1 UNIVERSITY OF Cooperative Extension Service
FLORIDA Institute of Food and Agricultural Sciences
A Vegetable Crops Extension Publication
fHorticultural cicncc Dcpartment P.O. 110690 Gaincsvillc, FL 32611 Teephoune (352)392-2134
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
II. COMMERCIAL VEGETABLES
A. Sustaining Vegetable Production in Florida In-Service Training
B. Sap Test Meters Ideal for Post Plant Fertilizer Management in
Sandland Sweet Corn Production.
C. 1998 Florida Postharvest Horticulture Institute.
D. Evaluating Muskmelon as an Alternative Greenhouse
III. PESTICIDE UPDATE
A. Florida Weed Science Society.
B. Weed Interference: A Major Problem in Sustainable and
Organic Production Systems.
IV VEGETABLE GARDENING
A. Planting Spring Potatoes? First, Amend the Soil!
S 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 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.
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I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
February 26 27, 1998. Florida Weed Science
Society's 21" annual meeting. Eustis Elks'
Lodge, 2540 Dora Ave.,Tavares, Florida.
Contact Bob Stamps, CREC, Apopka (407)884-
March 7, 1998. Urban Farming
Workshop. Seminole County Extension
Auditorium, Sanford. Contact Richard Tyson at
(407-323-2500 ext. 5554).
March 9-13,1998. Florida Postharvest
Horticulture Institute and Industry Tour. Contact
Steve Sargent, UF, (352) 392-2134 ext. 215.
Contact the author for reports.
1997 Potato Variety Trials. HAS 97-2. D. P.
Weingartner. Hastings Research and Education
1997 Florida late blight summary and results of
1997 folier fungicide and seed piece fungicide.
HAS 97-1. D. P. Weingartner. REC Hastings.
Summary of 1997. Nematode Experiments. HAS
97-3. D. P. Weingartner. REC Hastings.
Weed management in vegetable crops 1998. SS-
HOS-506. W. M. Stall. Horticultural Sciences
I. COMMERCIAL VEGETABLES
A. Sustaining vegetable production in
Florida in-service training agenda.
April 28-30, 1998-IST#874:
Seminole County Extension Auditorium
250 W. County Home Rd., Sanford, Florida
407-323-2500 ext. 5554
Tuesday, April 28: Organic Vegetable
Production in Florida
1:00 pm Introduction & announcements.
Dr. Marion White
1:10 Overview of organic practices, status of
farms, marketing, and current regulations.
2:00 Nematode management options for organic
growers. Dr. Bob McSorley
3:15 Winter legumes as fertilizer sources and
conservation tillage for vegetables in Florida. Dr.
4:30 Insect control for certified organic growers-
what is available and does it work.
Dr. Phil Stansley
6:30 Dinner and discussion
Wednesday, April 29: Alternative
Sustainable Vegetable Production
8:30 am Introduction & announcements.
8:40 The current status of greenhouse vegetable
production in Florida. Bob Hochmuth
9:10 Low-tech, non-circulating hydroponics.
9:40 Tour of area vegetable greenhouse operations.
11:45 Lunch on your own
1:15 pm Tour continued
2:45 Sandland carrot production.
Dr. Jim Strandberg & Dr. George Hochmuth
3:30 Soil solarization and other alternative
approaches for management of soil born pests.
Dr. Dan Chellemi
Thursday, April 30
8:30 am Program planning, administration, and
discussion. Dr. Steve Olson & Dr. Ken Pernezny
(R. V. Tyson, J. M. White, Vegetarian 98-02)
B. Sap test meters ideal for post plant
fertilizer management in sandland sweet corn
Now that the buyout of the Zellwood
muck farms by the St. Johns Water Management
District is almost complete, there may be
marketing opportunities for sandland corn
production in the 1998-99 growing season.
Zellwood muck farms grew seven thousand acres
of sweet corn during the 1995/96 season.
