INSTITUTE OF FOOD AND
UNIVERSITY OF FLORIDA
UNIVERSITY OF 0LORIA
A Vegetable Crops Extension Publication
Vegetable Crops Department 1253 Fifield Hall* Gainesville,FL 32611 Telephone 392-2134
September 13, 1991
S. ) Contents
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
HII. COMMERCIAL VEGETABLES
A. USDA Tomato Size Standards Revision.
B. When LB/A Does Not Equal Pounds Per Acre.
C. Carrot Production in Florida (Daucus carrots .
D. Florida Tomato Institute '91.
E. Bravo 720 Did Not Injure Watermelon Fruit in 1991
III. A. Sweet Corn Cultivar Sulfonyl-Urea Herbicide
IV. VEGETABLE GARDENING
'. A. National Junior Horticultural Association to
Convene in Florida in October.
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
F purpose of providing information and does not necessarily
constitute a recommendation of the product
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, age, handicap or national origin.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA,
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I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
October 25-29, 1991. National
Junior Horticulture Association
Convention. Altamonte Springs. (Contact
Bob Renner, Marion Co. Extension Agent).
October 29-31, 1991. Florida State
Horticultural Society (FSHS). 104th
Anniversary, Doral Ocean Beach Resort,
Miami Beach, FL.
March 5-6, 1992. Postharvest
Horticulture Institute. University Centre
Hotel, Gainesville. (Contact Steve
March 9-12, 1992. Harvest and
Postharvest Handling of Horticultural
Crops. Tour of Central and South Florida.
(Contact Steve Sargent).
March 15-19, 1992. Second
International Symposium on Specialty and
Exotic Vegetable Crops. Miami (contact
II. COMMERCIAL VEGETABLES
A. USDA Tomato Size
Beginning this fall packing season
(October 1, 1991), revised size standards
will be implemented for fresh market
tomatoes. Thus, for the first time since
the 1981-82 season, size standards
regulated by the Marketing Policy of the
Florida Tomato Committee (FTC) will be
identical to the USDA Grade Standards.
This was made possible by a compromise in
the size standards which will now permit a
1/32 inch overlap between sizes. From the
1982-83 season until last year the FTC
permitted a 2/32-inch overlap between
sizes, while the federal standard permitted
no overlap between the sizes. For this
reason tomatoes packed in the FTC
regulated districts had to designate sizes as
6x7, 6x6 and 5x6 and Larger. With the
new standards, Florida packer/shippers will
use the conventional size designations of
medium, large and extra large.
The reason for this compromise was
based, in part, on the sizing study we
performed during the 1987-88 season in
cooperation with the FTC and Florida
Dept. ofAgric. & Cons. Services, Inspection
Division (Sargent, et al., 1991.
Performance of Perforated Belt Sizers as
Affected by Size Standards for Fresh
Market Tomatoes). In this study we found
that Florida packers could easily meet size
standards with a compromise overlap of
The revised USDA size standards
are as follows:
Effective October 1, 1991 the US Standards
for grades of fresh tomatoes will:
-Require that the size of the tomatoes in
any standard shipping container be
specified and marked on the container
*Establish 4 mandatory size designations
(small, medium, large, and extra large),
each with a 1/32-inch overlap);
-Require that only one of the 4 sizes be
included in and be marked on the
*Eliminate the commingling of different
sizes within a container
TOMATO SIZE CLASSIFICATIONS
Min. Diameter Max Diameter
*Small 2 4/32 2 9/32
Medium 2 8/32 2 17/32
Large 2 16/32 2 25/32
Extra Large 2 24/32
*Small size not permitted in FTC regulated
(Sargent, Vegetarian 91-09)
B. When LB/A Does Not
Equal Pounds Per Acre.
