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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
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Copyright 2005, Board of Trustees, University
GRAPE FIELD DAY
A 'ugust 23, 1991
Research and Education Center-Leesburg
IFAS, University of Florida
Leesburg CFREC Research Report LBG 91-4
! ;-' ra
GRAPE FIELD DAY
Central Florida Research and Education Center, Leesburg
IFAS, University of Florida
August 23, 1991
Dr. Tim Crocker, Extension Horticulturist, Fruit Crops
9:30 Registration and participation in fresh fruit taste panel of grape
cultivars and selections
10:00 Welcome, Dr. Charles A. Conover, Center Director
10:05 Dr. Tim Crocker, Extension Horticulturist Gainesville
10:15 Dr. Dennis J. Gray, Developmental Biologist Leesburg
10:25 Dr. Susan E. Webb, Entomologist Leesburg
10:35 Dr. Donald L. Hopkins, Plant Pathologist Leesburg
10:45 Dr. Robert P. Bates, Food Scientist Gainesville
10:55 Dr. Charles A. Sims, Enologist Gainesville
11:05 Grand tour of vineyards to observe research and cultivars
Noon End of Field Day
Research updates will be given on all grape, wine, and juice
research in progress with both bunch grapes and muscadine grapes. This
year the GRAPE FIELD DAY was scheduled at the time the muscadine
grapes are ripe. Next year it is planned at the time the bunch grapes are
ripe. We will attempt to answer any questions as time permits, so feel free
to speak up.
Outstanding wild grapes were collected in the early 1940s, and
brought to AREC-Leesburg, for use as sources of breeding material for
longevity and resistance. Initial Fl 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, using V smalliana, and V.
simpsoni, and V shuttleworthii as sources of 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 potential
for fresh fruit and neutral wine and 'Liberty' has good fresh fruit quality,
principally, a home garden cultivar.
Three new, PD-resistant, bunch grape cultivars were released in
1983: 'Conquistador', 'Suwannee', and 'Daytona'. 'Conquistador' is similar
in appearance and flavor to 'Concord', yields well when grafted on 'Dog
Ridge' or 'Tampa' rootstock, and produces high quality fresh fruit.
'Suwannee' has light-green berries suitable for wine. 'Daytona' has pink
berries and is recommended for fresh fruit consumption primarily as a
dooryard cultivar. In 1986, Florida's first seedless grape cultivar, 'Orlando
Seedless', was released. 'Orlando' is recommended as a fresh fruit cultivar
and best production occurs when grafted on 'Tampa' rootstock. 'Blanc Du
Bois', a premium white wine grape, was released in 1987. See Table 1 for
a list of the bunch grape cultivars developed at Central Florida Research
and Education Center at Leesburg.
Table 1. Pierce's-disease-resistant, grape cultivars developed at CFREC
Cultivar Release Date Fruit Color Use
Lake Emerald 1954 Green Wine
Blue Lake 1960 Purple Jelly
Norris 1966 Purple Fresh
Stover 1968 Green Fresh, Wine
Liberty 1976 Red Fresh
Conquistador 1983 Purple Fresh, Wine
Suwannee 1983 Green Fresh, Wine
Daytona 1983 Pink Fresh
Orlando Seedless 1986 Green Fresh
Blanc Du Bois 1987 Green Wine
Dixie 1976 Bronze Fresh
Alachua 1990 Black Fresh, Jelly
One reason that few muscadine grapes have been successfully
channeled into bulk handling outlets is that only four varieties ('Southland',
'Carlos', 'Albermarle', and 'Summit') can be harvested mechanically with a
dry stem scar. A breeding program with muscadines was initiated at
Leesburg in 1972, to develop improved cultivars adapted to mechanical
harvesting with relatively uniform ripening. This resulted n the release of
'Dixie' (1976), a bronze cultivar, and 'Alachua' (1990), a uniform ripening
black cultivar. Additional superior selections from crosses are being tested
now for possible release.