Recent trials at the Central Florida Research and
Education Center in Sanford showed that as
nitrogen rates increased, sweet corn yields
increased (Table 1). Excessive rain during
growing season resulted in the highest yields being
obtained at the 225 lb/acre rate which confirms the
IFAS rain rule (Additional supplemental sidedress
applications of 30 lb N and 20 lb K20 per acre
should be applied only after rainfall/irrigation
amounts that exceed 3 inches within a 3-day period
or 4 inches within a 7-day period).
Cardy meter sap test results showed similar
trends compared to the tissue analytical Lab results
obtained from the same samples at the University
of Florida (Table 2). It only takes about 5 minutes
to get Cardy meter sap test results and they can be
conducted from the seat of a pickup truck. The
Lab results take from 3-4 weeks. For short season
vegetable crops the choice is obvious.
Cardy meters can also be used for soil N
and K analysis if you order the appropriate
accessaries. They can be purchased from Spectrum
Technologies (800-248-8873), from Crop King
(330-769-2002) or from Hydro-Gardens (800-634-
6362). Cost is about $320 each.
Table 1. Nitrogen (N) rates and sweet corn yield and several quality measurements at Sanford, FL,
N Crates/ Husk
lb/acre acre& Wt. (Ib) Cover" Tip fill Length Width
225 326 ay 0.7 a 4.5 a 5.0 a 7.1 a 1.9 a
150 252 b 0.7 a 4.4 a 5.0 a 7.1 a 1.8 a
75 48 c 0.6 b 2.8 b 2.9 b 4.3 b 1.1 b
0 0 0.0 0.0 0.0 0.0 0.0
zExpressed as 42-lb crates.
7Mean separation in columns by Duncan's Multiple Range Test, 0.05 level.
"Husk cover: 1= protrudes, 5=wrapped tightly, completely covered.
"Tip fill: 1=at least 1 inch unfilled: 5=full at top.
'No marketable yield for 0 N, therefore, no data.
Table 2. Nitrogen (N) rates and leaf-N on three dates for sweet corn, Sanford, FL, spring 1996.
Days after planting
Cardv (pDm NO,-Ny Lab (% TKN'Y
lb/A 27 40 49 27 40 49
225 802 aY 535 a 193 a 4.5 a 3.3 a 3.7 a
150 780 a 346 b 169 b 4.2 a 3.0 a 3.0 a
75 474 b 128 c 140 c 3.4 b 2.4 b 2.4 b
0 138 c 77 c 127 c 1.7 c 1.6 c 1.4 c
zCardy ion specific meter, Spectrum Technologies, Inc., Plainfield, IL
YMean separation in columns by Duncan's Multiple Range Test, 0.05 level.
XUniversity of Florida's Analytical Research Laboratory, Gainesville, total Kjeldahl nitrogen.
(R. V. Tyson, J. M. White, Vegetarian 98-02)
Developing Premium-Quality Programs
for Fresh Fruits and Vegetables"
March 9, 1998
University of Florida
282 Reitz Union, Campus
8:15 Welcome and Introduction
Dr. Steve Sargent, Institute Coordinator
8:30 Featured Speaker:Ms. Edith Garrett,
President, International Fresh-cut
"Fresh-cut Produce: Trends and
Session 1: Challenges Facing The Produce
9:00 Current Status and the Future of
Dr. Dan Cantliffe
Chair, Horticultural Sciences
Department, University of Florida
9:25 Current and Future Trends for Fresh
Mr. Dennis Broadaway,
General Manager, Haynes City Citrus
9:50 Strawberry Production and Future
Dr. Chip Hinton
Executive Director, Florida Strawberry
Session 2: Premium Quality: What is it and
How can it be improved?
10:30 Postharvest Quality: The Physiology of
Dr. Greg McCollum, USDA U.S.
