UNIVERSITY OF Cooperative Extension Service
SFLORIDA Institute of Food and Agricultural Sciences
i A Vegetable Crops Extension Publication
Horticultural Sciences Department P.O. 110690 Gainaville, FL 32611 Telephone 904/3922134
'k Vegetarian 97-01 January 15, 1997
-_ -- CONTENTS
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
IL COMMERCIAL VEGETABLES
-B. Profitability Improves only when the Soil Test is Calibrated.
C. Seedless Watermelon Variety Trial Results Spring 1996.
W \D. 1997 Florida Postharvest Horticulture Institute and Industry Tour.
SIIL VEGETABLE GARDENING
A. Florida Record-Size Vegetables through 1996.
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.
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
February 4 6, 1997. Weed Science
Society of America. Clarion Plaza Hotel, Orlando,
FL. Contact W. M. Stall. (352) 392-2134 ext.
February 6-7, 1997. Weed Management
and Horticultural Crops Workshop. Clarion Plaza
Hotel, Orlando. Contact W. M. Stall. (352) 392-
2134 ext. 207.
February 19, 1997. Strawberry Field Day,
13138 Lewis Gallagher Rd., Dover, FL. Contact
Dr. Craig Chandler (813) 659-2801.
February 12-13, 1997. FSA/UF-IFAS
Seed Seminar 1997. Radisson Hotel, Gainesville,
FL. Contact D. J. Cantliffe (352) 1928 ext. 203.
March 10-14, 1997. 1997 Florida
Postharvest Horticulture and Industry Tour.
Contact Steve Sargent, Coordinator, Hort. Sci.,
UF, Gainesville (352) 392-2134 ext. 215.
II. COMMERCIAL VEGETABLES
In the December 1996 issue (96-12:2-3), in
the article "Organosilicone Surfactants: The Good,
the Bad. and the Ugly" we referred to Erwinia
stewartii as the pathogen of corn spread by the
organosilicone surfactant. The organism actually
identified was Erwinia chrysanthemi pathovar zeae
(bacterial stalk rot). Our thanks to Ken Pemezny
for pointing out our error.
(Vavrina, Vegetarian 97-01)
B. Profitability improves only when the
soil test is calibrated.
Soil testing is an important tool for
efficient fertilizer management on the vegetable
farm. However, soil testing must be calibrated,
otherwise, it loses its usefulness. A calibrated soil
test can identify those soils that require no
additions of certain nutrients to achieve maximum
yield. For those soils that require fertilization, a
calibrated soil test can accurately predict the
amount of fertilizer to add to achieve maximum
Not all soil tests are calibrated for all soils
in all vegetable growing regions. Calibration of a
soil test requires considerable field research.
Unless there is research documentation for a soil
test procedure, the results of the test and fertilizer
recommendations should be viewed with caution.
There is one aspect of the calibrated soil
test the idea that certain soils do not require any
fertilization that is most difficult for growers to
feel comfortable with. For example, when growers
hear that no phosphorus is needed, they question
whether or not that phosphorus determined by the
soil test is really available. This question is the
heart of a calibrated soil test. To illustrate this
idea, consider the data presented in Figure 1. A
vegetable crop is grown on many soils differing in
extractable nutrient (e.g. phosphorus) from about
2 ppm to 160 ppm. These values are referred to as
the soil test index. Crops are grown on these soils
without P fertilizer. Maximum normal yields were
obtained on soils having 80 ppm P or higher
(without P fertilization). Soils with an index
between 0 and 80 will need some fertilization. So
far, we see the calibrated soil test extractant can
separate soils into those that will respond to
fertilization and those that will not. Those that will
not are high in nutrition and require no fertilizer.
There is enough of the nutrient in question in the
soil to satisfy the crop nutrient requirements for the
whole season. The nutrient is there and it is
available. The soil test showed that the nutrient
was available because we successfully grew
normal crops on those high testing soils without
fertilizer. If a testing laboratory still makes large
fertilizer recommendations for high testing soils,
then the soil test is not calibrated.
