Historic note
 Front Cover
 Grape breeding update on varietal...
 Grape biotechnology program
 Current research on grape...
 Control of grape diseases...
 Seasonal activity of grape root...
 Grape field day vineyard tour
 Back Cover

Group Title: Bunch grape field day, Central Florida Research and Education Center, Leesburg
Title: Bunch grape field day. 1993.
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00076044/00005
 Material Information
Title: Bunch grape field day. 1993.
Series Title: Bunch grape field day.
Physical Description: Serial
Language: English
Publisher: Central Florida Research and Education Center, University of Florida
Publication Date: 1993
Spatial Coverage: North America -- United States -- Florida
 Record Information
Bibliographic ID: UF00076044
Volume ID: VID00005
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 144618190

Table of Contents
    Historic note
        Unnumbered ( 1 )
    Front Cover
        Front Cover
        Page 1
    Grape breeding update on varietal improvement with conventional methods
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
    Grape biotechnology program
        Page 7
    Current research on grape diseases
        Page 8
        Page 9
    Control of grape diseases in Florida
        Page 10
        Page 11
    Seasonal activity of grape root borer in Florida
        Page 12
        Page 13
        Page 14
        Page 15
    Grape field day vineyard tour
        Page 16
    Back Cover
        Back Cover
Full Text


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

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida


August 19, 1993

AUG $0. 1993

University i.. lorida

Dr. D. L. Hopkins, Assistant Center Director

Central Florida Research and Education Center Leesburg

Iihuiile a Foodi d Ariculhual Sklamc

Leesburg CFREC Research Report LBG 93-2

Equal Opportunity/Affirmatve Action Institution



Central Florida Research and Education Center, Leesburg
IFAS, University of Florida

August 19, 1993

Dr. Tim Crocker, Extension Horticulturist, Horticultural Sciences

9:00 Registration, tickets available for catered lunch, and participation in fresh fruit
taste panel of grape cultivars and selections

9:15 Wine/Juice making demonstrations by Bob Bates & Charles Sims, Food
Science & Human Nutrition Gainesville

Jelly/Jam making demonstration by Deborah Boulware, Extension Home
Economist Lake County

Grape Biotechnology display by D. J. Gray and Staff CFREC Leesburg

10:00 Welcome, Dr. Charles A. Conover, Center Director CFREC, Apopka
10:05 James W. Harris, Senior Laboratory Technician CFREC, Leesburg
10:15 Dr. Dennis J. Gray, Developmental Biologist CFREC, Leesburg
10:25 Dr. Donald L Hopkins, Plant Pathologist CFREC, Leesburg
10:35 Dr. Susan E. Webb, Entomologist CFREC, Leesburg
10:45 Dr. Charles Sims, Enologist Food Sci. & Human Nutr., Gainesville

11:00 Walking tour of vineyards to observe research and cultivars

11:15 Wine/Juice making demonstrations by Bob Bates & Charles Sims, Food
Science & Human Nutrition Gainesville

Jelly/Jam making demonstration by Deborah Boulware, Extension Home
Economist Lake County

Grape Biotechnology display by D. J. Gray and Staff CFREC Leesburg

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.


J. W. Harris
Sr. Lab Technician

Three new cultivars of grape were released in the fall of 1992, each one having
different uses.

A new bunch grape originating from a cross between Dog Ridge and Tampa has
been released as 'Florilush' a grape rootstock for Florida. It was tested as CD9-81 since
1979. Dormant cuttings of Florilush root readily in container or field nurseries. When
bench grafted, Florilush had over 90% successful unions and greater scion vigor than
Dog Ridge or Tampa (Table 1). When used in bench grafting, it has high percentage of
successful unions with scions and has a higher root growth and foliage vigor than other

Less root damage from grape root borer has been observed in vineyard plantings of
"'rilush than in Dog Ridge or Tampa. In inoculated plants in pots, there was
'"cantly less damage in Florilush than in Tampa.

Florilush is resistant to Pierce's disease (Xylella fastidiosa), anthracnose (Elsinoe
ampelina), downy mildew (Plasmopara viticola), powdery mildew (Unicinula necator), and
Isariopsis leaf blight. It has high tolerance to nematodes that has been demonstrated by
100% replant survival in the vineyard and by planting into heavily infested nematode
areas without general symptoms. Principal nematodes in replant sites were
Criconemoides, Belonolaimus, Meloidogyne, and Trichodorus.