The soil test report form is often
one of the most misunderstood and abused
reports we have. The values (numbers)
printed on these forms can easily be
misused if the reader does not understand
the meaning of the numbers. When this
happens, fertilizer programs can be in
The common problem we see has to
do with assuming that the numbers
represent the actual amount of nutrients
available to the crop as if the laboratory
analysis was conducted on a hydroponic
solution. Analyzed nutrients might equal
available nutrients in hydroponics but not
in soils, even in our sandy soils.
The values on the soil report are an
index of the available nutrients and the
index must be accompanied by its
interpretation e.g. Low, Medium, High. If
the soil test procedure is calibrated with
field research, then the index will be
accompanied by a fertilizer
recommendation. In other words, the
index provides information on the portion
of the nutrient needs that can be supplied
from the soil, but the index value does not
tell us the exact amount.
Too many times we see individuals
using the index value in arithmetic
equations to derive a fertilizer amount.
The scenario goes something like this:
The soil report (double acid) says
100 pounds per acre of potassium
(K20) in the sample. Note:
sometimes the report is expressed
as parts per million (ppm) which is
doubled to get pounds per acre. For
example the report says 50 ppm
which would be 100 pounds per
acre. The doubling conversion
factor comes from the rough rule of
thumb that there are 2 million
pounds of soil in an acre furrow
slice. This conversion factor is so
general as to make it worthless for
the purpose above. Anyway, back to
the arithmetic user. In this
scenario the person then takes crop
nutrient removal values (or some
other value) and subtracts the soil
test index to get the fertilizer
amount. For example, some
published tables of crop nutrient
removal values say that tomatoes
remove 300 pounds of K20 per acre.
Therefore, 300 minus 100 (from the
soil test report) equals 200 pounds
of K20 to recommend. Right?
Wrong! Actually, the index value of
50 ppm K20 (42 ppmK) should be
interpreted as medium and receive
only 100 pounds of K2O per acre.
See Special Series SS-SOS-907
(Notes in Soil Science 38).
From the above, we can see that a wrong
use of the soil test index values potentially
results in overfertilization. Remember,
that Florida soils are not hydroponics. A
well calibrated soil test can help determine
amounts of fertilizer ..... as long as the soil
test is not misinterpreted.
(Hochmuth Vegetarian 91-09)
C. Carrot Production in
Florida (Daucus carrots .
Florida harvested about 7,900 acres
of carrots in 1989-90 with an average yield
of 100 cwt/A. Fresh market carrots
accounted for 82% of the production.
Carrot plantings begin in July and continue
at intervals through February. Harvest
begins in early October with mini carrots
from Everglades muck and ends the middle
of June in the Zellwood muck area.
Florida's carrot production is on
muck soils. Where California, Washington,
Texas, and Arizona carrot production is on
mineral soils. Florida has an average yield
around 4.8 tons/A while Texas has 9 and
California has 21.5. Culls account for
greater losses in Florida than other
production areas. Florida losses from 10 to
45% with an estimated average of 23% of
its carrot production to various types of
culls. Yields of 34 tons/A have been
achieved in Florida in small experimental
plots when planted during October.
October has been found to be the optimum
month to plant for higher yields.
The major plant disease in carrot
production in Florida is Alternaria blight
(Alternaria dauci). Using tolerant varieties
along with applications of Bravo, Tri-basic
copper, and Du-ter are helpful in its
control. Other diseases include Cercospora
leaf spot and bacterial blights.
In sandy soil, root-knot and sting
nematodes have to be controlled. At
present, only Vydate L is available. Other
insects attacking carrots are wire worms,
cut worms, and leaf miners when the
carrots are young.
Weeds are usually controlled by use
of herbicides such as Lorox, Roundup,
paraquat, and Fusilade 2000. Mineral
spirits have been used, but cost and timing
are critical to a quality crop.
(White, Vegetarian 91-09)
D. Florida Tomato Institute
On September 4, 1991, the Florida
Tomato Institute convened it's annual
meeting at the Ritz Carlton in Naples,
Florida. Over 350 people were in
attendance representing seven states and
two countries. The morning session
concentrated on new developments
concerning the sweetpotato whitefly and
the associated geminivirus.
