|
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
Fl' L
GZJ BUNCH GRAPE FIELD DAY
U UNIVERSITY OF FLORIDA, IFAS
AGRICULTURAL RESEARCH & EDUCATION CENTER, LEESBURG
Tuesday, July 10, 1984
9:00 a.m. to Noon
Dr. Timothy Crocker, IFAS Fruit Crops Department Moderator
9:00 9:40 a.m. Registration and bunch grape cultivar
fresh fruit taste panel (all people in attendance are
invited to rate varieties and breeding selections for
quality).
9:40 a.m. Welcome by Dr. Gary Elmstrom, Center Director,
AREC, Leesburg.
9:45 10:50 a.m. Discussion of grape research in progress
and introduction of visiting grape and wine experts.
Dr. D. L. Hopkins, Plant Pathologist, AREC Leesburg
Dr. W. C. Adlerz, Entomologist, AREC Leesburg
Dr. R. P. Bates, Food Scientist, Gainesville
Remarks from visiting scientists as introduced:
Dr. Vincent Petrucci, Cal. State U., Fresno, CA
Dr. Justin Morris, U. of Ark., Fayetteville, AR
Dr. Bruce Zoecklein, U. of Mo., Columbia, MO
Dr. Leonard Mattick, N.Y. Agr. Expt. Sta., Geneva, NY
Dr. J. A. Mortensen, Geneticist, AREC Leesburg
10:55 Noon A guided tour of the experimental grape vine-
yards will be conducted. Included in the tour will be
a mist propagation unit, two screenhouses, an overhead
arbor, new varieties and breeding selections, fungicide
trials, growth-regulator trials, a new 3-acre seedling
block under suspended maxijet irrigation, and a new
vineyard sprayer in operation. (Refreshments on tour
courtesy of Maxijet Irrigation and Foremost Fertilizer
Company).
Because of yield records we ask that bags and containers not
be brought on the vineyard tour.
H4UME LIBRARY
Leesburg AREC Research Report (LBG 84-2) 2 '
500 Copies
!.F.A.S.- Univ. of Floride
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research,
educational information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.
-2-
Grape Fungicide Tests. (D. L. Hopkins)
In 1983 fungicides were evaluated for their effectiveness
on grape diseases in the AREC, Leesburg vineyard. The
fungicide trial was conducted on 'Stover' grapevines. Test
plots were arranged in randomized blocks with three vines
per plot and three replications.
Treatments and rates per acre were as follows: (A) Benlate
at 1.0 pound plus Orthocide 50W at 2.0 pounds; (B) Benlate
at 1.5 pounds; (C) Orthocide 50W at 3.0 pounds plus Manzate
D at 1.5 pounds; (D) Baycor 50W at 1.0 pound plus Agridex
at 1.0 pint; (E) DPX H6573 40% at 1/4 ounce ai.; (F) DPX
965-4L at 12 ounces ai.; and (G) DPX 965-4L at 24 ounces ai.
Treatments were begun on April 21 and applied biweekly
through July 5. Approximately 150 gallons of spray per
acre was applied to the plots. Anthracnose ratings were
made in May, June, and July, and the percentage fruit rot
was determined at harvest July 25.
Anthracnose was already established in the plots prior to the
first fungicide application and this is reflected in the high
disease ratings on May 12 (Table 1). All fungicide treatments
provided significant control of anthracnose. Baycor + Agridex
and DPX H6573, two fungicides that are still experimental on
grapevines, were most effective. The recommended treatments,
Benlate + Orthocide and Orthocide + Manzate D also were very
effective. DPX 965 appeared to be at least as effective as
Benlate against anthracnose.
Fruit rot was a combination of anthracnose and bitter rot
(Table 1). The ranking of treatments for the control of
fruit rot was similar to that for anthracnose. The low yield
in the unsprayed plots was primarily due to fruit rot.
While current fungicide treatments, such as Benlate + Orthocide
or Manzate D + Orthocide, provide adequate control of grapevine
diseases in Florida, some of the newer materials have the
potential for even better disease control.
-3-
Table 1. Control of grape diseases with fungicides, 1983.
