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5HUMi L 1RY
!.F.AS. U :. of FloriT
Anniversary 193171981
Agricultural Research Center, Leesburg
University of Florida/Institute of Food and Agricultural Sciences
50th Anniversary 1931/1981
Agricultural Research Center, Leesburg
University of Florida
Institute of Food and Agricultural Sciences
Leesburg, Florida 32748
The Agricultural Research Center, Leesburg,
is located in Lake County, 6 miles south of
Leesburg on U.S. Highway 27.
Editor: Chuck Woods
Graphic Designer: Ralph Knudsen
History
IIIII i I IIII I I I
The Leesburg Field Laboratory was
established by the 1929 Florida leg-
islature as a branch unit of the Ag-
ricultural Experiment Stations of the
University of Florida, primarily to
conduct research on disease and in-
sect problems of watermelon. Two
watermelon diseases, Fusarium wilt
and anthracnose, were threatening
to destroy the state's thriving wa-
termelon industry (approximately
30,000 acres), which was then
centered in the Leesburg area. In
addition the Laboratory was com-
missioned to study the insect pests
and diseases of ferns and ornamen-
tals, also grown extensively in cen-
tral Florida.
The 1931 Annual Report of the
Florida Agricultural Experiment
Stations reported as follows: "At
Leesburg... the Board of Control
authorized the acceptance of land
offered by the local people as a site
for the laboratory ." The original
laboratory was located near the east
city limits of Leesburg in a 2-room
frame building containing a labora-
tory and office. At this site there
was also a greenhouse (presently used
at the new Center location), a stor-
age shed, and screenhouse. The
laboratory building was heated with
a pot-bellied stove during the win-
ter until a central hot-water heating
system was installed in 1950.
Salary and expense appropria-
tions for the Watermelon and Or-
namental Laboratory were $15,000
in 1929-30, $10,000 in 1930-31,
and only $8,558 the following two
years when both banks closed in
Leesburg. Appropriations for the
Watermelon Investigations Labora-
tory, as it was called during the mid-
and late-1930's, was boosted by a
separate $3,500 annual appropria-
tion for grape pest research begin-
ning in 1933-34. This was sparked
by efforts of the Florida Grape
Growers Association, which sent
three people to Tallahassee to re-
quest help for Florida's diseased
vineyards. By 1940-41 the appropri-
ation for watermelon research was
$10,000 and for grape $3,500. The
two were combined in 1941-42, and
the name Watermelon and Grape
Investigations Laboratory was
adopted. The war-time 1944-45
budget jumped to $20,915, and the
name was changed to Watermelon,
Grape, and Sea Island Cotton In-
vestigations Laboratory. In 1948,
with no further cotton work under
way, the prior name, Watermelon
and Grape Investigations Labora-
tory, was used once again. In 1971
this unit of the Institute of Food and
Agricultural Sciences was desig-
nated the Agricultural Research
Center, Leesburg.
A 77-acre research farm was orig-
inally located 5 miles west of Lees-
burg near the town of Whitney.
Facilities at the farm included an
equipment storage and garage build-
ing, a screenhouse, and a hand pump
well.
By 1952 the Whitney farm land
was no longer suited for producing
watermelons. Repeated and inten-
sive cropping of watermelons had
caused a buildup of nematodes,
weeds, and soil fungi, including the
fungus causing wilt. It was neces-
sary to rent land adjacent to the
Whitney Farm for field research
to continue.
Because of these problems a search
for a new research farm and labora-
tory site was begun in 1955. In April
1958 the entire physical facilities of
the Laboratory were moved to 6
miles south of Leesburg on U. S.
Highway 27. At this location a 163-
acre research farm and a separate
2-acre laboratory site were situated.
The office-laboratory building
constructed thereon, overlooking a
picturesque lake, includes 5 office
rooms, 3 storage rooms, and 2 lab-
oratories. A headhouse building with
two greenhouses has also been built
at this site. Another 2 acres adjoin-
ing this property were added in 1972.
The physical facilities of the re-
search farm include a large equip-
ment and storage bam, a tool storage
and machine shop building, two
screenhouses, a 10-inch well for ir-
rigation, and several other small
buildings. Approximately 100 acres
were added to the 163 acres in 1972,
for a total of 262 acres on the pres-
ent research farm.
Three different plant pathologists
have had responsibility for the lead-
ership of the research program and
operations of the Agricultural Re-
search Center, Leesburg, from 1929
to the present: Dr. M. N. Walker
(Nov., 1929 thru June, 1942), Dr.
G. K. Parris (Feb., 1945 thru June,
1951), and Dr. J. M. Crall (Oct.,
1952 thru 1977). Other plant pa-
thologists at the Center were Dr.
W. B. Shippy (1929-1937), Mr. K.
W. Loucks (1929-1943), Dr. N. C.
Schenck (1956-1969), and Dr. D.
L. Hopkins (1969 to present).
Entomologists at the Center were
Mr. C. C. Goff (1930-1939), Dr. J.
W. Wilson (1930-1937), Dr. W. C.
Adlerz (1958 to present), and Dr.