Jane Polston spoke on insect
transmitted viruses in Florida and
presented data from a virus survey
conducted in spring of 1991. This data
indicated that while the Florida Tomato
Geminivirus (FTGV) was found to be the
prevalent virus in symptomatic plants, 43%
of the samples tested had more than one
virus associated with those visual
Bob McGovern spoke on alternate
hosts of FTGV. McGovern indicated
preliminary evidence suggests certain
plants may be alternate hosts of the virus:
Hairy spurge (Chamaesyce hirta (L.)
Millsp.), Spurge (Chamaesyce hypericifolia
(L.) Millsp.), Sesbania sp., Water primrose
(Lidwigia erecta (L.) Hara. & (Lidwigia
decurrens Walt.), common bean (Phaseolus
vulgaris (L.)), Tomatillo (Physalis ixocarpa
Brot.), and Tropical soda apple (Solanum
Phil Stansly concentrated on
management strategies for the sweetpotato
whitefly, touching on insecticide resistance,
spray materials, application technologies,
and field sanitation. His data exhibits a
volume of information on spray trials
conducted throughout the past year.
Charlie Vavrina presented
information on the "new" detergent spray
technology from the perspective of foliar
injury and plant dry matter accumulation.
While efficacious in controlling the
whitefly, detergents may be reducing plant
dry matter accumulation. The
ramifications of this weight loss are being
Lance Osborne addressed the
possibilities of biological control of
sweetpotato whitefly, presenting a nice
treatise on this specific subject. A fungal
pathogen of the whitefly shows some
promise and is presently under
investigation by U of F and W. R. Grace in
a cooperative agreement.
The afternoon session presented
information of a more diverse nature
touching on tomato transplant
conditioning, bacterial spot of tomatoes,
Fusarium crown rot of tomatoes, predicting
tomato yield loss to nematodes,
developments in weed control, tissue
testing, and packing line efficiency.
All of these subjects and more are
presented in the Proceedings of the Florida
Tomato Institute 1991. A 178 page book of
the latest developments in the disciplines
at work in the tomato industry. As usual
the appendices contain the full compliment
of Florida Extension recommendations on
varieties, fertilizer management, weed
control, insect control, disease control, and
nematode control. Proceedings of the 1991
Tomato Institute are available for sale
through the SWFREC, P.O. Drawer 5127,
Immokalee, FL 33934 (attention C.
Vavrina) at a cost of $5.00 plus $1.50
postage and handling ($6.50) total).
Checks for the Proceedings should be
made payable to SW Florida Vegetable
Committee. Allow 3 weeks for delivery.
(Vavrina, Vegetarian 91-09)
E. Bravo 720 Did Not Injure
Watermelon Fruit in 1991 Trial.
Applications of the Bravo 720
formulation of chlorothalonil (ISK Biotech
Corporation, Mentor, OH 44061-8000)
have been reported to cause injury, similar
to sunburn, on the surface of watermelon
fruit. When the injury occurred, it was
usually associated with applications of the
fungicide to watermelon crops nearing
maturity with sparse vine cover during
periods of intense sunlight and high
Based on information available prior
to the 1991 watermelon season, ISK
Biotech issued an information bulletin (1)
to growers which provided the following
guidelines for Bravo 720 use on
watermelons: (a) do not tank mix with any
other product, (b) do not apply within 21
days of first harvest if periods of intense
sunlight and high temperatures are
expected, and (c) do not apply within 21
days of first harvest when vines do not
provide shading of fruits, or if vines are
stressed due to drought.
The objective of this experiment
was to determine the effects of weekly
applications of Bravo 720, with applications
omitted at designated periods before
anticipated first harvest date, on four
watermelon varieties that differed in rind
color and pattern.
