INSTITUTE OF FOOD AND
UNIVERSITY OF FLORIDA
A Vegetable Crops Extension Publication
VegcLable Crops Department. 1255 WSWD Gaincsville, FL 32611 Tclcphone 392-213.
II I II
November 9, 1988
I. NOTES OF INTEREST
___ ----- A. Vegetable Crops Calendar.
II. COMMERCIAL VEGETABLES
A. Production of Seedless Watermelons: Part 3.
B. Collard Variety Trials.
M&, C. IFAS Greenhouse Vegetables Production Handbook.
D. Precooling Cost-Efficiency.
S '--III. PESTICIDE UPDATE
A. Dodder on Pepper in Florida.
IV. VEGETABLE GARDENING
A. Survey Vegetable Gardening in Containers.
S.;) Note: Anyone is free to use the information in this
i. 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 product.
k.. --. -
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
November 15, 1988. Deadline:
for National Gardening Association
Youth Program Grants. (Contact Jim
February 3, 1989. State Master
Gardener Advisory Committee Meeting,
1308 Fifield, University of Florida.
(Contact Kathleen Ruppert).
March 20-24, 1989. Tour -
Commercial Harvesting and Handling of
Horticultural Crops. (Contact Steve
June 19-23, 1989. 4-H Horti-
culture Institute. 4-H Camp Ocala
(Contact Jim Stephens).
II. COMMERCIAL VEGETABLES
A. Production of Seedless
Watermelons: Part 3.
Refer to the September
Vegetarian for information on
development of seedless watermelon
hybrids, the need for and arrangement
of pollenizer rows, and the impor-
tance of adequate bee population for
production of symmetrically-shaped
fruit; and to the October Vegetarian
for seed characteristics and crop
This section will focus on
results of a seedless watermelon
variety trial conducted at the Gulf
Coast Research & Education Center in
the spring of 1988. Seeds of 16
seedless watermelon varieties or
experimental lines were seeded in a
peat-lite growing mix in No. 150 Todd
planter flats on January 26, 1988.
After thorough watering, the flats
were covered with polyethylene and
placed in a greenhouse maintained at
80F. At the first sign of emergence
the polyethylene was removed, and the
temperature was lowered to 70*F night
and 80"F day.
The EauGallie fine sand was
prepared in January 1988 by incorpor-
ation of starter fertilizer. Beds
were formed, fumigated, and banded
fertilizer was applied in shallow
grooves on the bed shoulders after
the beds were pressed and before the
polyethylene mulch was applied. The
final beds were 28 inc. wide and 6
in. high, and spaced on 9 ft. centers
with seepage irrigation/drainage
ditches on 4.5 ft. centers, or every
4 beds. The watermelon transplants
were set in holes punched in the
polyethylene at 4 ft. in-row spacing
on February 29. Icebox watermelons
planted on each side of two seedless
watermelon beds served as polleni-
Watermelons were harvested
three times beginning June 1 and
ending June 23. Marketable melons
were separated from culls and counted
and weighed individually. Soluble
solids determinations were made with
a hand-held refractometer on at least
12 fruit from each entry over two
Early yields based on the first
of three harvests, ranged from 85
cwt/A for CFREC (Central Florida
Research and Education Center
Leesburg) 88-4 to 333 cwt/A for 'Jack
of Hearts'. 'Quality' also produced
high early yields. Early average
fruit weight ranged from 13.0 lb for
CFREC 88-8 to 16.2 Ib for 'Jack of
Total yields ranged from 424
cwt/A for ACX 87m103 t 755 cwt/A for
CFREC 88-7. Other high yielding
varieties were CFREC 88-8, CFREC 88-
2, 'Jack of Hearts', 'Queen of
Hearts', CFREC 88-4, and 'Quality'.
Average fruit weight for three
harvests ranged from 11.7 lb for
'Fengshan No. 1' to 17.0 lb for CFREC
88-4. There was little difference
within varieties in early average
fruit weight or for the entire
Soluble solids were uniformly
high, ranging from a low of 11.5% for
'Fengshan No. 1' to a high of 12.8%
for 'Queen of Hearts'.
Based on this trial, 'Jack of
Hearts', 'Queen of Hearts', and 'King
of Hearts' appear to be the best
available varieties for commercial
production in Florida at the present
time. For more information on this
trial, request GCREC Research Report
1988-18 from the author.
