6 -0 - 3- 1 - 1/ 3- 6 - 3 - 3 - 1 - 'A 3- 6 -5 - 3 - 1 - VA 3- 6 -10 - 3 - 1 - 1,


Average Number of Shoots Lost Per Tree


182.8 11.3
19.3
10.7


In as much as �the ratio, (soluble solids/acid) of grapefruit juice is usually the factor determining earliness of maturity for grapefruit, the effect of potash applications on the ratio is of particular interest. The ratio of soluble solids to acid is increased where potas h is limiting, and is decreased significantly with increasing applications: of potash. The decrease in the ratio where the


a; 4 -4

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TABLE 5.
ESTIMATED DATES OF PASSING LEGAL MATURITY STANDARDS AS AFFECTED BY VARIOUS POTASH FERTILIZATION TREATMENTS.
Treatment 1948-49 1949-50
Estimated Difference Estimated Difference N-P205-K2O-MgO-MnO-CuO Date in Days Date in Days

3 - 6 - 0 - 3 - 1 - 1/2 September 10 October 15
3 - 6 - 3 - 3 - 1 - 1/2 October 2 22 December 10 56
3 - 6 - 5 - 3 - 1 - 1/2 October 15 35 January 3 80
3 - 6 - 10- 3 - 11 - 1/2 October 18 38 January 6 83


SITES: POTASH FERTILIZATION


potash application has varied between 5 and 10 percent has been significant some seasons and not in others, Table 4. In general however, the trend has been for the ratio of the juice to continue to decrease with application of potash up to 10 percent in the fertilizer mixture. The differences in the time of passing legal maturity as influenced by these fertilizer treatments for the past two seasons are presented in Table 5.
The effect of potassium deficiency and variable potash application on the vitamin C content of the juice, follows a pattern very similar to that discussed for soluble solids. Where potassium is limited, the vitamin C content of the juice is significantly decreased. Variation in the application of potash from 3 through 10 percent has resulted in slight increases in the vitamin C content at the higher applications but the differences are slight (Table 4).
External Quality.-The conclusions drawn by Eckstein, Bruno and Turrentine (8) that potash deficiency is manifested by the production of large, coarse fruit are apparently incorrect. The reports of investigators working with oranges, and a previous study by the author (19) show clearly that small f ruit, with thin rind, and good texture, are produced where potash is limited. There has been no consistent difference in the proportion of Duncan grapefruit meeting the several standard U. S. Grades, due to potassium deficiency, or to variations in


the level of potash fertilization. Early in the season there appears to be a rather large differential in size of fruit produced between trees which receive no potash fertilization and those which do. As the season progresses this is less apparent, probably due to the increased number of drops and the smaller number of fruit left on the deficient trees. During the past five years the fruit from the trees not supplied with potash has averaged about 0.10 inches smaller in diameter than fruit from trees supplied with potash. This is slightly less than the difference in average diameter between one commercial size. During the entire period the fruit from these plots has always been held late into the season, which probably accounts'for the differential in size not being greater. No consistent differences in size of fruit produced has been found to-date where potash has been applied, even though the N/K20 ratio has varied from 1-1 to 1-3.3.
Production.-Table 6, presents a summary of the production of f ruit as affected by variations in the level of potash fertilization during the period f rom 1940-41 through 1949-50. These data, based on the average production for the past nine years, show that the trees receiving 5 percent potash fertilization have yielded significantly more fruit than the trees receiving the other treatments. The difference between the production of these trees, and those to which 3 per-







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


cent potash is applied, is of greater inter- t to
est when tree condition as affected by -
previous treatment is considered. The reports of Ruprecht frequently indicated - . 0o 0
that trees receiving the 3 percent potash !" C 1 t 10
treatment were producing the most fruit during the period from 1921 until 1936, 0 C:)
with the exception of one year, 1934. M n - a .- ca
Further, Camp (3) reported that the 3 percent trees were affected the least ;
by magnesium deficiency at the time that -1 0 1 U
the original experiment was stopped, and corrected, in 1936. Based on previ- z
ous performance, the highest production L q -should be from the trees supplied with H > > 0
3 percent potash. The indications are
that 3 percent potash, which is equiva- N L 0 - ,
lent to 1:1 nitrogen-potash ratio at the
UCA
rate of application used, has not been c
sufficient to maintain production as com- 0 0 4 M
pared to the higher 1:1.6 ratio which corresponds to the 5 percent treatment. Statistically there is no significant dif- cz: c a
ference in the production of fruit from o
trees receiving the 0 percent, 3 percent or the 10 percent potash treatment as E. i
ascertained by the nine year average. It is evident from the data, however, that
-" C11 M --4 E
the production of the trees receiving no 2 t- N 0
potash has fallen off badly since the 1946-47 season, the average yield per 0 r
tree since that time being only 295 pounds. The nine year average value -
for the trees not supplied with potash is comparatively high by virtue of the fact that these trees were producing heavily > -- -during the early part of the experiment. 0
H
Discussion W, -1 1
Under the present maturity law in Florida, earliness of maturity for grape- H fruit, once the juice content require- . ments are met, is determined in most cases by the solids to acid ratio of the -0 c
juice. Reported earliness of maturity 6 o C M o
of grapefruit as affected by a low nitro- , . .
gen to potash ratio (19), together with i i , H
similar results having been reported for C'







SITES: POTASH FERTILIZATION


oranges has resulted in a more widespread use of lower nitrogen-potash ratios in fertilizer mixtures. Ruprecht reported in 1936 that based on the results of the potash rate experiment at that time that there appeared to be no advantage in using a ratio of nitrogen to potash higher than 1:1. The fact that production appears to be falling off in the plots which are receiving this treatment and that the number of drops is usually higher than in either the 5 or 10 percent plots would seem to indicate that this ratio may be too narrow to obtain maximum yields at the rate of application used in this experiment.
It should be emphasized that it has not been possible under the conditions of this experiment to see immediate effects from changes in potash f ertilization either as related to tree condition, production or fruit quality. The rather quick responses which have been evident in citrus from correcting zinc deficiency, or from applications of nitrogen have not been observed as a result of variations in the applications of potash. Thus, if the lower production which has been found in this experiment where a 1-1 nitrogen-potash ratio has been used, may be considered as indicative of what happens under field conditions generally, the production may be decreased so gradually in a commercial grove as to go unnoticed except by the most discerning growers.
The nitrogen to potash ratio in a 4-6-8-3-1-1/2 fertilizer mixture applied in the fall and summer applications, followed by an 8-0-8-6-2-1 spring topdresser, is approximately a 1-1.67 ratio of nitrogen to potash and not a 1-2 as it is frequently referred to. This corresponds to the 5 percent potash application used in this experiment which has to date resulted in the highest average yields. Even where this ratio is applied, as was pointed out earlier


by Fudge (19), a large percentage of the applied potassium is removed annually by the harvested crop. It is of course, a matter of conjecture as to the results which might have been obtained had the rates of application of these mixtures also been varied but this was not included in this experiment.

Summary
Potassium deficiency under field conditions for Duncan grapefruit was manifested by slow growth and thinning of the tops of the trees, loss of young shoots by wind, pre-harvest drop of f ru it and decreased production. The fruit produced was small in size, with good texture and thin rind. Intern-il quality was characterized by decreased soluble solids, citric acid and vitamin C content. Fruit from deficient trees matured earlier as judged by the soluble solids/citric acid ratio. The acid content of the juice increased and the ratio decreased in fruit produced by trees supplied with potash applications ranging up to 10 percent in the fertilizer mixture.
Continuous use of a 1:1 nitrogenpotash fertilizer ratio at the rate of application used in this experiment resulted in decreased yield of fruit as compared to a 1:1.67 nitrogen-potash ratio.
LITERATURE CITED
1. BAHRT, GEORGE M., AND Roy, WALLAcF R.
Progress Report of the effects of no potassium and various sources and amounts of potassium on citrus. Fla. Sta. Hort. Soc. Proc. 53: 26-38.
1940.
2. BRYAN, 0. C. Potash deficiency in grapefruit.
Identifying symptoms developed in tests. Florida
Grower. 43(l): 14-16. 1935.
3. CAMP, A. F. A resume of feeding and spraying citrus trees from a nutritional standpoint.
Fla. Sta. Hart. Soc. Proc. 56: 60-79. 1943.
4. CAMi,, A. F., CHAPMAN, IL D., BAHRT, GUORGr, M., AND PAHKFR, E. R. Hunger signs in crops.
Judd & Detwiler, Washington, D. C. 267-311.
1942.
5. CHAPMAN, H. D., BROWN, M. Analysis of orange leaves for diagnosing nutrient status with reference to potassium. Hilgardia. 19: 501-540.
1950.







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


6. CHAPMAN~, H. D., BROWN, S. M., AND RAYNER,
D. S. Some effects of potash deficiency and excess on orange tree growth, composition aod fruit quality. Calif. Citrogra ph. 33(7): 278,
279, 290. 1948.
7. COWART, F. F. Effect of source of potash upon
fruit composition. Fl a. Agr. Exp. Sta. Ann. Rept.
146-148. 1944.
8. ECKSTEIN, OSKAR, BRUNO, ALBERT, AND TUssRENTINE, J. W. Potash deficiency symptoms.
1-235. Illus. Berlin. 1937.
9. FUDoE, B. R. AND FERMIERLING, G. B. Some effects
of soils and fertilizers on fruit composition. Fla.
Sta. Hart. Soc. Proc. 53: 38-46. 1940.
10. Fudge, B. R. Fla. Agr. Exp. Sta. Ann. Rept.
150-152. 1946.
11. HAAS, A. R. C. The growth of citrus in relation to potassium. Calif. Citrograph. 22 ( 1 & 2)
6, 17, 54, 62. 1936.
12. -.---------- Potassium in citrus leaves and
fruits. Calif. Cit rograph. 22: 154-156. 1937. 13. -.--------- Effect of potassium on citrus
trees. Calif. Citrograph. 33(11): 468, 486,
487, 488, 490. 1948.


14. -.--------- Potassium in citrus trees. Plant
Physiology. 24: 395-415. 1949.
15. KimE, C. D., JR. Leaching of potash from
sandy citrus soils of Florida. Fla. Sfa. Hart.
Soc. Proc. 56: 43-48. 1943.
16. MENAKER, M. H., AND GUERRANT, N. B. Standardization of 2-6 Dichlorophenolindophenol an improved method for determination of vitamin C. lour. Ind, and Eng. Chem. (Anal.) 10: (1)
25, (5) 269. 1938.
17. Roy, W. R. Effect of potassium deficiency and
of potassium derived from different sources on the composition of Valencia oranges. lour. Agr.
Res. 70(5): 143-169. 1945.
18. RUPRECHT, R. W. Effect of potash on conmposition, yield and quality of the crop. Fla. Agr.
Exp. Sfa. Ann. Repts. 1922-1936.
19. SITES, JOHN W. Internal Fruit Quality as related to production practices. Fla. Sta. Hart.
Soc. Proc. 60: 55-62. 1947.
21). WANDER, I. W. (Unpublished Data). Citrus
Experiment State, Lake Alfred, Fla.


PANEL ON PARATHION


HOWARD A. THULLBERY
Lake Wales
Mr. President, Members of the Florida
Horticultural Society and Guests:
The Executive Committee of the Society requested that a panel be developed on Parathion to be presented at this meeting.
In planning the panel the assistance of Dr. J. T. Griffiths, Mr. W. L. Thompson and Mr. Frank L. Holland was sought.
Due to the keen intellect and efforts of these three gentlemen, plus the very fine cooperation of the twenty-two gentlemen seated before you, we have the panel prepared according to the outline that has been distributed to you.
These gentlemen, no doubt, are among the best qualified to speak on Parathion and its uses that could be found in the world today. They each have prepared questions which they are qualified to discuss intelligently. Many have prepared questions, they want others in other fields of work to answer. The opportunity has been given all of you to submit questions and many of you have done so.


All of these questions have been sorted and grouped and will be answered by the person or persons qualified in that particular field.
Whether or not the 'Moderator will allow questions from the floor will depend entirely on time. The outline covers all phases of the subject and we feel that all phases should be covered rather than too much time he spent on certain phases and others neglected.
While Parathion is undoubtedly an outstanding insecticide, it like all material, has its limitations. It is expected that the discussions here today will deal with the limitations as well as the outstanding qualities of this material.
On behalf of the Society and personally, I wish to thank each of you gentlemen who have helped plan the panel and all of you who are participating in it.
I now turn the panel over to our most efficient Moderator, Mr. Frank Holland.
Moderator: We will go right to work if members of the panel are ready. Before we get into detailed questions there is a preliminary question which the mod-







THULLBERY: PANEL ON PARATHION


erator will direct to Dr. Bruce D. Gleissner, Entomologist with the American Cyanamid Company.
What is Parathion?
Dr. Gleissner: Well, Mr. Holland, Parathion is an organic phosphate. Actually the name Parathion is the common name for the chemical 0, O-diethyl-O-. paranitro-phenyl-thiophosphate. Obviously, you couldn't use such a long chemical name so they picked Parathion. The compound was discovered in Germany but it has been more widely developed here in the United States for the control of several hundred economic species of insects and mites that attack crops grown in this country.
Moderator: Thank you Dr. Gliessner. Now, to Dr. Herbert Spencer, Entomologist with the United States Department of Agriculture's Subtropical Fruit Insects Laboratory at Fort Pierce. I .In the USDA experiments, what citrus pests have been controlled with Parathion?
Dr. Spencer: The purple scale, Florida red scale, cloudywinged aind citrus white flies and some of the mealybugs. The insects and mites that have not been controlled well are the purple mite and the rust mite.
Moderator: What materials have you found compatible with Parathion?
Dr. Spencer: We have found Parathion compatible with wettable sulfur, with coppers and with oil; in fact, with most of the insecticides and fungicides except those that are very basic. We have not used it with liquid lime sulfur but there is a possibility it can be used in that combination too.
Moderator: What poundage per 100 gallons of spray gives adequate control of scale insects?
Dr. Spencer: In our cleanup work for heavy infestations we are using 2 pounds of 15% wettable with wettable sulfur. There is a possibility with light infesta-


tions that two applications spaced over the year with 1 pound of 15%7 each time may keep the infestations to, a very low level.
Moderator: Thank you Dr. Spencer. The next questions will be directed to Mr. W. L. Thompson, Entomologist with the Citrus Experiment Station at Lake Alf red.
To obtain scale control, is it necessary to spray trees as thoroughly with Parathion as it is with an oil emulsion?
Mr. Thom)pson: Yes. Although Parathion has some fumigating effect it has not the same effect that you would expect from sulfur for rust mite control. Purple scale control was not satisfactory where a combination spray containing Parathion, copper and sulfur was applied as an outside brushing spray which was typical of the usual application made for melanose and rust mite control. The scales should be covered with Parathion for satisfactory control.
Moderator: Is Parathion as effective as oil emulsions for purple and red scale control ?
Mr. Thompson: On a three year average it has been as effective as oil emulsions. However, this year where we have had an abundance of red scale, there are more red scale in the tops of the trees where we sprayed with Parathion than we have with oil emulsions. On the average, it has been as satisfactory as oil emulsions.
Moderator: Are two applications of Parathion at 1 to 100 as effective as one application at 2 to 100?
Mr. Thompson: If there is a light to medium infestation of scale to start with, two applications of 1 pound of 15%( material have been as satisfactory as 2 pounds per 100 put on once. In other words, a Spring application with another application in July or August, both with 1 pound to the 100, have been just as satisfactory and in some cases







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


more so than when the application was delayed until July or August with 2 pounds to the 100 used.
Moderator: Does purple mite infestation develop faster following a Parathion spray than where no Parathion was applied?
Mr. Thompson: There is very little evidence to show that the effect of Parathion increases purple mite. Parathion does not kill eggs, only the active mites; therefore, when you have a rather heavy infestation of purple mites when you apply the Parathion spray, you can expect a comparable infestation about two to three weeks later. Two Parathion sprays applied at ten day intervals would probably control purple mites but that is really not practical.
Moderator: Thank you Mr. Thompson. The next questions will be directed to Dr. R. K. Voorhees, Associate Horticulturist with the Citrus Experiment Station at Fort Pierce.
What are some of the factors responsible for certain casesof poor or inconsistent citrus scale control with Parathion during 1950?
Dr. Voorhees: Some of the factors responsible for poor scale control with Parathion, as far as the East Coast is concerned, are: poor tree coverage for any reason, but frequently due to windy weather which also shortens the period of effectiveness of Parathion; thorough tree coverage for good scale control is frequently not obtained with the broomtype hand spray guns and- the boomtype applicators -employed on the coast; low or minimum concentrations on heavy scale infestations during any season.
Moderator: How effective is Parathion in reducing scale infestations when employed at a minimum rate in combination with the spring melanose sprays?
Dr. Voorhees: In general, good results have been obtained with Parathion


when combined with the melanose sprays at the minimum rate of 1 to 11/2 pounds per 100 gallons. In most cases, this has reduced light to medium infestations to the extent that only a minimum dosage had to be considered during the summer, and in some cases this second application was not needed until fall.
Moderator: What are some of the main factors responsible for accidents that occurred in connection with the use of Parathion by citrus spray operators on the East Coast during 1950?
Dr. Voorhees: In checking on several authentic cases of Parathion poisoning to citrus spray operators there were several different factors responsible, but no single factor particularly predominate. Some of these factors were: negligence in following the recommended precautions; abnormally low cholinesterase level of the operator; overexposure from spraying in windy weather, high summer temperatures and especially in connection with heavy canopied groves with poor air circulation, and from being exposed to Parathion too many days at any one interval.
Moderator: Thank you Dr. Voorhees. The next set of questions will relate to vegetable crops, so as to continue under Item I of the agenda, and will be directed to Mr. Norman C. Hayslip, Associate Entomologist with the Everglades Experiment Station at Fort Pierce.
Does Parathion have a place in controlling sweet corn insects?
Mr. Hayslip: The use of Parathion on sweet corn is still in-the experimental stage; however, we have conducted a series of studies using Parathion on sweet corn. It has shown up better than any other material f or the control of the corn silk fly, killing the adult stage just before the silks appear, thus preventing opposition. On corn earworm, Parathion at 2 /- strength in a dust was, in two experiments, slightly superior to 5%







THULLBERY: PANEL ON PARATHION


DDT dust; at 1 % it was slightly inferior to 5% DDT dust. Cage trials indicated that Parathion has some toxic effect on adult moths of the corn earworm. The effect on the adults has not been verified under field conditions, however. Against fall armyworms, Parathion is effective at higher rates of application. That is to say, 2 pounds of 15% wettable to 100 gallons of water. Parathion also reduces the damage caused by aphids on corn.
Moderator: In most cases, it has not been recommended to use Parathion on vegetables later than 30 days before harvest. How does this restriction affect the use of Parathion on vegetables?
Mr. Hayslip: This question was phrased to show that such a restriction is impractical on some crops. One example would be tomatoes, which are harvested over a period of 40 to 50 days; by adding 30 days to the first harvest, results in a period of 70 to 80 days that the tomato plants are in the field unprotected by this insecticide, leaving them exposed for a long period of time to attack by insects. Other crops of a similar nature would be peppers and, to some extent, cucumbers. The question points out the very serious need for more intelligent recommendations as to the period of time elapsing between the last treatment and harvest; and I am happy to say that I have just recently learned we are getting more and more information on the subject. I was told recently that 21 days is now the period for most vegetable crops and, even more recently, that some have even a smaller lapse of time between harvest and the last application.
Moderator: Thank you Mr. Hayslip. I believe that later on in the panel there will be some further information developed on that one point. The next questions will be directed to Dr.'E. G. Kelsheimer, Entomologist with the Vegetable Crops Laboratory at Bradenton.
Is Parathion compatible with fungi-


cides and nutrients used in vegetable sprays?
Dr. Keisheimer: Parathion is compatible with our dithicarbamates and copper sprays commonly used on vegetables. There is one exception; you should not use lime in combination with the carbamate f ungicides. It is compatible with practically all our insecticides; again, one exception, which is cryolite. A common practice with us is to add nutrients to the combination of insecticidal and fungicidal sprays but we have evidence to show that an excess of zinc and iron, and naturally lime, has an adverse effect on Parathion.
Moderator: What is the best time of day to apply Parathion on vegetables?
Dr. Keisheirner: We find that the best time to apply Parathion is the latter part of the day and especially after the dew is off the plants. We have found that Parathion will cause burn on tomatoes and cucurbits, such as squash and cucumber, when the foliage is wet. IModerator: Thank you Dr. Kelsheimer. The next questions will be directed to Dr. J. W. Wilson, Entomologist at the Central Florida Experiment Station, Sanford.
Does Parathion kill insects by fumigation or is it necessary for the Parathion to come in contact with the insects to be effective?
Dr. Wilson: Parathion is capable of killing insects by acting as a fumigant, a contact poison or as a stomach poison. Thus it is not necessary for Parathion to come into contact with the individual insects to kill them. But the greatest benefit from Parathion is obtained when it is applied to thoroughly cover the entire leaf surfaces and particularly the lower surface where most insects are found.
Moderator: Why is Parathion so often recommended for use on vegetable crops in preference to nicotine sulfate?







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Dr. Wilson: That question, I think, refers to the weather conditions under which vegetable crops are grown in Florida. Nicotine sulfate requires temperatures of 800 F. and should be applied when there is little or no air movement to be most effective. We seldom have weather conditions favorable for the most effective use of nicotine sulfate. Parathion is more effective than nicotine sulfate under our weather conditions.
Moderator: What information is
available on the residues which may be found on vegetables following the use of Parathion?
Dr. Wilson: The residue data available for Parathion on Florida grown vegetables are rather meager but the information we have in conjunction with information from other sections of the country indicates that Parathion deteriorates rather rapidly. After from two to four days very little Parathion remains on the vegetable and after a period of twelve to fifteen days only traces of Parathion can be found.
Moderator: Thank you Dr. Wilson.
The next questions will be directed to Dr. D. 0. Wolfenbarger, Entomologist at the Sub-Tropical Experiment Station, Homestead.
Is Parathion satisfactory for control of soil inhabiting insects?
Dr. Wolfenbarger: Mr. Thames of the Everglades Experiment Station is finding it is very satisfactory for use on the muck soils there for the control of wireworms. In Perrine marl soils of Dade county it is a little different story there, and Parathion has not been effective in wireworm control on our potato growing soils.
Moderator: Are any precautions advisable for use of Parathion on leafy crop plants?
Dr. Wolfenbarger: Yes, that is one place where we need a great deal of precaution. One of the places of question-


able use of Parathion is on our leafy vegetables and on our fruits that we eat. Potatoes, on the other hand, is an example of a crop where we don't need to worry about the residue problem.
Moderator: How frequently need Parathion applications be made for pest control on vegetable crops?
Dr. Wolfenbarger: The answer to that question, I am afraid, is very variable and it will depend to the greatest extent on your insect infestations. If you have a very heavy one, you may have to put it on every five to seven days or so to combat that infestation. On the other hand, if your infestation is fairly light, or incipient, one or two applications may be satisfactory to control the pests in that case.
Moderator: Thank you Dr. Wolfenbarger. The next questions will be directed to Dr. Herbert Spencer, Entomologist with the U. S. Department of Agriculture Sub-Tropical Fruit Insects Laboratory at Fort Pierce. Dr. Spencer, these two questions deal with subtropical f ruits.
What pineapple pests have been controlled with Parathion?
Dr. Spencer: The pineapple mealy bug is the main one, and there is some evidence that the red spider of pineapple may be partially controlled with it.
Moderator: How does Parathion compare with DDT for control of little fire ants ?
Dr. Spencer: The little fire ants on subtropical fruits and on citrus can be controlled by the applications of Parathion used for scale control, for a period of about four months. DDT gives a longer period of protection. You get about eight months protection from DDT on the trunks of the trees, whereas you get about four months protection against the fire ants from the Parathion spray applied with complete coverage.
Moderator: Thank you Dr. Spencer.







THULLBERY: PANEL ON PARATHION


Continuing with the subtropical f ruits, Dr. Wolfenbarger.
On what subtropical fruits may Parathion we used? For what pests?
Dr. Wolf enbarger: It seems that Parathion has a very wide use on many of our subtropical plants, beginning with the avocado. It has been used on the avocado for dictospermum scale, in which case it seems it compares very favorably with oil emulsion for control of the scale and then, in addition, there is not the danger of plant injury. It gets the red banded thrips on avocados. It gets the leafrollers and is very effective for many places, it seems, for avocados. It has been used on limes, for example, in which case it is equivalent to oil and, in addition, there is not the chance for plant injury there. It has been used on mangos for lesser snow scale and other scales on mangos. It would seem to me that it would have a very widespread use on the mango for all of its scale pests, and for the red banded thrips. It is very effective in those cases. There is one precaution, when you use Parathion on mangos or avocados in the season when you can expect mite infestations, and that is you had better put in your sulfur with the Parathion to combat and control the mite and spider populations. If you don't, they will build up on the subtropicals, as Mr. Thompson mentioned for citrus.
Moderator: What dosages are recommended for use on subtropical fruits?
Dr. Wolfenbarger: About one pound, the same as is generally used for other plant pests.
Moderator: The next questions will be on ornamentals and directed to Dr. L. C. Kuitert, Entomologist at the Agricultural Experiment Station, Gainesville.
What is the present status regarding the effectiveness of Parathion sprays in controlling insect infestations on ornamentals?


Dr. Kititert: Parathion appears to be somewhat superior to oil emulsions. It has the advantage that it can be applied at seasons of the year when you can't apply oil emulsions. It will control as effectively and, in some cases, more effectively most of the insect pests of our choice ornamentals.
Moderator: In your opinion, can the home gardener use Parathion safely?
Dr. Kuitert: Yes, I feel they can if they follow a few simple precautions. I don't think that a mask will be necessary if they are very careful in mixing their insecticides. Most of the home gardeners would only apply the material to perhaps six or eight ornamentals at a time. The short length of exposure and the infrequency of the application would, in my opinion, be safe for the home gardener.
Moderator: Thank you Dr. Kuitert. The next questions are directed to Mr. R. P. Tomasello of the Wilson Spraying and Supply Co., Inc. at West Palm Beach, Florida.
Has Parathion caused any spray injury to ornamentals?
Mr. Tomasello: Parathion has caused some injury to Hibiscus, Oleanders, Aralias and Bougainvilleas. There is a shedding of the older leaves when Parathion has been used at the rate of 1/-pounds of 15%c wettable Parathion to 100 gallons of water. This is especially noticeable when spraying has followed high winds or if plants suffer from a lack of adequate moisture or food. Certain varieties of the above named ornamentals appear to be more susceptible to injury than others.
Moderator: Has any illness been reported by home owners following the use of Parathion on foundation plantings, etc ?
Mr. Tomasello: Because we are aware of the potential dangers of Parathion, a careful check has been made of the homes where this material has been used. We







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


have been using Parathion approximately two years and during this time there has not been a single report by home-owners of illness following its use on foundation plantings.
Moderator: That completes Part I of our questions. We will now proceed to Part II, dealing with practical considerations for growers in field use. The next questions will be directed to Mr. Wilbur Charles, Production Manager of the Florence Citrus Growers Association of Florence Villa.
What precautions should be used to protect the user of Parathion from danger?
Mr. Charles: We have equipped our men with coveralls and masks. We have not adopted the use of rubber gloves.
Moderator: How do the growers living in groves feel about using Parathion near their homes?
Mr. Charles: We have several growers of the association living in their groves. When we started using Parathion each of these were consulted as to whether we were to use this material around their houses or not. In each case, the grower consented, in fact, he now asks us to use it around the house the same as any other insecticide.
Moderator: What changes in the groves have been observed, if any, from the use of Parathion as compared to oil?
Mr. Charles: The outstanding effect that I think I see from the use of Parathion is in the older groves, such as we have in this section. The older groves that have been here since the early 1900s, I feel, were beginning to show a great toxicity to the use of oils. Since we have been using the Parathion, I see a great improvement in the condition of the groves. This I know is not due to any change in fertilizer because the fertilizer program has been the same. We, of course, have had dry weather to com-


bat but, even with that, the groves are in better physical condition.
Moderator: Thank you Mr. Charles. We will next hear f rom Mr. Willard D. Miller, chairman of the research committee of the Florida Fruit and Vegetable Association at Ruskin, Florida.
What eff ect has sunshine and rain on removing any objectionable residue from Parathion?
Mr. Miller: That is a question, Mr. Moderator, that I have asked someone else to answer f or me. I want to hear from somebody who is qualified to answer it.
Moderator: We will be glad to direct it to some other member of the panel.
Mr. Miller: If you please.
Moderator: Alright. The next question here may also fall into that category. You be frank and say so if it does.
How close to picking time can Parathion be used on the following vegetables without danger of having excess residue which may be questioned by the Pure Food and Drug Administration? Now there are four or five vegetable crops listed. The moderator would be inclined to guess you would want that question to lay over to Dr. Gleissner who is going to discuss the answer to questions on the status of Food and Drug bearing.
Mr. Miller: Yes, you asked me to be f rank; that was another one that I wanted somebody else to answer for me.
Moderator: Thank you Mr. Miller. Now, while we are on this subject, I want to ask Dr. Gleissner a question on this very interesting subject.
Have the manufacturers of Parathion recommended any certain amount of residue that they feel can remain on a vegetable without injury to the consumer?
Dr. Gleissner: Yes sir. Both the manufacturers of Parathion and representatives of the Food and Drug Administration presented data at the Food and







THULLBERY: PANEL ON PARATHION


Drug Administration hearings to. the effect that a residual level somewhere between two and five parts per million would not be hazardous to consumers. The American Cyanamid Company placed data in the record which indicated that even a considerably greater residual tolerance could be allowed and still be conservative but under the conditions of the uses of Parathion, two to five parts is the largest that will ever be necessary.
Moderator: Thank you. I wonder if I might ask another one of these questions to Dr.'Kelsheimer or Dr. Wolfenbarger.
What effect has sunshine and rain on removing any objectionable residue of Parathion?
Dr. Kelshei))ier: What meager records we have show that Parathion is broken down very quickly under our sunlight conditions. Do you want the rainfall?
Moderator: Yes.
Dr. Kelsheimer: The rainfall also tends to wash off this residue.
Moderator: Thank you. I see there is another question, Dr. Kelsheimer, which has been answered in part. The question is as follows:
How close to picking time can Parathion be used on the following vegetables without danger of having excess residue which may be questioned by the Pure Food and Drug Administration? The commodities are tomatoes, cucumbers, peppers and leaf crops such as cabbage and lettuce. Do you think that has been answered or do you care to comment?
Dr. Kelsheimer: I believe that has been answered.
Moderator: Thank you. The next questions will be directed to Mr. J. J. Taylor of the State Department of Agriculture from Tallahassee, Florida, on State Label, Package and Control data.
Are there adequate methods for determining Parathion?
Mr. Taylor: Yes. There gre ;i num,


ber of methods for determining Parathion. The method we use in our laboratory is the colorimetric method, which was developed by Averill and Morris for residues of Parathion modified to use for dust formulations. There are a number of other methods in use but we have found this to be the most satisfactory and that is the one we use for regulatory purposes.
Moderator: Have you found accurate methods for both concentrate and dilute mixtures?
Mr. Taylor: Yes. The method is accurate both for concentrate and dilute mixtures. It is, of course, more accurate in the smaller amounts; possibly accurate in the 15 and 25 percent concentrates to something like a one-half or one quarter of 17c.
Moderator: Do you find that Parathion mixtures usually come up to their guarantee?
Mr. Taylor: For the most part Parathion mixtures meet their guarantees. A f ew have failed to do so. We found most of the companies put up their 15 and 25 percent concentrate in tin containers. For 1 percent dust, some companies use paper bags with inner linings; some, containers with tin top and bottom and cardboard sides. These seem very satisfactory but even some of the paper bags with inner linings don't seem to hold the dust in too well.
Moderator: Thank you Mr. Taylor. We will now have Section III, Citrus Fruit Quality Factors. The questions are directed to Dr. Paul L. Harding, Fruit and Vegetable Handling, Transportation and Storage Investigations, U. S. Department of Agriculture, Orlando, Florida.
Is Parathion spray superior to oil in increasing the total solids content whether applied in either June or August, or at both times?
Dr. Rarding: A fewt years ago the







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


Bureau of Entomology and Plant Quarantine and the Bureau of Plant Industry, both of the U. S. Department of Agriculture, set up experiments to determine the effect of oil and Parathion sprays on the composition of oranges. During the first two years the work was on Valencia oranges. Emphasis during the last two years has been on early oranges with the tests being made on the varieties Parson Brown and Hamlin. The results of these studies show: A. That Parathion is definately superior to oil in increasing the total solids content whether applied in June or August or at both times. B. That oil applied in June does not seem to have a depressing effect on total solids content. C. That oil applied in August has a very depressing effect on total solids.
Moderator: Did your studies show that Parathion increased the total solids content over the controls?
Dr. Harding: The question is asked, "Did Parathion definitely stimulate or give a definite increase in total solids over the control?" When we compare Parathion applied in June and August with the controls we find that there is a difference of .23 which tells us there is a significant difference between the control and Parathion applied in June and August. We can similarly establish the fact that oil sprays depress the total solids level by comparing the treatment of oil applied in August, or the treatment of oil applied in June and August, with the control. To summarize our findings, our results show that single applications of Parathion applied in June or in August did not significantly affect the total solids content when compared with the controls. On the other hand, two applications of Parathion, one applied in June and the other in August, did significantly increase total solids.
Moderator: What is the general effect of oil and Parathion sprays on Vita-


min C, total acid, and the degreening of fruit?
Dr. Harding: The ascorbic acid (Vitamin C), and the total acid content of the fruit was slightly depressed by the application of oil sprays. The differences were small and the decrease generally resulted from the applications of oil in August. Parathion sprays had very little effect on Vitamin C and the results indicate a very slight increase when our data are compared with the control fruit. The results are of interest from a scientific point of view but it should be pointed out that the increase is too small to be of practical value. The effect that various sprays have on the degreening of fruit or on the color of the rind is of importance to the citrus grower and shipper. It was, therefore, of considerable interest to find that the fruit which we sprayed with Parathion should degree at an earlier date than the fruit from either the oil or controlled plots. The brighter color of the fruit from the Parathion plots appeared to persist into the stage of over-ripeness, however the differences among treatments are not so*marked when the fruit is completely degreened. Our results show that the late oil sprays applied in August are largely responsible for the depressive effect in total solids, total acid and Vitamin C, as well as the failure of the fruit to degree as early as when sprayed with Parathion. I wish to emphasize that the early (June) applications of oil had very little deleterious effect on fruit composition or on the rind color of the fruit.
Moderator: Thank you Dr. Harding. Dr. J. W. Sites, Horticulturist with the Citrus Experiment Station, Lake Alfred, Florida, the next set of questions will be directed to you.
Have appreciable differences in the soluble solids content of the juice of fruit from trees sprayed with Parathion as







THULLBERY: PANEL ON PARATHION


contrasted to trees sprayed with oil at the same time, been found?
Dr. Sites: Yes. Very appreciable differences have been found. Of course, the magnitude of these differences depends on the time of the application of the oil spray. Where we checked groves throughout the state last year, for example, the differences, where we were comparing Parathion sprays to oil sprays applied about the middle of June varied between three-tenths Brix unit and one Brix unit.
Moderator: Does the rate of application of Parathion affect the soluble solids content of the fruit?
Dr. Sites: The work which we have done thus far indicates that the rate of application has practically no effect on the soluble solids content of citrus.
Moderator: Is the use of Parathion in place of oil sprays for scale control equally effective for all varieties in so far as the quality of the fruit produced is concerned?
Dr. Sites: So long as one is comparing Parathion against oil sprays it would have to be stated that you, cannot expect the same effect for the use of Parathion for all varieties. The reason for this is not that the Parathion is less effective on certain varieties, but rather that oil sprays do not cause the same effect consistently for all varieties. Because oil sprays usually do not cause as severe lowering of the soluble solids content in grapefruit as in oranges, it follows that one could not expect as much increase in the soluble solids content of grapefruit varieties where Parathion was used in place of oil sprays.
Moderator: Is there any reason to believe that the use of Parathion sprays will result in the production of fruit with a higher soluble solids content than would have been produced had no sprays for scale control been applied?
Dr, Sites: That question goes back


to the fact it was more or less intimated early in the use of Parathion that benefits were being gained by its use over and above the limitations set by the generic pattern of the tree itself. I do not believe that is true.
Moderator: Thank you Dr. Sites. Part IV is Processed Citrus Products Factors. The field of Molasses and Feed will be addressed to Mr. R. N. Hendrickson, Assistant Chemist at the Citrus Experiment Station, Lake Alfred, Florida.
Has Parathion been found in citrus pulp or citrus molasses and, if so, in what quantity?
Mr. Hendrickson: Citrus pulp and molasses made from grapefruit peel sprayed with 25/100 pounds active Parathion per 100 gallons was found to have approximately one part per million in the dried feed and one-half parts per million in the molasses. The Parathion content of the wet peel in this instance was considered to be an average value.
Moderator: Is the quantity of Paration present in feed and molasses barmf ul to dairy or beef cattle?
Mr. Hendrickson: Feeding trials at the Kansas Agricultural Experiment Station where dairy cattle were fed five parts per million on a total f eed basis for 81 days and thereafter slowly increased to 40 parts per million, showed the Parathion as having no harmful effect on the health of the cow. No Parathion was found in the milk, nor any objectionable off flavors. Cooperative studies between the University of Illinois, a large packing company and the American Cyanamid Company, in which beef animals consumed five parts per million actual Parathion, based on the silage intake of their diet for 100 days finishing period, showed no Parathion in the fat, lean meat, or liver tissue at the time of slaughter.
Moderator: Thank you Mr. Hendrickson. The next questions on peel oil will







FLORIDA STATE HORTICULTURAL SOCIETY, 1950


be addressed to Mr. J. W. Kesterson, Associate Chemist at the Citrus Experiment Station, Lake Alfred, Florida.
Where is Parathion found in the citrus fruit and in what concentrations?
Mr. Kesterson: The oil cells are the only part of the fruit in which the Parathion is retained. In 23 samples of coldpressed oil studied this year, for both orange and grapefruit the concentration of Parathion was found to range from 0 to 236 parts per million. In 75 percent of the samples, the range was 0 to 60 parts per million.
Moderator: Does the presence of Parathion in a coldpressed citrus oil harm the oil?
Mr. Kesterson: No. The presence of Parathion - did not show any noticeable influence on the physical or chemical characteristics of the oil. Warburg respirometer studies to determine the keeping quality or oxidative stability of the oil showed, Parathion to have.,the beneficial effect of slightly increasing the stability of the oil.
Moderator: Thank you Mr. Kesterson. The next questions relate to Residues in Citrus Products and will be addressed to Mr. C. R. Stearns, Jr., Associate Chemist at the Citrus Experiment Station, Lake Alfred, Florida.
Does the Parathion penetrate through the peel and contaminate the juice portion of the fruit?
Mr. Stearns: No. In reemphasizing Mr. Kesterson's statement, the Parathion does not penetrate through the peel of the fruit.
Moderator: If Parathion is present in the peel, will the juice expressed by different commercial extractors be contaminated with Parathion?
Mr. Stearns: In some cases we have found very small amounts of Parathion; however, these values present no health hazard and therefore are of no conseqUence.


Moderator: Thank you Mr. Stearns. The next questions, related to Canned Citrus Products, are addressed to Mr. R. W. Olsen, Biochemist at the Citrus Experiment Station, Lake Alfred, Florida.
Does Parathion sprayed on groves have any effect on flavor or keeping quality of canned citrus?
Mr. Olsen: We found no difference in flavor between the Parathion sprayed fruit and the control in freshly extracted juice or, upon storage, of the finished product.
Moderator: What happens to the Parathion, if any is present, during processing?
Mr. Olsen: Orange juice containing Parathion lost up to 48 percent of the Parathion during the processing of single strength orange juice and up to about 25 percent in the manufacture of frozen concentrate.
Moderator: Thank you, Mr. Olsen. Part V on the program relates to Human Health Aspects with Reference to Factory and Field Workers: Safety Precautions; Preventive Measures: Practical and Professional Steps that have Been Developed and Are Important to Employer and Employees; Residues; Air Contamination; Public Health and Industrial Commission Considerations. The first questions will be directed to Dr. John W. Williams, Pathologist at Morrell Memorial Hospital, Lakeland, Florida, relating to indications of susceptibility, coupled with symptoms and treatment.
Should individuals about to work with Parathion be given medical examination? If so, why? And are there any specific examinations indicated?
Dr. Williams: The answer is yes. Individuals about to work with Parathion should be given medical examinations. It is important to determine whether the individual is a psychoneurotic or not. If the grower employs a psychoneurotic, he




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PROCEEDINGS ojr-the . . " .. FLORIDA STATE : ,:. .. : i HORTICULTURAL .. . soClETY for . , 1950

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ROBINSONS ORLANDO APOPKA TALLAHASSEE

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PROCEEDINGS of the of the FLORIDA ST ATE HORTICULTURAL SOCIETY held at WINTER HA VEN, FLORIDA October 31, November 1 and 2 1950 Published by The Society

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IV FLORIDA STATE HORTICULTURAL SOCIETY, 1950 FLORIDA STATE HORTICULTURAL SOCIETY l'HESIDENT LEO H. WILSON Bradenton CITRUS SECTION KINGSWOOD SPROTT Vice-President KROME MEMORIAL INSTITUTE COL. w. R. GROVE Vice-President Lake Wales Laurel VEGETABLE SECTION DR. A. H. EDDINS Vice-President ORNAMENTAL SECTION ERDMAN \VEST Vice-President Hastings PROCESSING SECTION DR. F. w. WENZEL Vice-President Lake Alfred SECRETARY DR. ERNEST L. SPENCER, Bradenton EDITING SECRETARY W. L. TAIT, winter Haven TREASURER LEM P . . WooDs, Tampa ASSISTANT SECRETARIES DR. F. S. JAMISON, Gainesville RALPH P. THOMPSON, Winter Haven BERT LIVINGSTON, Tampa EXECUTIVE COMMITTEE Gainesville DR. J. R. BECKENBACH, Chairman, Bradenton R. S. EDSALL, Vero Beach GEORGE H. CooPER, Princeton E. V. FAIRCLOTH, West Palm Beach DR. F. E. GARDNER, Orlando FRANK L. Hou.AND, Winter Haven H. A. THULLBERY, Lake Wales

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FLORIDA STATE HORTICULTURAL SOCIETY, 19,50 FLORIDA ST ATE HORTICULTURAL SOCIETY PRESIDENT G . DEXTER SLOAN Tampa CITRUS SECTION \V1LLIAI\[ W. LAWLESS Vice-President \Vinter Haven KROME MEMORIAL INSTITUTE MARGAHET J. MUSTARD Vice-President Coral Gables VEGETABLE SECTION \V . U. Moui-.TS Vice-President ORNAMENTAL SECTION EDWIN A. MENNINGEH Vice-President West Palm Beach PROCESSING SECTION THEODORE J. KEW Vice-President \Vinter Haven SECRETARY DR. EnNEST L. SPENCER, Bradenton EDITING SECRETARY \V. L. TAIT, \Vinter Haven TREASURER LE11r P. WooDs, Tampa ASSIST ANT SECRET ARIES Dn. F. S. JAMISON, Gainesville RALPH P. THOMPSON, \Vinter Haven EXECUTIVE COMMITTEE Stuart KINGSWOOD SPHOTT, Chairman, Lake \Vales FRANK L. HOLLAND, \Vinter Haven R. S. EDSALL, Vero Beach DR. RALPH L. MILLER, Plymouth E. V. FAIHCLOTH, \Vest Palm Beach WILLARD D. MILLEH, Ruskin H. A. THULLBERY, Lake \Vales V

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FLOIUDA STATE HOHTICULTUHAL SOCIETY, 19,50 VII CONSTITUTION Article 1. This organization shall be known as the Florida State Horticultural Society, and its object shall be the ad vancement of Horticulture. Article 2. Any person or firm may become an annual member of the Society by subscribing to the Constitution and paying four dollars. Any person or firm may become a perennial member of the Society by subscribing to the, Con stitution and paying the annual dues for five or more years in advance. Any per son or firm may become an annual sus staining member of the Society by sub scribing to the Constitution and paying ten dollars. Any person may become a life member of the Society by subscribing to the Constitution and paying one hun dred dollars. Any person or firm may become a patron of the Society by sub scribing to the Constitution and paying one hundred dollars. Article 3. Its officers shall consist of a President, one Vice President for each section, Secretary, Treasurer, Assistant Secretaries, and Executive Committee of seven', who shall be elected by ballot at each annual meeting. These officers shall take their positions immediately following their election. The duties of the Assistant Secretaries shall be out lined and supervised by the Executive Committee. Article 4. The regular annual meet ing of this Society shall be held on the second Tuesday in April, except when ordered by the Executive Committee. Article 5. The duties of the Presi dent, Vice Presidents, Secretary and Treasurer shall be such as usually de volve on these officers. The President, Secretary and Treasurer shall be ex officio members of the Executive Com mittee. Article 6. The Executive Committee shall have authority to act for the Society between annual meetings. Article 7. The Constitution may be amended by a vote of two-thirds of the members present. Article 8. A section of the annual pro gram of the Society shall be devoted to the discussion of sub-tropical fruits, ex clusive of the commonly grown varieties of citrus fruits. This section shall be known as the Krome 1tfemorial Institute. It shall be presided over by a fourth vice president who shall be elected by ballot at each annual meeting of the members in attendance at the Institute. The fourth vice president shall be an ex-officio mem ber of the Executive Committee. Article 9. The Executive Committee may, at its discretion and on the basis of merit, nominate not to exceed five per sons in any one year, for Honorary Mem bership in the Society. Honorary mem bers shall enjoy all privileges of the Society. Article 10. A section of the annual program of the Society shall be devoted to the discussion of vegetables and other truck crops. This section shall be known as the Vegetable Section of the Florida State Horticultuml Societ11. It shall be presided over by a Vice President, who shall be elected at each annual' meeting of the Society by the members in attend ance at the Session. The Vice President shall be an ex-officio member of the Executive Committee. Article 11. A section of the annual program of the Society shall be devoted to the discussion of ornamentals. This section shall be known as the Ornamental Section of the Florida State Horticultural Society. It shall be presided over by a Vice President, who shall be elected at

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VIII FLORIDA STATE HORTICULTURAL SOCIETY, 1950 each annual meeting of the . Society by the members in attendance at the Ses sion. The Vice President shall be an ex-officio member of the Executive Com mittee. Article 12. A section of the annual program of the Society shall be devoted to the discussion of processing. This sectipn shall be known as the Processing Section of the Florida State Horticultural Society. It shall be presided over by a Vice President, who shall be elected at each annual meeting of the Society by the members in attendance at the Ses sion. The Vice President shall be an ex-officio member of the Executive Com mittee. BY-LAWS 1. The Society year shall be coexten sive with the calendar year, and the an nual dues of members shall be four dollars. 2. All bills authorized by the Society or its Executive Committee, for its legi timate expenses, shall be paid by the Sec retary's draft on the Treasurer, O.K'd by the President. 3. The meetings of the Society shall be devoted only to Horticultural topics, from scientific and practical standpoints, and the presiding officer shall rule out of order all motions, resolutions and discus sions tending to commit the Society to partisan politics or mercantile ventures. 4. All patron and life membership dues and all donations, unless otherwise speci fied by donor, shall be invested by the Treasurer in United States Government bonds . The earnings from these bonds shall be left as accrued values or rein vested in United States Government bonds of a guaranteed periodical value unless it is ordered by the Executive Committee or the Society that such earn ings can be made available for operating expense. Receipts from perennial mem bership dues shall be placed on deposit at interest by the Treasui;er. Only three dollars ($3.00) from each perennial mem bership fee shall be available during any calendar year for payment of operating expenses of the Society.

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FLORIDA STATE HORTICULTURAL SOCIETY, 1950 IX AWARD OF HONORARY MEMBERSHIPS FOR MERITORIOUS SERVICE TO FLORIDA AGRICULTURE MR. JAMES _HARDIN PETERSON of Lakeland, Fla., born in Batesburg, South Carolina, February 11, 1894; graduate of Lakeland High School and of the College of Law of the University of Florida, receiving LL.B. degree; Doc tor of lf umanities, Fla . Southern Col lege; admitted to the Bar in 1914; in his early practice, specialized in Municipal Law. He served several terms as Chair man of the Legislative Committee of the Florida League of Municipalities; special counsel for the Department of Agricul ture, State of Florida; se1;ved in the Navy during World War I. He was elected to the Congress on November 8, 1932; reelected continuously up to and including the present Congress; volun tarily retiring on January 1, 1951. During his happy and productive rep resentation of Florida in the Congress, Mr. Peterson has developed, and shown repeatedly, not only a keen interest in horticulture and other important inter ests, but a profound knowledge of them. This knowledge, coupled with his earnest desire to be of worthwhile public service, has been a tremendous profit to horticul ture on many occasions. He has beeri an active citrus grower in Florida for many years. Known widely as the outstanding committee worker in the Congress, his work as a Member and Chairman of the Public Lands Committee has meant much to this country in dealing with public lands and natural resources. Mr. Peter son has served horticulture and other in terests of Florida with real distinction. DR. A VERY S. HOYT was born in San Diego, California, on September 16, 1888. He was graduated from Pomona College, California, in 1910 with a BSA degree. Following his graduation he en tered the employ of the California State Department of Agriculture, and was as signed to plant quarantine enforcement activities. He occupied various positions of responsibility within that organiza tion, and in 1928 he was appointed Di rector. In 1931, he went to Washington to be come Assistant Chief of the Plant Quar antine and Control Administration. In 1934, he was selected to serve as Assist ant Chief of the newly created Bureau of Entomology and Plant Quarantine. By reason of meritorious service he was ad vanced to the position of Associate Chief in 1941. On April 12, 1950, he was made Chief of the Bureau of Entomology and Plant Quarantine to fill the vacancy brought about by the death of Dr. P. N. Annand . Dr. Hoyt's contributions to the agri culture of the nation have been largely in the field of plant quarantine. His early . experiences in California convinced him of the need for taking all possible action to protect the several states from insects and disease from abroad, particularly states like California, Texas, Florida , and others which are peculiarly exposed to invasion by reason of geographical locations and international travel and trade. Throughout his service as a fed eral official he has endeavored to pro vide this protection while adhering to a strict scientific basis for all of his official actions, in spite of pressure brought to bear from many sources. DR. HAROLD MOWRY came to Flor ida in 1916 from Kansas and Colorado. During the ensuing thirty-four years his record of significant contributions to our horticultural industry has not only added millions of dollars to the income of our State, but through his zeal, his complete ly unselfish and devoted service, his

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X FLORIDA STATE HORTICULTURAL SOCIETY , 1950 loyalty to high ideals, and his friendly and sincere manner, he has carved for himself a place in the hearts of the mem bers of this Society. His numerous scientific contributions are widely recognized. With the Florida State Plant Board he contributed to the eradication of Citrus Canker and the Mediterranean Fruit Fly. With the Flor ida Agricultural Experiment Station his original research pointed the way to the important role of the minor elements in plant nutrition on the mineral soils of the State. He is an undisputed authority on the culture and botany of Florida's ornamental trees and shrubs, and of many of her fruits. His careful experi ments became the foundation on which our Tung industry developed. While with the Experiment Station, he was author of thirteen of its most widely read bulle tins, and has written hundreds of articles for scientific and popular journals. In addition, he has written thousands of letters to individuals, helping in the solution of their horticultural problems, not only in Floriqa, _ but all over the world. He retired on January 31, 1950 as Director of the University of Florida Agricultural Experiment Station, to which position he advanced through the ranks from Assistant Horticulturist. As Director his ability resulted in the growth of his organization to a position where it is now one of the largest in the Nation, with a world-wide reputation for the high standards and productivity of its research. With all this he has remained a modest man and a loyal friend. He is deserving of the highest honor that this Society can confer.

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FLORIDA STATE HORTICULTUHAL SOCIETY, 1950 XI LIST OF MEMBERS HONORARY MEMBERS Fair c hild, Dr . D avi d, Coconut Grove Haden, !\!rs. Florence P ., Co co nut Grov e Hastings, H. C ., Atlanta, G eo rgia Henricksen, H. C ., Eustis Holl a nd, Spessard L., Bartow Hoyt, Dr. Avery S., Wasington, D. C. Hume, Dr. H. Harold, Gain es ville Lipsey, L . W., Bl an ton Mayo, Nathan, Tallahassee Mowry, Dr. Harold , Gainesville Peterson, J. Hardin, Lakeland Robinson , T. Ralph, T e rra Ceia Swingle , Dr. \V, T ., 'Washington, D. C . PATRON MEMBERS An1erican Agricultural Chemical Company, Pierce American Fruit. Crowers, Inc ., ~faitland Angebilt Hotel, Orlando Armour Fertiliz er \Vorks, Jack so nville Buckeye Nurseries Chas e & Company, Sanford D ee rfield Groves , Wabasso D ee ring, Charl es Exchange Supply Company , Tampa Exotic Gardens , Miami Florida Citrus Exchange, Tampa Florida East Coast Hotel Co ., St. Augustine Florida Grower Pnh li shing Co . , Tampa Th e Fruitland s Co . , Lake Alfred Gardn e r, F. C. , Lake AUred Gl e n St. ~larys Nurseries Co., Glen St. ?-.tarys Gulf Fertilizer Co., Tampa Hastings , H. G. Co. , Atlanta, G eo rgia Hillsboro Hotel, Tampa Klemm, A. ~ , f. & Son , \Vinter H ave n Lake Garfield Nurs e rie s, Bartow l'\fanate e Fruit Company, Palmetto Mills Th e Florist, Jacksonville Nocat ee Fruit Co .. Nocatee Oklawaha Nurseri es Co., Inc., L a ke Jem Southern Crate Manufacturing Assn . Stead, Lindsay, Box 809, Ft. Pierce Thomas Advertising S e rvice U. S. Phosphoric Products, Division Tenness ee Corp., 61 N. Broadway, New York, N. Y. U. S. Phosphoric Products , Divi s ion Tenn e ss ee Corp ., !lox 3269, Tampa Van Fl ee t Co., \Vinter Haven \Vilson & Toomer Fcrti1izer Co . , Jacksonvill e LIFE MEMBERS Agricultural Exp e riment Station, Puerto Rico Alb e rtson Public Library, Orlando Allenbrand , Alfred, Box 288 , Frostproof Ald e rman, A. D., Bartow Andrews. C. W . ~ John Crerar Library, Chi cag o, Illinois Barber, C. F ., :\facclenny Bartlum. \V. L eona rd, Florida Agricnltnral Supply Co ., Orlando B e rg e r, Mrs. E. \V., Gainesvill e Boui s, Clarence G., Box 6, Ft. Meade Bringham, M. S., Micco Britt, John F ., Ft. Pierce Brown, A . C., Gainesville Bullard, Henry F., Bullard & Sprott, Lake Wales Carn eg ie, Mrs. T. M., Fernandina Champlain, A. E . , R 3, No. 1, Palmetto Chid es ter, D. iJ. , 446 Paint e r Ave., Whittier, California Chri stia ncy, C o rn e lius , Port Orange Cl e m e nt, \Valdo P . , Georgiana Coitnei\ \Vayii.C E., New Smyrna Cook, R. F., Leesburg County Agent, Orange County, Orlando Cmtchfield & \Voolfolk, P e nnsylvania Produce Bldg ., Pittsburgh, Pennsylvania Dun e din Puh1ic Lihrary, Dunedin Ellsworth, Wilma J. (Miss), Rt. No. 1, Dad e City Fairchild, Dr. David , Coconut Grove Fugaz z i, John , Fuga zz i Brothers. Cl ea rwater Gilford, Dr. John, Coconut Grove Guest, Mrs. Amy, N. Ocean Blvd., Palm Beach Haden, Mrs. Flor e nc e P., Coconut Grove Hakes, L. A., Box 771, Orlando . Hastings, H . G., 16 W. Mitchell St., Atlanta , Geor)(ia Henricks e n, H. C., Box 1045, Eustis Hernand ez, Pedro, 108 Cienfuegos, San Fernando, Cuba Hollingsworth, G. S., Arcadia Hume, H. Harold, Gainesville Iowa State College Library, Ames, Iowa Jaco cks, A. J., Winter Haven Lassen, H. C., Garden Spring T e rrace, Saratoga; California Lauman, G . N., Ithaca, N. Y. Leonard, George V . , Hastings !lfanat ec _ Ftliit Co _ ., 1 s t National Bank Bldg. ; Tampa Martin, A ._ \Vm., Box _ 36, Sebastian Mathew s, E. L., Plymouth :\!cCarty, B. K., Eldred McCarty, Mrs. C . T., Eldred Merritt , Dr. J. C., 297 Sherman St., St. Paul Minnesota Michael, A. ll., Wabasso

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XII FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Montgomery, Robert H. (Col.), Coconut Grove Montgomery, Mrs. Robert H., Coconut Grove Morrell, Albert, Orlando Mountain Lake Corporation, Lake Wales O'Byrne, Frank M., Lake Wales Ohmer, C. J., West Palm Beach Olivebaum, J. E., Clermont Pedersen, W. L., Winter Haven Pennock, Henry, Sr., Jupiter Phillips, Howard, Orlando Phipps, John S., N. Ocean Blvd ., Palm Beach Phipps, H. C ., N. Ocean Blvd., Palm Beach Phipps, Howard, Delray Beach Pike, W. N., Blanton Plymouth Citms Growers Assn., Plymouth Prosser, Lew, Plant City Raulerson, J. Ed, Arcadia Reasoner, N. A., Bradenton Reid, W. C ., Largo Rohde, H., Sebring RicketsOn, Mrs. M. C., "Grayfield," Fernandina Sample, J. W., Haines City Sandlin, A. R., Leesburg Schuman, Albert, Sebastian Sellards, Dr. E. H., State Geologist, Austin, Texas Sevil , Mrs. Sara L . , Fort Myers Sloan, G. D., Box 1021, Tampa Stanton, F. W., Dock & Walnut Sts., Philadelphia, Pennsylvania Stead, Lindsay, Box 809, Ft. Pierce Stevens, Edmund, Verge Alta, Puerto Rico Stuart, L. E., Montemorelos, Mexico Taber, Mrs. George L., Glen St. Marys Taylor, J. S., Largo Thomas, Jefferson, Gainesville Todd, E. G., Avon Park Towns, Thomas R., Holguin, Cuba Trelease, Wm., University of Illinois, Urbana, lllinois Trueman, Roy B., Trueman Fertilizer Company, Jacksonville Von Borowsky, Miss Lisa, Brooksville Wilson & Toomer Fertilizer Co., Box 4459, Jacksonville Wirt, E. L . , Box 144, Babson Park Yothers, ,v. W., 457 Boone St., Orlando SUSTAINING MEMBERS Adams Packing Assn., Inc., Box Drawer HB," Auburndale Allen, Ruth Stuart, P. 0. Box 804 (Tropical Gardening), Coral Gables American Cyanamid Company, 30 Rockefeller Plaza, New York 20, N. Y. American Fruit Growers, .Jnc., Ft . Pierce Austin, Guy D., and Co., Miami 35 Babb, Herbert A., Gulf Fertilizer Co., Umatilla Barber, Bascom D., Wilson & Toomer Fertilizer Co., Box 685, Clearwater Bellows, Dr. J. M., Hector Supply Co., Miami Bergstrom Trading Company, Inc., 233 Broadway, New York 7, N. Y. Bland, W. T . , American Fruit Growers, Lake Jem Brady, R. C., NACO Fertilizer Co., Titusville Brooks, J. R. Box 36, Homest e ad Broward Grain and Supply Co., Inc., Ft. Lauderdale Browder, David, Box 310, Arcadia Bryan, L. T., Fosgate Growers Coop., Box 2673, Orlando Burpee, w. Atlee Co., Sanford Burrichter, A., Box 42, Homestead California Spray Chemical Co ., Box 1231, Orlando Campbell, John W., Goulds Carleton, R. T., Plymouth Cartledge, Raymond H., Cartledge Fertilizer Co ., Cottondale Charles, Wilber G., Florence Citrus Growers Assn ,, Florence Villa Chase, Randall, Box 291, Sanford ClaJk, Everett B., Associated Seed Growers, Inc., Walcaid Bldg., Bradenton Clark, John D., Waverly Clark, S. W . , Agricultural Department, Texas Gulf Sulphur Co., 1002 Second National Bank Bldg., Houston 2, Texas Clinton Foods., Inc . , Dunedin Conkling, W. Donald, Citrus Culture Corp., Mt. Dora Cooper, George H., Glade & Grove Supply Co., Box 198, Princeton Cooper, R. K., Florence Foods lnc. , Florence Vi1la Crum, H. M., International Minerals & Chemical Corp., 908 Mortgage Guarantee Bldg., Atlanta 3, Ga. Dabney, B. G., Coronet Phosphate Co., Plant City Dancy, R. C., Jackson Grain Co., Cass & Ashley Sts., Tampa DiGiorgio Fruit Corp., Winter Haven Dixie Lime Products Co., Box 578, Ocala Dolomite Products Inc., Box 578, Ocala Dozier, G. L., NACO Fertilizer Co., Box 232, McIntosh Duda, Andrea, Jr., A. Duda & Sons, Oviedo Duda, Ferdinand, A. Duda & Sons, Oviedo Dundee Citrus Growers Assn., Dundee Dye, Alfred M., Everglades Fertilizer Co., Box 821, Ft. Lauderdale Dye , John B., Jr., Everglades Fertilizer Co., Box 821, Ft. Lauderdale Edsall, R. S., 1828 28th Ave., Vero Beach Faircloth, E. V., 2829 South Dixie, West Paint Beach Faircloth Truck-Tractor Co,, 2829 South Dixie, West Palm Beach Florida Agricultural Research Institute, Box 392, Winter Haven Florida Citrus Canners Coop., Lake Wales Florida Citrus Exchange, Box 2349, Tampa 1 Florida Citrus Production Credit Assn., Box 2111, Orlando Florida Dolomite Co., Pembroke Florida Fruit & Vegetable Assn., 29 South Court St., Orlando Florida Seed and Feed Co . , Ocala Fortner, J. E., Citrus Culture Corp., Mt; Dora Fudge, Dr. B. R.; Wilson & Toomer Fertilizer Co_., P. O. Drawer 4459, Jacksonville Grant, A. J., 259 Scotland St., Dunedin Green, William F., Wilson & Toomer Fertilizer Co., P. 0. Drawer 4459, Jacksonville Greenwood Products Co., Graceville Growers Fertilizer Coop., Lake Alfred Hagadorn, D L., Jackson Grain Co., Cass & Ashley Sts., Tampa

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FLORIDA STATE HORTICULTURAL SOCIETY, 1950 XIII Hagar , Jack, Fosgate Growers Coop . , Box 2672, Orlando Haines City Citrus Growers Assn., Haines City Haines City Heights, Inc., Haines City Hawkins, Howard, Box 410, St. Augustin e Heller Brothers Packing Co., Winter Garden Henderson, Fred F., Winter Haven Hicks , W . B., Wilson & Toomer Fertiliz e r Co., P. 0. Drawer 4459, Jacksonville Hinson, Alvin H., Box 868, Plant City Holland, Frank L . , 324 Ave. B., NE, Wint e r Haven Horton , W. D:, Collins Feed & Supply Co., . N. E. 94th & FEC R'way, Miami 38 Howard, J. D., Howard Fertilizer Co., Orlando Howard, R . M., Howard Fertilizer Co., Orlando How e ll , Morton , \Vaverly Growers Coop. , Waverly Hunt, D. A. , Florida Citrus Canners Coop., Lake Wales Immokalee Growers, Inc., c/o J. T. Gaunt, Immokalee Jackson, R. D., Jackson Grain Co., Cass & Ashley Sts., Tampa Jamison, J. R., Deerfield Groves Co., Wabasso Jones, R. S., Wilson & Toomer Fertilizer Co., P. O. Drawer 4459, Jacksonville Jungle Gardens, Sarasota Kime, C. D., Jr., Waverly Growers Coop., Waverly Kinnard, R . R., Gulf Fertilizer Co., Box 607, Hom e stead King, Battey, Naples Kinsey, L . P., Box 878, Winter Haven Kirtley, A. G., Dundee Citrus Grow e rs Assn . , Box 1121, Winter Haven Klee, W. H., NACO Fertilizer Co.,-Jacksonville 1 Klemm, A. M. & Son, Winter Haven Laird, Norman N., Waverly Growers Coop, Waverly Lake County Citrus Sales., c/o Bruce Floyd, Leesburg Le e , C. S., Box 225, Oviedo Lesl e y, John T., Haines City Citrus Grow e rs Assn., Haines City L i ns, E. W., American Fruit Growers, Inc., Fee Bldg., Ft. Pierce Little , C. S., Superior Fertilizer Co., Odessa Lucas, Glen H., Peninsular Fertilizer Co., Box 2989, Tampa 1 MacDonald, R. M., Chester Groves Co., City Point McLain, L. Rogers, Gulf Fertilizer Co., Box 2721, Tampa 1 McLane, \V , F., Lyons Fertilizer Co., Box 310, Tampa McSweeney, W. M., Gulf Fertilizer Co . , Box 2721, Tampa I Marrs, G. F., Superior Fertilizer Co., 914% McBerry, Tampa Matheson, Hugh M., 418 S. W. 2nd Ave., Miami 36 Mathias, A. F., Superior Fertilizer Co., Box 183, Lake Hamilton Maughan, D. B., California Spray-Chemical Co., Orlando Maxwell, Lewis, Jackson Grain Co ., Cass & Ashley Sts,, Tampa Maxcy L . , Inc., Frostproof M e rshon, Claud C., Fosgate Growers Coop ., Box 2673, Orlando Messec, Murrel, Gulf Fertilizer Co., Box 687, Bradenton Micha e l , A. B., Deerfield Groves Co., Wabasso Mitchell, Edward C., Citrus Culture Corp., Mt. Dora Mount Dora Growers Coop., Mount Dora Oslo Citrus Growers Assn., Oslo Palm Harbor Citrus Growers Assn., Palm Harbor Pasco Packing Co. , Dade City Pedersen, W. C., Waverly Growers Coop., Waverly Perrin & Thompson, Inc . , Box 1000, Winter Haven Pinellas Growers Assn . , Clearwater Pinkerton, J. B. , Ch e ster Groves Co., City Point Plummer, Dr. J. K., Tenn. Corp. Research Lah., 900 Roosevelt Hwy., College Park, Ga. Plymouth Citrus Growers Assn., Plymouth Prevatt, J. B., Lake Region Pkg. Assn., Tavares Price, R. C., Florida Agri. Supply Co., Box 658, Jacksonville 1 Prine, Henry A. , Domino Citrus Assn., Inc., Box 179, Bradenton Prine, R. H., Box 85, Terra Ceia Producers Supply, Inc., Palmetto Raoul, Loring , Box 871 , Sarasota Reed, R. R . , Gulf Fertilizer Co., P. 0 . Box 2721, Tampa Richardson, D. K ., 2664 19th St., Vero Beach Richardson, E. G., 235 S. Indian River Drive, Ft. Pierce Rickborn, J. H., Lyons Fertilizer Co., Box 310, Tampa Roess, M. J ., Box 388, Jacksonville Rothwell, A. D., Superior Fertilizer Co., 1407 Hesperides, Tampa Ruskin Vegetable Distributors, Ruskin Ryburn, Alexand e r W., Box 977, Vero Beach Sachs, Ward H., Box 3588, Orlando Sample, James M., Lyons Fertilizer Co., Box 310, Tampa Sarasota Jungl e Nurseries, Sarasota Seidel, G. A., Box 7, Gotha Sheffield, J. R., Coronet Phosphate Co., 19 Rector St., New York 6, N. Y. Shields, J. C., Domino Citrus Assn., Inc., Box 179, Bradenton Skinner, B. C., Dunedin Skinner, F. L., 379 Monroe St., Dunedin Sloan, G. Dexter, Sup e rior Fertilizer Co., Box 1021, Tampa Slough Grove Co., Inc., Dade City Smith, F. M . , Howard Fertilizer Co., Orlando Smith, Herbert A . , Jr . , 1019 Lancaster Drive, Orlando Snively, John A . , Jr. , Eloise Groves Assn., Winter Haven Snively , T. V., Box 10, Winter Haven South Florida Motor Co ., Box 151, Sebring South Lake Apopka Citrus Growers Assn., Oakland Speights, J. A., Ev e rglades Fertilizer Co., Box 821, Fort Lauderdal e Spencer, T . C., Haines City Stewart Packing Coop., Box 324, Auburndale Swann, Tom B., Box 232, Winter Haven Tennessee Corp., Research Laboratories, 900 Roosevelt Highway, College Park, Ga. Thomas, Wayne, Box 831, Plant City Thullbery, C. C., Lake Region Pkg. Assn., Tavares Tilden, A. M . , Box 797, Winter Haven Tilden, L. W., Winter Garden Tomelaine Groves, Winter Haven Tucket, Inc., Minneola Van Hom, M. C., Florida Agri. Supply Co., Box 658, Jacksonville 1 Virginia-Carolina Chemical Corp., Orlando Walker, Eli C., Jr . , Box 796, Vero Beach Ward'.s Nursery, Box 177, Avon Park

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XIV FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Waring , W. L., Jr., Lyons Fertilizer Co., Box 310, Tampa Waverly Fertilizer Works, Waverly Waverly Growers Coop., Waverly Wetumpka Fruit Co., Box N, Hastings Wh ee ler Fertilizer Co., Oviedo Whitfield, Charles S., Amherst Apts., Orlando 'vVilson, Homer A., Gulf Fertilizer Co., Box 746, Ft. Pierce Winter Park Land Company, 128 Park Ave. S., Winter Park \Volfe, J. C., Lyons Fertilizer Co., Box 310, Tampa Wood, Wade W., Gulf Fertilizer Co., Box 634, DeLand Woodlea Grov es, Box 144, Tavares Woodruff, F. H . & Sons Inc., 695 Glenn St ., S. W., Station A, Box 164, Atlanta, Ga. Woods, Fred J. , Gulf Fertilizer Co., Box 2721, Tampa Woods, J, Albert, Wilson & Toomer Fertilizer Co., P. 0. Drawer 4459, Jacksonville Woods, Lem P., Gulf Fertilizer Co., Box 2721, Tampa 1 Wray, Floyd L., Box 1782, Flamingo Groves, Inc., Ft. Lauderdale Yager, Alonzo, Waverly Growers Coop., Waverly Yandre, Thomas E., Farm & Home Machinery Inc., Box 3547, Orlando ANNUAL As of February 26, 1951 Abbey, 0. H., P. 0. Box 27, Ft. Lauderdale Abbott, Fred P., Room 105, Union Station, Savannah, Ga. Adams Packing Assn. Inc., Drawer B, Auburndale Alexander, J. F., Box 154, Bartow Alexander, Taylor R., Botany Dept. Univ. of Miami, Miami Allen, E. J . , 2150 N. W. 17th Ave., Miami Allison, R. V., Everglades Exp. Sta,, Box 37, Belle Glade Am e rican Cyanamid Co., 30 Rockefell e r Plaza, New York 20, N . Y . AmNican Fruit Grower Publishing Co. , 106 Euclid Ave., Willoughby, Ohio American Potash & Chemical Co ., Atlanta, Ga. American Potash Institute, Am. Chemical Soc. Bldg., 1155 16th St. N. W., Washington 6, D. C. Andrews, W. R. E., 1505 Race St., Philadelphia 2, Pa. Angel, L. B., Haines City Appleton, Shelton, Box 2281, Lakeland Armour Fertilizer Works, P. 0. Box 599, Jacksonville Arzave, Genaro, P. Mier 328 Ote., Monterey, N. L. Mexico Atkins, C. D., Box 443, Rt. No. 1, Winter Haven Ayers, Ed L., County Agent, Palmetto Backus, F. E., Box 283, Frostproof Bailey, E. R . , Sanibel Baker, A. L., Box 247, Lakeland Baldwin, Mrs. Porter, 308 Monroe Drive , West Palm Beach Ballentine, C. C., P. 0. Box 3751, Orlando Barber, B. D., Box 685, Clearwater Barcus, David F., Box 601, Ft. Pierce Barker, J. P., Box 1131, Winter Haven Barksdale, D. N., Box 2567, Mulberry Barnett, Joe P., c/o American Fn1it Growers, Inc., Ft. Pierce Barrus, Mrs. Edith, Tallahassee Bartz, Paul, 306 S. E., 12th, Ft. Lauderdale Baskin, J. L., 1230 Golden Lane, Orlando B as s, C. A., 82 N. W. 34th St., Miami Beardsley Farms, Clewiston Beckenbach, J. R., Asso , Director, Fla. Agr . . Exp . Station, Gainesville Beerhalt e r, A., Rt. No. 3, Box 300, Ft. Pierce B eise l, C. G., Real Gold Citrus Products, Box 230, Anaheim, California Benitez, Lie, Jose, Edificio La Nacional, 311 Monterrey, N, L. Mexico Bennett, Charl es A., 1825 N. W. 21st, Miami 37 Berry, James, 332 "E" S. E., Winter Haven Bickner, Charles , P. 0. Box 1282, Bradenton Biebel, Joseph R., 312 No. 4 Rd., S. Miami 43 Biggins, Harry N ., Box 58, Clearwater Bissett, Arthur M ., Box 66, Winter Haven Bissett, Owen, 1340 Lake Mirror Drive, Winter Haven Blackmon, G. H., Agri. Exp. Sta., Gainesville Bodine, E. W ., 50 W. ,50th St., Shell Chemical. New York, N. Y. Boswell, Ralph, 206 E. Amelia St., Orlando Bourne, Dr. B. A ., Box 6368, Clewiston Boyd , F. E ., Box 120, Montgomery, Ala. Boyd, Thos. M., Rt. No. 1, Box 408, Winter Haven Bradbury, Charl es 0., Rt. No. 2, Winter Haven Bragdon, K. E., Indian River City Bristow, J. J. R., Juice Industries, Inc., Dunedin Brockway, E. K., Box 695, Clermont Brokaw, C. H., Minut e Maid, Plymouth Brooks, A. N . , Box 522, Lakeland Brooks, J, H., DiGiorgio Fruit Corp., Box 1352, Ft. Pierce Brown, C. H., Box 601, Ft. Pierce Brown, Glenn, Tavares Brown, M. R., Box 575, Winter Haven Brown, R . E., Lake Wales Brown, R. L., NACO Fertilizer Co., Ft. Piere<' Brown , T. 0., Box 96, Frostproof Brown, Mrs. V. L. St a nford St., Bartow Bryan, D. S., 510 S. Broadway, Bartow Bryan, R. L., Box 154, Bartow Buckles, W. V., P. O. Box 86, Leesburg Bullard, Henry, Lake Wales Burch, R. W., Inc., Plant City Burden, Georg e F., P . 0. Box 935, Winter Haven Burgis, Donald S. , Box 678, Manatee Station, Bradenton Burns, Theodore C ., Box 308, Palmetto Butcher, F. Gray, Univ. of Miami, Coral Gables Cadmus, Harold J,, 3817 San Pedro, Tampa 9 California Fruit Growers Exchange, Research Dept . , 616 E . Grove St., Ontario, California Call, A. H., 13472 Burto St ., Anaheim, California Calumet & Hecla Consolidated Copper Co., Calumet, Mich. Camp, Dr. A. F., Citrus Exp. Sta., Lake Alfred Carlton, R. A., P. 0. Box 1896, West Palm Beach Casseres, Ernest H., Dept. of Veg. Crops, Cornell, . Univ., Ithaca, N. Y.