For soils in the responsive range, the
calibrated soil test accurately predicts how much
fertilizer will be needed to achieve maximum
yields. Most calibrated soil tests predict less than
50% maximum yields for unfertilized very low
testing soils; 50 to 75% for low testing soils; and
75 to 100% for medium testing soils. To
determine the amount of fertilizer needed for these
soils, fertilizer experiments are needed that
measure the crop response to added fertilizer on
soils with various soil test indices. Data presented
in Figure 2 illustrate this part of the calibrated soil
test. On a low testing soil, crop yield reached
100% maximum yield with 125 lb per acre of a
specific nutrient. However, on a medium soil, only
75 lb of nutrient were needed.
From the above, it should be evident that
considerable research must go into a calibrated soil
Fig. 1. Relative Crop Yield
Relationship With Soil Test Index
"o 70 --E --- -
50 -- -
20 ----- -: -- -
S 10 -=,, -.
0 20 40 60 80 100 120 140 160
Soil Test Index (ppm)
C. Seedless watermelon variety trial
results Spring 1996.
The concept of seedless watermelons was
described first in the U.S. literature by Kihara in
1951 based on experimentation that began in Japan
in 1939. Seed for planting seedless watermelons
results from a cross between a selected tetraploid
female parent, developed by treating diploid lines
with colchicine, and a selected diploid (normal)
male parent. The resulting triploid plants are
sterile and do not produce viable seed. However,
small, white rudimentary seeds develop which are
eaten along with the flesh just as immature seeds
are eaten in cucumber.
Fruit enlargement in normal fruit,
including watermelon, is enhanced by growth-
promoting hormones produced by the developing
seed. Growth hormones are lacking in seedless
watermelons so those agents must be provided by
pollen. Since flowers on triploid plants lack
sufficient viable pollen to induce normal fruit set,
normal diploid seeded watermelons are interplanted
with triploids to serve as pollenizers. An adequate
bee population is necessary to insure that sufficient
transfer of pollen occurs. Seedless fruit (from
test. Using an uncalibrated soil test could be
costing extra money twice, once for the cost of the
test itself, and again for the extra (or inadequate)
fertilizer predicted by the uncalibrated test.
triploid plants) tend to be triangular shaped without
Although the procedure for production of
seedless watermelons has been known for almost
50 years and commercial varieties have been
available for nearly 20 years, the interest in and
acreage of seedless watermelons has remained
small in Florida. Erratic performance, poor seed
germination, high seed costs, and inadequate
varieties resulted in the lack of interest in seedless
Specialty vegetables are in high demand
and seedless watermelons offer an attractive
alternative for discriminating consumers and the
food service industry. Seedless watermelons are
being actively promoted by marketing
organizations and seed companies to stimulate
demand. At the same time, new varieties are being
developed that are superior to those previously
available. Seedless watermelons have been
evaluated at this location annually since 1988.
The objective of this trial was to evaluate
the performance of seedless watermelon varieties
under west-central Florida conditions.
Fig. 2. Relative Crop Yield
Relationship With Applied Fertilizer
810 0. ....
2 20 MED
0 50 100 150 200
Applied Fertilizer (Ib per acre)
Seeds of 38 seedless watermelon varieties
or experimental lines for replicated trials were
planted in a peat-lite growing mix in No. 128 Todd
planter flats (1.5 x 1.5 x 2.5 in. cells) on 17
February. The watermelon transplants were grown
by a commercial plant grower.
Soil samples from the experimental area
obtained before fertilization were analyzed by the
University of Florida Extension Soil Testing
Laboratory: pH = 7.2 and Mehlich I extractable P
= 42 (high), K = 15 (very low), Mg = 115 (high),
Ca = 803 (adequate), Zn = 3.3 (adequate), Cu =
1.8 (adequate), and Mn = 2.5 (deficient) ppm.
The EauGallie fine sand was prepared in
early February by incorporation of 0-1.2-0 lb. N-
P205-K20 per 100 linear bed feet (lbf). Beds were
formed and fumigated with
methylbromide:chloropicrin, 67:33 at 2.3 lb/100
lbf. Banded fertilizer was applied in shallow
grooves on the bed shoulders at 3.1-0-4.3 lb N-
P205-K20/100 lbf after the beds were pressed and
before the black polyethylene mulch was applied.
