INSTITUTE OF FOOD AND
UNIVERSITY OF FLORIDA
A Vegetable Crops Extension Publication
Vegetable Crops Department 1255 H
April 14, 1989
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
B. New Publications.
II. COMMERCIAL VEGETABLES
A Pollination of Cucurbits: Cantaloupe, Cucumber, Squash
B. Waxing Vegetables.
C. Leaf Sampling for Tissue Analyses.
S (! D. Potential Spring Pest Problems.
S1 UI. PESTICIDE UPDATE
A. Watermelon Promotion Program.
IV. VEGETABLE GARDENING
A. 1989 4-H Horticulture Institute.
SNote: 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.
rnnPFRATIVF FYTFNIqlN WnRic IN ArRIPI II Ti iR AMn i-lnMF Fr'mNMi'M STATE OF FLORIDA IFAS UNIVERSITY OF
I. NOTES OF INTEREST
May 18, 1989. Vegetable Field
Day, Gulf Coast Research and Education
Center, Bradenton (Contact Don
24-28, 1989. State 4-H
Events 4-H Congress.
(Contact Jim Stephens).
July 30 Aug. 4, 1989. ASHS
Convention, Tulsa, OK.
August 23-25, 1989. Florida
Master Gardener Continued Training
Conference. Reitz Union, University of
Florida, Gainesville. (Contact Kathleen
Ruppert, Ornamental Horticulture).
B. New Publications.
Production of Miniature Vegetables
in Florida by D. N. Maynard, Fla. Coop.
Ext. Serv. Veg. Crops Fact Sheet 36.
II. COMMERCIAL VEGETABLES
A. Pollination of Cucurbits:
Cantaloupe, Cucumber, Squash and
Cucurbit plants have separate male
staminatee) and female pistillatee) flowers.
Male flowers appear on the plants several
days before female flowers. The female
flower is easily recognized by the presence
of a miniature fruit below the flower
petals. Pollen from the male flower must
be transferred to the female flower for
pollination and subsequent fruit
development to occur.
Cucurbit flowers open shortly after
sunrise and remain open until late
afternoon. Accordingly, each flower is
open for only a few hours. The period of
maximum honey bee the most common
and effective pollinator of cucurbits -
activity closely coincides with the period
when the flower is open. Honey bee
visitation begins an hour or two after
sunrise and continues until mid-afternoon.
If temperatures are very warm, bee
activity may decline about noon.
Research on cantaloupe pollination
conducted in California showed that bee
visitations increased until 10 a.m. and
then declined until 3 p.m. when activity
In Florida, research on watermelon
at the Central Florida Research and
Education Center-Leesburg showed that
the number of bee visitations was more
important than the length of time that
each bee stayed on the flower. Well-
shaped, fully expanded fruit occurred
following eight bee visitations to a flower.
Fruit set was significantly reduced when
only four or two bee visitations were
Therefore it appears to be
necessary to have a sufficiently high
honey bee population to insure that each
flower is visited at least eight times. How
does this translate into hives per acre?
Recommendations from various sources
range from two hives per acre to one hive
per five acres. Under most conditions,
however, one strong hive per two acres
should result in sufficient bee activity to
effect needed pollination. Hives should
be spaced around the perimeter of large
fields to provide distribution of bees over
the entire field. To maintain the health
and activity of the bee colonies, pesticide
applications to the crop should be made
in the late afternoon or early evening
when bees are not present in the field.
(Maynard, Vegetarian 89-04)
B. Waxing Vegetables.
The primary reason for waxing
vegetables is to improve their lustre and
to control shriveling through a better
retention of their natural moisture. To a
lesser extent, wax coatings also act as
lubricants to reduce surface scaring and
chaffing. Commercial formulations of wax
mixtures sometimes contain coloring
materials which adds to the appearance of
the vegetable, sprout inhibitors (potatoes),
and fungicides which aid in preserving
market quality. With the exception of
paraffin-dipped rutabagas and excessively
waxed cucumbers, the food grade waxes
applied to vegetables is applied so thin
that it is not necessary to remove it
before the vegetable is cooked or eaten
Vegetables that are most commonly
waxed are cucumber, tomato, pepper,
summer squash, and to a much lesser
extent, potato, sweet potato, eggplant, and
Recently, we have received several
calls concerning the safety of ingesting
these food-grade waxes applied to Florida
vegetables. We have contacted several
suppliers of vegetable waxes concerning
wax ingredients. All suppliers contacted
said their vegetable waxes contain no
fungicides (fruit waxes may), and that all
materials used are EPA approved.
However, a fungicide (orthophenylphenol)
is used as a wax preserver but not for the
vegetable. One wax label reads "FOOD
GRADE TOMATO WAX WITH
FUNGICIDE" with ingredients of food
grade oils, natural wax, emulsifier, natural
coloring and anti-oxidant
(orthophenylphenol). Another label
"CUCUMBER AND PEPPER LUSTR"
contains food grade mineral oil, petroleum
wax, artificial color, and
orthophenylphenol as wax preservative.