Table 1. Successful graft unions, vigor, scion growth weight and rootstock
root weight for Florilush compared to Dog Ridge and Tampa with Orlando
Seedless as the scion three months after bench grafting.
Graft unions Scion growth Rootstock root
Variety (%) Scion vigorz wt(g) wt/(g)
Dog Ridge 64.0 3.5 36.9 19.8
Florilush 92.0 3.7 41.4 17.7
Tampa 96.0 2.1 20.8 7.6
ZScion vigor: 0 = dead; 5 = highly vigorous

A new interspecific-hybrid grape originating from a cross between Summit and
Fla. P9-15, has been released as 'Southern Home' primarily for use as an ornamental
dooryard grape with adaptability to the South. It was tested as Fla. AA12-3 since 1981.

Black muscadine varieties presently used for dooryard have little, if any, ornamental
value. However, this interspecific-hybrid (part bunch grape and part muscadine) is
unique in appearance because of its leaf shape with very deep-cut sinuses resembling
that of a maple leaf. It has potential as a dooryard grape that could be grown on arbors
around patios and as borders on fences throughout the South.

Fruit is comparable to that of Cowart or Albemarle and breaks up easily when
chewed. Berries ripen uniformly with a few late blooms ripening into October or
November. The picking scar is moderately dry and soluble solids are similar to other
varieties (Table 2).

Symptoms of Pierce's disease have never been observed in Southern Home at
Leesburg. It is fully resistant to ripe rot (Glomerella cingulata), bitter rot (Melanconium
fuligineum), and black rot (Guignardia bidwellii). It is also completely resistant to
anthracnose (Elsinoe ampelina) and downy mildew (Plasmopara viticola). Late season
diseases such as angular leaf spot (Mycosphaerella angulata) may occur on Southern
Home but in such small amounts that fungicide application may not be warranted.
Southern Home may not need a regular preventive fungicidal spray program except in
areas of heavy disease pressure.

Table 2. Flower type, percentage dry scar, berry size, soluble solids, type
of ripening, and level of disease resistance for Southern Home compared
with other black muscadine varieties at Leesburg and Monticello,
Dry Berry Soluble Type
Scar Size Solids of Disease
Cultivar Flowerz (%) (g) (%) Ripening Resistance
Leesburg Tests
Southern Home SF 64.4 6.7 18.2 Even Excellent
Alachua SF 74.0 7.5 18.0 Even Very good
Albemarle SF 82.9 5.8 19.2 Even Good
Cowart SF 15.0 7.2 17.6 Uneven Good
Nesbitt SF 31.6 9.8 17.2 Uneven Good
Monticello Tests
Southern Home SF 97.5 6.8 19.1 -
Alachua SF 98.0 8.0 17.7
Loomis SF 70.0 9.8 15.1 -
zSF = self fertile
Y- = not evaluated

A new muscadine grape originating from a cross between Triumph and AD3-42 was
released as 'Florida Fry' for grower trial primarily as a fresh fruit cultivar. It was tested
as Fla. AA7-44 since 1985.

The firmer than usual muscadine texture with its edible skin should be appealing to
patrons of U-pick grapes. The extended ripening of Florida Fry is appealing to growers
since they can market the fruit over a longer period of time. Florida Fry is self fertile
with yields appearing to be very good, and should be better than Fry, although vines are
only moderate in vigor. It picks with a high % dry scar and is disease resistant
(Table 3). Symptoms of Pierce's disease (Xylella fastidiosa) have never been observed in
Florida Fry plants at Leesburg. It is resistant to ripe rot (Glomerella cingulata), bitter rot
(Melanconium fuligineum), and black rot (Guignardia bidwellii). In common with most
muscadine varieties it is also highly resistant to anthracnose (Elsinoe ampelina) and
downy mildew (Plasmopara viticola). Late season diseases such as angular leaf spot
(Mycosphaerella angulata) may occur on Florida Fry but can be controlled by fungicides.

