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
MUSCADINE GRAPE FIELD DAY
UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
AGRICULTURAL RESEARCH AND EDUCATION CENTER, LEESBURG
Thursday, August 15, 1985
9:30 12 noon
Dr. Mary C. Halbrooks, Fruit Crops Department Moderator
9:30 10:20 Registration and muscadine grape cultivar fresh
fruit and juice taste paral (A1l people
attending are invited to rl fAci
breeding selections for ua rM
10:30 11:10 Presentations by AREC facultyA ~jUOd6't&S cur,r nt
research on grapes at Leesburg.
10:30 Dr. W. C. Adlerz, Entomologis A 'qr sect
Control on Florida Muscadine Grapes.
10:40 Dr. R. P. Bates, Food Scientist; Department of Food
Science & Human Nutrition. The Commercial Potential
of Florida Muscadine Grapes.
10:50 Dr. M. C. Halbrooks, Extension Horticulturist,
Viticulture; Fruit Crops Department. Survey of Cold
Damage in Muscadine Vineyards of Florida.
11:00 Dr. J. A. Mortensen, Geneticist; AREC Leesburg.
Breeding Muscadine Grapes for Florida.
11:15 noon A guided tour of the 17 acre research vineyard will
be conducted. Of special interest will be
experimental cultivars, a vineyard sprayer in
operation, an overhead arbor, maxi-jet irrigation,
and various trellising techniques.
Refreshments on tour courtesy of Abbott Lab
Leesburg AREC Research Report (LBG 85-2)
300 Copies
i1h Irnstibtiif ol I L)odl afld Aricu ltuiii Sci:IIenc is all Lqual L1iiploylleniit UL)(o)llltulity Atfrlliative Action Employer authorized to provide research,
ediucationral infloilation aniid other Selvici'e only to individuals arndl institutions that function without regard to race, color, sex, or national origin.
Insect Control on Florida Muscadine Grapes. (W. C. Adlerz)
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 soil 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 eggs 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 penetrating 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 4.5 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 1).
The Commercial Potential for Muscadine Grapes. (R. P. Bates)
With the development of improved muscadine cultivars and
cultivation practices the development of a commercial grape
industry is approaching practicality. Muscadine juice and wine
can be unique items with regional (and perhaps wider) appeal.
The technology of products as varied as vineyard cider to aseptic
packed juice with a long shelf life will be discussed. Also,
Florida has a good start in high quality muscadine wines, and
some interesting new wines are coming. In the case of all
muscadine products, including fresh grapes, quality marketing,
and economic considerations are paramount. We're competing with
other states and other fruits, beverages and wines in a highly
competitive market. Florida products need to be better than
good!
Table 1. 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 (Dog Ridge) 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
Higgins 4.0 0.0 0.7 2.7 2.3
1Average from 6 single-plant replications.
2Average from 5 to 15 plants of each variety.
Insect Control on Florida Muscadine Grapes. (W. C. Adlerz)
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 soil 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 eggs 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 penetrating 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 4.5 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 1).
The Commercial Potential for Muscadine Grapes. (R. P. Bates)
With the development of improved muscadine cultivars and
cultivation practices the development of a commercial grape
industry is approaching practicality. Muscadine juice and wine
can be unique items with regional (and perhaps wider) appeal.
The technology of products as varied as vineyard cider to aseptic
packed juice with a long shelf life will be discussed. Also,
Florida has a good start in high quality muscadine wines, and
some interesting new wines are coming. In the case of all
muscadine products, including fresh grapes, quality marketing,
and economic considerations are paramount. We're competing with
other states and other fruits, beverages and wines in a highly
competitive market. Florida products need to be better than
good!
Survey of Cold Damage in Muscadine Vineyards of Florida.
(M. C. Halbrooks)
Cold damage of muscadine grapes has been reported this year from
all areas of the state including a location as far south as Plant
City. No damage due to recent freezing temperatures of 1983 and
1985 has yet been reported on bunch grapes. Bunch grapes are
less susceptible to cold injury due to resistance carried down
from bunch grapes which evolved in the temperate regions.
Muscadine grapes, however, evolved in the humid subtropical
environment. Thus temperatures of 10 F can cause injury on even
fully dormant vines.