C. H. Curran (1961-1971).
Horticulturists included Mr. L.
H. Stover (1941-1965), Dr. C. F.
Balerdi (1966-1972), and Dr. G.
W. Elmstrom (1969 to present). Dr.
Elmstrom was appointed Center Di-
rector in 1978.
Geneticists were Dr. J. G. Buch-
ert (1959-1960) and Dr. J. A. Mor-
tensen (1960 to present).
Agronomists included Dr. E. E.
Hartwig (1942-1943), Mr. C. G.
Helms, Jr. (1950-1955), and Dr. H.
A. Peacock (1957-1958).
The Laboratory had no faculty
stationed at Leesburg after the res-
ignations of Mr. K. W. Loucks and
Dr. E. E. Hartwig in February, 1943.
Mr. Loren H. Stover, farm foreman
at that time, oversaw the research
program and budget until the arrival
of Dr. Parris in February, 1945. Mr.
Stover became an official staff
member when he was promoted to
assistant in horticulture in July, 1951.
MISSION AND GOALS
Fruit Crops. The Leesburg cen-
ter serves as the primary resource
center for the developing grape and
wine industries in Florida. A major
goal of this center is the develop-
ment of cultivars, cultural practices,
and pest controls to enhance the
establishment of these industries.
Responding to the needs of both
commercial vineyardists and home
gardeners is the mission of this cen-
ter in the fruit crops area. Major
emphasis is placed on the under-
standing and control of Pierce's dis-
ease (PD) of grape, a disease caused
by a rickettsialike bacteria; this en-
tails studies on the etiology, epide-
miology, physiology of resistance,
and control. The role of the PD
bacterium in other diseases such as
young tree decline (citrus blight) is
also being investigated.
A secondary goal in the fruit crops
area is the identification of cultivars
and breeding lines of peaches, ap-
ples, blueberries, and blackberries
suitable for growing in central Flor-
ida. This will be accomplished by
the evaluation of releases and clones
from breeding programs at other lo-
cations, principally Gainesville.
Vegetable Crops. This center has
statewide responsibility for research
on cucurbits, which include water-
melons, cucumbers, squash, and
muskmelons. A major goal is the
development of watermelon culti-
vars of various sizes and shapes with
resistance to the diseases of water-
melon, high quality eating charac-
teristics, and desirable shipping
characteristics. Control of Fusarium
wilt of watermelon and develop-
ment of an integrated control sys-
tem for the watermelon "old land"
problems are other important goals.
Development of FI muskmelon cul-
tivars and identification of cucurbit
breeding lines and recently-released
cultivars that are superior to the
cultivars currently being grown in
Florida are other important areas of
research.
RESEARCH
PROGRAM AREAS
Fruit Crops. The primary, long-
range objective is the development
of new bunch and muscadine grape
cultivars that are marketable, pro-
ductive, and long-lived in Florida
through planned hybridization. Im-
proved cultivars are needed for fresh
fruit, wine, and juice. Early and late
maturation of cultivars is important
to expand the harvest season. Seed-
less cultivars would be beneficial for
table grapes and raisins. Finally, re-
sistance to fungal diseases and root
feeding insects is of utmost impor-
tance.
Short-term objectives in this area
of research are release of grape
breeding lines that are superior to
current cultivars. Release of a grape
rootstock superior to the rootstocks
currently available is another short-
term goal. Finally, a continuing
program is the identification of
peach, blueberry, apple, and black-
berry cultivars and breeding lines
adapted to cultivation in central
Florida.
Another major, long-range goal
is the chemical or biological control
of Pierce's disease (PD). An under-
standing of the epidemiology of this
disease might lead to a control
II L
method. Incorporation of genetic
resistance into superior cultivars is
a second possibility for control. In-
cluded in the short-term goals to be
accomplished in this area of re-
search are:
A. Understanding the virulence
and serology of various isolates
of PD from around the state:
including studies on toxin pro-
duction, multiplication, and
movement in the plant.
B. Control of PD with antibiot-
ics.
C. Development of a procedure
for screening grape seedlings
for resistance. More informa-
tion is needed on stage of
growth for screening, inocu-
lum concentration, and method
of inoculation.
D. Feasibility of controlling PD by
limiting vectors and/or wild host
plants. The difficulty of rear-
ing leaf hoppers is a major ob-
stacle in completing needed
transmission studies.
E. Determining whether or not a
link exists between PD and
young tree decline (Citrus
blight).
A third major long-range goal is
maximizing the efficiency of grape
production in Florida. In other
words, developing an integrated
crop management system for grapes
in Florida. Goals include:
A. Determining fertilizer and
water requirements of the
plant, and finding the best
pruning and trellising systems
for Florida grapes.
B. Control of grape root borer
through chemical or biologi-
cal (genetic) mechanisms.
C. Improved control of grape
diseases and insects. Revising
disease and insect control
recommendations as new,
more effective chemicals be-
come available. More infor-
mation is needed in timing of
application and method (type
of sprayer) of application.
D. Improvement in grape fruit set
and cluster size. Reducing the
amount of dry calyptra in both
bunch and muscadine grapes
might be possible with plant
growth regulators.