1
Treatment Anthracnose rating % fruit Yield
5/12 6/14 7/18 rot2 (Ibs/plot)
Baycor + Agridex 2.6a3 1.2a 1.0a 2a 27.5a
DPX H6573 2.6a 1.6a 1.4ab 5a 25.7a
Benlate + Orthocide 2.9a 1.4a 2.3 bc 8ab 28.4a
Orthocide + Manzate D 2.1a 1.4a 2.4 bc 13ab 17.7ab
DPX 965 (12 oz.) 3.6a 2.0a 2.6 cd 20 b 23.0ab
DPX 965 (24 oz.) 2.8a 1.5a 2.6 cd 33 c 28.3a
Benlate 4.4ab 2.8a 3.5 d 53 d 16.4ab
Untreated 5.4 b 5.9 b 6.0 e 94 e 7.0 b
Anthracnose was rated on a scale of 0-10.
2
Fruit rot was due to anthracnose and bitter rot.
Mean separation in columns by Duncan's new multiple range
test, 5% level.
In 1984, we have a test underway that is very similar to the
1983 test. This test will be observed on the Field Tour.
Treatments and preliminary results are given in Table 2.
Table 2. Control of grape anthracnose, 1984.
Anthracnose rating2
Treatment1 4/30 7/5
(A) DPX H6573 (1/4 oz.)(3 wk) 1.0a 1.2a
(B) DPX H6573 (1/8 oz.)(3 wk) 1.0a 1.5 b
(C) Benlate + Orthocide (1 lb. + 2 lb.) 1.0a l.la
(D) Baycor + Agridex (1 lb. + 1 pt.) l.la 1.3ab
(G) Manzate D + Orthocide (2 lb. + 2 lb.) 1.5ab 1.8 c
(E) XE 779L (0.1 lb.) 2.1abc 3.1 d
(F) Bayleton (0.25 lb.)(3 wk) 2.5 be 3.5 e
(H) Unsprayed 3.1 c 4.1 f
Rate per acre is given. Sprays were applied every 2 weeks
except for A, B, and F.
2
Anthracnose was rated on a scale of 0-10. Mean separation
in columns by Duncan's new multiple range test, 5% level.
Disease Control in Florida Grapes. (D. L. Hopkins)
Disease control is an absolute necessity to successful bunch
grape production in Florida. The most severe fungal disease
is anthracnose, which affects both foliage and fruit. There
are 3 other fungal fruit rots black rot, ripe rot, and
bitter rot that must be controlled. A number of leafspot
diseases become serious problems during late summer. These
diseases must be controlled to prevent premature defoliation
in the fall, thus assuring a stronger vine in dormancy and
better yields in the following year.
A long growing season, high temperatures, abundant rainfall,
and high humidity make bunch grape disease very difficult to
control in Florida. Therefore, a vigorous spray program must
be started in the spring when buds are 2-6 inches long and
continued throughout the season. Fungicides should be
applied every 10-14 days until a week before harvest, and
every 3-4 weeks from harvest through November or until
dormancy.
Since muscadines are resistant to anthracnose, the first
spray can be delayed until just prior to bloom. As with
bunch grapes, fungicides should be applied every 2 weeks
through harvest. One or 2 postharvest applications are
beneficial. The fungicides recommended for grape disease
control in Florida are listed in the following table. A
spreader-sticker may be included in the spray.
Amt./100 gal. Amt. per Days before
Fungicide per acre gal. harvest
Manzate D 1 1/2 lb. 1 1/2 TBS2 7
Dithane M-22 Special 1 1/2 lb. 1 1/2 TBS 7
Captan 2-4 lb. 2-4 TBS 7
Phaltan 2-4 lb. 2-4 TBS 7
Benlate 1-1 1/2 lb. 1-1 1/2 TBS 7
1This is the recommended minimum number of days between last
application of fungicide and harvest.
TBS = tablespoon.
Since the activity of these fungicides against specific
diseases varies, it is advisable to use combinations of
materials in a grapevine disease control program. For
example, Benlate may be tank mixed with either Orthocide
-5-
(captan) or Manzate D or Dithane M-22 Special. Orthocide
and Manzate D or Dithane M-22 Special is also an effective
tank mix.