Research Horticulture Laboratory, Orlando
10:50 Premium Quality Programs for Fruits
Dr. Steve Sargent, Horticultural
11:10 Evaluating Postharvest Flavor
Dr. Elizabeth A. Baldwin, Research
Horticulturist, USDA Citrus &
Subtropical Products Laboratory, Winter Haven
11:30 Breeding Fresh-Market Tomatoes for
Improved Postharvest Quality
Dr. Jay Scott, Gulf Coast Research &
11:50 Improving Postharvest Quality of
Genetically Modified Horticultural
Dr. Harry Klee, Horticultural Sciences
Arredondo Room 4th Floor, Reitz Union
Session 3: Technologies for Premium Quality
1:40 Recent Progress in Mechanical
Harvesting for Citrus
Dr. Galen Brown, Florida Department
of Citrus, Lake Alfred
2:00 Advances in Automated Sorting and
Dr. Bill Miller, Citrus Research
&Education Center, Lake Alfred
2:20 Trends in Postharvest Treatments
Dr. JeffBrecht, Horticultural Sciences
Department, University of Florida
2:40 Predicting Tomato Sensory Quality
Using "Electronic Nose" Technology
Mr. Fernando Maul, Horticultural
SESSION 3: Ensuring Produce Safety
3:15 Trends in Fresh Produce Regulation
Dr. Doug Archer, Chair, Food Science
& Human Nutrition Department
3:40 Case Studies in Food-borne Illnesses
from Fresh Produce
Mr. Alan Rowan, Bureau of
Florida Department of Health,
4:10 Managing Microbes in Postharvest
Dr. Jerry Bartz, Plant Pathology
4:30 Applying HACCP Principles to
Dr. Charlie Sims, Food Science &
Human Nutrition Department
4:50 Discussion and Wrap-up
(Sargent, Vegetarian 98-02)
D. Evaluating muskmelon as an
alternative greenhouse hydroponic crop.
A specialty muskmelon culture evaluation
was conducted in a 22 x 60 ft greenhouse covered
with two layers of polyethylene. The greenhouse
was located at the Suwannee Valley Research and
Education Center near Live Oak, FL. Seed of a
green-fleshed muskmelon, cultivar,' Gallicum',
was seeded directly into lay-flat bags ofperlite on
March 21, 1996. Four production bags were
seeded with 3 plants per bag and four bags with 2
plants per bag to compare plant spacing. A dilute
nutrient solution was used during the first week of
growth, after which a complete nutrient solution
with 135 ppm N and 230 ppm K was applied. The
irrigation system was controlled by a starter tray
system providing nutrient solution, as needed,
On April 24, the first female bloom
opened and was receptive to pollen. A small artist
paint brush was used to move pollen from male to
female blooms. Receptive female blooms were
checked daily and pollinated. Male blooms were
borne on the main stem and the female blooms
were borne on a short (6-12 inch) side branch.
Each plant was trained up a string to an overhead
cable, seven feet above the production bags.
Once the plant reached the top of the
cable, it was trained along the cable for 8 to 12
inches and then let drop down toward the floor.
As the growing point reached the floor, it was
pinched out to terminate new growth. Insects
were controlled with applications of an
insecticidal soap as needed. Observations on
diseases were also made during the season.
As fruit grew to the size of a baseball,
they were supported in a sling made of either
women's hosiery or soft polypropylene row cover
material. Fruit were harvested at full slip,
counted, weighed, and graded according to
Overall marketable production was 1.8
fruit per plant and cull production was 0.5 fruit
per plant. The US No. 1 fruit yield was 1.4 fruit
per plant and US No. 2 was 0.4 fruit per plant.
Average weight for US No. 1 fruit was 3.7 lbs and
US No. 2 was 2.5 lbs.
Production per plant was similar for plant
populations of three vs. two plants per bag.
Populations of three plants per bag produced 2.17
fruits per plant versus 2.38 fruits per plant for two
plants per bag. Average fruit weight was also
similar between the two populations. Average
fruit weight was 3.16 lbs for three plants per bag
and 3.29 lbs for two plants per bag. Therefore,
populations of three plants per bag will result in
higher yields for the space without sacrificing
Fruits were graded as a cull for two
reasons: (1) a slick, poorly netted fruit, or (2)
fruit rot from gummy stem blight (Didvmella
brvoniae). Poorly netted fruit had very poor taste
and low soluble solids. Plants in this trial were
highly susceptible to gummy stem blight. In
addition to fruit lesions and infection, several
stem lesions per plant were found. Due to the
lack of effective fungicides labeled for
greenhouse muskmelon, gummy stem blight could
be a serious threat to successful production. A
second disease concern was powdery mildew,
(Qidium sp.). Powdery mildew seemed less
important than gummy stem blight, however, both
were a concern.
