INSTITUTE OF FOOD AND FLORIDA
AGRICULTURAL SCIENCES COOPERATIVE
IFAS U UNIVERSITY OF FLORIOA EXTENSION SERVICE
A Vegetable Crops Extension Publication
L Vegcablc Crops Department 1255 HSPP Gainesville, FL 32611 Telephione 392-2134
Vegetarian 89-11 November 15, 1989
SI. NOTES OF INTEREST
(. ^' .. ,' B. New Publications.
II. COMMERCIAL VEGETABLES
A. New Tomato Virus Outbreak in Southwest Florida.
B. Tomato Transplants & Gemini Virus.
C. Results of Muskmelon Nitrogen Studies.
III. PESTICIDE UPDATE
A. Section 18 for Diquat in Tomato and Pepper Row
B. Diquat 24C Label for Burndown of Tomato Vines.
ST C. Dacthal W-75 Supplemental Labeling for Brassica Leafy
4 ..:.'>,: D. Supplemental Label for Aerial Application of Gramoxone
IV. VEGETABLE GARDENING
A A. Florida's Largest Vegetables (record update).
Note: Anyone is free to use the information in this newsletter.
Whenever possible, please give credit to the authors. The purpose of
trade names in this publication is solely for the purpose of providing
information and does not necessarily constitute a recommendation of
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.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA, IFAS. UNIVERSITY OF
FLORIDA, U. S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING
I. NOTES OF INTEREST
Jan. 13, 1990. Suwannee Valley
Vegetable and Greenhouse Morning Ses-
sion: Field Vegetable; Afternoon Session:
Jan. 24, 1990. Florida Sweet Corn
Institute. Florida Fruit and Vegetable
Assn. Conference Room. Orlando. 9:45 -
Jan. 30, 1990. Florida Watermelon
Institute. Marion County Extension
Office. Ocala. 1:00 5:00 pm.
Feb. 14-15, 1990. Ninth Annual
FSGSA-IFAS Seed Seminar 1990. Holiday
Inn West, Gainesville, FL.
B. New Publications.
Maynard, D. N. Annual Rhubarb
Production. Fall-Spring 1988-89. GCREC
Bradenton Research Rpt. BRA1989-18.
Howe, T. K and W. E. Waters.
Evaluation of Ornamental Cabbage and
Kale as Bedding Plants During Two
Winter Seasons. GCREC Bradenton
Research Rpt. BRA1989-10.
Albregts, E. E., C. K. Chandler, and
C. M. Howard. Strawberry Variety Trials
1989. AREC Dover Research Rpt. DOV-
Chandler, C. K, C. M. Howard, and
E. E. Albregts. Research Highlights from
the Agricultural Research & Education
Center at Dover. AREC Dover Research
Maynard, D. N. Seedless
Watermelon Variety Evaluation Spring
1989. GCREC Bradenton Research Rpt.
Maynard, D. N. Plum Tomato
Variety Evaluation Spring 1989. GCREC
Bradenton Research Rpt. BRA1989-15.
Woltz, S. S. and J. P. Jones.
Fusarium Wilt (Race 3) of 'Sunny' Tomato
in Florida Peat-Vermiculite Mix with
Lime and Micronutrients Varied. GCREC
Bradenton Research Rpt. BRA1989-14.
Maynard, D. N.
Evaluations Fall 1988
& Spring 1989.
Maynard, D. N. Icebox Water-
melon Variety Evaluation Spring 1989.
GCREC Bradenton Research Rpt.
Howe, T. K, J. W. Scott, and W. E.
Waters. Tomato Variety Trial Results for
Spring 1989. GCREC Bradenton GCREC
Research Report BRA1989-17.
Vavrina, C. S. and K Armbrester.
Tomato Variety Trial Immokalee Site,
Spring 1989. SWFREC Research Rpt.
II. COMMERCIAL VEGETABLES
A. New Tomato Virus Outbreak
in Southwest Florida.