There is considerable interest
in the trade in production and
marketing of seedless watermelons.
Growers should be aware of some of
the difficulties in seedless water-
melon production and precautions
necessary for successful production
as outlined in this series of
(Maynard, Vegetarian 88-11)
B. Collard Variety Trials.
A rather extensive collard
variety trial has been conducted at
the North Florida Research and Educa-
tion Center in Quincy. Trials were
conducted from 1983-1987 with 13
different planting dates. All trials
were replicated 4 times with 25 feet
per plot. In-row spacing was 12
inches and between row spacing was 36
inches except in 13 Feb. 1987 plant-
ing where a double row 14 inches
apart was planted on black plastic
mulch. Total fertilization was 190-
100-220 lb/A (N-Pz05-K20). Dacthal
75W was applied over top at 10 lb/A
for weed control. Irrigation was
supplied as needed by overhead
sprinklers. Transplanting dates were
31 March 1983; 7 Sept. 1983; 25 Jan.
1984; 5 March 1984; 29 Aug. 1984;
Oct. 1984; 4 March 1985; 19 Sept.
1985; 2 Jan. 1986; 20 Feb. 1986; 12
Sept. 1986; 13 Feb. 1987, and 8 Sept.
The results averaged over all
planting dates are presented in the
Collard Variety Trials Quincy (1983-1987)
Number of Number of
different Yieldz times
Variety Source dates cwt/A crates/A first
Blue Maxy Abbott & Cobb 13 352.7 1411 6
HiCropY Parks Seed 13 349.0 1396 5
Heavi-Cropy Abbott & Cobb 13 293.4 1174 0
Morris Heading Northrup King 13 288.8 1155 0
Vates Northrup King 13 279.6 1118 0
Georgia Northrup King 13 276.5 1106 2
America Northrup King 10 265.8 1063 0
Champion Harris Moran 13 262.6 1050 0
Carolina Northrup King 12 220.3 881 0
over number of different planting dates.
The top 3 varieties are hybrids from
Japan. 'Blue Max' was top yielder
with 'Hi Crop' very close behind.
There is very little difference in
yield between these 2 varieties and
of the 13 trials they ranked first 11
times. After these 2, there was a
drop in yield of about 5000 lb/A
before the next variety and the
remaining varieties were fairly
clumped except for 'Carolina'.
'Carolina' placed last in 8 out of
the 12 trials that were planted.
'Georgia' ranked first in 2 of the
trials but its overall yield was
reduced because of severe bolting in
2 of the planting dates where it
ranked last. On 25 Jan. 1984 and 2
Jan. 1986 planting dates, 100 and 85
percent, respectively, of the plants
bolted and were not marketable.
'Champion', an improved 'Vates', had
higher yields in only 3 of the 13
trials but were never significantly
As can be seen from the yield
results, much higher yields can be
realized by the hybrids 'Blue Max'
and 'Hi Crop', but one of the
drawbacks is the much higher seed
costs of the hybrids.
(Olson, Vegetarian 88-11)
C. IFAS Greenhouse Vegetable
Greenhouse vegetable production
in Florida has been increasing over
the last few years. We produce
enough vegetables in greenhouses to
rank Florida near the top in the
nation. Florida has a wide range of
producers ranging from a very large
operation (about 20 acres) to small
producers of 3,00 to 4,000 square
feet. Most of the production is
tomato and cucumber, but there are
significant amounts of other crops
such as lettuce, pepper, and herbs.
Recently, a group of Extension
specialists and county agents went on
a study tour to many northern produc-
tion areas in the U.S. and Canada.