E. Reduction in the amount of
wet stem scar in mechanically
harvested muscadine grapes.
Ethrel and similar ethylene
releasing materials have shown
promise for this use.
Vegetable Crops. Cultivar im-
provement is an ongoing, long-
range program to develop and/or
identify cucurbit cultivars superior
to those currently under cultiva-
tion in Florida. Short-term goals
in this area include:
A. Identify the breeding lines and
recently-released cultivars that
are superior to those currently
recommended and grown in
Florida. Seed companies are
encouraged to release and
name numbered lines that are
superior in trials at Leesburg.
B. Incorporation of high-type
Fusarium wilt resistance into
the commercial watermelon
cultivars 'Charleston Gray'
and 'Jubilee'.
C. Release of an 'ice-box' melon,
8-15 lb., with high quality,
suitable for production in
Florida and for shipping in
cartons to domestic and over-
seas markets.
D. Development of a standard
inoculum for use in green-
house screening for Fusarium
wilt resistance in waterme-
lon.
E. Release of F, muskmelons for
which seed can be produced
without emasculation and
hand pollination. This in-
volves the incorporation of the
monoecious or male sterile
flowering habit into a parent
line.
F. Development of bush type
(short internode) watermelon
and muskmelon plants to in-
crease yield and efficiency of
production.
G. Development of F, hybrid
watermelons, now feasible
with the availability of di-
verse germplasm with resist-
ance to Fusarium wilt.
Cucurbit disease and insect
control is a second long-range goal
in this area. Important cucurbit
diseases are Fusarium wilt (water-
melon), mildews (watermelon,
squash, muskmelon), watermelon
mosaic virus (all cucurbits), and
gummy-stem blight (watermelon,
muskmelon).
IIIIL I II I
Insects important on cucurbits
include aphids, pickle worms, cut-
worms, mole crickets, and rind-
worms. Some of the short-term
goals in this area are:
A. Fusarium wilt
1. Evaluate methods of con-
trol for effectiveness and
cost.
2. Develop biological control
methods or options in-
cluding genetic resistance,
competitive soil orga-
nisms, mulches, and crop
rotation.
B. Watermelon mosaic virus
1. Epidemiological studies on
the virus including trans-
mission and virus reser-
voirs in the wild host plants
is ongoing.
2. Use of repelling oils is being
studied.
3. Genetic resistance is avail-
able for watermelon,
muskmelon, and squash.
Inheritance studies are
needed as are studies on
the mechanisms) of re-
sistance.
C. Mildews and gummy stem
blight
1. Evaluation of new chemical
control materials and meth-
ods. The work involves
evaluation of materials and
residue studies as needed.
2. Incorporation of disease and
insect resistance from resist-
ant plants of the same spe-
cies or closely related species.
Since viable seeds are not
always produced from these
latter crosses, this work
might involve genetic engi-
neering and ovule or em-
bryo culture techniques.
Cultural Practices. A final long-
term goal is the development of cul-
tural practices for cucurbits which
conserve fertilizer and water and
maximize yield.
PRIORITY
RESEARCH
PROGRAM AREAS
Of those program areas discussed
above, those that will receive spe-
cial emphasis in the 1980's include
the following:
1. Grape breeding and cul-
tivar development
2. Cucurbit breeding pro-
grams
3. Pierce's disease/Citrus
Blight studies
4. Control of Fusarium wilt
of watermelon
RESEARCH THEME
FOR THE 1980's
The research program for the
1980's will be involved with in-
creasing the efficiency of Florida's
agriculture, especially in the fruit
and vegetable crop areas mentioned
previously, to insure that Florida will
remain competitive with other geo-
graphic areas.
Agriculture in Florida is energy
intensive; crops produced in Florida
require more fertilizer, water, and
pesticide than crops grown in most
other areas of the United States. If
Florida is to remain competitive
while energy resources are shrinking
and costs are escalating, the most
efficient means of food production,
processing, and handling must be
determined and utilized. The en-
ergy components of production sys-
tems will be of primary concern when
research is planned, conducted, and
evaluated.
Agriculture in Florida will con-
tinue to be diversified and perhaps
even more so. Inhibitory transpor-
tation costs will provide impetus for
production of crops not currently
under cultivation in the state. The
varied expertise of the faculty at
Leesburg makes possible a systems
approach to problem solving. An
integrated crop (pest) management
approach will be used in studying
efficiency of production of both
grapes and cucurbits.
I
Fifty Years of
Watermelon Breeding Research
By Dr. J. M. Crall
In 1930 a tract of land was leased
near Leesburg and 104 varieties were
planted on 10 acres that had been
planted in watermelons three times
in the previous 11 years. Most of
these plants died from Fusarium wilt,
but seed from the survivors were
planted in 1931 and the first crosses
were made on them that year. Em-
phasis in the early years of the pro-
gram was on resistance to Fusarium
.wilt, and many crosses and selec-
tions were made with the object
of developing new wilt-resistant
varieties.