Symptoms of cold damage generally fall into one of 4 categories
which describe the affected portion of the vine. These are (1)
buds, (2) arms, (3) trunk, and (4) whole vine. Bud damage
appears:as lower percentage or uneven bud break, i.e. portions of
the arm leaf out irregularly or not at all leaving blank spaces
along the arm. Arm damage appears as the death of all new shoots
from a specific area along the arm length or the entire arm.
This type of damage is caused by a girdling effect of a ring of
dead tissue on the arm. Trunk damage appears as the death of new
shoots along all arms and is often characterized by the sprouting
of suckers from the area just below the ring of damaged tissue.
Splitting of the outer layers of the trunk may also occur due to
dehydration and shrinkage of the dead tissues.
Assessing the degree of damage to your vines immediately after
the cold period is difficult. Bud damage could be assessed by
cutting off portions of spurs and forcing-out the buds in warm
water indoors. Arm and trunk damage can sometimes be recognized
by a large water-soaked area of the bark which when peeled back
with a knife reveals gray, dark brown or black cambial tissue (in
order of increasing severity).
An accurate assessment of the degree of cold injury in the
vineyard often is not possible until early summer. Most often
these damaged vines will leaf out in the spring with the reserve
of water and carbohydrate in the wood. During this time the new
shoots will produce carbohydrates from photosynthesis but the
transport of these needed energy supplies to the roots will be
restricted by the girdled area. With the onset of hot summer
days leaves need more water than the reserve can supply and the
roots, now starving for lack of photosynthates from the leaves,
will be unable to take up water and nutrients. Thus the entire
vine may wilt and die within a few days. Suckers which sprout
from below the girdled area will be able to supply the roots with
needed energy supplies, possibly saving the plant. These new
shoots should be trained up or along the trellis wire to serve as
replacements for the dying arms or trunks.
The survey (see Table 2) taken in early summer of this year shows
that some cultivars are more susceptible to cold injury than
others. Fry, for example, is the least cold resistant cultivar;
5
while Dixie seems to be somewhat cold hardy. Factors which may
predispose vines to cold damage are (1) late season fertilization
and irrigation, (2) excessively large crops which are low in
sugar, and (3) cold damage from the previous winter. The most
vulnerable area of the vine is the southwest portion of the
trunk. Results of this survey and a follow up survey of more
detail will be compiled with other states of the southeast as
part of a regional project and will include information on
cultivars, location, management practices and degree of injury.
It will be the First of its kind for the southeast and should
allow us to make better recommendations to you in the future.
Table 2.
CULTIVAR
Fry
Fry
Fry
Fry
Fry
Fry
Carlos
Carlos
Triumph
Jumbo
Cowart
Magnolia
Noble
Dixie
Survey of cold-damaged vineyards in Florida, 1985.
PORTION OF VINE AFFECTED
arm, trunk
arm
all
partial buds, arm, trunk
partial buds, arm
partial buds, arm
arm, upper trunk
arm
arm, upper trunk
arm, upper trunk
all, 2 arms
arm, split trunks
arm
partial buds/arm
PERCENTAGE
20%
10%
<10%
25%
<10%
20%
20%
<10%
<10%
<10%
<10%
<10%
< 5%
COUNTY
Hillsborough
Alachua
Alachua
Walton
Jefferson
Gadsen
Hillsborough
Walton
Hillsborough
Hillsborough
Hillsborough
Alachua
Hillsborough
Walton
Breeding Muscadine Grapes for Florida.
(J. A. Mortensen)
It was 1959 when we began testing muscadine cultivars and
selections obtained from breeding programs in Mississippi,
Georgia, and North Carolina. We have continued testing and
evaluating available muscadine material to date for longevity,
fruit yields, disease resistance, and adaptability to mechanical
harvest. Since 1972 we have made crosses at Leesburg to increase
emphasis on resistance to PD, uniformity of ripening, high
percentage dry scar, and fruit quality for fresh use or wine.