Late on Friday, September 8, a
series of tomato samples were submitted
to the Florida Extension Plant Disease
Clinic (FEPDC). These samples
originated from Collier County from
scouts employed by Glades Crop Care, Inc.
One plant exhibited a bright yellow
mosaic symptom that is typical of
symptoms induced by the 'gemini' viruses.
Appropriate sample processing followed
and resulted in the diagnosis of an
unspecified 'gemini' virus affecting these
The 'gemini' viruses represent a
fairly new group of viruses. Florida
tomato growers are already familiar with
the more common representative of this
group in the State--pseudo curly top virus,
which is a minor problem during fall
production periods. The 'gemini' viruses
possess single-stranded, circular DNA and
exist as paired particles in the plant.
This group of viruses is vectored by either
whiteflies or leafhoppers and is typically
neither seed transmitted nor mechanically
transmitted at high frequencies.
Symptoms on infected plants seem
to reflect two distinct viruses. The most
obvious case was a bright, canary yellow
mosaic accompanied by leaf distortion and
puckering. Plant stunting seemed to be
correlated with early infection. This
syndrome was rare in the field and
represented less than 0.5% of plants. The
second disease syndrome was far more
extensive in the field. Some early
planted fields in the Naples area exhi-
bited a 98-100% plant infection in the
field across 14-20 acre blocks. Affected
plants developed a stunted appearance
accompanied by a downward arching of
petioles. Leaflets exhibited a mottled
appearance with common interveinal
chlorosis, as if the plant was minor
element deficient. Leaflets would exhibit
curling (upward or downward), distortion,
and in some plants an obvious vein
banding. Severity of symptoms seemed to
correlate with earliness of infection. No
fruit symptoms, flower or fruit abortion
has been observed to date.
In the two weeks that followed, a
number of tomato samples were received
from commercial and research fields in
the Collier/Lee, Hillsborough/Manatee,
and Gadsden tomato production areas.
Approximately half of the two dozen
samples received were confirmed to be
infected with a 'gemini' virus. On Sep-
tember 27-29, a field survey was under-
taken by G. W. Simone in the Collier and
Manatee county areas. Approximately
four dozen samples were collected from 12
different growers in the two county tour.
samples were processed,
diagnostic results are
Tomato samples processed for gemini virus infection from Sept. 8 Oct. 7, 1989
Gemini Virus Samples1
No. of Virus Virus
County No. of growers samples present absent
Collier 10 44 37 7
Gadsden 3 3 0 3
Hillsborough 2 2 2 0
Lee 1 1 1 0
Manatee 7 11 9 2
'Positive samples were obtained from 11 cultivars or breeding lines.
2ome negative responses were due to inadequately submitted samples
vented appropriate processing.
Field survey results indicated a
wide distribution of this 'gemini' virus
complex in the Collier/Lee and
Hillsborough/Manatee production area.
Growers that planted at the end of July
through the first two weeks of August
had fields with almost uniform infection.
Successive planted fields exhibited 5-15%
infection after being in the fields for 6
weeks. The suspected vector is the sweet
potato whitefly (Bremisia tabaci) which is
still prevalent in all tomato fields
examined. No weeds, sampled to date,
have been found positive for this virus.
Until the identity of the 'gemini' virus(s)
is known, specific information on the
vector, biology of the virus in the vector
and host plant, weed hosts, useful control
measures, and potential yield impact in
Florida cannot be defined.
Sample processing to date has
relied entirely upon the search for
nuclear inclusions produced by the virus
in the parenchyma cells associated with
the vascular tissue. These inclusions can
be observed after suitable staining with a
selective nucleic acid stain (Azure A) in
thin sections cut through leaflet or petiole
veins and examined under 1600x magnifi-
cation. To process tomato samples for
both the normally observed viruses in
Florida and the 'gemini' group, average
preparation and examination time is 45-
60 minutes per sample.