Pierce's Disease of Grapevine. (D. L. Hopkins)
Pierce's disease (PD) is caused by a small, xylem-limited
bacteria. The symptoms include decline of vigor, marginal
necrosis of leaves, and often death of the plant. This
disease limits grape production in Florida. Both European
type (Vitis vinifera) and American type (V. labrusca) bunch
grapes succumb to PD.
Presently, the only effective control for PD is resistance.
To be productive in Florida, grapes must be resistant to
PD. Most varieties of muscadine grape have a high level of
resistance, but some are susceptible. 'Pride', 'Carlos',
'Lucida', and 'Scuppernong' are examples of muscadine
varieties that are susceptible to PD in Florida. Among
bunch grapes, only varieties developed at the AREC, Leesburg
have enough resistance to PD to be productive in Florida.
These include 'Stover', 'Lake Emerald', 'Blue Lake',
'Suwannee', 'Daytona', and 'Conquistador'.
Insect Control on Florida Bunch Grapes. (W. C. Adlerz)
Many insects can be found on bunch grapes in Florida. Some
can be severely damaging and control may be necessary. To
keep spraying to a minimum, growers may wish to become
acquainted with insects having the greatest damage potential,
inspect vines frequently, and spray only when necessary.
This is a good strategy, since preventive spraying will not
be necessary in most cases. Exceptions occur when growers
experience annual problems with grape seed chalcid, or if the
grower adopts spraying to control newly emerged root borer
larvae in the fall as part of the grape root borer control
program.
Among the most persistent and damaging insects are the grape
flea beetle, grape leafhopper, and grape root borer.
These are discussed briefly.
Grape Flea Beetle
Grapevines are damaged by adult and by larval grape flea
beetles. Adult beetles are dark bluish-black and about
3/16 inch long. They are usually the first insects of the
growing season to damage grapevines. Adult beetles feed on
primary buds which then cannot develop into primary canes,
so crop yield is reduced.
-6-
G')ape f'lCa be'tlles brood In the vineyard, and females lay
eggs on various parts of the vine. Larvae are brown,
spotted with black, and about 1/4 inch long. They feed on
the upper surface of leaves and on developing flowers and
buds, reducing yields.
Since both adults and larvae are easily seen, vineyards should
be carefully monl tored in the early season, paying special
attention first to cane and then to flower buds. Insecticides
should be applied when necessary.
Grape Leafhopper
Grape leal'hoppers can be expected to infest vines each year.
Adult and immature insects feed on the undersides of leaves
causing pale feeding spots visible from above and even general
discoloration. Vine growth and sugar content of the grapes
may be reduced and seriously affected vines will be weakened.
Excreta from these insects may collect on the fruit which
will then be spotted and possibly covered with sooty mold.
Grape leafhopper adults are light colored, about 1/8 inch
long and very active. Immatures are very small, often difficult
to see, usually immobile, but can be provoked to activity by
touching.
An application of insecticides made prior to flowering and a
second 2-4 weeks after flowering will result in good leafhopper
control If one elects preventive spraying.
Grape Root Borer
Grape root borer may be the most serious threat to grapes in
Florida, having the potential to kill both bunch and muscadine
vines. Larvae tunnel in the roots, reducing root diameters
and girdling even large roots. Large larvae often make their
way into the crown of the plant. Marked reductions in vine
vigor and yield is cause to suspect root borer activity.
Detection is by exposing part of the root system to inspect
for larvae or damaged roots.
Larvae remain in the noil for about 22 months before coming
to the surface to pupate. In Florida, the adult moths are
active and can be seen in the vineyard in daytime, mainly in
October. Adults are brown, wasplike moths with yellow markings.
Females lay e:-.; on a variety of plant materials or on the
ground. Newly hatched larvae tunnel through the soil to the
roots.
The only available chemical control method is spraying the
ground to kill newly hatched larvae in late September and
October. The chemical barrier keeps the larvae from penetrat-
IIng to the grapevine roots. Larval control with this method
has been found effective in Florida. Use Lorsban according
to label directions. Do not apply less than the 2 quarts
of dilute spray per vine called for on the label. A
concentration of 2 pints of Lorsban 4E/100 gallons of
finished spray is effective. Since the label limits
application to one per season it would be best to make the
application the second or third week in October.