PAGE 14

FLORIDA STATE HORTICULTURAL SOCIETY, 19.50 xv Central Groves Cooperative, Lake Hamilton Chandler, L. L., Goulds Chase, Frank K., 1819 Cherokee Trail, Lakeland Chase, Frank W., Jsleworth, Windermere Chase, Randall, Box 291, Sanford Chase, Sydney 0., Jr,, P. O. Box 599 , Sanford Chipman Chemical Co., Inc., Box 309, Bound Brooks, N. J, Chissom, G. A., 1200 Sunshine Ave., Le es burg Chronister, B . S., 1108 E. Main St., Richmond, Va . Citrus Grove Development Co., Babson Park Clayton, H. G., Hort. Bldg., Univ. of Fla., Gainesville Clearwater Growers Assn., Box 299, Cl ea rwater Clements, W. B., Box 65, Leesburg Coastes, J. L ., Adams Packing Assn., Inc . , Auburndale Coe, Dr. Dana G., 1425 Providenc e Rd ., Lakeland Coe, Ray, Star Route, Bunnell Coleman, K., Speed Sprayer Co., Orlando Collins, Paul F ., Haines City Colter, R. L ., Box 830, Lakeland Commander, C . C., Box 2349, Tampa Connell, Ed . B., Rt. No. 1, Box 502, Valrico Connor, F. M., P. 0. Box 265, Palm e tto Conover, Robert A., Sub-Tropical Exp. Sta . , Homestead Cooney, Ray H., 1007 Wallace S. Bldg . , Tampa Cooper, William C., Box 241, \Veslaco, Texas Costa, Dr. A. S., USDA, Institute Agronimico, Campinas, Brazil Covington, D. D., Jr., Covington Fruit Pkg. Co., Dade City Cowperthwaite , W. G., Veg. Crops Lab., Box 678, Manatee Sta., Brad e nton Crawford, Mrs. W. T., Haines City Creighton, John T., Box 2845, Univ . Sta., Gainesville Crenshaw-McMichae\ Seed Co., Box 1314, Tampa 1 Crews , Standish L., Box 179, Vero Beach Crossman, W. F.; Fla. Southern College, Pi Kappa Alpha, Lakeland Crumb, Frank K., Box 307, Lakeland Crutchfield, Cecil M., Box 555, Auburndale Curry, Kenneth, 1618 Rose Ave., Knoxville 16, Tenn . Croce, Francisco M., Matienzo 339, San Jose, Mendoza, Argentina D'Albora, John V., Jr., Box 1189, Cocoa D a ly, C. F., West Coast F ert. Co. , Box 1094, Tampa 1 Davis, Charles P., Box 947, Winter Haven Day, William A., Box 29, Bradenton Decker, Phares, Agr. Exp. Sta., Gain es ville D e kle, George W., State Plant, Gainesville Dennison, Raymond A., Dept. of Hort . , Fla. Agr . Exp. Sta., Gainesville D'Ercole, A., 308 Windsor St., Lak e land Dewson, I. B., 424 Ard e n Court, Ridg ewo od, N. J. Diamond R . Fertilizer Co . , Inc., Winter Garden Dickey, R. D ., P . O. Box 2845, 'Univ. Sta., Gainesville Dickman, Lyle C., Ruskin Dickman, Paul B., Ruskin Diem, John J . , Southern Agri. Insecticides, Inc., Palmetto Di e rberger Agro-Comm e rcial LTDA . , Caixa Postal 458, S. Paulo, Brazil Dijkman, Dr . M. J., 4013 Douglas Rd ., Coconut Grove, Miami Dixon, W . R., P. 0. Box 144, Winter Garden Dolan, F . M., 1817 Granada Blvd . , Coral Gables Donaldson, C. S., Avon Park Dowden, R. S., Box 1907, Orlando Dowling , Paul 11., 1644 E. Livingston, Orlando Drondoski, John E ., Box 1225, Ft. Pierc e Dunlap, R. C., Box 668, Hialeah Dunn e, Hugh J., San Antonio Dy e, H. W., Niagara Chem . Div., Food Machinery & Chem. Corp ., Middl epo rt, N. Y. Dyson, z. V., Orio Vista Eaton, DeWitt, Box 142, Sarasota Eddins , Dr. A. H., Potato L abo ratory, Hastings Edsall, R. S ., 1828 28th Ave., Vero Beach Eide, Andrew, c/o J. C. Sample, Naples Elvin, Evert, Citrus Exp. Sta., Lake Alfr e d Enzi e, W. D., BirdsEye Snid e r Div., 40 Franklin St., Rochest e r N. Y. Este s, H . 0 ., Box 835, Haines City Evans, Thomas E ., Box ll05, Lake Alfred Ever gla des Fertilizer Co., Ft. Lauderdal e Fasc e ll, Micha e l, 1661 S. W. 22nd St., Miami Fawsett, C. F., Jr ., Box 186, Orlando Fe as t e r, O. 0., Rt. No. 1, Box 740, Lakeland Felton, E. R., Lak elan d Feu ste l, Wm. K., Rt. T. Vanderbilt Co., 230 Park Ave., N ew York 17, N . Y . Fi elds, Charles E., Box 532, Winter Haven Fifi e ld, ,vmard M ., Agr. Exp. Sta . , Gainesville Fisher, Miss Francine E., Citru s Exp. Sta., L ake Alfred Fitzpatrick, Thom as E., Box 572, Haines Cit)' Fla. Chamber of Commerce, Jacksonville Florida Geologi ca l Survey, T a llahassee Fogg, Harry W., Box 774, Eustis Food Machinery Corp., John Bean Div., 1312 W. Washington St., Orlando Ford, Dr. Harry W., Citrus Exp. Sta., Lake Alfred Ford, Robert, 218 E. Bay St., Lakeland Forsee, Dr. W. T . , Jr ., Everglades Exp. Sta ., Belle Glade Foy , John E., Jr., Ashcraft-Wilkinson Co. , Wallace S. Bldg., Tampa 2 Free ze, Walter, Box 2470, Clearwater Friend Sprayer S e rvice Corp., Frostproof Fr ie nd, W. H ., Box 548, Weslaco, Texas Frierson, Paul E. , State Plant Board, Gainesville Frisbie, S. Lloyd, Bartow Futch, Ivey E., Box 857, Lake Placid Gain esv ille Garden Club, c/o Mrs. James W. Day, Pres., 530 N . E. 7th Ave ., Gainesville Galla g her, Vinc en t, 13 N. E. 13th St., D e lray Beach Gardner, Mrs. F. C., Lake Alfred Gardner, Dr . Frank E., 415 Parramore St., Orlando Garr e tt, Charles A ., RFD 1, Box 216, Kissimmee Gates, Charles M . , Univ. of Miami, Coral Gables Gerwe, Dr. R. D . , Food Mach. & Chem. Corp., Lakeland Gill , B. R., Rt. No. l, Ft. Lauderdale Glass, Mrs. E. L., Haines City Gould, Ch es ter N . , Star Rt . Box 23, West Palm Reach Grant, Dr. Theo J ., USDA, Institute Agronimico, Campinas, Brazil Gratz, L. 0., Agr. Exp. St a ., Gainesvill e Grav es, Forrest C . , Box 606, Vero Beach Graves, J. R., Box 922, Vero B ea ch Gre en, W. F., Wilson & Toom e r Fertiliz e r Co., Jacksonvill e Green e, Barnett e E., Jr., Vero Beach Gr ee ne, R. E . L ., Departm en t of Agr. Econ., U. of Fla . , Gainesville Gri eneise n, L., Jr., Weirsdate

PAGE 15

XVI FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Griffin, B. H., Jr., Box 155, Frostproof Griffin, J. A., Box 1809, Tampa 1 Griffiths, J. T., Citrus Exp. Sta., Lake Alfred Groebe, Russell A., Box 1429, Cocoa Groff, G. Weidman, Laurel Groff, H. C., Palmetto Groover, Ben H., Lake City Grossenbacher, J. G., Plymouth Grossenbacher, S. A., Box 66, Apopka Goldroeber S., U. of Miami, Box 1015, S. Miami Grove, Wm. R., Laurel Growers Fertilizer Agency, Lake Alfred Guest, Mrs. Amy, 465 E. 57th St., New York, N. Y. Gunn, C. D., Rt. No. 1, Micanopy Hale, Roger H., Rt. No. 1, Palmetto Hall, C. B., U. of Fla., Horticulture Dept., Gainesville Halsey, L. H., Fla. Agr. Exp. Sta., Gainesville Halter, E. T., Box 110, Palm Beach Hamilton, Joseph, Rt. No. l, Box 798, Yuma, Arizona Hamilton, Mrs. Madelaine, 630 Ave., B., N.W., Winter Haven Hamm, Freeman R., City of Lakeland, St. Dept., Lakeland Hammerstein, C. P., Hammerstein Groves, Hollywood Hanna, L. C., Hanna Rd., Lutz Harding, Dr. Paul L., U.S.D.A., Orlando Harkeson, J. E., 624-7th St., N.W., Winter Haven Harkness, R. W., Sub-Tropical Exp. Sta., Homestead Harshman, W. W., Highlands Fertilizer Co., Sebring Hardwick, J. E., Jr., P. 0. Box 669, West Palm Beach Harz, A. W., 13 W. Underwood Ave., Orlando Hartt & Son, Inc., Box 308, Avon Park Hatch, Hugh B., Dunedin Hayman, W. Paul, P. 0. Box 711, Bartow Hayslip, Norman C., Box 1198, Ft. Pierce Hayter, W. Burns, P. 0. Box 536, Leesburg Hayward, Wyndham, Lakemont Gardens, Winter Park Hector Supply Co., Box L No. 1311, Miami Heindrick, E. P., 5830 N.W. 7th Ave., Miami Henderson, H. Cecil, Box 1448, Winter Haven Hendrickson, Rudolph, Citrus Exp. Sta., Lake Alfred Hennes, Jaffa E., S. Lake Apopka Citrus Growers Assn., Oakland Henry, Arthur M., 1177 Zimmer Dr., N.E., Atlanta, Ga. Henry, W. M., Box 508, Plant City Herlong, Byron, Le . esburg Hill, Arhur M., Jr., Box 306, Vero Beach Hills, Walter A., P. 0. Box 1055, Lake Worth Hines, T. R., Box 397, Tampa Hodnett, J. Victor, Box 958, Winter Haven Holcomb, E. D., Jr., Winter Haven Holden, B. Heath, Rt. No. 2, Box 486, Homestead Holtsberg, Harold, 132 N. 12th St., Ft. Pierce Holzcker, Richard, Babson Park Hope, M. E., 513 W. Magnolia Ave., Dade City Hopkins. E. F., Citrus Exp. Sta., Lake Alfred Horton, Mrs. Wm. H., Haines City Howard, Frank L., Box 996, Winter Haven Huff, Norman V., Box 5, Winter Haven Huggart, Richard, Box 442, Bartow Hughes Seed Store, 116 S. Miami Ave., Miami 36 Hughes, W. H., Box 287, Elsa, Texas Hundertmark, B. W., Clewiston Hunter, George J ., Orlando Livestock Co., Deer Park Hunter, William P., 1039 W. Cypress St., Gainesville Huppe!, J. B., Windermere Husmann, Dr. W., 646 Seminole Drive, Winter Park Hutchinson, J. H., Rt. No. 1, Box 139K, Avon Park Idlewild Grove, Rt. No. 4, Box 1080, Tampa Ingram, Dr. Esther M., 204 Professional Bldg., Winter Haven Jacobs, W. A., 317 S.E. Fifth Ave., Delray Beach Jal army Citrus Groves, Minneola James, Robert H., Box 635, Dunedin Jamison, F. S., University of Fla., Gainesville Jimenez, M. A., Minute Maid Corp., Plymouth Joffre, David C., 29 S. Court St., Orlando John's Plants, Seeds & Bulbs, c/o John Masek, Apopka Johnson, J. A., P. O. Box 501, Avon Park Johnson, R. S., 929 E. 10th St., Sarasota Johnson, Warren 0., Box 1058, Lakeland Jones, H. L., State Plant Board, Gainesville Jones, W. J., Di Giorgio Fruit Corp., Winter Haven Jordahn, A. C., Box 292 Coconut Grove, Miami 33 Jorgensen, M. C., Box 233, Ruskin Kanawha Groves, 209 Gates Bldg., Charleston, W. Va. Karst, Art, Box 1110, Orlando Kasper, P. E., P. 0. Box 906, Tampa Kazaros, Robert S., 1610 Delaney St., Orlando Keel, Darnell, 2706 Price Ave., Tampa 9 Keene, R. D., Box 338, Winter Garden Keil, P. F., 530 N. E. St., Raleigh, N. C. Kelbert, David G. A., Box 678, Manatee, Sta., Bradenton Kelly, Dr. Reba Allen, Fla. Southern College, Lakeland Kelsheimer, E. G., Box 678, Manatee Sta,, Bradenton Kempf, Mrs. E. J., King Grove, Eustis Kendall, Harold E., Box 868, Goulds Kent, L. C., Box 806, Orlando Kesterson, J. W., Citrus Exp. Sta,, Lake Alfred Kew, Theo. J., 1721 Westchester Ave., Winter Park Kime, Charles D., Box 232, Ft. Pierce King, John R., 1201 4th St., N.E., Winter Haven King, Percy M., Box 42, Quincy Kingsbury, Miss Joan, Box 124, Lake Wales Kirkley, AI. G., Box 1112, Winter Haven Knox, Jean H., P. 0. Box 898, Haines City Kransch, Kenneth, 1000 Widensor Bldg., Philadelphia 7, Pa. Krome, Isabelle B., Miami Krome, William H., Box 596, Homestead Krome, Mrs. William J., Box 596, Homestead Kuitert, L. C., Exp. Sta., Gainesville Ladeburg, C. F., Box 6085, West Palm Beach Lamb, Geo., Marianna Lamont, Henry, Rt. No. 2, Ft. Pierce Larson, L. J., Winter Haven Lawless, W. W., 1645-16th St. N.W., Winter Haven Lawrence, Fred P., 402 Newell Hall, Univ. of Fla., Gainesville Lee, W, S., Box 176," Mims Leibovit, Arthur B., Winter Rose Apts., 403 N. Olive Ave., West Palm Beach Leonard, Chester D., 631 "H" N.W., Winter Haven Lewis, D. E., Box 1171, McAllen, Texas Lewis, H. F., Terra Ceia Link, O. D., Davie Rd., Ft. Lauderdale Lippincott, Mrs, W. A., P. 0. Box 997, Stuart Lipscomb, S. F., Bartow Little, C. S ., Odessa Little, H. W., 311 Horticulture Bldg., Univ. of Florida, Gainesville Livingston, Bert, 3024 Fair Oaks Ave., Tampa

PAGE 16

FLORIDA STATE HORTICULTURAL SOCIETY, 1950 XVII Lock et t , Nonvood A., Box 358, Leesburg Logan. J. H., County Agent, Box 540, Cl ea rwater Long, Wallace T . , Box 1198, Ft. Pierce Lord, E. L., Sub-Tropical Gardening, Ft . Myers Lorz, A. P., Fla. Agr. Exp. Sta., Gainesville Loucks, K. W., Lake Allred Lucas, G. H., Penins;,lar Fertilizer \Vorks , Box 3272, Tampa Lundb e rg, Ernest C., 1319 N.\V , Second Ave., Gainesville Lyle, J. I., Rt. No. 5, Box 888, Orlando Lynch, S. John, Rt. No. 1, Box 185B, Homestead MacDowell, Louis G., Box 1720, Lakeland Mackay, Mrs. R. F. B., Lake Alfred Madsen, H. S ., Lake Morten Apts., Lakeland Magie, Robert 0., 2906 Ninth Ave., W., Bradenton Malcolm, J, L., Rt. No. 2, Box 508, Homestead Manfre, Stephen J., 742 Lib e rty Ave., Cor. Essex St,, Brooklyn, N. Y. Marler, Buck, Fla. Fertilizer Co . , Lakeland Marlow, Wm . L., Box 1709 , Jacksonville Martin, Chas. H ., 802 E. Hamilton, Tampa Martsolf, J. D., Ocklawa Masek, John, Apopka Masten, Harold R., 151 Grace Terrace , Palm Beach l'vfathias, A. F., Box 183, Lake Hamilton ~1athias, F. C., Haines City Citn1s Grove Association, Haines City Maulhardt, Richard F., Rt . No . 1, Box 579, Camarillo , California Maxcy Fertilizers , Inc., E . R. Johnston, Frostproof Maxwell, Lewis S., Jackson Grain Co., Tampa 1 Maxwell & Anderson, San Mateo Mayeux, Herman S., Fla. Agr. Supply Co., Jacksonville Mayfield, Harry, 608 Easton , Lakeland Mayo , Nat, Ocala Mayo, The Honorable Nathan, Commissioner of Agr., Tallahassee Meckstroth, Dr. G . A., 415 N. Parramore, Orlando Mell, James R., 409 Candl e r Bldg., Atlanta, Ga. Menninger, Edwin A., Stuart Mercer M. T., Box 181, Coral Gables 34. Merrill, G. P., State Plant Board, Gainesville Merrill, W. H., State Plant Board, Gainesville Meserole, Mrs. George, San Mateo Michael, Joe E., Box 324, Palmetto Miller, C. E., 2598 Taylor St., San Francisco, Calif. Miller, E. W., P. O. Box 1435, Clearwater Miller, H. N., Dept . of Plant Pathology, Gainesville Miller, Leon , Rt. No . 6, Orlando Miller , Ralph L., Plymouth Citrus Grow e rs Association, Plymouth Miner, James T., P. 0. Box 341, Boynton B e ach Minute Maid Corp., Plymouth Mooers, Neal D., Babson Park Moore, Clarence H., Drawer 31, Winter Haven Mooty, A. F., Box 814, Winter Haven Morgan, Charles E., 1116 E. Livingston, Orbndo Morrell, P. C., 431 -E. Central Ave., Eola Plaza, Apt. 402, Orlando Morrow, William B., 1525 Sunset PlacP , Ft. Myers Morse, John, 729 Indian Riv e r Dr., Ft . Pierce Morton, J. F., 113 Mendoza, Coral Gables Mounts, M. U., County Agent, Box 70, W, Palm Beach Mowry, Harold, 2455 University Station, Gainesville Mullen, Harris, Fla , Grower Magazine, Inc., Tampa Mullinax, H. S., 315 Ave. B, N.E., Wint e r Haven Mustard , Margaret J ., Box 1015, Univ. of Miami, Miami Myers, C. J., General Delivery, Tallahassee Myers, Forrest E., Fla. Agr, Extension Service, Gainesville McBrid e, J. N., Union Sta., Bldg., Savannah, Ga. McCallum, J. B., Hastings McClanahan, H. S., State Plant Board, Gainesville McClure, George G., Lake Alfr ed l\IcCoy, Sinclair, 29th Floor, 20 N. Wacker . Dr ., Chicago 6, Ill . McCubbin, E. N., Potato Laboratory, Hastings ).l.fcDonald Division, Clinton Foods, Inc., P. O. Box 500, Auburndale McDuff, 0. R., Adams Packin~ Assn . , Inc., Auburndale McIntyre, A. E. C., Box 112, Homestead McKinnis, Ronald B., Brown Citrus Machinery Corp., 401 S. Greenleaf Ave., Whittier, California McPeck, John K., 328 S. Lakevi ew Dr., Sebring Nabors, C . M . , 1007 Wallace S. Bldg . , Tampa Nann ey , W. C., 2419 7th Ave., \V., Bradenton National Fertilizer Assn., 616 Continental Bldg., Washington 5, D. C. Neal, J. H., Hercules Powder Co., 134 Peach Tree St., N.W., Atlanta, Ga. Neff, Frank, 605 W. Warren, Tampa Nelson, Roy 0., Univ. of Miami , Box 1015, S. Miami Nettles, Victor F., Hort. Dept. Agr. Exp. Sta . , Gainesville New Smyrna Beach Garden Club, New Smyrna Beach Newins, Harold S., Director School of Forestry, Univ. of Fla ., Gainesville Nicholson, Joe, 702 McLendon St., Plant City Nikitin, A. A., Tennessee Corp. Res. Labs . , Box 89, College Park, Ga. Noble, C . V., 1460 N . Brove St., Gainesvill <' Norman, Gerald G., 2170 Fawoalt Road, Winter Park Norris, R. E., County Agent, Tavares O'Byrne, Frank M., Jr., 630 E. 38th St ., Hial ea h Ochse, Dr . J. J., Univ. Branch Box 156, Miami Oglesby, R. M., Box 180, Bartow O'Kelley, E. B., ACL Railroad Co., Jacksonville Olsen, H., Davenport O'Shea, Col. Kevin, 2911 Riverview Blvd ., Bradenton Palmer , Charles, 340 E. Lemon St., Bartow Palmer , J. M., Box 936, Lutz Pan American Metal Products Co., Inc., 401 N.W. 71st St., Miami Paquin, W. E ., Box 519, Winter Garden Parker, Coleman H ., Box 919, Winter Haven Parris, G. K., Watermelon Laboratory, Leesburg Patrick, Dr. Roger, P. 0. Box 403, Winter Haven Pedersen, W. C., Lake Wales Peebles, T . A., Box 877 , . Vero Beach Pennsylvania Salt Manufacturing Co., 1000 Widener Bldg., Philadelphia 7, Pa. Perkins, Bernard C., Sebring Pfister, Mrs. H. C., Box 692, Winter Haven Phelps, George W,, Stauffer Chemical Co. Winter Haven Pinkerton, David W. , City Point Pipkin, W. A., Safety Harbor Plaquemines Parish _ Exp. Sta., Louisiana Stat e Univ., Att: Mr. Ralph T. Brown, Superintendent, Diamond, La. Platts, : Nor . man G., Rt. No. 2, Box 242, Ft. Pierce

PAGE 17

XVIII FLORIDA STATE HORTICULTURAL SOCIETY, 1930 Pollard, W. R., Box 23, Brndenton Potash Co. of America, 50 Broadway, New York, N. Y. Pratt, Robert M., Citrus Exp. Sta., Lake Alfred Price, R. C., 2826 Oak St., Jacksonville Pride, Richard E., Frostproof Princess Grove , Box 227, Lake \Vales Pulley, George, P. 0. Box 13, Winter Haven Rainey, B. T., Dolomite Products, Ocala Ramsey, Vernon E., P. 0. Box 7, Suffolk, Va. Rawls, Glenn, Plymouth Reark, J. B., Univ. of Miami, Miami Reasoner, Egbert S . , Box 828, Bradenton Reed, H. M., Fla. Agr. Exp. Sta., Gainesville Reints, J. E., Winter Haven Reitz, Dr. J. Wayne, Provost of Agr., Univ. of Fla., Gainesville Reitz, H. J., Citrus Exp. Sta., Lake Alfred Reuther, Dr. Walter, 415 N. Parramore St., Orlando Reynolds, B. T., Auburndale Rich, Frank H . , Box 130, Winter Haven Richborn, J. H., Box 1401, Lakeland Riegel, Mark, Experiment, Ga. Riester, D. W., American Can Co., Box 1732, Tampa Roberts, A. S., Box 694, Ocala Roberts, Pasco, Box 728, St. Petersburg Robinson, H. B., Box 2266, Miami 13 Rock, Fairfield, Homestead Rogers, H. S., Box 823, Winter Haven Rogers, J. T., P. 0. Box 448, Plant City Rollins, C. F ., Clearwater Root, C. A., Winter Haven Roper, R. R., Winter Garden Rosenberger, Stanley, Agr. Ext. Service, Gainesville Ross, Stuart W., Lake Wales Rounds, Marvin B., 224 N. Michigan Ave., Glendora, California Rouse, A. H., Citrus Exp. Sta., Lake Alfred Rowe, W. M., 1007 Wallace S. Bldg., Tampa Ruehle, Dr. George D., P. 0. Box 604, Homestead Rumpsa, Paul L., Drawer 608, Avon Park Ruprecht, R. W., Box 327, Sanford Ruskin Vegetable Coop ., Ruskin Russell, J. C., P. 0. Box 177, Sanford Sahlberg, Nils, Box 252 C-19, Orlando Sample, J. M., Box 113, Lake Hamilton Sampson, R. H., Box 7, Mango Saurman, A. Vernon, Box 686, Clearwater Savage, Clifford B., 416 El Prado Ave., W. Palm Beach Savage, Zack, Agr. Exp. Sta., Gainesville Sawyer, David P., Box 1266, Vero Beach Schaaf, Harold H., Box 349, David City, Nebraska Schrader, Otto Lyra, Rua Santa Clara 256, Rio de Janeiro, Brazil Schock, W. V., P. 0. Box 462, Winter Haven Schulz, W. H., Winter Haven Scott, A. G., Box 651, Winter Haven Sealey, J. H., Box 124, Arcadia Seims, Mrs. Roy E., Box 663, Avon Park Sexton, Mrs. Eva., Sexton Groves, Winter Haven Sexton, . W. E., Vero Beach Seymour, Frank, Box 1327, Lakeland Sharpe, R. H., Fla. Agr. Exp. Sta., Gainesville Shinn, Charles M., Lake Alfred Shoupe, Arthur H., 1130 Fifteenth Ave., N., Lake Worth Showalter, R. K., Agr. Exp. Sta., Gainesville Siamonton, W. A., Citrus Exp. Sta., Lake Alfred Silver Lake Estates, Ltd., Leesburg Simmons, Paul U . , P. 0. Box 260, \Vinter Haven Singl e ton, Gray, 125 E. Palm Drive, Lakeland Sites, J. W., Citrus Exp. Sta., Lake Alfred Sklute, Morris, 1658 2lst Ave . , N., St. Prtershur!( Smiley, Nixon, Homestead Smith, Al G., Box 88, Palmetto Smith, F. B., Agr. Exp. Sta., Gainesville Smith, J. Lee, Rox 6, Homestead Smith, Laurin G., Tennessee Corp., 619-27 Grant Bldg.; Atlanta 1, Ga. Smith, Paul , 415 N. Parrnmore. St., Orlando Snell, R. R., Avon Park Snodgrass, William, Rt. No. 1, . Clermont Soil Science Foundation, Lakeland Soowal, J. M., 822 Arlington Ave., Orlando Soule, M. J., Jr., Univ. of Miami, Box 1015, S. Miami South Florida Motor Co., Sehrin!( Souviron , Max J., 2845 S.W. 22nd Terrace, Miami 34 Spalding, A., Rt . No. 2; Box 66, DeLand Speer, H. L., Box 326, Belle Glade Spencer, Dr. Ernest L., Veg. Crops Lah., Box 678, Manatee Sta., Bradenton Spencer, Herbert, U.S.D.A., Box 112, Ft. Pierce Spencer, T. C., Haines City Sprott, Kingswood, Lake Wales Stabler, D. ' K,, Winter Haven Stahl, Dr. A. L., Univ. of ~,fiami, South C.Ltmpns, Miami Stauffer Cemical Co., Box "K'", Apopka Sterling, H. 0., Box 176, Bartow Stevens, H. E., Amherst Apts., Orlando Stewart, Tom B., Box 6, DeLand Stirling, Walter, Rt. No. 1, Ft. Lauderdale Stoddard, David L., Room 205, Walcaid Bldg., Bradenton Stoner, Dr. Warren H .. Everglades Exp. Sta., Belle Glade Sturrock, David, 1021 Camellia Rd., W. Palm Beach Sturrock, Thomas T., 1021 Camellia Rd., West Palm Beach Suit, R. F., Citrus Exp. Sta., Lake Alfred Summerfield Nursery Co., Weirsdale Sutton, Cliff, 806 Lucerne Terrace, Orlando Swank, George, Central Fla. Exp. Sta., Sanford Swann, Thomas, Winter Haven Swartsel, J. A., Reints Apt., Apt. No. 1, 1st St. & Lake Silver, N.W., Winter Haven Swartsel, R. V., Lake Gem Taber, Geo. L., Jr., Glen St. Mary Nurseries Co., Glen St. Mary Tait, W. L., P. 0. Box 69,'5, Winter Haven Talbert, Dale, Vero Beach Taylor, Mrs. Bright, P. 0. Box 623, Ocala Taylor, J. J., State Chemist, Tallahassee Thomas, W. W., NACO Fertilizer Co., 2005 Lake Sue Dr., Orlando Thompson, Robert, Box 1231, Orlando Thompson, W. L., Box 1074, Lake Alfred Thornton, R. P., Box 2880, Tampa Thullbery, H. A., Lake Wales Thursby; Isabelle S., Box 68, Orange City Tiedtke, John, Clewiston Tilden, Fred; Winter Garden Timmons, Mrs. Ruth, Belle Glade Tindal; George, Ft. Pierce Cooperative, Ft. Pierce Tisdale, W. B., Agr. Exp. Sta., Gainesville

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FLORIDA STATE HORTICULTURAL SOCIETY, 1950 XIX Toffaleti, James P., Box 1231, Orlando Tomasello, Rudolph P., 911 Bignonia Rd., West Palm Beach Tower, John B., Rt. No. 1, Box 60, Homestead Townsend, G. R., Box 356, Belle Glade Tropical Agriculture, S. A., C a lle Ermita S/N, La Habana, Cuba True, H. H., 438 N . E. 8th Ave., Ft. Lauderdale Twenhofel, Dr. W. W . , P. 0 . Box 1231, Orlando United Growers & Shippers Assn., Orlando United Growers and Shippers Assn., 14 E. Hamilton St., Tampa Van Clief, W. C., Winter Haven Van Horn, M. C., 4517 Beach Tree Circle E., Jacksonville Van Kirk, J. C., RFD No. 1, Ft. Lauderdale Veldhuis, M. K., U. S. Citrus Production Station, Winter Haven Volk, Gaylord M., Dept. of Soils, Exp. Sta., Gainesville Voorhees, R. K., Box 232, Ft . Pierce Wagner, W. E., Geary Chemical Corp., Empire State Bldg., New York, N. Y . Waldron, Max, Rt. No. 1, Ft. Lauderdale Walker, Marvin H., 720 Lakeshore Blvd., Lake Wales Walker, Seth S., 3002 Wav e rly Ave., Tampa 9 Wallace, Geo. R., Lake Park Walter, J. M., Vegetable Crops Lab., Box 678, Manatee Sta. , Bradenton Wander, Dr . I. W . , Citrus Exp . Sta., Lake Alfred Ward, W. F., Box 177, Avon Park Ware, C. E., 1411 N. Ft. Harrison, Cleanvater Warren, Alfred, Rt. No. 1, Box 212, Vero Beach Watson, E. R., Oakadia Groves, Nursery Rd., Clearwater Watson, J. D., 804 S. Dargan, Florence, S. C. Weetman, L. M., U. S. Sugar Corp., Clewiston Wenzel, Dr. F. W., Citrus Experiment Station, Lake Alfred West, Erdman, 101 Newell Hall, Univ. of Fla., Gainesville West Coast Fertilizer Co., 1601-3lst St., Tampa Westgate, P. J., Central Fla. Exp. Sta., Sanford White, Alec, 5506 Seminole Ave., Tampa White, J . F., Julius Hyman Co ., Denver, Colorado Whitmore, Al H., Box 2111, Orlando Williams, H. A., Kilgore Seed Co., Ocala Williams, Lyons H., Jr., F. H. Woodruff & Sons, Inc., Box 815, Coral Gables Williams ,Miss -Myra G., Rockledge Williams, Ralph E., 1134 N. Yates Ave., Orlando Wilson, A. E., Citrus Experiment Station, Lake Alfred Wilson, Don H., Bartow Wilson, E. H., 91 Norman Bridge Rd . , Montgomery, Ala. Wilson, Gaines R., 3853 Little Ave., Coconut Grove Wilson, H. L., Box 156, Bartow Wilson, John R., 1036 Francis St., Box 6206, West Palm Beach Wilson, J. W., Central Fla. Exp. Sta., Sanford Wilson, Leo H., Box 48, Bradenton Wilson, Robert A., Box 25, Hobe Sound Wilson, Robert G., Rt, No. 2, Box 594, Miami Winston, J. R., 415 N. Parramore, Orlando Winter Garden Ornamental Nursery, Inc., Box 428, Winter Garden Wirt, Erle L., Jr., Babson Park Wolf, Emil A., Ever g lades Exp. Station, Bell e Glade Wolf, Frederick A ., Duke University, Durham, N. C . Wolfe, Dr. H. S., Head Dept. of Hort ., Univ . of Fla., Gainesville Wolfenbarger, D. 0., Rt. No. 2, Box 508, Hom es tead Woods, V. E., Box 734, Davenport Yonge, J. R ., Box 788, Ft. Pierc e Young, Dr. C. T., Box 948, Plant City Young, T, W., American Fruit Growers, Ft. Pierce Ziegler, Louis W., College of Agr., Univ. of Fla . , Gainesville Zill, L. H., 813 N. Federal Highway , Delray Be~~h Zoffay, John C., Frostproof

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xx FLORIDA STATE HORTICULTURAL SOCIETY, 1950 PROCEEDINGS OF THE FLORIDA STAT~ HORTICULTURAL SOCIETY, 1950 VOLUME LXIII PRINTED 1951 CONTENTS Officers for 1950 .................................. . ....................................................................... IV Officers for 1951 ........................................................................ . .... . ............................ V Constitution and By-Laws .. . .......... . . . ...... . ...... . ....................... . .................................. VII Award of Honorary Memberships ................................................... . ....................... , IX List of Members ................................ , ....................................................... . ... . ..... .. ...... XI President's Annual Address, Leo H. Wilson, Bradenton ........ ,............................. 1. Partial Mobilization and the Florida Fruit and Vegetable Industry, Dr. J. Wayne Reitz, Provost for Agriculture, University of Florida, Gaines: ville .......................... ......... .. ............... . .................... . ............................................. 3 CITRUS SECTION The Effect of 2,4-D on Pre-Harvest Drop of Citrus Fruit Under Florida Conditions, F. E. Gardner, Philip C. Reece and George E. Horanic, U. S. Department of Agriculture, Orlando.................................................. 7 The Chemical Composition of Irrigation Water Used in Citrus Groves, I. W. Wander and H.J. Reitz, Citrus Experiment Station, Lake Alfred 11 Ground Water Resources of Florida, Herman Gunter, Florida Geological Survey, Tallahassee ................................... . ................................ . ..................... 17 Portable Irrigation on the Ridge, Morton Howell, Waverly....... . ............. . ...... . ... 26 The Response of Young Valencia Orange Trees to Differential Boron Supply in Sand Culture, Paul F. Smith and Walter Reuther, U. S. Department of Agriculture, Orlando ..................... . ....... .. .. ..... .................. ....... ............... ... ... 29 Rio Grande Gummosis, Its Occurrence in Florida Citrus, J. F. L. Childs, U. S. Department of Agriculture, Orlando.......... . ...... . .................................. 32 Present Status of Spreading Decline, R. F. Suit and H. W. Ford, Citrus Experiment Station, Lake Alfred............................................... . ...... .......... .... 36 The Purple Mite and Its Control, W. L. Thompson and J. T. Griffiths, Jr., Citrus Experiment Station, Lake Alfred........................................................ 42 Florida's Stake in Plant Quarantine Enforcement, Avery S. Hoyt, Chief, Bureau of Entomology and Plant Quarantine, Washington, D. C............. 48 Possibilities for the Use of Concentrated Sprays on Citrus in Florida, James T. Griffiths, C.R. Stearns, Jr., and W. L. Thompson, Citrus Experiment Station, Lake Alfred...... . ..................................................................................... 53

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FLOIUDA STATE HOHTICULTURAL SOCIETY, 1950 The Effect of Variable Potash Fertilization on the Quality and Production of Duncan Grapefruit, John W. Sites, Citrus Experiment Station, Lake XXI Alfred ... .................... .. ........................ ... . . .................................. .. .................... . .... 60 Panel on Parathion, Howard A. Thullbery, Lake Wales . . . .................. . ............... . 68 VEG ET ABLE SECTION Control of Late Blight and Gray Leaf Spot of Tomatoes with New Fungi cides, Robert A. Conover, Florida Agricultural Experiment Stations, Sub-Tropical Experiment Station, Homestead ............ 89 Fertilizer-Insecticide Combination for Armyworm, Mole-Cricket and Wire worm Control, D. 0. Wolfenbarger, Florida Agricultural Experiment Stations, Sub-Tropical Experiment Station, Homestead, and E. G. Kelsheimer, Florida Agricultural Experiment Stations, Vegetable Crops Laboratory, Bradenton . . . .... ..... ............ . ............................... .. .. .... ...................... 93 Toxic Insecticide Residues of Vegetables, J. W. Wilson, Florida Agricul tural Experiment Stations, Central Florida Experiment Station, Sanford ..... .. . ....... ..... .... . . ..... . ........... ... .... ............. ....... . . . . .... ... . .. . . . ..... . ................... 95 Processing and Labeling Pesticides, M. C. Van Horn, Jacksonville................ 99 The Role of the Regional Vegetable Breeding Laboratory in Breeding and Testing New Vegetable Varieties, S. H. Yarnell, U. S. Regional Vegetable Breeding Laboratory, Charleston, South Carolina ........ . ............ ..... .. 102 New Vegetable Varieties for Florida, David G. A. Kelbert, Florida Agri cultural Experiment Stations, Vegetable Crops Laboratory, Bradenton 108 Effect of Low Nitrate Nitrogen on Growth of Potatoes, Gaylord M. Volk and Nathan Gammon, Jr. , Florida Agricultural Experiment Station, Gainesville .... .. ............... . .......... ... .. .. . . .......... .. .................. . .......................... . .. .. . .. 112 Effects of Soluble Soil Salts on Vegetable Production at Sanford, Philip J. Westgate, Florida Agricultural Experiment Stations, Central Florida Experiment Station, Sanford ............... .. ...... . ............. . ................ , ...... ....... .... . . 116 A Nematode Attacking Strawberry Roots, A. N. Brooks, Strawberry Labora tory, Plant City, and J. R. Christie, U. S . Department of Agriculture, Sanford .......................... ..... .... . ........ .. ......... . .. ... ................................ . ........... ...... . 123 Nitrogen Transformation in Seedbeds as Affected by Nematocidal Treat ment, Ernest L. Spencer and Amegda Jack, Florida Agricultural Experiment Stations, Vegetable Crops Laboratory, Bradenton ...................... 125 Graywall of Tomatoes, Warren N. Stoner, Florida Agricultural Experiment Stations, Everglades Experiment Station, Belle Glade ........................... . . ... 129 Quality of Florida Potatoes and Some of the Factors Affecting Quality, R. E. L. Greene, Florida Agricultural Experiment Station, Gainesville 136 Mulching Vegetable Crops with Aluminum Foil, Donald S . Burgis, Florida Agricultural Experiment Stations, Vegetable Crops Laboratory, Bradenton ...................... ......... . .. ... ... .. ............ ..... ............................ .. ............ ....... 141 Transitory Effects of 2,4-D on the Watermelon Plant When Absorbed Through the Roots, Clyde C. Helms, Jr. and G. K. Parris, Florida Agri cultural Experiment Stations, Watermelon and Grape Investigations Laboratory, Leesburg ......................................... ... ............................................ 144

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XXII FLORIDA STATE HORTICULTURAL SOCIETY, 1950 PROCESSING SECTION Comparison of Plating Media U s ed for the Estimation of Microorganisms in Citrus Juice s , E. C. Hill a nd L . W. Faville, Citrus Experiment Station, Lake Alfred ---------------------------146 Relative Efficiencie s of Sever a l Liquid Presumptive Media Used in the Microbiological Examination of Citrus Juices , L. W. Faville and E. C. Hill, Citrus Experiment Station, Lake Alfred--------------150 Storage Changes in Citrus Mol a s s es, R. Hendrickson and J. W. Kesterson, Citrus Experiment Station, L a ke Alfred _ __ -------------154 An Index of Pasteurization of Citru s Juices by a R a pid Method of Testing for Residual Enzyme Activity, Theo. J. Kew and M. K. Veldhui s, U. S. Citrus Products Station , Winter Hav e n _ _ __ _ _ _ ____ ------------------------162 Storage Changes in Frozen Conc e ntrated Citru s Juices-Preliminary Re port, Edwin L. Moore, Richard L. Huggart, and Elmer C. Hill, Citrus Experiment St a tion, Lake Alfred ------------------------165 A Method for Estim a ting Soluble Solids in Dried Citrus Pulp, Owen W. Bissett , U. S. Citrus Product s Station , Winter Haven-------174 ORNAMENT AL SECTION The Genus Allamanda in Florida, Egbert S. Re a soner, Brad e nton __ ______ _ _ _ _ _ _ __ . _ 179 Some Ornamental Trees and Shrub s Native to South Florida, Geo . D . Ruehle, Florida Agricultur a l Experiment Station s, Sub Tropical Ex periment Station, Homeste a d -----------------------------------180 The American Hibiscus Society, Norman A. Re as oner, Bradenton __ __ _ _____ _ ___ .... 183 Interesting Uses of Woody Plant s , George L . Taber , Glen S t. Mary _ _ _ _ _ ___ .. . . 187 Soil Sterilization, H. N. Miller, Florida Agricultural Experiment Station, Gainesville ---------------------------------------------------190 Greenhouse Foliage Plants in Florida, Peter Pearson, Plymouth _ _ _ _ ______ ______ __ _ _ 192 The Daylily in Florida, Wyndh a m Hayward, Winter Park _ _____ _ _ ____ __ __ ___ _ ___ __ _ _ ; __ _ 194 Horticultural Rese a rch with C a mellias, G. H. Blackm o n, Florida Agricultural Experiment Station, Gainesville ___ ___ _ __ _ _ __ _ _ ___ ______ _ __ _ _ __ _ _ _ _ _______ _ _ _ __ ___ _ __ _ 19 8 Notes on Camellia Diseases, Erdman West, Florida Agricultural Experi ment Station, Gainesville -----200 Factors Affecting the Keeping Quality of Cut Flowers, R. D . Dickey, Florida Agricultural Experiment Station, Gainesville _ _ ------_ 203 Insect Control on Ornamental Plants of the Home Garden, L. C. Kuitert , Florida Agricultural Experiment Station, Gainesville _ _ _ -----------206 KROME MEMORIAL INSTITUTE Fairchild Tropical Garden, Charles H. Crandon, Coconut Grove __ ______ _ __ ____ _ _ _ _ . 209 Radio Garden Club s , Pasco Roberts, St. Petersburg ___ _ ___ --------------213 We Make A Men's Garden Club Tick, Bert Livingston, Tampa--------215

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FLORIDA STATE HORTICULTURAL SOCIETY, 1950 XXIII Fruit Gift Packages, Edward A. Ash, Homestead .................................................. 217 Observations of Some of the Newer Mangos During the Year of 1950, L. H. Zill, Delray Beach ........................................ ... ...... ............. .. ................. ..... .. . .. ... 219 Monthly Meetings on Tropical and Sub-Tropical Fruits, M. U. Mounts, West Palm Beach ....... ... .................................... . ........................ ....... ................ 220 Marketing Fresh Lychees, DeWitt Eaton, Sarasota . ...................... ........... .......... 222 A Survey of Diseases Lethal to Tahiti (Persian) . Limes in Dade County, C. M. Gates and M. J. Soule, Jr., University of Miami, Coral Gables .... 225 Packaging and Storage of Persian Limes, Margaret J. Mustard, University of Miami, Coral Gables ...................................................................................... 228 Studies of Stylar End Rot of Tahiti Limes, Robert A. Conover, Florida Agricultural Experiment Stations, Sub-Tropical Experiment Station, Homestead ............................................................................................................ 236 Twenty Years After, H. S. Wolfe, College of Agriculture, University of Florida, Gainesville ...................................................................... , ................... 240 Tropical and Sub-Tropical Fruits in Pinellas County, C. E. Ware, Clearwater .............................................................................. : ..................................... 245 The Future of Tropical and Sub-Tropical Fruits in Florida, E. V. Faircloth, West Palm Beach ................................................. , .............................................. 247 The Propagation of Sub-Tropical Plants by Cuttings, A Progress Report, J. J. Ochse and J. B. Reark, University of Miami, Coral Gables . ...... . ...... 248 Weed Control Studies Around Young Avocado Trees, Roy W. Harkness, Florida Agricultural Experiment Stations, Sub-Tropical Experiment Station, Homestead .................... ... .............................................. .... ................... 251 The Introduction into the United States and the Culture of Eleocharis Dulcis, The 'Matai' of China, G. Weidman Groff, Lingnan Plant Exchange, Laurel ..................................................................................... . ........ . ..... 262 Additional Notes on Mango Budding, S. John Lynch and Roy Nelson, University of Miami, Coral Gables ..... , ................ . ................................................. 266 ANNUAL REPORTS Report of Executive Committee ................................................................................ 269 Report of Treasurer .................................................................................................... 270 General Business Meeting of Society, Winter Haven, Oct. 31, and Nov. 2, 1950 ................................................ . .. .... .. ..... ......... .............. 271 Resolutions .................................................................................................................. 271 Necrology Committee ................................................................... . . ...... .... ................. 272

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PRESIDENT'S ADDRESS LEO H. WILSON Bradenton It is with keen pleasure I welcome the members and friends of this, the sixty third session of the Florida State Horti cultural Society. We have experienced many startling events since our meeting one year ago in Tampa. Increased re turns have been received for horticultural and agricultural products. We have been saddened by the loss of friends and the ravages of war. We look to the future with hopes for peace and security. The 1949 proceedings of the sixty sec ond session of the Florida State Horticul tural Society,. relates the passing of the late Frank Stirling of Davie, Florida, immediate past President of the Society. Every member I am sure joins me in pay ing tribute to one of Florida's leading Horticulturists. Frank was a loyal mem ber, and his going has been a great loss to the horticultural interests of Florida. The Korean war, now coming to a close, has taken the lives of thousands of our American men. May we pay homage to the gallant fighting of our soldiers who paid the supreme sacrifice, and those wounded and missing in action. The United States, together with other U.N. forces have about won this war. My humble prayer is we will win a lasting peace. The so-called "Florida Hurricanes" have been a dime a dozen this season. We have experienced ten hurricanes with two hits on Florida. The Gulf of Mexico blow that struck Cedar Key, did a tre mendous damage to this West Coast town. The second hurricane struck in the Miami, Hollywood, Okeechobee, In dian River Section. An estimate of $15,000,000 dollar damage has been re ported. Florida's East Coast Agricul tural interest suffered heavy losses . The damage to the citrus crop from the lower East Coast, extending North through Eastern Polk County, Orange and Lake Counties, estimate around 3,000,000 boxes of fruit, with grapefruit running 2,500,000 boxes and all other citrus fruits 500,000 boxes. These figures are subject to change as more damage shows up, especially the heavy drop that occurs from bruises and thorn injury. Florida's agricultural interest is con tinually being subjected to the introduc tion and attack by foreign insect pest and diseases. The dreaded South Ameri can disease known as Tristeza that has killed thousands of citrus trees in that country, may be present in the State of Louisiana. Two hundred trees in a planting on the Mississippi River Delta near New Orleans, have died recently from Tristeza, or some other form of tree decline. If not Tristeza, it could be Quick Decline. This form is taking a heavy tolCof citrus in California. Quick Decline might be termed a twin brother to Tristeza. The Florida Experiment Station, the United States Department of Agriculture and the Florida State Plant Board have visited this area. They are making a careful study on the type of decline in the New Orleans area. What can we do to safeguard Florida's citrus industry? It has often been pointed out that the State of Florida is in a vulnerable posi tion for the introduction of insects and diseases that could result in the destruc tion of many of Florida's important agri cultural crops. I can't urge the members of this group too strongly the necessity of cooperating with the State Plant Board and the Bureau of Entomology and Plant Quarantine, in their rigid en forcement to the letter of all existing laws and regulations. I am indeed glad to report how fortunate we are to have as a speaker at the General Session on Thursday morning, the Chief of the

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2 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Bureau of Entomology and Plant Quaran tine from the United States Department of Agriculture, the Honorable Avery S. Hoyt. Mr. Hoyt has proved a valuable friend to Florida. I am sure the Horti cultural Society membership joins me in expressing our sincere appreciation for his presence in the State and appearing on the program. The five sections that comprise the membership of the Florida Horticultural Society, namely: the Citrus section, the Vegetable section, the Processing section, the Ornamental section, and Krome Memorial section, have as a whole ex perienced a very fine year. The interest of these groups have been well cared for in many lines of research. Th?. Florida Experiment Station, which includes the Sub Experiment Stations, and the United States Department of Agriculture are conducting much needed research work. Florida appreciates this work and grow ers realize how much they have bene fited in the past from completed experi ments. May I throw out a challenge to the Society to lend every effort to keep this research and experiments now being conducted, driving ahead at full speed . We can keep these Institutions of service operating if we see the needed appropri ations are provided. Florida Citrus Mutual swung into op eration last season. This grower organi zation is to be congratulated for tying ninety percent of all citrus produced in the State, under one control. This may be considered the mammoth Co-op of growers for all times. The fact that so many Florida Citrus Growers, Shippers and Processors have come together on common grounds, to pool their interest for the betterment of the industry, has benefited the Florida Citrus Industry many millions of dollars. Its successful operation has gained recognition from other fruit producing areas of the world. The planting of citrus in Florida con tinues at a very rapid rate . Good prices for fresh fruit, canned and frozen con centrate has given impetus to the whole sale planting of thousands of acres in the last eight to ten years. At this point, may I throw out a word of warning to growers who contemplate new plantings. There will come a time when you may wish you had continued to pasture that marginal land you are now preparing to plant. With a high acre return on the investment, coupled with open winters, growers seem to forget the early precau tions given on the importance of "grove site selection." Are we ignoring the value of a good fertile soil, a soil well supplied with humus that maintains moisture? A well drained soil, and one adaptable to root stock and variety. Good elevation and air drainage is essen tial. In 1895, "Old Man Winter" struck hard, and drove the Citrus Industry South. If we exercise good judgment, and are cautious in selecting sites for grove plantings, we will by the law of averages, develop a profitable orchard. I believe the Florida State Horticul tural Society is the leading one of its kind in the world. We members should feel proud to be associated with such a wonderful organization. The program for this session consists of seventy three subjects, with as many or more speakers. A very fine program has been arranged, arid I appreciate the efforts made by the Vice Presidents of each Section in de veloping the programs we are to receive. When I say we have the finest Horti cultural Society in the world, there is a reason to back this statement. The exist ence of this Society just doesn't happen so. Hard work over these many years by its Officers have borne fruit. This particular year, it has been my privilege as your President, to observe the Officers in action. Nineteen members of the Executive Committee, (which includes all Officers) have held eight meetings during the year in Winter Haven. Please bear in mind not a single person receives a

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REl1Z: PARTIAL MOBILIZATION 3 penny for services rendered, and no ex penses allowed for travel. It required long trips from Miami in the South, Gainesville in the North, and from the East and West Coasts in attending these meetings. I have been greatly impressed with the fine spirit, loyalty to duty, and the untiring efforts of the officers and Executive Committee. Every member has performed his duties well. I have a very warm place in my heart for their splendid services . We have four officers that do the greater part of the work in an organiza tion of this kind. I especially wish to commend them for their fine accomplish ments this year. The Secretary, Dr. Ernest L. Spencer-Bradenton; the Treasurer, Mr. Lem P. Woods-Tampa; the Assistant Secretary, Mr. Ralph P. Thompson-Winter Haven; and the Editing Secretary, Mr. W. Lacy Tait Winter Haven. We owe these men a great deal of credit. I wish I had the space to enumerate every detail these Officers executed in bringing the Society up to its high standard. I am sure their reports will in part tell the story. I would like very much to see the mem bership of the Florida Horticultural Society increased. We should have sev eral thousand members. Florida is blessed by having a large number of intellectual growers. They would benefit the Society, and I am sure the Society would be of much value to them. We naturally trust everyone in attendance who are not members, will become mem bers during this session. Dues from the members pay for the proceedings. If dues come in early, the proceedings can be published on time. Every member can have a part in the successful operation of the Society. On behalf of the membership, may I express sincere appreciation to the city of Winter Haven for being host to the Florida State Horticultural Society. Our stay in your fair city will be a pleasant one. A very interesting and profitable meeting is assured. PARTIAL MOBILIZATION AND THE FLORIDA FRUIT AND VEGETABLE INDUSTRY' J. WAYNE REITZ, Provost University of Florida College of Agriculture Gainesville The Korean conflict has had and will have far-reaching effects on our national economy. It has resulted in much specu lation in recent months on what effects our increasing tempo of military prepa i;ation will have on our whole economy, including agriculture. Tonight I have chosen to join the speculators in order tpat we may consider some of the impli dations of the defense program on the f onomic position of Florida farmers, jnd on fru . it and vegetable proqU<;ers in . 1 articular. Any attempt to assess the possible effect of an enlargement of our defense effort, and the resultant expansion of our national budget onthe economic position of the Florida fruit and vegetable indus try, require s assumptions on the probable magnitude of the defense program and of prospects for peace. Let us consider two major assumptions. One assumption is that we are facing a period of at least a few years in which defense activity will continue at a much higher level than in previous post-war years. Present plans call for a military force of 3 mil lion men, or approximately twice as many as are now under arms. To maintain this force and provide the accompanying armaments, expenditures for 'i def~nse will

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4 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 probably reach an annual rate of at least 30 billion dollars for the fiscal year be ginning next July 1. This compares with estimated expenditures of about 20 bil lion dollars during the current fiscal year and approximately double the amount of the previous two years. A further as sumption is that there will be no armed conflict between major world powers. An open war between the United States and a country with the military might and productive capacity of Russia would change our defense policy from one of protection to one of survival, and, under such circumstances military expendi tures, manpower and material require ments would be strained to the limit more than ever before in our history. Assuming, however, that our defense requirements in terms of expenditures and manpower needs will be approxi mately as I have outlined, let us first think of meeting these requirements and their effects on our economy in general before assessing the probable effects on Florida fruit and vegetable producers. As we have already witnessed, the im mediate effects of additional outlays for defense purposes, assuming no other governmental action, is inflationary. The Korean conflict caught us operating at or near our peacetime productive capac ity. We had full employment for all practical purposes, and consumer incomes and, therefore, consumer demand soon reached an all-time high. These condi tions are quite different from those pre vailing in 1941 when another defense program was started. Then we had many idle resources. Under current circum stances, with no slack to be taken up, an expansion of our defense program has a doubly inflationary effect. First, in creased defense expenditures mean a larger volume of money in the hands of consumers and, therefore, an increased demand for consumer goods. Second, the . material requirements for an expanded defense program must be met partially at the expense of consumer goods, espe cially products of a durable nature, such as refrigerators, stoves, automobiles, radios, television sets, and housing. The full effect of each of these situations is yet to be felt. We are thus placed in a position where the buying power of con sumers is increasing while the products available for purchase is declining. Under such circumstances, prices will move up ward until a new equilibrium is reached between available supplies and existing purchasing power, unless the government exercises some anti-inflationary meas ures. Apprehension over the effect of insert ing a larger defense program into our already strained economy is not limited to economists and legislators, but is of vital concern to all. The dollar is in greater peril than during World War II or the immediate post-war years. Heroic measures will be needed to preserve its purchasing power. This accounts for the agitation for all out economic controls, and the broad control powers granted the President by Congress in the Defense Production Act of 1950. There is a tendency, however, to over estimate the effect of an expanded de fense program on the total supply of all goods, especially in view of the present level of business activity and the seem ingly imminent shortages in many lines of consumer goods. The current rate of business activity and heavy consumer buying is based in part on fear that pro duction of many lines of civilian goods will be interrupted when the defense program gets fully under way some months hence. To be sure, adjustments in production will be made involving a reduction in durable consumer goods, but bans on production seem rather remote. Recent estimates presented to Congress by the Defense Department indicate that the presently projected program of par tial mobilization will require about 4 percent of our annual steel production,

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REl1.l: PARTIAL MOBILIZATION .'5 and about 7 percent . of our productive capacity of copper, and about 14 percent of our aluminum at current production rates. Such demands do not suggest a sharp diversion of our productive capac ity into military channels or that civilians will face a serious problem of adjustment to lower consumption levels. However, when the full level of military expenditures is reached, the impact on prices will continue to be inflationary even though increased production of military goods will represent but a small part of the total national production now at an annual rate of some 270 billion dollars. Under prevailing economic conditions, and the impact of an expanded defense program, fruit and vegetable producers can look forward to a continued high level of demand for their products during the next few years. The demand for many fruits and vegetables will be bol stered by increased Government pur chases to meet the food requirements of a larger armed force. During the last war we found that the consumption levels of luxury type foods such as meats, dairy products, and many fruits and vegetables were considerably higher among service personnel than among civilians. As a result, we can expect the consumption rate of many of our products to increase with the expansion of our armed forces. The effects of increased military pur chases should be more noticeable in the canned and frozen food field, since a high proportion of such purchases will be in this form. Much more important than the in creased consumption of our armed forces is the indirect effect of anti inflationary controls on demand for fruits and vegetables and the great bulk of other farm products. We have noted already that increased production for defense purposes places more purchasing power in the . hands of consumers. For th~ economrin general, the inflationary effects thereof can be counteracted by credit restrictions, calling for higher down payments and shorter payment periods. Yet credit controls tend to in crease the demand for farm products. Such controls make it impossible for large numbers of consumers to obligate their future earnings through install ment buying. Thus, they are simply taken out of the market as buyers of dur able goods and housing. The result is that the housewife has more dollars avail able for buying food, particularly the so-called luxury items, such as meats, green and leafy vegetables, and fruit Jmces. However, it should be borne in mind that the full effects of such controls will not be noticeable for some months. Now let us turn to production problems arising from partial mobilization. There seems to be little reason to expect any pronounced production difficulties under the assumptions made. I have already indicated that the requirements of our basic metals for defense purposes will not be excessive. It does not appear at this time that there will be any serious short ages of farm machinery. Should short ages develop, the Government, no doubt, would hasten to assure adequate produc tion through allocating critical materials to specific industries. Fortunately, the quality and condition of machinery and equipment on Florida farms are excellent. Critical shortages of im1ecticide mate rials are not likely, although some sub stitution may have to be made for some chemicals which require large amounts of chlorine. Fertilizer supplies should be adequate to meet normal usage and production requirements. To be sure, nitrogen will be required to produce ammunition for training purposes and for stock-piling, but demands for such purposes should represent a comparative ly small proportion of our total output and should not be great enough to affect the supplies available for agricultural production, Furthermore, much of the

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6 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 great capacity for nitrogen production developed during the war years is not in use at the present time. Some manpower shortages will develop as a result of an increase of . one and . a half million men in the armed forces along with demands for labor in produc ing armaments. But such shortages should be felt least of all in the field of agriculture. While the effects of the draft or enlistments on available labor supplies will be equally distributed throughout the economy, the increased demand for civilian labor will be con fined largely to the industrial areas of the North. We should also bear in mind that a part of our defense production will be at the expense of goods for civilian consumption, and that the in crease in our labor requirements will be somewhat less than proportionate to the expansion of the defense program. Under such circumstances, and based on our previous assumptions, Florida fruit and vegetable producers should not face seri ous labor shortages. I might add, how ever, that as a precaution against a real emergency, steps should be taken to pro vide for labor-saving techniques and equipment. I mentioned the broad control powers granted the President in the Defense production Act passed in the recent ses sion of Congress. Failure to exercise these powers to the fullest has been the subject of much criticism. Discussion of controversial subjects often develops more heat than light, and this is no exception. The chief clamor has been for wage and price ceilings, and, if neces sary, consumer rationing. Price controls may make practical politics, but are al most certain to have an undesirable effect on our productive effort and on the defense program. In times of stress we are inclined to forget the real function of price in our capitalistic economy. We fail to remember that price is the one and only guide of the producer, that price is the means by which availabJe supplies of goods are apportioned among consumers, so that the amount _ :which people wish . to buy is just equal to that which people wish to sell. As yet, we have failed to find or devise a means of achieving the delicate balance that is inherent in the price mechanism on •. a free market. In attempting such operations, some prices are fixed too low so that production is discouraged and consumption is increased; the result: a virtual disappearance of the affected com modity from the market. On the other hand, some prices are fixed too high, so that consumption is discouraged while production is increased; and the result in this case: the accumulation of surplus supplies. Our experience with price controls during the last war, particularly on perishable agricultural products, indi cate that we cannot duplicate or replace the pricing mechanism; and that we cannot achieve a balance between produc tion and consumption without a free market price. This is not to say, however, that we should do nothing about the general level of prices. No responsible person can be complacent about the dangers of infla tion. We have means by which the general level of prices can be controlled without taking on the almost hopeless task of replacing the pricing mechanism with a price control program. If we earnestly desire to check in flationary tendencies we can do so by the Federal Government adopting proper fiscal policies. This can be done by the simple expedient of controlling the quan tity of money people have to spend through the use of credit restrictions or increased income taxes, preferably both. Direct credit restrictions, such as those currently in effect on durable goods and housing, reduce the level . of , effective demand for such ' products. If made in creasingly stringent, .. consUine1 : , buying power will . be redticed to the point of

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GARDNER, REECE AND HORANIC: PRE-HARVEST DHOP 7 bringing about price declines. Other effective curbs on credit can be accom plished through regulations imposed on the banking system, through the facili ties of the Federal Reserve System. The possibilities of increasing taxes to check inflationary pressure has been recognized by the present administration and the realities thereof will be apparent when the monthly pay check comes in tomorrow. Increased income taxes not only reduce consumer buying power, but avoid the inflationary effects of deficit financing through the media of Treasury bonds. Yet, as an anti-inflationary measure, taxation has the fundamental disadvantage of being extremely unpopu lar. As a result, it is difficult politically to increase the taxation rate to the extent necessary to affect consumer demand and in turn the general level of prices. It is doubtful, therefore, if we shall have the fortitude to put partial mobilization on a CITRUS pay-as-you-go basis, and consequently the net effect will be inflationary. To summarize, the over-all effect of partial mobilization on the Florida fruit and vegetable industry will be to provide a stronger demand for products than would otherwise exist. Production costs will increase, but no serious shortages are expected in materials and labor. There is nothing in the current or future situation to warrant price controls or consumer rationing. If they appear to be needed, the best method of handling is by controlling the general price level through tightening over-all credit con trols and increased taxation rather than by interfering with the pricing mechan ism. How far we shall go in credit controls or taxation I do not know, but of this I am sure; if we do the job which is now before us-as it should be done-our sacrifices are going to have to match our hopes and aspirations for peace. SECTION THE EFFECT OF 2, 4-D ON PRE-HARVEST DROP OF CITRUS FRUIT UNDER FLORIDA CONDITIONS F. E. GARDNER, PHILIP C. REECE AND GEORGE E. HORANIC Bureau of Plant Industry, Soils, and Agricultural Engineering, United States Department of Agriculture Orlando Pre-harvest drop of citrus fruit dur ing some seasons reaches a high per centage of the total crop in certain varieties. Midseason varieties, such as Pineapple and seedling sweet oranges, are generally considered the most prone to heavy pre-harvest dropping. Periods of warm, dry weather during the fall and winter months favor fruit shedding. Losses from this cause may constitute as much as one-third of the total crop and are rarely less than 15 percent . The Valencia variety is not considered such a bad dropper, and indeed fruits rarely fall in such large numbers within a short time as is frequently observed with Pineapple orange near the end of its maturity season. However, the drop extends over a much longer period in

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8 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 the case of Valencias, so that the total losses in this variety also may be very heavy. The rapid decay of grounded fruit and also the covering-up of such fruit from time to time by grove disking serves to hide from the grower the magnitude of the losses during a pro longed dropping period . Following the successful use of naph thaleneacetic acid and naphthalene acetamide to control pre-harvest drop of apples (3), it was reported by Gard ner in 1941 (1) that these compounds also could be used to materially lessen the drop of Pineapple oranges in Florida. However, the relatively high concentra tions required and the fact that the materials were not found to be effective applied later than November, made the discovery of doubtful practical value . More recently the findings of Stewart and his associates in California have shown that 2,4-D is much more potent in controlling the drop of citrus fruits and, as a result, its use is gaining wide acceptance in that State. Stewart and Klotz (4) sprayed Valencia orange trees in May with a 2,4-D derivative (die thanolammonium 2,4-dichlorophenoxy acetate) in concentrations of from 5 to 40 p.p.m. and reported a decrease in fruit drop, compared with the controls, of up to 55 percent at 40 p.p.m. On Marsh grapefruit Stewart and Parker ( 5 ) used the same compound in June in concentrations of 5, 25, 75, and 225 p.p.m and obtained nearly as good control with the two lower concentrations as with the higher ones; both of the latter caused rather severe foliage dam age. It should be noted that the sprays applied in May and June are just prior to harvest period of these varieties in California. The trees at this time ~vould be in a very active ' condition. This situation will be .referred to : lat~r, as it may have a bearing on the diver gent results secured in the studies here reported with sprays applied in the fall and winter months. 1948 Experiments Sprays of 2,4-D and several other hormone compounds were applied to Pineapple and Valencia oranges . . Trees were chosen for their comparable size and crop in blocks of s ix. Blocks were replicated ten times and within each block the following six treatments were applied to single-tree plots: (1) 2-methyl 4-bromophenoxyacetic acid; (2) 2methyl phenoxy alpha-butyric acid; (3) 2-methyl 4-chlorophenoxyacetic acid; (4) sodium salt of 2,4-D, all four mate rials being applied as sprays at concen trations of 20 p.p.m. of 2,4-D acid equivalent; (5) isopropyl ester of 2,4-D incorporated with dusting sulphur and used as a dust, also at the rate of 20 p.p.m. of 2,4-D; (6) control plots receiv ing no spray or dust. Sprays were applied on October 15 by a ground crew with conventional high pressure rig. Thorough coverage was TABLE L THE EFFECT OF SEVERAL HORMONE COMPOUNDS ON PRE-HARVEST DROP OF CITRUS. -Pre-harvest Drop in Percent of Total Crop Treatm e nts Applied October 15, 1948 Applied Valencia Cone, 20 p,p.m, Fr ee Acid Equiv. As Pineapple (+Splits) ( ~Splits) 2-meth. 4-chloro phenoxyacetic Spray 24.3 37.4 30.9 2-meth. phenoxy alpha-butryic Spray 26.2 43.5 31.1 2-meth .. 4-bromophenoxyacetic Spray 25.1 36.2 28.3 2,4-D (isopropyl ester) in sulphur Dust 21.3 1 28.7 21.4 2,4-D (s odium salt) Spray 16.3 1 36.4 28.8 Control 28.6 32.3 24.3 'Statistically significant , Diff e ren ce between means of 6.9 requir e d for significance at 1% level.

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GARDNER, REECE AND HORANIC: PRE-HARVEST DROP g obtained with 15 gals. of spray per tree. Temperatures during the time of appli cation ranged from 74 to 82 F. The dust treatments were applied on Octo ber 19, a still day on which the tempera ture varied from 74 to 77 F. All previous drops were removed from be neath the trees and subsequently all drops were gathered and counted, begin ning November 1 and at weekly inter vals thereafter until the crops were harvested, the Pineapple oranges on February 14 and the Valencias on May 4. The first three compounds listed in table 1 had previously been found to be very effective (in a class with 2,4-D) in delaying abscission of Coleus petioles a test used by Gardner and Cooper (2) to screen a large number of compounds for effect on abscission. It is. evident that none of the three had any influence in controlling the drop of either of these orange varieties. The data in table 1, however, serve to show the very heavy fruit drop frequently encoun tered in Florida citrus, and that 2,4-D applications effected an appreciable control of this drop in Pineapple oranges but not in Valencias. The re duction in drop of the Pineapple oranges with the 2,4-D spray amounted to 43.1 percent of the drop from the con trol trees. The dust application was less effective, due probably to the poorer coverage than can be obtained with sprays. Fruit splitting in the Valencias was quite severe during the fall and winter of 1948 in this test grove and therefore all Valencia drops were separated as to split and sound fruit and counted separately. The subtraction of splits from the total drops as presented in the Valencia section in table 1 did not alter the conclusion that 2,4-D had no effect on drop in this variety. Neither was there any influence of this compound on the amount of splitting. 1949 Experiments Because of the frequent use of wet table sulphur sprays in Florida for rust mite control, it was important to learn if 2,4-D could be added to such sprays instead of making a separate applica tion. The 1949 experiments were de signed to test this point, as well as to investigate the possibility of higher concentrations of 2,4-D. Both Pine apple and Valencia varieties were in cluded in these tests, which included 6 treatments with 10 replications. The 2,4-D (sodium salt) was used at 25 and 50 p.p.m., both with and without wet table sulphur (10 lbs. per 100 gal.) Dual control treatments were set up consisting of (a) no spray and (b) sulphur only. Table 2 discloses a very appreciable TABLE 2. THE EFFECT OF 2,4-D WITH AND WITHOUT SULPHUR ON PRE-HARVEST DROP OF PINEAPPLE AND VALENCIA ORANGES. Tr e atments-Sprays Applied December 19, 1949 Control-(no spray) Control-wettable sulphur only 2,4-D at 25 p.p.m. 2,4-D at 25 p.p.m. with sulphur 2,4-D at 50 p.p.m. 2,4-D at 50 p.p.m. with sulphur Drop in Percent of Total Crop Pineapple Valencia Picked Feb. 13 Picked May 5 16.8 14.7 18.7 15.4 6.8 1 17.9 6.1 1 17.4 4.0 1 19.8 5.3 1 14.0 •Statistically significant. DiHcrcncc betwem means of 5.88 needed for significance at the 1 'lo level.

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FLORIDA STATE HORTICULTURAL SOCIETY, 1950 and highly significant reduction of fruit drop in the case of Pineapple oranges at both concentrations of 2,4-D. The higher concentration (50 p.p.m.), while appearing to be the more effective, is not significantly so, and the use of this high concentration would not seem justified. In this experiment the use of 25 p.p.m. resulted in a saving of 1.7 boxes of fruit per tree, compared with the average drop of the controls.' It is evident from table 2 that 2,4-D can be combined with wettable sulphur without loss of effectiveness. Appar ently there is considerable leeway in the timing of the 2,4-D application (October, November, or December) and combining it with wettable sulphur will rarely present interference with the timing needed for rust mite control. The 1949 trials with 2,4-D, like those in 1948, were without effect on Valen cias. These results are in marked con tradiction to those reported from Cali fornia with this variety. Until more work is done with Florida Valencias, the reason for this disagreement in re sults can only be surmised. Trees sprayed in May or June in California are in a much more active condition than the trees in Florida that were sprayed in the fall and winter. It is possible that the difference in time of spray application is responsible and that earlier application would be effec tive in Florida. If this is the correct explanation, it is strange that the Flor ida Pineapple trees respond so marked ly to 2,4-D at any time during their dor mant period. Effect On Other Varieties Sweet seedling oranges, Temples, and Marsh grapefruit were also sprayed in 1 A concentration of 25 p.p.m. of 2,4-D was made by adding 2.1 oz. of the commercial sodium salt ( 83 percent 2,4-D equivalent) to 500 gal. of spray. Be cause it is readily soluble in water, it was added directly to the spray tank and agitated briefly before application. 1949. The treatments consisted of con trols and 2,4-D sprays at 25 and 50 p.p.m. without wettable sulphur. Each treatment was applied to single-tree plots with 10 replications. Unfortun ately, picking crews harvested the crops without notifying the experimenters and thus no record of the amount of crop on the trees at picking date was obtained on which to base percentages of drop. With only the week-by-week pick-up record of dropped fruit from the sprayed and non-sprayed trees, no definite statement can be made as to the effectiveness of the sprays on these three varieties. The partial data, how ever, suggest that 2,4-D was reasonably effective on sweet seedlings and Temple oranges but was not at all effective on Marsh grapefruit. Injury To Citrus From 2,4-D Fall and winter applications of' 2,4-D at a time when young growth is not present and not anticipated for some weeks to come, have not resulted in any observable effect on the foliage on the tree at the time. In the following spring when new foliage appears there are nearly always a few leaves to be found that show 2,4-D effects. This is true almost regardless of the weakness of the concentration used. The deformed leaves are few in number and may not appear except on occasional trees, and they are not cause for alarm. The lack of damage from low concen trations of 2,4-D should not lull the grower into the belief that high concen trations can be safely applied to or around citrus. A disastrous instance was observed in which 2,4-D at 1000 p.p.m. was applied to eradicate a dense stand of Callicarpa americana, growing as a weed in a block of Pineapple oranges on Rough lemon roots. The application was made in midsummer and care was taken to avoid spraying the trees direct ly. A heavy rain shortly thereafter

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WANDER AND REITZ: COMPOSITION OF IRRIGATION WATERS 11 washed the 2,4-D down to the Rough lemon roots and resulted in severe dam age and eventual death of the trees. The same weed in another grove nearby was treated in the same manner with the same spray and on the same day. This grove was on sour orange roots and in somewhat heavier soil. It escaped any visual damage. Presumably the differ ence in response can be attributed chiefly to the difference in rootstock,-the Rough lemon apparently being more sen sitive than sour orange. Acknowledgments We wish to express our thanks to the Chase Investment Company at Winder mere, Florida, for their generous co operation and assistance in applying the sprays for the Pineapple and Valencia tests. Our appreciation is also extended to Mr. G. F. Randall of Orlando for per mitting the use of his groves for certain of the experiments. LITERATURE CITED 1. GARDNER, F. E. Practical applications of plant growth substances in horticulture. Proc. Fla. State Hort. Soc. 54: 20-26, 1941. 2. GARDNER, F. E., and CooPER, W. C. Effective ness of growth substances in delaying abscission of Coleus petioles. Bot. Gaz. 105: 80-89, 1943. 3. GARDNER, F. E., MAHTH, PAUL C., and BATJER, L. P. Spraying plant growth substances for control of the pre-harvest drop of apples. Proc . Amer. Soc. Hort. Sci. 37: 415-428, 1939. 4. STEWART, \V. S., and KLoTz, L. J. Some effects of 2,4-dichlorophenoxyacetic acid on fruit drop and morphology of oranges. Bot. Gaz. 109: 150-162, 1947 . 5. STE,vART_, \V. S., and PARKER, E. R. Preliminary studies on the effects of 2,4-D sprays on pre harve.st drop, yield, and quality of grapefruit. Proc. ,\mer. Soc. Hort. Sci. 50: 187-194, 1947. THE CHEMICAL COMPOSITION OF IRRIGATION WATER USED IN FLORIDA CITRUS GROVES I. W. WANDER AND ' H. J. REITZ Citrus Experiment Station Lake Alfred A knowledge of the chemical com position or mineral content of irrigation water is of great importance to growers because of the known detrimental effects to plants of highly mineralized water. Although water from various sources has been used for irrigating citrus in Florida for many years little is known of the actual chemical com position of much of the water which is used. A report made 50 years ago indi cated damage to citrus when irrigated with artesian well water (9). A more recent report (14) indicated that many wells in several East Coast districts were increasing in salt content thus in creasing the possibility of damage when used on groves. Similar increases in saltiness have been experienced with municipal water supplies for several coastal cities (8) (10). In most areas where irrigation is required, the annual rainfall is gener ally low. Such conditions result in ac cumulations of salts in the soil, because there is little or no loss of the salts through leaching by rainfall. Since practically all of the citrus growing area of Florida receives annually 50 to 60 inches of rain (4) accumulations of salts are not likely to occur from year to year. Leaching of applied salts is also aided by the fact that most of the soils on which citrus is growing in Florida is of a very sandy porous na ture and easily leached. Since these soils contain practically no clay which exhibits exchange capacity, additions of sodium from salt water does not destroy their structure thus impeding leaching as often happens in many regions using irrigation. For these reasons the use of irriga tion water on citrus in Florida presents a different problem than found in many other citrus growing areas. In fact,

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12 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 water containing greater amounts of salts can be used under the climatic and soil conditions found in Florida than could be used if the climate were drier and the soils heavier. This was pointed out in work done by Young (15) using known concentrations of sodium chloride solutions on citrus seedlings . growing in pots in the greenhouse. He concluded that relatively high concen trations of sodium chloride alone were not detrimental to growth. Previous analysis of irrigation waters (14) involved only the determination of the chloride content and a calculation to the equivalent amount of sodium chloride. Some preliminary work with water samples taken in 1949 showed that the amounts of sodium found were not sufficient to account for all the chlorides present, thus indicating the presence of other minerals such as cal cium and magnesium chlorides. This is to be expected because the mineral composition of the water will be deter mined by the minerals dissolved from the rock and mineral deposits through which it passes plus that contributed from any infiltration by sea water. Sev eral reports (5) (10) have listed the chemical constituents found in waters from different Florida localities. Most of these analyses are for municipal water supplies and relatively less in formation is available giving data re lated to irrigation st1pplies. Thus, for several reasons, a more complete picture of the composition of water used for irrigation was felt de sirable in order to more correctly evalu ate such water. It is the purpose of this report to list the composition of waters from widely different localities which are used for irrigating or for mixing sprays for citrus. Collection of Samples Clean quart mason jars fitted with a jar rubber and glass top were used to transport water samples to the laboratory for analysis. An effort was made to obtain samples from wells which were in use, since it is known that a lower mineral content is often found in wells which have not been used for several weeks or months. After the well has been in use for several hours the mineral content becomes relatively stable. Methods of Analysis The methods of analysis used were of a type primarily fitted to water analysis. Several of the methods are relatively recent developmen"ts and will be men tioned briefly . pH measurements were made using a glass electrode. Specific conductance was measured in mhos x 10 5 at 25C. This measure ment is directly related to total dissolved solids in the water. Calcium was determined by titrating an aliquot of the water with versene (disodium dihydrogen ethylenediamine tetracetate dihydrate) using ammonium purpurate indicator (2) (6). Magnesium was measured by titrating a portion of the water with versene using errochrome black T indicator which gives a value for the total magnesium and calcium present. By subtracting the amount of calcium previously found the magnesium concentration can be found (2). Sodiurn was estimated through the use of a flame photometer (1) (12). Chloride concentration was found by titration with mercuric nitrate using diphenylcarbazone bromophenol blue mixed indicator (3). Sulfate content was measured by pre cipitation under controlled conditions with barium chloride and reading the re sultant turbidity with a photoelectric colorimeter ( 11). Carbonates and bicarbonates were esti mated by titration with standard sulfuric acid using phenolphthalein indicator for

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WANDER A D REITZ: COMPOSITION OF IRRIGATION WATERS 13 the carbonate endpoint and methyl purple for the bicarbonate endpoint ( 7 ) . A qualitative analysis of several of the wells containing the large st amounts of dissolved solids was made by a spectro graphic procedure. Relationship of Specific Conductance and Total Dissolved Solids Twenty-four water samp les represent ing the East Coast, West Coast and Cen tral Florida were evaporated to dryness and the resulting salts weighed. The total dissolved solids in parts per million thus determined were compared to speci fic co nductance values obtained with a conductivity meter. Fig. 1. The rela tionship was found to be directly propor tional and if the specific conductance in mho s X 10 5 at 25 C. is multiplied by 7 the concentration of so luble sa lts is ob~1300 :,, 1200 (.\J 1100 t<( 10 'P Q ,c 8 (/) 700 0 :I: 600 2 500 t400 > Z tained directly in parts per million. This relationship is the same as found in other areas of the United States where water a naly ses are made ( 1 3 ) . Since the speci fic conductance of a water sample i s very easily obtained (comparab le to the time required for a so il pH determination ) it can be seen that such a measurement is of great va lue in rapidly evaluating a water source. It is probably the best si ngle index for deciding the advisability of using water for irrigation in Florida. Average Chemical Composition of Water from Nine Florida Counties The maximum , minimum and average amounts of the var ious elements deter mined along with pH, total dissolved so lid s and calculated a mount of sodium c hloride in water from severa l localitie s is given in Table 1. The sod ium chloride 8 1 __l ~~"" I I --~ 100 ~ 0 -~ 2 ~ 0 --= o = o 3 = 000 4000 sooo 60~ 1000 i ~ao'oo 9000 _ PPM TOTAL DISSOLVED souos Fig. 1. Relationship between parts per million total dissolved solids and conductivit11 m , eas1 . wements of i1Tigation watet .

