SUNIVERSITY OF Cooperative Extension Service
SFLORIDA Institute of Food and Agricultural Sciences
A Vegetable Crops Extension Publication
Horticultural iencc Department DP.O. 110690 Cainefville, FL 32611 Telephone 904/392-2134
April 17, 1995
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
II. COMMERCIAL VEGETABLES
A. Butternut Squash Variety Evaluation.
1" MB. New Transplant Bulletins.
C. Recent Innovations in Strawberry Cooling and Handling.
III. VEGETABLE GARDENING
Note: Anyone is free to use the information in this newsletter.
Whenever possible, please give credit to the authors. The purpose of
i trade names in this publication is solely for the purpose of providing
information and does not necessarily constitute a recommendation of
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I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
May 17, 1995. 41st Vegetable Field
Day, 8:15 AM-4:00 PM. Gulf Coast REC,
Bradenton, FL. (Contact D. N. Maynard).
May 25, 1995. Organic Gardening
Field Day, 10:00 AM 12 noon. Organic
Park, Fifield Park, UF. (Contact J. M.
I. COMMERCIAL VEGETABLES
Butternut Squash Variety
Butternut, as well as other fall and
winter-type squash are grown throughout
Florida in appropriate seasons, but on a very
limited acreage. Accordingly, production data
are not available.
This trial was arranged to evaluate
performance of some butternut inbreds and
hybrids which were developed at the Central
Florida Research and Education Center
(CFREC-Leesburg) with commercial hybrid
and inbred butternut squash varieties in central
and west central Florida.
Butternut squash seeds of 17 entries
were planted in holes punched in the
polyethylene mulch at 3 ft in-row spacing on 3
August at Bradenton. The plots were 15.0 ft
long, had five plants each, and were replicated
three times in a randomized, complete block
design. Weed control in row middles was by
cultivation and application of paraquat.
Pesticides were applied as needed for control
of silverleaf whitefly endosulfann
esfenvalerate), and aphids endosulfann).
Seeds were planted in holes punched in
the polyethylene mulch at 3 ft in-row spacing
on 15 August at Leesburg. The plots which
were 30 ft long and had 10 plants each were
replicated four times in a randomized,
complete block design. Weed control in the
middles was by Curbit and cultivation.
Pesticides were applied as needed to control
pickleworms (methomyl and endosulfan) and
gummy stem blight (chlorothalonil and
Squash were harvested on 4 October at
Bradenton and on 9 November at Leesburg.
Marketable fruit (U.S. No. 1 or better)
according to U.S. grades were separated from
culls (fruit<0.9 lb and/or crookneck) and
counted and weighed.
Plants were rated from 1 (least
resistant) to 5 (most resistant) for downy
mildew on 3 October. The designation of
individual plant appearance ratings was 1 =
dead, 2 = 10% green, 3 = 40% green, 4 = 70%
green, and 5 = 100% green.
Marketable yields in Bradenton ranged
from 5 bu/acre for 'Hercules' to 229 bu/acre
for J25xJ31. The three highest yielding entries
were the J25 inbred and two hybrids with J25
as one parent. In Leesburg, yields ranged
from 70 bu/acre for 'Ponca' to 303 bu/acre for
J25. 'Hercules', a late maturing variety, had a
much higher yield at Leesburg than at
Bradenton. Generally, yields of experimental
lines exceeded those of named varieties. This
could be related to the fact that the named
varieties were developed in more temperate
areas of the country.
Yields obtained in this trial are similar
to those obtained in recent trials in Florida. At
Leesburg, yields ranged from 160 to 452
bu/acre in spring 1988 from 134 to 212
bu/acre in spring 1989, and 33 to 90 bu/acre in
spring 1990. At Live Oak, yields in fall 1990
ranged from 217 to 250 bu/acre.
Grade standards do not provide
guidelines for neck curvature, however,
straightneck butternut fruit are demanded in
most markets and this trait has been selected
for by plant breeders. The proportion of
straightneck fruit at Bradenton ranged from
53% for J22xJ31 to 100% for J25 and
Cull fruit were those judged to be too
small, i.e. less than 0.9 lb or have neck
curvature greater than what would be accepted
in most markets. Using these criteria, the
proportion of marketable fruit at Bradenton
varied from 32% for J21xJ30 to 90% for
J25xJ31. Average weight of marketable fruit
at Leesburg ranged from 0.9 lb for J21xJ30 to
3.0 lb for J25 and J25xJ31.
Downy mildew was prevalent because
of the frequent rains. However, there was a
marked variation among entries in reaction to
downy mildew. In Bradenton, all of the plants
ofJ25xJ32 were dead whereas all of the plants
of J25xJ31 and 'Hercules' were not visibly
affected by the fungus. Factors other than
reaction to downy mildew were related to
yield, however, since the highest (J25xJ31)
and lowest ('Hercules') yielding entries were
the most tolerant of the fungus. Furthermore,
the second highest yielding entry (J25xJ32)
was the most susceptible.