Our attempt has been to better
prepare ourselves to better help our
industry. Presently, we are
authoring a comprehensive handbook
for greenhouse vegetable production
in Florida. The handbook will be
divided into 4 volumes. Volume I
will deal with the decision-making
process and will be a small booklet
to hand to someone who is investigat-
ing greenhouse production potential
for himself. Volume II will deal
with the broad topic of getting
started and building the right kind
of operation from the engineering and
equipping point of view. Volume III
will contain information on the nuts
and bolts of production such as
cultivars, fertilizer, water, polli-
nating, principles of pest control,
and harvesting and handling. Volume
IV will contain the specific labeled
products for pest control (will be a
The authoring is being done by
a large and varied team. Armed with
a little bit of experience and lots
of literature, we hope to assemble a
solid and helpful handbook. To help
us in meeting everyone's needs.
please take the time to fill out
those greenhouse questionnaires the
counties have received. Answers to
the questions will help us provide
the needed information in our
(Hochmuth, Vegetarian 88-11)
D. Precooling Cost-Efficiency.
Perishable vegetables should be
precooled soon after harvest to
preserve quality; rapid precooling
is desired for the more perishable
vegetables, or those that need to be
shipped quickly. However, rapid
precooling systems require greater
refrigeration capacity and electri-
city demand. For those products that
do not require rapid precooling, a
system should be devised that would
be more cost-efficient. Forced-air
cooling is one example of a method to
precool certain vegetables and is a
good example of cost-efficiency,
reported from California (Davis).
Increasing the cooling time should
reduce electricity bills by (a)
reducing electricity demand, (b)
decreasing fan energy use and the
refrigeration needed to remove heat
produced by the fans, and (c)
allowing the refrigeration system to
operate more during the cooler night
hours when it is more efficient.
In the comparison California
used, they forced-air cooled a pro-
duct in 6 or 15 hours which resulted
in the cooler being used for 13 hours
in the fast cooling system and 22
hours for the slow cooling option.
Slow cooling reduced the peak refrig-
eration demand from 160 to 110 tons.
This reduced the electricity bill by
$540 per month based just on demand
charges. They did not estimate the
savings caused by less fan energy use
or by increased refrigeration
efficiency. Slow cooling saved 50
tons of refrigeration capacity. At
today's prices (CA) this could cost
from $60,000 to $100,000.
When planning new forced-air
coolers for commodities that are not
highly perishable (peppers, cucum-
bers, squash), consider slow cooling;
it will allow you to install less
refrigeration equipment. For
existing systems that have extra
cooling capacity, there will be
little or no cost to use slow
cooling. It can be done by just
adding more product to a cooling
location or by using fewer fans.
Some axial flow fans may have their
output reduced by blade pitch
(Gull, Vegetarian 88-11)
III. PESTICIDE UPDATE
A. Dodder on Pepper in
Dodder (Cuscuta sp.) is a true
parasitic plant that is a serious
problem in some areas of the East
Coast. It has also been found spora-
dically in other pepper production
areas of the state.
There are 170 Cuscuta species
that are without exception parasites
which depend on suitable host plants
for their growth. The individual
species mostly prefer a few particu-
lar host plants on which they can
achieve optimal growth, but they can
also parasitize numerous other
plants. Dodder reproduces by seed.
Germination takes place on or just
below the soil surface. Through
circular searching movements, the
leafless seedling must come into
contact with a host plant. Once it
reaches a host plant, it twines
around it and penetrates it with a
In Palm Beach County it was
previously believed that the dodder
seed blew into the pepper plant
holes, after the pepper was trans-
planted. We have now confirmed that
this is not the case. Fumigation
will control any dodder seed that is
in the bed. Seed that is between the
beds is not affected, however. In
fields with a history of dodder
infestation, we identified a large
number of just germinated dodder
seedlings during the middle of
September, 1988. Where the middles
were clean of weeds, these seedlings
would grow for a short time, and when
no host plant could be found, would
Unfortunately, where incomplete
control of eclipta or nightshade was
found, or where weed control was
lacking, the dodder attached to these
weeds, infected them, and then grew
to neighboring plants, also infecting
them. The weeds not controlled in
the middles then were an effective
bridge for the dodder to finally
reach the pepper.
If the dodder reached the pep-
per plants before the weeds in the
middles were controlled, the dodder
would survive the subsequent control
of these weeds. The bridging of
dodder from the row middles to the
pepper takes less than a week. With
the large numbers of dodder seedlings
emerging in the row middles, it does
not take many escaped weeds to allow
subsequent pepper infection.
Unfortunately, there is no
herbicide at the present time that
will selectively control the dodder
and not harm the pepper, after the
pepper is infected. The only
recourse then is to control the dod-
der prior to infection of the crop.
Pre-emergence. One strategy is
to control the germinating dodder
seed in the row middles.