Two Elite Muscadines for Possible Release as Cultivars:
1. Fla AA7-44 Originated from a cross of 'Triumph' x 'Welder' in
1983. It first fruited in 1987. It has yielded consistently since that
time with a medium vine vigor. Clusters average 73.6 grams and 9
berries per cluster. Berries are round, bronze, and average 8.9
grams each. ('Fry' average 10.4) Average date of ripening at
Leesburg is August 18. Seeds per berry average 3.4.
Pulp has a firmness unlike most muscadine cultivars and the skin is
crunchy, making it edible. The picking scar is moderate having a
average of 53.3% dry scar which is better than 'Fry' with 33.3% dry
Fla. AA7-44 appears to have resistance to all major diseases of
grape. However, for ultimate productivity and disease control it
should be sprayed with fungicide for preventative measures.
Fla. AA7-44 will be mainly recommended for fresh fruit
consumption. It has not been tested for wine or other processing
The principal advantages of Fla. AA7-44 are disease resistance, very
high rating for fresh fruit quality, self fertility, high soluble solids
and good productivity. It propagates readily from herbaceous
cuttings in June and July. It may be planted in commercial or
dooryard plantings without the need of another cultivar as pollinizer.
2. Fla. AA12-3 Originated from a cross of 'Summit' (Muscadine) x
P9-15 interspecificc hybrid; part bunch and part muscadine) in 1979.
It first fruited in 1984. Its fruit yields are medium with an excellent
vine vigor. It is unique in appearance because of its leaf shape with
deep sinuses, resembling somewhat, that of a maple leaf. It could
be used for ornamental purposes. Flowers are self fertile. Clusters
average 76.7 grams and 12.8 berries per cluster. Berries are oval,
black and average 6.3 grams each. Seeds per berry average 3.6.
Average date of ripening at Leesburg is August 22. Fruit has good
texture with a unique delightful flavor. Ripens uniformly and fruit
can hang on the vine for a longer period of time than most
muscadine cultivars. Picks with a dry scar of 90%.
Fla. AA12-3 is highly resistant to disease making it much easier to
care for than most other cultivars. It is possible that it may be
grown without the need of a regular preventive spray program with
Fla. AA12-3 will be recommended for a dooryard and u-pick grape.
It is unknown at this time as to its use for wine because none has
been made from it. However, in tests run here at Leesburg, Fla.
AA12-3 has not done well in color stability. Juices have turned
brown rapidly indicating that it will not do well as a wine cultivar.
The principal advantages of Fla. AA12-3 are extreme disease
resistance, very good fresh fruit quality, uniform ripening and
ability to hang on vine for longer periods of time, excellent
picking scars, and can be used for ornamental purposes. Fla.
AA12-3 propagates readily from herbaceous cuttings in June
and July. It is self-fertile and therefore, may be planted
alone without another cultivar as pollinizer. Fla. AA12-3 is
also very vigorous, so does not require grafting.
BIOTECHNOLOGY OF MUSCADINE GRAPE
Dennis J. Gray
Seedless Muscadine Grape Breeding
Although muscadine grape is a native, adapted fruit crop of the
southern United States and is prized for relative ease of care and superior
fruit flavor, the muscadine grape industry has not achieved widespread
recognition. This may be due to certain fruit qualities, such as thick skin
and seediness, that consumers find objectionable. The presence of seeds,
in particular, causes average consumers to overlook muscadines in favor of
seedless bunch grapes. To promote expansion of the muscadine industry,
the development of seedless cultivars has been a major goal of our
breeding program for the past six years.
Seedlessness does not occur naturally in muscadine grapes and must
be introduced, either by induced mutation of existing muscadine germplasm
or by transferring seedless genes from bunch grapes. Our program has
emphasized the introduction of bunch grape seedlessness.
Transferring seedlessness from bunch grapes is complicated by
genetic incompatibilities between the two; bunch grapes have 38
chromosomes whereas muscadines have 40. Most first generation hybrids
are sterile and set little or no fruit. Only after several generations of
crossing selected hybrids is good fertility obtained. The few existing
seedless muscadines that we have examined apparently derive seedlessness
from bunch grapes. These do not require fertilization to set fruit and,
therefore, cannot be used in breeding.
Potential expeditious approaches to overcoming these problems are
to utilize existing, fertile, muscadine-bunch hybrids that have been
developed in the past as parents or to develop protoplast fusion technology.
