UNIVERSITY OF Cooperative Extension Service
i^ FLrTORIDA ------------
SFLORIDA Institute of Food and Agricultural Sciences
SA Vegetable Crops Extension Publication
f l w r Iodticunarl 8ienoae Department P.O. 110690 Gaineavilic, FL 32611 Telephone 904/392-2134
September 18, 1995
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
II. COMMERCIAL VEGETABLES
A. Tomato Culture -- How Does It Affect Yield and Disease?
B. Getting The Most Out Of Strawberry Cooling.
I / III. VEGETABLE GARDENING
A. SP 170, Vegetable Production Guide for Florida: How
SHome Horticulture Agents Might Use This Publication.
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, age, handicap or national origin.
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L NOTES OF INTEREST
A. Vegetable Crops Calendar.
October 22-24, 1995. 1995 Florida
State Horticultural Society Annual Meeting,
October 24-25, 1995. Florida
Agricultural Conference & Trade Show.
March 7-14, 1996. Florida Postharvest
Horticulture Institute and Industry Tour.
Contact Steve Sargent, Coordinator.
H. COMMERCIAL VEGETABLES
A. Tomato Culture--How Does It
Affect Yield and Disease?
Preface: The following was reported
in a New Jersey Extension publication and is
recent info to an often asked question in these
days of declining profitability in tomatoes. Dr.
Jay Scott cautions however that the cultivar
tested here was "designed" for stake culture
and the results of cultivars bred for ground
culture (i.e. those from Dr. Gardener's
program in North Carolina) may be quite
Field studies conducted in New Jersey
in 1993 and 1994 were used to compare fresh
market tomatoes grown on the ground with
tomatoes grown using the short stake cultural
system. The effects of cultural systems on
foliar diseases caused by fungi, yield, and
postharvest fruit rot were determined.
These studies, supported by the New
Jersey Agricultural Experiment
Station/Rutgers Cooperative Extension
Sustainable Agriculture Grant program, were
performed at the Snyder Research and
Extension Farm in northwest New Jersey. The
soil was a Quakertown silt loam. In both
years, 'Celebrity' tomatoes were grown at an
18-inch plant spacing and a 6-foot row
spacing. Both stake and ground tomatoes
were grown using raised beds with black
plastic mulch and trickle irrigation. Staked
plants were pruned to the sucker below the
first fruit cluster. Bravo 720, at two pints per
acre, was used to control disease. The crop
was harvested weekly, graded, and weighed.
During peak harvest, marketable fruit were
stored for one week at 60 to 700F to simulate
grower or consumer practices and then
examined for postharvest fruit loss.
In both years, the incidence of foliar
disease was lower on the stake than on ground
culture plants (Table 1). The major foliar
disease in both years was early blight.
Septoria leaf spot was also present.
Total yield was not affected by culture.
However, marketable yield was higher for the
stake than the ground culture tomatoes (Table
1). In 1994, yield of jumbo fruit was higher
for stake than ground culture plants.
The cultural system had a major effect
on postharvest losses. Ground culture
marketable fruit stored for seven days
averaged 30% loss to various decays. Losses
of stake culture fruit averaged 12.5% (Table
Table 1. Effect of culture on disease, yield and post-harvest losses.
Ground 6.5 b
Stake 4.6 a
Loss due to
Anthracnose, a field initiated decay, is
a primary concern in tomato production. In
our studies, anthracnose accounted for an
average of 6% of the ground culture losses
versus an average of 0.6% of the stake culture
losses. Other losses were due to common
decay organisms that require a microscopic
injury to initiate decay, and consisted
principally of black mold, sour rot, bacterial
soft rot, and rhizopus rot. These were all
lower on stake than ground culture fruit.
These studies clearly demonstrated the
advantages of growing fresh market tomatoes
on stakes. Staking reduces disease incidence,
promotes larger fruit and greater marketable
yields, and reduces postharvest losses from
anthracnose and other common decay
organisms. In fact, culture was more
important than fungicide applications in
reducing postharvest losses.
(Martha Maletta, Hunterdon County
Horticultural Consultant; William H. Tietjen,
Warren County Agricultural Agent;
Winfred P. Cowgill, Jr., Hunterdon County
Stephen A. Johnston, Specialist in Plant
Pathology, New Jersey Grower, Rutgers
Coop. Ext. Newsletter, April, 1995)
(Vavrina and Scott, Vegetarian 95-9)
B. Getting the Most Out of
Recent studies in the Postharvest
Physiology Laboratory have demonstrated the
importance of rapid, thorough cooling of
strawberries and the use of film wraps in
extending fruit quality during simulated
shipping. Tests were also conducted to
determine cooling rates for standard flats and
the newer clamshell containers in standard-
1. Cooling Delays Lower Strawberry
Cecilia Nunes, a doctoral student from
Portugal, has just completed three seasons of
research with Florida strawberries. Along with
Dr. Jeff Brecht from the Horticultural Sciences
Department and myself, Cecilia found that
delays of only 6 hours from harvest were
sufficient to reduce several quality parameters
following a week at 34F and 1 day at 70F. For
example, strawberry firmness decreased by
almost 50% with a 6-hour delay as compared
with those which were immediately cooled.
Likewise, significant losses were found in
ascorbic acid content (Vitamin C), total
soluble solids and bright red surface color
while water loss increased.