Primary insects pests included silverleaf
whitefly (Bemesia argentifolii) and several
species of aphids. A high population of the
parasitic wasp (Diaeretiella rape) naturally
developed in the greenhouse and maintained the
aphid population at a manageable level. In
addition to concerns of gummy stem blight, the
overall quality of the fruit was somewhat poorer
than typical field production. Greenhouse-grown
fruit was not as well netted, and lower in soluble
solids than field-produced fruit.
(Robert Hochmuth, Vegetarian 98-02)
II. PESTICIDE UPDATE
A. Florida Weed Science Society
Florida Weed Science Society's twenty-
first annual meeting will be held Thursday and
Friday, February 26 and 27, 1998. The meeting
will be held at the Elks' Lodge, just west of
Highway 441 in Eustis, Florida. Registration is
$20 and includes dinner.
The Thursday morning session is a
workshop on application technology. Topics
include: Computer controlled sprayers, nozzle
choices, drift reduction, calibration and
monitoring techniques for commercial and
research sprayers. There will be 3.5 total CEU's
Restricted Use Pesticide License (RUPL) and 2.5
IPM CEU's for Certified Crop Advisors (CCA).
The Thursday afternoon session will be
talks on various topics such as the CCA program,
WPS, Food Quality Protection Act, invasive
plants and weed management topics. CEU's will
be 4.5 total for RUPL and 3.5 for CCA.
Friday morning the sessions will continue
with more topics on herbicide technology, and
weed management techniques. The topics will be
more for the right-of-way and ornamental and turf
area and 4.0 CEU's will be given for right-of-way,
ornamental and turf and demo/research in the
RUPL. 3.5 CCA will be given for IMP and crop
protection. For more information contact Bob
Stamps. Preregistration is until February 16" or
you may register at the door, Eustis Elks' Lodge,
2540 Dora Avenue, Tavares.
(Stall, Vegetarian, 98-02)
B. Weed Interference: A major
problem in sustainable and organic production
Studies around the country as well as in
Canada and Australia have shown that weeds are
the most difficult management problem in
sustainable and organic production systems. An
eight year study was carried out in California by
the Sustainable Agricultural Farmings Systems
(SAFS) project on corn and tomatoes. In these
studies conventional or Best Management
Practices was compared along with low-input
(sustainable) production and organic production.
SAFS scientists found that weeds were
the pest variable directly associated with reduced
yields. In corn, weed competition reduced yields
in both the low input and the organic systems, and
weed management accounted for the bulk of pest
management costs in all three tomato systems.
The low-input weed control methods used
in the California studies were the use of cover
crops and reduced herbicides. Teasdale (USDA-
ARS, Weed Science Lab, MD) has pointed out
that in a cover crop-weed management system,
weed control is species specific in relation to the
cover crop used and weed species to be
suppressed. Also in a cover crop or a living
mulch system weed control is usually incomplete.
The use of cover crops has distinct
advantages, such as building organic material in
the soil, suppressing soil borne insect, nematode
and/or disease pests, reducing wind or water
erosion along with numerous others.
Cover crop usage to suppress weeds, and
reduce weed seed bank build up should be used
more in Florida vegetable fields. A great deal
more work needs to be done to identify cover crop
type to weed species suppressed, however. An
interesting observation by Jim Fletcher in
Madison County illustrates this point. One of his
growers plants rye between the mulched beds of
tomato and pepper. The rye is allowed to grow to
the height of 6-8 inches before it is killed. The
primary use is to keep the soil in the middles from
blowing and damaging the crop during the high
spring winds. Jim noticed that many weeds did
not emerge through the rye stubble until much
later in the season than normal. This fact has
reduced the row-middle herbicide use by the
grower at least in half.
We are gaining more knowledge on crop-
weed interactions that are needed to develop
sustainable weed management techniques. Acase
in point is open bed watermelon production in
Florida. A study by Ernie Terry has shown that
smooth amaranth (pigweed) must be controlled
from 5 days after watermelon emergence until
approximately the time when the watermelon
vines run off the bed (3 to 4 weeks) to eliminate
yield loss. After 4 weeks, smooth amaranth
emerging in the field will not reduce yield.