To date, progeny from crosses between the bunch-muscadine hybrids and
various muscadine cultivars have been recovered and are in primary field
tests. Field tests are conducted in order to: 1) select progeny with good
disease resistance and 2) evaluate fruit quality and yield. Additional
selections are made after three-to-four years from primary selections that
have disease resistance and have acceptable fruit quality. These selections
are increased by cloning and planted in replicated trials. From these trials,
progeny are ranked in order of resistance and quality after an additional
three-to-four years of growth and only the top few are selected. These are
then placed in collaborative regional field tests located at other IFAS
research centers, institutions such as Florida A&M University or
professional growers. Those that perform at a commercially acceptable
level are then released as new varieties. The first progeny from seedless
muscadine-bunch x muscadine hybrids will be evaluated at the primary
selection stage at Leesburg in 1992.
Micropropagation of Muscadines
Tissue culture micropropagation is used to produce large numbers
of disease-free plants. Micropropagation is useful when demand for plants
exceeds the supply that can be produced by conventional methods or when
plants particularly free of diseases are required. For example, muscadines
are reported to harbor endemic infections of Agrobacterium, a bacterium
that can cause devastating crown gall disease under certain climatic
conditions. In muscadines, crown gall can cause severe losses in vineyards
after freeze damage.
We recently developed a generally applicable procedure to
micropropagate muscadines and have tested it successfully on nine
To micropropagate muscadines, young shoot tips are removed from
vineyard plants during the Spring. Shoot tips are taken to the tissue
culture laboratory where the growing point (apical meristem) is surgically
removed and placed on a specialized culture medium. An abundance of
shoots form on the medium within about one month and are then
recultured to produce more shoots. Using this procedure, it is possible to
produce over 500,000 new shoots, which can be subsequently rooted into
plants, during a 30-week propagation cycle. Plants produced with this
procedure will be placed into collaborative field trials during Fall 91.
SEASONAL ACTIVITY OF GRAPE ROOT BORER IN FLORIDA
Susan E. Webb
The most serious insect pest of grapes in Florida is Vitacea
polistiformis, the grape root borer. This species belongs to a group called
the clearing moths (Family Sesiidae), which includes other damaging
pests such as peachtree borer and squash vine borer. In appearance the
grape root borer closely resembles another insect abundant in the vineyard
at this time of year, the paper wasp (Polistes). The lack of a characteristic
"wasp waist", differences in the shape of the antennae, and the presence of
wing scales distinguish the moth from the wasp.
The female grape root borer deposits her eggs on trunks and leaves
of both bunch and muscadine grapes (wild grapes are also an important
host). The hard, seed-like brown eggs fall to the ground and then hatch in
two to three weeks. This is the most vulnerable stage in the insect's life
cycle. The newly hatched larvae are tiny and can be attacked by ants,
spiders and other beneficial insects before they burrow into the soil in
search of a root. Keeping the soil surface directly under the vines free of
weeds should reduce the survival of the hatching larvae by exposing them
to the effects of sun and rain. For small plantings, a closely woven ground
cover (which allows passage of water but not weed growth) may prove
useful, especially if the material is pulled up tightly around the trunk to
prevent emergence of moths from below as well as entry of young larvae
Once the larva begins to feed, moving to larger and larger roots as
it grows, it is well-protected from both natural enemies and insecticides.
After two years (possibly one in some areas) the caterpillar makes its way
toward the surface and enters a pupal stage during which it becomes a
moth. The pupa moves the remaining distance to the soil surface. The
moth then breaks free and leaves the shiny, paper-thin, brown pupal skin
behind, often half-buried and upright near the base of the vine.
For the past three years, with the help of other scientists and grape
growers, we have been monitoring activity of male moths using a
pheromone, a specific chemical produced by the female as a calling signal
to the male. Our results show that from Gainesville south to at least Ft.
Myers, the peak period of activity for the adult moths is from late August
or early September to early October. August is the worst month for
growers farther north, from Freeport to Defuniak Springs to the
Tallahassee area. Presumably because of our mild climate, the borer has
an extended period of activity in Florida, lasting from August to December
in many locations on the peninsula.