Dacthal has a label on peppers
and although it does not have a
dodder label in pepper, it has dodder
labels in other crops.
Dacthal, at high rates, will
inhibit dodder germination and will
disrupt its growth and infecting
ability. For Dacthal to be
effective, however, it must be
applied just prior to dodder
germination. Extremely close
scouting of fields must be done.
When any dodder is seen to be
germinating, the herbicide should be
Future work is planned to
characterize the conditions for dod-
der germination in Florida.
Predictive models are already
available for swamp dodder in the
North. These do not, however, cor-
respond to the field dodder in
Florida. We do know that dodder ger-
minates by the middle of September,
the exact date in the fall and the
spring dates is not known. Predicting
germination would greatly increase
the probability of controlling dodder
in the middles.
Antor and Dual, which have the
potential for row middle labels in
the future on pepper also have shown
efficacy for controlling germinating
dodder seed. Postemergence trials
with these two herbicides so far have
weeds in the row middles is extremely
important. Many materials that will
burn down the weeds in the middles
will also control dodder. Paraquat
will control emerged dodder plants.
Bioherbicides. Dr. T. A.
Bewick, Vegetable Crops Dept.
Gainesville has isolated a fungus
(Alternaria sp.) from swamp dodder in
Wisconsin. He has also isolated
similar fungi from field dodder in
Florida. The fungus spores, when
sprayed on in great enough quantity
will infect dodder and cause a
disease of the plant great enough to
reduce its potential as a weed. A
patent for this process has been
Future work to commercialize
the bioherbicide is in progress.
(Stall, Vegetarian 88-11)
IV. VEGETABLE GARDENING
A. Survey Vegetable Garden-
ing in Containers.
Throughout Florida and other
states, many gardeners grow vegeta-
bles in a wide assortment of contain-
ers, ranging from small clay or plas-
tic pots up to constructed boxes and
beds. To determine how frequently
this type of gardening is done, and
gather some information about it,
Palm Beach agent Gene Joyner conduct-
ed a mail survey with 120 gardeners
who had attended his spring garden
meeting. Here are the results of the
Ques. 1. How many times have you raised vegetables in containers in the last five
years? never 14; 1 year 6; 2-4 years 6; every year 6
Ques. 2. How many containers? 1-2 7;
3-5 7; 6-10 2; 10 or more 2
What type of containers do you prefer for growing vegetables?
plastic 11; wooden 2; cement/clay 8; glass 0; metal 0
Ques. 4. Vegetables you grow in containers. 1. tomato; 2. pepper; 3. herbs;
4. cucumber; 5. radish; 6. chives; 7. rosemary; 8. eggplant; 9. parsley
How are vegetables started? purchased transplants 18; plants from seed 10
Which materials do you use? purchased soil mixes 15; animal manures 9
peat or sphagnum 6; perlite or vermiculite 5; sawdust of wood shavings 2
Ques. 7. Which fertilizer do you normally use? liquid/soluble 14; slow release 2;
dry (granular) 6
Ques. 8. How often do you water your container vegetables?
every day 4; 4-5 times/week 7; 2-3 times/week 8; once/week 2
Ques. 9. Which pest control methods do you prefer?
chemical sprays 7; mechanical removal 4; combination of both 11
Which insecticides do you used most often? Malathion 5; Kelthane 0
Which fungicides do you normally use? Orthocide (Captan) O; Maneb 2;
Dithane 0; Copper 4; Benlate (Benomyl) 3; premixed combination sprays 5
List the four most aggravating problems.
1. watering schedules; 2. low yield; 3. insects and diseases; 4. weeds.
Give your best estimate of how much total money was spent this year on each
plant in your container garden. (14.97 average)
What was the approximate total amount
container vegetable garden (including
plants, fertilizers, chemicals, etc.).
of money spent in your entire
all costs of pots, soil mixes,
Were you satisfied with the amount of vegetables produced? Yes 12; No 6
Would a ground type garden be higher yielding? Yes 14; No 6
(Stephens, Vegetarian 88-10)
Prepared by Extension Vegetable
Dr. D. J. Cantliffe
Dr. G. J. Hochmuth
Dr. S. M. Olson
Dr. W. M. Stall
Dr. J. M. White
Dr. D. D. Gull
Dr. D. N. Maynard
Dr. S. A. Sargent