Put in proper perspective, the
CUCUMBER & PEPPER LUSTR contains
active ingredient (orthophenylphenol) of
2.5% and one gallon of wax should be
applied to 75,000 lbs. of produce.
The amount ingested per cucumber or
pepper consumed would indeed be
extremely small. Additives to food-grade
waxes applied to vegetables do not pose
any danger to the consumer.
(Gull, Vegetarian 89-04)
Leaf Sampling for Tissue
Leaf-tissue nutrient analysis is a
good tool for monitoring our crop's
nutrient status and for diagnosing
suspected nutrient deficiencies. Just like
soil analysis, the key to good leaf analyses
lies in a quality sample. The published
book values for interpretation of
laboratory analytical results are based on
a certain leaf age or plant part. This
differs somewhat depending on the source
of interpretation information and on crop.
Another consideration is for the physical
condition of the leaves and whether or
not they are contaminated with foliar
pesticides or foliar fertilizers. The
following are general guidelines that will
help secure a good sample under most
conditions so that the analyses and
interpretations will have meaning.
1. Which leaf? Most critical nutrient
values for vegetables are based on
analysis of the "most recently
matured" whole leaf. "Whole leaf'
would include the leaf blade plus
the petiole. For crops, such as
tomato or potato that have
compound leaves, then "whole leaf'
means the entire leaf including the
main petiole plus the leaflets with
their "petioliules". "Most recently
matured" means that leaf that has
attained near full size. I usually
select the leaf that has nearly lost
its youthful light-green color but
which has not turned a deep dark-
green color. For tomato, this is
usually about the 5th or 6th leaf
from the tip and will be about 6 to
8 inches in length.
2. What about contamination? When
selecting leaves, try to avoid leaves
that have been sprayed with
nutrient-containing pesticides or
foliar fertilizer nutrients. This is
especially true for micronutrient
analyses. Numbers obtained under
these circumstances are largely
meaningless. If only a slight
residue is present, the best way to
remove it is by wiping the leaves
with a cloth soaked in a dilute
mild detergent solution. Soaking
in detergent or acid solutions often
will remove or "extract" nutrients
from the leaf.
3. Diseased leaves? Try to avoid
sampling leaves that are obviously
diseased or decayed. These leaves
will not yield valuable information
and might rot by the time they
reach the laboratory.
4. Handling the sample? Collect
leaves into paper bags that are
well labeled as to crop, location of
crop, date, notes on crop condition,
etc. Transfer samples quickly to
the lab. If samples can not be
taken to the lab immediately, then
it is a good idea to "pre-dry" the
samples in a shaded, dust-free,
well-ventilated area. Once nearly
dry, the samples can be shipped to
5. Trouble-shooting. When
diagnosing suspected nutrient
problems, always try to sample
"good" and "bad" plants from the
field. Comparison of the analytical
results will help in pinpointing a
nutrient problem if it is the
culprit. In addition, it is helpful to
have soil analyses run for at least
pH, if the problem is suspected to
be related to micronutrients.
When soil sampling, avoid the
6. Helpful information. Try to gather
as much additional information as
possible. Ask about the fertilizer
program, rainfall, weather,
irrigation, past field use, etc. Also
never neglect to check for other
problems such as nematodes or
root diseases whose symptoms may
mimic nutritional deficiencies.
7. Summary. Plant tissue analysis is
a good tool to help us maximize
fertilizer management programs.
Like soil analysis it could be a
waste of time if we don't spend
the time to do it right. It all
starts with a good sample.
(Hochmuth, Vegetarian 89-04)
In visiting growers fields recently,
several pest problems have been found.
Ants seem to be more of a problem this
year in watermelons both on and off
plastic. One bare ground field was
virtually destroyed by ants feeding. Most
watermelon plants were showing signs of
thrips damage on the leaves. Prodigous
amounts of thrips, primarily the Western
flower thrips were found in blackberry
blooms around the field.
The Western flower thrips have
also been found in strawberry blooms and
tomato blooms. High populations of
thrips have caused feeding damage on the
strawberry fruit. In tomatoes, we have
been associating a small feeding scar
surrounded by white tissue with the
Western flower thrips but has not been
confirmed until recently. A graduate
student, Victor Salguero, has confirmed
the damage using small cages to confine
various thrips species with tomato blooms.
The damage he is getting from the
Western flower thrips is identical to that
found in the field. The Western flower
thrips, in addition to its feeding damage,
can transmit the tomato spotted wilt
virus to tomatoes, peppers, watermelons,
and other crops.
One other potential problem in
tomatoes this spring is two-spotted spider
mites. They have been found in several
growers' fields. This is the earliest that
they have been found. There are very
few products that are registered and
effective for mite control in tomatoes.
Potential I_~ ___
Growers may want to intensify
their scouting programs to try and keep
severe outbreaks from occurring. The
county extension office should be
contacted if help is needed for
identification or control recommendations.
(Olson, Vegetarian 89-04)
IH. PESTICIDE UPDATE
A. Watermelon Promotion
Press Releases 03/31/89.