Table 3. Flower type, percentage dry scar, berry size, soluble solids, type
of ripening, and level of disease resistance for Florida Fry compared
with 4 bronze muscadine varieties grown for fresh fruit consumption.
Dry Berry Soluble Type
Flower Scar Size Solids of Disease
Variety Typez (%) (g) (%) Ripening Resistance
Florida Fry SF 75.0 9.9 20.9 Uneven Very good
Fry F 43.3 11.0 18.0 Uneven Fair
Triumph SF 90.0 9.0 17.9 Uneven Good
Dixieland SF 20.0 9.6 18.0 Uneven Good
Summit F 82.0 9.6 18.7 Even Good
zSF = fertile; F = female, requiring pollinizer

Other elite selections (those judged by the breeder to have promise for testing as
new cultivars) of bunch grapes include:

Fla. AN2-36 (BD10-51 x Lakemont) a seedless selection that is very similar to
Orlando Seedless, but is resistant to anthracnose.

Fla. BN6-85 (DC1-39 x Himrod) a seeded fresh fruit selection with berries
weighing up to 5.0 grams each.

Fla. CN7-89 (DC1-39 x Lakemont) a seeded fresh fruit selection with good disease

Fla. CA8-15 (Villard Blanc x Kissimmee Male) a wine and juice selection with
good pigment stability and excellent disease resistance including anthracnose, the
number one fungal problem for bunch grapes in Florida.

A large number of elite selections have emerged from the muscadine breeding
program including two new seedless varieties (Fla. AA9-2 and Fla. AA10-36). Other
characteristics such as large clusters and firm texture with edible skin are beginning to
develop. Table 4 describes 8 muscadines for use as seeded table grapes and Table 5
describes 5 muscadines for use as wine and juice grapes.

Table 4. Number of years tested at Leesburg, color of fruit, cluster weight,
berry weight, soluble solids, pulp texture, skin texture, flavor,
percentage dry scar, and vine vigor for 3 released varieties and 5 elite
selections of muscadine for use as table grapes.
Cluster Berry Soluble Dry
Years Fruit wt wt Solids Pulpz Skinz Scar Vine
Cultivar Tested Color (g) (g) (%) Texture Texture Flavorz (%) Vigor
Alachua 15 bk 53 7.5 18 5 1 6 74 med
Florida Fry 8 br 71 9.9 21 8 4 9 75 med
Fry 20+ br 78 11.0 18 4 2 7 43 hi
AA7-52 5 br 119 14.1 18 6 6 9 '70 hi
AA13-2 6 br 36 10.0 23 4 4 9 -35 hi
AN11-53 3 br 95 12.0 16 6 5 8 10 hi
CA3-60 5 br 89 11.9 18 3 4 6 93 hi
CA6-3 3 bk 97 11.3 23 3 2 8 23 hi
ZTexture and flavor ratings: 1 = poor; 3 = fair; 6 = good; 8 = very good;
10 = excellent.

Table 5. Number of years tested, fruit color, cluster weight, berry
weight, soluble solids, percentage dry scar, pH, titratable
acidity, and vine vigor for one commercial and four elite
selections of muscadine for use in making red wine and juices.
Cluster Berry Soluble Dry
Years Fruit wt wt Solids Scar Titratable Vine
Cultivar Tested Color (g) (g) (%) (%) pH Acidity Vigor
Noble 23 bk 37 3.0 18 23 3.6 0.27 hi
AN4-1 5 bk 95 4.3 16 63 3.0 0.82 hi
AN5-92 5 bk 82 4.5 16 67 3.0 0.92 hi
AN6-61 5 bk 114 6.0 15 80 3.6 0.65 hi
CA5-66 5 bk 112 10.0 15 73 3.8 0.41 hi

Bunch Grape Breeding

With more pesticides being removed from the market and more restrictions on the
use of remaining pesticides, it has become necessary to place emphasis on screening
bunch grape crosses for disease resistance before being planting them in the field. Once
seedlings make it past that first step, evaluations in the field are very strict to separate
susceptible and resistant seedlings, and susceptible ones are removed. Some of the
qualities that are being bred into resistant varieties are pigment stability, seedlessness,
and high quality, including thinner skin.

Muscadine Breeding

A new area of emphasis is the development of firm textured muscadine cultivars.
The skin of these new muscadines can be eaten with the flesh. We currently have this
characteristic in seeded muscadine. Attempts are being made to combine this
characteristic with seedlessness. A seedless muscadine variety would be a tremendous
boost to the Florida grape industry. If a large, seedless muscadine with firm texture and
an eatable skin is developed, and these traits are all available in our germplasm, an
entirely new market for grapes in Florida would emerge.

Also being developed are wine and juice cultivars with much larger clusters with the
possibility of greatly increased yields.