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14 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 content is given simply for a basis of comparison with previously published figures. As previously mentioned it does not represent a true picture, however, since all the chlorides found cannot be a,;sumed to be sodium chloride. From this table it can be seen that individual wells within the same locality vary considerably in mineral content. This is to be expected because all wells are not at the same depth and conse quently tap different water strata. This great variability stresses the need for careful consideration of local conditions and if a new well is to be drilled a geolo gist familiar with local conditions should be consulted. Further study of this table reveals the great variation between lo calities in water composition. For ex ample on the mainland of Brevard County there was on the average 1283 p.p.m. of chloride ion and 107 p.p.m. of sulfate ion whereas in Sarasota County there was only 202 p.p.m. of chloride ion as compared to 836 p.p.m. of sulfate. In one case the water was primarily chloride TABLE 1. MAXIMUM, MINIMUM AND AVERAGE COMPOSITION OF WATER FROM INDEX WELLS IN NINE FLORIDA COUNTIES IN 1950. No. Parts Per Million Locality Samples pH T.D . S.' Na Ca Mg Cl Brevard Co. Islands Brevard Co. Mainland Indian River Co. St . Lucie Co . Pinellas Co . l'.fanate e Co. Sarasota Co. Charlotte Co. Le e Co. Polk Co. Wells P o lk Co. Lakes l\fax. 8.40 15000 Min. 7.50 763 57 Aver. 8.20 1 3106 Max . 8.40 7217 Min. 7 . 65 1484 10 Aver . 7 . 95 2580 Max. 8.40 1442 Min. 7.30 833 38 Aver. 7.79 1099 Max. 8 . 30 3570 Min. 7.30 714 55 Aver. 7.81 1528 l\lax. 8.40 2280 Min. 6.98 J 68 21 Aver. 7..54 887 Max . 7.85 24 , 30 Min . 7 . 3.5 441 26 Aver. 7.60 1043 !'\lax. 8 . 20 2280 l\li11 . 7 . 3 . 'i 644 14 Awr. 7 .. 54 1314 Max. 8.60 .5240 Min. 7.20 1010 11 Aver . 7 . 67 248.5 Max. 7 .80 2580 Min. 7.30 1554 9 Aver. 7.59 218.5 Max. 7.65 221 Min. 7.40 168 2 Aver. 7.52 194 Max. 7.20 98 Min. 6 . 55 35 9 Aver . 6 . 93 69 1 Arithmetic mean of individual values. Total dissolved solids calculated from conductivity. 4800 514 110 62 688 170 2100 269 269 76 624 132 260 96 124 47 179 64 869 116 90 37 295 72 590 246 0 22 129 70 360 289 0 60 58 151 245 46 ; 3 24 78 60 2.5.5 1180 241 158 67 468 1.50 530 130 270 71 411 102 8.1 37.2 5.5 29.2 6.8 33 . 2 9.0 6.4 5.1 1.4 7 4 635 7745 27 . 225 108 1432 223 3872 39 605 87 1283 68 527 46 225 57 371 110 1494 23 151 .59 538 67 1626 2 18 2.5 296 116 822 28 18 6fi 162 1,52 , 'i20 .50 30 f)(j 202 19,5 2109 45 302 93 97,5 101 974 61 457 87 774 7.1 9 . 6 5.6 6.2 6.4 7.9 5 . 3 18 . 8 2.6 9.6 3 14 SO, CO, HCO 3 NaCl 1200 34 203 230 0 107 230 38 106 384 48 138 120 0 -3 0 .590 137 387 l.'i26 29!; 8;36 771 48 302 379 240 305 2.4 2.4 2 . 4 31.2 16.8 23 14 135 0 7 8 105 16 156 0 7 5 94 16 159 6 99 12 133 2,5 299 6 90 13 137 19 228 0 10 fl 14 , '3 19 164 0 35 6 129 16 170 0 84 .5 121 16 14,5 0 48 6 100 16 180 0 96 11 145 0 144 0 108 0 126 0 22.6 0 3.1 0 13 12768 371 2349 6383 997 2116 870 371 607 2463 249 887 2681 30 488 13.56 30 272 857 50 ,13 3 3477 499 1607 1605 754 1276 16 10 . 13 31 16 23

PAGE 37

WANDER AND REITZ: COMPOSITION OF IRRIGATION WATERS 15 " U O lO~0.-t.-t lO 00 .-t t:... c,-; oo o..; "'1' 00"'1'000 .., CNCN"
PAGE 38

16 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Trend in Salt Concentration of East Coast Wells Table 3 records the changes found in wells from several East Coast areas from the period 1942 to 1950. More wells were sampled from 1944 to 1950 and that data is included separately. In eight out of eleven areas sampled from 1942 to 1950 there was an increase in salt concentration. With more samples taken from 1944 to 1950 six areas out of 12 showed an increase while the other six areas decreased. In all cases the increase or decrease was slight and the trend either way was related to a defi nite region. For these wells it would appear that changes take place rather slowly. Other Elements Found in Water One of the objectives of this investi gation was to determine what other ele ments might be present in addition to the usual constituents. Examination by spectrographic means of residues from 16 wells showing the highest concentra tion of soluble salts revealed considerable amounts of strontium present in all sam ples. A quantitative analysis of one sample showed approximately 30 p.p.m. strontium present. The effects of stron tium on citrus are not known but it is known to be toxic to some plants. Experi ments have been started to estimate its effect on citrus. No barium, potassium, or lithium was present in the samples examined although these elements are often present in natural waters. Summary 1. The total soluble salts present in an irrigation water is probably the best single index to use in evaluating the water. 2. The climatic conditions and soil types in Florida permit the use of water containing greater amounts of soluble salts than is ordinarily considered safe. 3. It is essential that, when irrigating with a high mineral content water, the soil moisture is maintained as high as practical. 4. Individual wells in the same area vary considerably in soluble salt concen tration and different areas vary as to the type of soluble salts present. 5. Strontium was found in the water TABLE 3 CHANGES IN SALT CONCENTRATION (CALCULATED AS P.P.M. NaCl FROM Cl CONTENT} IN INDEX WELLS IN THE INDIAN RIVER . AREA ,57 Wells Sampled from 1942 88 Wells Sampled from to 1950 1944 to 1950 Locality No. No. Wells 1942 1944 1947 1950 Wells 1944 1947 1950 Brevard Mainland 1 1235 1320 1360 1587 3 1263 1250 1370 Courtenay 3 5712 6227 6080 Merritt-Indianola 12 2123 2105 2120 2162 19 2134 2155 2170 Georgiania-Footman 6 1668 1765 1657 1771 6 1765 1657 1771 Lotus 6 1331 1472 1540 1533 10 1481 1527 1494 Tropic 2 875 1138 1080 1058 3 1068 1047 1029 Oslo 4 465 486 488 502 4 486 488 502 N. W. Vero Beach 7 539 614 641 592 11 611 625 609 S. W. Vero Beach 10 598 646 655 592 13 630 650 604 Ft. Pierce farms 4 683 750 720 673 8 703 669 658 Ft .. Pierce Vicinity 3 576 627 613 629 . 6 633 632 620 White City 2 1003 1015 1010 967 2 1015 1010 967 '

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GUNTEH: GHOUND WATEH HESOURCES 17 from wells on both the East and West Coasts of Florida and may or may not present a hazard to citrus. 6. The increase in saltiness of wells on the East Coast is slow and confined to certain districts. LITERATURE CITED 1. BERRY, J. w., D . G. CHAPPELL , and R. n. BARNES. Improved m e thod of flam e photom e try. Ind. Eng. Chem., Anal. Ed . , 18:19. 1946: 2 . BETZ, J. D . , and C. A. NOLL . Total hardness in water by direct colorimetric titration. /our. Amer. Water ,vorks A.vsoc. 42:49-56. 1950. 3. CLARKE, F. E. Determination of chlorid e in water. A!lal. Chem . 22:553. 1950. 4. Climate and Man. Y earl,ook of Agricultur e . pp. 809-818. 1941. 5. COLLINS, W. D., and C. S. HmVARD. Chemical charact e r of waters of Florida . Dept. of th e Interior . Water Supply Paper. 596-G. 1927 . 6. DIEHL, H., C. A. GOETZ, and C. HACH, The versenat e titration for total hardness. Jour. Amer. Water '\Vorks A.,soc., 42:40-48. 1950 . 7. Official and T e ntativ tl Mt thods of Analysis . A . O.A.C. , p . 640, 6th Ed . 1945. 8. PARKER, G. G. Salt water encroachment in Southern Florida. ]ottr. Amer . ,vat e r ,vorks Assoc. 37 : 526-542. 1945. 9 . ROBINSON, M . R. Report on fertilizers and irrigation. Proc. Fla. Stat e Ilort. So c . I!l: 140145. 1900. 10. STRINGFIELD, V. T. Ground water resources of Sarasota County, Florida . Twenty-third, twl'nty fourth annual report. Fla. State Gcolo[!.i c al Survey. P. 176. 1930-32. 11. TREON, J. F. and W . E. CRUTCII F IELD, )R. Rapid turbidirnetric method for det e rmination of sulfates. Ind . Eng. Ch e m ., Anal. Ed. 14:1J9 . 1942. l" ,VEST, P. ,v., P. FOLSE, and D. !'.foNTGO>tERY. Application of flame sp e ctrophotom e try to water analysis. Anal. Chem., 22 : 667. 1950. 13 . \V1Lcox, L . V. Explanation and intl'rpretation of analysis of irrigation wat e r. U.S . D.A. Circular No. 784. May 1948. 14. YOUNG, T, \V , , and V. C. JAMISON. Saltiness in irrigation w e lls . Proc . Fla . Stat e Hort. Soc. 1944. 15. YouNG, T. W. Florida Agricultural Experiment Station. Ann11al Report. P. 288. 1949. GROUND WATER RESOURCES OF FLORIDA HERMAN GUNTER Fforida Geological Survey Tallahassee Introduction All life depends upon water for its very existence. As an essential to human life , water is second only to the air we breathe. It is therefore the more de plorable that this commodity on which our existence depends continues to be wastefully and unwisely used with either complacent disregard for, or no thought of, the consequences of such practices. Periodic deficiencies brought about by droughts, by local overdevelopment or by occasional breakdown of the water supply sys _ tem may tend to impress upon us the importance of an adequate water supply, but as soon as our temporary inconven iences are removed we again fail to ex ercise discretion in protecting our water resources. Water is the most valuable and priceless resource that any community, county or state possesses. The short age recently experienced by New York City has quite forcefully focused atten tion upon the necessity of an ample wate1 supply, and this has had a stimulating influence on Nation-wide thinking about water resources. In regions like Florida blessed with generous rainfall and with formations adapted to storing it, there is at least more reason for the prevailing general idea-and often firm conviction-that water supplies are inexhaustible and may be used or cast away without concern as to the effect on future supplies. Yet even in these regions where provident Nature has been extremely generous, there is evidence of an increasing con cern about the adequacy and permanence of water supplies. This awakening has come about gradually the hard way-by actual experience. With rapid increase both in ' population and in industry great er and greater demands for water are

PAGE 40

18 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 made, and in supplying these increasing demands arresting problems have arisen. Everyone should realize that water is an exhaustible resource and should in all uses treat it accordingly. In providing water there should be rather clear ideas as tothe source to be tapped, the develop ment of the well field, the movement of water underground into the area, and the general character of water that may be obtained. With the accumulation of such information and the assimilation of such data it is possible to more intelligently and satisfactorily locate wells, let con tracts for drilling, develop the supply, and guard against contamination as well as possible infiltration of salt water. Source of Our Water Supply A very general and popular explana tion of the source of artesian water in Florida is that it originates in the moun tainous regions of states to the north, and in spite of all that has been said through the years to the contrary, this idea still persists. Except for those por tions of the State bordering Georgia and Alabama, all the ground water in Florida comes from rainfall within the State, and even in northern and western Flor,... .. -::,,... ---~ ,'1-o E.:\.~I, '\.,. !o.,...,< i: ,. _ ..... /'r>O \\ ",: ., 0 ' , L. , 0 :;:;., )\i\ EXPLANATION-Contour lines represent approximately the height, in feet, to which water will rise with reference to mean sea level in tightly cased wells that penetrate the principal artesian aquifer. Contour intervals 20 feet . . Stippling indicates area of flowing wells. Plate I. Map of Florida Showing Piezometric Sitrface of Main Artesian Aquifer and Area of Flowing Wells.

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GUNTER: GROUND WATEH RESOURCES 19 ida the ground water originates in local rainfall, but here it is supplemented by contributions from southern Georgia and Alabama through contiguous surface and subsurface formations. The formations in the northern mountainous regions are vastly different in age and character from those at or near the surface in Florida and, if the former are present in our State, they lie at great depth with no influence on or connection with the artesian reservoir. Furthermore, the water from these deeply buried forma tions is known to be highly charged with mineral solids and too salty for public and domestic use. Geology of Florida History records that Ponce de Leon was in search of the "Fountain of Youth." Without doubt some early ex plorers had related fantastic and _fasci nating stories about the large springs of this newly discovered world which so intrigued Ponce de Leon that he felt compelled to search for this land of "Eternal Youth." So it may be inferred that hydrology played a leading role in focusing world attention to this portion of the United States. Be that as it may, Florida does have an interesting geological history. All of the formations present at the surface, and to a considerable depth, are of sedi mentary origin and geologically speaking are recent or young. Underlying these formations, however, we know there are still older sediments that rest on older rocks, some of which are metamorphic and some igneous in character. This rock sequence indicates that Florida has been here since quite ancient time. To better understand the occurrence, movement and development of ground water one must turn to geology as the source of help. _ There is a very close relationship between the occurrence of ground water, the configuration of the ground surface, and the character and structure of rock formations, all of which influence the accumulation, rate of move ment and direction of flow of water under ground. Let us consider briefly the geology of Florida, and limit the discus sion to those formations most important to water supply. All of the surface or exposed forma tions in Florida are included within the latest major division of geologic time, termed the Cenozoic Era, meaning more modern time. In Florida there is com plete representation of each series in this era from the oldest to the youngest. The most important of these in relation to water supply are: 1) the Eocene, includ ing the Ocala and older limestones, 2) the Oligocene, mainly the Suwannee and Marianna limestones, and 3) the Miocene, of special interest because of develop ment in peninsular Florida and the local names of Tampa limestone and Haw thorn formation. Also the more recent Pliocene and Pleistocene formations, since these are of importance, especially in western Florida and along the lower East Coast. The principal artesian water forma tion, or aquifer, is the Ocala and the older Eocene limestones. It is from these limestones that the great volumes of water are derived in peninsular Florida. In earlier literature the Ocala limestone was mistaken for the Vicksburg lime stone, named from its typical exposure at Vicksburg, Mississippi. This name is still applied incorrectly by some citizens of the State, although the term Ocala limestone has been used many, many years, and has here replaced . the term "Vicksburg" in scientific usage. Well drillers are familiar with the Ocala lime stone and are quite proficient in deter mining when it has been penetrated, since the limestone is usually fairly soft, granular and white to . cream-colored, often full of fossils. These Eocene lime stones are known to underlie all of Flor ida with the possible exception of the

PAGE 42

:W FLOHIDA STATE HOHTICULTUHAL SOCIETY, l!:J5U extreme western portion of the State, and here the lack of subsurface data may account for its apparent absence or its having not been recognized . Lying immediately above the Ocala limestone is a group of Oligocene lime stones to which appropriate names have been given, and all have physical charac teristics quite similar to the Ocala lime stone, except the Marianna, which is finer grained but resembles in many re spects the Ocala limestone in that it is soft, cream-colored and generously fos siliferous. The Byram marl is of local occurrence and does not play a prominent part in relation to water supplies, but the Suwannee and Flint River limestones are good aquifers. These limestones are rather hard, white to cream-yellow, and quite pure, the calcium carbonate con tent being comparable to that of the Ocala limestone. It is the Suwannee limestone that yields the generous supply of water developed by the City of St. Petersburg and is currently being con sidered as a source for the entire Pinellas Peninsula. Of the Miocene formations, the Tampa limestone and Hawthorn formation are of most importance, because of their wide distribution and general characteristics. The Tampa limestone is yellowish in color, fairly hard, and less pure than the Suwannee and Ocala limestones. It often contains as much as 25 percent silica, some alumina and ordinarily very little magnesium. This limestone upon weath~ ering, therefore, leaves quite a residue of insoluble materials. It is, however, an important acquifer. The Hawthorn formation varies from a rather pure to a phosphatic limestone with large percentages of sand, marl and clay. In some parts of the State it is largely made up of thick beds of clay and sandy clay. Under such conditions it acts as an impervious bed, confining the water in the underlying limestones under artesian pressure. It contains 0 0 (N "O Q,) s:: i::: oil Q,) c.> ...., 0 i::: .... Q,)P-< 0 0 C'.) .-< 0 t:,o Q,) ;.. i::: oil 0 .....:l..., rf,J >. Q,) Q,) E :::4;::: i::: O ~ oil E I-< 0 .... Q,) c.> 0 .... rf,J a3 p:: rf,J p.. E 0 ..c:: E-<

PAGE 43

Alachua formation 100 Bone Valley formation 50 <>-• Buckingham marl 45 rn ;::l Caloosahatchee formation 50 0 Q) s:: Pliocene ... 0 Charlton formation 60 0. E Citronelle formation 250 Q) ..., s:: 0 u Tamiami formation 100 Duplin marl 50 s:: >, Shoal River formation 170 0. ;::l 0 ..., Q) 0 rn S:: ::?:: ... g -0 Chipola formation 56 C, oil us:: .... >-:, Miocene '+-< ;::l s:: >,~ E 0..., oil rn S:: QJ ;:I g -0 Hawthorn formation 500 :;: 0: us:: >-:, 0: Tampa limestone 120 Sand, clay, and phosphate. Sand, clay, and phosphate. Calcareous clay. Sand, shell, and marl. Yields water to shallow wells. Some of the water is highly mineralized. Calcareous clay and impure limestone. Sand, gravel, and clay. Yields water to shallow wells. Sandy limestone to nearly pure quartz sand. Important source of water to shallow wells. Sandy shell marl containing clay. Yields water to shallow wells and in part artesian. Fine micaceous sand and sandy clay. Sandy limestone and sand with shell. Yields water to shallow wells, in part artesian. Interbedded sand, clay, marl, and limestone, with lenses of fuller's earth. Important source of water, in part artesian. Locally the water is highly mineralized. Limestone and sandy limestone, in places dolomitic. Important source of water, much of which is under artesian pressure. In local areas near coast water is highly mineralized. () C z ,-3 M ::,:: () :,:: 0 C z ti g; U'} 0 c:::: ::,:: Ci M U'} l-=> ....

PAGE 44

I Hard, resonant limestone to soft, granular 0 r/.l Suwannee limestone 100 limestone, containing some silica. Importi:i. ::s E o ant source of artesian water. Cl) Cl) .;.> i:: i:: d Flint River formation Sandy and pebbly limestone and calcareous 0 i... u (Northwest Florida) 100 dirty sand. Locally silicified. Oligocene Byram limestone 40 Limestone, sandy limestone and some clayey beds. Limited areal extent. Chalky limestone. Locally an important Marianna limestone 30 source of water in Jackson, Holmes and (Nor.thwest Florida) Washington counties. Predominantly porous limestone. Important source of water, most of which is under Ocala limestone 360 artesian pressure. In local areas the water is highly mineralized. Chalky limestone containing some gypsum Avon Park limestone 650 and chert. * Crystalline limestone, argillaceous limeEocene Tallahassee limestone 650 stone. ,cChalky limestone locally containing gypL a ke City limestone 500 sum and chert. ~I Oldsmar limestone 1,200 Predominantly limestone but contains some 0 r/.l i:i. ::s . . gypsum and chert. E o Cl) Cl) ..., i:: Salt Mountain limestone 200 Soft, chalky limestone. S:: d 0 i... (Northwest Florida) ::i I Cedar Keys limestone 570 0 r/.l Hard limestone. i:i. ::s 8 0 Paleocene Cl) Cl) Brittle, gray to black clay. i:: Porters Creek formation Several i:: d 0 i... (Northwest Florida ) hundred ::i *Water in these beds combme with the water m the Ocala hmestone. After Cooke. Prepared by: Florida Geological Survey, P. 0. Drawer 631, Tallahassee, Florida. .... 0 ::c ..., 0 c::: t: ..., c::: :;:: > t:.....
PAGE 45

GUNTER: GROUND WATEH HESOUHCES 23 varying quantities of water and in some sections is important. It is the phos phatic limestone portion of the Haw thorn formation that yields water in some areas so high in fluoride content that it is detrimental to tooth enamel in children. The several formations grouped col lectively under Pleistocene and Pliocene are all water-bearing, and water from these surface or near-surface forma tions is being developed extensively at present, especially in the southern por tion of the Florida Peninsula where the deeper lying artesian water is generally quite salty. These formations consist of limestone, shell marl, coquina and sand. Ordinarily the quality of the water in these upper formations is bet ter than that in the deeper artesian aquifers, but the quantity is far less. One exception, however, is the Tamiami formation of southern Florida from which Miami and other cities of Dade County get copious water supplies. Ac cording to the United States Geological Survey, the Tamiami formation is "one of the most productive aquifers in the world.'' In western Florida one of the best water supplies in the State is obtained from sand. At Pensacola, for instance, wells are about 250 feet deep and the water is almost as soft as rain water, with a mineral solids content of only 41 parts per million. In some parts of Florida the water from these shallow formations is high in iron, causing ob jectional staining. Piezometric Surface in Florida Since its establishment in 1907, the Florida Geological Survey has cooper ated with the United States Geological Survey in geologic . and ground-water studies. During the past twenty years these studies have centered almost entirely on ground water. This re search has given us much practical information about the geology, the char acter and capacities of the several formations, also the direction of flow and rate of movement of ground water. These studies have enabled us to con struct a map showing the height above sea level to which water will rise in wells that penetrate the artesian forma tions. To construct such a map it is necessary to measure the depth to water -or to obtain pressure head in areas of artesian flow-in wells throughout the State, and to know the elevation of each observation well. With this informa tion it is possible to plot the wells on a map and to show by contour lines the surface to which water will rise from a given formation, or group of formations acting as a hydrologic unit. This is called the piezonietric surf ace. See Plate I. This map is most practical. With it the well driller can, with a large degree of accuracy, estimate the level at which water will stand above sea at any local ity along a given contour, and from this determine the best type of pump in stallation for the most satisfactory job. The map also shows the areas of "piez ometric highs," as for instance, the one in Polk County which is the principal source for artesian water in central and southern peninsular Florida. These piezometric high areas are also termed recharge areas, while those where such surface is low are called discharge areas. Furthermore, the map readily indicates the general direction of artesian water movement, which is more or less perpendicular to the contours, moving from high to low contours. And finally the map outlines the areas where the piezometric surface rises above the land surface or the area of artesian flow. Unfortunately, within this area the artesian water is very highly charged with mineral solids, in some in stances too high for use.

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24 FLORIDA STATE HOHTICULTUHAL SOCIETY, 1950 Factors Affecting Florida's Water Supplies The source of the abundant water supply in Florida is rain. Variations in rainfall bring about periodic droughts and floods. During droughts we become alarmed about the adequacy of the water supplies, during floods we too eagerly dispose of excesses as rapidly as possible. This excessive, rapid dis posal by drainage, without due consid eration of needed storage basins or reservoirs to hold the excess for release in time of low supply, has undoubtedly contributed to some of the problems now confronting the State. Glancing over the rainfall record of the United States Weather Bureau, 1937-50, or the last 13 years, it is seen that the average annual rainfall for Florida was 55.37 inches, the lowest was 43.17 inches in 1938, and the highest was 72.37 inches in 1947. In 1949 there were only 50.13 inches and in the first half of 1950 (January-June), only 15.41 inches were recorded. Evidently, the deficiency beginning in 1949 is continu ing in 1950 with even greater severity. Although Florida does have a high aver age rainfall, the State does suffer droughts sufficiently severe to cause ex tensive crop damage, largely because of the highly seasonal character of rain fall. Low relief and very porous soil conditionR are conducive to high absorp. tion and low run-off. Evaporation is exceRRive in Florida and this together with tranRpiration accounts for an enormous volume of water loss. When Rurface water levels are high there arises a clamor for drainage and water so disposed of is lost and not available as a backlog in the dry period which is gure to follow. During the boom of the 1920's Florida literally went through a drainage spree. There just was not enough naturally dry land for all the projected subdivisions, so drainage was resorted to with abandon, the ultimate effect on the welfare of the State was never considered. To over come the harmful effects of over-drain age, consideration should be given to the construction of baffles, or retaining structures, to control the run-off and permit the impounding of as much of the water as safely possible. This could later be released and used. The 1950 United States Census records an increase of 44 percent in Flor ida's population during the decade 194050, while the national gain was 11 per cent. Florida indeed is growing rapidly in population, in winter tourist popula tion and in new and expanding industries. With this development has come such in creased demands upon our water sup plies as to cause grave concern in some areas. As example, salt water encroach ment in the Pinellas Peninsula has been caused by overdevelopment for munici pal use and irrigation purposes; as a consequence that region now draws large quantities of water from the Odessa-Cosme area in Hillsborough and Pasco counties, and plans are now under consideration for further expan sion. Salt water encroachment prob lems have also confronted Fort Myers, Tampa, Panama City, and Pensacola on the west coast, and Fort Pierce, Daytona Beach, and a strip along the east coast from St. Augustine southward. As a result, attention is being given to de velopment of water supplies from the more shallow formations, but the search for such shallow supplies has not al ways been successful. However, the salt content of the artesian supply has not entirely prevented its use for irriga tion, for many artesian wells are used for this purpose even though the water may be too saline for domestic, munici pal or induRtrial purpoReR. Large industries have in recent years moved into Florida, especially the pulp mills, and these mills use tremendous volumes of water. Problems have de

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GUNTER: GROUND WATER RESOURCES 25 veloped in those areas, but so far have been met quite satisfactorily. Mineral industries also use quantities of water in processing their products. Air con ditioning is another factor causing large drafts. Last but not least, more and more water is used for irrigation. In February, 1950, the United States Geological Survey tabulated an estimate of the consumption of ground water in Florida as follows: Gals. per day Public supplies serving 100 or more people . . .. . . 160,000,000 Industrial supplies . . ... . .... 200,000,000 Agricultural supplies .... 100,000,000 . . Domestic supplies .. .. .. .... . . 40,000,000 Total ... . .... .. ....... .. . . ....... 500,000,000 This figure of 500,000,000 gallons of water per day is impressive and should cause everyone to think clearly and plan wisely when expansion is contemplated. This is particularly true in those areas where over-draft can cause the infiltra tion of salt water. Pollution in some regions, too, has caused grave concern. Such pollution is the direct consequence of natural drainage, drainage wells, the disposal of storm waters, sewage and industrial waste directly into forma tions from which potable ground waters are obtained. However serious ground water prob lems may be in some areas, there is still room for optimism on the whole. In this the following, quoted from Information Circular No. 3, Florida Geological Sur vey, "Ground Water in Florida" by H. H. Cooper, Jr., and V. T. Stringfield of the United States Geological Survey, is most pertinent: "The consumption of 500 million gallons of water a day is, of course . a heavy draft on the ground-water resources, but this draft should not be a cause for concern in regard to . the State as a whole when it is realized that the ground-water reser voirs are naturally discharging many hundreds of millions of gal lons of water a day, much of which can be salvaged and used whenever it is needed. The tremendous dis charges of Florida's large limestone springs, which rank among the largest in the world, forcibly dem onstrate the large capacity of the ground-water reservoirs. The aver age flow of Silver Springs alone is equal to the estimated total con sumption of ground water in the State." And too, large quantities of water yet untapped through central, northern and western Florida are available for the industrial future. The problems, how ever, that have developed in certain more or less limited, or local portions of Florida must certainly be taken as warnings that there is a limit to the yield of potable water, and learn from such warnings to develop and cornrnrve supplies. To do this there must be con tinuous study of the occurrence of water, the character of water-bearing formations, the depth from which sup plies can be most successfully obtained, the possible capacities of such forma tions, and other related factors. Studies of this character are in progress by the Florida Geological Survey in coopera tion with the United States Geological Survey. General State-wide studies and more detailed studies in particular areas or counties are in progress. In summary it can be said that Flor ida is fortunate in its water resources. Its rainfall is one of the highest, and its formations have maximum absorption capacity. With all the assistance Nature has so generously bestowed upon Flor ida with respect to our natural re sources including water supplies, we must learn to utilize them wisely and provide specific controls through which conservation would become a reality.

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26 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 PORTABLE IRRIGATION ON THE RIDGE MORTON HOWELL Waverly Does Irrigation Pay? This question has been asked many times by Growers located in the Ridge Citrus Producing area of Florida. If it does not pay, there has been millions of dollars very foolishly spent in the Ridge area, espe cially in the past two years. There are two methods of irrigation used in this area I am discussing. First, is with permanent installation of pumps with power units, using underground mains or conductor lines and either overhead sprinklers or portable sprinkler or flooding lines. This type requires greater initial investment with Jess operational expenditures. The second type is with portable pumps and power units and portable conductor and dis tribution pipe. With a source of water available, this type of unit can be moved from property to property, there by on an acreage basis reducing the initial investment but, increasing the operational expense. This method is used by many in the Ridge Section which has many lakes. Do you know that many Growers who were dependent on Portable Irrigation during the past spring and summer, have more money invested in the pres ent crop for irrigation than all the other production costs combined? Yes, when a property is far removed from a source of water, portable irrigation cer tainly does deplete the bank roll fast. This is true even if you own the equip ment and not just when you hire it done. In addition, it is a job which has no end until it rains. When will it rain is the sixty-four dollar question. In my opinion there are two types of irrigation. One is "Preventive" which implies not allowing the tree to develop a tight wilted leaf condition or soft fruit and the other is "Curative." This type is used in salvaging a crop or pre venting mortality of the trees. It is bad, but true that many Growers never plan on irrigation until it gets dry. Then those without irrigation get panicky and wm pay virtually any price to obtain water. Unfortunately, in many cases this type of irrigation pre sents the greatest gamble. , My initiation to portable irrigation was with a worn out Buick motor and a low head centrifugal pump. The suc tion was a 22-foot length of 6-inch well casing. There were 400 feet of 6-inch 28 gauge galvanized slip joint pipe for conductor line and 2,000 feet of 4-inch, 28 gauge slip joint pipe for conductor and distribution line. The distribution was by the flood system. I had many experiences in attempting to keep water on the tops of some of those hills or preventing washing on the hillsides. Of course, keeping pipe together going up some of the steep grades sometimes produced a problem. The principle re quirement then to operate that type of unit was the "Patience of Job." If we had the maximum of luck, we put water on part of ten acres in four twelve to fourteen hour days. As usual, during most dry periods we were working around the clock. During the late thirties after two successive dry Springs with very little irrigation and much hauling of water in barrels to groves, some decent port able irrigation equipment began creep ing into the picture. The pumps and power units were some better but the big improvement was in portable pipe. This was known as "Lock Joint Type." It was fourteen gauge zinc coated steel with enlarged or bell type female end. Inside the female end was a rubber gasket. This gasket grew tighter as

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HOWELL : PORTABLE IRRIGATION 27 water flowed from the pump. Protrud ing from the female end were two or four receptacles so arranged that when the lugs, located on the male end, fitted into these recesses and the pipe was slightly turned, it locked. In addition to being virtually leak proof, under pressure, and slightly flexible, in the event of a power unit stopping and the foot valve on the pump suction not seat ing there would not be a vacuum cre ated and causing the pipe to flatten. This was the case with slip joint pipe. The main trouble with that zinc coated steel pipe which was in sixteen foot lengths, was its weight. One man could carry it but with great difficulty. During the war years with a scarcity of labor, this presented an acute problem. The labor problem and the increased use of aluminum after World War II was the next important step in Portable Irrigation. The production of portable aluminum pipe began to appear in this territory. This was a definite improve ment. Not only a labor saver, which was greatly needed, but due to less pipe friction more water was pumped with less power through the same size pipe. With this type pipe, using 4-irich sprinklers one Grower's daughter in our organization handle s the moving of the sprinkler lines by herself. Along with aluminum pipe there de veloped more careful selection, by the buyer and seller, of the pump and power unit required for that particular job. In the past a Grower bought a pump and obtained a power unit of some description and hooked them up. The power unit might gain maximum effici ency at 2;400 RPM and the pump at 1,600 RPM but it didn't make a great deal of difference. The main object was to have at least some water flowing at the end of the pipe. At the present, one sees high head pumps, which pump a great deal of water with high pressure against much pipe friction and terrain elevation . Power units pull these pumps direct connected or belt driven. Most of them have a clutch which allows easier start ing of the power unit and priming of the centrifugal pumps. There are some Growers with prop erties not located near lakes which do the following: Drill a well and mount a turbine pump on the well with a gear head and power take off shaft extended . They put the same size pump on the various wells. Then they use one power unit and their portable pipe on all three or four properties. In selecting equipment for use in portable irrigation much thought shou ld be given to the subject. Such as height of property above level of water, size acreage, and distance from source of water. I am assuming. that you would want the most economical unit to oper ate. Beginning with a smaller unit to be used on plots located on a lake con sisting of ten acres or less. In this situation, a small power unit with small high head pump that will supply a minimum of 300 GPM with a maximum head involved, is sufficient. I would sug gest 6-inch aluminum conductor lines and 4-inch aluminum sprinkler lines. This unit, after assembling, can easily be operated by one man . This type of grove would usually have a rather steep slope and therefore, you would not want very much water flowing. With less water, the soil will absorb it without washing. Your sprinkler lines would be approximately 330 feet in length. One 330 foot line would be operating while the other was being moved. The next size unit would be a -0.igh head pump that would deliver 700-750 GPM with comparable power unit that would deliver the maximum of water required with a maximum of head to operate against. The optimum conduc tor line would be 8-inch aluminum• or with less head, 6-inch would suffice. The

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28 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 sprinkler lines would be 5-inch alumi num of 660 feet in len.gth per operating line. Where there is a maximum head to be operated against or where it is advantageous to use 990-foot sprinkler lines, I would suggest 1000 or 1100 GPM pu mp with power unit. The Big Bertha of Poitable Irrigation is the 1;500 to 1,600 GPM high head pump and power unit to match. This would use 8 -' ihch ' aluminum conductor pipe with 6~inch sprinkler lines either two 660foot operating lines or one 1,320-foot operating line. This unit is used to a good advantage where a number of 10 Or 20-acre tracts can be irrigated from one source of water. In addition it can furnish water to ' properties up to one and orie-half miles distance from a source of water and against extreme heads. ActualJ.y you are operating two conventional 660-foot lines with just one pump and power unit. The time factor is increased by inserting crosses with valves into the conductor lines. With the use of one additional sprinkler line to change frorti one property to an other the pump never ceases operation. For example, when crosses with valves are "inserted in the conductor line while it is being assembled eighteen or twenty different blocks spread over a long dis tance, can be irrigated without ever stopping the pump. Of course, it isn't economical to use on small individual acreages due to cost of moving and setting up. There are two factors of great im portance in Portable Irrigation. They are the method employed in moving and time factor between moves. They work very closely together. It is always like working a jigsaw puzzle and shortage of pipe is usually the "fly in the oint ment." Avoid successive moves where all the pipe you have is required. It is indeed difficult to always have enough pipe fo rany type of portable irrigation. Due to pipe scarcity during extended periods of drouth a bit of trading by various organizations has proven bene ficial to all involved. In other words when one organization is set up near a property of another, the organization, so set up does the irrigation for another or at least rents the pipe for that prop erty to be irrigated prior to its being moved. In the method of moving, is the all important question of what type of equipment to use in hauling the pipe. This depends on distance between moves and many times what is available to use. Almost every conceivable type of equipment is used on the Ridge. Everything from mules and sleds to semi-trailers. One organization comes up with a useful piece of moving equip ment and it is quickly copied by others. The time factor mentioned above is all important. This means primarily do not over extend yourself. During ex tended periods of drouth properties have to be irrigated even six or seven consecutive times. Therefore, to pro tect your interest or the Growers' inter est, you must be able to repeat the operation prior to the property being depleted of moisture. If you do not, the previous irrigation or irrigations have gone for naught and much is lost. Make a survey of your needs, have a reputable organization advise you as to your requirements, usually add 25 % average on these requirements and you will be in position to have an economi cal operation. There are indications that the Port able Irrigation in the Ridge area is be ing improved every year. This improve ment is being made by semi-permanent installations. This is where growers are putting in an underground per manent conductor line by a cooperative plan. Portable pumps arid sprinkler pipe . is used. This is an excellent opera

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SMITH AND REUTHER: RESPONSE TO BORON tional saving and reduces the time fac tor, as it is moving of conductor line which is the bottleneck. I think we are yet in the dark ages on Portable Irrigation. Much has been done in its development during the past two or three years. Yet more has to be done in lowering the cost per acre inch of water applied to the citrus groves. More Growers are thinking in terms of Water Conservation which is vitally necessary. More efficient facilities will have to be developed in reducing appli cation costs. More research work is necessary in order that water is not wasted. This operation of Portable Irrigation will definitely develop fast if the next ten years are as generally dry as in the past ten. In closing, I urge you to start thinking and doing some thing about this all important problem of Portable Irrigation. THE RESPONSE OF YOUNG VALENCIA ORANGE TREES TO DIFFERENTIAL BORON SUPPLY IN SAND CULTURE PA UL F. SMITH AND WALTER REUTHER U.S. Subtropical F1'uit Field Station l Orlando Previous reports on the boron nutri t n of citrus have been concerned c iefly with deficiency and toxicity re s onses. The objective of the present s udy was to maintain trees at differ e t levels of boron between these two e tremes and to observe any differences t at occurred in regard to general g owth pattern, mineral composition of t e leaves, and fruiting behavior. Twelve young Valencia orange trees v,hich were budded on Routh lemon s ock, were planted into 50-gallon con t iners filled with white quartz sand . Beginning May 28, 1947, complete n 1trient solution was applied twice , eekly at the rate of 2 to 3 liters per a plication. The rate of boron used in t e nutrient feeding was the only dif f rential variable for the succeeding t ree years. The lowest boron level 1 w s that which was supplied as im . p rities in the C.P. salts and the lake w ter used as a water source. A medium b ron level of 0.5 p.p.m. and a high of 2. p.p.m. were maintained as the other t o treatments. Four trees received each treatment. Water was applied be tween nutrient feedings in amounts that induced leaching Further details of the method of culture are presented in a previous article (6). Leaf samples were collected each year and analyzed for various major and minor elements. Trunk diameter measurements were made semi-annual ly. Fruit was allowed to develop dur ing the third year and was analyzed for total 80luble solids, micorbic acid, and citl'ic acid. Results and Discussion In general, excellent growth wa:;; made by all tree:;;. The :;;ize attained was equal to or greater than identical trees growing in soil adjacent to the plots. All growth was nearly normal in appearance except that the low-boron trees showed mild deficiency symptoms in the foliage (4) during the fall months of the second year, and the high-boron trees showed mild toxicity symptoms of occasional tip burn and yellow spots (1) throughout the test period. These symptoms were more pronounced during 1948, when the mean total boron content in dry leaf samples was 386 p.p.m., than in 1949 and 1950 when it was about 265.

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30 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 The high boron trees showed some ten dency toward forming a less compact top than the others. They had fewer, but larger, branches and a more open character. The mean tree size was nearly identical in all three treatments. This is indicated by the cross-sectional trunk area measurements in table 1. The leaf samples collected on the first three and last sampling dates shown in table 1 were mature spring flush leaves. A broad range in the B concentration within the leaf was in duced and maintained. This range was over 24-fold in the summer of 1948 and over 10-fold in the summers of 1949 and 1950. The differences in the other elements in these mature samples are relatively small. Phosphorus tends to be present in slightly greater concen trations when B is low. Such a rela tionship has previously been found with sunflowers (2). Three samplings were made from young leaves, which were developing in the fall at the time that a crop of fruit was maturing. Under these conditions the difference in the P concentration was greater than with mature leaves, although the difference appeared to diminish as the leaf approached matur ity. The concentrations of the three base elements, K, Ca, and Mg were also influenced in these younger leaves. When B was supplied in a very limited amount Mg had a tendency to enter the leaf in greater amounts, and reciprocal ly, K in lesser amounts. Calcium ap pears to have been depressed at the highest boron level. Here again it ap pears that these differences are perhaps temporary and tend to diminish as the leaf grows older. Nitrogen, manganese, copper, iron, and zinc do not appear to have been in fluenced in any way by the variation in boron supply. Sodium was determined on the same collections for which iron values are shown and showed no differences which were attributable to the rate of boron supply. From 10 to 15 pounds of oranges were produced by each tree during 1949. These were picked and analyzed on February 6, 1950. No systematic dif ferences were found in the yield, fruit size, rind thickness, juice content, or percentage of total soluble solids and citric acid in the juice. The only dif ference that was consistent in all four replications was a reduction in the ascorbic acid content of the juice in the low-boron trees. This treatment aver aged 49.8 mg. per 100 ml., as against 57.0 and 54.9 for the medium and high boron treatments, respectively. This response may be indirectly attributable to the boron suply, however, and more closely associated with the higher level of phosphorus in the low-boron trees. This latter relationship was found to exist under orchard conditions when the leaf phosphorus was increased without changing the boron status of the trees (5). The literature on boron nutrition shows several cases with various plants of a lack of growth response to a dif ferential supply of this element between the limits of deficiency and toxicity levels. On the basis of this limited study with Valencia oranges, citrus seems to be no exception to that rule. Apparently normal trees can be grown with very limited applications of boron if it is supplied at frequent intervals. Likewise, applications of boron in amounts which produce mild toxicity symptoms do not seem to interfere ap preciably with the functioning of the plant. The evidence presented is the first to show the relatively small effect of rather large variations in the boron content (maximum range 16 to 386 p.p.m.) of citrus on growth, fruiting, and the concentration .of other mineral elements in the leaves: A similar range (30 to 305 p.p.m, boron) in mature V~

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TABLE 1 TilE .RELATION OF BORON LEVEL TO CROSS-SECTIONAL AREA OF THE TRUNK, AND DRY WEIGHT AND MINERAL CO~IPOSITION OF LEAVES OF YOUNG _ VALENCIA ORANGE TREES AT DIFFERENT INTERVALS OF A THREE-YEAR . CULTURE PERIOD. TREES PLANTED APRIL 28, 1947 . Boron ~1ean trunk Mean leaf Percentage of leaf dry matter P.p.m. in leaf dry matter Sampling date . applied X-section weight and -leaf age (p.p.m.) (cm. ') (mg.) N p K Ca ~fg B Mn Cu Zn Fe 9-4-47 0.00 . 3.08 193 2.82 0.150 1.84 2.95 0.395 41 42 8 5 . ri1onths 0.50 3.07 176 2.78 0.171 1.77 2.98 (}.360 90 47 9 2.00 2.73 193 2.71 0.136 1.79 2.98 0.352 117 41 8 er. 7-10-48 0.00 4.89 274 2.91 0.164 2.86 2.42 0.194 16 33 8 74 2:: 6 months 0.50 272 i44 44 9 80 .., 4.75 2.89 0.156 2.84 2.55 0.194 ::r: 2.00 4.49 330 2.81 0.161 2.92 2.52 0.202 386 46 8 64 > z 8-5c49 0.01 14.56 364 2.26 0.133* 1.84 2.68 0.288 25 31 14 47 83 '-' ::0 6 months 0.50 14.77 358 2.25 0.121 1.72 2.84 0.242* 93 34 14 41 83 M 2.00 13.89 389 2.15 0.112 1.99 2.70 0.267 263 30 13 43 76 C .., ::r: 8-30-49 0.01 414 2.15 0.178** 1.84** 2.61 0.512** 17 24 14 29 66 M ?.' 1 month 0.50 365 2.23 0.147 2.13 2.69 0.442 58 35 14 24 68 ::0 2.00 379 2.12 0.146 2.15 2.20H 0.444 130 25 14 25 65 M U'J >,:j 9-29-49 0.01 458 2.44 0.175** 1.82** 2.90 0.524** 20 28 13 29 0 z 2 months 0.50 419 2.38 0.140 2.04 2.74 0.435 67 32 15 36 U'J M 2.00 431 2.34 0.137 2.25 2.50lHC 0.421 158 29 14 36 .., 0 12-5-49 0.01 18.13 506 2.30 0.157* 1.65 2.98 0.450* 24 44 13 29 tJ:I 4 months 0.50 18.18 454 2.35 0.133 1.68 2.98 0.400 78 45 14 28 0 ::0 2.00 18.36 477 2.31 0.138 2.03** 2.55-lC-lC 0.398 168 36 13 33 0 z 6-8-50 0.01 20.52 304 2.35 0.119 1.48** 2.46 0.349 25 43 12 34 5 months 0.50 20.67 314 2.20 0.117 1.80 2.54 0.312 104 38 12 33 2.00 20.87 326 2.27 0.114 1.78 2.41 0.351 262 40 11 32 L.S.D. between any two means @ 0.05 N.S. N.S. N.S. 0.020 0.22 0.27 0.040 2.7 N.S. N.S. N.S. N.S. @ 0.01 0.027 0.30 0.36 0.053 3.6 Significant difference. c.:> .... Highly significant difference.

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32 FLOHIDA STATE HORTICULTURAL SOCIETY, 1950 lencia orange leaves was found in a recent survey (3) of 75 commercial orchards in the major citrus producing areas of the United States. Summary Young Valencia orange trees were grown for three years in large outdoor sand cultures on complete nutrient solu tions that varied differentially only in the amount of boron. Three rates of boron were applied to single-tree plots. The plots were replicated four times . No difference in tree size resulted from the differential treatments. Rather large differences in the boron content of the leaves were induced. The low-boron plants showed mild foliage deficiency symptoms during the second year but not in the first or third years of growth. The high-boron plants showed slight leaf symptoms of toxicity throughout the three-year period. Mature leaves showed virtually no differences in mineral composition other than the 10to 24-fold difference in boron. Phosphorus tended to be present in slightly greater concentration when boron was low. Young leaves showed this same rela tionship with phosphorus in a more pronounced manner. When the boron sup ply was low, potassium accumulation in the leaf was retarded and magnesium accumulation accentuated. The rate of calcium accumulation was depressed at the highest boron level. These differ ences appear to diminish as the leaf approaches maturity. The only consistent difference in the quality of the fruit produced during the third year was a slight reduction in the ascorbic acid content in the low-boron cultures. LITERATURE CITED 1. CAMP ; A. F., nnd FUDGE, B. R. Sonic symp toms of citrus malnutrition in Florida. Fra . Agr. Exp . Sta. Bull. 335. 1939. 2. REED, H. S. A Physiological study of boron deficiency in plants. Hilgarclia 17: 377-411. 1947. 3. REUTHER , W., SM IT H, P. F., and SPECHT, A. W. A comparis on of th e mineral composition of Val e ncia orange l eaves from the major producing areas of th e United States. Proc. Fla . . Staw Hort. Soc. 62: 38-45. 1949 . 4 . SMITH, P. F. and REUTHER , W. Observations on boron defici enc y in citrus. Proc. Fla. State Hort . Soc. 62: 31-37. 1949. 5. SMITH, P. F., REUTHER, W., and GARDNER, F. E . Phosphate fertilizer trials with oranges in Florida. II. Effect on some fruit qualities. Proc. Amer. Soc. Hort. Sci. 53: 85-90. 1949. 6. SMITH, P . F., and REUTHER, W. The response of young Valencia orange trees to differential boron supply in sand culture. Plant Physiol. 26: (In Press) . 1951. RIO GRANDE GUMMOSIS Its Occurrence in Florida Citrus J. F. L. CHILDS Bureau of Plant Industry, Soils, and Agricultural Engineering, United States Department of Agriculture Orlando In 1945 G. H. Godfrey published an article entitled "A Gummosis Associ ated with Wood Necrosis" (4), in which he reported what was presumed to be a new disease attacking citrus trees, prin cipally grapefruit, in the Rio Grande Valley of Texas. This disease is considered by the Valley growers to be their most serious citrus disease. In November of 1949, in company with Dr. Godfrey and his former assist ant Mr. Carl Waibel, I saw the Rio Grande Gummosis disease on the Ex periment Station grounds at Weslaco. Several days later symptoms of the same disease were seen on grapefruit trees in the Coachella Valley area of California. Subsequently Mr. Waibel informed the writer that he had assisted Dr. Fawcett in identifying the disease

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CHILDS: HIO GRANDE GUMMOSIS 33 in California ~nd that Dr. Fawcett was satisfied that Rio Grande Gummosis is distinct from the virus disease, psorosis. This has an interesting bearing on the early history of gummosis in Florida. Upon returning to Florida, many gummosis lesions were examined by the writer and were found to resemble closely the trouble seen in Texas and California. Later Mr. Waibel visited Florida and confirmed the suspicion that Rio Grande Gummosis is none other than the old Florida Gummosis disease under a new name. Without going into the complete history of this disease, it. should be noted that the earliest detailed description of gum mosis in Florida was published by Faw cett in the Agricultural Experiment Station Report of June 1907 (1). Later he published other reports of his work on gummosis, in one of which (2) he explained how to distinguish gummosis from foot-rot (Phytophthora citroph thora), and from leprosis (Florida scaly bark disease). Recognition of the importance of gummosis disease in Florida reached its high point when Rhoads and DeBusk published their bul letin in 1931 (5). After that date little was published, and gummosis eventu ally came to be regarded as merely a name to describe any disturbance giv ing rise to a little gum. This situation is the result of a peculiar set of circumstances and events. In the first place some of the symptoms of gummosis are remarkably like certain symptoms of foot-rot on the one hand and like certain symptoms of psorosis on the other. As a result gum mosis has been confused with these dis eases. In addition gummosis has been known under other names such as "tears," and "gum disease," which led to confusion. Uncertainty as the iden tity of the causal organism has been detrimental to understanding gunimosis. When Fawcett reported (3) that he had isolated Diplodia natalensis from gum mosis lesions and that Diplodia caused more profuse gumming than any other isolate many were led to infer that Diplodia was the cause of the gumming when neither foot-rot nor. psorosis seemed to fit the case. Although Faw cett reported that Diplodia inoculations did not form typical gummosis lesions (3), that fact was overlooked by many. It seems as though it was overlooked by Fawcett himself for when he later recognized the disease in California he did so under the nayp.e of Rio Grande Gummosis. However Diplodia infec tions cause the wood to become dark grey to black in color, which contrasts sharply with the buff and orange color typical of citrus wood infected with gummosis. Also, Diplodia readily at tacks sour orang/causing profuse. gum~ ming, but Stevens (6), Rhoads (5), and Godfrey (4) all agree that soii:r orange is highly resistant to if not immune from gummosis disease. As a result of these facts there is basis for consider able doubt that Diplodia is more than a secondary invader of gummosis lesions. SYMPTOMS OF GUMMOSIS IN TEXAS AND FLORIDA The symptoms of the gummosis dis ease as seen in Texas parallel closely the symptoms in Florida and are in close agreement with those described by Fawcett in 1907. On that basis, the disease as found in Florida, Texas, and California can safely be regarded as a single disease for which the name gum 0 mosis, as originally used in Florida, should take precedence. Gummosis lesions may be active at any time of the year and on lemon trees they appear to be active almost con tinuously. On grapefruit the. period of greatest activity seems to be early spring. This yea'r (1949-1950). the dis ease was especially active from Decem

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34 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 her through February, perhaps because of an unusually warm winter and an early spring. Since lemons ceased to be grown commercially in Florida (due in large part to gummosis, although foot-rot is usually blamed), gummosis is most frequently seen affecting ma ture grapefruit trees. Any point on the trunk and larger limbs may be at tacked. The following table (Table 1) adapted from Rhoads and DeBusk (5) indicates the relative susceptibility of several citrus species to gummosis. TABLE 1. The Susc e ptibility of Several Species of Citrus to Gummosis as Indicated by the Presence and Ext e nt of Lesions. Adapted from Rhoads and D e Busk (Joe.cit.) . SPECIES OF CITRUS Lemon Grapefruit Sweet Orange Tangerine Sour Orange SUSCEPTIBILITY RA TING Most s u s ceptible Very su s c e ptible Moderately susceptibl e Very resistant Most resistant There are roughly speaking two types of lesions, depending on age and man ner of infection. In appearance young infections are very similar to young infections of foot-rot, i.e., a small quan tity of light-colored gum oozing from a small spot where the bark appears slightly wet or water-soaked. However, the cambial surface of the wood be neath the gumming spot lacks the brownish-yellow stain characteristic of foot-rot infections. Frequently (at least on grapefruit trees) small woody galls or outgrowths from the wood un der the bark are found associated with young gummosis infections. These out growths are usually green in color due to the presence of chlorophyll presum ably stimulated by the disease. So far as is known such outgrowths are not found associated with foot-rot, with Diplodia infections, or with the virus disease, psorosis. Usually there is no bark scaling at the time of first gum production, although the bark may split slightly. Young lesions appear to heal by sloughing off a thin scale of dead outer bark, exposing a buff-colored scar. This occurs shortly after gumming ceases. The scar consists of callus tissue generated by the bark. Healing is only temporary, for later in the year, or per haps the following year, gum exudes again, and additional scales of bark slough off, thus enlarging the lesion and repeating the cycle. In the course of re peated gumming and scaling, the lesions enlarge to cover a considerable area, and in time the wood becomes exposed. The direction of greatest enlargement is parallel to the axis of the trunk or limb and not around the circumf~rence, as is the case with the psorosis. In addition, psorosis lesions always look ulcerated and give no appearance of healing, even temporarily. In foot-rot lesions the bark is killed down to the wood and is subsequently sloughed off as a single slab, and any healing that occurs takes place at the margins of the lesion. In older infections of gummosis the disease usually has penetrated deep into the wood, and as a result it is often necessary to chisel through a half inch or more of healthy wood to expose the gummosis infection. When thus ex posed the cut surface of the infected wood is seen to be a buff or buckskin color usually banded and bordered with a salmon-orange color that deepens in shade when exposed to the air. The banded appearance is due to the wood of certain growth rings having become impregnated with gum. Frequently gum collects in lens-shaped pockets that cause the outer layers of wood . and the bark to become raised as though by large blisters. When these "gum . pockets" break through to the surface larg . e quantities of semi-liquid gum are re leased. The cavities vary in size, some being half an inch thick by an inch wide by two inches long, and the in ternal walls are usually covered with small gall-like protuberances that some

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CHILDS: lUO GRANDE GUMMOSIS 35 times enlarge to the point of filling the cavity. The disease appears to pene trate long distances through the wood so that gum pockets may be formed at a considerable distance from the nearest bark lesion. The importance of the gum pockets in diagnosing gummosis disease was noted by Fawcett in 1907. A summary of the more characteristic symptoms of gummosis is presented in Table 2, in comparison with the symp toms of foot-rot and psorosis, the two diseases with which it is most frequent ly confused. Causal Organism At present the cause of gummosis must be considered as unknown since there is no published record of typical symptoms of gummosis having been produced by inoculation with a pure culture of any organism or with a virus. The causative agents of foot rot, psorosis, and Diplodia infection have been satisfactorily disposed of as possible causes of gummosis, and many years ago in Florida Fawcett (3) showed that uninfected mechanical in juries to citrus trees did not gum. It is true that certain chemicals stimulate gum formation, but the remainder of the symptom picture is lacking, i.e., cycles of gumming and healing, gum pockets, and certain other features have not been found associated with chemi cally induced gumming. The only other causal agent worth consideration at this time is the one reported from Texas. Godfrey found what he describes as an actinomycete-like fungus associated with the disease. Up to the time I talked with him in 1949 he had been unable to obtain this organism in pure culture, but he has been able to cause the dis ease on numerous occasions by inocula tions with chips of diseased wood. Al though this organism is suspected, its causal relationship has not been proved. Control From the citrus grower's point of view, emphasis on the identity of the causal organism is somewhat academic. What he wants to know is how the dis ease spreads and how it can be stopped. Old gummosis infections in Florida and in Texas indicate that pruning wounds are the most important point of entry of gummosis, with other bark injuries only slightly less important. In Texas the disease is sometimes referred to as "wet-back" disease because it is so often associated with bark injuries caused by Mexican fruit pickers, "wet backs," who frequently climb the trees when picking fruit. Whether the or ganism can penetrate through unin jured bark is not known, though judging from some of the young lesions seen in Florida this year, it seems that it can. However, young infections that take place through the bark are easily cared for, and do not present the same hazard as infections arising in the wounds that TABLE 2. DIFFERENCES AND SII\IILARITIES IN THE SYl\!PTOI\IS OF FOOT-ROT (PllYTOPIITHORA CITROPll TlIORA), GUl\lMOSIS (CAUSE UNKNOWN), AND PSOROSIS (VIRUS). Disease Symptoms Foot-rot Gummosis Psorosis Gumming Heavy Very heavy Practically none Bark Sloughing Entire bark thickness Outer scales Outer scales Gum Pockets in Wood None Common None Color of Affected Wood Yellow to Brown Buff with Salmon Bands Brown Causal Organism Fungus Unknown Virus

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36 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 result from cutting off large branches. The practice has been to remove large branches by sawing them off as close to the trunk as was convenient and to let the stump heal over as best it could. Even under the most favorable circum stances, it takes several years for a large pruning wound to heal over. In the meantime, the wound is open to infection by gummosis and other diseases. All pruning wounds three-quarters of an inch in diameter or larger should have a wound disinfectant applied to them. For this purpose few materials are as satisfactory as Avenarius or Red Arrow carbolineum. In addition, any wound 1 inches or larger should have a coating of water-emulsified asphalt applied to the carb0Unem dressing one week afterwards. Such treatment will maintain the wound surface in a dry, fungus-repellant state until the bark has healed over it. Painting the surface of an old wound will not eradicate gummosis from deep in the wood. Old infections will have to be excavated with a chisel or gouge. All the discolored diseased wood should be removed and, after several days of drying, the surface should be treated with carbolineum and asphalt emulsion as in the treatment of new wounds. When gummosis disease has been estab lished a long time the grower will have to determine whether the tree is worth the expense of treatment. Young lesions are easily excavated and heal over in a short time if proper dressings are applied. However gummosis lesions that have apparently healed over with out adequate treatment are still alive and will break out with renewed activ ity at a later date. The proper treat ment of wounds is an excellent example of the adage that an ounce of preven tion is worth a pound of cure. BIBLIOGRAPHY 1. FAWCETT, H. S. Gumming of Citrus . In Fla. Agr. Exp. Sta. Ann. Rpt. ( 1907 ), p. xlvi-xivii. 2. ----------, Gummosis. In Fla. Agr . Exp. Sta . Ann. Rpt. (1910), p . xlix-li. 3. ----------------, Gumming. In Fla. Agr. Exp. Sta. Ann. Rpt. (1912 ), p. lxxvii-xcii. 4. GODFREY, G. H. A Gummosis of Citrus Associ ated with Wood Necrosis. Science 102 ( 2640): 130, 1945. 5. RHOADS, A. S., and DEBUSK, E. F. Diseases of Citrus in Florida. Fla. Agr, Exp. Sta. Bulletin 229 (1931 ), p. 66 74. 6. STEVENS, H. E. Gummosis. Fla. Agr. Exp. Sta. Ann. Rpt. (1914), p , lvii-lxxiv . PRESENT STATUS OF SPREADING DECLINE R. F. SUIT AND H. W. FORD Citrus Experiment Station Lake Alfred The investigation of spreading decline of citrus in Florida has been in progress for the past five years. During that time information on the varieties of citrus and the rootstocks on which the decline was found has been reported ( 1). In addition, the effect of the disease on the tree (1) and the rate at which the decline spreads in the grove have been discussed (1,2). At one time it was con sidered that the citrus nematode (Tylen chulus sem.ipenetrans Cobb) might be associated with spreading decline (1) but subsequent results showed that the citrus nematode was not the causative agent for typical spreading decline (2). In the experimental work on virus trans mission, no evidence was found to indi cate that the disease was caused by a virus (1,2). Although preliminary in vestigations did not indicate that a fungus was responsible (1), it appears that the trouble may be the result of a fungus infection of the fibrous roots that gradually spreads through the grove from root to root (2). Numerous ex periments with various types of possible control measures were conducted but no

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SUIT AND FORD : SPREADING DECLINE . 37 successful method for the control of the disease was found (1 , 2 ). Considering all of the information al ready obtained and the additional results accumulated since the last report in 1949, what is the present status regard ing spreading decline? Spreading decline occurs on all vari eties of oranges, grapefruit and tan gerines budded on rough lemon, sour orange , sweet orange or grapefruit root s tock. The presence or absence of the disease on other kinds of rootstocks has not been determined. The number of groves in which typical spreading decline is ' present are located as follows: Polk County-74, Orange County-8, High lands County-5, and Hillsborough Coun ty-2, making a total of 89 groves. There are a number of groves in which spread ing decline occurs that we do not have on our list. Those trees which have spreading de cline show sparse foliage and reduced growth but do not die. The trees with in the decline area all show the same degree of decline and a distinct margin i s evident with the decline trees on one side and the healthy tree s on the other. The disease gradually spreads from the declining trees to the adjacent healthy trees. Rate of Spread To determine the rate of spread of the disease, the groves are mapped each year after the spring flush of growth. The yearly maps are then compared to obtain the number of trees that become diseased during any given ye a r. Since the decline spreads at the margin of the diseased area, the rate of spread is obtained by dividing the number of trees that become diseased by the num ber of trees on the margin of the de cline area. The results obtained from 25 selected groves are presented in Table 1. These data show that con siderable variation occurred in the rate of spread in the variou s groves from 1945 to 1950. The marginal rate of TABLE L Yearl y V a r ia ti o n i n Rat e of Increase of Spr e adin )( De c li ne i n 25 Groves. R a t e of Spread' Grov e 1 9 451946194719481949Aver a g e 194 6 1 94 7 1948 1949 1950 1 1.6 2 1.2 3 1.0 4 1.1 5 0 . 2 6 0.7 7 1.0 8 0.3 9 0.5 10 0.6 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Average 0 . 8 1.1 0.3 1.4 0.6 0.8 0.7 1.4 1.7 1.8 1.5 0.9 2.0 1.0 0.8 0.7 1.1 1.3 0.6 1.6 1.1 0.7 2.3 0.7 1.9 1.9 1.1 1.1 2.0 1.8 0.9 1.4 1.1 2.5 out 2.8 1.0 0.9 2.7 2 . 3 2.3 2.7 1.3 1.5 1.6 3.0 0.5 1.3 out 2.8 0.8 3.8 2.3 2.0 1.5 2.0 out 2.2 0.6 4 . 7 0.5 5.2 1.5 3.0 1.8 1.1 0.5 2.7 0.5 3.2 8.3 4.1 0.9 2.6 1.0 2.7 0.6 1.5 1.0 1.6 0.6 4.3 0.1 2.7 1.5 1.4 1.4 1.2 1.8 1.5 1.2 1.5 0.8 1. 3 1.8 1.3 1.7 1.7 2.1 2.6 2.3 1.1 1.4 5.7 2.5 1.8 1.7 1.3 1.1 2.2 1.6 1 In c r ea s e in numb e r o f disea se d tre es p e r tr ee on th e margin of th e d e clin i ng ar e a. TABLE 2. Increase in Numb e r of Diseased Trees in Affr c t e d Grov es During a Five Year Period. Grov e 2 3 4 5 6 7 9 10 No. Diseased Tr e e s I 94 5 1950 In cre a se 13 138 125 77 244 167 164 511 347 121 296 175 21 199 178 29 142 113 51 152 101 66 249 183

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38 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 spread varied from 0.1 to 8.3 trees with an average of 1.6 for all groves through out the five years. Six groves showed an average rate of spread of over 2.0 for the five-year period. The greatest average yearly spread was in 1948-49 when the rate was 2.7. In general. spreading de c line can be expected to move outward 1 or 2 trees per year. To demonstrate the total number of trees that may become diseased over a period of years, the data obtained from 8 groves was examined. These groves had been mapped six times and complete records for the five-year period were available. As is shown in Table 2, the number of diseased trees in the groves varied from 13 to 164 when they were mapped in 1945. By 1950, the number of diseased trees varied from 138 to 511. Grove No. 4 showed the largest increase but also had the most diseased trees in 1945. However, the increase in number of diseased trees was not always greater in the groves that had more diseased trees at the beginning of the experiment as illustrated by com parison of the data from groves 5 and 6. Apparently the conditions in some of the groves . were more favorable for the de velopment of spreading decline. Causal Agent Spreading decline appears to be the result of a disorder of the fibrous roots of the tree. No evidence has been found to indicate that the disease is caused by a virus. Although the citrus nematode is present in a number of groves in Flor ida, it was not found in groves which have typical spreading decline. Two kinds of fungi can be consistently isolated from the fibrous roots of the diseased trees. One is a Fusarium sp. and the other has not yet been identified. It is probable that the spreading decline is caused by a fungus infection of the fibrous roots. A number of experiments are in progress to determine whether either of these two fungi may be the causal agent. One characteristic of a Fusarium dis ease is the ability of the fungus to pro duce a toxic wilt-inducing material when grown in Richard's solution. This toxic material adversely affects the host when the disease occurs under natural condi tions. In the case of spreading decline, a toxic material was obtained from water extracts of the fibrous roots, the woody portion of larger roots and the leaves from diseased trees. This toxic material caused the wilting of citrus cuttings within 48 hours and of tomato . cuttings in 24 hours. Extracts from healthy trees did not cause a wilting of the cuttings. Fusarium cultures No. 16, 29 and 35 obtained from diseased trees were grown in Richard's solution for two weeks and the filtrate tested for wilt inducing ability. The filtrate from culture 29 was more toxic than that from the other two cultures in causing a wilt of citrus cuttings. Since . a wilt inducing material can be extracted from the diseased trees and is produced by the growth of the fungus in Richard's solution, it is indirect evidence that the spreading decline may be the result of the infection of the fibrous roots by a Fu sari um. Experiments have been conducted and are in progress to determine the effect of soil from a spreading decline area, healthy grove soil and virgin soil on the growth of rough lemon seedlings and young Duncan grapefruit trees on rough lemon rootstock; In one series of tests, the seedlings in the decline soil show a reduction in growth com pared to that of the seedlings in the other soils. It has also been found that Tendergreen beans and sunflowers de velop a greater amount of root rot when grown in soil from a spreading decline area than occurs when they are grown in . . soil from the healthy part of the grovei . Both of the ,. previously . men

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SUIT AND FORD: SPREADING DECLINE 39 tioned fungi have been isolated from the diseased bean and sunflower plants. In one instance, velvet beans were used as a cover crop in the spreading decline area of a grove. The stand was poor and about 50 percent of the plants showed root rot. A number of other kinds of plants will be tested for their susceptibility to root rot when grown in soil from a spreading decline area . If a satisfactory test plant can be found, it will be possible to evaluate the effec tiveness of the various soil treatments more rapidly than can be done by grow ing citrus seedlings. Control Measures Considering the evidence obtained, it is doubtful if a treatment can be found which will rejuvenate those trees that have spreading decline. Therefore, to control spreading decline, two problems should be considered . How can we stop the spread of the decline in a grove? What soil treatment should be used before the area is replanted? In some cases, growers have attempted to con trol spreading decline by removing those trees which were visibly diseased. Within a few months those trees at the margin; which appeared healthy when the other trees were removed, began to show typical decline symptoms. Before decline can be properly con trolled it will be necessary to know the number of trees affected with the dis order which are located in advance of those trees showing visible symptoms. Since plant pathogens often affect plant metabolism a measurement of the rate of respiration of citrus leaves or roots should show whether differences exist in ' : _ metabolic activity between appar ently healthy trees in advance of the decline margin. A difference in meta bolic activity might be indicative of the spread of the pathogen. The rate of respiration of fibrous roots ft.om healthy trees and decline trees was measured using 40 root tips from each tree. The root tips were suspended in a 2 percent glucose solu tion and placed in a Warburg respirom eter at 33 C. where oxygen measure ments were made at 10 minute intervals for a period of one hour. The rate of oxygen absorption by the roots secured from three typical groves is shown in Table 3. It was evident in every meas urement that the rate of respiration of the decline trees was lower than the respiration rate of the healthy trees in the same grove. The data also indicate that in the majority of the groves tested there was a successive increase in respiration rate from the decline area up to and including the third healthy tree beyond the decline margin. In every grove the respiration rate was highest for the third or fourth healthy tree beyond the decline margin. The rate of respiration of healthy trees be yond the fourth tree was slightly lower than the third tree but usually higher than the first or second healthy tree. It was also interesting to note that the respiration rate was practically the same for all healthy trees in the same grove located more than 4 trees beyond the visible margin of spreading decline. Although these data are preliminary . in nature it would appear that the decline TABLE 3. Respiration Rate of Fibrous Roots from Decline Tree s and from Con se cutive Healthy Trees in Advance of the _ Margin, . Condition . . Microliters of Oxygen per Hour Tree No . of Tre e Grove 1 _ Grove 2 Grov e 3 0 Decline 15.3 23.4 22 . 5 1 Healthy 18.6 26.6 . 30.3 2 Healthy 22.5 3 Healthy 34.3 38.4 41.2 4 Healthy 33,1 5 Healthy 31.2 31.8 . 30.6 . 6 Healthy 29.2 7 Healthy 28.8 33.8 30$ 8 Healthy 28.8 9 Healthy 31.3 29.1 29.0

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40 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 casual factor had an initial stimulating effect on the respiration rate of the third or fourth healthy tree. It would seem logical, therefore, that as the invasion became more severe the respiration rate was reduced as illus trated by the lower metabolic activity of the first and second healthy tree. Respiration studies are being con tinued and additional indices evaluated as an aid in the interpretation of the significance of metabolism in the third and fourth healthy trees beyond the decline area. The activity of the catalase enzyme in the leaves has been used occasionally as an indication of the rate of metabolic activity. Sixty leaf discs were selected from each tree and ground while fresh with a mechanical mortar. Catalase was determined in Heinicke tubes rotated in a constant temperature water bath. The amount of catalase was ex pressed as the cubic centimeters of oxygen generated in 90 seconds when the sample was mixed with hydrogen peroxide. The catalase activity of the leaves secured from one grove is shown in Table 4 although the same general relation held for other groves that were tested. In general, there were greater variations in catalase measurements of the leaves than were apparent in the respiration rate of the roots. These differences may have been due to the greater experimental error in the catalase procedure. However, it is significant that in every grove tested the third or fourth healthy tree beyond the decline margin had the most catalase present. Since a preliminary study of the physiology of the citrus tree has in dicated some variation up to the fourth visibly healthy tree ahead of the margin of the decline area, it is probable that, if all of the diseased trees plus four or five good trees around the area were removed, the disease could be eliminated. Assuming that this procedure would be effective, what would be the result if this had been done in 1945 in the eight groves which we have studied? As is shown in Table 5, the number of diseased trees in every grove is greater now (1950) than the number TABLE 4. The Catalase Activity of Grapefruit Leaves from ConsPcutive Trees Across the l\-far~in of the Decline Area. Condition Catalase as cc. of 0., Tree No. of Tree Released in 90 Sec. 1 Decline 15.7 2 Decline 20.2 3 Decline 17.1 4 Healthy 30.7 5 Healthy 34.0 (i Healthy 35.7 7 Healthy 30.4 8 Healthy 29.9 !) Healthy 29.3 10 Healthy 30.2 11 Healthy 28.3 12 Healthy 28.5 TABLE 5. Hypothetical Loss of Trees hy Pulling to Prevent SprPad Compared to Actual Loss by Unchecked Spread of Decline. Trees in 1945 Trees in 1950 Grove Decline Pulled Total Decline 2 13 99 112 138 3 77 97 174 244 4 164 174 338 511 5 121 133 254 296 6 21 105 126 199 7 29 68 97 142 9 51 82 133 152 10 66 88 154 249 of decline trees plus a margin of four trees that would have been removed in 1945. Arrangements have been made to try this procedure in three groves this winter. It will be two or three years before definite conclusions as to its effectiveness can be obtained. It is possible that a chemical barrier

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SUIT AND FORD : SPREADING DECLINE 41 maintained in a grove might stop the spread . of the decline. Such a barrier would need to kill the roots to eliminate root contact and have some disinfecting action on the soil. Preliminary tests with cyanamid, formaldehyde and D-D ( dichlorapropane-dichloropropene) indi cated that a formaldehyde solution should be effective as a barrier. The barrier would be examined periodically and when the roots started to grow back into the treated soil, the chemical would be applied again. A system of barriers at different distances ahead of the inargin has been established in nine groves. Formaldehyde at 3 gallons to 100 gallons of water was injected into the sciil at the rate of 2 gallons of solu ~ tiori per 5 feet of barrier. It is possible that some results will be obtained by 1952. If either or both of the above men tioned measures of pulling marginal trees or using a chemical barrier will stop the spread of the decline, then the problerri remains as to a satisfactory treatment for the soil so that replants will . grow properly. In February, 1948, two . blocks of spreading decline trees were removed and the soil treated with D-D at 400 pounds per acre. The treated areas were replanted with budded trees and records on growth are being ob tained. After two years, the trees planted in the treated soil are making better growth than those in the non treated soil. The data from one of the blocks are shown in Table 6. The D-D is . not a good fungicide, but at the rate used has some fungicidal effect. In another experiment rough lemon seedlings . were planted in decline and virgin soils which had been treated With . D-D, formaldehyde and ethylene dibromide•in December 1948. 111 : 0cto ~ her 1950; 6 out o( , lSseedlings , in t . he non-treated decline soil had died _ _ and the remaining plants had , grown aQout two-thirds as much as . the seedlings in the treated decline soil or in the non treated or treated virgin soil. Final records have not been made but there does not appear to be any significant difference in the growth of the seed lings whether in treated decline soil, or in the non-treated or treated virgin soil. TABLE 6 . EFFECT OF SOIL TREATMENT WITH D•D ON GROWTH OF YOUNG TREES. Caliper Height Spread Tre a t e d Soil Non-Treated Soil 1.91 in. 5.80 ft . . 5 . 69 ft. 1.75 in. 4.93 ft . 5 . 18 ft. To obtain additional information on various materials that might be effec tive as a soil treatment, a series of tests were started in May 1950. A total of 56 materials are in the test. It may be possible to obtain some information by the spring of 1951. Summary Groves in which spreading decline is pre s ent in Florida are located in Polk, Orange, Highlands and Hillsborough counties. Over a five year period ; the average rate of spread of the decline irt all groves mapped was 1.6 trees per tree on the margin of the decline area . During the same period, the number of trees with the disease increased from 2 to 9 times in different grove s . Spreading decline appears to be the result of a fungus infection of the fibrous roots. A Fusariuin sp. and . ari unidentified fungus have been consis tently isolated from the roots of dis eased trees. •. Indirect evidence obtained by means of the "wilt test" has indi cated that a Fusarium may be the casual agent . . Tests on the respiration and . catalase activity of rootlets and leaves of dis . (lased antl healthy citrus . trees indicated that the ais'ea:se niay extend to the third or fourth : healthy tree ahead . of the

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42 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 margin of the decline area. Any at tempt at controlling spreading decline by removal of the trees should also in clude at least four healthy tree~ ahead of the margin. Rough lemon seedlings have made better growth when the decline soil was treated prior to planting with D-D, formaldehyde or ethylene dibromide in pot experiments. Field tests with D-D at 400 pounds per acre appear promis ing. LITERATURE CITED 1.. Sun, H. F. Spn~ading decline of citrus in Flor ida. Proc. //lorit/11 State Ilnrt. Soc, 60: 17-2:J, 1947. 2, SuIT, H . F, anrl L. C. KNORR, Proi:rt•ss rt'port on citrns d
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THOMPSON AND GRIFFITHS: PURPLE MITE CONTROL 43 TABLE 1. A RELATIONSHIP OF COPPER DEPOSITS ON LEAVES TO PURPLE MITE INFESTATIONS SIX MONTHS AFTER THE COPPER APPLICATIONS. Copper Spray Plots Combinations Applied May 6 5 23 Copper-W. Sulfur 1 2 20 Copper-Oil 2 8 26 Copper-W. Sulfur 1 19 Copper-Oil 12 80 Copper-W. Sulfur 3 21 Copper-Oil 13 31 Copper-W. Sulfur 4 22 Copper-Oil Dates of Summer Oil Sprays June 3 June 16 July 14 July 14 Aug. 4 Aug. 4 Copper Deposit 3 Percent Leaves on Foliage Infested with mcg/cm 2 Av. Purple Mites Av. 1.6 10 1.9 1.8 6 8.0 3.7 67 8.0 3.4 51 59.0 1.7 23 2.7 2.2 27 25 3.7 73 4.3 4.0 55 64 2.5 2 1.2 1.8 10 6.0 3.3 64 4.1 3.7 63 63.5 2 1 1.8 1.9 1 1 5 11 4.7 4.8 11 11 1 Neutral copper (34<;; metallic Cu) (i!; 3-100 + wettable sulfur 12%-100. ' Proprietary copper-oil emulsion @ 2 gallons-100. ' Copper analyses made by C. R. Stearns, Jr. Parathion has been used as an insec ticide for the control of scale insects and mealybugs during 1949 and 1950 and some growers are of the opinion that it is a factor in increases of purple mites. . Following the summer sprays for scale control it was found that pur ple mites were more numerous after an application of parathion than after an oil spray. Parathion killed the active mites. but it did not kill the eggs nor did the residue on the leaves and fruit remain toxic long enough to kill the young mites as they hatched. By com parison, an oil emulsion spray killed the active mites as well as the eggs. Thus, if there is an infestation of purple mites in the grove when an application of parathion is made, it may be expected that mites will again be present within a week or two after the application. The parathion situation may be fur ther complicated by the use •Of almost all other sprays or dusts. In the summer of 1950, observations at seven loca tions in Polk County demonstrated some of the interactions to be expected when different spray programs are used. The data are presented in Table 2. From these data and other data not shown here, it would seem that the use of copper, zinc and sulfur are major factors influencing summer and fall purple mite infestations and that para thion is a minor factor. The average purple mite infestations were highest in plots where copper, zinc, lime and wettable sulfur had been applied as a post-bloom spray and followed with sulfur in the summer. Where nothing but sulfur sprays or sulfur dusts were used throughout the season the mite populations were higher than where parathion was used and much higher than in the unsprayed trees. The light est infestations were in the plots sprayed with oil emulsions and in the untreated plots. However, it should be

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44 FLOHmA STATE HOH.TICUL TURAL SOCIETY , 1950 TABLE 2. SUMMER PURPLE MITE INFESTATIONS FOLLOWING VARIOUS SPRAY PROGRAMS IN SEVEN GROVES. P e r cen t Infested Leaves Summer 1 2 3 4 5 6 7 , Post-Bloom . Application Application Aug. Au g . July July S e pt . July July Averages 23 15 26 20 16 2 13 Copper, zinc, lime, sulfur Oil emulsion 2 6 2 0 2 2.4 Copper, zinc, lime, sulfur Parathion 1 36 24 26 32 10 25.6 Copper, . zinc, lime, sulfur Sulfur 53 23 66 90 58.0 sulfur Parathion 1 24 24.0 , sulfur Sulfur 39 46 37 28 37.5 No sprays or dusts 16 5 2 10 0 2 1 5.0 1 Wettable sulfur 10-100 was c ombin e d with parathion. noted that during the spring, all plots, including the untreated ones, were heavily infested. Although spray residues may affect purple mite infestations, the type of weather still appears to be the domi nant factor in influencing widespread mite populations. Lime-sulfur, wet table sulfur, sulfur dust and compounds of copper and zinc have been used over wide areas in the state for many years and generally heavy infestations have been the exception rather than the rule. Miticides If purple mites continue to be a prob lem during . the spring and summer months it will be desirable to have a miticide that can be used safely during periods when succulent foliage is present . and during warm weather. This problem will be intensified by the sub . stitution of other scalicides for oil emulsion. During the past two years several new insecticides have been tested for the control of purple mites and they, along with the DN compounds, are discussed in the following paragraphs. DN Dry Mix which contains 40 % dinitro-o-cyclohexyl phenol, is still one of the most satisfactory miticides on the market but it is not safe to use when there is succulent foliage present or . when the weather is hot. DN-111, a preparation containing 20% dinitro-o-cyclohexyl phenol, 1 dicy clohexylamine salt applied at 1 pounds per 100 g a llons is as effective as DN Dry Mix at 2/3 of a pound. It cart be combined with the same type of spray materials that are used with DN Dry Mix and is not so toxic to young foliage as DN . Dry Mix. DN-111 is slightly more expensive than DN Dry Mix per 100 gallons of dilute spray but 'it is within the economic range for grove use. In 1947, Thompson (4) reported that Neotran, which contains 40 % bis (p~chlorophenoxy)-methane, was effec tive in killing purple mites. Repeated tests have been made with this material and it has been found to be effective at 1 to 2 . pounds per 100 gallons of spray. 1t appears to be compatible with all of the materials, including Iime sulfur; now used as sprays on citrus in Florida. It is one of the few miticides on the market at the present time that is effective when mixed with highly alkaline solutions. No foliage injury has been observed with this material . when it wa s applied in the spring on succulent foliage or during the summer months. The limiting factor of Neotran is the cost, which at the present time is approximately 80 cents per pound. Thus, at two pounds per 100 gallons the cost

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THOMPSON AND GRIFFITHS: PURPLE MITE CONTROL 45 of 100 gallons of dilute spray would be $1.60 or $8.00 per for a 500 gallon tank. Another promising material, desig nated here as K-6451, is a wettable pow der containing 50 percent chlorophenyl, p-chlorobenzene sulfonate. This ma terial does not result in a high initial kill, but 7 to 10 days after the applica tion, very satisfactory control has re sulted. The period of control with this material was somewhat longer than that obtained with DN Dry Mix. However, the period of control with K-6451 was not as long during the warm spring and summer months as it was during the cool months from November to Febru ary. The minimum concentration for good control has not been determined but it will probably be 11/:.! to 2 pounds per 100 gallons. It appears to be similar to DN in its compatibility with spray materials. To date no injury ha 3 been observed where it was applied to succu lent foliage or when it was applied dur ing the summer months. Taste tests of the fruit as well as further experi mental work on compatibility and con trol will be needed before this material is released for the public use. At the present time there has been no informa tion released on the probable cost of this material. Aramite, a 15 percent mixture of beta-chloroethyl-beta-(p-tertiary butyl phenoxy)-alpha-methyl ethyl sulfite, has shown some promise as a safe miticide to use during the spring and summer months. On an average this material has not been as effective as DN, Neo tran or K-6451. Aramite, like all other materials tested, was not as effective during the summer months as it was during cooler weather. It was found to be compatible with most materials used as sprays on citrus, but it was not tested with highly alkaline materials. No injury has been observed on succu lent foliage where this material was used nor has there been any injury following sprays applied during June, July or August. The present cost of Aramite is also comparatively high. Other materials tested in a limited number of experiments included a 50 percent mixture of . p-chlorophenyl phenyl sulfone and EPN, a material containing 27 percent of ethyl par:i., nitrophenol, thionobenzenephosphonate. Both of these materials appeared safe to use on succulent foliage and during warm weather but further tests are necessary to determine their effective ness as a miticide. lt is interesting to note that where the sprays were applied in April or May the period of control was not so long as where the same materials were applied in November. It is quite possible that one of the factors which shortened the period of control was reinfestation of mites from adjacent properties. The plots sprayed in April and May were adjacent to blocks that were heavily infested with mites and there were indi cations in some experiments that adult mites migrated into these plots within 5 to 6 days after the applications. In one experiment no living mites were observed 3 days after a thorough appli cation of an effective miticide. In com parison, the untreated plots were 100 percent infested. Four days later an other examination was made and an average of 9 percent of leaves on the sprayed trees were infested with adult mites. It would thus appear that mi gration of adult mites took place be cause mites cannot develop from the egg to the adult stage within four days. In two other experiments conrlncted during the spring months it was found that adult mites made their appearance 5 to 6 days following an effective miti cide where no mites were found 3 days after the application. In Table 3 are recorded some of the results obtained with the most promis ing materials tested. It is desirable

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46 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 TABLE 3. COMPARISONS OF CONTROL OF PURPLE MITES WITH VARIOUS MITICIDES. M ate rial s a nd Concent ratio n s in Pounds per 100 Gallons Sprayed November 7 DNDry mix K~6451 Neotran Aramite Sprayed November 11 DN Dry mix K-6451 Neotran Aramite Sprayed Janu ary 11 DN Dry mix K-6451 Neotran Aramite No treatment Sprayed April 3 DN Dry mix K-6451 Neotran Aramite No treatment Sprayed April 17 K-6451 K-6451 No treatment .66 lbs. 1.50 " 1.50 " 1.50 " .66 lbs. 1.50 " 1.50 " 1.50 " .66 lbs. 1.50 " 1.50 " 1.50 " .66 lbs . 2.00 " 2.00 " 2.00 " 1.5 lbs. 2.0 . " to do : further experimental work with all of . these new miticides, not only to test their effectiveness, but also to test their safety on foliage and fruit. .Timing and Applic;:ittion of Sprays . . ' ~ The period of control of purple mites does not depend entirely on the miticide used. One of the cardinal prerequisites to obtaining a long period of control is to apply the miticide before a high pel"Figures Express Perc e nt Infe sted Leaves PreNov. Dec. D ec. Jan. Feb. Spray 12 1 30 19 10 92 94 94 77 Nov. 1 15 18 14 15 Jan. 5 0.2 4.1 0.0 0.0 Nov. 28 0.0 0.0 0.0 3.0 J an. 16 32 0.0 42 13.0 34 0.0 48 0.6 36 28.1 0.0 o;o 0.0 1.2 Dec, 22 0.0 1.4 9.5 0.1 0.0 6.5 0.4 2.1 21.5 4.8 12;2 81.5 Jan . 7 Feb. 10 0.8 3.8 33.5 1.2 10 . 2 19.4 0.0 2.9 32.1 1.1 8.3 50.3 Feb. 4 6.2 1.9 13.8 19.0 40.0 F e b . 28 5 . 0 1.5 22.5 10.5 26.0 March April April April May 5 May 23 30 7 13 27 33 21 47 4 5 1.7 2.5 0.0 6.0 5.0 April April 13 21 10 12 33 0.0 0.0 45.0 1.0 0.0 0.0 1.0 15.0 0.0 19.1 0.0 .4 0.0 4.1 1.2 27.1 15.0 30.0 May May May 23 2 8 2.0 o:o 77.0 18.0 0.0 88.0 45.0 53.0 97.0 60.0 2.5 29.0 61.0 57.0 centage of the leaves become infested. This i s illustrated in the following dis cussion. Although it is now well known that parathion is not an . outstanding materi al for the control of purple mites, light infestations in four plots were kept at a low level for two months where parathion was included in a dormant spray at 1 pound of 15 % material per 100 gallons of mixture.

