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Title: Vegetarian
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Creator: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
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Publication Date: August 1999
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SUNIVERSITY OF Cooperative Extension Service
SFLORIDA Institute of Food and Agricultural Sciences


VEGETARIAN

A Vegetable Crops Extension Publication
iHoticubltll cancera s Dpartmant P.O. 110690 Gaincaville, F 32611 Tclphonc (352)392-2134


Vegetarian 99-08


August 1999


CONTENTS


VEGETABLE CROPS CALENDAR

Florida Pecan Field Day

Tomato Institute Program


COMMERCIAL VEGETABLES

# Plant Nutrition Impacts on Vegetable
Quality

# Tomato Varieties for Florida

# Phosphorus Availability and Response
of Tomato to Phosphorous Fertilizer in
Calcareous Soils

VEGETABLE GARDENING

Florida s Largest Pumpkin

Note: Anyone is free to use the information in this newsletter. Whenever
possible, please give credit to the authors. The purpose oftrade 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 Agriculural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to pnwide research, educational
intormatnon and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.
C( MPFR ATTVF FXTENSION WORK IN AGRICULTURE HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA.







VEGETARIAN NEWSLLITER August 1999


The Vegetarian Newsletter is now available on the
internet. The website is
http://www.hos.ufl.edu/aihweb/veaetarian.htm



Vegetable Crops Calendar



Florida Pecan Field Day. Thursday, September 2,
1999. Monticello Country Club; Monticello, FL.
Contact Tim Crocker (352) 392-2134 x 310.

Tomato Institute Program. September 8, 1999.
Ritz Carlton, Naples, FL. Contact Charlie Vavrina
(941) 658-3400.


Commercial Vegetables



PLANT NUTRITION IMPACTS
ON VEGETABLE QUALITY

The use of fertilizers is an important component
of commercial vegetable production. Fertilizers replace
nutrients removed during harvest and allow growers to
manage crop nutrition for maximum yield. Historically,
most vegetable nutrition research focused on fertilizer
rates, nutrient availability to the plant, nutrient effects on
crop growth and yield, and nutrient movement within the
soil. Fertilization practices can also have significant
impacts on harvested fruit quality and quality retention
during packinghouse operations and distribution. These
include physiological disorders, disease susceptibility
and compositional and textural changes. Only relatively
recently has research into plant nutritional effects on
vegetable quality been conducted in earnest and there is
still much to be learned.

Although fruit quality usually increases as soil
nutrient levels increase from deficient to optimum levels,
nutrient levels that produce maximum yield may not
always correspond to levels that result in the highest fruit
quality. Further, although the addition of nutrients above
optimum levels often does not reduce yields, they can
have either negative or positive effects on aspects of
quality that are not readily apparent. Plant nutritional
factors are only one link in the overall process of
producing high quality vegetables. Other critical factors
such as variety selection and environmental conditions
should not be overlooked. Although specific responses
will vary from crop to crop, this article will briefly discuss


some of the general affects that some fertilizer
nutrients have on the postharvest quality of vegetables.

Nitrogen: Adequate nitrogen is essential for optimal
plant growth and development and it is the mineral
element used most by plants. Nitrogen is an important
constituent of proteins and plays a critical role in a
cell's biochemical machinery. Besides reduced yields,
low nitrogen levels generally result in less protein
content in harvested vegetables and inferior quality.
Adequate nitrogen usually allows plants to grow,
develop and produce maximum yields with at least the
potential for a high-quality product with desired color,
flavor, texture, and nutritional composition.

Excessive soil nitrogen can negatively impact
quality in several ways. High nitrogen can result in
compositional changes such as reduced ascorbic acid
(vitamin C) content, lower sugar content, lower acidity
and altered ratios of essential amino acids. In many
vegetables, especially leafy green vegetables grown
under low light, it can result in the accumulation of
nitrates in the plant tissue to unhealthy levels. High
nitrogen fertilization can lead to reduced volatile
production and changes to the characteristic flavor of
celery. In table beets, high nitrogen can leads to
increased glutamine levels which results in off flavors
in the processed beet puree. Other effects of
excessive soil nitrogen include delayed maturity,
increased weight loss during storage of sweetpotato
and increased disorders such as hollow stem of
broccoli and increased soft rot during storage of
tomatoes.