Figure 1 shows trapping data from sites ranging from the Panhandle
to Miami. The characteristics of each location were quite different (size of
grape planting, varieties, distance from wild grapes) so total numbers
cannot really be compared between sites. For example, there were no
cultivated grapes at the trapping site in Miami. Timing of emergence,
however, can be compared from one location to another. Figure 2 shows a
gradually later emergence as the trapping location shifts southward from
Freeport to Leesburg. This is not a typical pattern for an insect. Being
cold-blooded, insects develop faster at warmer temperatures and one would
expect the moths to emerge earlier in the southern part of the state.
Figures 3 and 4 show data from 3 years of trapping near Quincy and
at the IFAS Agricultural Research and Education Center at Ft. Pierce.
The Quincy pattern is similar to what one finds in Georgia; Ft. Pierce is
unique in that a few grape root borers can be caught as early as late April
and as late as the following January.
If applying the only chemical insecticide that is registered for use on
grapes against grape root borer (Lorsban 4E), the best time to apply it is
during peak emergence. Only one application per year is allowed in
Florida and it must be at least 35 days before harvest. This regulation
limits application to after harvest of muscadine grapes for much of the
state. Fortunately this coincides well with peak moth activity. By clearing
the area under the vines at this time you will reap several benefits: good
contact of insecticide with the soil surface, reduced larval survival even if
insecticide is not used, and, if continued through leaf drop, removal of
litter under the vines will destroy overwintering pupae of grape leaffolder
I would like to thank the following people who helped collect the
information shown in the figures: Dr. Richard K. Sprenkel, NFREC,
Quincy; Dr. Jennifer L. Sharp, Director, USDA/ARS Subtropical
Horticulture Lab, Miami; Mike Fleming, Biologist, AREC, Ft. Pierce;
Foster Burgess, Alaqua Vineyards, Freeport; Tom Goldsworthy, O.N.E.,
Odessa; Robert Wallace, Chestnut Hill Nursery, Alachua; Peter Groves
and Dale Yadon, Biologists, CFREC, Leesburg.
0 10 20 30
May June July Aug Sept Oct Nov Dec
0 10 20 30
May June July Aug Sept Oct Nov Dec
S 40 1990
m 30 Quincy
5 15 25
June July Aug Sept Oct Nov
C 40' 1990
W 30- Ft. Pierce
Aay June July Aug gOpt Oct N30 De
CONTROL OF GRAPE DISEASES IN FLORIDA
D. L. Hopkins
With our long growing seasons, high temperatures, abundant
rainfall, and high humidity, grape diseases are very difficult to control in
Florida. Pierce's disease of grapevine, a xylem-limited bacterial disease,
has had the greatest impact on grape production in Florida; it prevents us
from growing European- and American-type bunch grapes. Hybrid bunch
grapes with resistance to Pierce's disease, or muscadine grapes, must be
grown. Fungal diseases are a serious problem, especially anthracnose on
bunch grapes. The lack of highly effective, economical to use fungicides
that can be applied throughout the season makes the more disease
resistant muscadines especially attractive to many grape growers.
Muscadines are resistant to anthracnose, but there are two fruit rot
diseases that must be controlled, bitter rot and ripe rot. The bitter rot
fungus invades the pedicels shortly after flowering, but does not move into
the berry until it reaches maturity. The infected berry becomes covered
with black fruiting bodies, shrivels, and becomes a dry black mummy. Fruit
are susceptible to the ripe rot fungus at all stages from small green berries
to ripe fruit, but they do not show symptoms until ripening. With both
fruit rots, frequent rains can result in severe crop loss.
Angular leafspot is an important disease of muscadine grapes that
causes premature defoliation, resulting in reduced plant vigor and yield.
Lesions first appear as small yellow flecks on the leaves and develop into
dark brown spots with yellow halos.
Muscadine diseases can be controlled by growing cultivars that are
more resistant to the diseases, by cultural practices such as removal of
mummies from the vine, and by fungicide applications. With muscadines,
the first fungicide application should be applied just prior to bloom.