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THOMPSON AND GRIFFITHS: PUHPLE i\UTE CONTROL 47 When the application was made about 2 percent of the leaves were infested, whereas two months later an average of 8 percent of the leaves were infested in the parathion plots as compared to 32 percent infested leaves where para thion was omitted. The parathion had killed the few active mites, and since there were very few eggs present at that time, the mite population did not build up in those plots until May. The intensity of the infestation at the time of spraying influenced the degree of infestations at a later date. Thus, in experiments where duplicate plots were used, and where there was a dif ference of 20 to 30 percent in the original infestation at the time of spray ing that difference was still apparent at the conclusion of the experiment although the level of population had been substantially reduced by all treat ments. This was true in 88 percent _of the duplicate plots. For instance, on January 3, Plot A had 18 percent of the leaves infested and the duplicate, Plot B; had a 43 percent infestation. Three months after the application, Plot A had 4 percent of the leaves infested compared to a 35 percent infestation in Plot B. This comparison is made to stress the importance of treating groves in October or November when the mite population is at a low level, and treat ing again in January or February. Mite populations will thus remain _at a low level through the late winter and spring months when grove conditions are likely to be unfavorable for spray ing . because of dry weather and the presence of succulent foliage. If dusting is practiced it is especially important to make the application be fore the mite population reaches a high level. If a high percentage of the leaves are infested when a dust is applied, a second application should be made within a week or ten days to bring the numbers down to a point where a rea sonable period of control can be obtained. Thorough coverage is of prime im portance. None of the miticides are considered fumigants and direct con tact is necessary for satisfactory con trol. The type of coverage that is usually made for rust mite control is not thorough enough for purple mite control. Special care should be taken to cover the tops of the trees where the heaviest infestations are usually found. LITERATURE CITED 1. HOLLOWAY, J. K., CI,IAS. F. HENDERSON and HoRACE V. McBuRNrn. Population increases of citrus red mite associated with the use of sprays containing inert granular residues. ]our. Econ. Ent. 35 ( 3): 348-350. 1942. 2. THOMPSON , W. L . Cultural practices and their -influence upon citrus pests . ]our. Econ. Ent . 32 ( 6 ): 78 _ 2-789. 1939. 3. THOMPSON, W. L. Progress report on purple mite and its control. Proc. Fla. State Hort. Soc. 57 : 98-110. 1944. 4. THOMPSON , \V. L. and J. T. GRIFFITHS, Jn. New insecticides and their application. on citrus . Proc . . Fla. State Hort. Soc. 60: 86-90 . 1947. 5. THOMPSON W. L. Combined control of scale insects and mites on citrus. Fla. Agri . Exp. Sta . Ann. Rept. 71-73. 1948 :

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48 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 FLORIDA'S STAKE IN PLANT QUARANTINE ENFORCEMENT AVERY S. HOYT, Chief Bureau of Entomology and Plant Quarantine Washington, D. C. As everyone knows, injurious insects and plant diseases constitute serious obstacles to agricultural production. This seems to be true the World over. Fortunately or unfortunately the de structive organisms that cause greatest losses in one part of the World may not occur in others. This feature of their distribution gave rise many years ago to efforts in various parts of the World to set up restrictions aimed at protect ing the agricultural industry of one country from plant pests known or be lieved to occur in another. These re strictions which we call quarantines were in effect in some parts of the World long before the United States first gave consideration to its need for similar plant-pest protection. By 1912 when this country first enacted legisla tion for this purpose many injurious insects and plant diseases had found their way here and had become estab lished. As fruit and vegetable produc tion is particularly vulnerable to attack by these organisms, many States were united in urging upon Congress the need for action. The State of Florida, because of its tremendous production of tl'iese articles, was and continues to be one of the l&aders in urging the need of some means of screening the arrival here of additional plant pests. Florida jg particularly vulnerable because of climate, crop specialization, geographi cal location, and proximity of serious insect pests and plant diseases within easy reach of Florida ports by air and water. In 19i'2 Congress passed the Plant Quarantine Act authorizing the Secre tary of Agriculture to promulgate rules and regulations to safeguard the im portation into this country of nursery stock, fruit, and other plant products. It has been the policy of the Depart ment to take such action on a biological basis. Care has been taken to avoid the use of this authority in furtherance of economic or competitive conditions. Quarantines that have been promul gated have been aimed at specific sub jects and have been accompanied by minimum restrictions consistent with the objective of protection from insect pests or plant diseases not known to occur or to be widely distributed within this country. The restrictions issued under this legislation by the Secretary of Agriculture have varied during the years, depending to some extent on the . nature of the material which formed the large percentage of the imports, upon information with respect to pest risks, and upon the advisability of the application of methods of treatment to safeguard the importations. Much of the information on which plant quarantines have been put into effect through this authority by the Secretary of Agriculture has been ac cumulated by the Bureau of Entomology and Plant Quarantine. In the case of plant diseases the basic information has frequently been furnished by the Bu reau of Plant Industry, Soils, and Agri cultural Engineering. In the case of every foreign plant quarantine the ob jective has been to get the most accu rate knowledge possible with respect to the distribution of the insect or disease, ways in which it might be transported, materials on which it would be most likely to be carried, the possibility of destroying the organism through the

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HOYT: PLANT QUARANTINE ENFORCEMENT 49 application of treatments at destina tion or port of entry, and the probable damage likely to occur in this country in the event of its introduction. In general the policy on which quarantines have been established has been to con sider the biological necessity to exclude a specific plant pe s t and then to provide such restrictions on the importation . of the plants or parts thereof which serve as the host as will most adequately pro tect domestic agriculture. With the passage of the Plant Quar antine Act the responsibility for deal ing with foreign quarantine problems was placed on the Federal Government. Plants and other restricted commodi ties imported into this country are con sidered to be in foreign commerce until actually arrived at the point of destina tion. It has been held by legal advisers of the Department that the States do not have authority over such commerce until delivery to the ultimate consignee. At that point under the State police powers the State plant quarantine offi cials have authority to make inspections and take appropriate action. As a result of research, much of which has been done by the Bureau of Entomology and Plant Quarantine, means have been developed to destroy injurious insects on various types of commodities through the use of com modity treatments. These methods of treatment are required as a condition of entry for many different kinds of plants and plant products. Tempera tures, both hot and cold, for specified period s of time, poison gases, and vari ous insecticidal dips may be required. These methods of treatment may be prescribed in some cases after inspec tion as a precaution and in ::iome cases are required as definite conditio113 of entry. In the case of fruits originating in countries where fruit flies of various species are known to occur, the time temperature treatments are required as a condition of entry. There are 3 gen eral procedures under which these treatments may be applied: (1) At port of entry under the supervision of rep resentatives of the Bureau; (2) in the country of origin and at the present time this is applic a ble only to Mexico where arrangements have been made whereby representatives of the Bureau may do such work at the expense of the exporters, and (3) the application of the treatment in transit. It has been found that the temperature and the exposure duration are not the same for all species. More extreme temperatures and longer time intervals are needed for some. These commodity treatments are effective when properly applied and with experience it has been possible to simplify and standardize equipment and procedures to make their application more effective and less costly. One of the serious problems is our inability to recognize the symptoms of, or to control, that class of diseases which is caused by the presence of a virus. In the inspection of nursery stock entering the United States it has been found impossible through inspec tion at the ports of entry to be sure as to the presence or absence of a number of virus diseases. It was primarily be cause of the need to strengthen our pro tection against virus diseases accom panying imported nursery stock that led to the revision of Quarantine 37, the Nursery Stock, Plant, and Seed Quarantine, a few years ago providing the requirement of growing the material for a specified period of time in post entry detention to permit inspection during one or more growing seasons. It is recognized that postentry pro cedures leave something to be desired. It is not the best procedure to bring plants into this country , establish them in our soil, and then await the possibility that they may have brought some seri ous infestation or plant disease. It is

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50 FLORIDA STATE HORTICULTURAL SOCIETY, 19,50 believed, however, that inspection dur ing the growing season offers the best chance to detect the presence of virus diseases in plants. It is hoped that it may be possible to arrange that our inspectors may examine the material in the country of origin. Inspection of the growing material in the nurseries abroad and the rejection there of ma terial which appears to threaten our welfare would seem to be more practi cable and effective. If the means and the trained men were available to in augurate such a program it would be necessary that there be an invitation from the countries involved to make the inspections within their borders. Some progress has been made in this direc tion. Inspectors of the Bureau have visited a few countries on specific errands involving the inspection and application of treatments for the safe guarding of materials destined to be shipped to this country. It is believed the recognition of the advantages of this method of procedure will grow and it is hoped that by this means a satis factory substitute for the present sys tem of postentry inspection may be developed. A step in the direction of more effec tive international cooperation was taken when the United States was represented at the recent International Conference on Plant Quarantine Regulations con vened by the Netherlands Ministry of Agriculture at The Hague. This initial conference resulted in a draft of an international agreement which is now before the countries concerned for con sideration. Its prov1s1ons include: Statements of Purpose and Responsi bility; Supplementary Agreements under the Convention; Establishment of National Organization for Plant Pro tection; Requirements in Relation to Exports; Requirements in. Relation to Imports; International Cooperation; Amendment of Convention; Settlement of Disputes; Treatment of Non-adher ing Countries; Ratification and Ad herence, and Effective Date. From par ticipation in this Convention it is be lieved the United States should benefit. The question has been asked whether this would mean that the Federal in spectors would have to accept certifi cates from officials of other countries. The answer to this is no. We do not have to accept their certificates now and the proposed standardization would not modify this authority. To my knowledge no agency of the Federal Government has sought to influence decisions of the Department of Agri culture based on biologically sound re quirements for imported plant material. From the standpoint of this country it is believed international discussions such as this International Agreement contemplates may afford us a chance to establish relations with other countries which it is hoped may lead to the op portunity for our inspectors to work with their inspectors in the nurseries from which shipments are made to the United States. It is our hope that this would furnish some first-hand infor mation about the conditions surround ing the material which is offered for entry into this country. In recent years plant pests have been transported over long distances as never before through the movement of airplanes. Planes taking off in one part of the World and landing in another all between sunrise and sunset means that living insects may be transported and become established as has not been the case with slower transportation. Florida has occasion to fully under stand the consequences in terms of dangers of plant pest distribution due to the enormous increase which has taken place in international air trans portation. The burden of inspection which has fallen on the Florida State Plant Board in Florida and on the

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HOYT: PLANT QUARANTINE ENFORCEMENT 51 Bureau of Entomology and Plant Quar antine throughout the country is in direct proportion to the expansion in this activity. In the first 9 months of 1950, 14,500 planes from foreign ports were inspected in the State of Florida by State and Federal inspectors cooperating. There are numerous instances of the long-distance transportation of living insects by means of airplanes. Evidence is abundant that some injurious species have been established in distant parts of the World through this means. It seems reasonable to believe that the danger of the long-distance dissemina tion of injurious insects through air travel is likely to increase unless definite measures are taken to prevent. With this objective experiments are be ing conducted to develop insecticides to be applied to interiors of airplanes. Planes from Hawaii are sprayed be fore departure from the Mainland, care ful inspection is being made of foreign planes on arrival at the airports in this country, and representations have been made to the agricultural officials of other countries looking toward their adoption of precautions which might be of protection to them as well as to us. Florida is interested in the status of the diseases of citrus known as mal secco, quick decline and tristeza, and of the infestations of the citrus blackfly in Mexico and the oriental fruit fly in Hawaii. In Mexico work against the citrus blackfly has been carried on in coopera tion with the Mexican Department of Agriculture and with committees of growers organized in some of the prin cipal fruit-growing States of that coun try which have actively participated in the suppressive program. Infestation was found early in 1950 as close to the border as Matamoros just across the Rio Grande from Brownsville. This was a light infestation found on one tree on a property within a few doors from the bus station which leads to the belief that the insect may have reached that point in connection with bus travel from interior points of Mexico. That infestation is believed to have been eradicated and no recurrence has been found to date despite frequent and care ful inspections. Bus travel is inter rupted at the border as the vehicles themselves do not cross. The question whether the insect may be carried as a hitch-hiker on traffic crossing the line, however, is under investigation. This involves the possibility of spraying such vehicles in connection with their crossing and search is being made for a suitable spray. Infestation now occurs in the City of Monterrey where spraying is being car ried on at all points where living citrus blackflies are known to occur. Other infested areas in Mexico where sup pressive measures are being applied include Victoria and one or two points between Victoria and Monterrey; also in the vicinity of Valles in the State of San Luis Potosi about 300 air miles south of the border where rather heavy infestations of the citrus blackfly have occurred over a period of several years. At that point a Bureau spray program is in progress on selected properties to demonstrate that fruit production can be restored if proper sprays are applied at the right time. On the West Coast the infestations which were found in the vicinity of Guaymas and Empalme have been sub jected to several spray applications. In this area it will be recalled the first suppressive measures were put into effect by the fruit growers of Arizona and California who contributed funds and sent their own men to supervise the program. In this initial effort the Bureau cooperated by determining the limits of infestation to the northward in cooperation with the Mexican Depart

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52 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 ment of Agriculture. The number of infested properties has been steadily reduced as well as the intensity of the infestation. In Cuba the citrus blackfly was found to be readily controlled by parasites. These same insects taken to Mexico and liberated there have not proven to be equally effective. It will be recalled that there was an infestation of the citrus blackfly in south Florida on Key West a number of years ago. Resort was not made to natural control at that time as it was deemed desirable to com pletely eradicate the infestation if pos sible and after a spray program of some duration in which the Bureau coop erated with the State Plant Commis sioner, it is believed the infestation was completely wiped out. Parasites were imported into Mexico during the season 1948-49 from Malaya. There was diffi culty in making these introductions be cause the infestations were on citrus in that country. Because of the danger of bringing citrus canker infested material to Mexico the procedure was to take potted citrus trees from Mexico to Malaya, there infest them with the citrus blackfly, then introduce the para sites, cage the infested plants and ship by water. Little success attended these efforts, perhaps because of the long period of time involved. In the season of 1949-50, parasites were collected in India. In this instance it was possible to secure infested non-citrus leaves carrying the parasites. These were shipped at frequent intervals by air and a large amount of the material came through successfully. Sufficient time has not yet elapsed to permit an evaluation of the effectiveness of these beneficial insects. It would very great ly lessen the concern of the fruit grow ers of this country if biological control of the citrus blackfly in Mexico should prove to be effective. With respect to the oriental fruit fly situation in the Hawaiian Islands, a very comprehensive research program was undertaken in the beginning of the fiscal year 1950 with funds made avail able by the first session of the 81st Congress. The work was divided into five main projects: (1) Biology and habits of the fruit fly (2) Treatment of agricultural prod ucts grown in infested areas so that they may be transported safely into uninfested areas (3) Search for insecticides that will kill the insect ( 4) Large-scale control and eradica tion studies (5) Biological control The work in these lines of investiga tion has been vigorously prosecuted. The importations of beneficial insects have been very encouraging. A num ber of the imported species have been recovered from various parts of the Islands showing that they have become definitely established and at some points the parasitization has reached an encouraging level. Active coopera tion in the studies directed against the oriental fruit fly is being received from California and from Hawaii. The Cali fornia State Department of Agriculture and the Citrus Experiment Station of the University of California have been actively cooperating. They have loaned men to this undertaking and accepted responsibility for certain activities associated with the general program. The Board of Agriculture and Forestry of Hawaii and the Hawaiian Experi ment Station are also valued coopera tors. The Pineapple Research Institute and the Hawaiian Sugar Planters Asso ciation Experiment Station are also giv ing valuable assistance. Airplanes leaving Hawaii for the Mainland are given preflight inspection and are also sprayed in an effort to

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GRIFFITHS, STEARNS AND THOMPSON: CONCENTHATED SPRAYS 53 prevent hitch-hiking fruit flies. Care ful inspection and treatment of prod ucts moving to the Mainland are re quired. California has been carrying on a trapping program in order that if the fly should find its way there the infestation would be discovered while still in the incipient stage. The results of this trapping program have thus far been negative in California. Plant quarantine policies and pro cedures have been undergoing rather frequent and rapid changes. Progress in the development of insecticides, ad ditional information as to the distribu tion and abundance of plant pests, and the possibility of long-distance dissemi nation all have contributed to this situ ation. In this country the State plant quarantine officials, by working to gether, have made notable progress in simplifying, coordinating, and streamlining the State quarantines and pro cedures which affect interstate ship ments of plants and plant products. Their organizations-the regional and the National Plant Boards have afforded a medium for free friendly discussion of their mutual problems. It is believed that progress in dealing with other countries is possible through similar means. Long strides in this di rection have been made in our dealings with our neighbors, Canada and Mexico. Working at greater distance there has been excellent ground work laid for further cooperative relationships with Argentina, Australia, and Holland. Better understandings lead to better cooperation. From our point of view better cooperation means fewer plant pests accompanying agricultural im ports and that is the aim which must be kept ever before us. POSSIBILITIES FOR THE USE OF CONCENTRATED SPRAYS ON CITRUS IN FLORIDA JAMES T. GRIFFITHS, C. R. STEARNS, AND W. L. THOMPSON Florida Citrus Experiment Station Lake Alfred During the past few years, spray machines have been developed for ap plying concentrated sprays to deciduous fruit trees. The purpose of such sprays was to apply the required amount of the active ingredient to the tree with a minimum amount of water. By reducing the actual gallons of spray per tree the cost of application may be decreased both by eliminating the haul ing of water and by reducing the time required to refill the spray tank. If the spray mixture is concentrated four times the ordinary strength, then there is a saving of 75% in the amount of w~ter hauled, and a similar amount of time saved in filling the tanks. With concentrated sprays such a low volume of fluid is delivered per tree that no run-off or dripping occurs. The pur pose of this paper is to present results on the use of concentrated sprays on citrus in Florida.* The first concentrate type sprayers to be used on citrus in Florida were tested by King and Griffiths (2) in 1947. Two machines (Buffalo Turbine and Hessian Microsol Generator) were tested in the control of the American grasshopper in citrus groves. These machines gave very poor insecticide distribution on the tree. In spite of this, relatively satis factory grasshopper control was ob tained. However, it was concluded that For those readers who desire informntion concerning the history and tl,cory of concentrated sprays reference is suggested to a thesis. by R, M. Pnitt ( 6).

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54 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 this type of machine would not be practical for the control of sedentary citrus pests. At the start of the 1949 spray season, a Hardie mist sprayer** was loaned to the Citrus Experiment Station. This machine is powered by a 45 h.p. gasoline engine. Air is delivered to only one side at the rate of approximately 20,000 cubic feet of air per minute and at a velocity of 110 miles per hour. The pump capacity is 18 gallons per minute, and the pressure is maintained at ap proximately 400 pounds. The principles involved in the design of this machine were developed at Cornell University ( 4,5,6). The basic design is such that the air is driven up into the tree, and the desired spray particle size is pro duced by the use of high pressures. Also in 1949, the Speed Sprayer Com pany began developmental work on modi fied nozzles to be used in a Speed Sprayer (Model 36) for the delivery of concentrated sprays. In contrast with the Hardie sprayer, a Speed Sprayer delivers approximately 44,000 cubic feet of air to two sides or 36,000 to one side, and the velocity varies between 90 and 105 miles per hour. It is pow ered by a 110 h.p. gasoline engine. A centrifugal pump is employed to deliver spray solution at a pump capacity of 150 gallons per minute at 65 pounds pressure. A number of other concentrate spray ers are being offered for sale in other parts of the United States. One of these, the Lawrence Mist-o-Matic Sprayer, was tried in the summer of 1950. The distribution of spray mate rials appeared to be satisfactory in the tops and on the off-sides of the trees, but the lower 6 feet of the tree adjacent to the sprayer were not covered. This machine will require considerable modi0 0 Mist sprayer as defined by Pratt ( 6) is a sprayer to be used for the application of concentrated sprays. fication in order to make this a practical sprayer for use in citrus groves. During 1950, some caretakers have successfully applied double concentra tions of toxicants at half gallonage with the conventional nozzles in a Speed Sprayer. Such semi-concentrates rep resent a compromise between dilute and concentrated sprays, but they represent a trend in the direction of concentrated mixtures. The work reported here deals with experiments conducted during the 1949 and 1950 seasons using the Hardie sprayer and the Speed Sprayer. In most cases, the spray was applied at one eighth the gallonage and at six timeR the concentration normally used. This meant that three-fourths as much mate rial was being applied per tree as with a dilute spray. Previous work on apples had indicated that less material was necessary when no drip occurred (1,3). Results Mite Control.-During the 1949 and 1950 seasons the two concentrate spray machines were compared with a dilute Speed Sprayer in an orange grove near Auburndale. The dormant spray (zinc, DN, sulfur), the post-bloom spray (cop per and sulfur), and summer and fall sulfur sprays were applied with this machinery. The summer spray for scale control was an oil emulsion applied by a hand machine. Careful checks were made of purple mites and rust mites throughout the two years. There was no significant difference in the control of these pests that could be attributed to the use of concentrate sprays. In similar small scale tests, rust mite and purple mite control was as satisfactory with concentrated as with dilute sprays. Scale Control.-Three rather extensive scale control experiments have been per formed. In 1949, a parathion experi ment was carried out in a grove near

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GRIFFITHS, STEARNS AND THOMPSON : CONCENTRATED SPRAYS 55 Auburndale. Parathion was used as a concentrated material and compared with both a 1.3 percent oil spray and a dilute parathion spray, both of which were ap plied by hand as well as by Speed Spray er. Duplicate plots were used in all experiments. The concentrated material was ap plied with the same nozzle settings in all plots, but the machines were driven at three speeds, which resulted in more gallons being applied per tree at the slower speeds. The concentration of in secticide was so regulated that the com parable amounts of parathion were ap plied per tree. Half of the plots sprayed with concentrate had the p a rathion con centration arranged so that only three fourths of the standard quantity was used per tree. The results of this experi ment are shown in Table 1. In one of the Hardie plots, purple scale control was unsatisfactory, apparently due to nozzle stoppage and to the fact that distribu tion of the insecticide was poor. It was concluded from this experiment that there was no significant difference in control caused by the use of dilute as compared to concentrate sprays, by the use of the Hardie Mist Sprayer versus Speed Sprayer, or by the use of 25 per cent less parathion as compared to the usual amount of parathion. Another scale control experiment was performed at Lake Placid in 1949. This compared dilute sprays in a Speed Sprayer with concentrated sprays in both the Hardie Mist Sprayer and the Speed Sprayer. The standard applica tion was supposed to consist of 28 gal lons per tree of a 1.3 percent oil spray. All sprays were applied at the rate of 1 mile per hour. Three nozzle sizes were used in both the Speed Sprayer and the Hardie Sprayer. This was done in order to vary the amount of water applied per tree. The concentration of oil used in the Speed Sprayer was arranged so as to deliver the same amount of oil per tree as would be applied if a 1 percent oil were used at 28 gallons per tree. For the Hardie Sprayer, three oil concentrations were used which were equivalent to the oil TABLE 1. SUMMARY OF PURPLE SCALE CONTROL IN GROVE AT AUBURNDALE ON JUNE 30, 1949. Sp ee d Gal. / Lb s . Para% Mortality Mi. / Hr. Tr e e thion / Tr ee Avg. of Two Plots 1.0 5.0 .032 98 1.0 5.2 .073 99 Speed Sprayer 1.5 3.5 .049 99 Concentrate 1.5 3.3 .071 100 2.0 2.3 .042 99 2.0 2.3 .064 97 1.0 3.0 .031 93 1.0 3.6 .054 80 1.5 2.7 .042 98 Hardie Sprayer 1.5 2.9 .068 97 2.0 2.5 .052 100 2.0 2.5 . 078 97 Speed Sprayer 1.0 25.0 .062 99 Dilute 1.0 25.0 1.3% oil 100 Pressure Sprayer . 1 18.0 .041 99 Dilute 17.0 1.3% oil 99

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56 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 that would have been applied in the 1.3, 1.0 and a 0.8 percent oil emulsion, all used at 28 gallons per tree. The r . esults are shown in Table 2. The gal lons of spray per tree, the actual pints of oil per tree, and the oil deposit on the foliage is shown. There ,vere sig nificant correlations between the amount of oil sprayed per tree and the amount deposited per unit leaf area . Both of these factors were, in turn, significantly correlated with purple scale control. Red scale control was generally more satisfactory than purple scale control, and as a result, the former did not show correlation be tween the rates of application and the percent control It was concluded that the amount of oil deposited evenly over a tree was the important factor, and it appeared that it did not make any dif ference what strength or gallonage . was applied so long as sufficient oil was spread uniformly over the leaf and twig surfaces Leaf drop was not severe following this spray. However, where the . con centrate sprayer turned around the tree at the end of a row, the terminal tree had severe leaf drop. This suggested the fact that with oil sprays at least, the sprayer should come out of the grove, drive past the end tree, and then cut off the spray before turning around. This TABLE 2. A COMPARISON OF CONCENTRATE AND DILUTE SPRAYS WHEN OIL WAS USED TO CONTROL SCALE AT LAKE PLACID IN 1949. Hardie Mist Sprayer Speed Sprayer % Mortality Sp eed Oil Gal . of Pt s . Oil/ 0.il D e posit Purple Red Mi. f lu . Equiv a l en t Spray / Tr ee Tre e Mcg./Cm• Scale Scale 1.5 1.5 1.0 1.5 1.0 1.3 0.8 1.3 1.0 0.8 1.3 1.0 0.8 1.3 1.0 0.8 1.3 1.0 0.8 1.3 1.0 0.8 1.0 1.0 1.0 1.0 1.0 1.0 1.3 7.4 9.3 6.7 6.8 8.6 6.0 5.3 5.0 5.3 6.1 5.0 4.4 4.4 4.9 3.9 3.9 3.2 12.9 9.5 6.2 10.3 7.0 4.5 23.0 2.2 1.6 2.7 2.3 2.0 3.8 2.7 1.8 2 . 3 1.9 1.3 2.5 1.9 1.6 3.8 2.8 1.8 2.7 2.8 3.0 3.1 3.1 3.3 2.3 57 36 36 46 43 60 59 43 33 44 25 55 44 36 59 84 49 56 56 62 38 50 88 28 60 37 70 72 73 86 65 77 57 75 24 90 82 75 85 90 84 74 85 75 79 93 90 77 80 87 97 97 100 91 96 96 90 89 97 92 98 93 97 100 100 90 98 97 90 100 100 90

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GRIFFITHS, STEARNS AND THOMPSON: CONCENTRATED ' SPRAYS 57 would avoid excessive oil deposits and subsequent leaf drop on the end tree. In 1950, oil emulsion and parathion sprays were compared in a grove near Auburndale. These materials were ap plied by hand with pressure rigs, as dilute sprays in the Speed Sprayer, and as concentrated sprays in both the Hardie Mist Sprayer and the Speed Sprayer. The results of this experiment are shown in Table 3. The basic spray was consid ered to be 25 gallons per tree of a 1.3 percent oil or parathion at 2 pounds of 15 percent wettable material per 100 gal lon s of spray. The concentrated sprays were designed to apply equal amounts of insecticide in one set of plots and only three-fourths as much in an other set. Because of irregular delivery by both machines, no conclusions could be made regarding the rate of dosage. Purple scale control was satisfactory in all applications regardless of the method of application. There was more leaf drop following oil than parathion and more with concentrated than dilute oil, but in no instance was the leaf drop severe. Fruit Grade in Packinghouse.-In 1949, representative samples of fruit from the experimental plots at Auburn dale were checked in the packinghouse in order to compare grade as well as insect and mite injury on fruit. In this comparison, there was no difference either in grade or external quality which could be attributed to a difference in the methods of application. In other words, concentrated sprays appeared to have produced as satisfactory or as good quality fruit as that produced by dilute spray machinery. Discussion During 1949 and 1950 sufficient work with concentrated sprays has been per formed to demonstrate that they will probably be practical for use on citrus in Florida. Lime-sulfur, wettable sulfur, DN, zinc s ulfate and lime, neutral copper, oil, and parathion have all been applied successfully. However, before concenTABLE 3. PURPLE SCALE CONTROL AND LEAF DROP FOLLOWING THE USE OF DILUTE AND CONCENTRATED SPRAYS ON JULY 7, 1950 . Machine Hardie Sprayer Hand Sprayer Speed Sprayer Dilute Speed Sprayer Concentrate Gal. Oil/Tree .20 .23 .29 .36 .29 .34 .33 .29 .24 .31 .25 .33 .42 .31 % Reduction of Purple Scale 80 92 75 77 91 92 96 82 91 84 89 82 95 90 Leaf Lbs. 'lo Reduction Parathion/ of Drop• Tree Purple Scale 64 .059 80 56 ' .052 100 78 .056 97 118 .080 100 52 .060 100 40 .081 99 39 .066 97 56 .066 93 63 .067 96 33 .080 93 94 .060 95 33 .057 97 67 .0 72 95 93 .072 87 0 Based on total newly dropped leaves on 1/5 of the area under the tree on Ji1ly 31. Leaf Drop• 5 32 16 32 22 59 19 43 29 35 39 34 22 33

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58 FLORIDA STAT~ HORTICULTURAL SOCIETY, 1950 trate sprays can be generally used, a number of problems must be studied and solved. The grower will no longer be able to think in terms of how many pounds of material to use per 100 gal lons of spray. Rather he will have to know how much copper is needed on a given size tree to control melanose, how much zinc sulfate is needed on a given size tree to maintain optimum zinc levels, and how much parathion per tree is needed for scale control. As an example, it may take two-thirds of a pound of 15 percent parathion on a large grapefruit tree to control scales, and it may take only one and one-half pounds of sulfur to control the rust mites. In this case, parathion and sulfur will be used in a ratio of 4 pounds of 15% parathion to 9 pounds of sulfur. If three gallons are to be applied per tree, then 33 trees will be sprayed with 99 gallons and each 100 gallons of spray will contain approxi mately 22 pounds of 15 percent para thion. and 50 pounds of sulfur. This example shows that considerable calcu lation may be necessary in order to figure out the proper amounts of ma terial to use per tank of spray. The gallonage to apply per tree poses another difficulty. In experimental work, one-eighth the normal gallonage has been used in most cases. It may be determined subsequently that still greater concentrations will be satis factory, but, in any case, the gallons to be applied per tree will determine the amount of material per 100 gallons of spray. If the grower plans to apply 3 gallons and actually applies 3 gal lons per tree, he will not only use an extra half gallon per tree, but also this will represent a 17 percent increase in material costs. With dilute sprays, a half gallon error resulted in less than a 5 percent increase in material costs. With concentrated sprays, small errors in gallons delivered per tree will result in big differences in the amount of material applied per tree. In the case of the Hardie Sprayer, gallonage is regulated by the aperature size in the spray disc and not by the number of nozzles. Thus, the rate of delivery into the top or the bottom of a tree is also regulated by disc size. It will take considerable knowledge on the part of the operator to properly set the nozzle sizes and adjust the air flow baffles for proper distribution over the tree as well as for the proper gallonage per tree. Tall trees need larger nozzle sizes at the top and small trees need more spray concentration at the bottom. In the case of the Speed Sprayer, gal lonage can be regulated either by nozzle aperature size or by the number of nozzles. Since the number of nozzles will probably be less than one-fourth the number now used with dilute sprays, distribution will again be a problem, as it will be difficult to determine which pipe is to hold 1 and which 2 or 3 noz zles. None of these problems are insur mountable. Most can be solved by time and thought, but before attempting to use concentrated sprays a grower should be acquainted with the difficul ties involved, and he should have suffi cient information to be able to ade quately determine the amount of materi al to use and the gallons per tree to employ. The use of concentrated sprays on citrus can result in savings to the grow er. Probably less insecticide will be needed per tree. Table 4 presents sulfur deposits for one experiment where the Hardie Mist Sprayer was compared with a Speed Sprayer delivering dilute sprays. The deposits are calculated on the basis of micrograms of sulfur de posited on a square contimeter of leaf surface per pound of sulfur applied to the tree. Thus, they are a measure of the amount of sulfur which stuck to the

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GRIFFITHS, STEARNS AND THOMPSON: CONCENTRATED SPRAYS 59 TABLE 4. MICROGRAMS OF SULFUR DEPOSITED PER CM' PER LB. OF SULFUR FROM SAMPLES TAKEN FROM THREE LOCATIONS ON THE TREE. Hardie Mist Sprayer Concentrated Spray On Side Off Side Top Four 35 42 19 33 49 25 Duplicate 25 26 15 Plots 34 46 25 Avg. 32 41 21 leaf surface. The figures are for the sides of the tree adjacent to the sprayer (on side), the side between the trees (off side), and the tops. The concen trated spray deposited 25 to 50 percent more sulfur than did the dilute spray. This is similar to information from other sources (1,3). In the ca:;e of oil emulsion sprays this may not be true, but in all other instances there are definite indications that the amount of material can be reduced over that which is normally sufficient to dilute sprays. In addition to material savings, there should also be operational savings. It will no longer be necessary to use one or possibly two supply units for an in dividual sprayer. Whereas a 500 gallon tank of dilute spray will spray possibly only 25 trees, 200 trees can be sprayed with a tank of concentrate. Therefore, one supply unit should be able to supply 2 or even 3 sprayers in a single grove. This represents a saving in spray labor as well as in the use of the machinery. Summary and Conclusions Concentrated sprays have been used experimentally during the 1949 and 1950 spray season on citrus in Florida. Two machines, the Hardie Mist Sprayer Speed Sprayer Dilute Spray On Side Off Side Top 19 19 8 19 21 14 32 36 10 32 44 9 25 30 10 and the Speed Sprayer, appear to offer good possibilities for use with this type of spray. In general, one-eighth the normal gallonage was used per tree. and indications were that with the pos sible exception of oil, less spray materi al could be used per tree than with dilute sprays. In comparative trials, the control of rust mites, purple mites, scale insects, and melanose have been as satisfactory with concentrated sprays as with dilute sprays. It was concluded that the use of this type of spray should be practical on citrus in Florida. LITERATURE CITED 1. BURRELL, A. B. 1950. Concluding remarks on concentrate spraying. Proc. N. Y. St. Hort. Soc. 95: 109-113. 2. Kmc, J011N R. and J. T. GIUF'FITHS. 1948. Results of the use of concentrated sprays in citrus groves in Florida. Fla. Ent. 31 :29-34. 3. PARKER, K. G. 1950. Further studies on mist spraying. Proc. N. Y. St. Hort. Soc. 95: 105-108. 4. PARKER, K. G., R. M. PRATT, and L. R. BROWN. 1948 . Spray duster for fruit trees. Farm. Res. 14:15. 5. PRATT, R. M. 1947. The development of the new Cornell experimental spray-duster. N. Y. State Hort. Soc. Proc. 92:132-140. 6. PRATT, R. M. 1950. Investigations of fungicide deposits and fruit tree disease control by the spray-dust and mist spray methods as compared with conventional hydraulic spraying. Thesis on file Cornell University Library, Ithaca, N. Y.

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60 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 THE EFFECT OF VARIABLE POTASH FERTILIZATION ON THE QUALITY AND PRODUCTION OF DUNCAN GRAPEFRUIT JORN W. SITES Florida Citrus Experiment Station Lake Alfred Introduction For many years potash has been a major constituent in the fertilizer mix tures applied to citrus in Florida. The use of potash in modern amounts has seemed reasonable, for citrus soils in Florida are not well supplied with po tassium containing minerals. There is consequently, only a minimum supply of potassium for utilization by growing citrus trees in Florida except as fur nished in the form of fertilizer. Like nitrogen, potassium does not accumu late in these sandy soils (15) and much of that not absorbed by the roots of the trees is lost. Unlike nitrogen however, potassium deficiency symptoms are not quickly discernable under field condi tions. A number of papers have been published covering one phase or another of the work on the use of potash on grapefruit at the Citrus Experiment Station and at this time it seems de sirable to summarize these findings up to date. In this paper the symptoms which have been found to be associated with potassium deficiency in the field, and the effect of variable potash fertili zation on the internal and external quality and on production of Duncan grapefruit are presented and related papers reviewed. Literature Review A study of the literature dealing with potassium nutrition of citrus reveals that a large number of symptoms have been associated with potassium defi ciency. It should be kept in mind that in most cases these symptoms have been observed where citrus was growing under artificial conditions in pot or sand culture, and that to-date, many of these symptoms have not been observed under field conditions. The reported symp toms include dying-back of the upper most branches of the tree with the lower branches showing little signs of defi ciency (2); splitting and gumming of the twigs; scorching and excessive drop of leaves, resinous spotting, fading of the chlprophyll, and development of a bronze-yellow color (Haas 11-12-13-14). Tucking, and twisting of the leaf blades is still another symptom, ( 4). With the exception of results rep0rted by Bryan (2), the deficiency symptoms referred to were associated with orange varieties and not grapefruit. Whether all of these symptoms apply to grapefruit has not yet been established. Fruit symptoms associated with potassium deficiency have also been fairly well classified, although there are some controversial reports as to the effect on the external appearance of the fruit. Bryan (2) reported that in the few cases where fruits were produced on trees grown in pot culture, under deficiency conditions, the fruit did not appear to differ from fruit produced by trees which received potassium in suffi cient amounts. Eckstine et. al. (8) have described fruit produced under potassium deficiency as being thick-skinned, coarse, and with poor color. Fruit of small size has been reported by most workers to be characteristic of fruit produced by potassium deficient trees, (1, 6, 13, 14, 19). It is generally agreed that oranges produced by trees deficient in potassium will contain a lower percentage of citric

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SITES: POTASH FERTILIZATION 61 acid in the juice, (17, 1, 19, 13, 14). Roy (17) has further reported that Valencia oranges not supplied with potassium pro duced fruit with a higher content of re ducing sugar, a lower content of non-re ducing sugar, and a lower pH of the juice. Although it was believed for many years that muriate of potash was an in ferior source of potassium for the fer tilization of citrus, investigations by Roy (17), Cowart (7) and Bahrt and Roy (1) have shown that either potas sium sulfate or chloride are satisfactory fertilizer salts. An explanation of the background concerning these sources of potassium is necessary for it emphasizes the importance of magnesium in relation to potash fertilization practices, and to some extent the effect of magnesium on the interpretation given to some of the earlier potassium experiments. During World War I, this country was forced to depend largely on domestic sources of potassium. One of these, potassium chloride caused trouble because of the boron which it contained. Because of these experiences, combined with un satisfactory results from using muriate on other crops, especially tobacco and potatoes, potassium chloride was held in disfavor and preference was given to sulfate as a source of potassium for citrus. Kainite also used as a source of potas . sium contained appreciable amounts of magnesium as magnesium sulfate and chloride. As magnesium deficiency be came more wide-spread in Florida in the late twenties and early thirties it was found that larger applications of Kainite improved the quality of fruit on these magnesium deficient groves. Large, coarse fruit is associated with mag nesium deficiency and when Kainite was applied to deficient trees the fruit quality improved not because of the potassium but because of the added magnesium. The potash source experiment started in 1924 at the Citrus Experiment Station and continued until 1942, furnishes an other good example of the effect of mag nesium on the interpretation of results of a potassium experiment. This experi ment was initiated to ascertain the effect of muriate, sulfate and sulfate of potash and magnesia on the growth and produc tion of citrus. After several years the sulfate of potash and magnesia appeared to be a superior source of potassium. When under the direction of Dr. A. F. Camp, magnesium sulfate was added to the muriate and sulfate of potash treat ments in amounts equivalent to the mag nesium contained in the sulfate of potash and magnesia treatments, the differences between the plots disappeared (7). These examples illustrate the multi plicity of factors which are frequently involved in studying fertilizers for tree crops, some of which may not even have been considered when the experiment was initiated. Methods The experiment discussed in this paper was first started in 1921, as re ported by Ruprecht (18). At that time a block of Duncan grapefruit was laid out into six plots in such a manner that plots designated as 1, 3 and 5 received 3 percent, and plots 2, 4 and 6 received 10 percent potash in the fertilizer mix ture. In the 1924 report, Ruprecht stated that the potash treatments for plot 5 were changed so that 3 percent potash was applied in the spring, 5 per cent in the summer and 10 percent in the fall applications. During the period between 1924 and 1929 the plots were changed again so that plot 5 received 5 percent potash at each application and plot 6 received 3 percent potash in the spring, 5 percent in the summer and 10 percent in the fall applications. The plots were continued in this manner

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62 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 until 1936, at which time the original experiment was discontinued and the plots were turned over to Dr. A. F. Camp and his co-workers at the Citrus Experiment Station. In the 1930 report, Ruprecht (18) had stated that the trees in the plots re ceiving 10 percent potash were in an unsatisfactory condition. It later de veloped that the cause of this condition was due to deficiencies of magnesium, copper, zinc, and manganese, with mag nesium deficiency being especially acute. In order to correct this condi tion nutritional sprays were applied, and 4000 pounds of dolomitic limestone was applied to part of this block during 1936, 1938 and 1939, with the same potash treatments as used by Ruprecht being continued. Beginning with the fall application in 1939, plot 6 was changed to a O per cent potash treatment and the trees in this plot have received no potash fer tilizer since . that time. During the period since 1936 the trees have been on a 3 percent nitrogen program, and since 1939 have received a mixture with the formulas shown in Table 1. These mixtures are applied three times a year in February, June and October. The poundage has varied somewhat through the years, having been increased as the trees became larger. Since 1939 the poundage has varied between 15 and 20 pounds per application. Zinc is ap plied annually as zinc sulfate at the rate of 3 pounds per 100 gals. as a dormant spray. Except as noted, the plots all receive identical treatment in keeping with good grove management practice. The term interna l fruit quality as used in this paper refers to internal char;1cteristics of the fruit based on soluble solids, citric acid, and ascorbic acid content of the juice. Total soluble solids were measured with a Brix hydro meter and the readings corrected to a temperature of 17.5C. Total titratable acidity, (calculated as anhydrous citric acid) was determined by the titration of a 25 ml. aliquot juice against .3125 N sodium hydroxide solution. The ascorbic acid (vitamin C) content was deter mined by the method of Menaker and Guerrant ( 16 ) and reported as milli grams of ascorbic acid per 100 millili ters of juice. Results Visual Deficiency Symptoms under Field Conditions-Under artificial con ditions, it is possible to grow citrus trees which manifest deficiency smptoms of potassium rather rapidly. This is not true under field conditions because it is not possible to eliminate potassium from a soil as can be done with a nutrient solu tion. The increased period of time re quired for deficiency symptoms to be come evident in the field is due to several factors . The tree stores potassium, which apparently may be redistributed and re assimilated to such an extent, that the growth centers are not immediately affected. Also, a citrus tree appears to TABLE 1. FERTILIZER PROGRAM FOR THE PLUS MAGNESIUM PLOTS, BLOCK V. 1939-TO-DATE. Plot No . Formula (Percentage) N P 2 O 5 K,O MgO MnO CuO 6 3 6 0 3 1 1 & 3 3 6 3 3 1 5 3 6 5 3 1 2 & 4 3 6 10 3 1 .

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SITES: POT ASH FERTILIZATION 63 be relatively efficient in absorbing and utilizing potassium ions with which its root system comes into contact, (20). Still another factor is the reutilization of potassium resulting from the decompo sition of dropped fruit in the grove. Where potash fertilization was withheld entirely from the trees in plot 6, begin ning in 1939, no symptoms of potash de ficiency developed until the spring of 1943. Following the cold period of February 15-18, 1943, it was observed that the trees in this plot suffered more cold damage than in the plots where potassium was supplied. It was also be coming evident at this time, that the trees were showing less top growth and that the leaves were smaller, but very marked differences in tree appearance were still not evident. At about the same time, it was noted that more fruit was dropping previous to harvest where potash was withheld. This condition continued to develop and by the 1945-46 season was very evident. The trees not supplied with potash have thus far con tinued to bloom and set fruit, but begin ning sometime in July a heavy pre-har vest drop occurs which usually continues through the harvesting season. Table 2, shows the percentage of the crop which dropped during the past two seasons. The larger number of drops listed for the 1949-50 season includes fruit which was blown from the trees during the August 27th hurricane. During the past three seasons the drops have been removed regularly from the grove and since start ing this practice the trees appear to be declining more rapidly from potassium deficiency than before, indicating the potassium reserve in these trees is be coming low. It should be noted that had the experiment been discontinued before the spring of 1943, say at the end of 3 years, a flat but erroneous conclusion could have been drawn that potash fer tilization was unnecessary, Another potassium deficiency symptom which has been apparent on occasions is the tendency for the trees not supplied with potash to lose young shoots during windy periods . During the early part of March, 1950, rather high winds with light rains occurred for several days shortly after the spring flush of growth TABLE 2 . Th e, Eff e ct of V a riable Potash Fertilization on the Pr e -harvest Drop of Dunc a n Grap e fruit. Fertiliz e r Treatment N P,0 5 -K 2 O-MgO-MnO-CuO 3-6-031 3-6-33l 3-6-531 -' h 3 6 -10 3 1 P e rcentage of Dropped Fruit 0 1948-49 1949-50 45 . 7 37.3 29.5 29.5 82 . 5 67 . 2 68.5 62 . 9 •Values represent percentag e of tot a l number of fruits. Drop counts w e re mad e from Septemb e r 23 through D e c. 3, 1948, a nd from Aul(ust 31 through Nov. 25, 1 9 49. had appeared. About a week later it was observed that a number of young shoots 3 to 15 inches in length had been blown from the trees and were lying on the ground. The number of shoots blown off in each of the potash plots is re corded in Table 3. The break always occurred at the point of emergence of the shoot from the stem or branch. At the present time there are no dis tinct observable differences in tree con dition between the trees which are re ceiving the 3, 5 and 10 percent potash applications, but there is a sharp contrast between the potash fertilized trees and those which receive no potash fertilizer. Trees in the latter plot are decreasing in size, the tops are thin and the leaf stze now appears small on a number of trees. Leaf symptoms denoting potas sium deficiency are not obvious. Some twisting and tucking of the leaves of a few trees have been noted on occasion. Internal Fruit Quality. Sampling and analyses of the fruit produced by the trees in the potash plots has been con

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64 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 tinued regularly since 1939. A consid erable amount of data relative to fruit quality has been obtained, but only data for the past three years covering soluble solids, percent citric acid, solids/acid ratio and the vitamin C content is being presented at this time. This is representa tive of the data as a group and shows the difference in these juice characteristics as influenced by the potash treatments which the trees have received. Contrary to results reported by Roy (17) and Bahrt and Roy (1) in their study of Valencia oranges, the soluble solids content of the juice of Duncan grapefruit from potassium deficient trees is significantly lower in most cases than where potassium is supplied. Variations in the rate of potash application between 3 and 10 percent in most cases caused no significant difference in the soluble solids content of the juice (Table 4). The per centage of titratable acid is consistently and very sharply reduced where potash is limiting, and is increased significantly with incieasing applications of potash up to 10 percent in the fertilizer mixture (Table 4). TABLE 3. Loss of New Shoots as Affect ed by Variable Pota s h Fertilization. Fertilizer Tr ea tment N-P 2 0 0 -Kp-MgO-MnO-CnO ' 3-6-031 36 3 3 1 1/2 36 5 3 1 3 6 -10 3 1 Average Number of Shoots Lost Per Tree , 182 . 8 11.3 19.3 10.7 In as much as the ratio, (soluble solids/acid) of grapefruit juice is usual ly . the factor determining earliness of maturity for grapefruit;' the effect of potash applications on the ratio is of particular interest. The ratio of soluble solids to acid is increased where pofash is limiting, and is decreased significantly with increasing applications ' of potash. The decrease in the . ratio where the 0 lt') d, 'I' 'tj< ,-j ,-j C">-.:!'~-tj o-, CN ,-j ,-j l!:l ~i,.;.,.;,....;tN,....; CQ CQ c,:, 'tj< tCQ 0 a, M 00 M 00 M CN ~o,....;,....;o-51N CQ 'tj< 'tj< 'tj< . c,:, 00 I!:) t0 'tj< I!:) ,-j C,:,t-CNCN-.:!'O':I i,.; o o CN CN 00 CN CN -.:!' M I!:) 'tj< ,-j 00 'tj< Cl:) ooi:-=i:-=~oo tCl:) tCN ,-j o-, a, 1:-Ml!:l.:OCQCN i,.; o o a, I!:) a>l!:lO-,M-.:!'0 (N'tj000-, Cl:) MC\l-.:!'"'1'00 ,....; ,....; ,....; ,....; 00 00 CN 0 Cl:> 0 l!:l 0-, 0 u:it-ooomto-i o-i o-i o o o ,-j . Cl:) t'-'!< tl!:l ci:, M CN 0 Cl:> l!:l O Cl:! CN o-io-io-iooo ,-j . .. 0 ,-j -tj
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SITES: POTASH FERTILIZATION 65 potash application has varied between 5 and 10 percent has been significant some seasons and not in others, Table 4. In general however, the trend has been for the ratio of the juice to continue to decrease with application of potash up to 10 percent in the fertilizer mixture. The differences in the time of passing legal maturity as influenced by these fertilizer treatments for the past two seasons are presented in Table 5. The effect of potassium deficiency and variable potash application on the vita min C content of the juice, follows a pat tern very similar to that discussed for soluble solids. Where potassium is limited, the vitamin C content of the juice is significantly decreased. Varia tion in the application of potash from 3 through 10 percent has resulted in slight increases in the vitamin C content at the higher applications but the differ ences are slight (Table 4). External Quality.-The conclusions drawn by Eckstein, Bruno and Turren tine (8) that potash deficiency is mani fested by the production of large, coarse fruit are apparently incorrect. The re ports of investigators working with oranges, and a previous study by the author (19) show clearly that small fruit, with thin rind, and good texture, are produced where potash is limited. There has been no consistent difference in the proportion of Duncan grapefruit meeting the several standard U. S. Grades, due to potassium deficiency, or to variations in the level of potash fertilization. Early in the season there appears to be a rather large differential in size of fruit produced between trees which receive no potash fertilization and those which do. As the season progresses this is less apparent, probably due to the increased number of drops and the smaller number of fruit left on the deficient trees. During the past five years the fruit from the trees not supplied with potash has averaged about 0.10 inches smaller in diameter than fruit from trees supplied with potash. This is slightly less than the difference in average diameter between one commercial size. During the entire period the fruit from these plots has always been held late into the season, which probably accounts for the differen tial in size not being greater. No con sistent differences in size of fruit pro duced has been found to-date where pot ash has been applied, even though the N/K,O ratio has varied from 1-1 to 1-3.3. Production.-Table 6, presents a sum mary of the production of fruit as affected by variations in the level of pot ash fertilization during the period from 1940-41 through 1949-50. These data, based on the average production for the past nine years, show that the trees re ceiving 5 percent potash fertilization have yielded significantly more fruit than the trees receiving the other treatments. The difference between the production of these trees, and those to which 3 perTABLE 5. ESTIMATED DATES OF PASSING LEGAL MATURITY STANDARDS AS AFFECTED BY VARIOUS POTASH FERTILIZATION TREATMENTS. Treatment 1948-49 1949-50 N-P2os-K2O-MgO-MnO-CuO Estimated Difference Estimated Difference Date in Days Date in Days 3-6o_.:._3-1September 10 October 15 3-63-3-1October 2 22 December 10 56 3-:-65-3-11 /2 October 15 35 January 3 80 3~ 6-10 . -3-1 _ October 18 38 January 6 , 83

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66 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 cent potash is applied, is of greater inter est when tree condition as affected by previous treatment is considered. The reports of Ruprecht frequently _ indicated that trees receiving the 3 percent potash treatment were producing the most fruit during the period from 1921 until 1936, with the exception of one year, 1934. Further, Camp (3) reported that the 3 percent trees were affected the least by magnesium deficiency at the time that the original experiment was stopped, and corrected, in 1936. Based on previ ous performance, the highest production should be from the trees supplied with 3 percent potash. The indications are that 3 percent potash, which is equiva lent to 1 :1 nitrogen-pot11sh ratio at the rate of application used, has not been sufficient to maintain production as com pared to the higher 1 :1.6 ratio which corresponds to the 5 percent treatment. Statistically there is no significant dif ference in the production of fruit from trees receiving the O percent, 3 percent or the 10 percent potash treatment as ascertained by the nine year average. It is evident from the data, however, that the production of the trees receiving no potash has fallen off badly since the 1946-47 season, the average yield per tree since that time being only 295 pounds. The nine year average value for the trees not supplied with potash is comparatively high by virtue of the fact that these trees were producing heavily during the early part of the experiment. Discussion Under the present maturity law in Florida, earliness of maturity for grape fruit, once the juice content require ments are met, is determined in most cases by the solids to acid ratio of the Jmce. Reported earliness of maturity of grapefruit as affected by a low nitro gen to potash ratio (19), together with similar resu Its having been reported for 0 '? "' .... "' 1' CX) ..,. CX) ..,. ,!.. .... ..,. .... "' .... "' .... .; .... "" 1' .... .... .... .... 0 .... "' .... 0 LO LO 00 t-t-LO<:O t"1' t"1' Q I I I I r-1 M -r-4 ,-t 1 I I I I ::; I I I I q,o ~LO~ I I I I d' ' ' ' ' ~ 1 I I I I "'" ..,. .... """' "" .... II 'tl 0 P<

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SITES: POTASH FERTILIZATION 67 oranges has resulted in a . more wide spread use of lower nitrogen-potash ratios in fertilizer mixtures. Ruprecht reported in 1936 that based on the re sults of the potash rate experiment at that time that there appeared to be no advantage in using a ratio of nitrogen to potash higher than 1 :1. The fact that production appears to be falling off in the plots which are receiving this treat ment and that the number of drops is i.tSually higher than in either the 5 or 10 percent plots would seem to indicate that this ratio may be too narrow to obtain maximum yields at the rate of application used in this experiment. It should be emphasized that it has not been possible under the conditions of this experiment to see immediate effects from changes in potash fertiliza tion either as related to tree condition, production or fruit quality. The rather quick responses which have been evi dent in citrus from correcting zinc de ficiency, or from applications of nitro gen have not been observed as a result of variations in the applications of potash. Thus, if the lower production which has been found in this experi ment where a 1-1 nitrogen-potash ratio has been used, may be considered as in dicative of what happens under field conditions generally, the production may be decreased so gradually in a commercial grove as to go unnoticed except by the most discerning growers. The nitrogen to potash ratio in a 4-6-8-3-1fertilizer mixture applied in the fall and summer applications, followed by an 8-0-8-6-2-1 spring top
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68 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 6. CHAPMAN, H. D., BROWN, s. M., AND RAYNER, D. S. Some effects of potash deficiency and excess on orange tree growth, composition and fruit quality. Calif. Citrograph. 33 ( 7): 278, 279, 290. 1948. 7. CowART, F. F. Effect of source of potash upon fruit composition. Fla. Agr. Exp. Sta. Ann. Rept. 146-148. 1944. 8. ECKSTEIN, OSKAR, BRUNO, ALBERT, AND TUR RENTINE, J. W. Potash deficiency symptoms. 1-235. Illus. Berlin. 1937. 9. FUDGE, B. R. AND FEHMERLING, G. B. Some effects of soils and fertilizers on fruit composition. Fla. Sta. Hort. Soc. Proc. 53: 38-46. 1940. 10. Fudge, B. R. Fla. Agr. Exp. Sta. Ann. Rept. 150-152. 1946. 11. HAAS, A. R. C. The growth of citrus in rela tion to potassium. Calif. Citrograph. 22 ( 1 & 2): 6, 17, 54, 62. 1936. 12. -------------------Potassiun1 in citrus leaves and fruits. Calif. Citrograph. 22: 154-156. 1937. 13. ___ . Effect of potassium on citrus trees. Calif. Citrograph. 33 ( 11): 468, 486, 487, 488, 490. 1948. 14. --------------------. Potassium in citrus trees. Plant Physiology. 24: 395-415. 1949. 15. Kn.rn, C. D., JR, Leaching of potash from sanely citrus soils of Florida. Fla. Sta. Hort. Soc. Proc. 56: 43-48. 1943. 16. MENAKER, M. H., AND GuERRANT, N. B. Stand ardization of 2-6 Dichlorophenolindophenol an improved method for determination of vitamin C. ]our. Ind. and Eng. Chem. (Anal.) 10: (1) 25, ( 5) 269. 1938. 17. RoY, W. R. Effect of potassium deficiency and of potassium derived from different sources on the composition of Valencia oranges. ]our. Agr. Res. 70(5): 143-169. 1945. 18. RUPRECHT, R. W. Effect of potash on com position, yield and quality of the crop. Fla. Agr. Exp. Sta. Ann. Repts. 1922-1936. 19. S1TES, JoHN W. Internal Fruit Quality as re lated to production practices. Fla. Sta. Hort. Soc. Proc. 60: 55-62. 1947. 20. WANDER, I. W. (Unpublished Data). Citrus Experiment State, Lake Alfred, Fla. PANEL ON PARATHION How ARD A. THULLBERY Lake Wales Mr. President, Members of the Florida Horticultural Society and Guests: The Executive Committee of the So ciety requested that a panel be developed on Parathion to be presented at this meeting. In planning the panel the assistance of Dr. J. T. Griffiths, Mr. W. L. Thompson and Mr. Frank L. Holland was sought. Due to the keen intellect and efforts of these three gentlemen, plus the very fine cooperation of the twenty-two gentlemen seated before you, we have the panel pre pared according to the outline that has been distributed to you. These gentlemen, no doubt, are among the best qualified to speak on Parathion and its uses that could be found in the world today. They each have prepared questions which they are qualified to dis cuss intelligently. Many have prepared questions, they want others in other fields of work to answer. The opportunity has been given all of you to submit ques tions and many of you have done so. All of these questions have been sorted and grouped and will be answered by the person or persons qualified in that par ticular field. Whether or not the Moderator will allow questions from the floor will depend entirely on time. The outline covers all phases of the subject and we feel that all phases should be covered rather than too much time be spent on certain phases and others neglected. While Parathion is undoubtedly an out standing insecticide, it like all material, has its limitations. It is expected that the discussions here today will deal with the limitations as well as the outstanding qualities of this material. On behalf of the Society and personally, I wish to thank each of you gentlemen who have helped plan the panel and all of you who are participating in it. I now turn the panel over to our most efficient Moderator, Mr. Frank Holland. Moderator: We will go right to work if members of the panel are ready. Be fore we get into detailed questions there is a preliminary question which the mod

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THULLBERY: PANEL ON PARATHION 69 erator will direct to Dr. Bruce D. Gleiss ner, Entomologist with the American Cyanamid Company. What is Parathion? Dr. Gleissner: Well, Mr. Holland, Parathion is an organic phosphate. Ac tually the name Parathion is the common name for the chemical 0, O-diethyl-O. paranitro-phenyl-thiophosphate. Obvi ously, you couldn't use such a long chemi cal name so they picked Parathion. The compound was discovered in Germany but it has been more widely developed here in the United States for the control of several hundred economic species of insects and mites that attack crops grown in this country. Moderator: Thank you Dr. Gliessner. Now, to Dr . Herbert Spencer, Entomol ogist with the United States Department of Agriculture's Subtropical Fruit In sects Laboratory at Fort Pierce. In the USDA experiments, what citrus pests have been controlled with Para thion? D1. Spencer: The purple scale, Flor ida red scale, cloudywinged and citrus white flies and some of the mealybugs. The insects and mites that have not been controlled well are the purple mite and the rust mite. Moderator: What materials have you found compatible with Parathion? Dr. Sp e ncer: We have found Para thion compatible with wettable sulfur, with coppers and with oil; in fact, with most of the insecticides and fungicides except those that are very basic. We have not used it with liquid lime sulfur but there is a possibility it can be used in that combination too. . Moderator: What poundage per 100 gallons of spray gives adequate control of scale insects? Dr. Sp ence r: In our cleanup work for heavy infestations we are using 2 pounds of 15 % wettable with wettable sulfur. There is a possibility with light infestations that two applications spaced over the year with 1 pound of 15% each time may keep the infestations to , a very low level. Moderator: Thank you Dr. Spencer. The next questions will be directed to Mr. W. L. Thompson, Entomologist with the Citrus Experiment Station at Lake Alfred. To obtain scale control, is it necessary to spray trees as thoroughly with Para thion as it is with an oil emulsion? Afr. Thompson: Yes. Although Para thion has some fumigating effect it has not the same effect that you would ex pect from sulfur for rust mite control. Purple scale control was not satisfactory where a combination spray containing Parathion, copper and sulfur was applied as an outside brushing spray which was typical of the usual application made for melanose and rust mite control. The scales should be covered with Parathion for satisfactory control. Moderator: Is Parathion as effective as oil emulsions for purple and red scale control? Mr. Thompson: On a three year aver age it has been as effective as oil emul sions. However, this year where we have had an abundance of red scale, there are more red scale in the tops of the trees where we sprayed with Parathion than we have with oil ~mulsions. On the average, it has been as satisfactory as oil emulsions. Moderator: Are two applications of Parathion at 1 to 100 as effective as one application at 2 to 100? Mr. Thompson: If there is a light to medium infestation of scale to start with, two applications of 1 pound of 15 % ma terial have been as satisfactory as 2 pounds per 100 put on once. In other words, a Spring application with an other application in July or August, both with 1 pound to the 100, have been just as satisfactory and in some cases

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70 FLORIDA STATE HORTICULTUHAL SOCIETY, 1950 more so than when the application was delayed until July or August with 2 pounds to the 100 used. Moderator: Does purple mite infesta tion develop faster following a Parathion spray than where no Parathion was ap plied? Mr. Thompson: There is very little evidence to show that the effect of Para thion increases purple mite. Parathion does not kill eggs, only the active mites; therefore, when you have a rather heavy infestation of purple mites when you apply the Parathion spray, you can ex pect a comparable infestation about two to three weeks later. Two Parathion sprays applied at ten day intervals would probably control purple mites but that is really not practical. Moderator: Thank you Mr. Thomp son. The next questions will be directed to Dr. R. K. Voorhees, Associate Horti culturist with the Citrus Experiment Station at Fort Pierce. What are some of the factors respon sible for certain cases.of poor or incon sistent citrus scale control with Para thion during 1950? Dr. Voorhees: Some of the factors responsible for poor scale control with Parathion, as far as the East Coast is concerned, are: poor tree coverage for any reason, but frequently due to windy weather which also shortens the period of effectiveness of Parathion; thorough tree coverage for good scale control is frequently not obtained with the broom type hand spray guns and the boom type applicators embloyed on the coast; low or mm1mum concentrations on heavy scale infestations during any season. Moderator: How effective is Para . thion in reducing scale infestations when employed at a minimum rate in combina tion with the spring melanose sprays? Dr. Voorhees: In general, good re sults have been obtained with Parathion when combined with the melanose sprays at the minimum rate of I to 1 pounds per 100 gallons. In most cases, this has reduced light to medium infestations to the extent that only a minimum dosage had to be considered during the summer, and in some cases this second application was not needed until fall. Moderator: What are some of the main factors responsible for accidents that occurred in connection with the use of Parathion by citrus spray operators on the East Coast during 1950? Dr. Voorhees: In checking on several authentic cases of Parathion poisoning to citrus spray operators there were sev eral different factors responsible, but no single factor particularly predominate. Some of these factors were: negligence in following the recommended precau tions ; abnormally low cholinesterase level of the operator; overexposure from spraying in windy weather, high summer temperatures and especially in connec tion with heavy canopied groves with poor air circulation, and from being ex posed to Parathion too many days at any one interval. Moderator: Thank you Dr. Voorhees. The next set of questions will relate to vegetable crops, so as to continue under Item 1 of the agenda, and will be directed to Mr. Norman C. Hayslip, Associate Entomologist with the Everglades Ex periment Station at Fort Pierce. Does Parathion have a place in con trolling sweet corn insects? Mr. Hayslip: The use of Parathion on sweet corn is still in the experimental stage; however, we have conducted a series of studies using Parathion on sweet corn. It has shown up better.than any other material for the control of the corn silk fly, killing the adult stage just before the silks appear, thus preventing oviposition. On corn earworm, Parathion at 2 % strength in a dust was, in two experiments, slightly superior to 5%

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THULLBERY: PANEL ON PARATHION 71 DDT dust; at 1 % it was slightly inferior to 5% DDT dust. Cage trials indicated that Parathion has some toxic effect on adult moths of the corn earworm. The effect on the adults has not been verified under field conditions, however. Against fall armyworms, Parathion is effective at higher rates of application. That is to say, 2 pounds of 15% wettable to 100 gallons of water. Parathion also reduces the damage caused by aphids on corn. Moderator: In most cases, it has not been recommended to use Parathion on vegetables later than 30 days before har vest. How does this restriction affect the use of Parathion on vegetables? Mr. Hayslip: This question was phrased to show that such a restriction is impractical on some crops. One ex ample would be tomatoes, which are har vested over a period of 40 to 50 days; by adding 30 days to the first harvest, re sults in a period of 70 to 80 days that the tomato plants are in the field unprotected by this insecticide, leaving them exposed for a long period of time to attack by insects. Other crops of a similar nature would be peppers and, to some extent, cucumbers. The question points out the very serious need for more intelligent recommendations as to the period of time elapsing between the last treatment and harvest; and I am happy to say that I have just recently learned we are getting more and more information on the sub ject. I was told recently that 21 days is now the period for most vegetable crops and, even more recently, that some have even a smaller lapse of time between harvest and the last application. Moderator: Thank you Mr. Hayslip. l believe that later on in the panel there will be some further information de veloped on that one point. The next ques tions will be directed to Dr. E. G. Kel sheimer, Entomologist with the Vege table Crops Laboratory at Bradenton. Is Parathion compatible with fungicides and nutrients used in vegetable sprays? Dr. Kelsheimer: Parathion is com patible with our dithicarbamates and copper sprays commonly used on vege tables. There is one exception; you should not use lime in combination with the carbamate fungicides. It is com patible with practically all our insecti cides; again, one exception, which is cryolite. A common practice with us is to add nutrients to the combination of insecticidal and fungicidal sprays but we have evidence to show that an excess of zinc and iron, and naturally lime, has an adverse effect on Parathion. Moderator: What is the best time of day to apply Parathion on vegetables? Dr. Kelsheimer: We find that the best time to apply Parathion is the latter part of the day and especially after the dew is off the plants. We have found that Parathion will cause burn on toma toes and cucurbits, such as squash and cucumber, when the foliage is wet. Moderator: Thank you Dr. Kelshei mer. The next questions will be directed to Dr. J. W. Wilson, Entomologist at the Central Florida Experiment Station, Sanford. Does Parathion kill insects by fumiga tion or is it necessary for the Parathion to come in' contact with the insects to be effective? Dr. Wilson: Parathion is capable of killing insects by acting as a fumigant, a contact poison or as a stomach poison. Thus it is not necessary for Parathion to come into contact with the individual insects to kill them. But the greatest benefit from Parathion is obtained when it is applied to thoroughly cover the entire leaf surfaces and particularly the lower surface where most insects are found. Moderator: Why is Parathion so often recommended for use on vegetable crops in preference to nicotine sulfate?