The total fertilizer applied was equivalent to 148-
60-206 lb N-P205-K20/A. The final beds were 32
in. wide and 8 in. high, and were spaced on 9 ft
centers with four beds between seepage irrigation/
drainage ditches which were on 41 ft centers.
Transplants were set in holes punched in
the polyethylene at 2.5 ft in-row spacing on 26
March. The replicated plots were 17.5-ft long and
had seven plants each and were repeated three
times in a randomized, complete block design.
Standard watermelons that were being evaluated
were direct seeded in beds on each side of two
seedless watermelon beds on 12 March to serve as
diploid pollenizers. Weed control in row middles
was by cultivation and applications of paraquat.
Pesticides were applied as needed for control of
silverleafwhitefly endosulfann and esfenvalerate),
aphids endosulfann), and gummy stem blight
(chlorothalonil and metalaxyl-chlorothalonil).
Watermelons were harvested on 4-10 June
and 19-21 June. Marketable (U.S. No. 1 or better)
fruit according to U.S. Standards for Grades were
separated from culls and counted and weighed
individually. Tetraploid fruit, where they occurred,
were not included in the marketable category
because they are not seedless. Soluble solids were
determined with a hand-held refractometer on at
least six fruit from each entry at each harvest and
the incidence and severity of hollowheart were
noted on these fruit. Where possible, the resulting
data were subjected to analysis of variance and
mean separation was by Duncan's multiple range
Temperature during the experimental
period from 26 March to 21 June was near normal.
Rainfall during the fruit development period was
greater than normal which did not provide good
watermelon growing conditions. Also, there was
considerable plant damage from wind early in the
season which caused plant loss and necessitated
Early yields, represented by the first of two
harvests, ranged from 133 cwt/acre for 95-14 to
352 cwt/acre for 'Favorite Ball'. Thirty-one other
entries had yields similar to those of 95-14 and 33
other entries had yields similar to those of 'Favorite
Ball'. Average fruit weight at the first harvest
varied from 11.6 lbs for 95-14 to 22.7 Ibs for W
0037. Soluble solids concentrations ranged from
11.4 % for 'Jack of Hearts' to 14.4 % for W 0016.
Total yields varied from 243 cwt/acre for
W 5001 to 507 cwt/acre for 'Millionaire', but only
W 5001 and 95-14 had yields that were
significantly lower than 'Millionaire'. Total yields
far exceeded the state average yield of 220
cwt/acre for the 1990-91 to 1994-95 seasons
(Gender and Pugh, 1996). Average fruit weight for
the entire season ranged from 12.4 lbs for 3F 1273
to 20.0 lbs. for 'Ace of Hearts' and W 0037.
Soluble solids concentrations varied from 11.5%
for 'Jack of Hearts' and 'Crimson Trio' to 13.9%
for W 0016. Accordingly, soluble solids in all
entries far exceeded the 10% specified for optimal
use in the U.S. watermelon grade standards to
describe very good internal quality. The incidence
of hollowheart ranged from 0 for 'Millionaire', 92-
08, 'Favorite Ball', W 0037, 3F 1174, and W 4033
to 67% for WM 8009. The severity of hollowheart
varied from 0 for these varieties to 2.3 in. for
Seedless watermelon variety trials have
been conducted at this location each spring season
since 1988. The highest yields ranged from 507
cwt/acre this year to 1161 cwt/acre in 1993. In
spring 1996, the highest yield in the replicated trial
was 507 cwt/acre which was considerably less than
the 811 cwtlacre average high yield of the previous
Varieties producing oval to oblong fruit
may be more suitable for boxing than varieties
producing round melons. Generally, the striped
melons are more attractive for the U.S. market than
those with dark stripes on a very dark green
background, or those with a solid dark green rind.
Based on results of this and previous trials,
varieties, in alphabetical order, that appear to have
considerable potential for commercial production
in Florida include' Crimson Trio', 'Genesis', 'King
of Hearts', 'Millionaire', 'Scarlet Trio', 'Summer
Flavor 5032', 'Summer Sweet 5244', and 'Tri-X-
313'. 'Tiffany' was not included in this trial, but
has performed well in several past trials.