Protective fungicides should be repeated at 2-week intervals through
harvest and one or two postharvest applications may be necessary for
angular leaf spot control. With some of the more resistant varieties, fewer
applications may still give control. The applications just prior to fruit
maturation are most important. Fungicides that may be used are listed in
the table that follows.
Bunch Grape Diseases
The most serious disease on bunch grapes is anthracnose, which
affects both foliage and fruit. Young, green succulent shoots are most
susceptible and growing points of shoots are often killed. Fruit symptoms
consist of whitish-gray lesions with a dark margin. Anthracnose is
especially damaging during years of heavy rainfall.
Isariopsis leaf spot causes premature defoliation after harvest when
spraying is discontinued. Leaf spots are irregular to angular, and become
black and brittle. Black rot can be a problem some years in Florida. The
major damage of black rot is on young immature fruit. Berries dry, shrivel,
and wrinkle until they become a hard black mummy. The entire cluster
may be affected. Downy mildew can be a problem on some cultivars. The
fungus attacks all parts of the vine, especially young leaves. A cottony
white growth characteristically occurs on the lower leaf surface.
With bunch grapes, a dormant season spray of a basic copper sulfate
or lime sulfur aids in the control of anthracnose. 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 after harvest.
Spray intervals should be shortened during weather and may be lengthened
during dry seasons. Fungicides that may be used are listed in the table that
FUNGICIDES FOR GRAPE DISEASE CONTROL
Anthrac- Black Bitter Ripe Angular Isariopsis Downy
Fungicide nose rot rot rot spot Leafspot Mi tdew
Benlate24 +++ +++ + + ++
Captan5 +++ +++ +++ ++ ++ ++ +
Copper fungicides + + + + + + +
Mancozeb6 ++ ++ ++ ++ ++ +++
Nova27 +++ ++ ++ ++ ??
1- = not effective, + = some activity, +++ = most effective, ? = not known.
2Trade names are given for these fungicides, others are common names.
3A maximum of 18 ounces of Bayleton 50WP may be applied per acre per season.
Preharvest interval (PHI = 14 days).
4pHI = 7 days.
5A maximum of 24 tbs. of Captan 50WP may be applied per acre per year.
Treated areas cannot be reentered for 4 days without protective clothing.
6Can not be applied within 66 days of harvest.
7A maximum of 1.5 tbs. of Nova 40W may be applied per acre per year. PHI = 14 days.
Limitations to Disease Control
With the currently available fungicides for grapes, it is difficult to
maintain a good spray schedule as you approach harvest time, especially if
you have varieties that ripen over an extended period. Of our most
effective fungicides, Nova has a 14 day PHI, Benlate has a 7 day PHI, and
Captan has a 4 day reentry period. This makes it difficult to use them
during the harvest period, and yet the fungicide application just prior to
fruit maturation is one of the most important ones. Mancozeb, one of the
most effective, broad-spectrum materials that we have, cannot be used
within 66 days of harvest. This makes this material useful only on non-
bearing vines, and in the very early season and after harvest on fruiting
vines. Copper materials can be used but they are generally less effective.
If downy mildew becomes a problem prior to harvest, we are very limited
in our choice of materials and cannot use the best material, mancozeb.
Careful planning to coordinate our spray schedule with our harvest
schedule is necessary if we are to harvest clean, marketable fruit.
GRAPE FIELD DAY VINEYARD TOUR
New grape progeny test area. Seedlings from embryo rescue project
are transplanted from the greenhouse into this block. Fruit should
be produced for preliminary evaluation in 3 years.
Irrigation pump and system will be demonstrated in a block of
'Alachua', a black muscadine released by CFREC-Leesburg in 1990.
Muscadine diseases and a potential new grape cultivar, Fla. AA12-3.
Pierce's disease, ripe rot, and bitter rot will be observed in
muscadine cultivars. Two vines of Fla. AA12-3 will be shown.
Pesticide sprayer will be demonstrated and the screenhouse where
Pierce's disease susceptible grapevines that are used in the breeding
program are grown are grown will be discussed.
P9-15, the muscadine-bunch grape hybrid that is a parent of Fla.
AA12-3, will be observed.
0 The Institute of Food and Agricultural Scences, University of
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Centers and 67 County Extension offices throughout the state.
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