The Plant Pathology Department
in IFAS is reacting to this potentially
damaging new disease as follows:
1. Samples are continuing to be pro-
cessed in the FEPDC to further
document disease distribution
2. Samples of symptomatic plant
material have been sent to Dr.
Judith Brown at the University of
Arizona for identification of the
virus(s) present in the southwest
tomato production area. Dr. Brown
is one of the few researchers in
the United States that possesses
the diagnostic technology to
distinguish among the 'gemini'
viruses. These samples were
forwarded to Arizona on October 4.
3. Dr. Ernest Hiebert (IFAS) has veri-
fied the 'gemini' virus diagnosis
made through the use of plant
virus inclusions by testing plant
extracts against an antiserum to
another 'gemini' virus--bean golden
4. The Plant Pathology Department
invited Dr. Brown to Florida for
consultation on this virus problem.
5. Additional field survey work will be
conducted for both the virus inci-
dence and possible weed reservoir
hosts once the identity of this
virus is known.
6. Plants are ready for necessary virus
transmission studies by grafting
and mechanical transmission once
the virus is identified.
7. Further information will be re-
leased concerning the virus disease
cycle, etc. once identity of the
specific 'gemini' virus is revealed.
(Simone, Extension Plant Pathologist,
B. Tomato Transplants & Gemi-
A major concern for tomato
growers statewide this fall has been the
whitefly transmitted Gemini virus. A
concern has been whether or not the vi-
rus could be shipped in on the transplant.
To date, there are no reports of trans-
plants being rejected because of obvious
virus symptoms. However, as the source
of inoculum continues to grow, symptoms
may be seen on younger and younger
plantings, implying transplant involve-
The sweet potato whitefly has a
range that extends from 30S to 30 N in
latitude (slightly north of St. Augustine,
FL). In this range they can freely repro-
duce and overwinter. If a plant contain-
ing white fly pupae or adults is shipped to
Michigan, for example, these life stages
can develop and produce successive
generations during the summer. Should
either of these shipped stages contain
virus, the virus may possibly spread.
In spring 1990, for vegetable
transplants shipped out of state, DPI will
enforce a July 1987 ruling designed to
address whitefly infestations in bedding
crops. This rule simply states that if 20%
of the plants in the crop have 20% of the
leaves infested with 5 or more whiteflies
or pupae, the crop will not be certified.
This level of incidence indicates inade-
quate whitefly control and will justify
regulatory action. The crop can be
certified and shipped with proper clean-
up in terms of reduced whitefly numbers.
The state of Florida does not regulate
transplant traffic within its boundaries.
Producers of spring vegetable
transplants should be highly concerned
with sanitation. Not just within the plant
house, but around the plant house and in
fields adjacent to the plant house. At the
present time we are not sure which weeds
may be harboring a ready source of
Gemini virus. However, the fall tomato
crop or its residue can provide all the
inoculum needed to infect the spring
transplant crop for northern markets.
(Vavrina, Vegetarian 89-11)
ults of Muskmelon
During 1986-89, Ed Hanlon, Bob
Hochmuth and I have conducted N stu-
dies with polyethylene-mulched muskme-
lons in various cultural systems. Four
studies were conducted testing rates of N
from zero to 240 lb. per acre. Studies
were conducted in Gainesville, Osteen,
and Live Oak, Florida. Overhead sprink-
ler, subsurface, and drip irrigation was
used at Gainesville, Osteen, and Live Oak,
respectively. Results showed that N crop
nutrient requirements were about 120 to
140 lb. per acre calculated on basis of 5-
foot bed centers (8700 linear bed feet of
crop). Substantially less N was needed in
situations where mulch was used on soils
with organic matter greater than 2.0%.
Muskmelon leaf-nitrogen critical concen-
trations were 4% at early fruit set.