Table 1. Total yields, average fruit weight, soluble solids, and the incidence and severity of hollowheart of
seedless watermelons. Gulf Coast Research and Education Center, Bradenton. Spring 1996.
Queen of Hearts
Summer Sweet 5244
Abbott & Cobb
33 a-d 0.3 d-e
42 a-c 0.9 b-e
Ace of Hearts Petoseed 461 ab 20.0 a 12.8 a-d 42 a-d 0.6 c-e
ASM 5092 American 451 ab 15.8 c-k 12.8 a-e 8 d 0.1 e
Jack of Hearts Petoseed 450 ab 15.2 e-1 11.5 e 40 a-d 0.5 c-e
ASM F464 American 434 a-c 16.7 c-j 13.0 a-c 13 ed 0.1 e
Crimson Trio Rogers 432 a-c 16.8 b-j 11.5 de 58 a-c 2.3 a
RWM 8008 Rogers 427 a-c 15.9 c-k 12.7 a-e 6d 0 e
Tri-X-Shadow American 426 a-c 16.5 c-j 12.3 b-e 17 b-d 0.3 d-e
WM 8009 Rogers 426 a-c 17.9 a-g 13.1 ab 67 a 1.4 a-d
HMX 7928 Harris Moran 423 a-c 15.5 d-l 12.6 b-e 17 b-d 0.3 d-e
Deuce of Hearts Petoseed 409 a-c 15.0 f-I 12.2 b-e 37 a-d 0.7 b-e
Scarlet Trio Rogers 405 a-c 18.3 a-f 12.6 b-e 62 ab 1.6 a-c
King of Hearts Petoseed 399 a-c 15.0 f-I 12.7 a-e 31 a-d 0.5 c-e
W 1025 Pioneer 396 a-c 15.9 c-k 12.2 b-e 8 d 0.1 e
Revelation Shamrock 394 a-c 14.8 g-l 13.0 a-c 8 d 0 e
W 1003 Pioneer 393 a-c 15.0 e-I 13.5 ab 42 ad 0.2 e
3F 1273 Known You 391 a-c 12.41 12.8 a-d 8d 0 e
3F 855 Known You 390 a-c 18.4 a-e 13.1 a-c 58 a-c 1.8 ab
SSC 460066 Shamrock 389 a-c 17.2 a-i 13.1 a-c 17 b-d 0.1 e
Tri-X-313 American 388 a-c 17.2 a-i 12.5 b-e 8 d 0.1 e
Genesis Shamrock 387 a-c 15.5 d-l 12.8 a-e 30 a-d 0.2 e
Table 1 (continued).
Weight Avg. fruit Soluble Hollowheart
Entry Seed Source (cwt/A)' wt (lb) solids (%) (%) (in.)2
W 3053 Pioneer 374 a-c 15.6 c-1 13.0 a-c 36 a-d 0.6 c-e
W 0037 Pioneer 368 a-c 20.0 ab 12.6 b-e 0 d 0 e
W 3022 Pioneer 365 a-c 18.8 a-d 13.0 a-c 25 a-d 0.1 e
Summer Sweet 5544 Abbott & Cobb 358 a-c 16.6 c-i 12.5 b-e 33 a-d 0.7 b-e
95-11 Sakata 357 a-c 15.5 d-1 12.6 a-e 25 a-d 0.6 c-e
3F 1174 Known You 353 a-c 14.4 h-1 12.3 b-e 0 d 0 e
W 4033 Pioneer 339 a-c 17.5 a-g 12.9 a-c 0 d 0.1 e
SSC 856 Shamrock 337 a-c 16.3 c-k 13.5 a-b 8 d 0.1 e
W 0016 Pioneer 328 a-c 14.4 h-1 13.9 a 25 a-d 0.2 e
3F 1004 Known You 323 a-c 14.0 i-1 12.7 a-e 33 a-d 0.9 b-e
W 0038 Pioneer 321 a-c 15.9 c-k 12.3 b-e 28 a-d 0.4 de
95-14 Sakata 302 be 14.9 g-1 12.5 b-e 8 d 0.4 c-e
W 5001 Pioneer 243 c 16.4 c-j 11.8 c-e 38 a-d 0.3 de
'Acre = 4840 lbf.