One of the most fortuitous crosses,
'Hawkesbury WR' x 'Leesburg,' was
made in 1936. Selections from this
cross were made available to many
watermelon breeders. One of them,
designated Florida seedling 124, has
been recognized as the source of high-
level resistance to wilt in 'Calhoun
Gray,' 'Summit,' and 'Calhoun
Sweet.' Four other cultivars with
high-level resistance to wilt
('Smokylee,' 'Verona,' 'White-
hope,' and Texas W5) also have
'Hawkesbury' and 'Leesburg' in their
genealogy. In 1936 anthracnose-re-
sistant breeding lines were acquired
and incorporated into the breeding
program. Lines incorporating an-
thracnose and Fusarium wilt resist-
ances in horticulturally desirable
types were widely distributed to other
breeders, so that Florida lines are
found in the genealogy of many of
the watermelon varieties currently
grown in this country and through-
out the world. From these begin-
nings, the watermelon program at
Leesburg has continued to the pres-
ent time, with additional goals added
from time to time. Important goals
over the years have been the devel-
opment of varieties producing high
yields of early maturing melons with
desirable eating and shipping quali-
ties on vigorous vines with multiple
disease resistance (including resist-
ances to Fusarium wilt, anthrac-
nose, downy mildew, watermelon
mosaic, and gummy stem blight).
BREEDERS AND
CULTIVARS
The Florida breeding program was
begun at Leesburg in 1930 under
the guidance of Marion N. Walker.
He resigned in 1945 to assume du-
ties with the U.S. Department of
Agriculture. Walker was succeeded
by G. Keith Parris, who conducted
the breeding program until 1951.
The author assumed leadership for
watermelon breeding in 1952 and
has continued in that capacity until
the present time. Seven water-
melon cultivars have been released
during the 50-year program
(Table 1).
Table 1. Watermelon cultivars developed from 50-year breeding program at ARC Leesburg.
Release Description Seed Disease
Cultivar date of fruit color resistance' Parentage
Leesburg 1936 Long, solid green White WR Kleckley Sweet
Blacklee 1944 Long, solid green Black, stippled WR Leesburg, Hawkesbury
Ironsides 1950 Long, solid green Black, stippled WR Leesburg, Hawkesbury,
Garrison
Jubilee 1963 Long, striped green Black, stippled WR, AR Africa 8, Iowa Belle,
Leesburg, Hawkesbury,
Garrison
Smokylee 1971 Long, solid green White WR, AR Texas W5, Charleston Gray
Dixielee, 1979 Round, striped green Black, stippled WR, AR Texas W5, WR Peacock 132,
Summit, Fairfax, Graybelle
Sugarlee 1981 Round, striped green Black, stippled WR, AR Texas W5, Summit,
Charleston Gray, Fairfax,
Crimson Sweet, WR Graybelle
'WR, wilt resistant; AR, anthracnose resistant.
Jubilee (1963)
IMPORTANT
BENCHMARK DATES
SINCE 1952
1952-61. This period was one of
evaluation of materials on hand from
previous breeders and searching for
accessions that might have value for
future breeding purposes. During this
period 10 accessions from the U.S.
Regional Plant Introduction Sta-
tion at Experiment, GA and several
lines from the Dominican Republic
with purported resistance to downy
mildew were found to be susceptible
to this disease. Also during this pe-
riod, nine segregating progenies re-
lated to 'Garrisonian' were obtained
from C. F. Andrus of the South-
eastern Vegetable Breeding Labora-
tory at Charleston, S.C. The cultivar
'Jubilee' was developed from these
lines after four generations of selec-
tion on soils heavily infested with
the Fusarium wilt fungus.
1961. The development in 1960-
61 of a reliable greenhouse testing
procedure, using soil inoculum for
infestation and seedling wilt as a
criterion of Fusarium wilt resist-
ance, led to a major change in the
watermelon breeding program here.
Using this procedure, we were able
to identify a high-level resistance in
the cultivar 'Summit,' and later also
in Texas W5, 'Calhoun Gray,'
'Calhoun Sweet,' 'Verona,' and
'Whitehope.' First crosses were made
in 1961 to combine this high-level
resistance to Fusarium wilt with
anthracnose resistance (race 1) and
other characters desirable in a
I -
high quality shipping-type water-
melon. 'Smokylee,' 'Dixielee,' and
'Sugarlee' were developed from
this program.
1962. Because of interest on the
part of Florida growers and shippers
in new varieties and numerous in-
quiries from them about the adapt-
ability of the 'Klondike' and 'Peacock'
cultivars grown commercially in
California, we acquired a number of
accessions of these types in the pe-
riod 1962-64. None of them proved
to be adapted to our conditions, but
crosses made in 1962 to a wilt-re-
sistant Peacock type led to the in-
corporation of an intense red flesh
color and crisper-firmer flesh tex-
ture into many of our breeding lines.
These two characters, along with
small black seeds and higher soluble
solids juice, are some of the most
important improvements that have
been developed in our lines since
that time. They have markedly im-
proved the appearance and eating
quality of the watermelon flesh.
These characters, along with a tough
rind, and resistance to both an-
thracnose and Fusarium wilt are
combined in 'Dixielee,' and all but
the intense red flesh color are in
'Sugarlee.'