The results of this trial indicated that
butternut squash experimental inbreds and
hybrids developed in Florida perform better
under summer/fall conditions than
varieties/hybrids developed under more
(Maynard and Elmstrom, Vegetarian 95-04)
B. New Transplant Bulletins.
Two transplant publications will soon
be available through the University of Florida.
Production of Vegetable Seedlings: Concept,
Budgets and Cashflow, by David Zimet and
Charles Vavrina reviews the cost of starting
and operating a small greenhouse to produce
vegetable seedlings. An analysis is performed
to determine the cost of producing seedlings
over a 15 year time frame so that cost can be
compared to projected purchase prices. In the
example tomatoes are used, but many of the
production costs would be similar for most
vegetable transplants. This publication was "in
press" at the time of this writing.
An Introduction to the Production of
Containerized Vegetable Transplants, by
Charles S. Vavrina (Bulletin 302) evaluates the
many parameters involved in vegetable
transplant production. Topics range from the
physical to the physiological including
information on greenhouses, benches, trays,
media, seed, fertilization, irrigation, shipping,
production pointers for specific crops, and
much more. This 15 page manual contains 42
references for those wanting more in depth
information. Publication date is mid-April.
These bulletins can be obtained by
calling the University of Florida, Institute of
Food and Agricultural Sciences, Publications
Department at 904-392-1764.
(Vavrina, Vegetarian 95-04)
C. Recent Innovations in
Strawberry Cooling and Handling.
Part 1. Improving Cooling Efficiency
The Florida strawberry industry is
winding up a record 1994-95 season with over
$105 million in total farm gate sales. This
progressive group of growers continues to
explore emerging technologies and techniques
to remain competitive. During this past season
there have been increased sales of specialty
packs, such as the clear, clamshell package
introduced a few years ago by California
shippers, and the adoption of the standard
40"x48" pallet. Although the clamshell
package is popular with consumers and has
brought higher returns to growers, it can
extend the time required for forced-air cooling
by more than 40%. And, as we are all well
aware, to maximize shipping life strawberries
must, first, be rapidly cooled to about 2C
(36F) within a few hours of harvest, and,
second, be maintained at as close to OC (32F)
as possible during subsequent handling and
Recent tests indicated that strawberries
could be hydrocooled, a method which is
significantly faster than forced-air cooling, and
which reduces water loss. This work was part
of the Master of Sciences research of Marcos
D. Ferreira, in cooperation with Jeff Brecht
and myself of the Horticultural Sciences
Department and Jerry Bartz of the Plant
Pathology Department. Hydrocooled
strawberries required only a few minutes to
achieve commercial cooling (7/8 Cooling)
whereas forced-air cooling required an hour or
more. We also determined that hydrocooled
strawberries which were packed wet in pint
baskets did not have reduced shipping life
when directly compared to those which were
forced-air cooled. On the contrary, after
cooling and two weeks storage at 1C (34 F),
hydrocooled fruits had less weight loss (and in
some cases a gain in weight), better color, and
were firmer than those which were forced-air
cooled. Additionally, the two principal
postharvest pathogens of strawberry, Rhizopus
stolonifer and Botrytis cinerea, were
effectively controlled by maintaining free
chlorine at 120 ppm and pH of 6 to 7 in the
Another concern with the use of
clamshell packages relates to quality control.
Growers rely solely on the individual pickers
for every operation from harvest of the
strawberries at the proper ripeness stage to
packaging with minimal mechanical injury.
Packing efficiency and uniformity could be
enhanced through the use of an appropriately
designed packing line. However, this would
require additional handling and increase the
potential for bruising. Next month I will
describe results from other tests related to the
resistance of strawberries to simulated
(Sargent, Vegetarian 95-04)
]I. VEGETABLE GARDENING
Last month I introduced Vermi-
technology as a topic for discussion in a series
of three articles: vermitechnology (March, 95),
vermigardening (April, 95), and vermicom-
posting (May, 95).
As a reminder, in my Vermi-
terminology, vermifarming was defined as
farming with earthworms in the garden.
Notice the similarity to "Earthworm farming",
which is the commercial production of
earthworms. Again, much has been written on
this latter subject, so I do not intend to address
the raising of earthworms for sale.
In this regard, I have received from
nematologist Bob Dunn a copy of a 1978
Wildlife Report on Earthworm Farming in
Florida by the late A. S. "Tony" Jensen. For
those interested, that report (4-78) includes
the following as an outline:
Kinds of worms raised
History and description
Culture bedding, watering, feeding
Storing and handling
Soluble salt injury
An additional excellent reference piece
is Earthworm Biology and Production, IFAS
Cir. 455, 1979. It was authored by J. P.