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72 FLORIDA STATE HORTICULTUHAL SOCIETY, 1950 Dr. Wilson: That question, I think, refers to the weather conditions under which vegetable crops are grown in Flor ida. Nicotine sulfate requires tempera tures of 80 F. and should be applied when there is little or n . o air movement to be most effective. We seldom have weather conditions favorable for the most effective use of nicotine sulfate. Parathion is more effective than nicotine sulfate under our weather conditions. Moderator: What information is available on the residues which may be found on vegetables following the use of Parathion 'l Dr. Wilson: The residue data avail able for Parathion on Florida grown vegetables are rather meager but the in formation we have in conjunction with information from other sections of the country indicates that Parathion de teriorates rather rapidly. After from two to four days very little Parathion remains on the vegetable and after a period of twelve to fifteen days only traces of Parathion can be found. Moderator: Thank you Dr. Wilson. The next questions will be directed to Dr . . D. 0. Wolfenbarger, Entomologist at the Sub-Tropical Experiment Station, Homestead. Is Parathion satisfactory for control of soil inhabiting insects? Dr. Wolfenbarger: Mr. Thames of the Everglades Experiment Station is finding it is very satisfactory for use on the muck soils there for the control of wireworms. In Perrine marl soils of Dade county it is a little different story there, and Parathion has not been effec tive in wireworm control on our potato growing soils. Moderator: Are any precautions ad visable for use of Parathion on leafy crop plants? Dr. Wolfenbarger: Yes, that is one place where we need a great deal of pre caution. One of the places of questionable use of Parathion is on our leafy vegetables and on our fruits that we eat. Potatoes, on the other hand, is an ex ample of a crop where we don't need to worry about the residue problem. Moderator: How frequently need Parathion applications be made for pest control on vegetable crops? Dr. Wolfenbarger: The answer to that question, I am afraid, is very vari able and it will depend to the greatest extent on your insect infestations. If you have a very heavy one, you may have to put it on every five to seven days or so to combat that infestation. On the other hand, if your infestation is fairly light, or incipient, one or two applications may be satisfactory to control the pests in that case. Moderator: Thank you Dr. Wolfen barger. The next questions will be di rected to Dr. Herbert Spencer, Entomol ogist with the U. S. Department of Agri culture Sub-Tropical Fruit Insects Labo ratory at Fort Pierce. Dr. Spencer, these two questions deal with subtropical fruits. What pineapple pests have been con trolled with Parathion? Dr. Spencer: The pineapple mealy bug is the main one, and there is some evidence that the red spider of pineapple may be partially controlled with it. Moderator: How does Parathion com pare with DDT for control of little fire ants? Dr. Spencer: The little fire ants on subtropical fruits and on citrus can be controlled by the applications of Para thion used for scale control, for a period of about four months. DDT gives a longer period of protection. You get about eight months protection from DDT on the trunks of the trees, whereas you get about four months protection against the fire ants from th . e Parathion spray applied with complete coverage. Moderator: Thank you Dr. Spencer.

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THULLBERY: . PANEL ON PARATHION 7 3 Continuing with the subtropical fruits, Dr. Wolfenbarger. On what subtropical fruits may Para thion we used? For what pests? Dr. Wolfenbarg e r: It seems that Parathion has a very wide use on many of our subtropical plants, beginning with the avocado. It has been used on the avocado for dictospermum scale, in which case it seems it compares very favorably with oil emulsion for control of the scale and then, in addition, there is not the danger of plant injury. It gets the red banded thrips on avocados. It gets the leafrollers and is very effective for many places, it seems, for avocados. It has been used on limes, for example, in which case it is equivalent to oil and, in addi tion, there is not the chance for plant injury there. It has been used on mangos for lesser snow scale and other scales on mangos. It would seem to me that it would have a very widespread use on the mango for all of its scale pests, and for the red banded thrips . It is very effective in those cases. There is one precaution, when you use Parathion on mangos or avocados in the season when you can expect mite infestations, and that is you had better put in your sulfur with the Parathion to combat and control the mite and spider populations. If you don't, they will build up on the subtropi cals, as Mr. Thompson mentioned for citrus. Moderator: What dosages are recom mended for use on subtropical fruits? Dr. Wolfenbarger: About one pound, the same as is generally used for other plant pests. Moderator: The next questions will be on ornamentals and directed to Dr. L. C. Kuitert, Entomologist at the Agricul tural Experiment Station, Gainesville. What is the present status regarding the effectiveness of Parathion sprays in controlling insect infestations on orna mentals? Dr . Kititert: Parathion appears to be somewhat superior to oil emulsions. It has the advantage that it can be applied at seasons of the year when you can't apply oil emulsions. It will control a s effectively and, in some cases, more effec tively most of the insect pest s of our choice ornamentals. Moderator: In your opinion, can th e home gardener use Parathion safely? Dr. Kuitert: Yes, I feel they can if they follow a few simple precautions. I don't think that a mask will be necessary if they are very careful in mixing their insecticides. Most of the home garden ers would only apply the material to per haps six or eight ornamentals at a time. The short length of exposure and the in frequency of the application would, in my opinion, be safe for the home gardener. Moderator: Thank you Dr. Kuitert. The next questions are directed to Mr. R. P. Tomasello of the Wilson Spraying and Supply Co., Inc. at West Palm Beach, Florida. Has Parathion caused any spray injury to ornamentals? Mr. Toma se llo: Parathion has caused some injury to Hibiscus, Oleanders, Aralias and Bougainvilleas. There is a shedding of the older leaves when Para thion has been used at the rate of 1 % pounds of 15 % wettable Parathion to 100 gallons of water. This is especially noticeable when spraying has followed high winds or if plant s suffer from a lack of adequate moisture or food. Cer tain varieties of the above named orna mentals appear to be more susceptible to injury than others. Moderator: Has any illness been re ported by home owners following the use of Parathion on foundation plantings, etc? Mr. Tomasello: Because we are aware of the potential dangers of Parathion, a careful check has been made of the homes where this material has been used. We

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74 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 have been using Parathion approximately two years and during this time there has not been a single report by home-owners of illness following its use on foundation plantings. Moderator: That completes Part I of our questions. We will now proceed to Part II, dealing with practical considera tions for growers in field use. The next questions will be directed to Mr. Wilbur Charles, Production Manager of the Florence Citrus Growers Association of Florence Villa. What precautions should . be used to protect the user of Parathion from danger? M1'. Charl e s: We have equipped our men with coveralls and masks . We have not adopted the use of rubber gloves. Mod e rator: How do the growers liv ing in groves feel about using Parathion near their homes? Mr. Charles: We have several grow ers of the association living in their groves . When we started using Para thion each of these were consulted as to whether we were to use this material around their houses or not. In each case, the grower consented, in fact, he now asks us to use it around the house the same as any other insecticide. Moderator: What changes in the groves have been observed, if any, from the use of Parathion as compared to oil? Mr. Charles: The outstanding effect that I think I see from the use of Para thion is in the older groves, such as we have in this section. The older groves that have been here since the early 1900s, I feel, were beginning to show a great toxicity to the use of oils. Since we have been using the Parathion, I see a great improvement in the condition of the groves. This I know is not due to any change in fertilizer because the fer tilizer program has been the same. We, of course, have had dry weather to combat but, even with that, the groves are in better physical condition. Moderator: Thank you Mr. Charles. We will next hear from Mr. Willard D. Miller, chairman of the research com mittee of the Florida Fruit and Vegetable Association at Ruskin, Florida. What effect has sunshine and rain on removing any objectionable residue from Parathion? Mr. Miller: That is a question, Mr. Moderator, that I have asked someone else to answer for me. I want to hear from somebody who is qualified to an swer it. Moderator: We will be glad to direct it to some other member of the panel. Mr. Mill e r: If you please. Moderator: Alright. The next ques tion here may also fall into that category. You be frank and say so if it does. How close to picking time can Para thion be used on the following vegetables without danger of having excess residue which may be questioned by the Pure Food and Drug Administration? Now there are four or five vegetable crops listed. The moderator would be inclined to guess you would want that question to lay over to Dr. Gleissner who is going to discuss the answer to questions on the status of Food and Drug hearing. Mr. Miller: Yes, you asked me to be frank; that was another one that I wanted somebody else to answer for me. Moderator: Thank you Mr. Miller. Now, while we are on this subject, I want to ask Dr. Gleissner a question on this very interesting subject. Have the manufacturers of Parathion recommended any certain amount of residue that they feel can remain ori a vegetable without injury to the con sumer? Dr. Gleissner: Yes sir. Both the manufacturers of Parathion and repre sentatives of the Food and Drug Admin istration presented data at the Food and

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THULLBERY: PANEL ON PARATHION 75 Drug Administration hearings to the effect that a residual level somewhere between two and five parts per million would not be hazardous to consumers. The American Cyanamid Company placed data in the record which indicated that even a considerably greater residual tolerance could be allowed and still be conservative but under the conditions of the uses of Parathion, two to five parts is the largest that will ever be necessary. Moderat01: Thank you. I wonder if I might ask another one of these ques tions to Dr. Kelsheimer or Dr. Wolfen barger. What effect has sunshine and rain on removing any objectionable residue of Parathion? Dr. Kelsheimer: What meager records we have show that Parathion is broken down very quickly under our sunlight conditions. Do you want the rainfall? Moderator: Yes. Dr. Kelsheimer: The rainfall also tends to wash off this residue. Moderator: Thank you. I see there is another question, Dr. Kelsheimer, which has been answered in part. The question is as follows: How close to picking time can Para thion be used on the following vegetables without danger of having excess residue which may be questioned by the Pure Food and Drug Administration? The commodities are tomatoes, cucumbers, peppers and leaf crops such as cabbage and lettuce. Do you think that has been answered or do you care to comment? Dr. Kelsheimer: I believe that has been answered. Moderator: Thank you. The next questions will be directed to Mr. J. J. Taylor of the State Department of Agri culture from Tallahassee, Florida, on State Label, Package and Control data. Are there adequate methods for deter mining Parathion? Mr. Taylor: Yes. There ~re Fl num• ber of methods for determining Para thion. The method we use in our labora tory is the colorimetric method, which was developed by Averill and Morris for residues of Parathion modified to use for dust formulations. There are a num ber of other methods in use but we have found this to be the most satisfactory and that is the one we use for regulatory purposes. Moderator: Have you found accurate methods for both concentrate and dilute mixtures? Mr. Taylor: Yes. The method is ac curate both for concentrate and dilute mixtures. It is, of course, more accurate in the smaller amounts; possibly ac curate in the 15 and 25 percent concen trates to something like a one-half or one quarter of 1 %. Moderator: Do you find that Para thion mixtures usually come up to their guarantee? Mr. Taylor: For the most part Parathion mixtures meet their guaran tees. A few have failed to do so. We found most of the companies put up their 15 and 25 percent concentrate in tin con tainers. For 1 percent dust, some com panies use paper bags with inner lin ings; some, containers with tin top and bottom and cardboard sides. These seem very satisfactory but even some of the paper bags with inner linings don't seem to hold the dust in too well. Moderator: Thank you Mr. Taylor. We will now have Section III, Citrus Fruit Quality Factors. The questions are directed to Dr. Paul L. Harding, Fruit and Vegetable Handling, Trans portation and Storage Investigations, U. S. Department of Agriculture, Orlan do, Florida. Is Parathion spray superior to oil in increasing the total solids content wheth er applied in either June or August, or at both times? Dr. !I ardinr,: A few, ;velr& ago the

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76 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Bureau of Entomology and Plant Quar antine and the Bureau of Plant Industry, both of the U. S. Department of Agricul ture, set up experiments to determine the effect of oil and Parathion sprays on the composition of oranges. During the first two years the work was on Valencia oranges. Emphasis during the last two years has been on early oranges with the tests being made on the varieties Parson Brown and Hamlin. The results of these studies show: A. That Parathion is defi nately superior to oil in increasing the total solids content whether applied in June or August or at both times. B. That oil applied in June does not seem to have a depressing effect on total solids con tent. C. That oil applied in August has a very depressing effect on total solids. Moderator: Did your studies show that Parathion increased the total solids content over the controls? Dr. Harding: The question is asked, "Did Parathion definitely stimulate or give a definite increase in total solids over the control?" When we compare Parathion applied in June and August with the controls we find that there is a difference of .23 which tells us there is a significant difference between the con trol and Parathion applied in June and August. We can similarly establish the fact that oil sprays depress the total solids level by comparing the treatment of oil applied in August, or the treat ment of oil applied in June and August, with the control. To summarize our findings, our results show that single applications of Parathion applied in June or in August did not significantly affect the total solids content when compared with the controls. On the other hand, two applications of Parathion, one ap plied in June and the other in August, did significantly increase total solids. Moderator: What is the general ef fect of oil and Parathion sprays on Vitamin C, total acid, and the degreening of fruit? Dr. Harding: The ascorbic acid (Vita min C), and the total acid content of the fruit was slightly depressed by the ap plication of oil sprays. The differences were small and the decrease generally re sulted from the applications of oil in August. Parathion sprays had very little effect on Vitamin C and the results indicate a very slight increase when our data are compared with the control fruit. The results are of interest from a scien tific point of view but it should be pointed out that the increase is too small to be of practical value. The effect that various sprays have on the degreening of fruit or on the color of the rind is of im portance to the citrus grower and ship per. It was, therefore, of considerable interest to find that the fruit which we sprayed with Parathion should degreen at an earlier date than the fruit from either the oil or controlled plots. The brighter color of the fruit from the Parathion plots appeared to persist into the stage of over-ripeness, however the differences among treatments are not so marked when the fruit is completely degreened. Our results show that the late oil sprays applied in August are largely responsible for the depressive effect in total solids, total acid and Vita min C, as well as the failure of the fruit to degreen as early as when sprayed with Parathion. I wish to emphasize that the early (June) applications of oil had very little deleterious effect on fruit composi tion or on the rind color of the fruit. Moderator: Thank you Dr. Harding. Dr. J. W. Sites, Horticulturist with the Citrus Experiment Station, Lake Alfred, Florida, the next set of questions will be directed to you. Have appreciable differences in the soluble solids content of the juice of fruit from trees, spr.ayed with Parathion as

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THULLBERY: PANEL ON PARATHION 77 contrasted to trees sprayed with oil at the same time, been found? Dr. Sites: Yes. Very appreciable differences have been found. Of course, the magnitude of these differences de pends on the time of the application of the oil spray. Where we checked groves throughout the state last year, for ex ample, the differences, where we were comparing Parathion sprays to oil sprays applied about the middle of June varied between three-tenths Brix unit and one Brix unit. Moderator: Does the rate of appli cation of Parathion affect the soluble solids content of the fruit? Dr. Sites: The work which we have done thus far indicates that the rate of application has practically no effect on the soluble solids content of citrus. Moderator: Is the use of Parathion in place of oil sprays for scale control equally effective for all varieties in so far as the quality of the fruit produced is concerned? Dr. Sites: So long as one is compar ing Parathion against oil sprays it would have to be stated that you cannot expect the same effect for the use of Parathion for all varieties. The reason for this is not that the Parathion is less effective on certain varieties, but rather that oil sprays do not cause the same effect con sistently for all varieties. Because oil sprays usually do not cause as severe lowering of the soluble solids content in grapefruit as in oranges, it follows that one could not expect as much increase in the soluble solids content of grapefruit varieties where Parathion was used in place of oil sprays. Moderator: Is there any reason to be lieve that the use of Parathion sprays will result in the production of fruit with a higher soluble solids content than would have been produced had no sprays for scale control been applied? l)r, Sites; That question goes back to the fact it was more or less intimated early in the use of Parathion that bene fits were . being gained by its use over and above the limitations set by the generic pattern of the tree itself. I do not believe that is true. Moderator: Thank you Dr. Sites. Part IV is Proc e ssed Citrus Products Factors. The field of Molasses and Feed will be addressed to Mr. R. N. Hendrick son, Assistant Chemist at the Citrus Ex periment Station, Lake Alfred, Florida. Has Parathion been found in citrus pulp or citrus molasses and, if so, in what quantity? Mr. Hendrickson: Citrus pulp and molasses made from grapefruit peel sprayed with 25/100 pounds active Parathion per 100 gallons was found to have approximately one part per million in the dried feed and one-half parts per million in the molasses. The Parathion content of the wet peel in this instance was considered to be an average value. Moderator: Is the quantity of Para tion present in feed and molasses harm ful to dairy or beef cattle? Mr. Hendrickson: Feeding trials at the Kansas Agricultural Experiment Station where dairy cattle were fed five parts per million on a total feed basis for 81 days and thereafter slowly in creased to 40 parts per million, showed the Parathion as having no harmful effect on the health of the cow. No Parathion was found in the milk, nor any objectionable off flavors. Coopera tive studies between the University of Illinois, a large packing company and the American Cyanamid Company, in which beef animals consumed five parts per million actual Parathion, based on the silage intake of their diet for 100 days finishing period, showed no Para thion in the fat, lean meat, or liver tissue at the time of slaughter. Moderator: Thank yon Mr. Hendrick son. The next questions on peel oil will

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78 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 be addressed to Mr. J. W. Kesterson, As sociate Chemist at the Citrus Experiment Station, Lake Alfred, Florida. Where is Parathion found in the citrus fruit and in what concentrations? Mr. Kesterson: The oil cells are the only part of the fruit in which the Para thion is retained. In 23 samples of cold pressed oil studied this year, for both orange and grapefruit the concentration of Parathion was found to range from 0 to 236 parts per million. In 75 percent of the samples, the range was O to 60 parts per million. Moderator: Does the presence of Parathion in a coldpressed citrus oil harm the oil? Mr. Kesterson: No. The presence of Parathion did not show any noticeable influence on the physical or chemical characteristics of the oil. Warburg respirometer studies to determine the keeping quality . or oxidative stability of the oil showed , Parathion , to have .the beneficial effect of slightly increasing the stability of the oil. Moderator: Thank you Mr. Kester son. The next questions relate to Residues in Citrus Products and will be addressed to Mr. C. R. Stearns, Jr., As sociate Chemist at the Citrus Experiment Station, Lake Alfred, Florida. Does the Parathion penetrate through the peel and contaminate the juice por tion of the fruit? Mr. Stearns: No. In reemphasizing Mr. Kesterson's statement, the Parathion does not penetrate through the peel of the fruit. Moderator: If Parathion is present in the peel, will the juice expressed by different commercial extractors be con taminated with Parathion? Mr. Stearns: In some cases we have found very small amounts of Parathion; however, these values present no health hazard and therefore are of no conse quence. Moderator: Thank you Mr. Stearns. The next questions, related to Canned Citrus Products, are addressed to Mr. R . W. Olsen, Biochemist at the Citrus Ex periment Station, Lake Alfred, Florida. Does Parathion sprayed on groves have any effect on flavor or keeping quality of canned citrus? Mr. Olsen: We found no difference in flavor between the Parathion sprayed fruit and the control in freshly extracted juice or, upon storage, of the finished product. Moderator: What happens to the Parathion, if any is present, during pro cessing? Mr. Olsen: Orange juice containing Parathion lost up to 48 percent of the Parathion during the processing of single strength orange juice and up to about 25 percent in the manufacture of frozen concentrate. Moderator: Thank you, Mr. Olsen. . Part Von the program relates to Human Health Aspects with Reference to Fac tory and Field Workers: Safety Precau tions; Preventive Measures: Practical and Professional Steps that have Been Developed and Are Important to Em ployer and Employees; Residues; Air Contamination; Public Health and In dustrial Commission Considerations. The first questions will be directed to Dr. John W. Williams, Pathologist at Mor rell Memorial Hospital, Lakeland, Flor ida, relating to indications of suscepti bility, coupled with symptoms and treat ment. Should individuals about to work with Parathion be given medical examination? If so, why? And are there any specific examinations indicated? Dr. Williams: The answer is yes. In dividuals about to work with Parathion should be given medical examinations. It is important to determine whether the individual is a psychoneurotic or not. If the grower employs a psychoneurotic, _ he

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THULLBERY : PANEL ON PARATHION 7fJ can expect headaches. Certain laboratory examinations should be done. These laboratory examinations can all be done on one specimen of blood taken from the vein. They are hemoglobin for anemia. An individual about to work with Para thion should have a hemoglobin above 75%. Second, there should be an ex amination for blood proteins. The total protein should be above 6%. The third examination is for cholinesterase. The cholinesterase should be 75% or more. Now what are the implications of low values in the above examinations? Low hemoglobin indicates fewer blood cells to contain cholinesterase, and low blood proteins indicate possible liver damage which organ is the site of production of cholinesterase. Low cholinesterase indi cates less of this protective substance to destroy acetylcholine which, if in excess, produces the signs and symptoms of the poisoning. Moderator: Should an individual working with Parathion be checked oc casionally? If so, are there any signs and symptoms which should be looked for? Dr. Williams: This is advisable until there is more detailed knowledge of this problem. If the worker shows a marked reduction of cholinesterase, it is ad visable to withdraw him from exposure. A reduction of 20% to 65% or lower even without symptoms, should be con sidered reason for withdrawal. Muscle twitchings, digestive symptoms such as abdominal cramps, nausea, vomiting, or change in vision, or nervous symptoms such as headaches, feeling of dullness, dizziness should be looked for and in vestigated. Moderator: Are some persons more sensitive to Parathion than others? Dr. Williams: Yes. Less Parathion would be necessary to cause ill effects in persons with anemia or liver damage. Those who have been exposed with reduction of cholinesterase would be more . sensitive. It is probable, also, that some may store Parathion in the lipoid layers of the skin from which it may be ab sorbed from time to time, producing symptoms or delaying recovery. It is possible that some have noticed discrepancies in reports of cholinesterase from various laboratories. I believe that mistakes have been made by laboratories where there has been lack of experience on the part of the technician with the potentiometer. It takes considerable ex perience to handle this instrument prop erly. When I worked in close coopera tion with those developing this instru ment, we found some very excellent laboratories storing it in attics or the like because they did not have the pati ence to study its pecularities and master its use. Moderator: When would a person who has experienced symptoms from Parathion be allowed to resume work with this substance? Dr. Williams: The usual tiP1e given is 60 days. In order for the plasma cholinesterase to reach normal it takes about three weeks, and for the red cell, about three months. The plasma cholinesterase should be normal, and that of the red cells at least 75% of normal, and because of the experience, the work er should be watched closely. Moderator: Thank you Dr. Williams. The next set of questions is in relation to Safety Precautions in Industrial Plant s and is directed to Dr. John M. McDonald, Director of the Division of Industrial Hygiene, Florida State Board of Health, Jacksonville, Florida. What mechanical installations are necessary to provide a safe working at mosphere for employees engaged in blending Parathion? Dr. McDonald: Thank you Mr . Chair man. As most of you know, no doubt, Parathion comes to our mixing and blend

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80 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 ing plants in strengths of, well, maybe the technical grade, of liquid Parathion or 15 percent or 25 percent powder. The job in the processing plant is to dilute that raw material down to the strength that is used in the field, perhaps three, two, one or down even to one-half per cent. The other job they have to do is to pack that diluted material for distribu tion. In all this work, the essential thing is to keep Parathion dust and Parathion vapor out of the air of the factory, and that is usually accomplished by what is known as a closed system. The materials are first of all dumped at a dumping sta tion which is protected by exhaust venti lation; i.e., air is drawn in at that station to pick up any dust or vapors that may get loose in the process of opening pack ages. Then, the material is carried in an airtight duct to the grinders, and then to the mixers or blenders. All of these machines are tightly enclosed. From there it goes to a hopper, usually fairly well up in the factory, and from the hop per it drops into the bagging system. The bagging machine is in a small chamber and it also has exhaust ventilation to pull out any dust or vapors that may escape as the material comes down from the hopper. The exhausted air that comes from these various stations I have men tioned, is then led to a bag filter and, after that, it goes to a scrubber, that is, a system of sprays (water sprays) in an enclosed cylinder, before it is discharged to the open air. One other point is, I think, worth mentioning here; that if any of the material is spilled on the floor in the factory, it should be neutralized with a strong alkali solution. Moderator: What personal protection should be provided for the employees to work at this job? Dr. McDonald: For the employees themselves in addition to the machines I have mentioned, first of all, a hat; over alls or coveralls which fit tightly around the neck; rubber gloves; rubber shoes; if there is any splashing of liquid Parathion then, of course, a rubber apron or per haps a rubber suit; in addition to that a respirator or, as it is sometimes called, a mask.. He should, of course, have plenty of showers, soap and hot water, where he can wash himself at the end of the day. He should also wash himself before he eats or smokes, as someone has men tioned previously here. I think it is a good idea to have a separate lunchroom and clean place where he can go and eat his lunch. One other small point-I would be very wary of overtime in a Parathion packing plant. Moderator: What is the one most important consideration in the preven tion of Parathion poisoning? Dr. McDonald: The one most im portant consideration is good supervision. Machines break down, connections break loose, and we must have somebody who knows how to repair those things and keep the machines in order. Also, the people who work in the plants are human beings just like you and me; they make mistakes, get a little careless and tend sometimes to think these precautions that we are preaching so vehemently are not quite as necessary as we make out. I have had experience in lead factories and I know that supervision is one of the most difficult things to effect. Perhaps the best idea there is to have the super visor or foreman obey all the rules, even to the tiniest one. Wear his respira.tci'r, change his clothing and do as we have been prescribing here for the employees in the factory. Moderator: Thank you Dr. McDonald. The next questions are on Precautions in Handling in the Field, directed to Dr. J. T. Griffiths, Associate Entomologist from the Citrus Experiment Station, Lake Alfred, Florida. In what type of job is a man most likely to be affected?

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THULLBERY: PANEL ON PARATHION 81 Dr. Griffiths: Iri a survey of the cases of parathion poisoning which oc curred during citrus spray operations, it was found that the most cases were en countered among men spraying with hand guns. Very few Speed Sprayer operators were sick, but men filling sup ply units were sick in a number of cases. Moderator: What danger is there in entering or working in a grove after it has been sprayed with Parathion? Dr. Griffiths: There is some danger for anyone entering a grove after it has been sprayed with Parathion because of the intimate contact with foliage and fruit that has Parathion residue on it, and because of the possible contamination from vapors. In one experiment this past summer here in Florida, we had animals exposed in a grove immediately following the application of excessive amounts of Parathion. Some of these animals were exposed for as long . as 10 days. During that time, blood was checked for changes in the amount of cholinesterase present and the animals were checked at autopsy. No adverse effects attributable to Parathion were found. Those that were left in the grove were perfectly healthy at the end of the 10 days. Thus, the major precaution for anyone going into a grove after it has been sprayed, is to avoid contamina tion with the foliage and with the fruit. In other words, any job which is going to take an individual into intimate con tact with the.tree itself should be avoided for some period after the time of spray ing. We are suggesting now that for such things as irrigation, cultivation, a matter of seven days following applica tion will be a safe period for grove labor. Moderator: Do you know if there have been any illnesses or deaths in Flor ida during 1950? Dr. Griffiths: There have been a number of illnesses. There have been no deaths. So far as I know personally, to date there have been no deaths in the United States in the field attributable to Parathion. Certainly, there have been none in Florida. We have had some 50 cases that we have actually checked on at the Experiment Station. These repre sent, maybe, 50 percent of the total cases in the state. A high percentage were very questionable; about 25 percent were definitely not Parathion poisoning. Moderator: Continuing with Precau tions in Handling in the Field, maybe we had better address this jointly to Drs. Griffiths and Gleissner. Will you list, in approximate order of importance, the protective devices and protective handling procedures to avoid Parathion poisoning? Bear in mind this ha& to do with "in the field." Dr. Griffiths: This will be based on our experience here in Florida, particu larly this year . I think the thing we failed to emphasize sufficiently for most people was the danger of skin absorption. By and large, the men have worn respi rators. Some outfits have been faithful about changing clothes and taking daily baths. Skin absorption begins to look like the way in which many men are be coming contaminated. They have not been careful enough; they have been wearing short sleeves; they haven't worn rubber gloves; and they haven't been careful about taking a bath at the end of the day. The primary thing is to avoid exposure to the Parathion itself; In other words, don't get it on you; don't breathe it. Anything that you can do to prevent contamination is the thing to be done. This means changing clothes daily, wear ing a respirator, wearing a hat, and above all be careful. Moderator: Thank you Dr. Griffiths . Dr. Gleissner, would you care to com ment on that? Dr. Gle i ssner: Dr. Griffiths very well pointed out the important considerations for citrus. As you understand, Para

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82 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 thion was used both as a dust and as a spray. As a dust, it presents a respira tory hazard; and we continue to empha size the respirator under those circum stances. I also would like to point out that protective devices and protective handling features really complement and supplement each other. That is, one is a check on the other. In other words, you know individuals who have been able to handle Parathion without many of the protective devices and they get away with it. Still, I want to emphasize it is good supplementary procedure to have both followed to the letter. Moderator: Thank you. The next questions will deal with Residues, Post Application Phases, directed to Mr. C. R. Stearns, Jr., who has answered some other questions earlier. How rapidly does Parathion disappear from the leaf and fruit surfaces? Mr. Stearns: Usually at the end of one week's time 90 percent of the Para thion has disappeared from the surface of the foliage and fruit. Moderator: If Parathion volatilizes so rapidly is it dangerous to stay in groves for long periods of time immedi ately following the application of Para thion? Mr. Stearns: As Dr. Griffiths pointed out, if no contact with foliage, limbs or fruit is made, there is no danger from vapor concentrations that may be present in the air. Moderator: On the basis of our present information, Mr. Stearns, what can be said concerning the time for safe entry into groves and fields following treatment with Parathion? Mr. Stearns: Again, as Dr. Griffiths pointed out, we are considering seven days for cultivation, irrigation or any other operation where no contact is made with the foliage, limbs or fruit. With regard to pruning and fruit picking, we are still adhering to the recommendations that were made last year, that is 30 days following the application of Parathion to the grove. Moderator: Thank you Mr. Stearns. The next question will deal with Public Health, and directed to Mr. John Mulren nan, Director of the Division of Ento mology, State Board of Health, Jackson ville, Florida. Question is as follows: What steps have been taken by the State Board of Health to inform the medical profession and public health workers regarding the toxic properties of Parathion? Mr. Mulrennan: That question can better be answered by a demonstration. We have sent out to the medical profes sion in Florida a blotter which called the attention of the doctor to the symptoms and treatment of Parathion. A second blotter presented a second warning on Parathion which gave the symptoms and treatment and also suggested never to use morphine. A leaflet on Parathion in some detail was also presented to the medical profession. A reprint was secured from the New York State Journal of Medicine, Volume 50, No. 13, July 1, 1950, entitled "Physicians and Phosphate Insecticides," which was presented to the medical profession. All pharmacists in the state of Florida have received two notices pertaining to the symptoms of Parathion. All hospitals in the state of Florida were sent a placard to hang in their emergency room pertaining to Parathion, its symptoms in man and the treatment for same. All county health departments received a mimeographed brochure pertaining to Parathion in addition to all the informa tion that had been sent to the doctors, pharmacists and hospitals. A state-wide news release pertaining to Parathion was released to the press on March 10, 1950. Moderator: Thank you Mr. Mulren

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THULLBERY: PANEL ON PARATHION 83 nan. Considerations of the Florida In dustrial Commission will be given by Mr. Wendell Heaton, General Counsel for the Florida State Industrial Commission, Tallahassee, Florida. What interest does the Commission have in this subject? Mr. Heaton: The Commission, other than the general interest of everyone, is interested in the use of Parathion from the standpoint of its administration of the Workmen's Compensation Act. We think the use of this insecticide should be surrounded with caution and that men and supervisors should be carefully trained. We are convinced that it can be used safely a_nd we know that it means much to the industry. Moderator: Would the Commission encourage pre-employment examina tions? Mr. H e aton: The Commission ap proaches this subject with some misgiv ing, but in this instance that, no doubt, is the only way that high susceptability may be determined. These pre-employ ment examinations should be made only for the purpose of discovering suscepti bility to this chemical and not let such an examination prevent employment be cause of other physical handicaps. I don't know whether we would permit Dr. Wil liams to rule out all psychoneurotics; I don't know how limited that would make our labor in this industry. Moderator: Thank you Mr. Heaton. Will the Commission cooperate in re quiring necessary precautions in the use of Parathion? Mr. Heaton: The Commission will not only cooperate in that field but are very anxious to do so. In trying to be of some assistance to the industries, the Commission has, during the past year, entered into some very extensive studies with reference to illnesses and accidents traceable either directly or indirectly to Parathion. These studies are most interesting. It might be well to mention just briefly that the reported accidents range in importance from these causes: first and foremost and, I believe Dr . Grif fiths will agree with me here, the acci dents 1eported have been caused from improper use of masks or respirators, or a lack of the use of them; second in im portance is improper clothing being worn; and third, improper bathing facili ties being provided. Of course, an over all cause is, as we all know, lack of proper supervision of the employees in their use of Parathion. Moderator: Thank you Mr. Heaton. The next question has to do with the Status of U.S. Food and Drug Hearings with R e f e rence to Use of Parathion. What is the status of these Food and Drug hearings with reference to the use of Parathion? Dr. Gleissner would you give us that? Dr. Gleissner: The present status of Parathion, as with all our newer organic insecticides, is that we do not have any thing official from the Food and Drug Administration at this time. However, since January 17, this year a very de tailed hearing has been conducted. Inci dent to that, I want to tell you that growers here in Florida should be ex tremely proud of the fine presentation by your Florida representatives-one of the two best of any state representatives at the hearing. We obviously cannot say anything more than that the record is complete. I have already mentioned to you what their contention is on Para thion-i.e., that two to five parts per million would not be considered a con sumer health hazard. Also, in published papers, representatives of the Food and Drug Administration have confirmed that same tolerance level. Now, it is extremely important from the standpoint of the timing of the last application and harvest, that we do know what kind of a level we have to shoot at. It is rumored

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84 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 that we will not get anything official until sometime in June. Now that is, in my opinion, entirely too late for most of the growers in the United States to plan a program in an orderly manner, and it is hoped that something official can be given this winter. I might say on that score, a very adequate presentation is available on Parathion as well as many other organic insecticides, and I think we can look forward optimistically to a good intelligent conclusion to be drawn from this information. Moderator: Thank you Dr. Gleissner. In the next set of questions there are one or two which, in an indirect way, concern use of Parathion. It has to do with the birds and bees. I would like to direct some to Mr. Stearns, some to Dr. Griffiths and some to Dr. Gleissner. Have there been any scientific studies made to get facts on potential impact of Parathion use, in groves or farms, on wildlife and bees? Mr. Stearns will comment first on bees. Mr. Stearns: First, I would like to find out if Mr. Robinson, entomologist from the main station is present. I would like to have him give that report as he cooperated with us at the experiment station this summer on our spray trials. Mr. Robinson's conclusions as to the effects of Parathion spray on bees were that there would be higher mortalities if the bees came directly in contact with the spray. The bees were placed in this grove we were carrying on the experi ment in, prior to the spraying, and were present during the spraying. Now, we must remember that the trees were not in bloom so we cannot tell what would happen had the trees been in bloom and the bees out working. However, there was some mortality of the bees that were in the grove during the spray operation. Part of that mortality was due to the moving of the bees from one place to an other. With regard to the post application sprays, Mr. Robinson did not feel that there were any disastrous results, as, in that case also, some bees were killed or died and he felt that also was due to the moving of the bees. We can not tell you what the effect would have been had the trees been in bloom and the bees out working. Moderator: Thank you Mr. Stearns. Dr. Griffiths, do you care to comment on this same thing? Has there been any work at the Experiment Station done on pigeons or other birds? Dr. Griffiths: In this grove that Mr. Stearns was talking about, we exposed rabbits, rats, pigeons and chickens. There has been some comment locally that birds were being killed in groves. Pigeons and chickens certainly come in the category of being birds. We had no ill effects whatsoever in this grove sprayed with more Parathion than would normally be sprayed in any grove in Florida. I would like to hazard a guess concerning the effect on bees if Parathion is used at post-bloom time. Post-bloom time means that all the petals are on the ground and, presumably, it's from one or two days to maybe as much as three weeks following petal fall. There will be no bees in the grove at that time feeding on blossoms. During the time that blossoms and bees are both present, no spraying of Para thion will occur so there should be very little, if any, complication at that season of the year. We have heard some rumors of complaints but we haven't been ac tually able to trace down those rumors as being authentic or as having any real basis in fact. Moderator: Dr . Gleissner, would you have any direct information or know of authentic reports on studies made on quail? Dr. Gleissner: Mr. Holland, I told you yesterday that I had in my briefcase several reports on quail, but I find that they concern pheasants in both cases.

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THULLBERY: PANEL ON PARATHION 85 For those who would like pheasants, I can give this. In Washington state this subject came up from the wildlife inter ests. They have a lot of pheasants out there that frequent orchards at certain times of the year. Pheasants were con fined in cages right under apple trees and the standard spray programs were ap plied, as well as experimental programs using very high dosages of Parathion. The pheasants were in the orchard at the time of spraying and were kept there for some period of time after spraying. At no time did the pheasants show any effect whatsoever. Now, in another case in California, it so happens that one of the wildlife interests came up with the rumor that pheasants had died by the hundreds in bean fields treated wth Parathion in connection with bean pest control. It was rumored that there were hundreds of dead pheasants in the bean fields after harvest. A state wildlife group set up an experiment in which they counted the pheasant population in these bean fields before treatment with Parathion; the regular treatment which was supposed to have caused the mortality was given; and a recount made after treatment. In no case did they find any dead pheasants attributable to Parathion. Moderator: While we are on the sub ject, do you have any information on fish? Very briefly, please. Dr. Gleissner: We have only very sketchy information. The information we have was gathered when someone was interested in using Parathion for a mos quito larvae control. They have found there that the dose to kill fish is consid erably higher than that necessary to kill mosquitoes. Now it is true that some small species of fish may be killed by a very careless dumping of Parathion dur ing the filling of the spray tank or some such situation like that. We do not con sider that Parathion will cause any un usual problems at all. Moderator: Thank you. Now we will get down very rapidly to some questions that came in late and should be bracketed in the final setup. This question is ad dressed to Mr. Thompson. Are red scale or black scale increasing as a result of using Parathion? Mr. Thompson: We have found that neither red nor black scale are increasing any more following Parathion than oil sprays. In fact some of the heaviest black scale infestations were in groves that had never been sprayed with Para tion. However, it has been found that parathion has not been quite so effective as an oil emulsion unless there is a high percentage of black scale in the young stages when the Parathion applications are made, in such cases Parathion was comparable with oil. Moderator: Thank you Mr. Thomp son. The next question, in the field of vegetables, I will address to Dr. Kel sheimer. Can Parathion be used upon such crops as cucumbers and tomatoes during the harvest season? Dr. Kelsheimer: In a bulletin we published it is recommended that Para thion be used on cucumbers and squash to the time of blooming and fruit set. On tomatoes we have a little different situation. Where Parathion is necessary we try to estimate within a week of the first harvest to make the application; then the fruit is harvested. At the time the fruit is harvested, if necessary to go in again, we do so immediately, but each time we wait a week before the fruit is picked. Our tomatoes are picked mature green and in the process of prepar~ng for market they are either washed, brushed or rubbed. What little residue is left on by that time will be, in our opinion, negligible. The very meager information that we have shows there may be a considerable amount of residue on the foliage but very little on the fruit.

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86 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 When it goes through this process for marketing, that is very little indeed. Moderator: Thank you. The next questions are still in the role of vege tables-on sweet corn-and addressed to Dr. Gleissner. Can sweet corn treated with Parathion be safely fed to livestock? Dr. Gleissner: Yes. Studies, both with dairy cows and beef animals, show that even when such feeds as alfalfa or corn silage are contaminated with Para thion at levels from ten to fifty times higher than would be present from the field use of Parathion sprays or dusts no Parathion came through in the milk, no Parathion was stored in body tissues, and there was no adverse effect on the health of the animals. Moderator: What are the hazards to people harvesting sweet corn which has been treated with Parathion up to ten days before harvest? Dr. Gleissner: The practical experi ences in the. Wisconsin sweet corn can ning area this past season, as well as re searches by industrial hygienists of American Cyanamid Company in coop eration with several state agencies, show that there should be no picker hazards if harvesting is delayed four days after the last application. The time might even be shortened after we have been able to conduct more studies but this timing is a reasonable one. It should be pointed out, however, that the present label claims state no applications within twelve days of harvest. Moderator: The next question is to Dr. Kelsheimer. A.t what poundage per day and over how many days in a row are vegetable growers exposed to Parathion? Dr. Kelsheimer: The application of Parathion by dust or by spray is over such a short period of time as compared with the citrus grower. It would be unusual for the vegetable grower to spray or dust with Parathion more than two days in succession. The vegetable grow er is in the open and is not concerned with a heavy canopy of foliage. Appli cations are made no oftener than once a week or every ten days and at such low rates as one pound of 15 percent wettable to 100 gallons of water. Dusts are either one or one and a half percent applied at the rate of thirty pou . nds per acre by ground machines or forty pounds by air plane. I don't have any figures on the poundage of material used in any one day by any of the growers. Moderator: Thank you Dr. Kelshei mer. There are only three more ques tions. They are in the field of citrus. This question we would like to direct to Mr. Thompson. How long does Parathion have to be on the trees for good scale control before a rain? Mr. Thompson and Dr. Spencer both can answer. Mr. Thompson: We do not have very much information about the kill of scale where a rain follows a Parathion applica tion. In one test a 95 percent kill was obtained where Parathion was applied at 9 o'clock and of one inch of rain fell between 3 and 4 o'clock. We have no in formation where there was rainfall one to six hours after the application. Moderator: Thank you. Dr. Spencer do you have anything to add to that? Dr. Spencer: l believe that if the spray dries on the foliage it will be effec tive, and you needn't worry about mod erate rains. Moderator: Thank you. Here is an other question; What effect will five pounds of 40 per cent Parathion have in slightly windy weather on scale control? Does a mem ber of the panel want to answer that? No answer. This next question will be addressed jointly to Mr. Kesterson and Dr. Sites. Does a spray containing petroleum oil

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THULLBERY: PANEL ON PARATHION 87 at less than the lethal dosage for scale, as perhaps or percent, fortified by Parathion, hold promise of being better than oil or Parathion alone in respect to (a) less red spider followup than Para thion alone, (b) less affected by rain fol lowing shortly after application than Parathion, (c) less harmful than oil to solids and coloring? May I ask Dr. Sites if he would care to comment on that last phase of the question? Dr. Sites: Based on the results of previous preliminary experiments, wher ever lower concentrations of oil have been used in oil sprays the lowering of the soluble solids content of the juice was less severe. I would expect therefor that reducing the concentration of oil to or percent would not cause as much re duction in the soluble solids content of the. juice as would have been the case had 1.3 percent oil been used. Moderator: Dr. Harding, would you care to comment on that question? No answer. Well, Mr. Kesterson, will you please answer the other parts of that question? Mr. Kesterson: I am not going to give a direct answer to the question but present some data which , may give an indirect answer. In our work on peel oil it was noted that when oil emulsions were combined with Parathion spray mixtures, the amount of Parathion sub sequently found in the peel oil was ap proximately twice the amount which would be expected to result from the use of Parathion alone. Parathion when combined with oil emulsion sprays is apparently an entirely different situation from that when Parathion is used alone, and possibly should be approached with caution until more information is ob tained for the combined use of these two spray materials. Moderator: Thank you. I wonder if there is any entomologist on the panel who would like to comment on phase (a) of the question. Dr. Spencer or Mr. Thompson, either one. I will read the question again. Does a spray containing petroleum oil at less than the lethal dosage for scale, as perhaps or percent, fortified by Parathion, hold promise of being better than oil or Parathion alone in respect to (a) less red spider followup than Para thion? I assume that means less red spider followup then when Parathion is used alone. Do you care to comment Dr. Spencer? Dr. Spencer: One of our cooperators last year had an infestation of scale and one of purple mites on some grapefruit trees. We considered the possibility of a spray combination, so we picked out one percent of oil plus two pounds of 15 percent wettable Parathion in 100 gal lons. We had no rust mites to contend with at that particular time but we did have the purple mite. We got very good results with both of those pests from that combination spray. We endeavored to kill the scales with Parathion and kill the purple mites with a one percent oil, and we accomplished this. Moderator: Thank you Dr. Spencer. Mr. Thompson do you have a comment on that question? Mr. Thompson: I might say that percent oil will give you very good purple mite control. However, wo do not know the effect of percent oil on solids. That is one thing we haven't taken up yet at the low concentrations. Moderator: Thank y_ou. There is one more question (there are three phases to it) to be directed jointly to Dr. Gleissner, Dr. Kelsheimer and Mr. Hayslip, in the field of vegetables. Dr. Gleissner: What are the comparative dangers of using one percent dust versus concen trated, to the operator? Dr. Gleissner: I might be wrong be cause of the unique citrus situation here. I believe some of you mix wettable pow

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88 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 der with your sulfur and have a one bag operation into the tank. In the case of dilute dust versus concentrate we have very little evidence as to which one is more hazardous than the other, in rela tion to the number of pounds of actual Parathion handled and applied. We do know that last year, in the case of the three fatalities in the field, the major causes of death, especially two of them, were associated with the very careless handling of the concentrated wettable powder . Provided that the concentrates are handled safely, once the material is in the spray tank, I can see no differ ence in using a concentrate or a diluted material. The important thing is to stay out of both of them. Moderator: Thank you Dr. Gleissner. Now, Dr. Kelsheimer, may I as k you this question: What causes Parathion dust or spray to injure plants of certain kinds and not others? Dr. Kelsheimer: I don't know if I can properly answer that question. We do know we can get injury from dust on wet foliage or foliage heavy with dew, particularly with tomatoes or cucurbits. Moderator: That finishes that phase of the question. Thank you very much . Will any other member of the panel care to comment on that question? Appar ently not. The next phase of the ques tion has been answered already, possi bly in full, at least to a considerable extent, but we are giving further op portunity for ,answer in deference to the member of the Society who sub mitted it. Mr. Hayslip, what is the present status for sweet corn insects (I assume that means the present status of use of Parathion in controlling in sects, for the whole forum is on Para thion). Would you care to answer? Mr. Hayslip: I believe I answered that before. I will simply say th a t Para thion definitely looks promising for South Florida , especially on certain phases of the insect problem . Mod e rator: Thank you very much . This question I would like to direct to Dr. Spencer. This may have been answered to your complete satisfaction earlier, if so, tell me so. Where does Parathion fit into the cit rus spray schedule today? Dr. Sp e ncer: We have used it almost every month of the year. And it com bines very nicely with the regular rust mite application so when the scales ap pear and we w a nt to put on a rust mite application, we add Parathion to the wettable sulfur. That mixture allows us to drop out the extra oil application recommended in the spray schedule for scales. Moderator : Thank you. The next question I would like to direct to Mr. Thomp s on. It previously has been answered b y various comments from panel member s but perhaps somebody would like to have a positive statement on it. Does Parathion control purple mites? Mr. Thompson: Parathion does not control purple mites in the sense that we think of. For instance, it does kill the active mite s ; it does not kill the eggs, nor does the residual spray m a terial remain toxic long enough to kill the young mites after the eggs hat c h. However if only a n occasional mite can be found and eggs are not numerous a Parathion spray may keep the purple mite population down to a minimum for four to six week s . Where Parathion was applied in February when only a few mites were pre s ent there was still a low popul a tion of mites eight week s later compared to a medium to heavy infestation on adjacent trees where the Parathion was omitted from the spray. If purple mites a nd eggs are numerous at the time of application then a rein

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CONOVER: NEW TOMATO FUNGICIDES 89 festation may be expected within one to two weeks. Moderator: Thank you Mr. Thomp son. Our time has been consumed and we have been requested to make an an nouncement. This information about Parathion which we have discussed will be published in the Proceedings. The moderator would like to express appre ciation for all members of the panel for your patience in this rather lengthy proposition. I am confident that each and every one of you feel indebted to these 22 gentlemen at the table here who have come from their businesses and homes and work to come, not only to be with you on this panel this morn ing, but most of them have spent weeks in trying to answer questions that have been accumulated rather early after the panel was announced; and I would like to acknowledge, as moderator, their great assistance and their patience. That concludes the panel. VEGETABLE SECTION CONTROL OF LATE BLIGHT AND GRAY LEAF SPOT OF TOMATOES WITH NEW FUNGICIDES ROBERT A. CONOVER Florida Agricultural Experiment Stations Sub-Tropical Experiment Station Homestead Since the demonstration by Ruehle (1) that nabam* plus zinc sulfate provided outstanding control of late blight (Phy tophthora infestans DBy.), this fungi cide has been widely adopted by tomato growers throughout Florida. Even though this material has given excellent results, fungicide testing has continued at the Sub-Tropical Experiment Station with the aim of finding new and more effective fungicides. This paper is a re port of the results of experiments with tomato fungicides conducted at Home stead during the seasons of 1948-49 and 1949-50. All data were obtained from field plots, each containing 36 plants. All treatments were randomized and replicated four times. The plots were 0 se~ footnote, Table I. sprayed with a tractor-drawn power sprayer operated at a pressure of 400 pounds at the pump. Three to 11 noz zles per row were used as needed accord ing to plant size. Cultural care of the plots approximated commercial practice common in the area. Insects were con trolled by separate blanket applications of recommended insecticides. The first experiment was set out on November 17, 1948, with Grothen Globe tomatoes. Fungicides were applied every seven days, a total of 11 applications being made during the experiment. Foliage diseases did not appear until the first picking when gray leaf spot (Stem phyliurn solani Weber) appeared. This disease spread rapidly and did consider able damage in the check and in plots sprayed with ineffective materials. Late blight and early blight ( Alternaria solani (Ell. and Mart.) Jones and Grout) were found in the checks but only in trace amounts and did not influence the yields. The treatments used, disease

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90 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 readings, and yields are presented in Table 1. It is clear from these data that the nabam treatments, zineb A and magne sium ethylenebisdithiocarbamate plus zinc sulfate gave excellent gray leaf spot control. CR 305, Phygon XL, Copper Compound A, Copotox and zineb B failed to give commercial control of gray leaf spot in this test. It should be men tioned that observations made in this and other experiments with this particular lot of zineb B indicated it to be sub standard. These data strongly confirm the data obtained by Walter (2) from experiments conducted at the Vegetable Crops Laboratory. The second test of the 1948-1949 sea son was set out January 13, 1949. Fungi cides were applied twelve times on a schedule varying from four to seven days with fluctuations of disease intensity. Late blight was present in the plots during most of the test; however, it was comparatively mild and caused little damage in plots other than the check. From the data presented in Table 2, it is clear that while all treatments were much superior to the check there were no significant differences among fungi cides either with respect to yield or late blight control. Only one experiment was conducted during the 1949-50 season but late blight was rampant during the test and thus offered an opportunity to evaluate the fungicides under unusually rigorous con ditions. The Missouri S-34 tomato used in this test appeared to be more suscep tible to late blight than standard com mercial varieties. The plants were set out January 3, 1950. The plots were sprayed 20 times, the first application being made on January 11 and subse quent applications being applied at inter vals of two to six days. Late blight was TABLE 1. INCIDENCE OF GRAY LEAF SPOT AND YIELDS OF MATURE-GREEN GROTHEN GLOBE TOMATOES FROM THE FIRST FUNGICIDE TEST, 1948-49 SEASON. FIGURES ARE AVERAGES OF FOUR REPLICATES. Marketable Material and Amount Used per 100 Gallons Gray Leaf Yield in Spot Count' Bu./Acr e 1. Zineb A 2 (2 lb.) 2.6 329.8 2. Nabam A 2 (2 qts.), ZnSO, (1 lb.), lime (0.5 lb.) 1.5 327.4 3. Nabam B 2 (2 qts.), ZnSo. (1 lb.), lime (0.5 lb.) 2.0 326.5 4. No. 2 alternated with No. 11 13.2 310.7 5. CR 305 (2 lb.) 29.2 309.5 6. Nabam A 2 (2 qts.), ZnSO, (1 lb.) 1.7 304.4 7. Magnesium ethylenebisdithiocarbamate (2 qts), ZnSO, (1 lb.) 2.2 302.0 8. No. 9 first 8 applications, then 3 applications of No. 2 19.2 281.7 9. Copper Compound A (4 lb.) 39.0 274.2 10. Copotox (4 lb.) 53.9 269.6 11. Phygon XL (0.75 lb.) 28.9 266.2 12. Zineb B 2 (2 lb.) 20.8 265.0 13. Check 68.3 180.8 Difference necessary for significance 12.5 70.7 1 Average number of spots per leaflet. Nabam and zineb are generic names adopted by the American Phytopathological Society for fungicides con taining, respectively, the sodium and zinc salts of ethylenebisdithiocarbamate. Nabam A= Dithane D14; nabam B = Parzate Liquid; zineb A = Dithane Z78; zineb B = Parzate.

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CONOVER: NEW TOMATO FUNGICIDES 91 TABLE 2. INCIDENCE OF LATE BLIGHT AND YIELDS OF MATURE-GREEN GROTHEN GLOBE TOMATOES FROM THE SECOND FUNGICIDE TRIAL, 1948-1949 SEASON. FIGURES ARE AVERAGES OF FOUR REPLICATES. Material and Amount Used per 100 Gallons 1. SR 406 (4 lb.) 2. No. 6 alternated with No. 4 3. Magnesium ethylenebisdithiocarbamate (2 qts.), ZnS0. (0.75 lb.) 4. Phygon XL (0.75 lb.) 5. Copper tetramethylthiuramdisulfide (2 lbs.) 6. Nabam A 2 (2 qts.), ZnSO, (1 lb.), lime (0.5 lb.) 7. Nabam A 2 (2 qts.), ZnSO, (0.75 lb.) 8. Nabam B 2 (2 qts.) ZnSo, (0.75 lb.) 9. CR 305 (2 lb.) 10. Check Difference necessary for significance 1 Average number of lesions per plant, March 4, 1949. See footnote, Table I. TABLE 3. Marketable Late Blight Yield in Data 1 Bu./ Acre 1.2 275.4 0.2 249.8 0.2 249.8 0.5 248.4 3.7 246.8 0.3 246.4 0.3 236.0 0.3 235.8 2.7 226.4 35.7 116.4 13.8 52.8 INCIDENCE OF LATE BLIGHT AND YIELDS OF MATURE-GREEN MISSOURI S-34 TOMATOES FROM THE FUNGICIDE TRIAL OF THE 1949-50 SEASON. FIGURES ARE THE AVERAGES OF FOUR REPLICATES. Treatment and Amount Used per 100 Gallons 1. Zineb A 3 (2 lb.) 2. Zineb C 3 (2 lb.) 3. Zineb B 3 (2 lb.) 4. Zineb D 3 (2 lb.) 5. Phygon XL (0.75 lb.) 6. No. 8 alternated with No. 5 7. Nabam B 3 (2 qt.), ZnSO, (0.75 lb.) 8. Nabam A 3 (2 qt.) ZnSO, (1 lb.), lime (0.5 lb.) 9 Nabam A 3 (2 qt.) ZnSO, (1 lb.) 10. HL 446A (SR 406) (5 lb.) 11. Tribasic Copper Sulfate (4 lb.) 12. Copper tetramethylthiuramdisulfide (2 lb.) 13. P 111-5 (1 pt.) 14. Check Difference necessary for significance 1 Total number of stem infections found on ten plants, March 9, 1950. 2 Percent of total yield showing late blight infection. Late Blight Counts Marketable Stem Yield in Cankers 1 Fruit 2 Bu./Acre 1.8 0 342.0 4.0 0.27 308.8 3.3 0.10 297.8 5.3 0.42 293.4 5.0 0.08 288.6 2.3 0.07 288.2 3.5 0.09 263.6 4.3 0.22 259.4 6.8 0.10 254.8 19.5 0.84 227.0 54.3 2.17 105.2 41.8 5.07 93.6 34.3 16.88 28.4 86.5 28.24 10.4 10.5 2.67 54.4 See footnote, Table I. Zineb A = Dithane Z78; zineb B = Parzate; zineh C = Dithane Z78 M6A; zineh D = Dithane Z78 M4A; nabam A= Dithane D14; nabam B = Parzate Liquid.

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92 FLOIUDA STATE IIOHTICULTUHAL SOCIETY, 1950 present on a few plants before spraying was begun and was active throughout the test. The data obtained from this experiment (Table 3) show that Phygon XL and the nabam and zineb treatments were outstandingly effective in controlling late blight. While these materials as a group outyielded all others, the zineb sprays and Phygon XL were superior to the nabam treatments. HL 446A gave good control of late blight, but not equal to that obtained from the above mentioned materials. Tribasic Copper Sulfate, copper tetramethylthiuramdi sulfide and P 111-5 all failed to control late blight and yields from plots spray ed with these fungicides were very low. For the first time in several years of testing in the Homestead area, the nabam sprayed plots exhibited injury in the form of leaf roll, marginal chlorosis and stunting. It seemed likely that the reduced yields of these plots compared with zineb sprayed plots were due to this injury. The use of lime in one of the treatments failed to alleviate the injury; however, it was barely notice able in the treatment alternating Phy gon XL with nabam. This damage, which was also observed in some late commercial fields of the Grothen Globe variety, may have resulted in part from the heavy residue built up from fre quent spraying in the absence of ap preciable rain. An injury to the cuticle and epider mis of the fruit was observed in certain treatments of the late test of the 194849 season and in the test of the 1949-50 season. This injury was seen initially on small fruit about one-half inch in diameter when it appeared as minute, roughened spots that were easier felt than seen. These were often found to be directly under dried droplets of spray. As the fruit enlarged the spots became larger and more prominent, per haps being aggravated by additional sprays. On mature-green fruit the spots were up to one-fourth inch in diameter. At this stage the affected areas were corked over much as seen in scarred fruit but differed in that the areas were round and often were ob viously distributed over the fruit in typical spray-droplet pattern. There was great variability in the number of spots, their size and distribution, al though most were usually found on one side of the fruit. These spots usually did not interfere with ripening and did not result in the rotting of the fruit unless secondarily infected. In both of the tests referred to, this damage was observed in all plots sprayed with the nabam treatments and with HL 446A (SR 406). In the alter nating Phygon XL and nabam schedule the damage was appreciably less; no injury resulted from the use of Phygon XL alone. The injury was not ob served in other treatments. In the 1948-49 test, approximately 35% of the third picking of Grothen Globe toma toes exhibited this injury, much of it severe enough to make the fruit un marketable. In the 1949-50 test the damage was less severe with about 5 % of the total yield of the Missouri S-34 tomato being affected. It is interesting to note that the zineb sprays, which provide the same fungicide as nabam plus zinc sulfate, did not show this injury. This damage has also been observed by Walter in the Manatee-Ruskin area (3). Observations made at Homestead and on the West Coast by Walter indi cate there is considerable variation in the amount of injury displayed by dif ferent varieties. It is hoped that work this season at the Vegetable Crops Laboratory and at the Sub-Tropical Ex periment Station will result in infor mation that will provide an understand ing of just what causes this injury and how it may be avoided.

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WOLFENBARGER & KELSHEIMER: FERTILIZER-INSECTICIDE COMBINATIONS 9 3 LITERATURE CITED l. RUEHLE, GEo. D. Out s t an ding potato late blight control in Florida with a new organic fungicide combined with zinc sulfate. Plant Dis ease Reporter 28: 242-245. 1944. 2 . WALTER , J . M . C o ntrol of Gray Leaf Spot o f Tomato. Mark e t Growers Journal, pp. 19-29. 1948. 3. WALTER , J. M . Unpublished data. FERTILIZER-INSECTICIDE COMBINATION FOR ARMYWORM, MOLE-CRICKET AND WIREWORM CONTROL D. 0. WOLFENBARGER Flo1 daAgricultural E x p erime nt Stations Sub-Tropical Experiment Station Homestead and E. G. KELSHEIMER Florida Agricultural Experim e nt Stations V e getable Crops Laboratory Bradenton . Interest in combining insecticides with fertilizers is much greater than it was four years or more ago. The sig nificance of this lies in combining field operations in order to save labor. The idea of combining insecticides with fertilizers is closely associ a ted with the development of the new organic insec ticides. The potentialities of combin ing insecticides with fertilizer appear extensive, but it is well to recognize our dearth of knowledge in the matter. Factors for Consideration The objective of an insecticide-fer tilizer combination is to control soil inhabiting insects and to provide for the nutritional requirements for the plants treated all in one operation. This operation may not be as simple as it appears. The use of two materials in volves many factors which must be considered before widespread success ful performances will be secured. It is assumed, fol:" purposes of this discussion that the kind, amount and other factors regarding the fertilizer are known. This leaves the problems of mixing, compatibility, and results to be discussed. Definite entomological factors to be considered include the following: insect to be controlled, in sects that may increase after the appli cation of an insecticide, compatibility of the insecticide and the fertilizer, reactions and interactions of the soil with the insecticide-fertilizer combina tion. The authors have observed the effec tiveness of insecticide-fertilizer com binations for mole crickets, cutworms , white grubs, ants, earwigs, chinch bug, and wireworms. Mole crickets, cut worms, earwigs, and chinch bug are recognized as surface feeders. Less insecticide per acre is needed for con trol of surface feeding insects than for insects which forage beneath the sur face, such as wireworms and white grubs. Although the amount of insec ticide is given on the acre basis for both surface and subterranean feeding insects, the third dimension, depth, re quires increased amounts of the toxi cant for subterranean insects. It is recommended that the use of an insecticide-fertilizer combination be governed by the insect problem in volved. There is waste, and a pos sibility of achieving harmful results, in applying the insecticide-fertilizer com bination indiscriminately in the hope of getting some benefits unless a problem exists. If one has a soil surface or subterranean insect problem and if the

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94 FLORIDA STATE HORTICULTUHAL SOCIETY , 1950 timing of the fertilizer application may coincide with the need for an insecti cide, the two may be combined and used with a saving of labor and equipment. Insecticides Mixed with Fertilizer The newer insecticides tested with fertilizer include DDT, chlordane, ben zene hexachloride, toxaphene, lindane, aldrin, parathion, and dieldrin. Some insecticides are more useful for certain insects than for others. A number are, however, equal in effectiveness on a number of insects, hence, become com petitive. The user may mix whatever insecti cide he may desire with fertilizer. The Department of Agriculture, State of Florida, however, has regulations gov erning the combinations of chlordane, DDT, benzene hexachloride, and lin dane mixed for sale (Florida Com mercial Fertilizer Law, Chap. 576, Flor ida Statutes, 1949, Sec. 576.09, Tech. Reg. No. 5). Mixing the Components Combining insecticides with fertil izers has been accomplished by simple mechanical mixes. Most mixing is done by formulators, manufacturers, or deal ers, although it may be done by hand. The insecticidal material is usually added to the fertilizer and stirred thor oughly by hand or by machines. Some industrial processes permit mixing the insecticides and the different fertilizer components simultaneously. No differ ences have been recognized in the man . ner of mixing. Rate of Mixing and Application Confusion and dissatisfaction may result unless some knowledge and at tention is given to the amount of insec ticide; in terms of active ingredient, used. A mix of one pound active ingredient of chlordane and of DDT per 200 pounds of fertilizer applied per acre gives com mercial control of mole crickets, chinch bugs, earwigs, cutworms, and will re duce ant populations. In wireworm control on potatoes, on the highly alkaline Perrine marl soils, 4.3 pounds chlordane, active ingredient; in 1500 pounds of fertilizer per acre gave 82 percent control. Aldrin, at 2.2 pounds active ingredient in 1500 pounds of fertilizer per acre gave 88 percent control. The combinations were ap plied as the potatoes were planted, in bands, two inches wide, two inches at each side, and one inch below the row. Experimental results showed that chlordane and aldrin applied broadcast gave more effective control, pound for pound of active ingredient per acre, than the same materials applied with fertilizer. Wireworm control reported by Pepper, et al, (1949) showed similar results where benzene hexachloride was applied. Neither benzene hexachloride nor lindane can be recommended for use on potatoes nor on soil where potatoes will be grown, because of the objection able off-flavor in the tubers. Inclusion of 0.5 pound of actual chlor dane per 50 gallons of starter solution on tomatoes has been reported by grow ers as giving satisfactory wireworm and cutworm control. Chlordane, DDT, benzene hexachlor ide, and lindane are useful on lawns, golf courses, and among ornamental shrubs and trees for chinch bugs, mole crickets, and certain other insects at the rate of one pound active ingredient per acre. Plant Injury, Seed Germination and Growth Chlordane has been used in amounts up to 50 pounds of active ingredient per acre on seedbeds on Bradenton sandy loam soil without any injurious effects to cabbage, lettuce, tomato, eggplant, and pepper. Benzene hexachloride at

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WILSON: TOXIC RESIDUES 95 two and one-half and five pounds of five percent gamma-isomer content per 50 gallons of starter solution, as used on tomatoes, injured tomato plants. DDT has been safe to plants in soil applications at dosages up to 200 pounds per acre. Aldrin has been safe to potato plants up to four pounds active ingredi ent per acre in combination with fertilizer. TOXIC INSECTICIDE RESIDUES OF VEGETABLES J. W. WILSON Florida Agricultural Experiment Stations C e ntral Florida E x p e riment Station Sanford The hearings conducted by the Food and Drug Administration on chemicals used for pest control in fruit anc} vege table production were completed in late September. It is expected that tenta tive tolerances will be announced dur ing the early spring of 1951. The pro mulgation of these tolerances is of primary interest to every one connected with fruit and vegetable production, from the grower to the distributor and manufacturer of pesticides. These hearings and the restrictions on the amounts of insecticides to be tolerated on fruits and vegetables have served to focus attention upon the means of avoiding excessive residues. It is gen erally conceded that the use of insecti cides is absolutely e s sential in the economic production of market-accepta ble fruits and vegetables. Entomolo gists' efforts are directed toward de veloping effective means of insect control which require a mm1mum amount of poisonous insecticides. When a new chemical is under investi gation as a possible insecticide it is necessary to conduct a lengthy and detailed study of the chemical before it is released for experimental trial. Among the factors which are studied during the preliminary investigations are: (1) the effectiveness of the chemi cal against several different types of insects, (2) the reaction of plants to the chemical, that is , whether or not plants are injured by the material un der a variety of conditions, (3) the compatibility of the chemical with other insecticides and fungicides, and (4) the acute and chronic toxicity of the chemical to small animals and man. If the chemical still shows promise after the preliminary investigations it is re leased for experimental trials under a wider range of weather conditions against a large number of insects on many crops. After it has passed these tests the chemical is ready to be placed on the market for general use. Thus the development of a new insecticide is a long and expensive process. We may then define the ideal insecticide as one which has a high toxicity to a wide range of insects, will not injure plants, can be readily mixed with other insec ticides and fungicides, has an optimum degree of persi s tence and is not toxic to human beings. The insecticides which have come into use in recent years have many of the desirable char acteristics of an ideal insecticide, but most of them are highly toxic to hum a n beings. For this reason these insecti cides must be used cautiously in order to avoid injury to those who apply the insecticides and those who consume the treated vegetables. If the necessary precautions are ob served the possibilities of acute poisoning are rather remote. But the possibilities of chronic poisoning, resulting from the consumption of foods contaminated with small quantities of cumulative poison over a long period of time, are of great

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96 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 concern to everyone. Thus it becomes important to know the amount of these various insecticides which may be ex pected to remain on vegetables treated for the control of insect pests. There are a number of factors which in fluence the amount of residues found on treated vegetables and a knowledge of these factors will assist in the avoid ance of excessive residues. One of these factors is the chemical nature of the insecticide itself. For example, tetra ethyl pyrophosphate (TEPP) hydrolizes rapidly in the pres ence of water so that within twenty-four hours very little or no TEPP is present. On the other hand, parathion, another of the phosphate insecticides, is stable in the presence of water and is much more persistent than TEPP. In the case of the chlorinated hydrocarbon insecticides, Decker et al. (2) have shown that the volatility of the insecti cide has a considerable influence upon the amount of the original deposit of the insecticide and thus influences the amount of residue. Of the insecticides they worked with, DDT gave the great est original spray deposit, followed, in the order named, by toxaphene, dieldrin, aldrin, chlordane, parathion and lin dane. In the selection of an insecticide, especially in cases where it is to be used during the latter part of the growing season, the chemical nature of the mate rial should be given consideration. Another important factor which in fluences the amount of residue that may be found on treated vegetable crops is the physical nature of the insecticide. Decker (2) and his co-workers, in the paper already referred to, also reported that chlordane and toxaphene are much more resistant to the washing effects of heavy rainfall than DDT, dieldrin and aldrin. In a duplicate series of tests on alfalfa a heavy rain of 2.33 inches fell on the third day on one series of plots, while there was no rainfall for seven days on the other series of plots. As was to be expected, all of the insec ticides showed a greater loss following the rain than where there was no rain. This ability of chlordane and toxaphene to resist the washing effect of heavy rains was attributed to the fact that DDT, dieldrin and aldrin are drier than chlordane and toxaphene. A third factor, which influences the amount of residue, is the formulation used. Most present day insecticides are prepared as dusts, wettable powders and emulsifiable concentrates. In each of these types of formulations there is a wide range of diluents, wetting agents, deposit builders, solvents, etc. which may be used. The materials which are used in the manufacture of an insecticide have chemical and physi cal properties that will affect the amount of the original deposit of the insecticide and its weathering charac teristics. Hoskins ( 4), reporting on work in California, shows that residues following the use of dust formulations are much lower than following the use of wettable powder sprays. Similar results were reported from Illinois by Decker et al (2). Under weather conditions may be grouped rainfall, light and temperature conditions. The washing effects of rainfall have already been mentioned in connection with the physical properties of the insecticide. It is also obvious that the amount and the rate of rain fall will affect the amount of insecticide residue. Lindquist et al. (5) studied the effect of ultraviolet light and sunlight on solutions, emulsions and suspensions of DDT. Exposure to both ultraviolet light and sunlight materially reduced the effectiveness of the DDT. This re duction in effectiveness was greatly ac celerated when high-boiling auxiliary solvents were used as contrasted wth the low-boiling solvents. Xylene emul sions and water suspensions were less

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WILSON: TOXIC RESIDUES 97 affected by light than solutions. As a result of their study of the effect of temperature and humidity upon resi dues of DDT, Burgess and Sweetman (1) concluded that high temperatures and high humidity markedly, reduced its effectiveness against house flies. Treated screens, held at 23 C. and 25 to 40 percent relative humidity, re mained highly toxic to house flies for a period of thirty-nine months, whereas similarly treated screens, held at 37 C. and 60 to 75 percent relative humidity, caused a very low mortality of flies at the end of this period. Gaines and Dean (3) used the boll weevil as the test insect to study the effect of tem perature and humidity upon the toxicity of calcium arsenate, toxaphene, chlor dane and a mixture of 3 percent gamma benzene hexachloride-5 percent DDT. High temperature and high humidity affected the toxicity of toxaphene less than the other organic insecticides. High temperature alone reduced the toxicity of all the insecticides, with the toxicity of clordane being reduced more than the toxaphene or the mixture of benzene hexachloride and DDT. At constant temperatures and high humid ity the toxicity of both toxaphene and chlordane were reduced. Robinson (6) has presented data to show that the processing required in the preparation of certain vegetables for market will reduce the amount of insecticide residue. For example, beans treated four days before harvest with 3 percent DDT at the rate of thirty pounds per acre carried a residue of 1.1 p.p.m. of DDT, while beans receiving the same treatment and canned by the usual cannery process carried 0.7 p.p.m. of DDT. Cauliflower treated with 0.5 percent parathion dust at fifty pounds per acre, seven days before harvest, carried a residue of 0.21 p.p.m., while cauliflower receiving the same treat ment and washed and blanched for freezing carried 0.04 p.p.m. of para thion. The time elapsing between the last application of the insecticide and har vest is the most important of all the factors which influence the amount of residue. The longer the time period the smaller the amount of residue remain ing because of decomposition, volatili zation and erosion. During the past year determination of residues on Florida grown vegetables was started at the Central Florida Ex periment Station. It was necessary to spend last year in preliminary studies and for this reason only a very limited amount of data on insecticide residues on Florida grown vegetables is avail able. This work is being continued at the main Station in Gainesville. The available data is from a small number of samples of pepper, cabbage, and celery from p1ots treated with para thion sent to the American Cyanamid Company Laboratory and samples of celery from plots treated with toxa phene sent to . the Hercules Powder Company Laboratory. Results of these analyses are presented in table 1 and table 2. The first sample of pepper was taken from a plot treated by means of hand duster and the second sample from a field treated by means of a six row power duster. Eight hours after the power duster application a heavy rain fell on this field and a second rain fell twenty-four hours later. The cab bage received two applications of 1 per cent parathion dust on March 16 and April 8 by means of a hand duster. The parathion and toxaphene were applied to celery by a six row power sprayer. The pepper and cabbage samples were not washed. Part of the celery samples were taken to a commercial packing house and given the usual washing and part of them were unwashed. Although the number of samples is small the data on parathion is in accord with pub

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98 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 lished data from other sections showing that when there is a period of as much as thirteen days between the last appli cation and harvest very little parathion residue is found. The toxaphene resi dues on celery given in table 2 show the effect of washing as the washed and unwashed samples at each dosage level were taken from the same plot. LITERATURE CITED 1. BvnGESS, A. F. and SWEETMAN, H. L. The residual property of DDT as influenced by tem perature and moisture. ]our. Econ. Ent. 42: 420-423. 1949. 2 . DECKER , G. C., WEINMAN, C. J., and BANN, J . M. Exhibit 904 A preliminary report on the rate of insecticide residue loss from treated plants. Mimeographed by Julius Hyman & Company . 1950. 3. GAtNES, J. C. and DEAN, H. A . Effect of tem perature and humidity on the toxicity of certain insecticides. ]our. Econ. Ent. 42: 429-433. 1949. 4. HOSKINS, W, M. Deposit and residue of recent insecticides resulting from various control prac tices in California . ]our. Econ. Ent. 42 : 9669 7 3 . 1949. 5, LmDQUIST, A. W., JONES, H. A. and MADDEN, A. H. DDT-residual type sprays as a ff ec t e d by light. ]our. Econ. Ent. 39: 55-59. 1946. 6, ROBINSON, R. H. Spray residues on food crops and their relation to total food consumption, Am e r . Chem. Soc. Adoances in Chem . Series 1: 49-52. 1950. TABLE l. RESIDUES OF PARATHION ON PEPPER, CABBAGE AND CELERY. ANALYSES Crop Pepper Pepper Cabbage Cabbage Cabbage Celery Celery Celery Lbs. per Acre of Toxicant 14.4 10.3 1.8 6.0 4.2 BY AMERICAN CY\NAMID COMPANY. Lbs. per Interval B e tween Insecticide Acre, Toxicant Numb e r Last Application Residue in Applied Applied Applications and Analysis, P . P.M . Days 1 % Parathion 0.8 Dust 2 13 None " 0.18 1 2 None 1 % Parathion 0.9 2 3 3.7 Dust " " " 13 0.4 " " " 21 0.2 lb . 25 % Wettable 0.25 2 3 0.5 Parathion 20 0.1 0.37 3 55 0 TABLE 2. RESIDUES OF TOXAPHENE APPLIED AS A SPRAY OF THE 40 % WETTABLE POWDER TO CELERY. ANALYSES BY HERCULES POWDER COMPANY. Interval Residue in P. P. M. Number Between Last Applications Application Unwashed Washed and Harvest, Days Stalk Foliage Stalk Foliage 10 12 1.6 9.8 9 13 2.6 19.7 1.8 6.5 2 47 0 0.2 0 0 3 31 0.2 2.9 0 0 3 31 0 0 0 0