1964. In the early 1960's water-
melon mosaic built up quickly and
caused severe damage in some south
and central Florida watermelon
fields. In our search for resistance to
this disease, we obtained in 1964 all
the accessions of Citrullus species
that were then available from the
U.S. Regional Plant Introduction
Station at Experiment, GA. The
original 568 seed samples were sub-
divided according to seed differ-
ences into 848 total accessions.
These were planted in the field for
several seasons and, under condi-
tions of variable, but sometimes se-
vere, natural infection, three
accessions (P.I. 248178, P.I. 249010,
and P.I. 255137) were selected for
freedom from mosaic infection. A
backcrossing program was initiated
to incorporate this resistance into
'Charleston Gray', 'Jubilee', and
'Crimson Sweet', but the necessity
for relying on natural infection for
screening and the sporadic occur-
rence of mosaic in some seasons re-
sulted in the loss of the clearly
defined resistance demonstrated in
the original PI's. Some lines with
apparent tolerance to mosaic were
distributed to Hawaii, where they
reacted similarly to their perform-
ance here, but no variety releases
have been made. Work in this proj-
ect was discontinued in 1977, but
recently an African accession named
'Egun', reported to have resistance
to watermelon mosaic virus 2, has
been obtained, and crosses were
made in 1981 between some of our
better breeding lines and F2, F,, and
parent lines of this accession.
1969. Another major facet of our
breeding program was initiated in
1969, when crosses were made be-
tween several of our better large-
Vixielee (1919)
I
fruited lines and a number of small-
fruited cultivars, including 'New
Hampshire Midget', 'Sugar Baby',
and several from foreign countries
(Japan, Israel, Hungary). Early in
this program we aimed at the devel-
opment of smaller-fruited cultivars
of four fruit types: (1) a 'New
Hampshire Midget' type (about 5
lbs.); (2) a small (10 lb. average)
round gray type, with and without
stripes; (3) an intermediate size
(about 20 lb.) round gray type; and
(4) a 'Klondike' type (10-20 lb.).
We have since discontinued efforts
to select lines of the Klondike -
Peacock types because of inability
to eliminate uneven ripening char-
acteristics from these lines, and re-
cently we decided to discontinue
efforts with the 'New Hampshire
Midget' types because of a tendency
for fruit splitting in these lines. Our
present efforts toward the develop-
ment of small-fruited cultivars are
concentrated on several lines with
small, round, gray fruits (8-15 lb.
average) and several with interme-
diate size (about 20 lb.), round, gray,
striped fruits.
We are seeking to develop vari-
eties that might appeal to con-
sumers for their easier handling from
market to home and their more
convenient storage in the home re-
frigerator. We are also considering
their adaptation to shipping in car-
tons, a prime requisite for overseas
'Sugarlee (1981)
shipment. Our test plantings and
limited distributions of our small-
fruited selections to consumers in-
dicate a reluctant acceptance on the
part of growers and distributors but
an enthusiastic endorsement by many
consumers.
1972. Greenhouse and field tests
in 1971-72 and later confirmed the
suspicion that commercial seed stocks
of 'Jubilee' no longer had the same
degree of resistance to Fusarium wilt
as that found in original "breeder"
seed of 'Jubilee'. Increases of seed
from breeder stocks were made here
and distributed through the Florida
Foundation Seed Producers, Inc. to
seedsmen so they could produce
"registered" grade seed for sale to
growers. Registered grade seed is de-
fined by federal and state laws as
seed produced from foundation grade
seed. Growers willingly paid a pre-
mium price for such seed because of
its greater resistance to wilt, but
practical problems in the produc-
tion of sufficient quantities of regis-
tered seed have limited the success
of this approach to the problem.
Therefore, two other approaches
were initiated. A selfing program
was conducted for several years in
an attempt to eliminate any possible
loss of wilt resistance that might be
occurring because of heterozygosity
at one or more wilt-resistance -
governing loci, but since no appar-
ent progress was being made it was
terminated. A backcrossing pro-
gram to incorporate the high-level
wilt resistance of 'Smokylee' and
'Calhoun Gray' into 'Jubilee',
'Charleston Gray', and some other
varieties was also started in 1972.
This was a comprehensive program
that required continued selling,
backcrossing, and greenhouse test-
ing in a specific sequence, but it
seemed to be the most promising
method for getting improved wilt
resistance in 'Jubilee' and other
commercial cultivars. Test results
with backcross lines of 'Jubilee' and
'Charleston Gray' in 1978 were en-
couraging enough to warrant in-
creasing seed for replicated and
grower testing. Tests since 1978 have
shown that backcross lines are su-
ME= IN 11 NF1W
perior to the recurrent parent lines
not only in resistance to Fusarium
wilt but in many other characteris-
tics.
1973. Crosses were made begin-
ning in 1973 between some of our
more promising selections and sev-
eral Kentucky short internode
(dwarf) lines. This exchange of
breeding materials was facilitated on
a sabbatical visit here by H.C. Mohr.