Root borers have been found in most varieties of grapevines
in Florida, (Table 2).
Other Insects or Damage Commonly Seen
Grape leaf folders, grape leaf skeletonizers, grape leaf
miners, grape phylloxera, grapevine aphids, and anomala
beetles are commonly seen in the vineyards.
All are- considered minor pests that may not require control
efforts. Grape leaf folders and skeletonizers may be
especially abundant in the late summer and fall. Skeletonizers
(brightly colored yellow and black striped larvae feeding
in groups) should not be allowed to denude vines, so they
should be sprayed if necessary. If foliage disappears,
remaining foliage is smeared with black frass, and no insects
are seen, look for anomala beetles under vines, or look for
insects eating foliage at night.
i ti I '*'4kk'
-8-
Table 2. Occurrence of grape root borers on various grapes in the
laboratory research planting and a commercial vineyard:
cast pupal skins at the soil surface.
Pupal skins per vine
Laboratory1 Commercial2
1979 1980 1981 1980 1981
Liberty (Lake Emerald) 0.2 0.5
Stover (Lake Emerald) 0.4 1.0
Blue Lake 0.4 1.7
Lake Emerald 0.8 0.4
Norris (Lake Emerald) 1.2 1.0
L4-33 (Dogridge) 2.3
Southland 0.0 0.5 0.4 0.6 0.4
Magnolia 0.0 0.2 0.0 0.6 0.5
Thomas 0.2 0.3 0.6
Redgate 0.2 0.8 1.0
Chief 0.2 0.0 0.5 0.3
Regale 0.3 0.0 0.0
Magoon 0.5 0.2 0.3
Tarheel 0.7 0.3 0.6 1.4 0.4
Welder 0.8 0.0 0.6 2.6 0.6
Watergate 0.8 0.0 0.0
Fry 0.8 0.3 0.5 2.6 1.2
Creek 0.8 0.0 0.3
Dixie 1.2 0.3 0.8 0.4 2.2
Dearing 1.2 0.3 0.0
Jumbo 1.3 0.0 1.3 4.0 3.6
US42-12B 2.2 0.2 0.5
Cowart 2.2 0.0 0.6
Noble 2.3 0.3 0.8
Hunt 2.3 0.6 1.4 3.4 1.2
Sugargate 3.3 0.3 2.6
Carlos 3.6 0.2 0.0 2.5 1.7
IIggin 4.0 0.0 0.7 2.7 2.3
Average from 6 single-plant replications.
2Average from 5 to 15 plants of each variety.
Average from 5 to 15 plants of each variety.
Insecticides for Bunch Grapes
When to spray
Insecticide
Bud break to flowering
(or later for beetle)
Pre-bloom and
2-4 weeks after bloom
Late April through
May, weekly
Post harvest
As needed
For mid September to
early November control
of new larvae
Malathion
Carbaryl
Malathion or
Methoxychlor or
Flea beetle
Leafhopper
Cyabaryl (Sevin)
Methoxychlor or Leafhopper
Carbaryl (Sevin)
Malathion Seed
Chalcid
(as above) Leafhopper
Malathion Aphids
Methoxychlor Leafhoppers 2
or Caterpillars
Carbaryl (Sevin) Fruit beetles
Lorsban
Root borer
1.5 pints 57% emulsifiable concentrate/100 gal.
water
1.5 teaspoons/gallon
Days before harvest 3
2 pounds 50% carbaryl wettable powder/100 gal.
water
2 tablespoons/gallon
Days before harvest 0
Methoxychlor 2 pounds 50% methoxychlor wettable powder/100
gal. water
2 tablespoons/gallon
Days before harvest 14
Lorsban
Specific recommendation on label
1When this insect is a problem preventive spraying will be
needed.
2Grape leaf folder, leaf skeletonizer, hornworms, berry moths.
In central Florida the earliest observed flight of root borer
moths has been September 9 and the latest has been November 3.