Martin, Univ. of Cal. This publication
discusses some facts bearing upon the
possibilities ofvermigardening. Some of the
more important effects of earthworms on soil
a) They help decompose organic residues
thus releasing such elements as carbon,
nitrogen, sulfur, and other plant
b) Their body fluids help to dissolve
inorganic plant nutrients in soil
c) The structure of ingested soil is
activated by microbial activity both
while within the worm and later in the
d) The extensive burrowing of the
earthworms improves and maintains
aeration and water penetration.
e) Earthworm feeding helps transfer
digested nutrients from surface litter
further down into the root zone.
A "vermigardener" would therefore try
to take advantage of these improvements in
the soil environment to obtain better plant
growth in the presence of the earthworms.
However, the California circular cautioned
gardeners that although these benefits to the
soil are well known, few valid studies had been
made at that time to show that the presence of
earthworms would actually improve plant
growth. They cited one study (Hopp and
Slater, 1949) which found that growth of
clover was improved by earthworms in a
heavy, clay soil, while in yet another study
(Chadwick and Bradley, 1948), increased crop
productivity could not be demonstrated. Even
today the inoculation of earthworms in the soil
for the purpose of improving production of a
crop is not a common practice.
Having stated the above, it should be
of interest that some gardeners have
successfully utilized earthworms in a grow-box
arrangement for the growing of vegetables.
One such person is vermitechnologist Larry
Martin from Orange Lake, Florida.
A major concern for vermigardeners is
that suitable conditions must be maintained
both for the earthworms and the plants in the
same container or plot, since they are growing
together concurrently. The following are
some of those conditions, and suggestions
from Larry Martin on how he strives to
Temperature Luckily temperatures
ideal for tender vegetables are also suitable for
earthworms. Freezing temperatures kill both,
although the worms can dig deeper to survive
in some cases. Night temperatures should be
60-70F, and daytime temperatures around 80-
907. Bed temperatures should be in the range
Moisture Bed moisture requirements
generally coincide well both for the earth-
worms and the plants. Beds should be
crumbly moist, not soggy. To prevent drying
out and exposure to the hot sun, a mulch of
hay or straw should be used to keep the soil
Alkalinity The pH of the soil best
suited for vegetables is ok for the earthworms.
Thus, the soil may be limed if necessary to
maintain a pH range of 6.0-6.5.
Bed construction For vermigardening
a grow-box is suggested. It should be of
practical dimensions, constructed using 2x12
inch lumber or concrete blocks. A 4x8' or
5x10' size would be best to allow ease of
cultivation. The bed must have a wire cloth
bottom with a maximum of /2 inch squares.
This barrier prevents moles and other animals
from feeding on the worms.
Bedding material The selection of
bedding material is very important to the
survival and activity of the earthworms. The
basic criteria are: 1) It should hold moisture;
2) must remain porous and resist packing; 3)
should be low in protein to prevent excessive
ammoniation; 4) should not contain large
amounts of topsoil; 5) should not contain high
soluble salts; and 6) ideally should be derived
from a composted animal manure combined
with a bulking agent such as straw or a
combination of composted horse manure
mixed with bedding used in the horse stalls.
Stocking the bed Place six to eight
inches of bedding in each bed. Water heavily
for three days to leach out possible chemical
contaminants. Check temperature and if it
remains constant below 807 after 5-6 days,
the bed may be stocked with earthworms.
Add a minimum of 300 worms per
square foot of surface area. Dump them onto
the bedding in the presence of light. Untangle
them and spread them evenly. The worms will
disappear into the bedding to avoid the light.
Water heavily twice a day for the first three
days to settle the worms. Some form of
lighting for the first 10 days will keep the
worms from crawling out.
Feeding Worms are top feeders, so
after 10-14 days the worms will come to the
top to feed. Aged cow manure is an ideal
feed. A small amount of fresh manure may
also be added to increase the nutrient supply.
But there is a wide range of feeds that may be
Planting the vegetables The bed is
ready to plant after 6-8 weeks. Till the worm
bed to a depth of four inches which leaves five
to six inches of worm castings mixed into the
root zone. Seeds or transplants may then be
planted directly into the bed.
After harvest, old plant residue may be
incorporated into the top six inches of the
bedding. Thereafter the worms should be fed
continuously until time for the next planting.
Usually the beds are completely cleaned out
every 6 to 12 months. This rich soil may be
used as a potting soil or soil amendment.
(Stephens, Vegetarian 95-04)
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
Professor & Editor
Dr. J. M. White