Two dwarf mutants in watermelon
are governed by single, nonallelic,
recessive genes, and the F2 from the
cross between them segregates in a
9:3:3:1 ratio, with the double reces-
sive being expressed in a pro-
nounced bush-like plant.
Work on dwarf lines has been
somewhat limited, but recurrent
backcrosses with our better lines have
been made to both of the single
dwarf types and to the double dwarf.
1981. In addition to the re-
initiation of work on mosaic resist-
ance this year, we also initiated work
on gummy stem blight resistance.
An earlier attempt to utilize resist-
ance found in wild Citrullus acces-
sions was abandoned because of lack
of facilities and personnel to carry
out the procedures necessary for
imokylee ( 1911)
controlled inoculation experiments.
In 1981 we obtained Citrullus spe-
cies accessions P.I. 189225 and P.I.
271778, both of which have been
reported to have resistance to gummy
stem blight. Crosses between these
2 lines and some of our better lines
were made this season.
CURRENT PROGRAM
AND FUTURE
OUTLOOK
Our current program is concen-
trated in four major areas. It is in
these areas that we might anticipate
releases of new cultivars in the rea-
sonably near future: (1) small fruit
size types, (2) large round striped
fruit types; these include selections
for earlier maturity and higher yield
from lines similar to 'Dixielee' in
appearance and fruit quality, (3)
backcross 'Jubilee' types; similar in
appearance to 'Jubilee', but with a
higher level of resistance to Fusar-
ium wilt, improved fruit quality, and
higher yields, (4) backcross
'Charleston Gray' types; similar in
appearance to 'Charleston Gray', but
with a higher level of resistance to
Fusarium wilt, improved fruit qual-
ity, and higher yields.
Further in the future we might
look for cultivars of dwarf types, with
more compact vegetative growth and
the potential for higher yields of
melons per given area of land. We
might anticipate, also, develop-
ment of cultivars with resistance to
mosaic (at least that one caused by
watermelon mosaic virus 2) and re-
sistance to gummy stem blight. Re-
sistance to mosaic would remove
one of the major threats of severe
losses of yield and profits to individ-
ual growers in Florida from a disease
for which we presently have no
control. Resistance to gummy stem
blight would not only lessen the
losses suffered each year from this
.disease, but it would also greatly
lower production costs by reducing
the number of fungicidal sprays
needed, with concomitant environ-
mental benefits.
I
Grape Research
By Dr. J.A. Mortensen
Ever since early settlers came to
Florida and saw the abundant wild
grapevines in the woods, many at-
tempts have been made to grow Vi-
tis vinifera L. bunch grape cultivars
from Europe and, more recently,
from California. All plantings have
been short-lived due to strong dis-
ease pressure caused by fungi and
bacteria native to our humid, sub-
tropical climate.
Florida growers planted V. la-
brusca L. bunch grape cultivars in
the Orlando area in the 1890's,
which also failed because the vari-
eties grown were entirely unsuited
to Florida conditions.
A grape breeder in Texas, T.V.
Munson, crossed wild bunch grapes
from north and central Texas with
high-quality cultivars between 1880
and 1905. Through breeding, he in-
corporated native disease resistance
and Southern adaptability into usa-
ble cultivars of bunch grapes such as
'Extra', 'R. W. Munson', 'Carman',
'Armalaga', and 'Muench'. These
cultivars were brought into Florida
about 1920 and thousands of vines
were propagated and planted. By
1926 there were between 4,000 and
5,000 acres of Munson's bunch
grapes growing in central Florida,
and 500 or more acres in west Flor-
ida (Proc. Fla. State Hort. Soc.
29:71-73 and 215-220. 1926). Un-
fortunately, the bunch grape vine-
yards of Munson's varieties declined
in productivity due to several causes:
a disease known then as "vine de-
generation", the Mediterranean fruit
fly eradication program, depression
years prices after 1929, and post-
harvest shelling and drying prob-
lems with iced grapes shipped by rail
to Northern cities. A bunch grape
variety trial at the University of
Florida in Gainesville was planted
in 1924, and only 11 out of 63 va-
rieties still had living plants after 10
growing seasons.
The Florida Grape Growers As-
sociation (FGGA), organized in
1923, sent three men to Tallahassee
in 1933 to seek funds for grape re-
search. The first $3500 was appro-
priated in 1934 for use on grape
disease research at the Leesburg Field
Laboratory (now ARC, Leesburg).
During the 1930's the Leesburg
Laboratory conducted pest control
experiments which established proper
timing of spray applications to pre-
vent fruit rots and other fungus
diseases, but vineyards were
disappearing.
The cause of "vine degeneration"
was investigated in the 1930's and
1940's by controlled experiments on
soil fumigation, spraying, grafting
on resistant rootstocks, and minor
element fertilization, but none were
effective against the disease. How-
ever, newer organic fungicides tested
in the late 1940's and 1950's gave
excellent control of fruit rot and
other fungus diseases. Moreover, re-
search in the 1950's revealed that
the major cause of "vine degenera-
tion" was Pierce's disease (PD)
transmitted by leafhopper species
abundant in Florida. Recent work
at the Agricultural Research Cen-
ter, Leesburg, implicated a rickett-
sia-like bacterium as the causal agent
of PD. Cultivar resistance to PD
was found essential to contin-
ued productivity of grapevines in
Florida.