Another study showed that, two cultivations (hand
hoeing in the bed) is just as affective in reducing
yield loss from broadleaf weeds as pre plus
postemergence herbicide usage. The hoeing,
however, must be early enough to control the
weeds the first week.
Grasses must be controlled from 4-6
weeks after watermelon emergence to eliminate
yield losses. Early grass weed emergence will not
reduce yields as soon as broadleaf weeds will.
The problem occurs with yellow nutsedge
competition in watermelon. Preliminary work in
Gainesville and Quincy indicates that 50 nutsedge
per square meter (5/ftz) will eliminate marketable
yield of spring watermelon. Cultivation or hand
hoeing is not effective in eliminating the weed in
the bed. Unfortunately also there is no herbicide
to control nutsedge in watermelon at the present
Work is underway at the University of
Florida and at other Southern Universities to
establish the critical period of weed-crop
interference so that control methods, will reduce
or eliminate yield loss.
Correct timing of control, whether it is
chemical (herbicides), mechanical or cultural, is
essential to eliminate yield losses in conventional,
sustainable and organic production systems.
(Stall, Vegetarian 98-02)
IV VEGETABLE GARDENING
A. Planting Spring potatoes? First,
amend the soil!
Organic wastes should be used liberally in
vegetable gardens for at least three very good
reasons: 1) they contribute valuable benefits as
soil amendments and fertilizers; 2) they serve well
as mulching material; and 3) the gardening use of
these wastes helps solve a disposal problem for
society. Amending garden soils has shown to be
one excellent way to recycle these waste products
effectively. Previous trials at the Organic
Gardening Research and Education Park have
strongly indicated that 20 to 40 tons/acre of yard
waste compost, supplemented with organic
fertilizer or animal manure and incorporated
annually, resulted in very satisfactory production
of several garden vegetables. One dozen 5x10 ft
"grow-boxes" were amended annually with a
variety of organic materials. The purpose was to
determine and demonstrate optimum amounts of
these amendments as a source of fertility for
growing garden vegetables.
The spring 1997 study with potatoes
constitutes the subject of this article. The most
recent amendment applications were made in the
spring of 1996 in a trial with 'Celebrity' tomato
and 'Jupiter' pepper. None was applied in 1997.
Therefore, the objective of the 1997 study was to
observe the residual effects of previously applied
amendments on the yield of two potato varieties:
'Kennebec' (white) and 'Red LaSoda'.
Over the course of the seven year period
from 1990-1996, the following amendments were
applied at both a low and a high rate: oak leaves,
yard waste compost (YWC); YWC plus organic
fertilizer (Fertrell 3-2-3); organic fertilizer
(Fertrell 3-2-3); chicken manure; composted
chicken manure (Red Rooster 2-3-2 and 3-5-3);
and combined amendments (sheep
Potatoes were dug 14 May 1997 and the
yield results were recorded as number and weight
of tubers per plant. Top yields of both varieties
came from the mixed-amendments box, which
had received approximately 560 tons/acre (28
lb/sq ft) of organic amendments over the 7-year
period. This box has been tops with all crops
grown in previous years. The box receiving the
higher rate of Red Rooster (4.70 lb/sq ft) gave a
relatively good yield of 'Red LaSoda' tubers, but
only fair yield of 'Kennebec'. Other amendments
(residual) gave fair to poor results. Surprisingly,
yields from the box receiving oak leaves alone (6-
12 lb/sq ft) were as substantial as those from all
but the two highest yielding treatments
One might conclude from this study that
many organic soil amendments, even oak leaves
that are woody and low in N, when applied
seasonally and liberally, tend to provide residual
benefits for a crop like potato and perhaps others.
(Stephens, Vegetarian 98-02)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. G. J. Hochmuth
Dr. S. M. Olson
Mr. J. M. Stephens
Dr. S. A. Sargent
Dr. C. S. Vavrina
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. J. M. White