2Average width of fruit cracks of those fruit sampled.
3Mean separation in columns by Duncan's multiple range test, 5% level.
(Maynard, Vegetarian 97-01)
D. 1997 Florida Postharvest
Horticulture Institute and Industry Tour.
University of Florida, Gainesville
1997 marks the sixth annual Postharvest
Institute & Industry Tour. This year the program
has been reformatted for a 5-day period to better
address the interests and time constraints of
industry professionals. The Institute will be held on
Monday and will be theme-oriented: "Developing
Premium-Quality Programs for Fresh Produce".
It is designed to provide the latest practical
information on determining and maintaining
consistent postharvest quality for tropical/sub-
tropical fruit and vegetable crops destined for
domestic and/or export markets. Participants from
previous Institutes have mentioned that one of the
highlights was the opportunity for networking with
other professionals. A display area will be
available for industry exhibits.
The Postharvest Industry Tour will
provide an opportunity to experience first hand the
latest technologies for the handling and shipping of
subtropical and tropical fruits, vegetables and
ornamental crops. Participants will visit harvest,
packing and shipping and warehousing operations
throughout south and central Florida.
The tour bus will depart from Gainesville
on Tuesday morning and will return to Gainesville
on Friday evening. Tour enrollment will be limited
to 35 persons.
THE DEADLINE FOR EARLY
REGISTRATION IS FEBRUARY 14,1997.
(Sargent, Vegetarian 97-01)
IH. VEGETABLE GARDENING
A. Florida record-size vegetables
January is the month for the biggest weigh-
in of large vegetables held in Florida annually.
This event is conducted during opening day of the
South Florida Fair in West Palm Beach. Each year
of the past decade exhibitors have brought in by the
"roll-it or tote-it" method vegetables ranging from
the lowly radish to the mighty pumpkin. It is not
unusual to see some of the tropicals as well, such
as cassava, calabaza, boniato, cocoyams, and true
yams. The draw is the cash money being offered
as prizes. Winners in two divisions adult and
youth receive the following: 1t place $200; 2n
place $150; 3" place $100; 4th place $75; 5h
place $50; and 6h place $25.
Entries are weighed in on digital scales.
Then a point system is used to calculate an
equivalent rating for all the various items. The
system is based on the average normal size for each
kind of vegetable, and the degree of difficulty in
growing that vegetable to a large size. As an
example, a 1 pound tomato is equivalent to a 36
pound pumpkin or an 18 pound watermelon. Some
of these fair contest winners occasionally break the
state records. The following is a listing of the
current record-holders for vegetables grown in
Florida. Seven new records were set in 1996.
These are listed in bold type.
Florida Record-size Vegetables through 1996
9 1/2 inches
12 lb. 10 oz.
5 lb. 4 oz.
19 lb. 7 oz.
29 lb. 8 oz.
3 lb. 1 oz.
11 lb. 4 oz.
15 lb. 6 oz.
1 lb. 3 oz.
13 ft. 3 in.
1 lb. 15 oz.
4 Ib. 7 oz.
4 lb. 8 oz.
1 lb. 8 oz.
11 lbs. 2 oz.
21 lb. 8 oz.
19 lb. 8 oz.
Okra, pod (wt)
Okra, pod (length)
La. Green Velvet
18 lb. 3 oz.
22 1/4 in.
3 lb. 11 oz.
1 lb. 1 oz.
2 lb. 13 oz.
3 lb. 12 oz.
23 lb. 5 oz.
131 lb. 12oz.
23 lb. 12 oz.
3 lb. 11 oz.
47 lb. 9 oz.
11 lb. 11 oz.
6 lb. 2 oz.
18 lb. 4 oz.
12 lb. 15 oz.
(Stephens, Vegetarian 97-01)
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. S. M. Olson
Mr. J. M. Stephens
Dr. G. J. Hochmuth
Profess & 'to
Dr. S. A. Sargent
Dr. C. S. Vavrina
Dr. D. N. Maynard
Dr. W. M. Stall
Dr. J. M. White