Munson's success in using native
Texas species as breeding parents
stimulated private viticulturists in
Florida to begin breeding with na-
tive Florida bunch grape species as
parents. In 1927, Dr. Charles Demko
(Altoona, Florida), began hybridiz-
ing American cultivars with Florida
native species such as V. simpsoni
Muns. He developed 3 self-fertile
cultivars: 'Dunstan', 'Taylor', and
'Florida Concord', but none have
survived as commercial cultivars. In
1936, Joseph Fennell (Princeton,
Florida) began breeding with V. ru-
fotomentosa S., V. gigas Fenn., V.
tiliafolia H. & B., V. shuttleworthi
House, and V. smalliana Bailey as
Florida wild bunch grape parents.
He developed nine cultivars of bunch
grapes, including 'Tamiami'. 'Tam-
iami' was grown commercially in
Florida to some extent during the
late 1950's, but eventually suc-
cumbed to PD. The other eight cul-
tivars either were lost or are of no
importance commercially.
Outstanding wild grapes were
collected in the early 1940's at ARC,
Leesburg, for possible use as sources
of longevity and resistance in breed-
ing. Initial F, seedlings were small-
fruited and of poor quality, but a
cross by L. H. Stover in 1945 gave
rise to 'Lake Emerald', released in
1954, which is resistant to PD and
good for wine and home gardens.
Subsequent breeding by Stover, us-
ing V. smalliana, V. simpsoni, and V.
shuttleworthi as sources of PD resist-
ance, led to the release of four other
PD-resistant bunch grapes: 'Blue
Lake' (1960), 'Norris' (1966),
'Stover' (1968), and 'Liberty' (1976).
'Blue Lake' is an excellent jelly and
dooryard variety, 'Stover' has po-
tential for fresh fruit and neutral
wine, and 'Liberty' has good fresh
fruit quality, principally a home gar-
den cultivar.
Numerous crosses and evalua-
tions are being continued at ARC,
Leesburg to develop long-lived cul-
tivars with competitive quality and
yield for both fresh market and
processing. Several outstanding se-
lections of bunch grape are now
being tested at Agricultural Re-
search Centers in Fort Pierce, Lees-
burg, and Monticello.
Muscadine breeding was begun
by the USDA at New Smyrna Beach
in 1907 with a cross in a Florida
grower's vineyard that later gave rise
to the first self-fertile muscadine
seedling. V. rotundifolia cv. 'Eden'
was crossed with a native Florida
male selection of V. munsoniana,
and the seedlings were grown at
Willard, North Carolina. Most self-
fertile muscadine cultivars in use to-
day trace back to this original cross
made in Florida.
Muscadine grapes have been
grown in back yards trained to over-
head arbors for many years in cen-
tral, north, and west Florida, proving
their adaptability here. However,
muscadines have become important
Blue Lake (1960)
II I
commercially in Florida only since
about 1968 with the availability of
proven PD-resistant varieties with
eating quality superior to the old
backyard cultivars. Muscadine vari-
ety trials began in 1959 at Leesburg,
and newer selections were tested
prior to naming under cooperative
agreements with breeders at N. C.
Agricultural Experiment Station in
Raleigh, Ga. Experimental Station
at Experiment, and U.S. Horticul-
tural Field Station at Meridian,
Mississippi. Outstanding cultivars
such as 'Fry', 'Summit', 'Triumph',
"Cowart', 'Southland', 'Jumbo',
'Chief', 'Tarheel', Dixie' (released
in 1976 jointly with N. C. State
Univ.), 'Welder' and 'Noble' have
been recommended as PD-resistant
commercial cultivars for Florida
growers based on tests at ARC's
in Ft. Pierce, Leesburg, Live Oak,
Jay, Monticello and in pivately
owned vineyards under cooperative
agreements.
The Florida muscadine acreage
increased from about 50 acres in
1970 to over 400 acres in 1981.
Most of the increase is in pick-your-
own vineyards ranging from 1 to 10
acres in size, since gross income per
ton of fruit is 4 to 6 times what it
would be selling bulk fruit wholesale
for other purposes. (Two growers in
Florida now have about 40 acres in
vines). There are over 60 musca-
dine grape growers in Florida with
one or more acres.
Another reason that few musca-
dine grapes have been successfully
channeled into bulk handling out-
Norris (1966)
Stover (1968)
"J *K
,,
Liberty (1976)
Dixie (1976)
lets is that only four varieties
('Southland', 'Carlos', 'Albemarle',
and 'Summit') can be harvested me-
chanically with a dry stem scar. A
breeding program with muscadines
was initiated at Leesburg in 1972 to
develop improved cultivars adapted
to mechanical harvest with rela-
tively uniform ripening. No new
muscadine cultivars have been re-
leased from the Florida breeding
program because it usually requires
10 to 12 years from the time of the
initial cross to the release of a su-
perior grape cultivar. However,
promising superior selections from
crosses made are being tested now
for possible release.