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VAN HORN: PESTICIDES 99 PROCESSING AND LABELLING PESTICIDES M. C. VAN HORN Florida Agricultural Supply Company Jacksonville Mr. Chairman, Gentlemen ... it is an honor and a pleasure to appear before you today. It is an impressive audience that I face. An audience of technical specialists who have made a terrific con tribution to Florida's agricultural wealth ... men who are basically responsible for the fact that the state of Florida today boasts nearly 62,000 successfully operated farms occupying 13 million acres of land with farm land and buildings valued at nearly five hundred millions of dollars. Every year-every month, in fact, more and more of Florida's wastelands are becoming veritable Gardens of Eden. Out of the desolate mucklands, the horti culturists have brought untold wealth in sugar cane and celery; out of the drift ing sand hills they have created fortunes and improved national health with rec ord breaking yields of superb citrus. Florida is everlastingly indebted to her horticulturists. The dictionary, by the way, defines horticulture as "the science and art of cultivating garden plants." I guess that's right. However, I don't see any dungarees or overalls in front of me. So perhaps we are "gentlemen farmers."-They tell me that a gentle man farmer is one who never raises any thing but his hat. I have been asked to speak to you to day on the subject, "Processing and Labelling Pesticides." It's a subject on which I could and sometimes do-spout all day but-I don't think I'd get away with it today. As a matter of fact, the last time I made a speech about pesticides I heard the chair man of the meeting say afterward "That fellow Van Horn doesn't go by his watch when he talks about pesticides -he uses a calendar." In the production of modern pesticides, the procurement of the highest quality raw materials is an important factor. But even the best raw materials do not necessarily insure or guarantee the pro duction of a quality, effective and safe finished processed product. Even more important than materials are the knowl edge and experience peculiar and specific to the profession-the art, if you please -to say nothing of the equipment and other plant facilities essential to the process. For example-cooking is a science but still there is an art to it. Give two housewives comparable ingredients with which to bake a cake. One will tum out a delectable, gustatory delight. The other will produce a product that even the chickens won't eat ... Which proves, I guess, that some women can dish it out but they can't cook it. And there is nothing more exasperating than a wife who can cook and won't-unless it's a wife who can't cook and will. Aside from that-this same "art" ap plies to the production of pesticides. There must be a "know how"-which is available neither in textbooks nor the Book of Knowledge. It is a "know how" acquired through years of research, ex perimentation and the reliable old system of trying, trying and trying again. The physical and chemical properties of each ingredient which enters into the product must be carefully studied, with due consideration given to the final pur pose, or objective, of this particular product, and the manner in which it will be applied. Among the factors which research chemists, entomologists and plant patho logists must consider in compounding and processing a pesticide are these:

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100 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Dry Materials A. Particle size. B. Comparative density of compo nents. C. Ph of components and end product. D. Shelf or storage life-chemical and physical. E. Dustability of dusts. F. Wettability of dry wettable powders. G. Suspendibility of dry wettable powders. H. Adherence and weathering quali ties. I. Foaming tendency. J. Compatibility with other products. K. Suitable package requirements. L. Effects of material on equipment. M. Effects of material on pest and host. N. Hazards in handling. 0. Create synergistic action if pos sible. P. Buffer against refractory waters and varying ph. And I repeat-these are only some of the factors which must be considered. Liquid Materials When it comes to processing liquid formulations, most of the points I just listed must be coni;idered, with the ex ception of such items as particle size, dustability, wettability and suspendi bility. However, in dealing with liquid materials, new factors arise .. . such as solubility, stability, and emulsifiability. In most cases, solvents, detergents emulsifiers, wetting agents ' and adju vants are employed in processing. These ingredients must not only per form their function in processing but they must also be non-inflammable, host-safe and effective against the pest. In all cases it is desirable for the toxi cant to remain viable sufficiently long to be lethal to the pest. In some cases, long lasting residues are desirable and in other instances, this is a disadvan tage. Virtually the same basic requirements apply to those pesticides which are propelled by gas or liquid under pres sure as those which apply to liquids. In the preparation of baits, it is es sential to obtain a food which is readily acceptable to the pest. The toxicant must not be repellant to the pest to the point where the pest will avoid the bait or fail to eat a lethal dose. Then there is the problem of keeping the bait in a palatable condition. Most baits con tain material toxic to warm blooded animals and here again we have another problem-that of proper distribution and the establishment of safeguards against wanton poisoning of desirable species. Certain solvents as may be used in liquids, diluents as may be us , ed in dusts, wetting agents as used in dry wettable powders, may be in themselves toxic to either plant or animal life or both. In general, processed products may be classed as solutions, mechanical mix tures, gasses, impregnations, solids, suspensions and emulsions. Solutions are usually made by various methods employing heat, solvents, etc . Mechanical mixtures result from grind ing and blending of previously fine ground materials. Impregnations are effected by atomizing liquids or solu tions on to a dry absorbent base. Gasses are usually produced by prime pro ducers. Baits may be either mechanical mixtures or impregnations. Emulsions and suspensions are usually produced by such mechanical devices as pumps, agitators, colloid mills or homogenizers. In modern processing adequate equip ment to do the job is paramount. This is especially true insofar as dry ma terials are concerned and specifically

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VAN HORN: PESTICIDES 101 with dusts. Not only is the degree of fineness a critical factor but an inti mate, complete and thorough dispersion of the actives must be obtained especial ly in the mechanical mixture. This can only be accomplished by the most careful control of adding raw materials to be compounded through equipment which is adequate to accom plish the desired results. Simple mix ing by means of a ribbon mixer, which is the process used by some blenders, all too frequently results in inferior dust blends. To insure quality products, it is vitally important that chemical and physical control be in effect at all stages of production-this control to cover both the raw materials and the finished processed product. The improper physical or chemical processing of a pesticide can be respon sible for a r _ eduction in the efficacy of the product below that which would normally be expected of it. By the same token, special processing not only can, but has been proved by demon stration to enhance the control value of the product beyond the expected normal. We will now assume that the pro cessed product has run the grim gaunt let that I have outlined , has met the prescribed tests and is now ready for labelling. You know what they say about books -that some books sell by their label others by their libel. That doesn't apply to pesticides. The labelling of pesticides is a vitally im portant part of the intelligent use of the product. Incidentally, the practice of branding commercial goods dates back to the Middle Ages, specifically in Turkey. At that time, the proud producers of goods distinguished one from another by the term "Hallmark." The modern version of the "Hallmark" is Trade-Mark, or Brand Name of the product. This is usually a part of every label. There are at least twelve important points to consider in the preparation of product labels. The label should clear ly and plainly give the following infor mation: 1. Name of product. 2. Analysis statement as to ingredients. 3. Manufacturer and address. 4. Brief description of product. 5. Pests controlled and dilution. 6. Hosts on which to be used and rate. 7. Precautions as to handling and use. 8. Warnings as to hazards to appli cator and/or host. 9. If poison-the word poison with skull and crossbones, both in red, should appear on label. 10. Antidote and/or treatment should be given for all toxic materials. 11. If materials are inflammable this should be so stated. i2. Net contents of each package. All this information should be printed in a non-technical language, easily read and understood by the lay man. All labels should be of such size that they can be readily seen. They also should be placed on an accessible smooth portion of the container. Such labels should remain on the package until it reaches the consumer. It is highly undesirable to break a labelled package and deliver unlabelled pesti cides to a customer. With the great number of new pesti cides now in the field it is not only im perative that they be properly and com pletely labelled but it is also highly desirable that those who recommend and use the products should read and understand them, as some of these products are highly toxic to warm blooded animals; whereas, others can

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102 FLORIDA STATE HORTICULTURAL SOCIETY, 19.50 result in other forms of host toxicity if improperly used. Well, gentlemen-that is a base canard they have spread about me. Here it is-still November the first and I am through talking. As a matter of fact, I am intentionally cutting this talk short. Just before I came up here on the platform, the chairman asked me if I knew the defini tion of an audience and before I could reply he said, "An audience is some thing that you should leave before it leaves you." THE ROLE OF THE REGIONAL VEGETABLE BREEDING LABORATORY IN BREEDING AND TESTING NEW VEGETABLE VARIETIES S. H. YARNELL U. S. Regional Vegetable Breeding Laboratory Charleston, South Carolina For those who may not be familiar with the purpose and organization of the Regional Vegetable Breeding Labo ratory, let me say that it was estab lished in 1936 to aid in the development of improved varieties of vegetables for the South in collaboration with the 13 Southeastern States. Emphasis should be placed on cooperation with the state agricultural experiment stations, each of which, from Virginia to Oklahoma and Texas and all States south and east, has an official collaborator, appointed at the recommendation of each Station Director. As a matter of fact, cooperation among the vegetable breeders of these States and of the U. S. Department of Agriculture has developed far beyond the point of formal collaboration, to the mutual advantage of all groups. The breeding of vegetables and other plants is a rather complex process, being made up of several distinct operations. These steps include the selection of breeding materials as parents, the adoption of a system of breeding, making the crosses (which involves a wide variety of techniques according to the crop), the selection of individuals and later of breeding lines, the regional comparison of the new lines with established varie ties, and finally the increase of seed and introduction of the new variety. Some of these operations can be accomplished only by the active cooperation of a num ber of individuals. Other steps are often more effective if several workers can get together to pool their resources. A good example of the necessity for cooperation is the regional testing of promising breeding lines. Here in the South the Southern Section of the American Society for Horticultural Science has set up an organization to handle such trials. While the horti culturists initiated the organization, it is open to all station workers in the region who . are actively interested in vegetable breeding and in new varieties. It includes quite a number of plant pathologists, a few agronomists, and many horticulturists not actively en gaged in the earlier pha _ ses of breeding. The work is done by a crop chairman and a variable number of cooperators, depending on the interest in and im portance of the crop. The cooperators are usually widely scattered over the entire region. The chairman collects the several lots of seed, distributing identical sets to all cooperators. With the help of the group at annual meetings and by correspondence, he develops a set of forms for taking notes. At the

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YARNELL: VEGETABLE BREEDING LABORATORY 103 end of the season all records are sent to the chairman, who assembles the in formation for reporting to all the co operators. Where several newly intro duced varieties have been included in the trials, a report may appear in one of the trade journals. There are several advantages of such a comprehensive test to the vegetable breeder and ultimately to the vegetable grower. Information in regard to sea sonal effects on a breeding line in com parison wth a standard variety accumu lates very rapidly in the regional test. Questions of fruit size, quality, and production under adverse conditions receive a ready answer. This often pre vents the introduction of a breeding line of limited adaptability that looks good locally for a few seasons, and thus may save growers and seedsmen money and the investigators embarrassment by avoiding subsequent commercial failure. Since seedsmen quite understandably hesitate to add to their list varieties adapted to only a small area, the demon stration of wide regional a daptability for a new introduction permits its en thusiastic acceptance by the seed com panies and thus assures a seed supply more comparable to that of established varieties. Florida Station workers are making important contributions to these co operative tests. G. K. Parris, in charge of the Watermelon and Grape Investi gations Laboratory at Leesburg, has re cently assumed the chairmanship for the watermelon trials. Cooperators in the tomato work include F. S. Jamison at Gainesville, B. F. Whitner at San ford, G. D. Ruehle at Homestead, D. G. A. Kelbert and J. M. Walter at Braden ton, and Emil Wolf and Norman Hayslip of the Everglades Station, who have trials at Boynton Beach and Ft. Pierce. R. A. Conover, plant pathologist at Homestead, is making one of the sweet corn plantings this year. Other locations for sweet corn include Bradenton and Gainesville. Additional Southern Cooperative Vegetable Trials in Florida are at Sanford on English peas, by R. W. Ruprecht, at Hastings on broccoli and cabbage by E. N. McCubbin, and at the Everglades Station on snapbeans by W. A. Hills. It should be made clear that such trials are inactive on some crops, such as table beets, for which we find little or no justification at pres ent . Other crops, such as celery, are not grown in enough widely separated districts in the South to make cooperative tests feasible. To illustrate the increased effective ness of cooperation in vegetable breed ing let me cite the work on nematode resistance in the tomato. In the early thirties the Division of Plant Introduc tion of the U . S. Department of Agricul ture sponsored a trip to South America by the late H. Loran Blood, U.S.D.A. plant pathologist then located at the Utah Station. Among the vast array of tomatoes secured were several lots of a related wild species, Lycope1sicon pent vianum. Seeds of this material were distributed widely to tomato research men. In 1941 D. M. Bailey of the Ten nessee Station reported resistance to nematode in peruvianum. Unfortunately the strains 1esistant to nematode were very difficult to cross with the tomato species used commercially. Just before World War II Paul G. Smith of the Cali fornia station succeeded in growing three F1 plants of the cross Michigan State Forcing X L. peruvianum by means of embryo culture. These plants were self-sterile and appeared to be sterile in crosses with the commercial type of to mato. Since this work had to be dis continued because of the war, cuttings were sent to V. M. Watts, tomato breeder at the Arkansas Station. Watts was suc cessful in getting self-fertile plants from crosses between the nematode-resistant hybrid and other commercial varieties

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104 FLORIDA STATE IIOH.TICULTUH.AL SOCIETY, 1950 but under his conditions was unable to select pure resistant stocks. Because of this difficulty seeds of these lines were sent to W. A. Frazier out in Hawaii. Frazier and his associate R. K. Dennett were able . under conditions in Hawaii to isolate resistant lines that were "essen tially homozygous" for this character and part of the seeds were returned to Watts, who is now bringing the fruit up to commercial size. The net result is a valuable new source of nematode resist ance in the tomato. Now it could be argued that all of this might have been done at a single location by a single man, and we shall have to admit that theoreti cally it could, but experience tells us that theory and practice are here at odds. We can say that such informal coopera tion is proving to be a very effective way of getting satisfactory results. The remainder of the time will be devoted to the activities of the Vege table Breeding Laboratory working with others, particularly as they are re lated to the improvement of varieties of vegetables in Florida. The late B. L. Wade, who was in charge of the Laboratory from its incep tion until he went to the University of Illinois in September 1948, was enorm ously interested in the breeding of snap beans. A great deal of emphasis was placed on resistance to disease in beans as well as in other crops being bred at the Laboratory. In January 1940 he distributed small samples of 47 breed ing lines to bean breeders at experiment stations in the Southeast. A planting was grown at the Everglades Station at Belle Glade. Most of these beans were in the third or fourth generation of crosses between U. S. No. 5 Refugee or other varieties originated by Wade and W. J. Zaumeyer at Greeley, Colorado, and varieties common in the South. Such lines were not fully fixed in many of their characters and this gave State cooperators a chance to select for types especially adapted to each area. At Belle Glade this selection was done by G. R. Townsend, at the time plant pathologist with the Everglades Station. In the early plantings injury from the bean leafhopper was severe, and susceptible lines were attacked by rust and by powdery mildew. Of the first 47 lines grown, seven were selected, seed being saved on a single-plant basis. In 1941 five of these lines were eliminated be cause of the presence of several races of rust. The two remaining lines were named in 1943 and released to the seed trade for increase and sale to the local growers. These two breeding lines were named Florida Belle and Florida White Wax. They are resistant to the com mon races of rust that exist in Florida, to powdery mildew, and to common bean mosaic, and they are heat and drought tolerant. In addition to serving as im portant commercial varieties these two snap beans have been used in the breed ing program as parents. Their disease resistance has been transferred to sev eral hundred additional breeding lines many of which have been or are now under test in Florida. Contender, a new fresh-market snap bean, was recently introduced in co operation with the Mississippi, Florida, and Alabama agricultural experiment stations. It is expected that this bean will be of some value to the commercial growers of Florida as a shipping type. Usually about 50 percent of Contender's pods reach the No. 4 sieve size 50 days from planting. The pods are similar to those of String less Black Valentine; but under most conditions they average of an inch longer, and are slightly heavier and thicker. The pod shape of No. 3 and 4 sieve sizes is a plump oval, but pods of larger sieve sizes approach the round index and are generally classified as off-round. No significant difference has been found between the curvature of the Contender and String

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YARNELL: VEGETABLE BREEDING LABORATORY 105 less Black Valentine pods from the first harvest when grown at Belle Glade. The pods do, however, tend to curve more after the first harvest or during hot weather. The color index is con sidered medium for both varieties. Con tender develops some purple splashing of the pods when grown on very in fertile soils, the amount being negligi ble under desirable growing conditions. The pods of this variety are stringless and the total fiber content is significant ly lower than that of Stringless Black Valentine. The seeds are buff with a slight mottling of brown and they aver age approximately 70 per ounce. Con tender is resistant to common bea.1 mosaic and has considerable resistance to powdery mildew. Yields have been consistently higher than those for Black Valentine. Our breeding work with snap beans is now being done by J. C. Hoffman of our staff, who was formerly horticulturist at the Everglades Station. Trials of breeding lines are being continued at several locations in Florida as well as in other Southern States. W. A. Hills of the Everglades Station has recently selected two new lines from such ma terial. They combine resistance to dis ease with high quality. Both will prob ably be entered in the 1951 Southern Snap Bean Cooperative Trials, of which Hoffman is the chairman. Interest in frozen beans is on the in crease in Florida. Mr. Gray Singleton, Southland Frozen Foods, Inc., Plant City, Florida, has tested a large number of our breeding lines. This work is also in cooperation with the Agricultural Experiment Station. Cooperation with commercial concerns has been found to be very effective, since they supply freezing facilities and help evaluate our more advanced breeding lines for pro cessing. A new selection of B1515 may have some very valuable commercial possibilities as a freezing and shipping type. Seed of this is being increased with a view to introduction. In addition to the processing tests, many commercial growers have been very cooperative in comparing these new breeding lines with standard varie ties. These commercial tests are con sidered of the greatest importance in evaluating advanced breeding lines, and without this help from growers we could accomplish little. Our breeding work with English peas is, in a sense, pioneering, since there is now no large, well established pea in dustry in the South. This is a cool weather crop, yet it lacks adaptability to long periods of cold weather and has a narrower range of optimum growing conditions than cabbage, for example. In its early life it can be quite hardy, yet when it comes into flower it loses its hardiness to cold while exhibiting a distressing dislike for hot weather. Southern winters being what they are, our English pea breeder, J. A. Eades, who is also chairman of the Southern Cooperative Pea Trials, faces a prob lem of considerable dimensions. He has had a good deal of success in develop ing dwarf to semi-dwarf lines with a high degree of cold hardiness through the first eight nodes and that yield much better under adverse conditions than established varieties like Alaska, Progress, Thomas Laxton, and Little Marvel. Hardiness has been obtained from the cold resistant Willetts Wonder and Austrian Winter and high quality from the standard market garden varie ties, such as Progress. Cold tests car ried on in the field during the winter are supplemented by the artificial freezing of young plants in a liquid that freezes at a temperature much lower than that at which water freezes. It has been observed that practically all varieties of peas are hardy for the first three nodes and that this early hardiness is lost when the plants come

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106 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 into bloom. The earliest varieties, which bloom early, thus soon lose their resistance to cold. One trick in breed ing for hardiness, then, is to select plants that bloom a little later, yet maintain this resistance to cold until they come into bloom. Some tolerance to heat has also been observed and in corporated in the hardy lines. Wando, a variety introduced by the Vegetable Breeding Laboratory, combines a con siderable degree of resistance to both heat and cold. So do two advanced breeding lines, Pl 7 and P84. Both of these are in the Southern Cooperative Pea Trials. These have been grown by R. W. Ruprecht at the Central Florida Experiment Station at Sanford and by F. S. Jamison at Gainesville. These trials have turned up two varieties for freezing that look promising-Dark Skinned Perfection and Victory Freezer. The development of fully satisfactory market garden and processing types of English peas would be a boon to Florida growers by providing a cash crop at a relatively slack season. The tomato breeding program at the Regional Vegetable Breeding Labora tory has been conducted since 1945 by C. F. Andrus, who has developed the pattern of the Southern Cooperative Vegetable Trials in his capacity as chairman of the tomato variety tests. Disease resistance has been, and still is, the keynote of the tomato breeding efforts. Most breeders agree that re sistance to fusarium wilt should be a requirement for every variety for which a wide distribution is anticipated. Other diseases for which resistance is now available in breeding lines include alternaria, anthracnose, bacterial wilt, collar rot, early blight, late blight, leaf mold, mosaic, rootknot, septoria, south ern blight, spotted wilt, and stemphy lium. It should be pointed out that a number of these breeding stocks are lacking in size of fruit or other horticultural characteristics. Considerable progress has been made toward com bining resistance to several diseases in a single stock, usually a combination of resistance to fusarium wilt and to two or three other diseases. More work is being done on the breed ing of tomatoes than of any other single vegetable crop in the South. This is reflected in the larger number of breed ing lines-no less than 160 observed thus far in the cooperative trials. As with other crops, the Laboratory sends to State men breeding lines of tomatoes as sources of disease resistance or other desirable characters. During the past three years 107 packets of seed of toma to breeding stocks have been sent to Station workers in Florida alone. The Laboratory has two new breed ing lines, grown in the cooperative trials under the numbers STEP 68 and STEP 89 in which Florida growers have shown considerable interest. Both of these lines rank high in the STEP trials, which indicates, among other things, a wide adaptability to diverse growing conditions, and can mean consistency in production over a period of years. STEP 68 has large red oblate fruits that mature as early as Grothen's Globe. In addition it is resistant both to fusarium wilt and to alternaria leaf spot. STEP 89 is the most productive tomato in the cooperative trials, and equals Rutgers in size, earliness and appearance. It is also resistant to fusarium wilt. It is anticipated that tests of these two varieties in Florida will total over a hundred acres this season. The development of the Congo water melon is another example of the value of cumulative contributions by many interested workers. Congo's value to the industry lies in its combination of four highly desirable characters, viz, fruit size, dessert quality, shipping quality, and resistance to anthracnose. The anthracnose resistance was found

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YAH.NELL: VEGETABLE BH.EEDING LABOH.ATORY 107 in a watermelon brought to this coun try from Africa by a missionary. Crosses were made with that melon as one parent at the Iowa Experiment Sta tion. This material was selected at Leesburg, and also at the Regional Vegetable Breeding Laboratory by C. F. Poole, who is now breeding vegetables in Hawaii, and by C. F. Andrus, who has continued the breeding of water melons at the Laboratory. A selection was crossed with Garrison and seed lings were saved on the basis of four characters mentioned. The "coopera tion" thus far was more or less hap hazard, but from this point on the tests in growers' fields and the esti mates of shipping quality were the re sult of the interest of many people working together towards a definite goal. Among these were State and Federal research men, State extension workers, railroad agricultural agents, seedsmen, and growers in Florida and northward along the coast to the Caro linas. The Leesburg and Charleston labora tories have worked together very close ly for the past 12 years. This has included a generous exchange of breed ing materials =which have been used at both locations. One result of this co operation is the wilt resistant Ironsides watermelon, which is about ready for release by the Florida station and the Department. My own breeding work is with cab bage and sweet corn. Breeding tech niques for cabbage have received a good deal of attention. These include methods of storage, the flowering of plants from the spring crop under con trolled conditions, with and without flower-stimulating chemicals, and arti ficial tests for resistance to cold in the seedlings. Numerous crosses have been made between well adapted breeding lines and yellows-resistant varieties of high quality. These are being selected for desirable combinations in the fall crop. Considerable resistance to the corn ear worm is being obtained in adapted sweet corn inbreds. This appears to be of two types-physical structure and some chemical constituent that is un attractive to the insect. After careful consideration of the evidence I have come to the conclusion, in spite of live ly discussions between proponents of the two theories, that the two are not mutually exclusive, but that a long, tight husk may supplement the more subtle chemical resistance in reducing damage from this insect. Another important problem of sweet corn growers in the South is the main tenance of sugar content of market corn shipped to the North. Both the original sugar content and the rate of loss at various temperatures are con cerned. This is perhaps a good place to introduce the work of our chemist, Margaret Kanapaux. Numerous samples of both varieties and breeding lines of sweet corn have been analyzed for sugar content just after harvest and after storage at room temperature and at 45 F. Varietal differences have been found for both reducing and total sugars as well as differences in sugar retention at both temperatures. The work thus far indicates the possibility of increasing both sugar content and sugar retention in sweet corn through selection. A great variety of chemical tests are made each year in support of the breed ing program. These include many as says of the ascorbic acid content of snapbeans and cabbage, and especially of tomatoes. The thiamin content of English peas is under investigation. Fibre content and the color values of pods of snap beans are other charac teristics that are accurately determined in the laboratory. Nutritive values are among those things that are affected

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108 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 by both hereditary factors and growing conditions. While the slogan "Eat this because it is good for you" is not one that is calculated to guarantee the ac ceptance of a new variety, it is some thing that is important to the general health and as such is the proper concern of the plant breeder. In this discussion of the breeding and testing of l).eW vegetable varieties I have emphasized cooperation amo1_1g those engaged in this work as one of the essential "facts of life." I favor co operation not just because it might be a popul a r movement, but because it helps get results. Biological research is at least as complex as research in engineering and in the sciences of physics and chemistry. It is a consid erable source of satisfaction that vegetable men in the South interested in the development of new varieties are finding a mutual advantage in the ex change of information and materials of aid in their research and that these are being handed on . to the growers of Florida and other southern States as increased help in solving their common problem s . NEW VEGETABLE VARIETIES FOR FLORIDA DAVID G. A. KELBERT Florida Agricultural E xperim ent Stations Vegetable Crops Laboratory Bradenton Since 1944 the last information on vegetable varieties for the State of Flor ida was compiled, hundreds of new varieties and lines of vegetables have been tested and evaluated by experiment station workers in all vegetable growing areas in the State. Much of the infor mation in this paper has been contributed by these investigators. Plant breeders have placed much em phasis on resistance to plant diseases in the breeding of vegetables. The number of new varieties which have resistance to one or more serious diseases testifies to the great strides that have been made along this line. Resistance to diseast (and in some instances to insects) is highly important. In fact in some areas it is absolutely necessary where soils have become so contaminated with de structive diseases that the growing of susceptible crops is no longer profitable. Rotation of crops on these lands tends to reduce the severity of infection on the next susceptible crop, but proves of little value if conditions are optimum for the development of disease. At present the only practical answer to the problem of infested soils is through resistant types. Many modern vegetable varieties are not only resistant to soil-borne disease such as fusarium wilt, bacterial wilt, po tato scab, etc., but also extremely resistant to diseases which cause leaf and fruit spots such as early blight, late blight, grey leaf spot, and so forth. One of the new cantaloupe varieties is even consid ered resistant to attack by aphids as well as the powdery mildew. 'J:he breeding of these characters into vegetables has re quired years of diligent work by the men responsible for the great advances that have been made. There are still many problems to be solved. Unfortunately many of the new varieties, especially those resistant to certain diseases, seem to be adaptable to a very limited area and environment. This seems to be especial ly true of tomatoes. Many new tomato varieties that seem to have nearly every desirable character such as multiple re sistance to diseases, excellent quality and high yield capacity in the area of their conception, fail miserably in another area, often only a few miles away with

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KELBERT: NEW VEGETABLE VARIETIES 109 cultural practices and other environ mental factors apparently identical with its home area. This fact is extremely discouraging but is a problem that must be solved. In order for a new variety to gain favor with seed producers and distributors, it must be adaptable to a fairly wide area and range of conditions. It would, of course, be impractical for seedsmen to handle a different line or variety for each locality. This lack of general adaptability is reflected in the large number of recom mended varieties in the following group of vegetables. Beans :-Several new varieties of bush beans have proven superior to Tender green and Black Valentine. The most outstanding beans of the group are Con tender, Top Crop and an unnamed variety No. 1515. All three of these are resist ant to powdery mildew and mosaic. Con tender and Top Crop have been outstand ing in recent trials at Belle Glade, Home stead and Gainesville. No. 1515 is evi dently adapted to a wide variety of soils and conditions as it has been grown successfully on sandy soils, the Gulf Coast, Gainesville and Plant City areas and the organic soils of the Everglades and the marl soils at Homestead . Al though pod shape and yield capacity of these new varieties have proven satisfac tory in tests, several workers have men tioned the fact that they show the unde sirable characteristic of producing numbers of pods in contact with soil; but none have discarded the variety because of this fault. Cherokee Wax is still considered the best shipping variety of this type of bean. There has been little progress in the development of new pole bean varieties. No. 191 and McCaslan have been superior to all others tested. The following new introductions have been tested at Gaines ville and several other stations: Can freeze, Green Savage and Alabama No. 1 Green Pod. All are prolific but lack the right pod characters to compete with the No. 191 type. English Peas :-Dark Skin Perfection is being recommended in the Sanford area. Southern Peas (Edible Field Peas): This has been a sadly neglected crop and few references are found to desired varieties that can be grown except for use as cover crops. Many people do not realize that there are several varieties delectable to the palate when properly prepared. The most widely known variety is the Black Eyed Pea, but there are others which to the writer's taste are far superior. Those recommended for trial are Wood's Sumptious, Purple Hull, Brown Crowder, Blue Goose, Virginia Blackeye and Alabama Crowder. Cabbage :-Markets for Florida cab bage show a decided preference for the small solid head type, such as the variety Copenhagen Market. The new variety Bonanza has been recommended as an outstanding variety for compactness, solidity and small core on organic so _ ils, but is considered too late for the Home stead section. The soil-borne disease Cabbage Yellows, is becoming more widespread through out the state, hence varieties resistant to this disease are becoming more import ant. Soils once infested retain the disease and susceptible varieties should be avoided. The following yellows-resistant varieties are available for planting on diseased soils: Resistant Detroit (Early), Marion Market, Resistant Copenhagen Market( medium early) and Resistant Glory of Enkhuizen. Cauliflower: Holland Erfurt and Snowball X or Snowdrift are the varieties most commonly grown. A new variety Snowball Y is recommended for trial. Though several days later than the above, its upright non-spreading type of foliage protects curds until nearly grown. It is recommended for limited trials. Broccol-i:-Three new varieties are

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110 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 recommended for trial when seed becomes available: Freezers, Midway and Texas 107. Texas 107 produced almost double the yield of others in trials. A light yellow tinge on buds is objectionable. Lettuce:-Great Lakes and Imperial 44 are still the standard varieties. Cucumbers :-Marketer (Early Green Market) is a widely adaptable variety and is considered the standard by grow ers and buyers in most sections. A new South Carolina variety named "Santee" has yield capacity superior to Marketer and fruits of good color with a slight flecking which is not serious. This line is not as resistant to downy mildew as Palmetto; both have a tendency 'to form hollow spaces inside of fruit. R ec ommendations :-Marketer (Early Green Market) Santee for limited trial; and Palmetto for planting when spraying and dusting equipment is inadequate and control of downy mildew is a problem. Eggplant:-Two new varieties, Flor ida Market and Florida Beauty recently introduced by the Florida Experiment Station, are resistant to all phases of the disease known as Phomopsis or Tipover. Though still segregating for fruit color and type these varieties are recommended for all eggplant-growing sections. Flor ida Market seems to be preferred where it has been tried . Yield capacities of these varieties in commercial plantings have been excellent. Onions :-Interest in onions is being revived as a result of availability of dry ing equipment which might be used in the curing of onions. Two varieties which have performed well under most Florida conditions are Early Grano and Excell. Tomatoes :-This is probably the most important vegetable crop grown in Flor ida and is second only to bush beans in acreage. Rutgers, Stokesdale and Grothen's Globe are the varieties com monly grown with about 75 percent of the acreage in the lower half of the state planted to Grothen's Globe, both in the fall and spring. Markets show a marked preference for globe-shape fruit and object to roughness and large blossom scars. Several new varieties tested in recent years appear to be better than Grothen's Globe and Rutgers from the standpoint of yield and marketability but they do not seem to be entirely satisfac tory and their general adoption to replace present standard varieties appears doubt ful. Tomatoes are susceptible to numer ous plant diseases, the most destructive of which are Fusarium wilt, mosaic, late blight and bacterial wilt. Fusarium wilt is prevalent in all areas of the State. It is especially destructive on sandy lands but is now becoming prevalent on the marl land on the lower East Coast. Most of the new tomato introductions are resistant to one or more of these dis eases. As stated above, widespread trials indicate that the adaptation of these new varieties has been confined to rather limited areas. Commercial seed stocks are available of some of them. The varieties Manahill and Manasota seem to do fairly well in the southern section of the State and along the Gulf Coast. Manahill has a tendency to pro duce rough fruit with large blossom-end scars under some conditions but it is of excellent quality and flavor. It is resist ant to fusarium wilt, alternaria (early blight) and gray leaf spot. Manasota, considered best for fall growing, is quite susceptible to blossom-end rot and gray leaf-spot, but is resistant to Fusarium wilt and produces globe shaped fruit that average small in size. Both of these varieties consistently produce higher yields of marketable fruit than Rutgers and Grothen's Globe. Jefferson, resistant to Fusarium wilt, has proven very satisfactory in some plantings on the Gulf Coast and at Gainesville. Reports from Gainesville indicate better than average yields of No. 1 fruits, resistance to cracking and about

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KELBERT: NEW VEGETABLE VARIETIES 111 the same maturity date as Rutgers. Ex perience with the variety in the Ruskin Manatee section has been varied, indi cating that it is sensitive to environ mental factors of soil and cultural prac tices. Limited trial of this variety is recommended. Wilt resistant Grothen's Globe, intro duced in 1948, has been grown with varied results at Bradenton and Ruskin. It is somewhat later in maturity than regular Grothen's Globe. First cluster fruit have a tendency to be rough, but yields of No. 1 and marketable fruit have been superior to regular Grothen's. Several other new unnamed varieties show considerable promise, but most of them po;;sess more or less objectionable defects. Perhaps the most promising of these varieties is one of the Southern Tomato Exchange Program (STEP ) lines carry ing the number STEP 89. This variety is of Rutgers type, with good skin tex ture and quality and ripens evenly at the shoulders. It is resistant to Fusarium wilt and has a vigorous vine. It has per formed equally well as a ground tomato or staked and pruned. Reports from different sections of the State indicate that it is adapted to a rather wide range of conditions . Other numbered varieties that look promising are STEP 135, STEP 68, and Missouri S34. All of these have produced better yields than Rutger s or Grothen's Globe, but are not entirely satisfactory due to irregular shoulders, large blossom scars, uneven ripening or other defects. Continued selecting may eliminate these faults and one of these may become the ideal tomato we have been searching for. Sweet Corn:-Interest in this crop has resulted in expanded acreage in nearly every section of the State. Since the advent of DDT and other new insecticides used for the control of ear worms, the acreage of sweet corn planted in the State has increased to more than 27,000 acres. The major share of the crop is planted to two varieties, Joana and Golden Cross Bantam. Golden Security is gaining in favor, while Calumet and Gold Rush are planted extensively in the Glades area. Erie and Calumet are being recommended for the sandy lands around Sanford. Illinois Golden No. 10 pro duced well in most areas. All things considered hybrid sweet corn has been a successful crop wherever it has been tried but new growing and handling problems complicate the production of the crop. As the acreage expands and large areas are given over to corn, insect control becomes more difficult and dis eases become more prevalent and de structive. During the season just past, corn ear worms and army worms were so numerous that it was almost impos sible to control them with methods which had been successful heretofore . Hel minthosporium leaf blight has become so prevalent that it was directly responsible for the total loss of some plantings attacked in the early stages of growth. Increased production and ample supply throughout most of the season reduced competition for the crop and buyers be came quality conscious. Wormy and otherwise poor corn became a drug on the market and heavy losses were sus tained by many growers. As acreage increases and the consumer becomes accustomed to fresh sweet corn out of season growers are going to find it necessary to plant varieties having better quality than the present varieties. There are a number of these available at the present time, and new ones will be found that will be superior. As stated above, . there are numerous varieties suitable for growing in all sec tions of Florida. Generally speaking , the varieties that produce wen in the spring can be depended upon to produce good corn in the fall under reasonable weather conditions. New, , varieties rec' ommended for trial include.Erie, Aristo

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112 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 gold Bantam Evergreen, Parade, Huron, Flagship, KVF 45-10, Double Duty. For white hybrids, try Silverliner or Truck ers Hybrid. For large ears, Golden Grain is recommended. Celery :-A new variety being recom mended for trial in the celery growing sections is Emerson Pascal. Recently released and tested, it has high resistance to celery blight. Potatoes :-Kennebec, a promising new white-skinned variety, has yielded about the same as the standard Sebago in tests at Hastings during the last four years. Its tubers are similar to those of Sebago in color, size and shape and earliness. It is moderately resistant to cracking; its resistance to brown rot is unknown. Kennebec is highly resistant to late blight. It is recommended for trial by growers. Dakota Chief is recommended for the Sanford area. Cantaloupe :-Acreage of this crop is on the increase in the State. With the introduction of new fungicides capable of controlling downy mildew, the most destructive disease, and insecticides that are almost specific against the pickle worm and aphids, a number of varieties have been grown successfully commer cially along the Gulf Coast. There are commercial varieties that fill the needs of most demands for .fruit size and quality. Of these the following are recommended: Powdery Mildew Resistant No. 45 and No. 5 produce medium size, well netted fruit; Hales Best and Hales Jumbo, medium and large fruit also well netted; Burrell Jumbo (a strain of Hales) and Smiths Perfect, a downy mildew resistant variety of delicious quality for local consumption. It will not stand shipping and rough handling. Two large muskmelons, Seneca Bender and Schoons Hardshell are recommended for trial. The latter is very resistant to worms; both have excellent quality. Several new varieties almm,t immune to downy mildew were grown at the Vegetable Crops Laboratory last spring. These originated in Texas and Georgia and showed much promise. They pro duce heavily netted, medium sized fruit and have quality equal to Smith's Perfect. When seed of one or more of these varieties become available, it is possible that acreage of this crop will expand rapidly. EFFECT OF LOW NITRATE NITROGEN ON GROWTH OF POTATOES GAYLORD M. VOLK AND NATHAN GAMMON, JR. Florida Agricultural Experiment Station Gainesville A type of leaf roll occurring on Irish potatoes growing on acid flatwoods soils was brought to attention in March of 1949. Leaf margins were rolled up ward and in toward the midrib. Stems and the under surfaces of leaves some times had a purple tint, but there was no leaf pattern of yellow or faded areas so commonly associated with a deficiency of some element. The trouble appeared mainly on Leon and similar soils of the Federal Point and Bimini areas. Later it was also found in the LaCrosse area. The first symptoms appeared soon after the first thin leaves were formed, but usually became the most pro nounced about blossom time. The leaf roll was permanent once it had taken place. It was also noted in subsequent examination of plants showing the symptom that tubers were set so close to the stem that movement of them

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VOLK AND GAMMON: NITROGEN FOR POTATOES 113 would be necessary . for normal enlarge ment. This condition is commonly noted on potatoes that have been retarded for some reason, but in this case might have special significance in that it was pres ent even when the above ground portion of the plant was normal in size and general appearance with the exception that the leaves were rolled. No indication of a disease organism was found in connection with the roll ing. Analysis of several soil samples collected from the various fields in the Federal Point and Bimini areas where the rolling was severe, showed that the soils were very acid and exceptionally high in ammonia nitrogen as compared to more normal portions of the same fields. This indicated that the bacterial activity necessary to convert ammonia nitrogen over to nitrate nitrogen might be inhibited. Incubation tests carried out in the laboratory did show this to be the case. With this lead, field tests were made in cooperation with the Hastings Potato Investigations Labora tory in which fertilizers carrying dif ferent ratios of nitrate to non-nitrate nitrogen were used in combination with various lime treatments. Bimini Tests Twenty-five hundred pounds of the various fertilizers were used per acre in the drill or split application. All materials were made physiologically neutral with dolomite except in treat ment No. 4 where extra dolomite was added. Running across the rows were bands of lime and Cy a namid singly and and in combination. Lime was used at one-half and one ton rates and Cyana mid at 240 pounds. Average yields for certain treatments in the 1950 test are as follows: 1950 BIMINI TESTS No, 2 5 . 8 4 1 5-6-6 Tr tntment 2500 Lhs. per Acre 2.0 units from nitrate Same mixture as above, only 3/5 at planting and 2 / 5 side at 60 days 5-6-6 No nitrate All at planting Same as above plus 300 lbs. extra dolomite above neutral in fertilizer Grower's 6-8-8 .75 units from nitrate All at planting :rfo L i me or Cyanamid 1949 Area of Curl e d Leav es N o t Curl e d in 1949 pH 4.2 to 4 . 4 pH 4.7 to 4.9 Av . Yi e ld, 4 Plot s I 241 bu. (Normal leaves in 1950) 241 bu. (Normal leaves in 1950) 165 bu. (Rolled leaves in l!l50) 183 bu. (Rolled leaves in 1950) 201 bu. :, .... Av . Yi e ld , 4 Plot s II 292 bu. 331 bu. 313 bu. 308 bu. 312 bu .

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114 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 From column I it will be noted that in the area where leaves were badly rolled in 1949, nitrate nitrogen in the fertilizer (No. 2) eliminated the symp tom in 1950 and produced 46 percent greater yield than No. 3 . Three hun dred pounds of dolomite per ton above that needed to neutralize the high am monia fertilizer (No. 4) improved the yield by 11 percent over No. 3 but did not eliminate the rolling of leaves. The second column shows that at the higher soil . pH where rolling was not severe in 1949, low nitrate fertilizer produced good yields. It should be noted that the split application of goods carrying 2.0 units of nitrate nitrogen (No. 5) produced the best yield. This indicates that leaching of nitrates prob ably took place to lower the yield with the . No. 2 treatment. The greater the amount of nitrate nitrogen used in a fertilizer, the greater is possible need for side dressing with nitrogen later on if heavy rains occur. This fact, along with a reluctance to side dress, may partially account for the swing to lower nitrate and higher ammonia nitro gen in recent years. The latter does not leach readily. The test with 300 pounds of extra dolomite in the fertilizer was made to test the effect of reducing acidity in the fertilizer band. Apparently there was some benefit and it was planned that further work be done along this line. However, Dunton, Bell and Taylor (1) have since reported on the effect of dolomite in the fertilizer band and have shown that the acidity migrates away from the band before the lime can react effectively to neutralize it. Soil pH dropped from 5.7 down to 4.4 two inches above the band even when 300 pounds of dolomite above that necessary to neutralize the fertilizer was used. The pH of the band did rise to approxi mately 6.2 temporarily but then dropped to 5.5 in two months. The increase noted in treatment No. 4 probably is the response to the effect of this temporary rise in pH on local nitrification. Neither lime nor Cyanamid appeared to increase the yield by more than five percent where the soil pH was 4.7 to 4.9. Where the soil pH was 4.3 to 4.5, lime still did not improve yield but Cyanamid increased the yield by about 25 percent. The lime was applied in November and according to soil pH did not have time to react. Cyanamid probably helped by supplying a nucleus of quick acting lime hydrate and nitro gen together, so that nitrification was improved at the vicinity of each granule of material. Hastings Tests These plots were intentionally laid out on an area containing a spot of very light sandy soil. Yields were low and _ erratic. Treatment No. 2 containing nitrate nitrogen gave about 25 percent greater yield than No. 3, the low nitrate treatment. The main contribution from this test was the demonstration that rolling was not present on the bette1 soils even in the absence of nitrates in the fertilizer, but that it did occur in the lighter sands with the high am monia fertilizer. There was no response to dolomite either in yield or pH change, therefore it was assumed that the lime did not have time for proper reaction because of time of application and the dry season. Additional tests in which the per acre treatments with No. 3 and No. 4 materials were lowered did not reduce the rolling. From this it is asirnmed that the response was due to addition of nitrate nitrogen rather than possible reduction of toxicity of ammonia. Analysis of plant tissue for ammonia and nitrate nitrogen showed that the rolling was progressively less where the nitrate nitrogen content of the tis

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VOLK AND GAMMON: NITROGEN FOH POTATOES 115 sue increased, but there was no correla tion with ammonia. There was no correlation with the amounts of cal cium, magnesium, potassium, phos phorus, sodium or iron in the tissue on a limited number of samples tested. One test on new land showed excel lent response to nitrate nitrogen and to lime as compared to ammonia nitro gen, both in marked increase in yield and elimination of rolling of leaves. Examination of soils for accumula tion of soluble salts, chlorides espe cially, did not show this to be a factor in the problem. Conclusions Analysis of soils, plant tissue and yield data are quite conclusive in indi cating that low nitrate supply to the potato plant is the cause of the rolled leaves. The amount of ammonia nitro gen is apparently not a factor except as it may produce a larger plant in which the symptoms of nitrate defici ency are more pronounced when a stress period, probably of moisture supply, sets in. Normally fertile soils of the areas in question will nitrify ammonia fast enough to supply nitrates from ammonia in an average year. The more acid the soil, the greater the possibility of poor nitrification. On a very dry year more soils would fall in the group not having adequate nitrate producing ability. Apparently the trouble is character istic of very sandy soils and certain very acid soils; the first because leach ing of nitrate and even ammonia nitro gen is rapid, and the second because nitrification is very slow at low pH. Just where the critical pH lies is not definitely known, but liming when the pH is 5.0 or below should be in order. This is in agreement with findings re ported by Odland and Allbritten (2) that a soil reaction between 5.0 and 5.5 seems advisable in order to obtain the best yields of potatoes with the least scab. Soil samples taken in October and early November at a time when the soil is not wet are the most reliable for pH determination. Lime hydrate should be used for quick action but agricul tural limestone, either calcic or dolo mitic, is satisfactory if applied in early summer. Five hundred pounds of hydrated lime or 1000 pounds of agricultural limestone are adequate at one time. A recheck of pH will determine if the treatment needs repeating the next year. The possibil ity of a year of poor nitrification is such that fertilizer should carry at least one unit of nitrate nitrogen. For those areas where rolling has been prevalent and pH is below 5.0, it is sug gested that in addition to recommended liming, one-third of the nitrogen be from nitrate sources. The grower must be prepared to side dress with a nitrate carrier if heavy rains occiir. LITERATURE CITED 1. DUNTON, E. M .. Jn., BELL, F. W., and TAYLOI\, M. E. The influence of acid-forming and neutralized fertilizer on the soil reaction and nutrient level in the Irish potato row during the growing season. Agron . ]. 42: 512-515. 1950. 2. 0DLAND. T. E., and ALLBRITTEN, H. G, Soil reaction and calcium supply as factors influ encing the yield of potatoes and the occurrence of scab. Agron. ]. 42: 269-275. 1950.

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llG FLORIDA STATE HOHTICULTUHAL SOCIETY, 1950 EFFECTS OF SOLUBLE SOIL SALTS ON VEGETABLE PRODUCTION AT SANFORD PHILIP J. WESTGATE Florida Agricultural Experiment Stations Central Florida Experiment Station Sanford In a humid region of sandy soils, such as is found in the vicinity . of San ford, soluble soil salts are derived pri marily from fertilizer and artesian well water residues. In the production of winter vegeta bles, principally celery in the area, large amounts of commercial fertilizer are applied during the relatively dry winter growing season. It is not un usual for growers to apply from two to four tons of commercial fertilizer per acre to celery. In addition, two to four tons of soluble salts, over half of which are sodium chloride, may be added by each acre foot of artesian well water used for sub-irrigation through tile placed above a hardpan. Such large amounts of fertilizer and well water salts, if not washed out by frequent rains, may build up concentrations of soluble salts detrimental to plant growth. The following three fields in the Winter Garden vegetable area will illustrate what excessive fertilizer buildup alone will do to vegetable pro duction. The sampling date was May 9, 1950. Field No. 1 was planted to, and pro duced one excellent crop of cucumbers each calendar year. Field No. 2 was planted to three crops, one of peppers and two of cucumbers, in one year, in cluding a full fertilizer program for each crop, with successively poorer re sults. Fertilizer residues were the principal source of soluble soil salts in both fields since the irrigation water iri both cases was very low in total dis solved salts i.e. less than 100. parts per million of Chlorides (Cl.) 2 A virgin sand area east of Sanford near Lake Harney showed no plant growth, not even weeds or grasses. An analysis of this soil without the addi tion of fertilizer showed a total soluble salts reading of over 1000 MHOS x 10-5, the upper limit of the scale, 9000 p . p.m. of Chlorides (Cl.), and 5700 p.p.m of sodium (Na.) This would amount to over twelve tons of sodium chloride per acre in six inches of soil. 1 Throughout thi s paper "Total Soluble Salts" is given as the Specific Conductance expressed as MHOS X 10-• at 25• C. as determined on a Solubridg e , using a solution of one volume of soil plus two volumes of wat e r. The higher the soluble salt s . the higher the reading obtain e d. Chlorides w e re d e t e rmined by titration with silv e r nitrate and expr e ss e d a s parts per million of chlorine ( p.p . rn. Cl.) in the w a t e r or soil samples. pH det e rminations were made using a Quinhydron c electrode with on e volume of soil plus two volumes of distilled water. Total Soluble . Salts Specific Conduct a nce MHOS x 10-' 1 1 111'., Soil Depth Soil Profil e Virgin Soil Fi e ld No. 1 Field No. 2 (No Crop) (Good Crop) ( Poor Crops ) 0-1" Sand 0 55. 340. 0-6" Sand 0 60. 130. 6-12" Sand 0 23. 28. 12-18" Sand 0 22. 15. 18-24" Hardpan 0 10. 0.

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WESTGATE: SOLUBLE SALTS 117 The pH of this soil was 5.90 3 Evapora tion of saline underground waters prob ably accounted for the accumulation of soluble salts in this spot. An adjoining corn field in the Lake Harney area showed uneven growth of corn. The poor spots in the corn showed stunting, "firing" of the lower leaves, and a chlorosis or yellowing of the plant as a whole. The surface soil from good and poor areas in this corn field analyzed as follows : Total Soluble Soil 0-6" Chlorides Salts pH (p . p.m. CI) (?.!HOS x 10-") "Good com" HPoor corn" 133 . 466. 30. 90. 5.88 5.87 The irrigation water for this corn field was pumped from Lake Harney, which showed a chlorine content of 541. p.p.m. CL The adjoining artesian well, approximately 125 feet deep with 8200. Water Sample Remarks (1) Lake Harney water (used for irrigation) (2) Lake Harney water after washing out good corn soil. Good peas (3) Lake Harney water after washing out poor corn soil. Grew good peas only after washing p.p.m. Cl. was capped and not used for irrigation because of the high salt con tent. In pot tests, soil from the poor spots in the corn field grew good cowpeas after leaching with Lake Harney water, but not before. The following data was obtained from the leachates. The two previous examples have illustrated troubles due to soluble soil salts, first from fertilizer at Winter Garden, and second from saline waters at Lake Harney. In the Sanford vegeta ble area we are confronted with both a wide range in salt content of artesian well waters used for irrigation, and a wide variation in the amounts of soluble commercial fertilizer used. Underlying these soils are hardpans of varying per meabilities at different depths from the surface. The following well water samples analyzed in 1950 will illustrate the wide range in salt concentration of various wells in the Sanford area. The question arises as to whether or Chlorid es (p.p.m. Cl) 541. 640. 4969. Total Soluble Salts ( Ml!OS X IO-•) 200. 260. 1000. pH 6.86 6.52 7.00

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118 FLORIDA STATE HORTICULTURAL SOCIETY, Hl50 No. of Chlorides (p.p.m. Cl) Well Location Remarks Wells Low High Average Tested Well Well Samsula Shallow, Pumped 2 33 49 41 Zellwood Shallow, Pumped 1 49 49 49 Winter Garden Shallow, Pumped 2 33 66 49 West Sanford Free flowing, artesian 2 82 98 95 South Sanford Shallow, Pumped 1 96 96 96 West Sanford Free flowing, artesian 9 91 733 435 East Sanford Free flowing, artesian 4 525 558 533 East Sanford Free flowing, artesian 8 525 623 549 S.E. Sanfo1d Free flowing, artesian 3 476 607 557 Oviedo ' : Free flowing, artesian 7 286 1098 595 East Sanford Free flowing, artesian 4 590 607 603 East Sanford Free flowing, artesian 24 333 932 613 S.E. Sanford Free flowing, artesian 4 893 1140 977 West Sanford Free flowin g, artesian 2 1098 1115 1106 S.E. Sanford Free flowing, artesian 1 1132 1132 1132 Oviedo Free flowing, artesian 6 869 1509 1255 Iowa City Free flowing, artesian 1 1714 1714 1714 Lake Harney Free flowing, artesian 1 8200 8200 8200 not the salt content of the artesian wells in the Sanford area changes from season to season or from year to year. The following wells in this area have been analyzed for chlorides during the past fifteen years with these results: Location Depth (Ft.) West Sanford 151 East Sanford East Sanford 227 West Sanford 157 Lake . Harney 125 Thus of the artesian wells tested fif teen years ago by the Central Florida Experiment Station, and retested in 1950, the only one which had any sig nificant increase in chloride content was one which had been deepened in the Chloride Content _ (p.p.m. Cl) 1935 1936 1938 1941 1950 35 50 Deepened 500 452 466 565 503 525 1225 1040 1188 1115 8900 (Capped) 8200 intervening years because of loss in head. The other wells, of a wide range in salt concentrations, remained prac tically constant whenever checked dur ing the fifteen year period. Geologists tell us that these artesian wells are

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WESTGATE: SOLUBLE SALTS 119 merely washing out the salts in the layers of rocks laid down when central Florida was under the sea (2). As the suggestion has been made that surface water might be substituted for our artesian well water as a source of irrigation water, several sources of sur face waters were analyzed as follows: Date Water Sampled 3/24/50 5/24/50 3/20/50 5/19/50 3/27/50 6/12/50 12/14/35 1939 3/15/50 3/19/50 Location Elder Spring water, south of Sanford (analysis on label) Rock Springs (flows into Wekiva River) Black Lake, Winter Garden (citrus irrigation) Buck Lake, Geneva Lake Jessup Wekiva River (near St. John's River) Lake Harney Lake Harney Lake Harney Lake Monroe (16 samples, east and west, surface and bottom, maximum depth 12 feet) Minimum sample Maximum sample Average for the day 1926-1950' Lake Monroe 5/2/50 5/16/50 5/27/50 11/3/50 3/24/50 Minimum Maximum St. John's River (Osteen Bridge) St. John's River (Osteen Bridge) St. John's River (Osteen Bridge) (Water very shallow at this date) St. John's River (Osteen Bridge) (Water very high at this date) Atlantic Ocean (East Coast, Canaveral) Chlorides {p.p.m. Cl) 8. 16. 66. 66. 71. 164. 150. 1030. 315. 300. 333. 316. 62. 937. 377. 459. 820. 98. 21,520. Thus there is a wide variation and fluctuation in the chloride content of surface waters in the Sanford area. Th . ese sources, such as the St. John's River, Lake Monroe, and Lake Harney, vary with the season of the year, de pending upon the rainfall and evapora tion. water is the fact that when irrigation water is not required the chloride con tent of the river water is low, but when irrigation water is most needed, the chloride content of the river water is even higher than most of the artesian wells in the area. One disadvantage of the St. John's River as a possible source of irrigation The fresh water springs, fresh water lakes, the Wekiva River, shallow pumped wells, and our fifty inches of

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120 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 rainfall per year are all potential sourc . es of water low in chlorides. On February 7, 1950, during an un usually warm, dry winter season, the Depth of Soil Sample Remarks 0-1" White sand crust following soil profile was analyzed from a poor spot of celery in an old tiled field along Celery Avenue, Sanford. These poor spots in old celery fields Total Soluble Salts (MHOS X l') pH 155. 5.65 4-8" River "muck" and 2-year-old, undecomposed corn stalks 85. 5.48 8-12" Dark Sand 38. 6.52 16-20" White sand 33. 7.00 TILE (For irrigation and drainage) 38-42" White sand 52. 7.17 44" Dark hardpan (Palmetto roots undecomposed after thirty years) are associated with a surface layer of white sand which compacts, especially after rains, thus interfering with aera tion. Liming tends to keep such soil loose and friable thus improving leach ing and aeration. Leaching also greatDepth of Soil Sample 0-1" 0-6" 12" Tile 18" . 24" 30-36" 36-42" Soil Characteristics White sand crust Dark sand White sand (For irrigation and drainage) Dark hardpan Dark subsoil Dark subsoil Dark subsoil This marked reduction in soluble salts above the tile, with a considerable hold over of soluble salts in the subsoil be low the tile, was characteristic of pro files analyzed after the summer and hurricane rains of 1950. Soil profiles analyzed during the dry winter and spring seasons showed an accumulation of soluble salts at the surface as well as in the rr_ore dense layers below the tile. This summer a squash field was spotty in growth with a large percent age of the plants stunted and yellow. 39. 7.30 ly improved root and plant growth in these poor spots of celery. On October 25, 1950, after the heavy summer and hurricane rains, the fol lowing profile from a farm on Geneva Avenue, Sanford, ~as analyzed. Chlorides Total Soluble Salts (p.p.m. Cl) ( MHOS X 10-') pH 66. 42. 5.74 33. 12. 6.34 33. 23. 6.52 142. 30. 6.56 165. 33. 5.83 264. 55. 6.68 297. 60. 6.81 Most of the crop was disked in without harvesting a crop. A few vines sent out new, dark green growth after the hurricane rains. Surface soil from an old field on Celery Avenue, which has produced crop failures for at least the past five years was sent to the U. S. Regional Salinity Laboratory, Riverside, Califor nia, for analysis. Considerable work on saline soils of the West has been done at this Laboratory (1). The re sulting soil analysis showed a "soluble

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WESTGATE: SOLUBLE SALTS 121 sodium percentage" of 52, indicating that 52 percent of the total cation con centration was sodium. This report showed this soil from a poor pepper field to be "highly saline, and any crop would have difficulty." Leaching pre vious to planting was recommended. Soil samples from poor spots in a celery field on Beardall Avenue aver aged 74 p.p.m. of ammonia nitrogen, whereas adjacent good spots of celery in the same field showed only 5 p.p.m. of ammonia nitrogen. Soil samples from these poor spots failed to nitrify ammonia even when nitrifying bacteria were added unless lime was also added. Lumps of St. John's River "muck" and cover crop residues failed to decompose under the poor spots of celery in the field, indicating an inactivation of bac terial action in the soil. Leaching of the poor celery soils in crocks in the greenhouse with distilled water produced normal celery plants, whereas unleached soils from the same area produced stunted, chlorotic plants. Poor, stunted celery plants in the field, when leached with distilled water or artesian well water, put out new roots and made good growth, while unleached adjoining plants remained stunted. Liming of the stunted plants in the field improved the texture of the soil and favored new root and top growth. On February 8, 1950, a fall, celery seedbed area on Celery Avenue, planted to cabbage, was doing very poorly. The cabbage plants remained stunted, were all shades of yellow to purple, but would not respond to fertilizer. The cabbage was finally disked in without harvesting a single head. This grower, as he has often done in the past, then turned on his artesian wells, which have an average chloride (Cl) content of 613 p.p.m. Cl, and let them run through his tiled fields, including the seedbed area, for a solid month. At the end of this time, on June 2, 1950, this same seedbed area, which failed to grow cabbage, was again analyzed. The data obtained is as follows: Average Total Soluble Salts (l> IHOS X 10-') Depth of Soil Sample 0-1" 0-6" Feb. 8, 1950 Poor Cabbage Before Flooding 502. 153. Thus a large part of the accumulated soluble salts, at least of those in the top six inches of soil, were washed out of the surface soil by the well water and about 1.50 inches of rain by June 2. Celery seedbeds were again planted on this same area on July 4, 1950, and have Soil Samples , 0-" Good celery germination Poor celery germination. Bare June 2, 1950 Sept. 25, 1950 After Flooding New Seedbeds After summer 80. 65. Rains and Fertilizer 60. 32. produced excellent celery plants for this fall's plantings. On June 15, 1950, soil from seedbeds south of Sanford was analyzed when the plants were about three weeks old, with the following results: Average Average Total Chlorides, Solubl e Salts pH p.p.m. Cl. ( MHOS X 10-") 229. 21. 7.35 3695. 316. 6.92

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122 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Eight hundred parts per million of chlorides (Cl) have been re ' ported by the Central Florida Experiment Station as the upper limit for growth of celery under greenhouse conditions. Recent observations in numerous commercial celery fields in the Sanford area have shown poor growth of celery plants, probably due to malnutrition when the total soluble salts (including fertilizer salts) is below 20 MHOS X 105 in the top six inches of soil. Excel lent crop yields of 1000 crates or more per acre have been observed where the total soluble salts readings have been between 20 and 50 MHOS X 105 Read ings of above 85 MHOS are usually associated with black hearting, stunt ing and even death of the plants at the higher readings. On June 13, 1950, fourteen soil samples (0-6") were analyzed from an East Celery Avenue corn field soon after the corn crop had been harvested. Soil Sample Hairy Indigo, Cover Crop Depth Good germination and growth 0-1" Poor Germination. Dead and dying 0-1" On July 14, 1950, surface soil samples were collected from a west Sanford celery field which had been planted to Crotalaria as a cover crop following celery and corn. . Where the celery and corn had been stunted from high soluble salts the cover crop failed to germinate. On the edge of the field the cover crop showed very good germination and growth. After the summer rains set in, the cover crops responded nicely, and evenSoil Crotalaria, Cover Crop Sample Following Celery and Corn Depth Good germination and growth 0-6" Poor germination and growth 0-6" This sweet corn was grown on old tiled celery fields which analyzed as follows: Average Average Total Crates of Corn Chlorides Soluble Salts pH Per Acre (p . p.m. Cl) ( MHOS X 10-') 125. 254. 120. 6.23 25. 758. 203. 6.20 0. 1410 425. 6.49 Thus the corn yields were markedly reduced where the total soluble salts and chlorides were high in the soil. Even the lowest reading of 120 MHOS was probably too high for maximum growth of corn. Excellent corn has been observed along Celery Avenue with readings between 20 and 40 MHOS. On June 14, 1950, surface soil samples were obtained from good and poor spots of a hairy indigo cover crop following celery in a field along Celery Avenue. This field was irrigated with artesian well water containing 549 p.p.rr_. Cl. Chlorides (p.p,m. Cl) 230. 885. Total Soluble Salts ( MHOS X 10-") 52. 200. pH 6.39 6.52 tually covered even the bare spots form erly high in soluble salts. To date leaching by rain or well water, and the addition of liming materials have been the two treatments which have shown marked response in overcoming the effects of soluble soil salts in the tiled, sandy, celery fields underlain by hardpans in the Sanford area. The sandy soil above the tile and hardpans is relatively easy to leach, but the more Avera ge Average Total Chlorides Soluble Salts pH (p.p.m. Cl) (MHOSX 10-') 147. o. 6.61 525. 110. 6.54

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BROOKS AND CHRISTIE: STRAWBERRY NEMATODE 123 impermeable and retentive layers below the tile are much more difficult to wash out . This reserve supply of salts which remains in the lower layers of soil, even after summer and hurricane rains , is then available to be brought back to the s urface la ye r s b y ca pillarit y and evaporaSalin e S pot in Ce l ery F ie ld, Sanfo r d , Flor i da . tion during the comparatively warm, dry winter growing seasons. Acknowledgments The author wishes to take this oppor tunity to thank Dr . Nathan Gammon, Soils Chemist, Gaine s ville, for the sodium determinations , Dr. George Thornton, Professor of Soils, Gainesville, for his work on nitrification, and Dr. A . D . Ayers, U. S . Regional Salinity Labora tory , Riverside, California, for his ad vice and suggestions regarding saline s oil s. LITERATURE CITED 1. R1 C HAR DS , L. A . Di agnos i s an d Improvem e nt of Sa Lin e and A lk a li Soils. U. S. R e gional Salinity Labomtory, Ri vers id e, California. 1-157 . 1947 . 2 . STUBBS , SIDNEY A . Study of the Artesian Wat e r Supply o f Seminol e County, Florida. Proc dings of t h e Florida Academy of Sci e n ces. Vol. II: 24-36. 1937. A NEMATODE ATTACKING STRAWBERRY ROOTS A. N . BROOKS, Pl ant Patholog ist St raw be rry L abora to ry Plant City J. R. CHRISTIE, Senior N ema tologist U. S. Depa rtment of Ag ricu ltur e Sanford This disease was first noticed in straw berry fields during the fruiting season 1946-47. Affected areas in a field were small at first but gradually increased in size in a somewhat circular pattern until large areas became involved. In a few cases all the plants in a field were affected. The affected plants became semi-dor mant, no new growth being apparent . Edges of leaflets became dark brown, a typical plant symptom of root injury . There was a gradual dying of leaf tissue from edges to midribs. Plants thus dec lined gradually , sometimes lingering for s everal weeks before death finally took place. The root systems of affected plants were lacking in fine feeder roots. The cortex of the remaining larger roots was dead but in most cases the steles or central cylinders remained alive for some time subsequent to destruction of cortex. Later st udie s showed that ro.ot tips were killed then lateral roots developed and their tips in turn were killed. This re sulted in the production of root systems consisting of coarse roots with knobby tips . Roots of affected plants were examined for nematodes but none were found in or on the roots . Isolations made from such roots gave the usual display of various soil fungi but none appeared consistent ly . Affected plants were collected for future use. The roots were carefully washed under running water and the plants then set either in treated soil in

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124 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 the greenhouse or in field beds at the Strawberry Laboratory. All plants thus treated put on normal root systems. This proved rather definitely that the causal organism was not of fungal or bacterial origin and that if a nematode was in volved, it must be mostly ectoparasitic, i.e. it did not enter the root tissues. Field soil from around the roots of affected plants was collected and placed in 6-inch pots in the greenhouse. Cucum ber and oats were planted in this soil as a catch crop for the meadow nematode, which was suspected at that time as being the casual organism. As soon as sufficient roots had developed they were removed from the pots and carefully shaken free of most of the soil. The re maining soil was washed from the roots irtto beakers and the clean root s were allowed to soak in water over night . Ex amination of these roots the following day showed that very few nematode s were present in or on the roots or in the water in which the roots had been soak ing. At the same time many nematodes were found in the water which had washed the roots free of soil. This also tended to show that the nematode in volved was estoparasitic. During December 1946 and January 1947 the soil fumigant D-D was tested in several of the affected fields. The fumigant was injected into the soil near affected plants. Injections were made at depths from 4 to 10 inches and at various distances from the plants, from 4 to 7 inches. Rates of application varied from 3 to 8 ml. per injection. None of. the plants were killed by this treatment and a high percentage of them subsequently de veloped normal root systems. Again, these results tended to show that some ectoparasitic nematode was causing this root trouble. CAUTION: THIS TREAT MENT OF BEDS CONTAINING STRAWBERRY PLANTS IS NOT A RECOMMENDED PROCEDURE. It was not until the season 1949-50 that a correct identification was made of the nematode which might be the cause of this root trouble. It had been incor rectly reported as the meadow nematode, Pratylenchu s pratensis. In December and January two surveys were made of affected and non-affected strawberry fields in Hillsborough County. Specimens of diseased and also ap parently healthy plants were collected from affected fields together with soil samples, 1-pint each, from the rhizo spheres of these plants. These were ex amined by Dr. Christie and the sting nematode, B e lonolaimus gracilis, Steiner, was found in almost all soil samples. However, the number of nematodes in the soil samples from around roots of plants showing symptoms of the disease was usually much greater than from plants which were apparently healthy . This was especially true in the December survey. Only one case of nematodes within the roots was observed and these nematodes were in the larval stage. No sting nematodes were found in plant or soil samples from fields in which none of the plants displayed symptoms of the dis ease. B. gracilis is rather easy to identify because it is long, almost 2 mm., and slender with an extremely long stylet, 0.157 mm. long as compared for example with that of the meadow nematode which is only 0.015 mm. long. During the spring of 1950 specimens of B. gracilis were found in soil samples from affected strawberry fields in Polk, Hardee and Manatee Counties in addi tion to Hillsborough County. In the summer, a few specimens were found in soil samples from around roots of corn and crabgrass growing in fields in which strawberry plants had been affected dur ing the winter. Thus far B. gracilis has been collected from only one of the nur sery fields in east Hillsborough County.

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SPENCER AND JACK: NITROGEN TRANSFORMATION 125 During the past three years strawberry growers have found that soil fumigation, either solid treatment before bedding or row treatment as the beds are made up, has enabled them to grow good crops of strawberries on land in which . this root trouble has been destructive to previous strawberry crops. NITROGEN TRANSFORMATION IN SEEDBEDS AS AFFECTED BY NEMATOCIDAL TREATMENT ERNEST L. SPENCER AND AMEGDA JACK Florida Agricultural Experiment Stations ' Vegetable Crops Laboratory Bradenton Infestation of soil by nematodes is one of the major problems confronting vege table growers in many sections of Flor ida. The root-knot nematode, which penetrates plant roots and causes large irregular swellings, is the most striking and perhaps best known of this group of pests. Economic losses due to nematodes are extremely difficult to evaluate since the damage depends on the stage of growth of the plant at time of attack and the degree of infestation. Affected plants are more susceptible to other para sitic and physiological disorders than are healthy plants and usually produce low yields of inferior quality. Because of the economic importance of these pests, considerable interest has been shown in the development and use of chemical fumigants having nematoci dal value. These materials have been tested quite extensively here in Florida, especially on vegetables and tobacco. The effectiveness of such materials as Larva cide or chlorpicrin, DD or dichloropro pane-dichloropropylene, EDE or ethylene dibromide, and MC-2 or methyl bromide mixture, has been clearly demonstrated. This Laboratory is still hesitant about making definite recommendations on soil fumigation with these new chemicals, even though our early tests on this phase have been most encouraging. There is still much to be learned about these fumi gants. Some of the questions as yet unanswered are: Is it safe to use them repeatedly each season? Do they leave any residue in the soil which in time may become toxic? What effect do they have on other soil organisms, especially those known to be important to soil fer tility? A few observations have been recorded from time to time on some of these poirits. In the Annual Report of the Florida Agricultural Experiment Station for 1948, Burgis and co-workers reported that fumigation of vegetable seedbeds with 2, 4-D, chlorpicrin or a uramon cyanamid mixture altered the amount of ammoniacal and nitrate nitrogen present in the soil. Similar observations for DD on tobacco acreage have also been re ported by Kincaid and Volk in Press Bulletin 655 of the Florida Agricultural Experiment Station. The object of this paper is to report briefly the results of a study into some of the factors involved in the nitrogc:n transformation in seedbed soil following nematocidal treatment. When soil organic matter decomposes, ammonia is liberated and under favorable soil conditions is then converted to nitrate. This so-called nitrification reaction has long been con sidered as a biological process, and it is this process that is apparently affected by soil fumigation. The fumigation materials used in this study were chlorpicrin, . 2 ; 5 pounds per 100 sq. ft., ethylene dibi:omide ( Soilfume 60-40), 13 gallons per acre, and methyl

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126 FLORIDA STATE HORTICULTURAL SOCIETY, 19.50 bromide mixture, (MC-2), at 2 pounds per 100 sq. ft. All materials were ap plied as recommended by the manufac turer, 14 days prior to seeding. The treatments were replicated on two dif ferent soil types: Manatee fine sandy loam (heavy phase) with a pH value ap proximately 7.0 and Leon fine sand with a pH about 5.5. All beds were sampled 10 times over a period of 70 days, mostly at 7 day inter vals. In sampling, special care was taken not to carry soil from one plot to another. Several types of analyses were made, but those reported in this paper include nitrate-nitrogen and ammoniacal nitrogen contents at time of sampling, and the nitrifying power of the soil. The chemical analyses were made according to approved colorimetric methods. The nitrifying power was measured by de termining the amount of nitrate formed from ammonia during a 27-day incuba tion period. All experimental data have been subjected to statistical analysis. Accumulated data (Figure 1) show quite clearly that all fumigated plots were higher in ammoniacal nitrogen than were the check plots. This difference held for 70 days but it was statistically significant for only the first 42 days fol lowing fumigation. This trend has been observed previously but these data show the duration of this difference. The peak in the curves nine days after fumigation was due to the application of 3000 pounds per acre of fertilizer. The nitrate data (Figure 2) show the reverse to be true. The nitrate-nitrogen content of the check plots was higher than that of the fumigated plots. This difference was statistically significant with both chlorpicrin arid methyl brom ide. As with the ammonia, the nitrate value rose sharply nine to 14 days fol lowing fumigation, but this was due to fertilization four days after fumigation. At the same time these data on nitro gen were being collected, certain microbiological studies were made with the soil samples as they were taken. Time does not permit a complete discussion of these results but it might be well to . call attention to the nitrification studies since this paper deals primarily with nitrogen transformation in the soil following fumigation. Aliquots were taken from each soil sample immediately after sam pling and placed in Erlenmeyer flasks with known amounts of sulfate of am monia and lime. The lime was necessary to control the pH of the aliquot and pre vent it from becoming too acid. A'fter incubation for 27 days the amount of nitrogen transformed from the ammonia cal to the nitrate form was determined. A graphic presentation of these results is shown in Figure 3. As in the other two figures, the dif ference between the ethylene dibromide treated plots and the check plots was not statistically significant. However, the nitrifying power of the soil in the ethy lene dibromide plots was lower than that of the check plots at each date of sam pling for the first eight weeks with but one exception. There was relatively lit tle difference between the chlorpicrin and the methyl bromide-treated soils, but samples from both of these treatments were significantly poorer than the sam ples from the check plots in their ability to oxidize ammonia to nitrate. This effect was evident for seven or eight weeks after fumigation. In general, the low nitrate-nitrogen values and the high ammoniacal-nitrogen values observed following soil fumigation seem to be due to the action of these chemical fumigants on the nitrifying organisms in the soil. The longevity > of this effect varied with the material, but for the most part all materials were effective for at least six weeks. The question now arises as to what practical significance may be attached to these results. It has been known for some time that certain plants, such as

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SPENCEH A 1 D JACK: NITHOGE 1 THA 1 SFOHMATIO ; 127 the tomato, are able to absorb ammo niacal nitrogen during early stages of growth if the soil pH is near the n eutra l point. Therefore, on soi l s with high pH, the tomato plant shou ld show no abnor malitie s due to the up,,et in nitrogen transformation following soi l fumiga tion. However, on acid so il s the tomato plant might actually s h ow a nitrogen deficienc y even though the total inorganic nitrogen content ma y be adequate. This condition may be readily remedied in one of two ways: dolomitic lime stone can be added prior to fumigation, or a balanced fertilizer, in which mo st of the inorganic nitrogen is present as nitrates, can be u sed until the nitrifying power of the soil ha s returned to normal. There are sti ll man y gap s in our knowledge concerning soil fumigation . Our laborator y studies show that these fumigants a lso exerted a fungicidal ac tion in the soil. Certain soi l fungi such as Trichoderma, Fusaria and Penicillia are sens iti ve to fumigation. MC-2 and chlorpicrin were very effective, destro y ing all fungi in the treated areas. For as long as seven month s after fumigation the fungu counts on these treated plots were below those on untreated plot s . It was of interest to observe that the first fungu to resume growth on these plots was a species of Trichoderma. This growth rapidly increased above the growth of this spec i es found in the un treated so il s. Treatment with EDB showed little effect on fungus popula tions. The significance of these observations on seedbed fumigation can not be com pletely evaluated at the present time . We can say, however, t h at at the present time the grower shou ld be wary of any cultural practice t ha t involves repeated chemical fumigation of the so il. A"MON I ACAL NI TROCCN CONTCNT POUNDS PC:R ACR[ ... z IJ ... z 0 u z IJ u 0 a: ... z C u C z 0 s IC C CHC:CK CHLORP COB MC-2 . 30 40 50 60 DAYS ArTCR rUMICATION Figii1e 1 J 70

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128 ,so r IJ ... z 120 z u u 0 a:: ... z IJ ... < IIIC ... z 80 FLORIDA STATE HOHTICULTURAL SOCIETY, 1950 r _I NITRATC-NITROCEN CONTENT POUNDS PCR ACR[ CHCCK "'= 7 CHLORP ---. I coe i MC-2 ~-,,--/ --_ _ _:._,,, /" -::-~ -;;:::;..: .... -0L-----'-----'----....,..... ----=-----=-= 0 I 0 20 30 410 50 60 70 ... z w ... z 0 u z w " p a: .... z 'I u .... < a:: ... z 200 , 1 I DAYS ArT[R rUMICATION F igure 2 NITRATE-NITR0CEN,PPM, AfTER 27 DAYS NITRlflCATI0N I' ,/ "': ': V I 20 30 l 40 CHECI( CHL0RP EOB MC-2 I ----I 50 DAYS AfTCR fUMICATION Figure 3 60 70

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STONEH: GHAYWALL OF TOMATOES 129 GRAYW ALL OF TOMATOES WARREN N. STONER Florida Agricultural Experirnent Stations Everglades Experirnent Station Belle Glade Introduction An abnormal condition of tomato, known locally as graywall in South Flor ida, has been observed for many years in small proportions. Within the last few growing seasons losses sustained from the condition have been high enough to cause some growers to think seriously of abandoning tomato culture. Some of these men have known of gray wall as a curiosity for thirty years and in the past have called the condition "nitrification." They now believe the condition is increasing in severity and amount. Graywall at the present time is one of the important problems facing the tomato industry in Florida. Review of Literature Abnormalities of tomato quite similar to graywall in South Florida have been described by several authors in wid1::ly separated geographical locations. In England Bewley and White (1) have described blotchy ripening of to mato and attributed it to four different causes. Two of these conditions, stripe and greenback, can be easily separated from Florida graywall. One of the other two, blotchy ripening, caused by infec tion with Aucuba mosaic virus, resem bles graywall in some respects, but no mention is made of internal browning. Their description of true blotchy ripen ing, however, corresponds very closely to Florida graywall and internal browning is present. These authors offer con vincing proof that true blotchy ripening is due to a deficiency of available potas sium and nitrogen. Selman's (11) publication in 1943 on the int~rrelation between mosaic infec tion, soil conditions and blotchy ripening shows a relationship between the condi tion and water retaining properties of various soil mixtures. He also concluded that extreme fluctuation of the water content of the soil (substrate) is asso ciated with blotchy ripening. These ex periments were conducted using the same fertilizer on all plants and holding half of the plants free of the virus for con trols. Thus there is more than one vari able but the results obtained in the con trols indicate soil type and moisture in fluence the amount of blotchy ripening alone or in combination with infection with what he calls tomato mosaic virus. In New Jersey, Haenseler (6) and Holmes (7) described a disease of tomato under the name of "internal browning of tomatoes." The symptoms of the condi tion are very similar to graywall as described by Conover (2). There are certain differences, however. Graywall is not associated with any portion of the fruits (i. e., the portion nearest the stem) as in the case in New Jersey . No angu larity of the fruit shoulders has been observed. The stem scar and pedicles are not abnormal in any way, and no foliage symptoms have been observed in the case of graywall. Holmes (8) has published that internal browning in New Jersey as described by Haenseler is due to a strain of tobacco mosaic virus but in no case has a virus been consistently associated with graywall plants in Florida. Young (14) described a condition called internal browning and core rot occurring in Texas. The symptoms are very similar to those seen in graywall, with the exception that the cores have not been as severely affected in Florida : . as are those shown in Young's !Ilustra tion of this condition in Texas. Internal

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130 FLORIDA STATE HOHTICULTUHAL SOCIETY, 19.50 browning and core rot symptoms, accord ing to Young, probably are caused by the same factors causing blossom-end rot. The condition in Texas has been corre lated with periods of abundant rain. Varietal resistance to blossom-end rot has been demonstrated by Young (13), and internal browning symptoms are illustrated. Foster and Tatman (5) and Foster (3) (4) have recorded internal browning of tomato associated with pocketing or puff ing and blossom-end rot, and have corre lated these conditions with soil nutrition, soil moisture, air temperature and light duration. No such correlation has been possible with graywall, and it has been difficult to find blossom-end rot in the fields badly affected with graywall. In California a condition called gray wall or thinwall has been described by Lorenz and Knott (9). Their experi ments demonstrate that the described condition is due to a combination of in tense light and a heat effect. The symp toms described for thinwall indicate it is entirely different from Florida graywall, and no mention is made of the occurrence of internal browning in the California condition. For the sake of clarity in this paper, the term thinwall is used for the California condition and graywall for the Florida condition. Syrnptorn.s The only known symptoms of graywall are a disintegration and browning of the internal tissues of the fri1it. The dis coloration may involve ohly a single vascular strand or most of the vascular bundles, and if the condition has prog ressed a great deal, the placental tissue and the core become involved. Generally, the browning stops at the abscission layer of the trusses; however, it has been seen to extend into the main stem up and/or down (2 to 4 inches). In green or pink fruits this internal browning is seen from the outside as pale gray to brownish translucent spots varying in size. The common name, graywall, is derived from the external appearance of the condition in green or pink fruits. The more severe the internal breakdown the darker the spot. When the fruit ripens the color of the spot becomes more intense. Uneven ripening is common and is conditioned by the progress of the internal browning. When the fruits are fully ripe and the condition well ad vanced, the spots may become sunken and roughened (Figure 1). The condition does not affect the palatability of the fruit, but the appearance prevents sale. There is no regular sequence in the pattern of the location on the plants of the fruits affected. The condition can occur in any of the fruits set on any of the hands anywhere on the plant and has been seen to involve a single fruit or all fruits of a given hand. Graywall has occurred, for example, in some of th e fruits on the first hand, then not shown in the second hand, yet has reappeared in the third or later hands. No foliage symptoms have been seen in plants bear ing graywall fruit. In fact, some of the best looking plants in the fields have been the ones bearing the most graywn II fruits in quantity and severity of the condition. Field Observations Graywall in Florida has been observed t . o occur in fields from Vero Beach south to Homestead on the East Coast and in the tomato-growing areas at Ruskin . Observations of graywall in the field to date have failed to reveal any consist ency. Graywall has been found occurring in the fruits of plants growing on sand, marl and sandy-muck type soils under a wide range of fertility and cultural pro grams. It has been seen in fields under various spray programs. The condition occurs both where the plants have been drilled in the field and set from seedbeds. It has been seen on so-called new land

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STONER: CRAYWALL OF TOMATOES 1 31 and on land that has been under cultiva tion before . It has occurred in both fall and spring crops on both staked and un staked tomatoes. There ha s not been any correlation between the condition and location in the field, ( i.e., high or low I 3 4 s pot s ) . It can occur generally through out the field or be concentrated in a small sect ion. In only a few cases has graywall exhibited a typical gradient of location as would be expected in the case of dis eases caused by known pathogens. The 2 5 Figure 1. Rutger's tomato fruits affected with the graywall condition. Numbers 1 and 2 are 1nature green. Numbers 3, 4 and 5 are red ripe. Note the progressive darkening of color and depression of the sur f ace of the spots located over the in ternally browned tissues. Wall tissues surrounding these spots often fa il to color normally.