Watermelon producers and handlers
approve research and promotion program.
Washington, March 31 Watermelon
producers and handlers have voted to
adopt a federal research and promotion
plan, a U.S. Department of Agriculture
official announced today.
J. Patrick Boyle, administrator of
USDA's Agricultural Marketing Service,
said that in a referendum conducted in
February, a majority of producers (approx.
52 percent) and a majority of handlers
approx. 56 percent) approved the plan.
Those in favor of the plan accounted for
73 percent of the volume of watermelons
grown or handled by those voting in the
The plan meets statutory criteria
for industry approval, according to Boyle.
To pass, the referendum had to be
approved by either two-thirds of those
voting, or a majority of producers and a
majority of handlers accounting for at
least two-thirds of the volume of
watermelons grown or handled by those
voting in the referendum.
Authorized by the Watermelon
Research and Promotion Act of 1985, the
plan also provides for the establishment
of a National Watermelon Board. The 29-
member board will be composed of
producers, handlers and the general
public. Twenty-eight members of the
board will be appointed by the secretary
of agriculture from nominations
originating in the industry; one will be a
public member appointed by the secretary
from outside the industry. Industry
representatives will be divided evenly
between handlers and producers.
The board's responsibilities will
include development and recommendation
of research, promotion, and advertising
projects for approval by the secretary.
The board also will oversee a small
administrative staff managing the
program's daily work. Projects developed
by the board and approved by the
secretary will favor no particular
production region or variety of
watermelon grown in the contiguous 48
The plan allows for the
establishment of projects relating to the
research, promotion, and advertising of
watermelons. Funds to administer the
program will be derived from assessments
on producers and first handlers of
watermelons, Boyle said. The assessment
rate, to be recommended by the board
and fixed by the secretary of agriculture,
can be set at a maximum of two cents per
hundred pounds for producers and two
cents per hundred pounds for handlers.
All producers of five acres or more
and first handlers are required to pay the
assessment. A grower of five or more
acres of watermelons who also handles
watermelons would pay both assessments.
However, producers and handlers who do
not wish to support the program can
obtain a refund upon written request.
(Stall, Vegetarian 89-04)
IV. VEGETABLE GARDENING
1989 4-H Horticulture
The three IFAS horticulture
departments Vegetable Crops, Fruit
Crops, and Ornamental Horticulture are
jointly conducting a plant science-oriented
summer camp experience for 4-H Youth
(ages 10-18). This year, vegetable crops
will be spotlighted. The program focal
point for last year's Institute was fruit
crops, and next year it will feature
ornamentals, all part of the three-year
The 1989 Hort Institute will be
held the week of June 19-23, at 4-H
Camp Ocala located off Highway 19, 5
miles south of Highway 40, 13 miles
north of Umatilla in Lake County. The
60 acre camp is situated on Lake Sellers
in the Ocala National Forest. Enjoyable
lodging, food, meeting, and recreational
facilities are conveniently located in a
serene and relaxed environment.
The camp staff includes the year-
round regulars and the summer program
staff provided through the State 4-H
Department. This staff is composed of
camp managers, caretakers, cooks,
lifeguards, recreation leaders, and first-aid
personnel. We rely on them for the day-
to-day operational procedures which are
essential to smooth, efficient, enjoyable,
safe camping. Fortunately they are used
to working with groups like ours
throughout the summer.
Our Institute staff will have an
operational component and a program
component. Tom Greenwalt (State 4-H
Specialist) heads the operations section,
while it is my turn to head the program
group. Both of us rely heavily on
Kathleen Ruppert and other Institute
committee members composed of IFAS
specialist and county 4-H/horticulture
Key members of Tom's operations
group include Linda Landrum, Volusia
County Hort Agent (registrar); Alice
Ayers, Lake County 4-H Agent (Dean of
Women); and Dan Schrader, Flagler
County Extension Director, (Dean of
Men). Cabin leaders will come from a
group of adult volunteers and older 4-H
members. Our program group includes a
host of speakers, instructors, and
horticulture activity leaders.
Here is a list of the educational
events planned for the 1989 4-H Hort
to the camp.
production area closeby
To be conducted in
afternoon of fun at Wild
Horticultural Judging and
Identification Contest. Horticulture
Demonstrations. Horticultural Exhibits.
Be a TV Personality
Gardening with Leftovers
Keep Our Earth Cool
Plant Growth Regulators
Vegetable Print Presses
County Extension Agents are urged
to register participants in The Institute by
sending the appropriate forms to the
Registrar by May 5, 1989. Again, the
Registrar is Linda Landrum, Horticulture
Agent, 3100 E. State Rd. 44, Deland, FL
32724 (phone 904/736-0624). Registration
fee is $65.00 (non-refundable), payable to:
Florida 4-H Foundation.
(Stephens, Vegetarian 89-04)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. G. J. Hochmu4
Dr. S. M. Olson
Mr. J. M. Stephens
Dr. D. D. Gull
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. S. A. Sargent