Increased berry size is demanded by pick-your-own and fresh
market outlets; thus, larger-berried parents such as Fry, Summit,
or Triumph have been used as sources of size. Seedlessness is
needed in muscadines, and at least one seedless selection
developed by the late Mr. B. O. Fry of Griffin, Georgia is
currently of interest. Use of fertile hybrids between bunch and
muscadine grapes to transfer seedlessness from bunch grapes to
muscadines is under investigation. Wine cultivars with good
color and quality retention through fermentation are being
developed in cooperation with Dr. Bates. Resistance to berry rot
during the period of ripening has received increased selection
pressure in recent years among our muscadine selections.
Table 3 gives the currently recommended muscadines for various
purposes and uses, along with fruit yields obtained at Leesburg.
Best for white wine are Welder, Doreen, and Dixie; for red wine
Noble and Regale. Best pick-your-own bronze-fruited varieties
are Triumph, Dixieland, Summit, Fry, and Dixiered. The best
pick-your-own black-fruited variety is Nesbitt, a new cultivar
from North Carolina Experiment Station, which will likely replace
Jumbo and Cowart for this purpose, Only two cultivars appear
suitable for fresh market: Nesbitt and Summit. Other varieties
either lack size, ripen unevenly, or have a wet stem scar when
harvested mechanically.
Table 4 lists the 30 muscadine varieties not currently
recommended for Florida and the reasons why they are not. Carlos
is excellent for uniformity of ripening and dry stem scar but
several vines have died of PD at Leesburg and at other Florida
ct'ions. PD susceptibility 1. tLh-
Carlos. Magnolia makes good white wine but the fruit ripens so
unevenly in Florida, and its susceptibility to ripe rot is so
evident that we cannot recommend it. Higgins was a fine old
female variety but susceptible to ripe rot, so is no longer
recommended. Sugargate has excellent fruit quality but yields so
poorly it is not recommended (See Table 4).
Below are listed 12 newer muscadine selections from our breeding
program that are being tested around the state as possible new
varieties for Florida growers.
Fla. AA10-9 A cross of Southland with Dixie, black, with 4.6 g
berries, 87% dry scar, ripening uniformly about August 18 in
Leesburg, with 36 g bunches averaging 8 berries per cluster that
do not shell off readily. Vine vigor medium, productive.
Possible wine or juice grape.
Fla. AA12-3 A cross of Summit with Florida P9-15; black, with
6.3 g oval berries, dry scar, ripening uniformly about August 16,
with,good flavor but slightly tough pulp. Leaf shape resembles
bunch x muscadine hybrids. Vine vigorous and productive, with 37
g clusters averaging 6 berries per cluster. Possible wine or
juice grape.
Fla. AA12-64 A cross of U.S.4, a uniform ripening black
selection, with Florida AD3-42, a highly productive bronze
selection derived from a Carlos x Welder combination. Fruit is
black, with 6.4 g berries and 49 g clusters averaging 8 berries
per cluster.* Scar is relatively dry. Fruit ripens uniformly
about August 17, with high levels of productivity and vine vigor.
Bloom is early and probably should be harvested about August 10
or 12 for wine use.
Florida AB5-60 A cross of Magoon with Dixie, pink fruited, with
8.4 g berries on 65 g clusters averaging 8 berries per cluster.
Relatively dry scar and less rot than the usual bronze-fruited
variety. The selection has excellent vigor and productivity,
with good-flavored fruit, but pulp is too tough for fresh market
use. Ripens about August 25, possibly useful for wine.
Florida AD2-38 A cross of Nesbitt with Carlos, black, with 8.3 g
berries on 46 g clusters averaging 5 berries per cluster.
Relatively dry scar, productive, ripening about August 22 with
good-flavored fruit that may be of interest for pick-your-own,
dooryard, or fresh market.
Florida AD3-42 A cross of Carlos with Welder, bronze, with 5.3 g
berries on 40 g clusters averaging 7.6 berries per cluster. Scar
is occasionally wet when harvested mechanically but ripening is
uniform about August 16, with highly productive, vigorous vines
at several locations across Florida. Quality of fruit is juicy
and very good, but berries probably are smaller than desired for
fresh market. Very resistant to diseases. Possible use for wine
or dooryard.
Florida CA4-46 A cross of Fla. H13-11 (a Vitis munsoniana x
Magoon combination) with Dixie. Fruit is black, with 4.4 g
berries on 72 g clusters averaging 17 berries per cluster..