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132 FLOHIDA STATE HORTICULTURAL SOCIETY, 1950 condition has been observed in several varieties, therefore it is not necessarily a varietal phenomenon. No clear-cut association with weather conditions has been possible, although in two instances it is believed heavy rains may have influenced the appear ance of the condition in hydroponically grown tomatoes at Hypoluxo, Florida. In these instances the rains prevented the growers from feeding the plants with the nutrient solution for four days, and in order to maintain areation in the beds the rain water was pumped off daily. At the end of this rainy period usual cul tural practices were resumed. Eight days later 90 percent of the fruits being har vested were affected with graywall. These fruits were on the first and second hands. This high percentage gradually de creased for the next week, and at the end of this time the condition was cleared up in both cases, and a normal crop was taken the rest of the season. Method of Procedure Research on graywall at the Ever glades Experiment Station has been con fined to attempts to determine its cause. Repeated microscopic examinations of plants bearing graywall fruits have failed to reveal any visible pathogen, and no correlation of occurrence could be made with nutritional or climatic factors. In view of the above facts and the findings of Selman (11) and Holmes (8), it was logical to suspect a virus of being the causal agent. A field located at Loxahatchee, Florida, on Broward fine sand soil was found to be heavily affected with graywall in January 1950. Six plants bearing graywall fruits were selected at random in this field to be used for the collection of source material in the experiment. The plants adjacent in the row to the selected source plants were pulled to try to prevent possible field spread of viruses to the source plants. During the remainder of the season the source plants were under the same cultural practices as the rest of the crop with the exception that the pickers were not allowed to harvest the fruits. All of the graywall material used in the experiments was taken from these six plants. Each time material was taken all mature fruits were picked and in each instance one or more of the plants were bearing graywall fruit. To prevent possible spread of virus within the source group of plants while collecting and in later handling with the test plants in the greenhouse, 70 percent ethyl alcohol was used freely to wash the hands of the in vestigator each time before going on to the next operation. 100 percent checks were maintained in the initial experi ments. Later in order to conserve green house space only 20 percent checks were used. All plants used in the greenhouse were potted in porous red clay pots in mature peat soil and fertilized weekly with a complete commercial fertilizer of a 6-6-6 composition plus the minor ele ments, boron, copper, magnesium and zinc. Mechanical Inoculations Mechanical inoculations by the car borundum method, described by Rawlins and Tompkins (10), were made to three plants each of tomato ( Groth ens Globe), Turkish Tobacco, Nicotiana glutinosa, squash (Zuchinni) and cucumber (Early White Spine) from each of the six source plants on January 30, 1950. The test host range as listed was chosen so a check could be maintained on the source plants for possible infection with the southern strain of cucumber mosaic which was prevalent in the Loxahatchee area. At the end of thirty days no local or systemic symptoms had been observed in any of the rapidly growing test plants, and all except the tomatoes were dis carded. Two more similar sets of inocu lations were made from the described field source plants, one on February 28, 1950, and the other on March 9, 1950.

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STONER: GRAYWALL OF TOMATOES 133 These two series were treated exactly the same as the first, and again no symp toms could be observed at the end of thirty days. The tomato plants in these last two series were also held to see if fruit symptoms would develop. Thus the total of all plants inoculated from the field source plants was 270, 54 of each of the host range plants. Harvest of the fruits from the first 18 mechanically inoculated January tomato plants began on April 18, 1950, and ended on June 5, 1950. These fruits were harvested when fully red ripe. No external symptoms of graywall were observed and all of the fruits were cut in cross section and examined for internal browning. Again no symptoms were seen. A total of 77 fruits was taken from this series. Har vest from the 18 tomato plants of the February 28, 1950, series of mechanically inoculated plants began May 6, 1950, and ended July 3, 1950. A total of 88 fruits was taken and none showed any external or internal symptoms of graywall. The third series of 18 tomato plants mechani cally inoculated on May 9, 1950, were harvested from May 10, 1950, to July 3, 1950. Seventy-four fruits were taken and none of them were affected by gray wall. Thus a total of 239 fruits was har vested from 54 tomato plants mechanical ly inoculated with sap expressed from six field plants known to be affected with graywall. These fruits were taken from the first to the fifth hands. In the first series the fruits were harvested when graywall was prevalent in the fields. Careful external and internal examina tion failed to disclose any symptoms of graywall in any of the 239 fruits har vested. Grafting Investigations Since local or systemic symptoms had failed to develop in the first mechanical inoculation series, there was a possibility that graywall could be due to what Watson and Roberts (12) have defined as a persistent virus. Grafts were made to three healthy tomato plants from each field plant to check on this possibility. Two of the grafts in each case were cleft grafts, the other was an inarch, (Figure 2), and all of the grafts were suc cessful. These plants were observed in the greenhouse for symptoms from February 14, 1950, to August 1, 1950. No foliage symptoms were seen, and a total of 87 graywall fruits was harvested from April 21, 1950, to July 27, 1950. Graywall was prevalent in the fields dur ing the first half of the harvest period. A second series of grafts were made on the 13th of April, 1950. Inarching in the first series had produced more vigor ous plants, so this method was used ex clusively in the second series. Four plants were grafted with scions taken from each of the six source plants. A total of 104 fruits was harvested from these 24 plants from June 13, 1950, to August 3, 1950, and none developed external or internal symptoms of graywall. A grand total of 191 fruits was har vested from 42 plants to which scions, taken from plants bearing graywall fruits, had been grafted. No symptoms of any kind were observed in the fruits or foliage and the plants grew normally. Cutting Studies Early in April, 1950, field operations called for clean up and plowing under the planting from which the source plants had been chosen. The six source plants were dug, brought in from the field, pruned and transplanted to pots to see if they could be carried on in the green house. At this time several cuttings were taken from each source plant. These cuttings were rooted in clean sand and transplanted to pots two weeks later. The cuttings were held to see if any graywall fruit would develop. All of these cuttings grew and appeared quite normal, and a total of 59 fruits was har

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1 34 FLOR ID A STATE HORTICULTURAL SO CIETY , 1950 F igure 2. lna rch c utting graft f oimd to be most successful in graywall investi ga tions. S cion and sto c k h e ld together with ordinary g ra ft ing ru bb er . Th en the entire graft was cov ere d with low me lt in g point grafting w a x . A larg e p e rcentag e of the scions rooted in the flasks a nd l ived th rou gho ut the investig at i ons.

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STONER: GRAY\VALL OF TOMATOES 135 vested from them from July 10, 1950, to August 3, 1950. All of these fruits were harvested when fully red ripe, and no symptoms of graywall could be observed in them. Yields From Transplanted Field Source Plants The source plants potted from the field were in a declining state and did not grow well. The field source plants 1 through 5 did blossom, however, and produced a total of 15 fruits all free of graywall. Plant No. 6 died, and plant No. 5 developed typical tobacco mosaic symptoms after handling, although its cuttings were free of the disease. Mechanical inoculation from plant No. 5 to Nicotiana glutinosa produced an abundance of the local lesions typical of those produced by tobacco mosaic on inoculation to this host. Summary Symptoms of the condition of tomato known in South Florida as "graywall" are described. Repeated microscopic examination of plants bearing graywall fruits have failed to disclose a visible pathogen. Field observations of gray wall have failed to show any consistent conelation between the condition, cli matic factors, varieties, or cultural prac tices. Mechanical inoculations from field plants bearing graywall fruits to a selected host range failed to produce any systemic or local symptoms. Fifty-four tomato plants mechanically inoculated produced 239 graywall-free fruits. Forty two tomato plants grafted with scions taken from field plants bearing graywall fruits developed no symptoms of any type and produced 191 fruits all free of graywall. Cuttings made from field plants affected with graywall produced 59 normal fruits. Five full-grown field plants which had borne graywall fruits throughout the experiments were pruned, all fruits were removed and then trans planted to pots in the greenhouse. These plants then prodticed 15 graywall-free fruit. Conclusion The investigations indicate that gray wall of tomato in South Florida is not caused by a transmissible pathogen. A review of the literature shows that con ditions similar to graywall in South Flor ida occur in widely separated locations. Many of these conditions have been shown to be caused by physiological re actions to varying environmental factors. It is therefore reasonable to believe that further investigations in Florida will demonstrate that graywall is a physio logical condition, and correlation of gray wall with environmental factors may be possible in the future, even though such correlation has not been clearly shown to date. The author would like to acknowledge with thanks the assistance of Mr. Wil liam D. Hogan, formerly Assistant Plant Pathologist, Everglades Experiment Sta tion, during the later portion of the in vestigations herein described. The photographs for the figures were taken by Mr. Grant E. Averill. LITERATURE CITED J. . ll>:WLEY, \V. F., nnd H. L, \VntTE. Some nutritional disorders of the tomato. Ann. Appli. Biol. 13: 323-338. 1926. 2. CONOVER, ROBERT A. Vascu1ar hrowning jn Dade County, Florida, green-wrnp tomatoes. U. S. DeJJt. Agr. Pl. Dis. Reptr . 33: 336-337. 1949. .'3. FosTER, Alt.THUR C. Environmental conditions influencing the development of tomato pockets or puffs. (Ahstract) Pliytopat/1. 27: 128. 1937. -1. FosTER, A. C. Effect of environment on metaholism of tomato plant as related to develop ment of blossom-encl rot of the fruit. ( Ahstrnct) Pl1ytopatl1. 29: 7. 1939. .5. FOSTER, ARTHUR C . , and EVERET'.!' _ c. TAT:\IAN . Environmental conditions influencing the de velopment of tomato pockets or puffs. Sciencu 86: 21-22 . 1937. 6. HAENSELER, C. M. Internal browning of toma toes in New Jersey . . . U. S. Dept. Agr. Pl. Dis. ReJ>lr. 33: 336-337. 1949. 7. HOLMES, _ FRANCIS 0. Association of strains , of tobacco-mosaic virus with internal browning in tomatoes. U. S. Dept. Agr., Pl. Dis. Reptr. 33: 338-:WJ. 1949, .

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136 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 8. ------Internal-browning disease of to mato caused by strains of tobacco-mosai c viru s from Plantago. Phytopath . 40 : 487-492 . 1950 . 9 , LonE N Z, O. A . , and KNOTT , J , E. Studi es of Gra y -Wall of tomato . Pr o c. Amer . Soc . Il o rt. Sci. 40: 445-454. 1942. 10. RAWLINS, T, E., and TOMPKINS, C. M. Stud ies on the eff e ct of carborundum as an abrasive in plant viru s inoculations . Pytopath. 26: 57 8 587. 1936 . 11. S E LMAN, I . W . Th e int e rr e lation b e tw ee n mosai c inf ec tion, soil co nditions and blot c h y ripen i n g . Rep. Exp . Sta., Cheshunt. 46-52 . 1943 . 12 . WAT SON, M . A., a nd ROBERTS , F. M . A c o m p a r a t i v e s tudy of th e transmission of Hy os cyamu s virus 3, potato Y and cu c mnber vin,s 1 by the vect o rs Myzus pers ic a e ( Sulz), l\f, circ11mflern s (Buckton) and Macro s iphum gei. (Koch). Pro c . Roy. S o c. Lond., B 127: 543-577. 1939 . 13. You N G , P. A. Vari e tal r e si s tance to blossome nd rot in tomat o es . Phyt o pat . h , 32: 214-220 . 1942 . 14 . YoUNG, P . A. Toma to di seas e s in T e x n.c; . T e xa s A g r . Ex p . Sta. Gire . 11 3. Hl46 . QUALITY OF FLORIDA POTATOES AND SOME OF THE FACTORS AFFECTING QUALITY R. E. L. GREENE Florida Agricultural Experiment Station Gainesville The five southeastern states of Flor ida, Alabama, South Carolina, North Carolina and Virginia began in 1947 a regional study under the Research and Marketing Act of "Marketing Early Irish Potatoes." Work has been devoted to a subproject "Spoilage in Marketing Early Irish Potatoes" to determine the causes of losses in handling potatoes. The states have been assisted by the Bureau of Plant Industry, the Bureau of Agricultural Economics, the Federal Inspection Service, the Railroad Perish able Inspection Agency, the Western Weighing and Inspection Bureau, co operating receivers in terminal markets, and shippers and farmers in various potato producing areas. To obtain data on factors causing losses in handling potatoes, special lots were followed from the time they were dug in the field, through the grading and packing shed, to the terminal market, and in many cases through re tail stores. Records were obtained on weather conditions at time of digging and practices in handling potatoes both in the field and in the packing sheds. Samples were collected at vari ous points in the marketing process to measure the extent of damage and where it was occurring. These data provide a record of usual practices in handling potatoes and the effect of these on losses and quality. Study of Grade Qualities of Potatoes in Retail Stores In the above study, it was possible to follow only a small percentage of the test lot s through retail stores. Data on these lots gave some information on the condition and quality of potatoes in stores but it was felt that additional data were needed. Therefore, a special study was conducted in Pittsburgh in 1950 to determine the grade qualities of potatoes displayed for sale to con sumers in retail stores. The Pittsburgh market was chosen for the study be cause the Bureau of Agricultural Eco nomics had in progress a fruit and vegetable survey in 30 stores selected to represent various conditions in that market. They consisted of small, medium and large stores and represent ed various types of independent and chain stores. It was thought th a t the results of the two stud_ies would supple ment each other. In the study of grade quality, samples were collected and examined from lots of potatoes displayed for sale in the cooperating stores. Each store was visited twice a week from March 1 to

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GREENE: POTATO QUALITY 137 June 30, 1950, and a 10 to 15 pound sample purchased from each display of potatoes . For example, if Maine pota toes were offered for sale in both bulk and consumer packages, a sample was purchased from each lot. Samples were collected from Monday through Friday . of each week and 12 stores were visited each day. The schedule for vi s iting the stores was designed to give a repre sentative sample of potatoes on display throughout the day and for variom; days of the week. The stores were visited so as to include a sample by size and type each day and visits to individual stores would rotate as to the day of the week and ti~e of day. All samples were carried to a central laboratory and each was graded by a Federal Inspector ac cording t , o Federal grading standards. Each potato was sized and analyzed in detail for external and internal defects, each type of defect being scored sepa rately. The degree of severity of each type of defect was estimated and record ed as s e rious damag e , damage or injury. After each lot was graded, all defects were cut out and the amount of material removed was weighed to get an objective measure of loss due to defects. During the study over 3,000 sample8 of potatoes were collected and examined. The data are now in the process of being analyzed . Results presented here are preliminary and cover only the period March 13 to June 2, 1950. They are based on a simple average of all samples collected as samples for individual stores have not been weighted by volume of potatoe8 sold in the store. The period covered includes the bulk of the move ment from Florida. In this paper, I would like to discuss the average grade defect of Florida potatoes and show how they compared with other potatoes on the market during the same period. Next, I would like to discuss the type of de fects in different varieties of potatoes from Florida and, from our previous work, show some of the things we found that caused some of the damage. Average Grade Defects Five hundred and fifteen samples were collected between March 13 and June 2, 1950, from lots of Florida potatoes dis played for sale in the 30 cooperating stores. The average grade defects of these potatoes was 16 percent, of which 5 percent was scored as serious damage and 11 percent as damage (Table 1.). In addition to grade defects, 6 percent was scored as injury, making a total of 22 percent for all d e fects. The average TABLE 1. AVERAGE PERCENTAGE TOTAL GRADE DEFECTS AND OTIIEI\ FACTOHS , BY STATES OF O1\IGIN, FOR POTATOES IN 30 HETAlL STORES IN PITTSBURGH, PE N NSYLVANIA, l\IAI\CH 13-JUNE 2 , IMO. C a liMain e Idaho Item Florida Alabama fornia Prepacked Bulk Prepa c k e el Bulk Number of samples 515 114 210 595 255 117 328 Average percentage defects: Percent serious damage 5.5 10.5 11.5 5.6 7.4 7.1 11.8 Percent damage 10.9 10.0 4.7 7.8 12.3 13.1 19.4 Percent total grade defect 16.4 20.5 16.2 13.4 19.7 20.2 31.2 Percent injury 5.8 3.6 1.0 3.7 5.8 6.0 7.3 .. Percent total defects 22.2 24.1 17.2 17.1 25.5 26.2 38.5 Percent waste 4.4 8.9 8.9 4.0 6.1 5.9 ~ 0 . Average retail price (cents) 6.91 7.22 5.93 4.19 5._Q7 7.16 . 7,25

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138 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 grade defects for potatoes displayed from certain other states during this same period was 20 percent for Alabama, 16 percent for California, 13 percent for Maine in consumer packages and 20 per cent in bulk, and 20 percent for Idaho in consumer packages and 31 percent in bulk. The percentage of waste due to defects as shown by the material that was cut out varied in relation to total grade defects but was affected by the propor tion classified as serious damage and damage. For example, the average grade defects of Florida and California potatoes was the same, 16 percent. The propor tion scored as serious damage and dam age was reversed being 5 percent serious damage and 11 percent damage for Flor ida potatoes and 11 percent serious dam age and 5 percent damage in California potatoes. The average percentage waste amounted to 8.9 percent in California but only half as much, or 4.4 percent, in Florida potaoes. The average waste in potatoes from other states was 8.9 per cent for Alabama, 4.0 percent for Maine prepackaged and 6.1 percent for bulk potatoes, and 5.9 percent for Idaho pre packaged and 9.0 percent for bulk pota toes. Variation in Grade Defects of Florida Potatoes by Varieties The average grade defects of Florida potatoes varied considerably by vari eties. Pontiac with grade defects of 12 percent was lowest, Red Bliss was sec ond with 16 percent and Sebago highest with 23 percent. The average waste due to defects was 3 percent in Pontiac, 5 percent in Red Bliss and 6 percent in Sebago. With the exception of Maine potatoes that were prepackaged at the shipping point, the average amount of waste in each of the varieties from Florida was less than in potatoes from other states on the market during this period. This study showed one interesting thing as far as the Red Bliss and Pon tiac varieties from Florida are con cerned. Although the average grade defects for Pontiac was only about 70 percent and the average waste 60 per cent as much as in the Red Bliss variety, the average retail price for Pontiacs was .53 cents per pound less. The amount of Pontiacs sold in these stores was much less as shown by the fact that only 124 samples were collected for this variety in comparison with 318 samples of Red Bliss. From these data, it is impossible to say what caused this price differential. Type of Defects Found in Different Varieties The kind of damage scored as defects varied considerably by varieties. CutR and bruises accounted for 70 percent of the average grade defects in Red Bliss but only 53 percent in Pontiac and 20 percent in Sebago. In defects scored as injury, cuts and bruises made up 79 percent of the total in Red Bliss, 48 per cent in Pontiac and 42 percent in Sebago. Insect damage was the second most important grade defect in both the Red Bliss and Pontiac varieties being 12 and 17 percent, respectively. This defect amounted to only 2 percent in the Sebago variety. Greening and ex ternal discoloration due to sunburn, browning, sun scald and sticky scald amounted to 5 percent each for Red Bliss and 3 and 4 percent for the Pon tiac variety. These were the two most important defects scored in the Sebago variety. Greening amounted to 43 and external discoloration 30 percent of the total grade defects. External discolora tion also amounted to 42 percent of the defects scored in the injury classifica tion in this variety. Soft rot amounted to only six-tenths of 1 percent grade defect in the Sebago variety but less than one-tenth of 1 percent in both the Red Bliss and Pontiac varieties. The

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GREENE: POTATO QUALITY 139 three most important defects in the Red Bliss variety were cuts and bruises, in sect damage and external discoloration; in Pontiac, cuts and bruises, insect dam age and second growth; and in Sebago, greening, external discoloration and cuts and bruises. These three defects made up 87, 78 and 93 percent, respec tively, of the total grade defect scored in each of these varieties. Factors Affecting Defects The inspections of samples collected in retail stores and also the previous study of causes of losses in handling potatoes show that cuts and bruises is a major defect affecting the quality of potatoes from Florida, especially the red varieties. Cuts and bruises not only affect appear ance and result in a loss to consumers, they also are potential points of infection in which certain diseases such as soft rot may develop if the potatoes are subjected to conditions favorable for their develop ment. Work on the project "Spoilage in Marketing Early Irish Potatoes" showed that soft rot usually developed only in those shipments that traveled warm and contained a large amount of cut and bruised material unless it was a second ary infection following such things as blackleg, bacterial wilt and blight. At least half or more of the cuts and bruises in potatoes in retail stores occur after they leave the shipping points in transporting them to market and hand ling in the terminal market and retail store. The increase in damage after leaving the shipping point is not subject to the control of the producer or shipper. However, it does not cause a loss to the producer in shipping to market as may be the case if a lot of cut and bruised material is present when they leave the shipping point. Rough handling of pota toes should be avoided at all times. They should be dug carefully and handled with equipment that protects them from cuts and bruises. This may involve removing parts of the shakers, using rub. ber padding or rubber coated chains on the diggers, running the diggers more slowly and deeper, and using rubber coated picking baskets. The use of pad ding on graders and trucks, avoidance of dumping directly on wire chains, elimina tion of long drops in the grading equip ment, padding of unavoidable drops, care ful handling into padded bins or racks and careful operation of the washing and drying equipment will help in reducing damage. The second most important defect in potatoes from Dade county was insect damage. Approved control measures for insects and diseases should be practiced to eliminate as far as possible defects or losses due to these pests. The capacity of the graders for removing defects dur ing the grading process is limited so, if certain defects are reduced, more atten tion can be given to the removal of other defects. Greening was the most important de fect in potatoes of the Sebago variety. As is the case for cuts and bruises, the amount of greening increases after the potatoes leave the shipping point. Pota toes should be handled so as to move them through the market and to the con sumer without too much delay and they should be stored so as not to expose them to direct light. Browning, sunburn, sun scald and sticky scald spots was the second most important grade defect in the Sebago variety . These defects also caused 41 percent of the damage in the injury classification. This damage was due to exposing the potatoes to weather condi tions favorable for developing these con ditions. Producers are aware of the damage caused by leaving potatoes ex posed on the ground for even short pe riods on hot days, and they are usually picked up promptly after digging. How ever, considerable damage will occur to potatoes in field containers, especially

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140 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 field bags, if they are left in the field for long periods under certain weather condi tions. In the Hastings area, potatoes are quite often left in the field several hours before hauling. In the study in 1949, one-third of the test lots studied in this area remained in the field five hours or longer between picking up and hauling. Browning and scald spots are caused by rapid drying of the skinned areas of the potato. The rate of drying is de termined by the amount of evaporation which varies throughout the day accord ing to weather conditions. High tempera ture, low relative humidity, high wind velocity and intense sunlight all tend to increase the rate of drying and thus in crease the amount of injury caused dur ing a given period of exposure. In the study of losses in handling potatoes, rec ords were obtained for each test lot showing when the potatoes were dug, how long they were exposed in the field before and after picking up and the rate of evaporation during each hour they were exposed. These data and also work with exposed samples in 1948 showed that the breaking point between serious injury and slight to no injury from ex posure for the Sebago variety is an evaporation rate of about 3.0 c.c. per hour. The amount of damage to pota toes exposed to a rate of evaporation this much or higher increases with the length of exposure. The greatest increase is in sun scald. Although very little scald spots occur at a rate of evaporation less than 3.0 c.c . per hour, browning will de velop and the amount increases with the length of exposure. On most days ing the potato harvest in Florida, evapo ration rates of 3.0 c.c. per hour or greater occur between 9 :00 A.M. and 4 :00 P.M. and often even later in the afternoon. Producers should plan not to allow pota toes to remain in the field for more than one hour during this period if they want to be reasonably sure of not ' having in jury from exposure. In some cases this will necessitate a closer co-ordination be tween digging and the operation of the packinghouses, for the rate of digging must be regulated more in line with the capacity of the houses to grade and pack potatoes. Damage from exposure not only results in physical losses but it affects the appearance of the potatoes and the consumer acceptance of the product. Most of the potatoes grown in Florida are packed in fairly modern packing houses. However, abuses at times are allowed to creep into their operation which tends to reduce the effectiveness of grading and the preparation of the product. Too often, major attention is placed on volume even though this re sults in practices that reduce quality and increase losses. Crowding the wash ing and grading equipment beyond its intended capacity results in an increase in mechanical damage, inadequate drying and partially cleaned potatoes of poor appearance. Poor drying of the Sebago variety often causes lenticel infection that gives the potato a dark, spotty, undesirable appearance. Slowing down the speed of grading and packing may result in some increase in cost but this should be offset by an improvement in quality and appearance of the pro_duct. Summary Early Irish potatoes are highly perish able and need more careful treatment during harvesting and marketing than they often receive . The full cooperation of all agencies from the grower to the clerk in the retail store is needed to de liver potatoes to the consumer that are relatively free from defects. Potatoes from Florida compete with old potatoes and also with new potatoes from other producing areas. They are a low unit value farm product and the price of Flor ida potatoes is affected by both the sup ply of old and new potatoes. The amount of additional expense that can be in

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BUHGIS : ALUMINUM FOIL MULCH 141 curred in improving the handling pro cedure is limited. In many cases both growers and shippers must develop a keener appreciation of the factors neces sary to produce quality and cooperate in following those practices. Often a better job could be done without increasing cost simply by paying more attention to the factors that affect quality. Addi tional research may also aid in develop ing more efficient methods of handling potatoes. MULCHING VEGETABLE CROPS WITH ALUMINUM FOIL DONALD S. BURGIS Florida Agricultural Experiment Stations Vegetable Crops Laboratory Bradenton The practice of mulching plants is of very ancient origin and gardeners today employ the same techniques as were used several hundred years ago. Mulching consists of covering the soil around the base of a plant with a layer of undecom posed organic material which may con sist of dry leaves, straw, weeds, or some other matter which is more or less refuse by nature. The use of mulches is limited mostly by their costliness when employed on a large scale. Good mulch material is bulky and thus difficult to gather, trans port, and distribute. To be effective the mulch must be four to six inches deep which, of course, means that it takes a tremendous amount of material for areas of any size. The advantages of mulching are: (1) conservation of moisture, (2) reduction of soil temperature, (3) dis couragement of weed growth, and ( 4) a resulting cleanliness of the crop. The disadvantages are: (1) the encourage ment of the growth of soil fungi detri mental to the plant, (2) introduction of weed seeds, (3) increased soil acidity, (4) loss of nitrogen which accompanies the decomposition of some mulch ma terials, and (5) the fire hazard. The development of aluminum foils1, 1 Reynolds Al;,minum Co., Richmond, Va . obtainable in varying weights and widths, has brought to light a brand new category as regards mulch material. Here we have a material which is light in weight, easy to handle, impermeable to moisture, and reflective to heat rays. The foil also has a salvage value when gathered up, baled and returned to the company. In the winter season of 1949-50 a pre liminary experiment was initiated at the Vegetable Crops Laboratory to determine to what extent aluminum foil might be used as a mulch for vegetable crops. It was expected that the mulch might prove beneficial in the following ways: (1) by reducing soil and surface temperatures, increase the length of the harvesting season for some cold season crops that break down rapidly in warm spring weather, (2) increase yields in general by conserving fertilizer and moisture. These first tests involved plots mulched with aluminum foil compared to non mulched plots. The mulched plots were then divided as to fumigation for root knot control and fertilizer applied at 3 different rates with 2 side dress treat ments. The EDB (Ethylene Dibromide 10 percent) was applied at the rate of 10 gallons per acre. The fertilizer, a 4-7-5, 25 percent organic, was applied as follows: (1) 750 lbs. per acre in the bed one week prior to setting + 750 lbs. as a side dressing one month after set ting, (2) 1500 lbs. all at once in the bed one week before setting, (3) 1500 lbs.

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142 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 in the bed + 750 lbs. as a side dressing and, (4) 3000 pounds all at once in the bed one week prior to setting. Five different vegetables were planted: strawberries, onions, broccoli, lettuce and carrots. The strawberry experiment, using both Missionary and Klonmore varieties, was interesting in that the fumigated plots showed 68 percent yield increase in favor of foil and approximately 25 per cent in favor of the higher rates of fer tilization (See Table 1). Neither of these increases was statistically signifi cant however. The unfumigated plots were a total failure and to date the cause TABLE 1 STHA WHERRIES-SHOWING YIELD OF FERTILIZER. AND FOIL PLOTS (GMS.). Fertilizer 3000 1500 1500 + 750 750 + 750 Total Foil 1964 1300 1727 1924 6463 No Foil 1540 840 1180 841 4401 Total 3504 2140 2455 2765 10864 of this has not been determined. Root as to confound the results of the .comknot galls were not present and parasitic nematode numbers as determined by Dr. J. R. Christie, Senior Nematologist, U.S.D.A., did not indicate that plant stimulation could be due wholly to the control of these pests. With Texas Grano onions, fumigation was superior to no fumigation, but in this case the difference was not so great parison of other factors. Foil gave an increase in yield of 315 percent which was related directly to the conservation of fertilizer (See Table 2). With onions some of the significance attributed to the foil for the conserva tion of fertilizer may be due in part to the reduction of soil temperature as a result of the reflectivity of the_ foil to TABLE 2 TEXAS GRANO ONIONS-SHOWING FERTILIZER AND FOIL PLOTS (WEIGHT IN GMS. 10 RANDOM PLANTS) Fertilizer 3000 1500 1500 + 750 750 + 750 Fumigated Foil 2160 3160 1300 345 No Foil 490 560 320 75 Sum 1750 1920 1620 420 Non Fumigated Foil 615 365 745 163 No Foil 70 78 65 95 Sum 685 443 810 258 ~oth Foil 1875 1725 2045 508 No Foil 560 638 385 170 Sum 2435 2363 2430 678 A difference of 905 is necessary for significance between foil and non-foil covered plots. A difference of 639 is necessary for significance between fertilizer rates, Sum 4265 1445 5710 1888 308 2196 6153 1753 7906

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BUHGIS : ALUMI N UM FO IL MULCH 14 3 s un light . Thi s i s one of the major c l aims made by other workers but it cou ld not be substantiated in t h e present test be cause the nece ssa r y eq uipmen t fo r mak ing the det e rmination s was not avai labl e. With q ro cco li ( Early Sprouting) foil incr ease d yields about 45 percent. The incr ease d y ields seems certainly to be due to the conservation of fertilizer although s u c h an assumption is not va li d TABLE 3 BROCCOLI SHOW I G FOIL PLOTS ( TOTAL WEIGHTS 1N CMS . ). Fertili ze r 3000 1 500 1500 + 750 750 + 750 Sum Foil 343 7 2797 5272 2470 13976 No Foil 2562 1 85 1 2399 930 77 42 Sum 5999 4648 7671 3400 21718 Diff e r e n ce of 4674 for s i g nifican ce b e tw ee n fo il and no foi l. bec a use analysis of the results ( Table 3 ) doe s not s h ow the difference to be s ig nificant . The lettu ce ( Great Lakes ) te s t fai l ed be ca u se of a s lime rot which attacked the plants as they approached maturity. Thi s rot was particu l arly bad on p l ot s covered with foil. With carrots ( Imperator ) the foil cove red plots produced s ignificantly ; ' \ --~--~ ., ,, }, ... . . ,: [t; /~ .. ":_., , , , ("' Fu mig at e d strawberry p l ots which received 3 000 pounds of f erti l izer all in the bed one week prior to setting . Pla nts l e ft not mu l checl ; on right mulche d wi th aluminwni foil.

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144 F LORJDA STATE HORTICULTURAL SOCIETY , 1950 earlier and larger carrots than the non foil covered plots. All plots were infested with root knot. From the results to date the beneficial effects of foil mulch on crop yield as shown here are probably the result of the interaction of the following phenomena: ( 1 ) conservation of moisture, ( 2 ) pro tection of solub le fertilizer salts against leaching, ( 3 ) reduction of soil tempera tures, and, ( 4 ) the control of weeds. TRANSITORY EFFECTS OF 2,4-D ON THE WATERMELON PLANT WHEN ABSORBED THROUGH THE ROOTS CLYDE C. HELMS, JR. AND G. K. PARRIS Florida Agricult ura l E xperiment Statio ns Wcit erme lo n cind Grape I nvesti gatio ns Leib oratory Leesburg Watermelon seeds were planted in Norfolk sand at Whitney, Florida, on the farm of this laborator y on July 5, 1950. The purpose o f so late a pl a nting of one acre of melon s was to obtain F , seed from melon crosses made in the s pring crop . We s peed up our watermelon breeding F ig . 1-A. Top view of normal water1ne lon plant . Co11 i pare with Fig . 1-B. program by this method , which ha s been employed in previou s years. The seeds germinated rapidly and had emerged by Jul y 11. By July 26 man y weeds were competing with the young melon plant s . It was decided to elimi n a te the weeds, mostl y Florida Pusley ( R ich a rdia sc ab m) and volunteer hair y indigo (In d i go/ em hirsuta), by the appli ca tion of 2,4-D. Each melon hill wa s covered with a papier-mache' meat tra y to protect the melon plants from the weed-killer. The melon seedlings were s mall enough t o permit this without physical damage b y pressure. An amine 2,4-D s pray was app li ed to the soil with F ig . 2 -A . S ide view of no1mal water1nel on plant . Compare wit h Fig. 2-B.

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HELMS AND PARRIS: EFFECTS OF 2 , 4-D ON WATERMELON 145 a 3-gallon sprayer, calibrated to deliver 60 gallons of solution per acre, at 40 to 50 pounds pressure. The rate of appli cation was approximately pound free acid equivalent per acre. Care was taken to avoid excessive spray application near, or on, the paper cover over the melon plants. In a few cases, where the 2,4-D spray accidentally fell on melon foliage, mJury occurred. The papier-mache' covers were removed soon after the soil was sprayed. By July 31 it was apparent that excel lent control of the Florida Pusley was being obtained. Other than a few acci dentally injured melon plants mentioned above, all seedlings appeared normal and growing. From July 26 to July 31 slight ly Jess than one-third of an inch of rain fell on the treated plot. On August 2, there fell 2.58 inches of rain, on August 5 there fell 0.21 inches, and on August 6 there fell 0.34 inches. Two showers of less than one-tenth of an inch each fell on August 9 and 10, and on August 11 there was measured 1.21 inches. From date of application of the 2,4-D (July 26 ) until August 11, a total of 17 days , the Fig. 1-B. Top view of 2,4-D affected waterrnelon plant. Cornpare with Fig. 1-A. treated plot received more than 4 and one-half inches of rain. The soil being sandy, the rain penetrated quickly and deeply. The maximum air temperature during this period varied from 77 to 92 F., and the minimum from 69 to 76 F. Definite abnormal growth characteris tics appeared by August 3 on the melon plants in areas where the soil was sprayed. Melon plants on adjacent un: s prayed soil appeared normal. The Flor ida Pusley was now dead. Symptoms of 2,4-D injury to the melon plants included dwarfing and thickening of the first true leaves, a prominent whitish venation, a curling under of the leaf margins, and definite elongation of the petioles of affected leaves. Less noticeable symp toms included a pimpling of the surface of otherwise normal leaves. Typical in jured plant s are shown in Figure s 1 and 2 . Stunted plants survived and in fact grew more rapidly than expected, coming out of the shock condition by August 25. By September 1 it was clear that the plants would bear flowers and fruit norFig. 2-B. Side view of 2,4-D affected watermelon plant. Cornpare with Fig. 2-A.

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146 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 mally, and this has proved to be the case. It is concluded that the symptoms shown by the watermelon plants were brought about by varying amounts nf 2,4-D absorbed by the roots. The absence of stem and petiole curvatures, the norm when surface application of 2,4-D is made to a plant, confirms this diagnosis. Further, the extreme care taken in ap plication obviated contact of the weed killer with the foliage or stems of the melon seedlings. We are presenting this paper to show that small quantities of 2,4-D can be absorbed by watermelon plants from the soil through the root-systems, when weed-killers are applied with the plants in situ. The same or a similar response may occur when the soil is sprayed to eradicate weeds, and melon seeds planted later. However, the injuries described are of a transitory nature only, for the affected plants grew out of the condition and flowered and fruited normally. PROCESSING SECTION COMPARISON OF PLATING MEDIA USED FOR THE ESTIMATION OF MICROORGANISMS IN CITRUS JUICES 3 E. C. HILL 1 AND L. W. FAVILLE 2 Citrus Experiment Station Lake Alfred The production of frozen concentrated citrus juices requires a certain amount of routine bacteriological control work, most of which is concerned with the com mon plate count. The significance of a "total" count on any particular sample of concentrate is extremely doubtful since, in many instances, it does not reflect the quality of the product nor the cleanliness of the plant. However, plate counts made at frequent intervals over extend ed periods of time may give the plant operator information which will allow him to predict how long he can continue 1 Research Fellow, Florida Citrus Commission. . Bacteriologi~t, Citrus Experiment Station. Cooperative research by the Florida Citrus Experi ment Station and the Florida Citrus Commission. to operate before he can expect a build up of contamination in the equipment. The desirability of standardizing microbiological techniques is one of the many problems which will eventually confront the manufacturers of frozen citrus concentrates. As might be ex pected in the case of such a recently de veloped industry, several recommenda tions have been made with regard to the proper techniques and media to be used in the bacteriological analysis of these products. It is the purpose of this report, there fore, to compare the efficiencies of vari ous plating media which have been recommended. On the basis of experience resulting from the use of separate media for the determination of total counts and yeast and mold counts in concentrat . ed citrus juices, it is evident that the microflora

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HILL AND FAVILLE: PLATING MEDIA 147 of these products can range from pre dominantly yeast to predominantly bac teria. Consequently any medium which may be selected as a standard medium for the determination of a total count in citrus products should be capable of sup porting good growth of both bacteria and yeasts. Experimental Representative ratios of bacteria and yeasts were obtained by the use of washed suspensions of cells. For each run 10 different bacteria were isolated from frozen orange concentrate and grown on dextrose agar slants. After 24 hours incubation of 30 C. the growth was washed from the surface of these slants with 5 ml. aliquots of a sterile molar phosphate buffer (pH 7.0) and combined. A composite yeast suspen sion was obtained in a similar manner. These suspensions were then plated on dextrose agar and adjusted by diluting with sterile buffer so that each suspen sion contained approximately equal num bers of cells per ml. These suspensions were then mixed in ratios varying from all bacteria to all yeasts and appropriate dilutions of all ratios plated in duplicate on each of ten different plating media. The composition of the plating media included in this investigation were as follows: Lindegren Agar No. 1: 4.0 percent dextrose, 0.5 percent yeast extract, 0.35 percent proteose peptone, 0.2 percent KH,PO,, 0.1 percent MgSO,, and 2.0 per cent agar. To each liter of this medium 7 ml. of a 50 percent medium lactate solution was added. Lindegren Agar No. 2: Similar to the above medium but modified to contain 2.0 percent dextrose and 0.1 percent KH,PO, instead of the 4.0 percent and 0.2 percent respectively which were pres ent in the original medium. Tomato Serum Agar: 1.0 percent tryptone, 0.3 percent beef extract, . 0.2 percent K.HPO,, 0.3 percent yeast ex tract, 0.5 percent dextrose, and 1 . . 7 per cent agar. Two hundred ml. of a clear tomato serum was added to each liter of medium. Dextrose Tryptone-Yeast Extract Agar: 1.0 percent tryptone, 0.5 percent yeast extract, 0.3 percent beef extract, 0.1 percent glucose, 0.1 percent K,HPO,, and 1.5 percent agar. The remaining six media (Table 1) used were prepared from dehydrated Difeo media. Results and Discussion The results in Table 1 represent the averages of four separate experiments. Thus the averages of the five . ratios TABLE l. COMPARISON OF PLATING MEDIA AT DIFFERENT BACTERIA: YEAST RATIOS Bacteria: Yeast Ratios Medium pH 4:0 3:1 2:2 1:3 0:4 Average Tryptone-glucose-extract agar (Difeo) 7.0 34.3 1 43.5 42.0 37.8 40.3 39.6 Potato dextrose agar (Difeo) 3.5 0 5.0 16.0 25.0 30.0 15.2 Lindegren yeast agar No. 2 5.8 34.0 36.8 42.5 35.5 46.3 39.0 Tomato serum agar 6.5 35.8 42.3 45.5 40.0 42.5 41.2 Sabouraud dextrose agar (Difeo) 5.6 22.5 . 33.0 40.5 45.5 39.8 36.3 Dextrose-tryptone-yeast extract agar 7.0 40.3 41.8 40.5 43.0 42.3 41.6 Dextrose-tryptone agar (Difeo) 6.7 35.3 43.0 42.5 39.3 40.3 .40.1 Dextrose agar (Difeo) 7.3 35.3 43.0 49.0 43.3 41.7 42.7 Nutrient agar (Difeo) 6.8 37.0 32.8 31.3 38.8 37.0 35.4 Lindegreri yeast agar No. 1 5.8 24.5 35.8 38.0 42 . . 8 39.3 36.1 1 AU : . counts . X . 10'.

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148 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 which are given for each medium actually represent the averages of 20 separate observations. The least significant mean difference between the averages of 20 observations, as determined by statistical methods, was TABLE 2. Comparison of Dextros e Broth and a Liquid Yeast Medium with Regard to Their Abilities to Support Bacterial Growth. Culture Dextrose Lindegren No. Broth (pH7 . 3) Broth ( pH 5.8) M-4 73 1 100 M-5 77 86 M-6 82 93 M-9 97 100 M-10 68 90 M-11 73 95 M-13 70 93 M-14 97 98 M-17 71 94 M-20 82 82 M-21 91 86 M-22 65 91 M-23 90 90 M-24 69 90 M-25 84 99 M-26 70 98 M-27 91 95 M-28 71 95 M-29 68 98 M-30 86 97 M-32 69 95 M-33 75 95 M-34 56 76 M-36 73 95 M-42 89 95 M-43 69 67 M-56 75 95 M-65 100 100 M-66 60 88 M-73 59 66 M-75 99 95 M-92 62 72 M-99 1 71 Average 77 90 1 Figure r e presents p e rcentage of light transmitt e d through culture based on 100 percent light tra11smis sion through an uninoculated tub e of the s a me medium. 7.14. From an examination of this data it is evident, that, of the ten media tested, only acidified potato dextrose agar and nutrient agar yield results signifi cantly lqwer than the best medium which, according to the conditions of this ex periment, wa s Bacto-dextrose agar. Potato dextrose agar acidified to pH 3.5 finds common usages as a selective medium for the enumeration of yeasts and molds, since at this low pH it will not support bacterial growth. This medium, while not suitable as a medium for total counts, would be valuable for determining the relative proportions of bacteria and yeasts in citrus juices when used in con junction with a medium which would grow both yeasts and bacteria. On the other hand, media having pH values considerably below the optimum for most bacteria have gained wide usage in the frozen concentrate industry. Sabouraud dextrose agar and Lindegren's yeast medium, with pH values of 5.6 and 5.8 respectively, are recommended for the isolation and cultivation of yeasts and molds. Although the addition of an in hibitory substance such as copper sulfate is required to completely suppress bac terial growth, the medium alone will in hibit many bacteria to varying degrees. This inability of a medium of this type to support good growth of many species of bacteria is clearly illustrated in Table 2. Thirty-three bacterial isolates orig inating from frqzen orange concentrate were grown in broth counterparts of dex trose agar and the modified Lindegren agar which were included in Table 1. Following a 48 hours incubation period at 30 C. the degree of growth in these tubes was measured turbidimetrically in a Fisher electrophotometer. The value s given in Table 2 represent the percent age of light transmitted by the cultures based on 100 percent light transmission through the uninoculated medium. The superiority of the dextrose broth over the yeast medium is shown by the values of

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HILL AND FAVILLE: PLATING MEDIA 149 TABLE 3. COMPARISON OF PLATING l\IEDIA AT DIFFERENT BACTERIA: YEAST RATIOS Medium Dextrose agar (Difeo) Dextrose-tryptone agar (Difeo) Tryptone-glucose extract agar (Difeo) Dextrose-tryptone yeast extract agar Sabouraud dextrose agar (Difeo) Lindegren yeast agar No. 1 Malt agar (Difeo) Potato dextrose agar (Difeo) 1 All counts X 10'. 77 and 90 respectively for the averages of the 33 cultures. Seventeen of the total number of cultures gave turbidity readings of 95 or higher in the yeast medium indicating very slight growth of these organisms. The data presented in Table 3 repre sent a preliminary run which was not included in Table 1, since at the time of this particular experiment, several of the media listed in Table 1 had not been in troduced into the frozen concentrate in dustry. The results of this run are in included at this point, however, to show the type of results which might be ex pected if the greater majority of the bacteria present in a juice were strains which did not grow well in a low-pH medium. During the isolation of the bacteria used in this run no attempt was made to isolate organisms of this type. Comparable results were obtained with the four media whose pH values ranged from 6.7 to 7.3. Sabouraud dextrose agar and the Lindegren yeast medium, how ever, gave satisfactory results only when Bacteria: Yeast Ratios pH 4:0 3:1 2:2 1:3 0:4 Averag es 7.3 580 1 330 390 290 40 326 6.7 560 420 440 270 22 342 7.0 590 610 420 250 40 382 7.0 540 560 500 260 23 417 5.6 4.1 14 36 17 40 22.2 5.8 4.3 15 29 15 33 19.3 3.5 0 0.6 1.8 2.5 3.4 1.7 3.5 0 1.0 1.8 3.0 3.6 1.9 a suspension composed entirely of yeasts was plated. Malt agar and potato dex trose agar, both acidified to a pH of 3.5, were unsatisfactory at all ratios in this particular instance. Summary From these results it is apparent that under normal conditions any of the media included in Table 1, with the exception of acidified potato dextrose agar and possibly nutrient agar, could be employed satisfactorily as a medium for obtaining a total microorganism count in citrus juices. However, the limitations of any of these media should be clearly understood. No . single medium will support the growth of all types of microorganims equally well, and the possibility aiWays exists that abnormally high counts resulting from a build-up of contamination in the plant equipment might not be reflected in the counts obtained during routine ex aminations if a single plating medium is used.

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150 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 RELATIVE EFFICIENCIES OF SEVERAL LIQUID PRESUMPTIVE MEDIA USED IN THE MICROBIOLOGICAL EXAMINATION OF CITRUS JUICES 3 L. W. FAVILLE 1 AND E. C. HILL 2 Citrus Experiment Station Lake Alfred Introduction According to the definition given in the latest edition of Standard Methods of Water Analysis (2), the coliform group of organisms should be considered as including "all aerobic and facultative anaerobic, Gram-negative, nonsporeform ing bacilli which ferment lactose with gas formation." Although the presence and estimation of the number of these organisms in water has become an in tegral part of the bacteriological pro cedure for judging the quality of water, the significance of their presence in citrus and other food products is not . so clearly understood. Since Wolford (3) found organisms resembling Escherichia coli in citrus juices, it is probable that further work will be done in an effort to deter mine the incidence and significance of these organisms in citrus juices. It is essential, therefore, that a standard en richment medium for the detection of these organisms in citrus juices be adopt ed for use in future investigations. For tunately, the citrus industry has the advantage of knowledge gained through the almost countless numbers of investi gations which were directed toward the selection of a standard presumptive medium for the examination of water. During the years following 1923, at which time the Committee on Standard Methods of the American Public Health 1 Bacteriologist, Citrus Exp e riment Station. 2 Research Fellow, Florida Citrus Commission, Cooperative research by the Florida Citrus Com mission and the Florida Citrus Experiment Station. Association adopted a 0 . 5 percent lactose broth a s the standard presumptive medium, many enrichment media have been proposed to replace it. Since the ideal medium would be one which would prove favorable to growth of the coliform group and unfavorable . to all other or ganisms, these media have been thor oughly evaluated from this viewpoint. Before any medium will be recommended to replace standard lactose broth, it must b e shown that the medium in question will give fewer gas-positive presumptive tests than lactose broth and, at the same time, yield a higher percentage of coli form isolations. Thus far, only one medium, lauryl tryptose broth, has satis fied these requirements and this only as a preliminary enrichment medium for certain types of water . For obvious reasons, the adoption of a routine medium for the detection of coli forms in citrus products should require the same careful thought. Logically the nature of the product would suggest that methods suitable for the analysis of water would not necessarily be the most satisfactory in this case. In order to obtain a sufficient sample for analysis, a relatively laige amount of sugars other than lactose must be added to the medium. For example, ac cording to the procedure recommended by Beisel and Troy (1) for using the Vaughn-Levine ~oric acid medium, 25 ml. of a 42 Brix concentrate was recon stituted to 100 ml. with 75 ml. of a con centrated medium. In this case, the re sulting medium contained, in addition to the customary 0.5 percent lactose, at least 5 percent of sucrose and invert sugars. Similarly, if only 1 ml. of a

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FAVILLE AND HILL: PRESUMPTIVE MEDIA 151 reconstituted concentrate is added to 9 ml. of medium, there is still present in the final medium between 0.5 and 1.0 percent of these sugars. Although the first presumptive medium that was adopted by the Committee on Standard Methods contained 1 percent glucose, it was later shown that many bacteria of little or no sanitary significance were able to ferment this sugar and the more selective lactose was substituted. Also the original concentration of 1 percent was lowered to 0.5 percent when it was shown that E. coli might be killed by the acidity produced from the higher concen tration. For the purpose of selecting an en richment medium for the detection of coliform organisms in citrus juices, the picture is further complicated by the fact that the juices usually contain rela tively large numbers of yeasts, many of which are capable of fermenting sucrose or hexoses with the formation of visible gas. The purpose of this work was to eva luate several possible enrichment media on the basis of their ability to (1) Suppress the growth of yeasts, par ticularly those gas-producing species, and (2) Allow the detection of coliform organisms even though they are present in relatively small numbers. Experimental The necessity for this study was pointed out by the results of a preliminary survey which was carried out during the 1949-50 season. During this survey 48 samples of 42 Brix orange concentrate, including 12 samples which were obtained from Wolford, were tested using standard lactose broth, brilliant green lactose bile and the Vaughn-Levine boric acid medium. For purposes of comparison and inoculum to medium ratio suggested by Beisel and . Troy was used for all media. Similarly, all tests were run in duplicate, one set be ing incubated at the customary 37 C. which is recognized by Standard Methods while the other was incubated at 43 C. , the temperature recommended for the boric acid medium. All presumptive tests showing any amount of gas with in 48 hours were confirmed by the usual methods. Results of this survey are presented in Table 1. On the basis of this short survey it appears that standard lactose broth, al though yielding a greater percentage of false positive reactions than either of the other media, is a more efficient enrich ment medium for the isolation of these organisms. It is also apparent that in creasing the incubation temperature from 37 C. to 43 C. decreases the num ber of positive presumptive tests. More significant, however, is the fact that the percentage of positive confirmations was also decreased at the higher temperature. The complete lack of confirmation in the case of the boric acid medium should not TABLE 1. COMPARISON OF LACTOSE BROTH, VAUGHN-LEVINE BORIC ACID BROTH AND BRILLIANT GREEN LACTOSE BILE AS ENRICIUIENT MEDIA FOR COLIFORM ORGANJSI\IS IN 42 BRIX . ORANGE CONCENTRATE. Standard Vaughn-Levine Brilliant Lactos e Boric Acid Green Lactos e Broth Medium Bile s1•c. 43c. a1c. 43c. a1c. 43c. Total number of samples 48 48 48 48 48 48 Number of positive presumptive tests 48 33 34 14 37 9 Number of positive tests confirmed 8 4 0 0 3 2 Percentage of total tests confirming 16.7 8.3 0 0 6.2 4.2

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152 FLO IUD A STATE llOHTICUL TUB.AL SOCIETY, HJ50 be construed to mean that this medium inhibits these particular organisms be cause such is not the case. All organisms which were isolated from either of the other two media and which resembled E. coli to any degree on eosin methylene blue agar were capable of producing gas in the boric acid medium at 43 C. when grown in pure culture. The fact that these organisms did not show up in the boric acid medium under the conditions of this experiment does suggest, however, that more work should be done before this or any medium is selected as a standard enrichment medium for the examination of citrus juices. The data in Tables 2 and 3 illustrate the relative merits of several possible media for separating yeasts and coli forms. Fifty strains of yeasts isolated from orange juice and 16 strains of E. coli obtained from various state health laboratories were used in this study. Standard lactose broth, brilliant green bile 2 percent, lauryl tryptose broth and the boric acid medium were compared. Glucose in an amount of 0.5 percent was added to each of the media in order to provide a fermentable sugar other than lactose. This was done in an effort to more nearly simulate conditions obtained when concentrate is added to a presump tive medium. As shown in Table 2, 12 of a total of 50 yeast strains were capable of fer menting sugars in the lactose broth to gas when incubated at 37 C. for a period of 48 hours. Brilliant green lactose bile, while inhibiting some of the non-gas producing yeasts, did not inhibit the gas formers over a period of 48 hours. In the case of lauryl tryptose broth, however, only 3 of the 12 strains produced gas TABLE 2. GROWTH AND GAS PRODUCTION BY STRAINS OF YEASTS AND ESCHERICHIA COLI IN SEVERAL LIQUID PRESUMPTIVE MEDIA AT 37 C. YEASTS Standard Lactose Brilliant Green Laury! Tryptose Vaughn-Levine Broth Lactose Bile Broth Boric Acid Broth Hours Incubation 24 48 24 48 24 48 24 48 Total strains 50 50 50 50 50 50 50 50 Number growing 36 42 23 25 22 23 6 6 Percent growing 72.0 84.0 46.0 50.0 44.0 46.0 12.0 12.0 Number gasing 10 12 3 12 0 3 0 0 Percent gasing 20.0 24.0 6.0 24.0 0 6.0 0 0 E.COLI Standard Lactose Brilliant Green Laury! Tryptose Vaughn-Levine Broth Lactose Bile Broth Boric Acid Broth Hours Incubation 24 48 24 48 24 48 24 48 Total strains t'6 , : , . 16 . > 16 16 16 16 16 16 Number growing 16 16 16 16 16 16 11 16 Percent growing 100.0 100.0 100.0 100.0 100.0 100.0 68.8 100.0 Number gasing 16 16 16 16 16 16 11 14 Percent gasing 100.0 100.0 . 100.0 100.0 100.0 100.0 68.8 87.5

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FAVILLE AND HILL: PRESUMPTIVE ~IEDIA 153 TABLE 3. GROWTH AND GAS PRODUCTION BY STRAINS OF YEASTS AND ESCHERICHIA COLI IN SEVERAL LIQUID PRESU!IIPTIVE MEDIA AT 43 C. YEASTS Standard Lactose Brilliant Green Laury! Tryptosc Vaughn-Levine Broth Lactose Bile Broth Boric Acid Broth Hours Incubation 24 48 24 48 24 48 24 ,18 Total strains 50 50 50 50 50 . 50 50 50 Number growing 13 13 3 3 8 10 1 1 Percent growing 26.0 26.0 6.0 6.0 16.0 20.0 2.0 2.0 Number gasing 0 9 0 0 0 0 0 0 Percent gasing 0 18.0 0 0 0 0 0 0 E.COLI Standard Lactose Broth Brilliant Green Lactose Bile Laury! Tryptosc Broth Vaughn-Levine Boric Acid Broth Hours Incubation 24 48 24 Total strains 16 16 16 Number growing 16 16 16 Percent growing 100.0 100.0 100.0 Number gasing 10 12 5 Percent gasing 62.5 75.0 31.25 in 48 hours while the boric acid medium completely inhibited all but 6 of the 50 strains and none of these were gas-pro ducers. On the other hand, all 16 strains of E. coli grew and produced gas within 24 hours at 37C. in all media except the boric acid medium. In this medium, 11 of the 16 strains grew within 24 hours and 14 produced gas within 48 hours. As shown in Table 3, completely dif ferent results were obtained at an incu bation temperature of 43C. with only lactose supporting gas production by yeasts at this temperature. However, the advantage of increased inhibition of yeasts at the higher temperature is mini mized by a corresponding inhibition of E. coli in all of the media except the Vaughn-Levine medium. Discussion On the basis of these results, none of the four media which were compared are completely satisfactory for the pur48 24 48 24 48 16 16 16 16 16 16 16 16 16 16 100.0 100.0 100.0 100.0 100.0 7 14 14 14 14 43.75 87.5 87.5 87.5 87.5 pose of eliminating false positive pre sumptive tests and for the detection of the presence of coliforms. It is also probable that in the majority of in stances citrus juices will contain as many or more yeasts and fewer coli forms than were used for inocula in these experiments. The most important criterion for evaluating a presumptive medium is its ability to support the growth of coli form organisms as well as inhibit other organisms. Therefore any medium recommended as a standard enrichment medium for citrus juices should first be carefully compared with a medium known to be capable of detecting the presence of coliforms. Similarly, it is important that such a comparison be made under natural conditions, since the use of pure cultures ignores such factors as the possible presence in cit rus juices of substances which are slightly toxic to coliform organisms.

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15 4 FLOHIDA STATE HOHTICULTUHAL SOCIETY , Hl50 The presence of such substances might be particularly significant in the case of media containing inhibitors in con centrations slightly below a level at which coliforms themselves are affected. These factors, in combination with an incubation temperature above the opti mum for coliforms, could explain the inability of selective media to detect these organisms in some instances. LITERATURE CITED 1. }}EISEL , C. G. a nd V. S . TROY, l!l49 . Th e Vaughn-L e vin e boric a cid medium a s a s c re e ning pre s umptiv e t es t in th e examination of froz e n conc e ntr a t e d o rang e juice. Fruit Product s ]our, and Am e ,ic a n F o od Manufacture,. 28 ( 11) : 356-357 . 2. S-rANDARD METHODS O F WATER ANALYSI S . 1946. Standard Methods for the Examination of Water a n d S e wa ge. Ninth .Edition. Am e rican Public H e alth A ss ociation, New York. . 3. WOL F ORD , E. R. 1950. Bacteriological studi es on frozen oran ge juice stored at -lO'F. Food Technology . 4 ( 6) : 241-245. STORAGE CHANGES IN CITRUS MOLASSES R. HENDRICKSON 1 AND J. W. KESTERSON 2 Citrus Experiment Station Lake Alfred Introduction Citrus molasses, which has become a familiar livestock feed in Florida has been produ ced commercially for less than ten years. Its wide acceptance and increasing popularity warrant more complete understanding of its physical and chemical properties. Buyers of this carbohydrate concentrate are interested in obtaining further information re garding the product, storage changes, and the ramifications of microorgan isms associated with it. . Citrus molasses is . produced from the rinds . and pulp of citrus after the juice has been expressed. This :waste tesi due is chopped, limed, and pressed to yield a press liquor of 10 -14 Brix (percent soluble solids content by weight) which when concentrated to 72-75 Brix is the final molasses. Since citrus molasses can . be produced only during the processing season, the proGessor Js required to store millions of gallons to serve the year round needs 1 A s si s tant . Chemist, Citrus Experiment Station, Lake Alfr e d, , Florida . ; A s sociat e Chemist, Citrus Experiment . Station, Lake Allred, Florida. of cattlemen . Certain changes take place during storage and they are the subject of this report to industry. Before discussing storage changes in citrus molasses it might be well to ex amine Table 1 wherein the comparative analysis between this product and the common molasses obtained from sugar refining is presented . The average analysis for clarified citrus molasses represents samples made from several varieties of both grapefruit and orange. Clarified molasses refers to a product made from a clear press liquor. It is immediately noticeable that blackstrap is generally concentrated to a higher degree Brix, but has the disadvantage of having more than a proportionately higher ash content. Citrus molasses producers tend now to use 72 Brix as a minimum value with the average being maintained at a higher level! Sugar Losses and Instability Durjng Storage In storage,' citrus molasses has been found to slowly undergo both a physical and chemical transformation. Of para mount importance are the changes in sugar content which occur on storage. When ten samples of citrus molasses collected from ten commercial proces sors in January of 1948 were reana lyzed by the Lane-Eynon Volumetric procedure they were found to have lost

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IIENDHlCKSON AND KESTERSON: CITHUS l\IOLASSES 155 TABLE 1. COMPARATIVE DATA ON CITRUS AND BLACKSTRAP MOLASSES. Analysis Commercial 1 Clarified• Louisiana 1 Citrus Molasses Citrus Molasses Blackstrap Cuban• Blackslrap Brix 0 72.0 Sucrose % 19.6 Reducing Sugars 7o 22.9 Total Sugars % 43.5 Carbonate Ash % 4.7 Nitrogen % X 6.25 4.1 pH 5.0 1 Average of 36 samples. 2 Average of 16 samples (laboratory prepared). Fort (3). (See literature cited). an average of 1.7 percent total sugars per year of storage. Similarly, 13 sam ples collected in April of 1948 from 11 producers were found to have lost an average of 3.2 percent total sugars per year of storage. In contrast, however, are 13 samples of clarified citrus molasses made in the laboratory from different varieties of both grapefruit and orange that showed an average in crease of 0.4 percent total sugars per year of storage. These clarified citrus molasses samples precipitated consider73.1 26.1 24.9 52.4 3.0 3.6 5.9 90.7 30.1 26.4 68.0 10.8 1.6 6.7 87.2 37.3 16.6 55.8 10.9 2.1 5.5 able insoluble matter during storage and since only the supernatant liquid was analyzed it is understandable that the percent total sugars could increase even in the face of a slow deterioration of sugars during storage. Table 2 sum marizes these data showing maximum and minimum values as well as a com parison of sugar losses noticed in black strap during storage. Owen (6) investi gating the deterioration of blackstrap found that those samples having the highest total sugar values were most TABLE 2. COMPARISON OF SUGAR LOSSES DURING STORAGE OF CITRUS MOLASSES AS COMPARED WITH BLACKSTRAP. Description of Sample Commercial Citrus Molasses January 1948 Commercial Citrus Molasses April 1948 Clarified Citrus Molasses Blackstrap 2 , Factory No. 1 Blackstrap2, Factory No. 2 Blackstrap, 2 Factory No. 3 No. of Samples 10 13 13 1 1 1 1 Actually increased in percent total sugars ( See text) 1 Owen (6) Type of Value Average Maximum Minimum Average Maximum Minimum Average Maximum Minimum Change in Total Sugars per Year of Storage ( Calculated % ) -1.7 -3.4 -0.6 -3.2 -7.7 -1.3 +0.41 -1.3 +1.41 -6.3 -11.9 -11.3

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156 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 susceptible to actual deterioration in storage. Upon examining each of the 3 groups of citrus molasses samples pre viously mentioned, it was noted that within each group this same correlation generally held true for citrus molasses. The clarified samples of citrus molasses, however, did not deteriorate with the rapidity expected for their high total sugar content and is probably accounted for by the removal during clarification of some colloidal unstable organic sub stances contributing to this deterioration. Although there has been a loss of total sugars in each of the commercial citrus molasses samples during storage, the corresponding change in degree Brix is so small as to be insignificant, being but a fraction of the percent of total sugars lost. The froth fermentation or spontaneous foaming of molasses has been the subject of much inquiry, for even though it hap pens infrequently, it can be a serious economic loss. This phenomena occurs when molasses spontaneously heats to such high temperature as to "boil" and foam out of its storage tank leaving but . a charred mass. Usually the molasses foams to some multiple volume that is greater than the storage space available. All attempts to correlate this instability with some other chemical or physical analysis have been futile to date. Owen (6) corroborates this and further states regarding blackstrap "that actual de terioration involving loss of sugars is accompanied by gas evolution, but it is also true that the latter cannot be taken as an indication of the destruction of sugars." Manometric measurement of gas evolution from various citrus molasses samples was similarly found not to correlate with loss of sugars. This gas formation in citrus molasses can. also be found in concentrated orange juices and was investigated by Curl (2) who studied synthetic mixtures and found that mixtures of amino acids and sugars produced darkening and gas which was further accelerated by certain metallic ions. Rucker and Brooks (5) also demon strated that gas is produced by mixtures of nitrogen compounds and glucose, a re action which is more commonly known as the Maillard reaction. When various chemicals were added in small quantities to citrus molasses under manometric ob servation it was noticed that formalde hyde, though impractical to use, miti gated gas formation, and that pH changes on the acid side had little effect. While studying this spontaneous foam ing it was noticed that certain commer cial citrus molasses samples had shown sub-surface gas formation during the first months of storage. When these samples were disturbed they tended to foam more readily much like a carbon ated beverage. Analysis of a citrus molasses sample from a tank foaming excessively showed no significant differ ence from other samples on hand. This particular storage tank was finally con trolled by aeration which may have helped only by its agitation action on the surface foam, and it follows also that the reaction may already have spent itself. It appears significant that of twenty samples of clarified citrus molasses made in the laboratory only two have shown any sign of sub-surface gas for mation and both of these samples had an excessive precipitation of insolubles dur ing storage. None of these samples showed any sign of surface foaming and they have the further advantage of hav ing a less stable foam system. Among the conditions contributing to stable foams, are high viscosity and finely di vided solids, both of which have been re duced by clarification. Rucker and Brooks (5) have demonstrated that high viscosities tend to increase the chances of spontaneous foaming and that high storage temperatures further aggravate this condition with 40-45C. being a critical temperature range.

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HENDRICKSON A 1 D KESTERSON : CITRUS MOLASSES 157 Many explanations of froth fermenta tion have been advanced over the years, but most agreement has been found in two theories; one, the glucic acid theory which is favored by Browne ( 1 ) and re lates that the action of lime on invert sugar produces unstable organic sub stances that further reacts with invert sugar. The second i& the Maillard . -1.40 Q,) c,, 0 ... -1.20 0 (n-1.00 c,, c:: :r: Q. C -.60 0 theory whereupon it is believed that the source of gas formation is the reaction between amino acids and invert sugar. Rucker and Brooks ( 5 ) seemed to have definitely established that microorgan isms can be considered only a minor cause. Influence of pH During Storage Although the initial pH of a citrus Q) c,, C 0 -.40 .s::. 0 0 0 14 Months Storage Time 20 Months Storage Time -.20 7 6 . 5 6 5 . 5 5 Original Molasses pH Figure 1. A scatter diagram comparing the change in pH of clarified citrus molasses after 14 months storage versus the change for commercial citrus molasses after 20 months.

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158 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 press liquor is almost entirely controlled by the quantity of hydrated lime added to the chopped citrus peel, there are cer tain other factors to be considered in arriving at the final pH of a citrus molasses sample in storage. Attempt should be made to control the initial pH of citrus molasses between the limits of 6.0 to 6.5 with due thought given to the destructiveness and other inherent dis advantages of excessive alkalinity on sugars. Consideration must be given by processors to the corrosive and destruc tive influence of a too acid molasses on storage equipment. It is generally real ized that grapefruit peel demands a greater quantity of lime than orange, however, during processing and upon prolonged heating it is to be further noted that both citrus press liquor and molasses will decrease in pH. This de crease in pH averaged one unit for 14 samples that were processed to citrus molasses in the laboratory . During storage there is a further drop in pH of citrus molasses samples. The decre a se in pH appears to be dependent upon both the time of storage and the pH of the sample at the time it was put in storage. Figure 1 is a scatter diagram of 11 sam ples of clarified citrus molasses stored for 14 months and 17 samples of commer cial citrus molasses that have been stored for 20 months, wherein the change in pH during storage is plotted against its pH at the time it was put in storage. Be low a pH of 4.5 the decrease in pH with time is of smaller magnitude than would be anticipated from this figure and would appear to be approaching a point of little change. Prior to storage the quantity of total sugars found as reducing sugars in citrus molasses is definitely related to the pH of the processed molasses. As was similarly found in the analysis of Va lencia orange juice by Roy (7), the lower the pH the greater the ratio of reducing to nonreducing sugars. In storage it was noticeable that almost without ex ception the percent of total sugars as invert sugar had increased with there being a tendency for the samples having the lower pH to show the greater percent change. In studying the clarification of citrus molasses it was found that in storage clarified molasses precipitated consider able insoluble matter and that variations in pH between 4 and 8 did not, perceptibly decrease the quantity precipitating. It is also to be noted that pH could not in any way be correlated with sugar losses, or spontaneous frothing of citrus molasses. Physical Changes During Storage It has undoubtedly been previously recognized that citrus molasses upon storage tends to increase in viscosity, sometimes appearing to gel, but hitherto an explanation has been lacking . This increase is strikingly seen in Figure 2 in which is plotted the viscosities of 18 samples of commercial citrus molasses after over one year of storage against their Brix, versus 11 samples of commer cial citrus molasses that had been in storage only one month. The regression lines show a considerable increase in viscosity with time. Four other molasses samples whose Brix were between 68 and 73 had solidified and are not shown in this diagram. The wide variation of viscosities for samples of similar Brix is largely due to the quantity of sus pended insolubles present. When the viscosities of many clarified molasses samples were plotted in similar fashion against those of nonclarified citrus molasses by Hendrickson ( 4), the regres sion line for clarified molasses showed its viscosity to be seven times smaller and showed less viscosity variation between samples. The influence of temperature and Brix upon the viscosity of an excel lent sample of commercial citrus molasses prior to storage can be seen in Figure 3.

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HENDRICKSON AND KESTERSON: CITRUS MOLASSES 159 ,oo.....---.......-----------------------90 ' 80 70 60 50 40 o 30 0 .0 + 20 ti) Q) ti) 0 0. C: Q) 0 10 C 9 en Q) (,/) 8 6 0 5 4 ... : 0 3 . ) 0 >, 2 1/) 0 u Cl) > 0 0 0 0 0 0 Oo 0 0 0 0 After over I Year After approx . I Month 71 72 73 74 75 76 Degree Brix Figure 2. A scatter diagram comparing the viscosity at 30G. of citrus molasses samples stored for over one vear versus samples that had been in storage ap• proximately one month,

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160 0 aoo 600 400 200 0 100 -I' 80 t1> 60 th a . 940 (: ' Q) o 20 10 8 4 0 60 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 64 10 0 ff 20 68 72 76 80 Temperature . vs Viscosity Degrees Brix vs Viscosity At 75. 0 ., Br i x A t 3 0.0 C entigrade / / / / / / / 30 I >3 1/ I I I I I I 40 I p I I I I I I 50 I I I I I I I I 60 Temperature O c. , , ____ _ 84 70 Figure 3. Influ ence of concentration and temperature upon the viscosity of citrus molasses.