'Crimson Sweet', 'Royal Jubilee',
'Sangria', and 'Southern Belle' watermelons
were direct-seeded on 11 March in holes
punched in the polyethylene mulch at 3 ft.
in-row spacing at GCREC, Bradenton. The
30 ft. long plots had 10 plants and were
replicated four times in a randomized,
complete block design. Weed control in
row middles was by cultivation and
applications of paraquat.
Bravo 720 treatments were applied
weekly at 3 pt/100 gal/acre according to
the following schedule:
Time of Last Application
Days Before (-) or
After (+) First Harvest
No detectable injury on watermelon
fruit was observed that could be associated
with Bravo 720 applications. The injury
had been associated previously with high
light intensity and temperatures in the
period immediately proceeding harvest.
These conditions did not occur in this trial
because of overcast skies and frequent
showers during the last two weeks of May
and in early June. Sparse vine cover, also
associated with Bravo 720 injury, did not
occur in this trial except in plots that had
not received Bravo 720 applications for 23
and 30 days before first harvest.
Early and total yields, average fruit
weight, and soluble solids varied among the
four varieties included in this trial. This
was to be expected since they were
representative of different watermelon
types. The incidence of hollowheart,
however, did not vary among varieties.
'Southern Belle' was more susceptible to
gummy stem blight than the other three
The number of Bravo 720
applications did not affect early and total
yield, average fruit weight, soluble solids
concentration, and incidence of
hollowheart. On the other hand, the
incidence of gummy stem blight was
significantly greater in those plots that
received five or six Bravo 720 applications
compared to those that received seven,
eight, or ten Bravo 720 applications.
The surface temperature of
watermelon fruit greatly exceeded air
temperature regardless of whether the
fruit was in the shade or sun, and
temperature of fruit in the sun exceeded
that of shaded melons. Temperature of
shaded fruit was similar regardless of
variety, whereas considerable difference in
temperature among varieties was recorded
for fruit in the sun. Temperature had no
apparent relationship to rind color or
pattern. The rind temperatures from
darkest to lightest rinds were 'Southern
Belle', 103.8; 'Sangria', 108.4; 'Crimson
Sweet', 110.3; and 'Royal Jubilee', 104.7F.
Therefore, the lowest rind temperature
occurred in the darkest and lightest
A relationship between frequency of
Bravo 720 applications and the occurrence
of fruit injury was not established in this
experiment. If previous observations
relating the injury to high light intensity
and high temperature are correct, the
results might be explained by the high
frequency of overcast skies during the two
week period before harvest. Another
possibility is that the observed fruit injury
was related to some factor other than
application of Bravo 720.
(D. N. Maynard and J. P. Jones,
HI. PESTICIDE UPDATE
A. Sweet Corn Cultivar -
Sulfonyl-Urea Herbicide Interactions.
This past year 2 sulfonyl urea class
herbicides have been labelled on corn. The
herbicides are Accent (Dupont) and Beacon
(Ciba-Geigy). We have received several
calls on their use in sweet corn in Florida.
At the present time neither
herbicide is labelled for use on sweet corn
in Florida. If either was labelled for use
with the present labelled rates, I could not
recommend their use on sweet corn in the
For the past 4 years, we have run 6
replicated trials in Florida on a total of 24
cultivars. Only 2 of the 24 cultivars were
classed as completely tolerant (no yield loss
- in any trial) to the application of these
herbicides over the top of 10 inch high
plants. Thirteen of the 24 cultivars had
slight to 30% yield reduction in at least one
or more of the trials. Eight cultivars of the
24, or 1/3 of the total, had unacceptable
yield loss due to application of the
herbicide(s). Most of these cultivars had 0
to 30% of the expected yield.
When a systemic soil insecticide,
such as Counter was used at planting,
almost all cultivars showed a reduction in
yield due to the herbicide application.
When a non-systemic soil insecticide, such
as Lorsban was used, the reduction in yield
due to herbicide was not as pronounced.