(Hochmuth, Vegetarian 89-11)
III. PESTICIDE UPDATE
A. Section 18 for Diquat in
Tomato and Pepper Row Middles.
The U.S. Environmental Protection
Agency (E.P.A.), under the provisions of
section 18 of FIFRA, has issued a specific
exemption for use of Diquat to control
nightshade and parthenium on tomatoes
and green peppers.
A maximum of 2 ground applica-
tions at a rate of 0.5 lb. a.i. per acre may
be made per season. A thirty (30) day
PHI will be observed. The exemption
expires August 31, 1990. All instructions
on the label must be followed.
B. Diquat 24C Label for Burn-
down of Tomato Vines.
Diquat has received a special local
needs (24C) label for use for burndown of
tomato vines after final harvest.
The label states application of 1.5
pints of Diquot per acre in 60 to 120 gal-
lons of water per acre. Add 16-32 ounces
of Valent X-77 spreader per 100 gallons of
spray mix. Thorough coverage of tomato
vines is required to insure maximum
To help facilitate removal of Sweet
Potato Whitefly, burn tomato vines with
propane burners as soon as possible after
the vines have dried down sufficiently.
C. Dacthal W-75 Supplemental
Labeling for Brassica Leafy Vegetable
Fermenta ASC has added the Bras-
sica leafy vegetables to the Dacthal W-75
Dacthal W-75 may now be applied
at 6-14 lb. (product) at seeding or trans-
planting to the Brassica Group. This
group includes broccoli, Chinese broccoli,
broccoli raab rapinii), Brussels sprouts,
cabbage, Chinese cabbage (bok choy,
Napa), Chinese mustard cabbage (gai
choy), cauliflower, collards, kale, kohlrabi,
mustard greens, and rape greens.
The Supplemental Labeling must
be in the possession of the user at the
time of pesticide application.
D. Supplemental Label for
Aerial Application of Gramoxone Super.
ICI Americas has added an aerial
application label to the preplant or pre-
emergence treatment for lettuce, melons,
peppers, and tomatoes.
Gramoxone Super should be ap-
plied at 2 to 5 pints per acre before or
after planting but before crop emergence.
Aerial applications should be made in a
minimum of five (5) gallons of water per
acre. A nonionic surfactant should always
The supplemental labelling must be
in the possession of the user at the time
IV. VEGETABLE GARDENING
A. Florida's Largest Vegetables
As most of you know we now have
a procedure to follow for recording our
state's largest vegetables. That procedure
depends on the assistance of Extension
agents in verifying record-size veggies and
transmitting the pertinent vital statistics
to me for entry into the computer file.
Since initiating the formal
procedure in February of this year, agents
have submitted 5 new records canta-
loupe, cucumber (weight and length),
watermelon, pumpkin, and kohlrabi. A
large head of cabbage was also weighed in,
but it did not surpass the old record. I
say "old" record, for I have been keeping
tabs on large vegetables grown in the
state for several years in an accurate but
The following are the current
standings as of November 1, 1989.
(Stall, Vegetarian 89-11)
Table 1. Current Florida record-size vegetables, 1 November 1989.
Vegetable Size Grower Location Date Recorded
19 lb. 1 oz.
16 lb. 8 oz.
19 5/16 in.
3 lb. 14 oz.
4 lb. 15 oz.
17' 6 1/4"
20 lb. 0 oz.
W. Palm Beach
W. Palm Beach
W. Palm Beach
W. Palm Beach
Agents may order official record
keeping forms from Jim Stephens,
Gainesville. These forms give instructions
on how to measure, verify, and report the
achievement to me.
(Stephens, Vegetarian 89-11)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. G. J. Hochmuth
Dr. S. M. Olson
Dr. W. M. Stall
Dr. C. S. Vavrina
Dr. D. D. Gull
Dr. D. N. Maynard
Dr. S. A. Sargent 7
d 1y t ens
professor (E 'tor)
Dr. J. M. White