Peak flight was the first week in October in 3 of 5
observations. Apply Lorsban the second to third week in
October to kill new larvae. Two pints of Lorsban 4E/100
gallons have been found effective against newly hatched larvae
in Florida.
Pest
-5-
(captan) or Manzate D or Dithane M-22 Special. Orthocide
and Manzate D or Dithane M-22 Special is also an effective
tank mix.
Pierce's Disease of Grapevine. (D. L. Hopkins)
Pierce's disease (PD) is caused by a small, xylem-limited
bacteria. The symptoms include decline of vigor, marginal
necrosis of leaves, and often death of the plant. This
disease limits grape production in Florida. Both European
type (Vitis vinifera) and American type (V. labrusca) bunch
grapes succumb to PD.
Presently, the only effective control for PD is resistance.
To be productive in Florida, grapes must be resistant to
PD. Most varieties of muscadine grape have a high level of
resistance, but some are susceptible. 'Pride', 'Carlos',
'Lucida', and 'Scuppernong' are examples of muscadine
varieties that are susceptible to PD in Florida. Among
bunch grapes, only varieties developed at the AREC, Leesburg
have enough resistance to PD to be productive in Florida.
These include 'Stover', 'Lake Emerald', 'Blue Lake',
'Suwannee', 'Daytona', and 'Conquistador'.
Insect Control on Florida Bunch Grapes. (W. C. Adlerz)
Many insects can be found on bunch grapes in Florida. Some
can be severely damaging and control may be necessary. To
keep spraying to a minimum, growers may wish to become
acquainted with insects having the greatest damage potential,
inspect vines frequently, and spray only when necessary.
This is a good strategy, since preventive spraying will not
be necessary in most cases. Exceptions occur when growers
experience annual problems with grape seed chalcid, or if the
grower adopts spraying to control newly emerged root borer
larvae in the fall as part of the grape root borer control
program.
Among the most persistent and damaging insects are the grape
flea beetle, grape leafhopper, and grape root borer.
These are discussed briefly.
Grape Flea Beetle
Grapevines are damaged by adult and by larval grape flea
beetles. Adult beetles are dark bluish-black and about
3/16 inch long. They are usually the first insects of the
growing season to damage grapevines. Adult beetles feed on
primary buds which then cannot develop into primary canes,
so crop yield is reduced.
-10-
Weed Control in Florida Vineyards. (J. A. Mortensen)
One of the secrets of successful grape growing is an
integrated program of weed control involving mechanical
tools, herbicides and mulches. Weed control between vine
rows is much easier to accomplish than that under the
trellis itself. Herbicides are rarely used for weed control
between rows since mowing, disking, or rototilling are more
practical and less expensive both in young vineyards and
mature vineyards. The discussion below concerns control
of weeds in the vine row where disking and mowing are not
possible.
Young Vineyards
Mulching with 3 inches of oak leaves or pine needles around
each newly set grapevine helps control weeds and conserve
soil moisture. Hoeing of weeds in small vineyards is usually
replaced by herbicide spraying in vineyards one acre or larger.
Paraquat kills all the leaf surface it covers, including
grapevine foliage. A tractor-mounted boom with a nozzle
surrounded by a cone-shaped shield to prevent drift of spray
in windy weather is effective in directing the material to
a band along each side of the row without getting on the
grape plants. Sufficient overlap of spray bands between
vines in the row is essential to avoid leaving a green
strip of weeds under the trellis wires. Herbicides may
need to be applied early in the morning or late in the
afternoon to avoid mid-day windiness. Also, spray when
forecast for showers is less than 50%. Roundup (Glyphosate)
weed killer gives excellent control and can be sprayed on
actively growing weed leaves, but severe injury to vines
can result if any gets on grape leaves. In Stoneville, MS,
a wipe-on attachment was developed for use with Roundup,
with a wick for keeping the material available. This is
safer for vines than spraying. Surflan can be applied
on young vineyards as a pre-emergence weed control.