Flavor is good and clusters are well-filled with juicy berries
that are highly pigmented. Vines have excellent vigor and
production, ripening uniformly about August 27 with pH 3.3,
titratable acidity of .42, and soluble solids of 16.6%. A
natural for red wine production.
Florida CA9-37 A cross of Fry with Southland. Bronze fruit with
11.3 g berries on 75 g clusters averaging 6.5 berries per
cluster. This selection is a female and will require a
self-fertile pollinator nearby. Fruit quality resembles Fry but
picks with a relatively dry scar. Vine vigor and productivity
are medium. Possible use for pick-our-own or fresh market.
Florida CA9-48 Another cross of Fry with Southland. Fruit is
black, with 7.7 g berries on 51 g clusters averaging 7 berries
per cluster. Vines are vigorous and productive, ripening
uniformly about August 27. Fruit is good flavored with chewable
skin and tender pulp. Scar is about 50% dry. It is a natural
for pick-your-own and dooryard use.
Florida CA9-50 Still another Fry by Southland cross with bronze
fruit, 6.6 g berries on 38 g clusters averaging 6 berries per
cluster. Both the texture and flavor of the fruit is good to
excellent. Vine vigor and productivity are very good, ripening
fruit uniformly about August 27 at Leesburg. Usually 70% of the
fruit have dry stem scar when harvested mechanically. Potential
is for fresh market, wines (ph 3.4, titratable acidity .37,
soluble solids 18.3%), and dooryard use.
Florida DBl-65 A cross of Southland with Carlos. Fruit is
black, with 5.6 g berries on 44 g clusters averaging 7.6 berries
per cluster. This selection ripens uniformly, with 93% dry scar,
good texture, and very good flavor. Vines have medium vigor and
productivity, ripening about August 27 at Leesburg. Possible
fresh market or wine use.
Florida DB3-21 A cross of Southland with Dixie, black fruited,
with 6.0 g berries on 41 g clusters averaging 6.6 berries per
cluster. Fruit ripens uniformly with 95% dry scar, 18.8% soluble
solids, pH 3.3, and titratable acidity of. .46. Pulp too tough
for fresh fruit. Possible wine or juice grape.
Table 3. Fifteen muscadine varieties currently recommended for
Florida for specific uses (5 for wine, 7 for
pick-your-own, 2 for fresh market, 3 for juice, and 7
for dooryard use).
Bronze-fruited
Dixie
fDixie and
Dixiered
poreen '
Fry (female.)2,
'Summit, (female),
Triumph l
S Welder
Black-fruited
Albemarle
Cowart
Jumbo (female)
Nesbitt
Noble
Regale
Southland
Uses1
wine, DY
PYO
PYO
wine, DY
PYO
PYO, fresh
PYO, DY
wine, juice
DY
DY
PYO
PYO, fresh, DY
wine, juice
wine, juice
DY
Tons/acre
6.0
5.5
7.1
6.8
4.1
3.6
7.2
6.0
,4.7
4.9
5.1
4.5
8.1
8.9
5.2
1Uses: PYO = pick-your-own, DY = dooryard.
Female varieties require a self-fertile variety nearby for good
fruit set. Self-fertile varieties bear fruit well without a
different variety nearby.
Juice of Welder should be blended with Noble or Regale to impart
red color.
Table 4.
Muscadine grape varieties not recommended for new
plantings in Florida.
Bronze muscadine grapes
Reason not- recoinirin[lde(c
Carlos
Chowan
Dearing
Georgia Red
Higgins
Lucida
Magnolia
Nevermiss
Pamlico
Pink Hunt
Redgate
Rich
Roanoke
Scuppernong
Sterling
Stuckey
Topsail
Watergate
Yuga
susceptible to PD
low fruit yield
low fruit yield
lacks quality
fruit rots, uneven ripening
susceptible to PD
uneven ripen, fruit rots
low yield, lacks quality
low yield
lacks quality
lacks quality, tight bunch
low yield
low yield
low yield, susceptible to PD
lacks vine vigor
low yield
low yield
low to medium yield
small berry,tenacious
Black muscadine grapes
Bountiful
Chief
Creek
Dulcet
Diplin
Hunt
Magoon
Pride
Scott Imperial
Sugargate
Thomas
fruit shells off on ground
small size, low yield
lacks sugar, low yield
low yield, tenacious
lacks quality and yield
low yield,dry calyptra
small size, weak vigor
susceptible to PD
small size, female
susceptible to PD, low yield
lacks flavor
Use of Tissue Culture for Production of Grape Varieties Adapted
to Florida. (D. J. Gray)
Tissue culture-related research is being conducted in order to
expedite the establishment of improved grape varieties adapted to
Florida. Three distinct research projects currently underway are
discussed below.