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HENDRICKSO AND KESTERSON: CITRUS MOLASSES 161 Since the insoluble matter is mostly responsible for the wide variations in viscosity, it is well to examine the source of insolubles. Prior to concentrating citrus press liquor to citrus molasses it has been noted as having anywhere from 0.2-0.5 percent by weight insoluble mat ter depending upon how it has been screened and the degree of liming. Dur ing the process of evaporation another one to three percent, on a citrus molasses basis, of calcium organic salts are esti mated to precipitate. In storage a con siderable quantity of insoluble matter has been noted to precipitate which is especially noticeable in clarified citrus molasses samples. A greater quantity of insolubles was found to precipitate from clarified grapefruit molasses than from the clarified orange samples, with one sample of grapefruit molasses pre cipitating 5.6 percent insolubles by weight, two-thirds of which was soluble in alcohol. It is not strange then for the amount of insolubles to build up to a rather high percentage. For example , one commercial molasses sample that had solidified was observed to have 9.6 per cent insolubles . Examining more closely the volumin ous quantity of insolubles precipitating from grapefruit molasses samples it was noted that the majority of insolubles were crystalline and appeared as clusters of needles growing from common cen ters. In Figure 4 is shown a photo micrograph of these crystals which were subsequently identified as naringin. The very bulkiness of these crystalline needle formations, as well as the quantity of it, and the percent of calcium organic salts precipitating in storage points to the cause of increasing viscosities in storage. By heating the citrus molasses the naringin crystals will, by virtue of their increased solubility, go back into solution and remain as a supersaturated solution for some time. Hesperidin has not been isolated from orange molasses to date. Conclusions In retrospect, citrus molasses was found to lose an average of 2-3 percent total sugars per year of storage while clarified citrus molasses showed little if any loss. There was little change in degree Brix of these samples, being but a fraction of the sugar loss. Those molasses samples having the highest total sugars appeared most susceptible to loss of sugars in storage although other unknown factors would appear to be equally important. The spontaneous foaming of citrus molasses was investi gated, but could not be correlated with any chemical or physical analyses. Clari fied citrus molasses , however, showed a perceptible improvement in stability. The pH of citrus molasses was noted to decrease with time and was greatest for those samples having the higher pH. Below a pH of 4.5 the samples appeared to approach a point of little change . The ratio of reducing to nonreducing sugars F igure 4 . A 1nicrophotogr aph of narin gin in citrus molasses. (Magni fi ed 50 X) was found dependent in part upon pH and there was a tendency for samples having the lower pH to show the greater increa se in percent inversion. During storage, there was an increase in viscosity which was felt to be caused by the quantity of insolubles precipi tating. Upon closer examination ,;ome of the insolubles were found to be

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KEW AND VELDIIUIS: INDEX OF PASTEUHIZATION 163 Lineweaver (3). With heated samples the pH changes occurred very slowly. The test developed and patented by J. W. Stevens (4) was tried with the kind permission of the California Fruit Grow ers Exchange. This test involves the ad dition of barium chloride, pectin, a pre servative and pH adjustment to 2 . 9-3.0. The samples were placed at 37C. for 72 hours and then centrifuged. A clear supernatant liquid indicates enzyme ac tivity. This test was satisfactory in many respects, but the elapsed time in volved (72 hours) was objectionable and difficulty was experienced in judging borderline samples. The next test was that described by Kertesz (5). This test had been devised for determining pectinesterase activity in tomato juice and involves the addition of methyl red indicator, and just suffi cient alkali to cause the red color of the indicator to disappear. The reappear ance of the red color was the indication of pectinesterase activity. This test worked very slowly in fresh orange juice and was not suitable as an indication of inactivation of the enzyme. The use of a colored pH indicator has some advantages in that no elaborate equipment is required, so an effort was made to modify the test. The amount of enzyme was increased by using more juice relative to the amount of pectin. Equal volumes of juice and 1 percent pectin solution were used. This improved the test but it was still too slow to be useful. MacDonnell, Jansen and Line weaver (3) reported that this enzyme was largely associated with the suspended matter in citrus juices and used a buffer containing sodium chloride or sodium acetate to bring the enzyme into solution. This provided the suggestion that sodium chloride be used to bring the enzyme into solution so that it would act more rap idly. With the addition of sodium chloride, . encouraging results were ob tained and definite changes in the color were soon noticeable after adjusting the pH. However, Lineweaver and Ballou (2) had noted that the addition of suit able amounts of divalent cations (calcium or magnesium salts) resulted in an in crease in pectinesterase activity. Mac Donnell, Jansen and Lineweaver (3) showed that "by the addition of suitable amounts of various salts, the activity of orange pectinesterase was increased five fold at pH 7.5 and more than 100-fold at pH 5." The use of calcium or magnesium chloride with the other reagents men tioned resulted in a decided stimulation in the enzyme activity. When salts were applied in amounts suggested by Mac Donnell, Jansen and Lineweaver (3) to citrus juices even with very low pecti nesterase activity, the red color returned in four hours or less. With fresh juice the change was evident within ten min utes. The effect of temperature was ob served by dividing the reaction mixtures into two portions in test tubes, placing one at 40 F and the other in crushed ice. The samples held at the higher tempera ture turned red sooner than the re frigerated samples. However, as might have been expected from the literature (2) the effect was not great and since one of the objects was to keep the test as simple as possible, it was decided that room temperature would be used and this was found to work very well. An effort was made to use a mixed indicator. It was thought a combination of methyl red and methylene blue (John son and Green (6) ) might improve the sensitivity of the test by providing a striking color change. The color change was from very light green to purple and very spectacular, but the test would not work. Apparently methylene blue in hibits the action of this enzyme. No buffers were added or needed. Citrus juices are well buffered naturally. The method we have found most satis factory permits all the reagents to be

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164 FLOlUDA STATE HOHTICULTUHAL SOCIETY , HJ50 added in two solutions. As many as po s sible of the reagents were combined into one solution. This solution contained the pectin, sodium chloride, calcium or magnesium chloride, and methyl red. Sodium benzoate added to this solution will retard microbial growth but will not prevent degradation of the indicator. The main solution is prepared as follows: Solution A To one liter of distilled water, 12 grams of 150 grade pectin are added and thoroughly mixed in a Waring blendor. A little of the pectin sticks to the jar so the resulting solution is about 1 % pectin. Then 17.54 grams of sodium chloride are added (0.3 M) and 14.7 grams of CaCb.2H,O (0.1 M). To this 3 ml. of a freshly prepared 1 % alcoholic solution of methyl red indicator are added. The solution is kept in the re frigerator. Solution B The other reagent is approximately 1.0 normal sodium hydroxide solution (40 g.jliter). In performing the test an equal quan tity (20 ml.) of canned citrus juice and the reagent are mixed. The 1.0 normal sodium hydroxide solution is added with a medicine dropper with adequate mixing until the red color just disappears. By using approximately 1 N NaOH less dilu tion is obtained than with .1 or .01 N alkali. Citrus juice is naturally buffered so that no difficulty is experienced in ob taining suitable pH adjustment with the stronger reagent. The sample is then observed for the return of the red color. If pectinesterase is active, methyl ester groups are hydrolysed in the pectin, acid groups exposed, and the solution turns more acid, changing the indicator back to red. In fresh juices the color change is sufficient to be noticed in about fifteen minutes. With heated juices up to four hours have been observed to elapse before the color develops. When the enzyme has been inactivated there is no .:olor change. As a confirming test for the presence of the pectinesterase enzyme, the sam ples can be stoppered and placed in the refrigerator overnight. If there is much enzyme activity, a solid gel will form. In borderline cases lumps will form which can be observed by slowly inverting the flask. This confirmatory test is at least as sensitive as the color change, the only objection being that several hours are required for the setting of the gel or forming the lumps. If a pH meter is available, changes in pH can, of course, be detected more satis factorily with it than with the color indi cator, but such an instrument is not essential. The test has been applied to several hundred samples. Comparisons have been made with the Stevens (4) test. In the experimental work mentioned at the start of this paper, time and temperature of pasteurization tests were made. The temperature intervals, were 5 F. Both the new test and the Stevens test were applied to these series and temperature of enzyme inactivation was determined. In one series, enzyme inactivation at 5 higher temperature was indicated by the new test. In fifteen series the results were identical. In twenty-seven series of samples the new test indicated inactiva tion temperatures 5 lower than the Ste vens test. In one series the new test in dicated a 10 lower inactivation tempera ture. In sixteen series the new test indi cated the temperature of inactivation and the Stevens test gave borderline or in decisive results. The new test indicates temperatures of enzyme inactivation averaging less than 3 lower than the Stevens test. A complete listing of the inactivation temperatures along with a discussion of the factors affecting this temperature is to be presented in another paper.

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}.100RE, IIUGGAHT AND HILL: CONCENTHATED CITHUS 165 Since the temperature needed for enzyme inactivation is above that used to pasteurize citrus juices, it is sug gested that this rapid test for pectines terase inactivation be used as an indica tion that adequate pasteurization tem peratures have been used. Summary The new procedure has been devised and described for testing the effective ness of the pasteurization of citrus Jmces. Evidence of the presence of pectinesterase is used as the index. The test is rapid in that it can be completed in four hours. A color indicator is used to detect changes in acidity in the pre pared sample. The test is simple, re quiring only two solutions, and can be easily performed in the control labora tory. A confirmation of the test can be obtained by setting the prepared sample in the refrigerator overnight. The test agrees well with the results of other tests. REFERENCES I. JAN SEN, E. P. Private communication, Septem ber 14, 1949. 2. LrnwEAVEn, H., and BALLOU, G. A. "The Effect of Cations on the Activity of Alfalfa Pectinc sterase (Pcctase)." Arch. Biochem, 6. 373-387. 1945. 3. MACDONNELL, L. R., JANSEN, E. F., and LINE WEAVER, H. "The Properties of Orange Pec tinesterasc." Arch . Biochem. 6: 389-401. 1945 . 4. STEVENS, JESSE W. "Method of Testing Fruit Juices." U. S. Patent No. 2,267,050, December 23, 1941. 5. KERTESZ, Z. I. "Pectic Enzymes III. Heat In activation of Tomato Pectin-!-fethoxylose ( Pee . tose)." Food Research 4: 113-116. 1939. 6. JOHNSON, ARNOLD H., and GnEEN, JESSI R. "Modified ~!ethyl Red and Sodium Alizarin Sulfonate Indicators." Analytical Edition of In dustrial and Engineering Chemistry, January, 1930, p. 2-4, Vol. 2, No. 1. STORAGE CHANGES IN FROZEN CONCENTRATED CITRUS JUICES-PRELIMINARY REPORT 1 2 EDWIN L. MOORE3, RICHARD L. HUGGART3, AND ELMER C. HILL 3 Citrus Experiment Station Lake Alfred The purpose of this investigation, started in the 1949-50 season and now in progress, is to determine what effect temperature of storage will have on the quality of frozen concentrated citrus Jmces. In order that high quality may be retained, frozen citrus concentrates should be stored at temperatures suffici1 Cooperative research by the Florida Citrus Com mission and the Florida Citrus Experiment Station. > Paper presented by Richard L. Huggart at the 63rd Annual Meeting of the Florida State Horticultural Society, Winter Haven, Florida, November 1, 1950. Research Fellow, Florida Citrus Commission; also cooperating were C. D. Atkins, Florida Citrus Com mission, and Robert W. Olsen, L. W. Faville, F. W. 'Nenzel, and Dorothy Asbell, Citrus Exp e riment Station. ently low so that any chemical, micro biological, or enzymatic changes that may cause deterioration will be prevented or kept at a minimum. Curl (3) studied the effects of degree of concentration and of temperature of storage on various characteristics of orange juices, that had been pasteurized prior to concentration and subsequently benzoated and stored at temperatures of 40 F. and above. Cotton and associates (2) made studies on frozen orange and tangerine concentrates stored at various temperatures. They reported excellent retention of aroma, taste, ascorbic acid and "cloud during storage at _ 0 F., but storage at 40 F. resulted in clarification, separation and flavor degradation. Rouse (4) presented data on gel formation in frozen citrus concentrates that had been thawed and stored at 40 F. His data indicated that the presence of low

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166 FLORIDA STATE HOHTICULTUHAL SOCIETY, 1950 methoxyl pectin, which resulted from the activity of the pectic enzyme, pectase, is the cause of gelation in frozen citrus concentrates during storage at 40 F. At the beginning of the 1949-50 season it was evident that there was a need for more data, than were then available, in order to advise processors, transportation companies, wholesalers, retailers, and consumers concerning the changes that will take place if frozen citrus concen trates are mishandled by storage at elevated temperatures during any part of the period from the time the products are processed until they are used by the consumer. At the time this investiga tion was begun, it was generally believed that a temperature of 0 F. was suffici ently low to prevent deterioration, and that this low temperature should be maintained at all times during storage, transportation, and distribution of these products. Experimental Procedure The six packs of frozen concentrated citrus juices used in this investigation were processed in the pilot plant at the Citrus Experiment Station using an evaporator described by Atkins and as sociates (1), and included the following citrus varieties: Hamlin, Pineapple, and Valencia oranges, Dancy tangerines, and Duncan and Marsh grapefruit. The pro cessing procedure used may be outlined briefly as follows: (a) fruit washed and graded, (b) juice extracted by rotary press, (c) juice for concentration passed through 0.030 inch finisher screen, (d) cut-back pulpy juice secured by passing pulp and seeds from (c) mixed with some juice through 0.125 inch finisher screen, (e) sugar added to tangerine and grape fruit juices, (f) juice concentrated to approximately 55 Brix, (g) 55 Brix concentrate cut back to approximately 42 Brix with fresh pulpy juice from (d), (h) slush frozen in Votator, (i) machine filled and vacuum closed in 6-oz. plain tin cans, and (j) frozen by storage at -8 F. This processing procedure simulated commercial methods during the 1949-50 season with the probable ex ception in these pilot-plant packs of lower juice yield and possible slower rate of final freezing. After the packs had been in storage at -8 F. for one day, samples for this investigation were stored at -8, 10, 20, 32, and 40 F. It was not possible to include 0 F. stor age as facilities for this temperature were not available. Periodic chemical and microbiological examinations of these packs are planned for at least a period of one year. Fre quency of examination depends upon the storage temperature and other factors. Examinations include (a) Brix, (b) total acid, (c) peel oil, (d) ascorbic acid, (e) pH, (f) color, (g) pulp, (h) headspace, (i) vacuum, (j) clarification, (k) pectase activity, (I) gelation, (m) viscosity, (n) microbiological counts, and (o) flavor. Only the data summarizing the more important changes, especially gelation and clarification, that have occurred in the concentrates during storage for six months will be presented in this pre liminary report. Experimental Results and Discussion Some of the initial analyses of the six concentrated citrus juices together with the dates at which the fruit was pro cessed are presented in Table 1. It will be noted from this table that the tan gerine concentrate had a low pectase ac tivity as compared to the other five con centrates. All varieties of fruit were held at room temperature from the time of picking until processing. Gelation of the Concentrates: The data for gelation of Hamlin, Pine apple, and Valencia orange concentrates and Dancy tangerine concentrate are presented in Table 2. In this table and also in Table 3, the degree of gelation is

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MOOHE, HUGGART AND HILL: CONCENTRATED CITHUS 167 indicated by the numerals 0, 1, 2, 3, and 4, these referring respectively to a de gree of gelation of none, very slight, slight, semi-gel, and solid-gel. The oc currence of a semi-gel or a solid-gel in a frozen citrus concentrate would cause consumer complaints. Rouse (4) shows a picture of a semi-gel and a solid-gel in frozen concentrated citrus juices. It will be noted from Table 2 that after storage of these four concentrates at -8 F. for six months, only the Pine apple orange concentrate showed any in dication of gelation and that was very slight. Very slight gelation occurred in all three orange concentrates after three months storage at 10F., and in the tan gerine concentrate after six months TABLE 1. INITIAL ANALYSES OF THE CONCENTRATED CITRUS JUICES. Hamlin Pineapple Valencia Dancy Duncan Marsh Orange Orange Orange Tangerine Grapefruit Grapefruit Date fruit processed 1-26-50 2-15-50 4-20-50 1-25-50 2-21-50 2-28-50 Brix, 28 C., corrected for acid 42.3 42.1 42.2 42.1 42.1 41.9 Total acid, % as anhydrous citric 2.78 2.98 3.25 2.93 4.64 4.03 Maturity ratio: Brix/ acid 15.2 14.1 13.0 14.4 9.1 10.4 pH 3.6 3.7 3.6 3.6 3.1 3.3 Ascorbic acid, Mg./100 gm. 205.8 211.5 158.5 73.9 136.2 129.4 Pectase activity 1 5.65 6.42 6.35 1.85 6.34 6.81 Microbiological count on D.A. 2 16,500 57,200 76,200 33,300 3,700 13,200 Microbiological count on P.D.A 3 4,480 19,100 28,300 4,200 2,020 3,860 ' Expressed as mg. methoxyl released per hour per gm. of soluble solids. 'D. A. is Dextrose Agar, pH 7.0. 1 P. D. A. is Potato Dextrose Agar, pH 3.5. storage at this temperature. Pineapple orange concentrate showed a semi-gel after two months storage at 20F., and after two weeks storage at 40F. Even after six months storage at 40F., the other two orange concentrates showed only a slight gel, and the tangerine con centrate showed only a very slight gel. The data for gelation of Duncan and Marsh grapefruit concentrates are pre sented in Table 3. Duncan grapefruit concentrate showed the fastest rate of gelation of any of the six concentrates. Very slight gelation occurred in this concentrate after three months storage at -8F., and after two months storage at 10F. Semi-gels occurred in the Dun can grapefruit concentrate after one months storage at 20F., and after two weeks storage at 32 or 40F. Marsh grapefruit concentrate showed no gelation after six months storage at -8F., but did show very slight gelation after four months storage at 10F., and after two weeks storage at 20, 32, or 40F. Even after six months storage at 40F., the Marsh grapefruit concentrate showed only a slight gel. On the basis of the results presented for gelation in these six concentrate packs, it is indicated that a degree of gelation which would be definitely objec tionable from the consumer standpoint occurred only in the Pineapple orange concentrate and Duncan grapefruit con centrate that were stored for sufficient periods of time at temperatures of 20, 32, or 40F. This might be an indica tion that gelation occurs to a greater extent in concentrated juice from seedy

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16 8 FLOlUDA STATE IIOHTICUL TUHAL SOCIETY , H.)50 TABLE 2. DEGREE OF GELATION OF CONCENTRATED ORANGE AND TANGERINE JUICES•. Time and T em p era tu r e of Storage Variety Period -8F. lO'F . 20 ' F. 32'F. 40'F. Initial 0 0 0 0 0 1 week 0 0 0 0 0 2 weeks 0 0 0 0 0 1 month 0 0 0 0 0 Hamlin Orange 2 months 0 0 1 2 2 3 months 0 1 2 2 2 4 months 0 1 2 2 2 6 months 0 1 2 2 2 Initial 0 0 0 0 0 1 week 0 0 0 0 0 2 weeks 0 0 0 2 3 1 month 0 0 1 3 3 Pineapple Orange 2 months 0 0 3 3 3 3 months 0 1 3 4 4 4 months 0 1 3 4 4 6 months 1 1 3 4 4 Initial 0 0 0 0 0 1 week 0 0 0 0 1 2 weeks 0 0 1 1 1 1 month 0 0 1 1 1 Valencia Orange 2 months 0 0 1 2 2 3 months 0 1 2 2 2 4 months 0 1 2 2 2 6 months 0 1 2 2 2 Initial 0 0 0 0 0 1 week 0 0 0 0 0 2 weeks 0 0 0 0 0 1 month 0 0 0 0 0 Dancy Tangerine 2 months 0 0 1 1 1 3 months 0 0 1 1 2 4 months 0 0 1 1 2 6 months 0 1 2 1 1 eg ree of gelation: 0=Non e; l=V e ry slight; 2=Slight; 3=Semi-g e l; 4=Solid gel.

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MOORE , HUGGAHT AND HILL: CONCENTHATED CITHUS 169 TABLE 3. DEGREE OF GELATION OF CONCENTRATED GRAPEFRUIT JUICES 0 Time and Temperatur e of Storag e. Variet y P eriod -8F . l0 F . 20 F. 3 2F. 4 0F Initial 0 0 0 0 0 1 week 0 0 0 0 0 2 week s 0 0 1 3 3 Dunc a n 1 month 0 0 3 3 4 Grapefruit 2 months 0 1 3 3 4 3 months 1 1 3 3 4 4 month,; 1 2 3 4 4 6 month:; 1 2 4 4 4 Initial 0 0 0 0 0 1 week 0 0 0 0 0 2 weeks 0 0 1 1 1 Marsh 1 month 0 0 1 1 1 Grapefruit 2 months 0 0 1 1 1 3 months 0 0 2 2 2 4 months 0 1 2 2 2 6 months 0 1 2 2 2 0 Degr ec o f ge l ation: 0 = N o n e ; 1 = Very Sli g ht; 2 = Slight; 3 = Semi-g e l; 4 = Solid gel. varieties of citrus fruit, such as Pine apple orange and Duncan grapefruit, than in the concentrated juice of varieties containing fewer seeds such as Hamlin and Valencia orange and Marsh grape fruit. Clarification of the Concentrates A citrus concentrate might not be acceptable to a consumer because of clarification or loss of "cloud." Loss of "cloud" is a further clarification than the usual settling of the chromatophores or color bodies of the juice. The pectic enzymes act on the pectin responsible for the "cloud," resulting in precipitation of colloidal particles, and finally leaving a clear supernatant liquid. The turbidity or "cloud" in all concen trates was determined by centrifuging a sample of the reconstituted juice (25 gm./100 ml.) for 15 minutes at 1700 r.p.m. in an International Centrifuge, Size 1 , T y pe SB, and reading the light transmission of the centrifugate in a Lumetron Colorimeter, Model No. 402-E, using a rectangular absorption cell (juice thickness, 10 mm. ) and a filter No. 730, that was calibrated to read 100 with distilled water. With this filter a com pletely clarified juice will read 98 to 100 percent transmission despite its color, and the presence of turbidity or "cloud" in the centrifuged juice reduces the light transmission by dispersion and ab s orp tion. The data for clarification of reconsti tuted juices of Hamlin, Pineapple, and Valencia orange concentrates and Dancy tangerine concentrate are presented in Table 4. In this table the degree of clarification is indicated by the perc e nt age light transmission of the centrifuged Juices, as follows: 50-60 % = none; 60-70 % = slight ; 70-85 % = definite; 85-100 % = extreme. The data in Table 4 indicate that a temperature of 20F. was too high for the proper storage of the orange and tan gerine concentrates on the basis that definite c larificati on in these concen trates, which might b e noticeable to the

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170 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 TABLE 4. CLARIFICATION OF RECONSTITUTED ORANGE AND TANGERINE JUICES. 0 Variety Time and Temperature of Storage. Hamlin Orange Pineapple Orange Valencia Orange Dancy Tangerine Period Initial 1 week 2 weeks 1 month 2 months 3 months 4 months 6 months Initial 1 week 2 weeks 1 month 2 months 3 months 4 months 6 months Initial 1 week 2 weeks 1 month 2 months 3 months 4 months 6 months Initial 1 week 2 weeks 1 month 2 months 3 months 4 months 6 months -8'F. 62 64 63 65 64 67 67 63 58 60 62 62 60 59 61 59 54 57 58 55 57 54 55 56 55 56 57 55 56 58 57 54 lO'F. 62 66 66 74 73 78 81 75 58 61 64 66 64 60 61 59 54 60 64 60 59 56 60 59 55 57 55 58 59 60 58 57 20'F. 62 76 85 97 97 99 98 98 58 63 72 85 97 84 97 98 54 61 64 65 87 75 91 91 55 60 58 74 77 84 84 94 :32'F. 62 97 98 99 98 99 97 98 58 74 96 98 99 99 98 98 54 66 89 94 93 89 95 94 55 71 85 99 99 100 99 99 40'F 62 98 99 100 98 99 97 97 58 91 98 99 98 99 98 98 54 81 96 95 92 88 93 91 55 81 98 100 99 100 99 98 0 Reconstituted 25 gm./100 ml. Clarification measured by light transmission of centrifuged juices. Degree of clarification: 50-60% = None; 60-70% = Slight; 70-85% = Definite; 85-100% = Extreme. consumer, is indicated by a light trans mission of 70 percent or higher. Definite clarification occurred after one month in the Hamlin. orange concentrate stored at 10F. At -8F. there was no evidence of clarification in the orange concentrates or tangerine concentrate after six months storage. The data for clarification of reconsti tuted juices of Duncan and Marsh grape fruit concentrates are presented in Table 5. In this table the degree of clari

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MOORE, HUGGART AND HILL: CONCENTRATED CITRUS 171 TABLE 5 . CLARIFICATION OF RECONSTITUTED GRAPEFRUIT JUICES. 0 Variety Time and Temperature of Storage. Period -8F. 10F. 20'F. 32'F. 40F Initial 69 69 69 69 69 1 week 71 68 74 95 96 2 weeks 86 89 95 96 96 Duncan 1 month 88 94 95 97 97 Grapefruit 2 months 83 98 95 96 97 3 months 90 94 96 99 99 4 months 77 93 95 96 96 6 months 92 95 96 96 96 Initial 62 62 62 62 62 1 week 70 68 75 92 94 2 weeks 75 78 92 95 96 Marsh 1 month 87 89 95 97 97 Grapefruit 2 months 70 80 92 98 98 3 months 72 85 94 97 97 4 months 72 79 95 97 97 6 months 75 88 96 96 94 0 Reconstituted 25 gm./100 ml. Clarification measured by light transmission of centrifuged juices. Degree of clarification : 60-70% = None; 70-80% = Slight; 80-90% = Definite; 90-100% = Extreme. fication is indicated by the percentage light transmission of the centrifuged Jmces, as follows: 60-70% = none; 70-80% = slight; 80-90% = definite; 90-100% = extreme. The data in Table 5 indicate that a temperature of 10F. was too high for the proper storage of the two grapefruit concentrates on the basis that definite clarification in these concentrates, which might be noticeable to the consumer, is indicated by a light transmission of 80 percent or higher. Even at -8F., defi nite clarification occurred in the Duncan grapefruit concentrate and slight clarifi cation occurred in the Marsh grapefruit concentrate. The Marsh grapefruit con centrate did not show such an objection able degree of gelation as the Duncan grapefruit concentrate; however, it showed clarification at practically the same rate as Duncan grapefruit concen trate at storage temperatures of 20 , 32, and 40F. The results on gelation and clarification indicate that the temperature of storage is an important factor and that as the temperature is increased, the rate of clarification and gelation become greater. Although both are the result of enzymatic changes, clarification took place in these citrus concentrates at a faster rate than did gelation. Slight flavor changes were noted to follow the trend of gelation and clarification. Retention of Ascorbic Acid in the Concentrates The average retention of ascorbic acid in all six concentrates stored at -8F. for six months was slightly over 98 percent, decreasing gradually with an increase in storage temperature to slightly over 96 percent average reten tion for six months storage. at 40F. So although the concentrates in some in stances may have gelled, clarified, and developed slight flavor changes, there was no appreciable decrease in the ascorbic acid content.

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172 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 Microbiological Plate Counts on the Concentrates Microbiological plate counts were made initially on the six different packs of frozen concentrate after storage at -8 F. for one day (See Table 1). The packs were examined at intervals of one month for a period of six months after 35.0r----------------------, 0 31.5 10 20 30 .., 0 ~21.0 z 40 0 I(/) 0 ::E => 17.5 0 50 w z a:
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MOORE, HUGGART AND HILL: CONCENTRATED CITRUS 173 being placed at storage temperatures of -8, 10, 20, 32, and 40F. A total count was obtained by plating with Dextrose Agar, pH 7.0, incubated for 48 hours at 30C. (86F.). A yeast and mold count was determined by plating on Potato Dextrose Agar, pH 3.5, incu bated at room temperature for five days. The concentrate stored at 40F. showed an immediate sharp reduction in total count leveling off at about two months. The reduction in total count of the concentrate at -8F. storage was much slower with a gradual decrease over the entire six months. After six months, the average reduction in total count of all packs stored at -8F. was 80 percent while 40F. storage packs had an average reduction in total count of 96 percent. The packs stored at 32F. closely paralleled the 40F. storage packs in reduction of organisms. Packs stored at 20F., although showing a smaller reduction in the first month, closely ap proached in the third month those packs stored at the two higher temperatures. Reduction of microorganism count in packs stored at 10F. was less rapid than in packs stored at 20F . Average values of the total counts for all six packs stored at each temperature were calculated for each examination period in order to determine the trend in the reduction of total count for a period of six months. These trends are shown in Figure 1. The yeast and mold count presented a somewhat different picture in that the reduction was more gradual. Initial yeast and mold counts are presented in Table 1. After the second month the yeast and mold count was very close to that of the total count in the 20, 32, and 40F. packs, indicating that the total count at these later examinations was made up primarily of yeast and that few of the surviving organisms in these packs were bacteria. Summary Six packs consisting of Hamlin, Pine apple, and Valencia orange, Dancy tan gerine, and Duncan and Marsh grape fruit concentrates were prepared dur ing the 1949-50 season. Samples of the freshly . frozen concentrates were stored at -8, 10. 20, 32, and 40F., tem peratures that approximate those to which concentrates may be subjected by processors, wholesalers, retailers, and consumers. Pe 0 riodic examinations of these samples are being made over a period of one year. Results obtained after six months in dicated no appreciable decrease in ascorbic acid content in any of the sam ples. Gelation and clarification were more pronounced in the concentrates prepared from seedy varieties of fruit. Clarification and varying degrees of gelation occurred in all samples stored at 20, 32, and 40F., and the rate of clarification was greater than that of gelation. Varying degrees of gelation and clarification occurred in some of the samples stored at 10F. and in the Duncan grapefruit concentrate stored at -8F. Slight flavor changes were noted to follow the trend of gelation and clarification. The concentrate stored at 40F. showed immediate sharp reduction in total microbiological count leveling off at about two months. The reduction in total count of the concentrate at -8F. storage was much slower with a gradual decrease over the entire six months. After six months, the average reduction in total count of all packs stored at -8 F. was 80 percent while 40F. stor age packs had an average reduction in total count of 96 percent. LITERATURE CITED 1. ATKINS, C. D . , WENZEL , F. W., and MOORE, E. L. Report N e w Te chn ic a l Strid es in D es ign of FCC Evaporator. Food Industries 22: 1353, 1466, 1467. 1950. 2, COTTON, R. H ., ROY; W. R,, BROKAW, C, H,,

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174 FLOHIDA STATE HORTICULTUHAL SOCIETY, 1950 McDuFF, 0. R., and SCHROED E R , A. L. Storage Studi e s on Frozen Citrus C o n ce ntrat es . Pro ce e dings of the Florida State Horticultural Society 60: 39-50 . 1947. 3. CuRL , A. L. Concentrat e d Ornng e Juice Stor ag e Studies. The Effects of D e gr ee of Concen tration and of Temperature of Storag e . The Cann e r 10 5 : (1 3 ) , 14-16, 38 , 40, 42. S e pt e ber 20 , 1947. 4. Rou s E , A. H. Gel Formation in Frozen Ci!Tu s Conc e ntrat e s Th a w e d and Stored at 40 F. Proceedings of th e Florida State II orticultural Society 62 : 170-173. 1949. A METHOD FOR ESTIMATING SOLUBLE SOLIDS IN . DRIED CITRUS PULP OWEN W,. BISSETT U. S. Citrus Products Station 1 Winter Haven Introduction Inquiries and requests on the part of processors of dried citrus pulps and citrus molasses indicate a need for a method whereby the soluble solids present in commercial, dried citrus pulps might be estimated. Processors are adding molasses at varying rates to pressed pulps prior to drying. Few, if any, operators use proportioning equipment to control the process and very little is known concern ing the storage life or keeping qualities of the products as related to the molasses content. The problem facing the indus try is therefore twofold : ( 1) Develop ment of a method for evaluating the molasses, or soluble solids, content of the finished products; and (2) studying the hygroscopic characteristics as related to storage life of dried citrus pulps contain ing varying amounts of citrus molasses. This latter problem will be the subject of a later report. The method for estimating the soluble solids content of dried citrus pulps should be simple and reasonably accurate, such that it would have practical application in the processing plants, for the purpose of differentiating sweetened and unsweet ened feeds as well as establishing the 1 On e of the laboratories of th e Bur e au of Agricul tural and Industrial Chemistry, Agricultural Re s earch Administration, U, S. Department of Agriculture. relative mola s ses content in terms of soluble solids. Official methods of analysis (2) are tedious and time-consuming, and require use of equipment not generally available in citrus pulp plants. Proces sors feel that such methods attain a de gree of accuracy not warranted and are so expensive and time-consuming as to be economically impracticable. A simple and rapid method has been developed which is satisfactory for esti mating the soluble solids. It consists primarily of dissolving the soluble solids in dried pulp samples by suspension in water, the liquid phase being removed by filtration and the Brix value of the solu:.. tion determined. Experimental results presented in this paper indicate that this method should prove valuable to the in dustry in evaluating the soluble solids content of dried citrus pulps. Preparation of Authentic Samples Two series of samples ("A" and "B") were prepared to contain pulp and mo lasses solids as follows: (1) All pulp solids (no molasses added}, (2) 90 % pulp solids and 10 % molasses solids, (3) 80% pulp solids and 20% molasses solids, ( 4) 70 % pulp solids and 30% molasses solids, (5) 60 % pulp solids and 40 % mo lasses solids, and (6) 50 % pulp solids and 50 % molasses solids. The "A" series was prepared from grapefruit pulps at 28.45 % solids and molasses at 73.7 % solids; while the "B" series represents mixed grapefruit and orange pulps of 25.9% solids and molasses at 72.0 % solids.

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BISSETT: DRIED CITRUS PULP SOLIDS 175 The materials used in preparing the above two sets of samples were obtained from commercial plants; the pulps being taken immediately following the presses. The pressed pulps were held in frozen storage and the molasses under refrig eration while being used as source materials in preparing the experimental samples. The pulp and molasses required for a given sample were weighed together in the bowl of a dough-type mixer 1 and mixed for a minimum of 15 minutes. The materials were allowed a contact period of one hour before being placed in a circulating air oven adjusted to 80 C. Samples were removed when judged to contain not over 8% moisture. Dried citrus pulps are composed of both large and small particles of the various components. In order to mini mize errors due to sampling, 400-gram samples were ground in a hammer mill 1 to pass a 1/16-inch mesh screen. After thorough mixing, small subsamples of such preparations yield reproducible analytical values. Consequently, both the laboratory preparations of pulp and the commercial pulps used in this study were prepared for analysis in this manner. Method of Analysis The soluble solids in a sample of cit rus pulp were dissolved in water and the Brix value of the liquid determined. By simple calculation the soluble solids con tent of the sample was established. To a 25-gram portion of the prepared sample 200 grams of hot water (about 70 C.) were added followed by continual moderate stirring on a hot plate, adjusted to maintain 70 to 80 C. for 20 minutes. The sample was then cooled in a water 1 Any other ty1>c of equipment having the same capabilities would serve the purpose. 2 The inention of certain trade products does not imply that they are endorsed by the Department of Agriculture over similar products not mentioned. bath to room temperature and water added based on the tare weight as re quired to replace that lost through evaporation during the heating period. The sample was again stirred for 2 min utes before filtering through a dry "filter aid" pad in a Buchner funnel using vacuum. Total soluble solids of the filtrate were determined by both refractometer and hydrometer. Iranzo and Veldhuis (1) have reported close agreement of both refractometer and hydrometer Brix val ues with that of total solids in citrus molasses. Therefore, the Brix values of the filtrates obtained in this study repre sent a soluble solids concentration of one ninth that of the original sample. The percent soluble solids was then obtained by multiplying Brix values by the factor of 9. Vacuum oven moisture values were determined on all samples and all analyses were based on a calculated moisture-free basis. Vacuum oven equipment is not generally available in commercial citrus pulp plants but practically all of them use the Dietert Moisture Teller. 2 It was felt that conditions for operation of the Dietert which would give results in rea sonable agreement with values obtained by the vacuum oven method would be of some value. It was found that 15 min utes' treatment at 230 F. of a 25-gram sample of ground pulp prepared as previ ously outlined would give satisfactory values. It should be noted that variation in particle size of sample materials would induce variable results with the "Dietert" unit and therefore the conditions here recommended should be closely followed. Discussion In establishing the sample size and ratio of sample to water, it was found that the pulp would absorb 4 to 5 times its weight of water, thus making it necessary to use a ratio greater than

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176 FLOHIDA STATE HORTICULTURAL SOCIETY, 1950 5 to 1. The use of a 25-gram sample and an 8 to 1 ratio of water to sample yields 70 ml. or more of filtrate, depending on the ratio of soluble and insoluble solids present. At least 70 ml. of solution is necessary to float a standard Brix hy drometer (graduated 0 to 10 in 0.1 units) when used with a 100-ml. gradu ate which has been found suitable. The use of a ratio greater than 8 to 1 would have no advantage but would only fur ther decrease an already low concentra tion of soluble solids in the solution. The averaged total soluble solids by both hydrometer and refractometer for all samples used in this study are given in Table I. The average deviation be tween duplicates of hydrometer values in the "A" and "B" series samples was 0.062 Brix or about 1 percent, while that of the refractometer values was 0.17 Brix or about 3 percent. Total soluble solids obtained by the refracto meter were usually higher than those of the hydrometer, the average difference being about 0.1 Brix. In this table the percent molasses added values were com puted in the .terms used by the industry, i.e., pounds of molasses added per hun dred pounds of product obtained. Com putations here are based on 72 Brix molasses and a dried product at 8% moisture. Total sugars, also given in Table I, were determined on all samples used in this study by the official Munson Walker gravimetric method (2). A correlation can be established between Brix values and total sugar values, but it TABLE 1 AVERAGE TOTAL SOLUBLE SOLIDS AND TOTAL SUGAR VALUES OF FILTRATES Mola sses Added Total Soluble Solids Total Sugars Sample % Hydrometer Refractometer % 0 Brix 0 Brix A-31 0 4.63 4.70 3.29 A-32 12.9 5.27 5.30 3.68 A-33 25.8 5.97 6.09 4.28 A-34 39.4 6.72 7.06 4.41 A-35 51.5 7.25 7.39 4.60 A-36 64.2 7.87 8.09 4.89 B-37 0 3.90 3.77 1.73 B-38 13.0 4.77 4.80 2.56 B-39 25.7 5.49 5.68 3.47 B-40 38.7 6.40 6.38 4.24 B-41 51.3 7.00 7.07 4.45 B-42 64.4 8.10 8.14 5.39 C-1 35.8 6.16 6.34 3.84 C-2 5.0 4.42 4.45 2.19 C-3 20-25 4.82 4 . 96 2.58 D-1 0 4.68 4.86 2.35 D-2 8.0 4.72 4.79 2.69 E-1 35.8 6.22 6.48 3.87 F-1 15.0 5.47 5.65 3.41 G-1 16.0 5.05 5.22 3.47 G-2 20.0 4.90 5.00 3.52 H-1 3.0 4.92 5.00 3.19 H-2 10.0 5.30 5.36 3.68

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BISSETT: DRIED CITRUS PULP SOLIDS 177 is not sufficiently clear cut to merit fur ther elaboration here. In Table II the calculated total soluble solids (that present in the pressed pulp plus that added in molasses form) may be compared with values obtained by the method ( 0 Brix x 9), as found in the "A" and "B" experimental samples. The soluble solids found in the respective nonmolasses added samples formed the TABLE 2 COMPARISON OF THE CALCULATED PERCENT SOLUBLE SOLIDS PRESENT WITH VALUES INDICATED BY THE METHOD FOR SERIES "A" AND "B" SAMPLES Soluble Solids, Soluble Solids, Sample Calculated Found % % A-31 41.7 A-32 47.5 47.4 A-33 53.3 53.7 A-34 59.1 60.4 A-35 64.9 65.2 A-36 70.8 70.7 B-37 35.1 B-38 41.6 42.8 B-39 48.1 49.4 B-40 54.6 57.6 B-41 61.1 63.0 B-42 67.5 72 . 8 basis for computing the total soluble solids values. Agreement in the "A" series is considered good while the cause of the variance observed in the "B" series is not immediately apparent. The data indicate that, when applied to prop erly prepared dried citrus pulp samples, the method will give representative soluble solids values. The relationship of percent soluble solids to percent molasses added for the "A" and "B" series samples is repre sented graphically in Figure 1. Here again the term "percent molasses added" is used to indicate the pounds of molasses used per hundred pounds of dried feed produced. The data for the samples were calculated to 8 percent moisture basis before plotting in Figure 1. The 8 per cent moisture level was chosen because that is the value which has been given by the feed producers as optimum . The two curves are quite similar and indicate a regular, progressive increase in soluble solids content with increasing molasses. However, it should be remem bered that the "A" samples represent a grapefruit pulp and the "B" samples rep resent mixed orange and grapefruit pulps. The soluble solids values of the two unsweetened experimental samples are quite different and this difference is reflected throughout the two graphs. Other samples might show even wider deviations. It is suggested, therefore, that each processor prepare his own set of reference curves rather than use those presented in this paper. Thus, by know ing the nature of the pulp being processed the operator might judge how much molasses to add in order to produce a dried product of the desired soluble solids content or vice versa. The commercial samples have also been plotted on Figure 1 and it will be noted that the values do not fall in a narrow band; however, the general trend follows that of the experimental samples. Inas much as the varieties of pulps, their moisture, and the exact amount of molasses added is not known for these samples, further observations are not warranted. The samples represent different types of dryer operation. Samples C, D, E, and H were produced in fire dryers; F in a steam tube dryer and G in a 2-stage fire and steam-tube dryer, thus repre senting a cross section of commercial operation. It is quite possible that the method of drying, as well as the inherent differences in the raw product, might in fluence the soluble solids characteristics of the product-another reason why each processor might wish to prepare his own set of reference curves.

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178 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 7 5 ----,------,,-------,-----,----.-----r----, U> C :::i 0 65 U> LLJ ..J m ::) ..J 0 55 (/J ... z D -:A: SERIES LLJ 06 // (.) 45 LETTERS C-H INCLUSIVE a:: REPRESENT COMMERCIAL LLJ SAMPLES a.. 35u________ ..__ __ _._ ___ ._ __ _._ __ __."-~ 0 20 40 60 PER CENT MOLASSES ADDED FIGURE ! SOWBLE SOUDS FOUHJ IN ~!ES ARE PLOTTED A<:AJ!il'T THE "MOUSSES ADDED" AS DEFIIIIID IN THE REPORT "A" Serie• (Grapefruit Pulp)J-"B" seriea (Mixed Ore.n~e and Grapefruit Pulpe) In most plants the molasses is added with manual control and is not strictly proportioned. The molasses content is really indicated by the amount of molasses used and the quantity of feed produced during a shift or similar period. This may account for some of the varia tion in the commercial samples. Strict proportioning should result in greater uniformity of the product. If all the molasses produced in a plant handling citrus pulp were added back, it is estimated that the dried product would contain about 36 % molasses. Thus, the data presented cover the ranges that would be expected in normal factory operation. It is felt that the simple method described here will prove of practical value to processors of dried citrus pulps con taining added molasses. The method may be used in control of plant operations to establish the approximate molasses content. Summary A simple and rapid method has been developed for the estimation of the solu ble solids content of dried citrus pulps. It is based on the use of a small portion of a large sample which is finely ground and thoroughly mixed. It is suitable for routine operation in establishing the range of molasses content of citrus pulps. In experimental samples, increasing addi tions of molasses re s ulted in the regular

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HEASONEH: GENUS ALLAMANDA 17U increase in the soluble solids values. The conditions for operation of the "Dietert Moisture Teller" which will approximate moisture values obtained by the vacuum oven method are also given. LITERATURE CITED REFERENCES 1. lRANZO, J. R. and VELDHurs, M. K. Proceedings of the Florida State Ilort. Society, Page 205, 1948. 2. METHODS OF ANALYSIS. Association of Official Agricultural Chemists. 6th Edition, 1945. ORNAMENTAL SECTION THE GENUS ALLAMANDA IN FLORIDA EGBERT S. REASONER Bradenton One of the most versatile of our Tropi cal American shrubs is the colorful Alla manda. Depending on its training, the Allamanda may be a shrub or a vine and is therefore logically called "Half vine Half shrub." Under good cultural con ditions the Allamanda should have flow ers in every month of the year. While this is a tropical plant and will not withstand freezing temperatures it does sprout readily from the roots and in a few short weeks following a freeze it will be a nice plant and full of bloom. Flowers are funnel-shaped, yellow or purplish in color, with the essential organs deep in the tube. The fruit is a large prickly cap. Fruit and seed are not borne on conservatory specimens and in Florida only Allamanda neriif olia or Bush Allamanda has the unusual seed pod with any regularity. With the exception of Allamanda neriif olia which is grown from seed, the other species of Allamanda are easily grown from old and new wood cuttings. With reasonable care a good grower should have a 90 percent live on cuttings. The Genus Allamanda is a popular one with the Landscape Architects and Gardeners because of its many uses. Allamanda cathartica, variety Hender sonii may be used as a spreading plant almost like a ground cover-two feet high and any desired spread from four feet up. This same variety may be trained as a vine although it must be tied as it has no devise for either holding on or attaching itself. The Williamsii variety may also be used this same way, but it is not as popular because of its smaller sized flower. The use of the Allamanda as a spreading type plant has come into more popular use recently with the more modern type of low home. Cer tainly one of the best assets of the Alla manda is its insusceptibility to insects and fungi. The following is a list of the species and varieties in the Genus Allamanda: ALLAMANDA (APOCYNACEAE family) Cathartica-Common yellow Allaman da; Brazil; scandent shrub Grandiflora--4 inch yellow flowers. Hendersonii-leathery, shiny foliage5 inch yellow flowers. N obilis-flowers to 5 inches across Magnolia-like fragrance. Schotti-three to four inch flowers, shorter and dark striped throat.

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180 FLORIDA STATE HORTICULTUHAL SOCIETY , 1950 Willi a m sii-3 to 4 inch flower with reddish brown throat, pubescent on un derside mid-rib. Double Flowering Sport of Willi a m s ii -2 to 3 inch double flowers, fragrant; cr inkl ed foliage same as Williamsii. Neriifolia Oleander Allamanda s hrub to three feet; leaves in whirls of 2-5 and to 5 inches J ong, dull green; Allamanda vio lacea golden yellow flower s 1 in ches across swollen at base; Brazil; foliage more narrow than Cathartica; does well in partial hade. V iol ac ea ( Purpurea ) -Purple A lla manda -s l ende r climber; le aves in 4's, ova l , to 6 in c h es l o ng; flowers 2 inches across of dusky-rose co l or, deeper in ce ter. Most rare of the Allamandas. Allamanda cathartica va r . H e nd e rsoni SOME ORNAMENTAL TREES AND SHRUBS NATIVE TO SOUTH FLORIDA GEO . D. R UEHLE Flor ida Agricultural Experiment Stat ions Sub-Tropical E xperimen t Station Homestead Th e ext r eme so uth ern portion of the Florid a peninsula contain an exten&ive flora that include s a remarkable va rie ty of plants. The n ative flora, particularl y of southea t Florida, includes a great m any s pecie s t h at belong esse nti a ll y to the tropical West Indian flora but in clude s also many plant s common l y found in central and north e rn Florid a. Among the nativ e plants found grow ing in the area a r e m a n y shrubs and trees with fo li age and flowers of s uffi cient beauty to make them good s ubje cts

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RUEHLE: ORNAMENTAL TREES AND SHRUBS 181 for ornamental landscape work. A few of these have attracted enough attention that they are being used rather exten sively in ornamental planting. Others have been planted in county parks, memorial parks and botanic gardens in recent years, affording an opportunity for more and more people to become ac quainted with native plants. Many others, however, that appear to possess horticultural value have been neglected and are either not cultivated at all or are found only in few of the larger botanic gardens. Very many exotic species have been introduced from the warmer regions of the world, and are grown extensively in southern Florida as ornamentals. The abundance of cultivated exotics diverts attention from the native flora, yet some of the native species are fully as attrac tive as many of the highly regarded exotics. A study was begun several years ago to evaluate as landscape subjects the many trees and shrubs native to the area. The area covered includes the Florida Keys, the Miami rock ridge, the Everglades Keys, and the coastal ham mocks, sand dunes and islands along the coast as far north as Palm Beach and Punta Gorda. The study is far from complete, but the following list contains some 66 species representing 33 plant families that are either being used as ornamentals or appear to be worthy of trial for this purpose. CYCADACEAE Zamia integrifolia Ait. Coontie, Flor ida arrowroot. PALMAE Roystonea regia (H.B.K.) 0. F. Cook. Royal palm, Cuban royal palm. Britt. Saw cabbage palm, Silver-saw palm. Sabal palmetto (Walt.) Todd. Cabbage palmetto, swamp cabbage, cabbage tree. Thrinax parviffora Sw. Green Pea berry palm, Thatch palm. Thrinax microcarpa Sarg. Silver Pea berry palm, Brittle Thatch palm. Coccothrinax argentata (Jacq.) Bailey. Seamberry palm, Florida silver palm. MYRICACEAE Myrica cerif era L. Southern wax myrtle, Bayberry, Myrtle. FAGACEAE Quercus virginiana Mill. Live oak. MORACEAE Ficus aurea Nutt . Florida strangler fig, Golden fig . Ficus brevifolia Nutt. Shortleaf fig, fig, Wild banyan. POLYGONACEAE Coccolobis laurifolia Jacq. Dove plum, Pigeon plum. Coccolobis uv i fera Jacq. Seagrape, Grape tree, Platterleaf. NYCTAGINACEAE Torrubia longifolia (Heimer) Britt. Blolly. MAGNOLIACEAE Magnolia virginiana L. Southern Sweetbay. ROSACEAE Chrysobalanus icaco L. Coco-plum. Prunus myrtifolia (L.) Urban. West Indian cherry, Laurel cherry. LEGlJMINOSAE Lysiloma bahamensis Benth. Wild tamarind. Acacia farnesiana (L.) Willd. Pithecellobium guadelupense (Pers.) Chapm. Blackhead. Pseudophoenix sargentii Wendi. SarErythrina herbacea L. gent cherry palm, Buccaneer palm, Hog ZYGOPHYLLACEAE cabbage palm. Guiacum sanctum L. Routhbark Paurotis wrightii (Griseb. & Wendi). lignum vitae.

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182 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 MALPIGHIACEAE Byrsonirna lucida (Sw.) DC. Locust berry. RUTACEAE Zanthoxylum fagara (~.) Sarg. Wild lime. Zanthoxylum coriaceum Rich. Biscayne prickly ash. SIMAROUBACEAE Suriana maritirna L. Bay cedar. Picrarnnia pentandra Sw. Bitterbush. Simarouba glauca DC. Paradise~tree, Bitterwood. Bursera sirnaruba (L.) Sarg. Gumbo limbo, West-Indian birch. Alvaradoa amorphoides Liebm. Alva radoa. MELIACEAE Swietenia mahogoni Jacq. Mahogany, West Indies mahogany. EUPHORBIACEAE Gymnanthes lucida Sw. Oysterwood, Crab wood. Drypetes laterifiora (Sw.) Krug. & Urb. Guiana plum. Hippomane mancinella L. Manchineel. AQUIFOLIACEAE /lex cassine L. Dahoon. Ile:r krugiana Loes. Southern holly, tawnyberry holly. CELASTRACEAE Maytenus ph11llantlwides Benth. Gutta percha mayten. Rhacorna ilicifolia (Poir.) Trelease. Christmas berry. SAPINDACEAE Sapindus saponaria L. Southern soap berry, soapberry. Exothea paniculata (Juss.) Radlk. Butterbough, Inkwood. RHAMNACEAE Reynosia septentrionalis Urban. Dar ling plum, Red ironwood, MELASTOMACEAE Tetrazygia bicolor tetrazygia. CANELLACEAE Cogn. Florida Canella winterana (L.) Gaertn. Canella, wild-cinnamon, cinnamon bark. GUTTIFERAE Clusia rosea Jacq. Balsam apple. COMBRETACEAE Bucida buceras L. Oxhorn bucida, Black-olive. Conocarpus erectus L. var. sericea DC. Silver buttonwood. MYRTACEAE Eugenia myrtoicles Poir. stopper, Gurgeon stopper. Spanish Eugenia confusa DC. Red stopper, Redberry eugenia, Ironwood. Eugenia simpsonii (Small) Sarg. Simpson stopper, Simpson nakedwood. Calyptranthes pallens (Poir.) Griseb. Spicewood, pale lidflower. ERICACEAE Pieris nitida B. & H. Fetterbush. Be/aria racemosa Vent. Tar flower, Fly catcher. THEOPHRASTACEAE J acquinia key ens is Nez. J oewood, Cudjoe-wood. MYRSIN ACEAE A rdisia escallonioicle.~ Sehl. & Ch. Rapanea guianensi.~ Aubl. Myrsine, Guiana rapanea. SAPOTACEAE Chrysophyllwn olivifonne L. Satin leaf. OLEACEAE Forestiera porulosa (Michx.) Poir. Florida privet. BO RAG IN ACEAE Cordia sebestena L. Geiger-tree. Bourreria ovata Miers. Bahama strongbark, Ovallleaf strongbark. Tournef ortia gnaphalodes R.Br. Sea lavender.

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REASONER: HIBISCUS SOCIETY 183 VERBENACEAE Callicarpa arn e ricana L. American beauty-berry, French mulberry. Duranta e pens L. Go ld en dewdrop, Pigeon berry, Creeping ky-flower. RUBIACEAE Strumpfia maritima Jacq. E1ithalis frnticosa L. Randia acul e ata L. Cliioco c ca alba ( L. ) A. Hitchc. S n ow berry. Royal Palms at H ornestead Sabal Palm e tto group, Fairch?ld 'I'1'opical Garden Hamelia patens Jacq. Scarletbush, Hamelia. Casasia clusia e folia ( Jacq. ) Griseb. Seven-year app l e. Sea Lavender, U. S. 1 Highway, lower keys Wild Tamarind tree, Woodlawn Park Cemete1y, M-iami THE AMERICAN HIBISCUS SOCIETY NORMAN A. REASONER Bradenton You will recall that when I had the pleasure of addressing this society last year on the subject of Hibiscus I men tioned the cry ing need for so me sort of an organization to act as a clearing house for the correction of Hibiscus nomenclature and the registration of new varieties. I am very happy, there fore, to be able to report that such an organization does now exist, under the name of The American Hibiscus Society, of which you r speaker has had the honor of being elected its first president. I do

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184 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 not believe I can give you a better ac count of the organization of this society and its aims than to repeat a portion of the minutes of our first meeting as so ably reported by our executive secretary, Mr. J. K. Brower. These minutes are as follows: "Following the successful staging of many Hibiscus bloom at the Hotel Bilt more at Palm Beach, Florida, on Sunday, May 21st, 1950, a group of enthusiastic people met in a room near the show area and organized the Florida Hibiscus Society. "Having served as Chairman of "Hi biscus Holiday" activities, Mr. J. K. Brower of West Palm Beach opened the meeting with the statement that many prominent personalities had long been expressing a desire for a Hibiscus Society and that this being the purpose of the called meeting, the first thing in order would be the selection of officers, which was done immediately. The fol lowing were elected officers for 1950: "Norman A. Reasoner, Bradenton, President; Harry Dunnaway, Fairchild Tropical Garden, Miami, Vice President; J. K. Brower, West Palm Beach, Execu tive Secretary; Albert Ingham, West Palm Beach, Assistant Executive Secre tary; E. Tinsley Halter, West Palm Beach, Treasurer. "The following Directors for 1950 were also named: "L. K. Thompson, Bartow; Jack 0. Holmes, Tampa; George L. Tabor, Glen St. Mary; Harry Grosser, West Palm Beach; Oliver C. Coffey, Miami; Dr. J. S. McKenzie, Miami; Niel Rhodes, Jackson ville. "The following objectives were then adopted, of which One and Two were deemed most important: "1. Standardization of H i b i s c u s names through our own nomen clature committee. 2 . Provide a clearing house for names of all varieties of Hibiscus. 3. Further development of possibili ties of our American Hibiscus Society. "The name of the Society, heretofore referred to as "Florida Hibiscus Society" was changed to AMERIC~N HIBISCUS SOCIETY effective at this first meeting, as so many requests were made for a broader coverage than Florida, to in clude those enthusiastic Hibiscus lovers from other areas." Following this organization meeting the society held its second show and business meeting at the Davis Islands Country Club on October 14, 1950, in cooperation with the Davis Islands Circle of the Tampa Federation of Garden Clubs. Some 3,000 bloom of over 400 varieties and 200 artistic arrangements were displayed at this show with some six or eight thousand visitors attending. At the business meeting w_e were finally incorporated as a non-profit organization and the following membership classifica tions were adopted: Participating members-annual dues, $3.00. Sustaining members-annual dues, $10.00. Contributing members-annual dues, $25.00 to $200.00. Patron members, those contributing $250.00 or more. Two other important actions were taken; the first, being the election of Mr. J. E. Hendry, of Ft. Myers and Mrs. Dora McGee, of Miami, to honorary membership in the Society with plaques to be presented to them in appreciation of their many years of meritorious serv ice to the Hibiscus world. The second important item of business was the adoption by the Society of the Hibiscus list prepared by your speaker as being the most authentic information

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REASONER: HIBISCUS SOCIETY 185 on nomenclature available up to this time. Please understand that neither I nor the other members of the nomenclature com mittee, who have worked with me on this, consider this fully and entirely correct! It is merely a starting place and will unquestionably be revised and extended as further information becomes avail able. Incidentally, your speaker and other officers of the Society will welcome any criticisms or information that any of you may be able to give us to bring this list more up to date. This list is being presented to every member of the Society, now numberin_g 210, from Hawaii, Puerto Rico, Alabama, Cali fornia, Louisiana, Texas, Arkansas, Rhode Island and all over Florida, as one of the benefits they will receive from their membership. This list may also be secured from the Reasoner organization for the price of $1.00, which just about covers the cost of publication. You will be interested to know that our third Hibiscus Show will be held in con nection with the Metropolitan Flower Show, in Miami, next March, with an other business meeting at that time. This about covers the history of the organization but in connection with my duties as President I have been privi leged to read various articles on Hibiscus, one of which is so very good that I should like to present it to this meeting and have it included in the proceedings of the Florida Horticultural Society where it may be preserved for ready reference by anyone who may wish to refer to it later. Unfortunately, our Hibiscus Society has no printed proceedings or public;ition as yet. This paper, which I wish to present, was an article on Hibiscus history written by Ross H. Gast, of Los Angeles, Cali fornia, one of the outstanding Hibiscus enthusiasts of that state and quite fami liar with the Hibiscm; situation in Hawaii. It is as follows: "~in.ce the first appearance of Hibiscus Rosa-Sinensis in English greenhouses over 200 years ago, there has always been a small group of plantsmen assidu ously striving to improve the flower. But as these men represented several generations, and even contemporary workers were often thousands of miles apart, there was little, if any, effort to coordinate findings and most of the work was unrecorded, thus lost forever. "For this reason, the organization of the American Hibiscus Society at Palm Beach last May was an important step, and the full development of its presently discussed program should have the un selfish support of all lovers of this exotic native of the tropical world. And un selfish is the word for success; both ama teur and commercial hibiscus growers must subject themselves unreservedly to the rules of the society if it is to succeed. "Too many of us are like the old Japa nese nurseryman, of Kalihi-kai, Honolulu. Whenever I questioned him as to the origin of a hibiscus variety, he always claimed it as his own. Finally I became suspicious and walked over to a large plant of common red, expressing surprise at the size and uniformity of the flower, and the magnificence of the foliage. I asked where he found his stock. 'Oh, I make him myself,' he replied proudly. 'Two, t'ree year 'go I make him.' "Of course, 'pride of parentage' can be exused up to a certain point-it has per sisted among plantsmen from time im memorial. There is ample evidence that William Bull, nurseryman of Chelsea, England, and Samuel Whitmore, of Ryde, Isle of Wight, who were hybridizing Hi biscus rosa-sinensis a hundred years ago, took in considerable territory in de scribing their introductions. Shortly after the turn of the century, W. M. Gif ford, of Honolulu, began to work with the flower, followed by U. S. Holt, G. P. Wilder, C. M. Cooke, A, Gartly, J, A.

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186 FLORIDA STATE HORTICULTURAL SOCIETY , 1950 Cummins, A. Koebele and others, sepa rately at first, but in 1911, with the for mation of the Hawaiian Hibiscus Society, as a group. The society did splendid work for several years, sponsoring an annual show, and, in the first year of its existence, strengthening the hibiscus breeding project established in 1909 by the Agricultural Experiment Station and the University of Hawaii. This group definitely proved that unselfish devotion to the best interests of their flower paid good dividends to all. "Unfortunately, both the Society and the Agricultural Experiment Station project became casualties of World War I -the impact of war on an insular com munity is much more severe than is the case generally. But while the records of the Society were not preserved, the Ex periment Station project resulted in the publication of the now rare Bulletin No. 29 "Ornamental Hibiscus in Hawaii," by E. V. Wilcox and U. S. Holt, in December, 1913. This publication lists, describes and gives the parentage of all known hybrids in Hawaii up to 1913, and names . 33 varieties introduced in Hawaii from other parts of the world. It also gives considerable background data on 14 na tive forms of Hibiscus, some of which have been used in the development of the now well known Hawaiian hybrids. "Since 1915, Hawaiian 'fans' have con tinued to improve the flower, but with out formal organization. Will Cooper carried out a rather large breeding proj ect at Cooper Ranch up until his retire ment a decade ago, and the late J. A. Johnson, of Honolulu, gave us some of our best hybrids of today. I was for tunate enough to work with this fine plantsman before his death in 1948, and seed from his crosses form the basis for most of the seedlings which I now con sider ready for commercial introduction, including the new 'Captain Eddie Rick enbacker' which will be featured in the fall and spring catalogues of Florida nurserymen. "In his will, Mr. Johnson gave his col lection, with sufficient funds to maintain it, to the University of Hawaii which is continuing his work. A ladies organiza tion, the Outdoor Circle, is sponsoring hibiscus shows occasionally. Mr. and Mrs. Willis Pope, of Waimanalo, Oahu, have a small breeding project under way, while A. B. Bush, of Kaneohe, and Bill Sutton, head gardener at the Royal Hawaiian Hotel, are still developing new varieties. It is not too much to expect that eventually all will see in the Ameri can Hibiscus Society a central agency for the collection and dissemination of data on Hibiscus Rosa-sinensis. "One of the first Society sponsored projects should be the development of a bibliography on H. Rosa-sinensis. In connection with my own work in hybrid izing hibiscus, I have tried to gather all reference material available, and I am now fortunate enough to have either in my own printed collection, or in form of notes and photostat copies a wealth of data on the flower. But there is citill a great deal of material yet to be compiled, both in this country and in England. "The principal reason for securing all historical and scientific data on hibiscus is that no sound breeding program can be carried out until we know more about the original plants as they were brought into Europe and America from their na tive habitat. At the present time, most of the hibiscus we grow are horticul tural varieties of unknown parentage, so that we cannot work with them with any planned result. Crossing hybrids may be fun, but such effort seldom results in any development of permanent value. "True, far more of the popular vari eties grown in both California ahd Flor ida than we suspect ate true species which have persisted because of their hardiness and commercial characteristics,

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TABER: WOODY PLANTS 187 such as ease of rooting, etc. An important part of my own project is the isolation and determination of what are true species, so that I can 'start from scratch,' so to speak, in my breeding program. This sort of thing should be aggressively sponsored by the Society, by the estab lishment, in Florida, of a project under authoritative direction, such as the horti cultural department of the University of Florida. "I have tried to determine which are true species by a study of such biblio graphy as is available, and by finding which varieties come true from seed. In connection with the former, many of the true species we grow now are pictured in color in English garden magazines pub lished a hundred and fifty years ago, and were accurately described in them. Such sources have been invaluable to me. "It may be of interest to many to learn that the first species of Hibiscus Rosa sinensis brought to England were doubles. In fact, the earliest mention of Hibiscus Rosa-sinensis that I have been able to locate is Van Rheede's 'Hortus Indices Malabaricus' published in 1678. This describes a pink double, and though the plate is not colored, it looks like our Kona. This species was native to the Malabar Coast, where many fine Hibi s cus were later collected for English greenhouses. The flower became a very popular 'stove plant' after its introduction in England about 1700. But as late as 1826, one writer says '-the double varieties of this species, crimson, yellow, buff, and even white are not uncommon in collections, but the single state ... although much handsomer, is comparatively rare.' "My own work is primarily designed to develop varieties of hibiscus sufficiently hardy to permit the enjoyment of this flower over a wider geographical range. This is being approached by crossing true species known to wi'thstand lower temperatures, and then selecting seed lings of good flower and foliage char acteristics for further crossing. Ease of growing on their own roots and resist ance to cold, wet soil are also factors that are being sought. "The work is discouragingly slow, but with the development of the Society program, I feel that I, as well as others, interested in hibiscus can look for real assistance.'' INTERESTING USES OF WOODY PLANTS GEORGE L. TABER Glen St. Mary For many years my father was active in this organization and always was vitally interested in it up to the time of his death in 1929. Unfortunately for me, my association with the group has not been too close. I sincerely hope, however, that this situation will be changed for the future. I am honored to be included in your programme, but I must warn you that this is not a learned dissertation-merely a few simple ideas on interesting uses of woody plants that anyone may use if he chooses. In striving for the unusual, one must always be watchful against becoming over-zealous in that direction. While it is certain that by far the majority of landscape plans are stereotyped, run-of the-mill job s , the small percentage that do not fall into this classification are liable to searching scrutiny-just because they are different. Suppose then that we consider the in teresting uses to which some of our well

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188 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 known woody plants may be adapted without, let us hope, straining the capa bilities of the subject or the credulity of the audience. For example; we are most of us familiar with Pyracantha (Firethorn) which is, incidentally, aptly named, as anyone who has ever been in close con tact with one can testify. Although the Pyracanthas are generally used in foun dation planting or as specimens to give fall and winter color elsewhere on the premises, they can also be starred in an other and quite different role. Trained flat and precisely patterned against a wall in espalier or spreading fanwise on a specially built support, they are both unusual and beautiful. Roses too, at least some of them, are amenable to treatment of this sort. Especially striking are the standards and pillar roses, some of them trained to three-pronged spreading trellises, so lavishly employed by our California neighbors to confound, with the aid of ' their continuously unusual climate, us less fortunate travelers from "Back East." Some might fail to see the con nection between Pyracantha and roses but, oddly, they are both of the Rosaceae family. And, while speaking of roses, why do most of us plant them in beds, angular and unimaginative? Habit most ly, but certainly not from any cultural or horticultural necessity. Roses, particu larly those increasingly popular little Floribundas and Polyanthas, lend them selves admirably to dotting around in the foundation planting for spots of color as well as for the more obvious use against a low wall or fence. There are many fine varieties that offer a challenge to the homeowner's imagination and ingenuity. Fashion, Donald Pryor, and Mabelle Stearns are excellent shrub roses for that kind of planting. Most of us know and like Crape Myrtle with its gay summer blooms in red, pink, purple and white, but I'll venture to say that unless you have been to Jamaica in the West Indies and stopped for a de lightful interlude at Castleton Gardens near Kingston, you have never seen them handled as a bedding plant. Here is the procedure: Small Crape Myrtle plants are set in beds or edgings, usually to tie down a taller planting. They bloom prodigiously at a height of eighteen inches or so and when their flowering period is over (early fall and winter here) they are taken up, their tops and roots pruned back fairly hard, and heeled in for the winter in some suitable out-of~ the-way area. In early spring before growth starts, the plants are removed from the storage area and replanted in their original positiont to thrive apace and bloom once more. While the Crape Myrtles are resting, other seasonal plants may be put in the beds, thus providing an unbroken succession of color all year round. Incidentally, the Crape Myrtles can be grown or trained to standard form quite easily. In tree shape with symmetrical heads our lowly shrub takes on a new dignity that fits it for more formal uses. There is another of our southern flow ering shrubs, dear to the hearts of count less authors writing ante-bellum ro mances-the ubiquitous Oleander. It is doubtful if a heroine of those poignant tales ever dallied, with many a sigh, 'neath the gracefully spreading branches of an Oleander tree while fearfully whis pering-"He loves me, he loves me not," as the little pile of bright hued petals grew larger on the grass beside her. It can be done, however, and modern maidens may easily have the opportunity of utilizing the Oleander's shade if some~ one has had the foresight to do a little trimming and training. Fortunately>the Oleander is quite easily persuaded from its more common bushy habit and the results that can be attained are well worth the effort.

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TABER: WOODY PLANTS 189 Of course we must consider Azaleas, although somewhat fleetingly, as so many dissertations have been made on them and so many assertions made about them already. I have seen Azaleas of many kinds used in strange and wonderful ways and places, but perhaps some of you "Green Thumb Boys" who like to putter around with plants will get more pleasure out of topworking a strong growing variety like Formosa or Elegans with a multivariety grown. _ It may be done by the use of ordinary whip grafts placed in the stubs of the Azalea's original head, the idea being to see how much of a bouquet you can produce and how quickly. Some beautiful combinations could be achieved but on the other hand it is _ con ceivable that a mixture somewhat less than aesthetic might evolve! Most of us are more or less familiar with Sasanqua Camellias and know in a vague sort of way that they possess cer tain advantages not inherent in Camellia Japonica. Do we realize though that these remarkable plants are not only superb, early flowering shrubs for in cidental placement in the garden or land scape plan, but are also easily converted to make grand hedges? Their compara tively fast growth and full-foliage habit, coupled with a truly noteworthy toler ance in regard to soils and soil moisture, recommend them for the gardener or even the rank layman who is anxious to try something new. As with Camellia J aponica, the Sasanqua cannot be suc cessfully grown everywhere in Florida, but at least its likes and dislikes are much less pronounced. I do not want to sound like a nursery catalog, however useful they may be in their place, but in the Genus Camellia there are two shrubs similar yet quite different from the species just mentioned. The first is Camellia Thea, which, at fiirst glance is not startling in appearance, al though presenting an attractively fresh green color and form. But, for those devotees of the English national drink, the brew made from its new tender leaves, adequately parched and simmered, is shall we say "Just a bit of all right, by jove!" In short, the tea plant of com merce has found its way from India and Formosa and now is available to us for tunate ones in the South, both as an eminently satisfactory evergreen shrub and as the makings of a refreshing thirst-quencher. The second of these Camellia cousins is Cleyera J aponica. It is, besides being a most attractive plant, one of the few, if not the only one I can think of, that is virtually fool-proof as woody plants go, and also almost bug-proof, in our experi ence at least. (If anyone would like to take execption to either of these state ments, please feel free to do so when I'm through.) This amazing evergreen shrub seems to thrive on adversity and I have yet to see one killed or even materially damaged by too much water or a super abundance of dry weather. We, at Glen Saint Mary, have come to look upon _ the Cleyera as practically invincible within its adapted range and are apt to recom mend it for the distraught homeowner who is beset with more than the usual number of plant troubles. There is no really unusual way to handle a Cleyera you just plant it and it grows-not like Jack's Bean Stalk nor yet the Green Bay Tree, but only in its own interesting, de pendable way. The chief claim to the fame of Cleyera lies not in versatility of treatment, but in the mere fact that it can survive and thrive in so many unlike ly places. In bringing to an end this potpourri of horticultural observations, may I leave this thought with you? Simplicity, after all, is the best policy and can usually be attained if one works at it-frequently it does not come easily.

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190 FLORIDA STATE HOHTICULTURAL SOCIETY, 1950 SOIL STERILIZATION H. N. MILLER Florida Agricultural Experiment Station Gainesville Florists, nurserymen, home gardeners and others who try to grow plants soon er or later encounter one or more soil borne organisms which cause "damping off" of seedlings and cuUings, reduces vigor, or causes death of the plants by destroying the roots. Some of this trouble can be avoided by changing soil or moving to a new location. However, this is not always feasible or satisfactory. The steaming of soil has been prac ticed in greenhouses for many years and has been used more than any other method for soil sterilization. However, this method is expensive and not always practical unless facilities for steaming are available. Many chemicals have been and are be ing tested for soil sterilization with varying degrees of success. Regardless of the method or material used certain precautions must be taken if the desired effect is to be obtained. The operation must be done thoroughly. If heat or steam is employed it is essential that all parts of the soil reach a temperature of at least 140 F. This temperature should be maintained for a period of two hours to assure killing of all soil-borne disease producing organisms. If chemicals are used they must be applied in such a way that all parts of the soil are reached by the chemicals. In any case, after the treatment has been done caution must be taken to prevent recontamination. . Be~s, flats and propagating benches must be cleaned and disinfected before they are filled with fumigated soil. This can be accomplished by scrubbing the benches with a solution of formaldehyde or other good fungicide. Tools should be disin fected by dipping them in a solution such as formaldehyde. Pots and plant con tainers can be disinfected by dipping in formaldehyde. This solution is made up at the rate of 1 part commercial formalin to 49 parts water. There are several materials which can be used as soil drenches to sterilize soil before planting or to minimize the in cidence of damping-off of seedlings or cuttings. Formaldehyde has been used for some tiine as an effective soil drench. A solu tion of 1 gallon of formalin diluted in 50 gallons of water and applied at the rate of 1 gallon per square foot of soil is ef fective in destroying many soil-borne disease-producing fungi. The soil should be loosened before application of the material. After treatment the soil should be covered with canvas, boards or paper and left for 24 hours, then allowed to dry until all odor of formaldehyde has dis appeared from the soil. Some of the commercial fungicides can be used as soil drenches to lessen the effects of damping-off in seed beds, flats, and cutting benches. These materials are made up in solution and poured on the soil around the plants. Spergon or Ferbam used at the rate of 2 ounces in 3 gallons of water has been effective in re ducing "damp-off." The Coppers and Mercury compounds can be used, how ever, they may be injurious to some plants and should be used with caution. Soil drenches are usually only partially effective and should not be relied upon where complete control is desired or where severe disease problems are ex pected . A number of volatile chemicals have been introduced within the last few years which have shown varying degrees of success as soil fumigants. The mate rials kill by means of volatile gases or water solutions which penetrate several

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l\HLLEll: SOIL STEIULIZATION 191 inches from the point of injection or place of application. Since most of these materials contain substances which are toxic to plants they have to be used from one to several days before planting or setting of plants can safely be done. Most of the volatile materials are only effective against nematodes and to a lesser extent against the fungi which cause damping-off and root rots. The principal fungants which are available at the present time are Chloropicrin, DD ( mixtures of dichloropropane and dichlo ropropene), ethylene dibromide and methyl bromide. The fungicidal and nematicidal prop erties of Chloropicrin are well known. When injected into the soil it will kill fungi, nematodes, insects and weed seed. At present probably no other fu:nigant surpasses it in fungicidal properties. However, Chloropicrin has several draw backs which limit its use. It is expen sive. It is highly phytotoxic and cannot be used near growing plants. The vapor kills foliage as well as plant roots. If Chloropicrin is used in a greenhouse or enclosed space all growing plants must be removed from the area. To insure kill, after chloropicrin is in jected into the soil, a seal is necessary. Usually this consists of sprinkling the soil surface with water. The gas is in soluble in water and a water seal will keep the gas from escaping. In fumigat ing potting soil, a gas tight bin or gas proofed canvas or paper covel' can be used. "DD mixture" has been shown to be just as effective against nematodes as Chloropicrin, and is a great deal less ex pensive. However, it has little effect on fungus diseases. DD has several advan tages as a nematicide. It is less objec tionable to use than Chloropicrin. The material remains in the soil for some time and a water seal is not necessary. While the material cannot be used around living plants the escaping fumes are not particularly toxic to the foliage of plants growing nearby. It can be used in green houses without injury to plants in the house provided there is adequate ventila tion. Since DD remains in the soil for some time two to three weeks may need to elapse before the treated soil can safely be used. This depends a great deal on the temperature and moisture content of the soil. . There are several commercial soil fumi gants on the market which contain vari ous amounts of ethylene dibromide. Al though these materials are not effective fungicides they are among the cheapest soil nematocides and insecticides now available. Ethylene dibromide persists in the soil for some time and a seal is not ffecessary. The commercial mixtures are not objectionable to handle. However, ventilation should be provided and the fumes should not be breathed. In this group of materials there is one form which should be of especial interest to the home gardener and the small grower. It is a capsulated form of ethylene dibromide and is sold under the trade name of "Soilfume-Caps." The fumigant is embedded in gelatin pellets. This material would probably be expen sive to use on a large scale, but where small areas are to be treated the con venience in handling the material offsets the added expense. For flower beds, small plots and areas where shrubs and other plants susceptible to root knot are to be planted, the soil can be easily treated with "Soilfume Caps" for the control of nematodes and wireworms. It is recommended that the soil be treated once a year prior to planting. Holes are made in the soil four to five inches deep and spaced twelve inches apart. One capsule is placed in each hole, the hole filled and the surface packed firmly. Under ideal conditions, a minimum of two weeks should elapse

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192 FLORIDA STATE HORTICULTURAL SOCIETY, 1950 between treatment and planting. The material should not be used near grow ing plants, particularly if the roots of nearby plants are growing into the area to be treated. This material is effective for treating an area where a root-knot infested shrub has been removed and a replacement is desired. Dowfume MC-2, a mixture of Methyl bromide and two percent Chloropicrin, is one of the most effective soil fumigants available and is particularly adapted to use of the nurserymen and the home gardener. It finds its greatest useful ness in the treatment of seed beds, potting soil, benches, and ground beds of green houses. MC-2 has been used for some time as a space fumigant to eliminate insect pests from nursery stock. As a soil fumigant it controls nematodes, cer tain soil fungi, weed seeds, and insects. It can be used within a foot of many growing plants without injury to their roots. MC-2 is marketed in sealed cans and must be applied by means of a "jiffy" applicator and injected under a gas tight cover or into a sealed chamber. Soil to be treated should be worked in a fine, loose condition and should be neither too wet or too dry. It is covered with a gas-proof canvas or paper. The central area of the cover is supported 12 to 18 inches above the soil. The edges of the paper are then pulled down to the ground or floor and covered with soil. The volatile liquid is released through a special tube into a trough or shallow pan placed on top of the soil under the cover. There are some disadvantages to MC-2. While no complicated or expensive equip ment is needed, a special applicator with sufficient tubing and a suitable gas-proof cover are needed. The material is very toxic to man, and extreme care must be taken in its use. Complete directions for the use of MC2 together with the necessary material for application can be obtained through the MC-2 dealer. GREENHOUSE FOLIAGE PLANTS IN FLORIDA PETER PEARSON Plymouth For introduction to this article, I should say I was first introduced to the State of Florida at the Pageant of Progress in Chicago in 1933-1934. I had been buying some Sansevieria from one of the growers in Apopka. That was about the only plant I could get with the exception of Boston Ferns. In December of 1934 I decided to make a trip to Florida for the purpose of in vestigating possible sources of other plant material. I arrived in Apopka in December 1934, then known as the Fern City. (I think now it should have a more appropriate name to embrace a larger field of horticultural products.) On my trip around the nurseries, I did not find much of a selection in plants, but I did find a delightful climate, remark ably suited to growing most of the decorative green plants that are used in the Northern part of the United States for indoor decoration and sold by the Northern retail florists. I was surprised that so few had discovered these advan tages offered in Florida; but since the Florida growers have become acquainted with the possibilities in the Northern markets, rapid strides have been made in this branch of horticulture. As late as 1937, there was but one small green house in the Apopka section. Today there are 200,000 feet of glass houses, around Apopka and Plymouth, devoted to production of this class of plants in

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PEARSON: GHEENIIOUSE FOLIAGE PLANTS l! X