Mature Vineyards
(3 years or older)
Karmex (Diuron) herbicide is an effective pre-emergence herbi-
cide if applied once a year, usually in March. Weed growth
occurring in the rows in mid- to late summer can be burned down
with Paraquat herbicide, hoed, or sprayed with Roundup. Karmex
and Paraquat may be mixed in the spray tank where both a pre-
emergence and "burn-down" of existing weeds are needed at
once. Thorough cleaning of spray tank, hose, and nozzles
by draining, flushing, and cleaning with detergent are
recommended following the use of herbicides. Roundup can
-11-
eliminate weed growth for two or three months, whereas weed
regrowth occurs within three weeks with Paraquat. A tank
mix of Surflan and Roundup has proved effective at A.R.E.C.,
Monticello for pre-emergence and "burn-down" control.
Herbicides Used for Grapes
Product
Paraquat
Karmex 80W
Surflan 75W
(oryzalin)
Roundup2
(glyphosate)
Rates Used
1 qt./50 gal.
4 tsp./gal.
3 Ibs./sprayed
acre
2 tsp./gal./
100 sq. ft.
Amt. of X-77
Spreader
4 oz./50 gal.
1/2 tsp./gal.
None required
4 Ibs./sprayed None required
acre
4 Ibs./sprayed None required
acre
4 Tbs. + 2 tsp.
per gallon
Specifications
Wet above-ground
portion of weeds
whenever needed
(3 to 5 times a
year).
Wet surface of
ground evenly in
a band on each
side of row (once
each year, usually
March). Vines
must be 3 years old
and 1 1/2 inches
trunk diameter.
Safely sprayed
right after
planting. Irrigate
after application
if 1/2" rainfall
does not occur.
Wet weed leaves
but carefully avoid
spraying grapevines or
suckers from vines.
Some vine damage may occur on coarse sands
after application.
if heavy rains occur
2Roundup phytotoxic effects to grape leaves can easily occur in
drifted vapor within 25 ft. of the spray nozzle. Use of low
pressure and an herbicide type nozzle is essential.
-12-
irrigation of grapes. (J. A. Mortensen)
Research on irrigation of grapes in Florida is very limited.
A one-acre block of muscadine grapes was planted in 1974, and
in 1976 was divided into 6 blocks -- 3 microjet-irrigated
and 3 non-irrigated. Results in 1977 showed a 68% increase
in yield and an 83% increase in weight of prunings (Table 6).
1977 was a relatively dry year which accentuated irrigation
effects. In 1978 only 19% increase in yield was obtained,
but an 86% increase in pruning wood. 1978 had more rainfall,
so the advantage of irrigation was less marked. In 1979
there was a 12% reduction in yield in the irrigated compared
with non-irrigated blocks, the pruning weights were 34% higher
in the irrigated plots.
Varietal differences in response to irrigation were evident
(Table 7). 'Welder', 'Fry', and 'Tarheel' were the most
responsive to irrigation in all 3 years, whereas 'Jumbo' and
'Southland' were relatively unresponsive.
Pruning wood weights also showed varietal differences (Table 8),
with 'Higgins', 'Regale', 'Tarheel', and 'Doreen' showing
the most increase from irrigation and 'Carlos', 'Jumbo',
and 'Dixie' showing a decrease.
Microjet irrigation appears to be superior to drip irrigation
in that either dry or liquid fertilizers may be used, whereas
with drip systems only liquid fertilizers can be used. It
is recommended that the conducting tubes along each row be
elevated by stakes or other support systems to a height of
12 to 25 inches to reduce line breaks and interference of
water distribution.
-13-
Table 6. Effects of microjet irrigation in a one-acre block of
muscadine grapes planted in 1974.
Fruit yields (lb/vine) Pruning wts (Ib/vine)
Incr. Inc
Year Irrig. Non-Irr. (%) Irrig. Non-Irr. (%
1977 17.3 10.3 6- 7.7 4.2
1978 35.1 29.5 19 8.0 4.3 8
1979 40.0 45.4 -12 7.5 5.6 3
Mean 30.8 288 -8 7.7 T477
r.
)
3
6
4
Table 7. Yield increase due to microjet irrigation of 12 muscadine
cultivars planted in 1974.