Rapid Micropropagation of Economically Important Varieties.
The potential of grape as an alternate crop on surplus frozen
citrus land suggests that the need for desirable planting stock
may increase rapidly. It may not be immediately possible for
nurseries to meet this need. Tissue culture micropropagation is
a method that can be used to produce plants at a rate far in
excess to what is currently possible in grape nurseries.
The micropropagation technique is relatively straight forward.
Shoot tips are introduced into culture and are induced to branch
prolifically. Each branch is either removed and rooted,
producing a single plant, or is induced to produce more branches.
Thus, a continuously branching culture is maintained and new
plants harvested as needed. We have, to date, established 28
species, hybrids and/or cultivars in this culture system.
Muscadine cultivars 'Carlos', 'Dixie', 'Marsh', and numbered
selection AD3-42 as well as muscadine-bunch grape hybrids NC35-4,
NC39-1 and P9-15 have been successfully cultured. Some respond
very well, whereas others branch less often. Ongoing research in
this area will concentrate on optimizing micropropagation
methodology for our most promising cultivars.
Rescue of Progeny From Seedless x Seedless Crosses.
Conventional breeding of seedless grapes is complex and tedious
because crosses between seedless cultivars do not yield viable
seeds. To circumvent this problem, breeders now cross seeded
with seedless lines hoping to recover a seed that ultimately
produces a seedless vine. This process typically takes ten or
more years to accomplish. Using tissue culture, it is possible
to rescue the young seed from seedless x seedless crosses and
promote the development of normal plants. In this manner, the
seedless trait is concentrated within one breeding cycle. Plants
are produced in a few months and then field tested. Total
development time is estimated to be four years.
To date, we have cultured approximately 6,000 embryos in a
specific medium-growth regulator regime. These embryos are the
results of controlled pollinations between various seedless
lines. The culture period is still in progress and we are
waiting to determine the results of our efforts.
Selection of Pierce's Disease Resistant Mutants.
Pierce's disease (PD) is the major factor limiting the
establishment of high quality European and North American grape
varieties in the Southeast. All bunch grapes currently grown in
Florida are the product of crosses between these quality PD
susceptible grapes and low quality but resistant native grapes.
The breeding that this entails has taken a very long time because
repeated crossing and evaluation are needed to ultimately select
a vine that retains the quality of one parent with only the
resistance of the other.
Plant tissue culture offers the opportunity to completely
circumvent the conventional approach by selecting resistant
mutations directly from quality grape varieties without use of
native species. In this approach, cultures containing large
populations of spontaneously mutating cells are challenged with
PD toxin. Only those rare mutant cells resistant to toxin are
able to survive and grow. Eventually cultures composed
completely of resistant cells are produced. If a high quality
but susceptible variety is used as the culture source, an
identical, high quality but now resistant cultivar is the result.
Therefore, the best European and American cultivars could be
expeditiously introduced into Florida without conventional
breeding.
Development of this system is one of the long term research goals
of our program. Several separate requirements must be met in
order to be successful. Although grape micropropagation as
described above is routine, regeneration from single cells is
much more difficult. Methodology to standardize toxin extracts
must also be developed, although it is now known that crude
extracts inhibit cell cultures. Thus far, we have obtained
regeneration from single cells of only one species, Vitis longii.
This. is a native grape from the Texas-Oklahoma region and has no
economic use in Florida. However, this species is susceptible to
PD so that we can use it in advanced experimentation on resistant
mutation selection until we develop cultures of more desirable
grapes.
Pierce's Disease of Grapevine. (D. L. Hopkins)
Pierce's disease (PD) is caused by a small, xylem-limited
bacterIia. 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 muscad.ne'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'.
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