Marketing of bunch grapes has
been aided by cold storage studies
done in the 1930's at ARC, Lees-
burg. More work on cold storage,
fumigation, etc. on muscadine grapes
is urgently needed. Fresh market
studies in the 1970's through super-
market outlets have indicated the
feasibility of marketing 'Stover'
bunch grape as fresh fruit with good
consumer acceptance. Fresh mus-
cadines are now being sold through
retail outlets in Florida, marketing
in pint berry containers and in dis-
play trays in chain stores. The Flor-
ida Grape Marketing Association,
organized in 1979, has marketed fresh
muscadines cooperatively through
several outlets.
Processing of Florida-grown grapes
has been investigated since the
1960's at Gainesville and Leesburg,
indicating that certain cultivars of
bunch and muscadine grapes can
II
make acceptable canned juice, fro-
zen concentrate or wine. Fruit Wines
of Florida, Inc., Tampa, has also
tested cultivars for wine production.
Commercial wineries in Tampa,
Anthony, and Freeport now crush
and make wine in the state.
Bedding and mulching tests with
bunch grapes at Ft. Pierce revealed
the importance of bedding grapes
on flat, poorly drained land. The
appearance of grape root borer as a
Florida grape pest has triggered re-
search at Leesburg on controlling
this pest in addition to other insects
and diseases. The use of antibiotics
at critical periods of the year has
been investigated for the control of
PD on susceptible cultivars.
Rootstock trials of several bunch
grape clones with native species
parentage has revealed 'Dog Ridge'
(V. champini Planch) as superior to
other world-known stocks, being re-
sistant to PD, drought, and nema-
todes. 'Tampa' rootstock was recently
released from ARC, Leesburg, with
much less suckering tendency than
'Dog Ridge'. Other rootstock selec-
tions appear promising in tests cur-
rently under way at Leesburg.
Muscadine cultivars have not re-
quired rootstocks in Florida, but
grafting is becoming more popular
in order to change from old varieties
to newer ones.
Current grape research in Florida
includes grape breeding and genetic
studies, cultivar testing at 3 loca-
tions, pathological investigations of
PD and fungus diseases and their
control, entomological investiga-
tions on insect pests and control,
fertilization and irrigation studies,
growth regulator studies, rootstock
breeding and testing, taste panels
and test marketing studies for fresh
fruits and wines, and processing
studies with different cultivars of
bunch and muscadine grapes.
Future research on grapes should
include the above plus the follow-
ing: cold storage and fresh market-
ing studies with muscadine grapes,
herbicide and other weed control
methods, trellising, pruning and
training methods, investigation of
different processed products that can
be made from grapes besides wine,
nematode control methods, and the
use of cover crops, mulching, and
other cultural practices to maintain
soil fertility in vineyards.
Continued interest in grape pro-
duction in Florida is justified, sinct
"pick-your-own" vineyards are prof-
itable, and provide the public an
opportunity to harvest this world-
favorite fruit with their own hands.
Grapes for wine and other process-
ing outlets now seem feasible as the
bearing acreage increases across the
state. New disease-resistant vari-
eties form a basis for a viable indus-
try not heretofore possible in Florida.
ii
ARC, Leesburg, Faculty
Former Faculty
Dr. Marion N. Walker, Plant Pathologist and Head, 1929 1942
Dr. William B. Shippy, Plant Pathologist, 1929 1927
Mr. Kenneth W. Loucks, Plant Pathologist, 1929 1943
Mr. Carlos C. Goff, Entomologist, 1930 1939
Dr. John W. Wilson, Entomologist, 1930 1937
Dr. Edgar E. Hartwig, Agronomist, 1942 1943
Mr. Loren H. Stover, Horticulturist, 1941 1965
Mr. Clyde C. Helms, Agronomist, 1950 1955
Dr. G. Keith Parris, Plant Pathologist and Head, 1945 1951
Dr. Norman C. Schenck, Plant Pathologist, 1956 1969
Dr. Hugh A. Peacock, Agronomist, 1957 1958
Dr. Charles H. Curran, Entomologist, 1961 1971
Dr. Janson G. Buchert, Geneticist, 1959 1960
Dr. Carlos F. Balerdi, Horticulturist, 1966 1972
Current Faculty (in photograph below, from left to right)
Dr. James M. Crall, Plant Pathologist and Head, 1952
Dr. Warren C. Adlerz, Entomologist, 1958
Dr. John A. Mortensen, Geneticist, 1960
Dr. Gary W. Elmstrom, Horticulturist and Head, 1969
Dr. Donald L. Hopkins, Plant Pathologist, 1969
Funds for this special 50th Anniversary Leesburg ARC Research Report (WG-82-1) were provided by the SHARE (Special Help for
Agricultural Research and Education) private support program, which is part of the University of Florida Foundation, Inc. All programs
and related activities sponsored or assisted by the Florida Agricultural Experiment Stations are open to all persons regardless of race, color,
national origin, age, sex or handicap.
HISTORIC NOTE
The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
of Florida
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