Dennis J. Gray -<
Developmental Biologist

In 1984, a special legislative appropriation established a biotechnology research program
for grape at the University of Florida. The program was designed to apply state-of-the-
art technology in order to accelerate grape development. Over 21 scientists, including
technical staff, students, postdoctoral research associates and visiting scientists have
participated in the program during the last nine years. Our research has already resulted
in tangible technology that has been made available to the industry. However, the most
significant benefits to come from our research will occur in the future when ongoing
projects are completed. Several of the completed and ongoing research projects are
presented at our field day exhibit table including:

At the request of the grape industry, methodology for rapidly producing disease-free
plants was developed for Florida Bunch and Muscadine grapes. The system for
muscadines represented a breakthrough for this crop. Micropropagation is now an
available tool for the industry and can be used to supply disease-free plants to meet
any conceivable demand.

Embryo Rescue
Embryo rescue technology was adapted to advance the breeding of seedless Florida
Bunch and Muscadine grapes. This technique, in which young embryos are
surgically removed from seedless fruit, has resulted in over 2,000 progeny. These
progeny have been in vineyard tests since 1986. Some hybrids between Bunch and
muscadine cultivars appear promising in these tests.

Cell Culture
Since 1985, we have been developing culture systems that allow complete grape
plants to be regenerated from single cells. These systems are essential for the
continued development of advanced grape improvement technology explained below.
Please see the examples at our exhibit.

Cell Fusion
We are attempting to fuse regenerative cells of seedless bunch grapes with
muscadine grapes, with the goal of producing seedless muscadine-like hybrids. With
proper cell systems already in place, fusion research is ongoing.

Genetic Engineering
We are using our cell culture systems as the basis for genetic engineering research.
Our goals are to eventually add genes for disease resistance into desirable varieties,
without breeding. With this approach, we might eventually be able to add genes for
Pierce's disease resistance and be able to grow vinifera-type grapes in Florida. Our
"gene gun" that is used to "shoot" genes into grape cells will be on display at our


D. L Hopkins
Plant Pathologist

Effect of Canopy Management on Disease Control.

This research is being done to evaluate the effect of leaf removal around fruit
clusters and summer pruning on disease control in 'Blanc Du Bois' under two different
cultural regimes. In one regime, the area under the rows was cleaned to bare soil, weeds
were pulled and pruning debris was raked and removed. In the other cultural regime,
only the large pieces of pruning wood were removed. In both cultural regimes, the
following canopy management treatments were evaluated: (A) Removal of 5-6 leaves
around each cluster; (B) Summer pruning of long, drooping shoots to allow airflow under
the vines; (C) Standard practice, no leaf removal or summer pruning; and (D) Removal
of 5-6 leaves around each cluster plus summer pruning. All plots in both tests received
the same pesticide applications. Fungicides used were Manzate 200, Captan, and Nova.


The cultural regime including bare soil under the vines reduced foliar anthracnose
symptoms early in the season and could be beneficial in grape disease control.

Leaf removal around clusters was very laborious and did not improve either
anthracnose or fruit rot control; therefore, it does not seem worth the effort.

Summer pruning to allow better air flow under the vines reduced fruit rot (primarily
bitter rot) and appears to be a desirable canopy management practice.

Screening for Anthracnose Resistance in Bunch Grapes.

Anthracnose is especially severe to grapevines grown in warm, humid climates, such
as Florida. Frequent fungicide applications are necessary to control the disease on
bunch grapes in Florida; however, the number of fungicides available is diminishing and
the trend will likely continue. Resistance to anthracnose is one of the big advantages
that muscadine grapes have in the South. For breeding, resistance to anthracnose is
available in bunch grape species native to the humid Southeast. Screening for resistance
to anthracnose is currently done by planting the progeny out in the vineyard and rating
symptoms from natural infection during the summer months. This process takes several
years and is very costly and inefficient.

The objective of this work is to develop a rapid, greenhouse screening method to
select the resistant progeny while seedlings are very young. This would allow us to
discard the undesirable, susceptible progeny very early in the process. To develop the
screening procedure, we are using seed from selfed 'Blue Lake' ,which segregates into a

3:1 ratio of resistant to susceptible, and selfed 'Lake Emerald', which segregates into
approximately a 1:2 ratio. Variables that are being studied in the screening tests include
spore concentration, temperature, and time in the moist chamber.

Preliminary Conclusions:

Greenhouse screening for resistance to anthracnose can be used to select resistant
grape seedlings in the 2-3 true leaf stage.