Pounds per vine 3-yr
Cultivar 1977 1978 1979 Total Tons/Acre
Welder 9.1 11.9 17.I 38.8 4.5
Fry 12.3 12.9 10.0 35.2 4.1
Tarheel 6.8 13.7 6.3 26.8 3.1
Higgins 20.4 12.3 -10.4 22.3 2.6
Carlos 5.0 7.4 8.9 21.3 2.5
Noble 18.0 7.0 5.9 19.1 2.2
Cowart 7.2 8.9 2.4 18.5 2.2
Dixie 8.1 7.1 1.8 13.4 1.6
Regale 14.9 2.6 6.2 11.3 1.3
Doreen 10.0 4.7 9.1 5.6 0.7
Jumbo 6.2 1.0 6.7 0.5 0.1
Southland 0.8 0.9 2.1 3.8 -0.4
Table 8. Pruning wood weights from 12 muscadine cultivars with and
without microjet irrigation.
Pounds per vine
1977 1978 1979 Mean
Cultivar Irr. N.I. Irr. N.I. Irr. N.I. Irr. N.I.
Higgins 13.2 7.3 10.6 6.1 7.1 10.8 10.3 8.1
Regale 12.4 4.5 8.4 7.9 7.2 9.4 9.3 7.3
Tarheel 8.1 4.4 6.0 3.9 7.2 7.9 7.1 5.4
Doreen 6.7 4.5 8.6 6.3 9.6 9.6 8.3 6.8
Noble 8.9 4.5 8.4 6.0 6.7 9.9 8.0 6.8
Welder 5.4 4.0 6.5 5.4 7.2 6.7 6.4 5.4
Cowart 4.6 3.2 4.9 4.2 6.9 6.5 5.5 4.6
Southland 2.8 1.9 3.1 2.5 5.5 5.4 3.8 3.3
Fry 7.0 2.2 6.4 7.9 4.6 6.7 6.0 5.6
Carlos 16.8 9.5 11.2 12.7 4.8 13.8 10.9 12.0
Jumbo 10.1 5.6 8.3 9.8 7.4 14.0 8.6 9.8
Dixie 10.4 6.5 7.4 8.3 7.8 15.6 8.5 10.1
-14-
Fertilizer N-P-K Factorial Experiment. (J. A. Mortensen)
A ratio of 3:1:2 or 3:1:) was apparently superior to the
1:1:1 ratio of N:P:K for grapes. However, differences were
not statistically significant for yields or weight of dormant
pruning wood. Under conditions of no irrigation, the growth
and yield of Blue Lake and Norris bunch grapes were greater
where clay was 2.5 to 5 ft. below surface than where it was
5 or more feet deep.
Breeding grapes for Florida. (J. A. Mortensen)
An active breeding program with grapes has been continued
since 1945, when Loren Stover made the first significant
cross. The emphasis was on bunch grapes until 1972, when
muscadine breeding was also included in the program. New
varieties coming from the program are as follows: Lake
Emerald (1954), Blue Lake (1960), Norris (1966), Stover
(1968), Liberty (1976), Dixie (1976, jointly with N.C.
State Univ.), Tampa rootstock (1982), Daytona (1983),
Suwannee (1983), and Conquistador (1983). A number of both
bunch and muscadine selections appear promising, and best
ones should be released in the near future. No seedless
selections are ready yet, but more emphasis on seedless
grape breeding has begun. Fla. BD8-77 bunch grape may have
potential as a seedless cutlivar. Efforts to transfer
seedless genes from bunch grapes to muscadines by way of
bunch-muscadine hybrids are being made. P9-15, a fertile
bunch-muscadine hybrid being used as an intermediate carrier
of seedless genes, can be seen on the tour.
Growth regulators and girdling. (J. A. Mortensen)
Increases in berry size and level of seedlessness were
obtained using gibberellic acid (75 ppm) at two weeks after
capfall. Girdling gave slight increase in berry size
(removing a 3/16-inch ring of bark from trunk 2 weeks after
capfall). Effects of thiourea and gibberellin on budbreak
of Daytona, and effects of Alar on fruit set of 4 cultivars
can be seen on the tour.
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