If the application of the herbicides
were made as a post-directed treatment to
cultivars that did not have any granular
soil insecticides applied at planting, the
safety of the herbicides increased
substantially. Only one breeding line
showed unacceptable (0%) yield. Over half
(14 of 24) cultivars showed complete
tolerance, but 9 of the 24 still displayed
phytotoxicity and some yield reduction in
at least one trial.
Due to these findings, I can not
recommend that these herbicides be
labelled or used on sweet corn in Florida.
Another problem is rotational limitations
behind the application of these herbicides.
Accent has a 120 day plant back for
vegetables and Beacon has an 18 month
Soil dissipation studies and more
work on safety must be done before these
herbicides should be used in Florida on
(Stall, Vegetarian 91-09)
IV. VEGETABLE GARDENING
A. National Junior
Horticultural Association to Convene
in Florida in October.
Approximately 400 youth and adult
leaders from 35 states will gather in
Altamonte Springs at the Hilton Hotel for
the 57th annual convention of the National
Junior Horticultural Association (NJHA),
Oct. 25-29, 1991.
The NJHA is the only youth
organization in America totally dedicated to
the promotion of horticulture. The
majority of its membership are 4 H'ers and
FFA'ers who are routinely involved in
projects and activities related to the
production, marketing, or use of such
horticultural products as fruits, vegetables,
turf, flowers and woody ornamental. The
association provides a mechanism for these
individuals to compete and interact on a
national level in a variety of activities and
The NJHA convention brings all of
the state winners and top achievers
together for final competition and for
receiving awards and recognition. It is held
in a different state annually. Florida has
hosted two previous such conventions, one
in 1962 (Miami Beach), and the other in
1971 (Miami Beach).
The present convention is being
arranged by a Florida host committee of
Cooperative Extension workers under the
joint leadership of David Dinkins, Nassau
County Extension Agent, and Bob Renner,
Marion County Extension agent.
The program is still under
development but here is the general
outline of main events being drafted.
Friday, Oct. 25.
P.M. Arrive, register, and check-in
P.M. Welcome banquet.
Saturday, Oct. 26.
A.M. Horticultural identification and
P.M. Horticultural Demonstrations,
public speaking, and special projects
Sunday, Oct. 27.
AM. Horticulture workshops.
P.M. Tour Cypress Gardens.
Monday, Oct. 28.
All day Tour Epicot Center
P.M. Awards and recognition
Tuesday, Oct. 29.
AM. Check-out and depart.
Florida will be represented by a host
of adults working on various components of
the convention, and by an official
delegation of 4 H'ers. These 4-H team
members are our state winners in the 4H
Horticulture Demonstrations: Allison
Clarke and Jan Graves from Duval County,
and in the 4H Horticulture Identification
and Judging Contest, from Marion County
(Amy Williams, Ben Yawn, Tammy
Obermark, and Amanda Clark).
Expenses for the aforementioned
4 H'ers are being defrayed by the sponsors
of our state 4H horticulture program,
which includes the Florida Fruit and
Vegetable Association, Nye Brands, and the
Florida Department of Agriculture.
Other youth in Florida (thru age 18)
may also attend the convention at their
own expense. They can participate in as
many of the activities as they qualify for.
We anticipate and welcome a large number
from Florida (4H, FFA, and other) in this
All of us connected with this
convention and 4H in Florida wish to
recognize with appreciation the support
provided by the Florida Fruit and
Vegetable Association in hosting this
national group. This important industry
organization is sponsoring most of the cost
of the convention not
covered by registration fees.
The 57th annual convention should
be a good one, and we are looking forward
to seeing many of our horticultural
associates and friends from around the
Anyone wishing to find out how to
register for the convention or to receive
further information should call either: Bob
Renner, (904) 620-3440, or David Dinkins,
(Stephens, Vegetarian 91-09)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. S. M. Olson
Mr. J. M. Stephens
Dr. G. J. Hochmuth
Dr. S. A. Sargent
Dr. C. S. Vavrina
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. J. M. White