Temperature affects the length of time that the inoculated seedlings need to be in
the moist chamber.

Procedure has been used to select a few resistant progeny in the breeding program,
but additional data relating test conditions to field resistance is needed.

Induced Resistance to Pierce's Disease of Grapevine by Weakly Virulent Strains of
Xylella fastidiosa.

Pierce's disease, caused by Xylella fastidiosa, is primarily responsible for the failure
of bunch grapes (Vitis vinifera and Vitis labrusca) in Florida. Virulence of X. fastidiosa
strains to grapevine varies from highly virulent to avirulent. Avirulent isolates are able
to colonize grapevine but not systemically. Weakly virulent isolates colonize systemically
but more slowly than highly virulent isolates and produce only minor symptoms in the

In the greenhouse, avirulent and weakly virulent strains of X. fastidiosa were used to
inoculate two of the lower internodes of rooted cuttings of V. vinifera 'Carignane' with
105-106 bacteria per inoculation site. The challenge inoculation with a highly virulent
strain was done 2 weeks later into a single internode.

Conclusions and Discussion

Challenge inoculation of plants that had been protected with a weakly virulent strain
of X. fastidiosa resulted in a lower incidence and severity rating for Pierce's disease
than plants that had not been protected. Avirulent strains were ineffective in these
cross-protection tests, therefore, systemic colonization may be necessary for induced
resistance to occur. Hopefully, induced resistance by mild strains of the Pierce's
disease bacterium may provide a means of growing susceptible grapevines in
Florida. However, these results were obtained in pots in the greenhouse and
experiments were only 6 months in duration.

To determine whether cross-protection might work in the vineyard, we have
established a replicated test. We are using the susceptible bunch grape variety 'Himrod'.
Four different strains of X. fastidiosa are being evaluated as protectants. The vines were
inoculated with the protectant strains and transplanted into the vineyard to evaluate their
response to natural infection with the bacterium over several years.


.^. D.L. Hopkins
eo Plant Pathologist

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.

Muscadine Diseases
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
ot 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 follows.

Anthrac- Black Bitter Ripe Angular Isarfopsis Doey
Fungicide nose rot rot rot spot teafspot Nildew

Bayleton2,3 +++ .
Benlate2,4 4++ +4+ ++ + ++ ++
Captan5 ++4 4+ ++4 ++ ++ ++4
Copper fungicides + + + + + + *
Mancozeb6 ++ ++ ++ + + ++ 4+
Nova2'7 +4 ++ ++ 4 ++ ? ?
= 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 50OP may be applied per acre per season.
Preharvest interval (PHI = 14 days).
4PHI = 7 days.
5A maximum of 24 lbs. of Captan 50WP may be applied per acre per year. (PHI = 14 days)
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 ibs. 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 14 day PHI and 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.


j(L/ 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 from above.

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 (Desmia funeralis).

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.

Figure 1



0 10 20 30
May June July Aug Sept Oct Nov Dec

Figure 2

S 50

M 40
Cc 30
( 20


0 10 20 30
May June July Aug Sept Oct Nov Dec

Figure 3


n40 1990
S1-a--- 1988
m 30- Quincy

< 0

5 15 25
June July Aug Sept Oct Nov

Figure 4

S40 -- 1990
S--- 1989
S 1 -0-- 1988
m 30- Ft. Pierce

< o
) 20 2

6 10 1 30
0ay June 1uly Aug e Nov Dec

Aay June 1uly Aug Opt Oct N30 Dec



Stop 1

Disease symptoms on 'Blanc Du Bois', including anthracnose, downy mildew and
mild Pierce's disease.

Stop 2

Germplasm block, consisting of native grape species and other germplasm used in
grape breeding program.

Stop 3

Field screenhouse. Pierce's disease susceptible grapevines used in the breeding
program will be discussed.

Stop 4

'Southern Home', an interspecific, muscadine-bunch grape hybrid, that is being
released as an ornamental, dooryard grape.

Stop 5

Irrigation pump and system will be demonstrated in a block of 'Alachua', a black
muscadine grape. Pruning and fertilization experiments will also be discussed.

Stop 6

Grape progeny test area, contains seedlings from embryo rescue project.

Stop 7

Anthracnose resistance and Pierce's disease. Bunch grape progeny that were
selected for anthracnose resistance in a greenhouse screening test and a field test
of induced resistance to Pierce's disease will be discussed.


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