The negative effects of the cooling
delay on the above quality parameters were
somewhat offset by overwrapping pint
containers with plastic film. Strawberries
which were stored in overwrapped containers
lost only about 25% of the fresh weight that
unwrapped fruits lost. Although beneficial,
overwrapping did not substitute for rapid
cooling, but in conjunction with rapid cooling,
quality was outstanding.
2. Cooling Comparisons of Mesh and
Plastic Clamshell Containers
This past spring, Drs. Brecht and Mike
Talbot (Agricultural & Biological Engineering)
performed several direct comparisons of these
containers under commercial cooling
conditions. Their tests included mesh
containers in the standard flat (37.5"x39") or
the 12"x20" flat on the 40"x48"pallet, and
clamshell containers (both pints and quarts) on
the standard flat or the 16"x20" flat on the
In all of these combinations, the 7/8
cooling times were fairly similar, ranging from
0.82 hours to 1.1 hours. Assuming
refrigeration capacity is sufficient, the major
cause for delayed cooling reported to us by
many commercial operators appears not to be
due to the clamshell containers, but rather, to
cooler management. The most critical point in
cooling was observed to be failure to seal off
air pathways in the cooling tunnel. The recent
adoption of standard 40"x48" pallets has
extended cooling times by allowing cooler air
to short-circuit through the side openings
under the pallet. In operations where these
openings were not blocked, cooling times
increased by 40%. Gaps between flats or
between pallets also permitted significant air
short-circuiting. For more information
regarding the results of these cooling tests,
contact Dr. Talbot at 904-392-9164.
The results from these series of tests
indicate that strawberry postharvest quality
significantly benefits from rapid cooling within
a few hours of harvest, maintenance of high
humidity during subsequent storage (such as
the use of plastic pallet overwraps) and proper
management of the cooling tunnel.
( Sargent, Vegetarian 95-9)
II. VEGETABLE GARDENING
A. SP 170, Vegetable Production
Guide for Florida: How Home Horticulture
Agents Might Use This Publication.
A new publication has just been
released by the Horticultural Sciences
Department IFAS, University of Florida
(1995). It is SP 170, "Vegetable Production
Guide for Florida", edited by professors Don
Maynard and George Hochmuth, both
Extension Vegetable Specialists with the HOS
Dept. The manual is a compilation of chapters
written by IFAS faculty, and contains
information about the growing and handling of
vegetable crops for commercial purposes.
As Extension agents and specialists we
know that such a guide is For Commercial Use
Only, which means it is not for distribution to
home gardeners. But what of its value as a
reference piece for Home Horticulture Agents?
Does it not contain information that an astute
county agent could interpret and use for his
home gardening program?
With these questions in mind, I have
reviewed SP 170 and within this article shall
endeavor to offer my suggestions on how this
valuable manual may be helpful to our Home
The following is a critique of each
chapter from the standpoint of the information
or portions thereof being helpful to non-
commercial agents, and the precautions
necessary for its use.
Useful to gardeners information
Crops grown in Florida.
Florida's rank as a site of production.
Off-limits (not permitted for gardeners)
Chapter 1. Soil and fertilizer management
Useful to gardeners
Description and adaptability of soil
Soil testing concept (limited value).
Nutrients required by plants.
Nutrient occurrences in soils.
Nutrient levels in soil test (limited).
Tolerance to soil acidity.
Effects on pH by fertilizer and
Fertilizer nutrient sources/contents.
Micronutrients and foliar feeding.
Liquid, dry, and slow-release ferti-
Fertilizer placement and supplement.
Soil preparation and bedding
Plant tissue analysis.
Chapter 2. Variety Selection
Useful for gardeners
Entire section (limited).
Chapter 3. Seeds
Useful for gardeners
Chapter 4. Transplant Production
Chapter 5. Mulching
Chapter 6. Row Covers
Chapter 7. Irrigation management
Table 16. Historical ET values.
Table 17. Crop coefficients.
Chapter 8. Pesticide Safety
Chapter 9. Respiratory Devices for
Use and care of respirators.
Types of respirators.
Off limits information
Chapter 10. Calibration of Chemical
Chapter 11. Insects of Vegetables
Pgs 58-68 describing insects.
Insecticides approved (Caution! -
Agent must not use this section for
recommendations. Use only for
Off-limits information Note:
Agents need to know what is restricted
(R), but must not recommend these
Chapter 12. Nematodes
All sections except 'Chemical Control'.
Chemical Control including Table 23.
Chapter 13. Weed Management
All sections to "Herbicides".
Herbicides, Table 25. Herbicides.
Chapter 14. Yields of Vegetables
All (limited value).
Chapter 15. Postharvest Handling
Chapters 19-37. Crop Fact Sheets
Chapter 17. Production Costs
Chapter 18. Organic production
While this publication (SP170) is
directed toward the commercial grower and
those who advise them, about 3/4 of the
information is general enough to be of value to
home gardeners and those who advise them.
Since the home gardener is likely to
misinterpret the information, the publication
should be used only by Extension workers
who can read and interpret properly (in my
opinion). With that precautionary statement,
I feel SP170 is valuable as a for-sale reference
piece that belongs on the desk of home
horticulture Extension agents as well as
commercial Extension agents.
(Stephens, Vegetarian 95-09)
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
Assoc. Professor & Editor
Dr. C. S. Vavrina
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. J. M. White
Chapter 16. Marketing Strategies