Phosphorous & Potassium: Phosphorous (P) is an
important component of plant DNA, cell membranes,
and energy-yielding intermediates of photosynthesis
and respiration. Potassium (K) plays and important
role in osmotic (water potential) regulation of cells and
in activating different enzymes in photosynthesis and
respiration. As far as fruit quality goes, high P levels
have been reported to increase sugar content,
decrease acidity and alter color of vegetables. High K
levels have often been associated with improving
quality of vegetable crops. High K has been reported
to increase vitamin C content, increase titratable
acidity, and improve color. Greater rates of K
fertilization have also been associated with decreased
blotchy ripening of tomato.

Calcium: Calcium is an important component of plant
cell walls and is required to carry out normal functions
of cell membranes. Since cell walls and membranes
are rapidly synthesized at the growing points of a plant,
they are the first to show deficiency symptoms. Unlike
N, P or K, however, calcium is very immobile within a
plant and cannot be transported from older tissues to


August 1999


VEGETARIANNEWSLETTER







VEGETARIAN NEWSLETTER August 1999


growing tissues during times of deficiencies. Therefore,
the time of calcium availability to the plant can have
important implications in the amount of calcium that
winds up in a specific plant part. Calcium deficiencies
can be common in vegetables, which results in a number
of disorders such as blossom-end rot of tomato, pepper,
and watermelon; brownheart of escarole; celery
blackheart; and tipbur of lettuce, cauliflower and
cabbage. Conversely, high calcium levels will reduce
these disorders and have been associated with other
positive effects such as increased vitamin C content,
extended storage life, delayed ripening, increased
firmness and reduced respiration and ethylene
production.

Micronutrients: Specific effects of both micronutrient
deficiencies and toxicities have also been described and
are associated with specific crop disorders. For
example, boron deficiencies can result in blackheart of
beet, celery cracked stem, internal browning of turnip
and brown curd and hollow stem of cauliflower. As more
research is conducted on plant fertility effects on all
aspects of vegetable quality (flavor, composition, texture,
storability, etc.), growers will be equipped to make better
management decisions to produce crops that best satisfy
the needs of a particular consumer.

(Ritenour, Vegetarian 99-08)


TOMATO VARIETIES FOR FLORIDA

Variety selection, often made several months
before planting, is one of the most important
management decisions made by the grower. Failure to
select the most suitable variety or varieties may lead to
loss of yield or market acceptability.

The following characteristics should be
considered in selection of tomato varieties for use in
Florida.

Yield: The variety selected should have the potential
to produce crops at least equivalent to varieties
already grown. The average yield in Florida is
currently about 1300 25-pound cartons per acre. The
potential yield of varieties in use should be much
higher than average.

Disease Resistance: Varieties selected for use in
Florida must have resistance to Fusarium wilt, race 1
and race 2; Verticillium wilt (race 1); gray leaf spot; and
some tolerance to bacterial soft rot. Available
resistance to other diseases may be important in
certain situations.


Horticultural Quality: Plant habit, stem type and fruit
size, shape, color, smoothness and resistance to
defects should all be considered in variety selection.

Adaptability: Successful tomato varieties must
perform well under the range of environmental
conditions usually encountered in the district or on
the individual farm.

Market Acceptability: The tomato produced must
have characteristics acceptable to the packer,
shipper, wholesaler, retailer and consumer. Included
among these qualities are pack out, fruit shape,
ripening ability, firmness, and flavor.

Current Variety Situation

Many tomato varieties are grown
commercially in Florida, but only a few represent
most of the acreage.

'Florida 47' was grown on about 23% of the
acreage in Florida in the 1998-99 season a notable
increase from the approximately 15% of the acreage
the previous season. Florida 47 was grown on about
36% of the acreage in southwest Florida and 17% of
the east coast acreage.

'Agriset 761' had 14% of the statewide
acreage, down from 22% the previous season.
'Agriset 761' remained popular on the east coast with
33% of the acreage and in southwest Florida with
17% of the acreage.

'Sanibel' and 'Solimar' each had about 11%
of the state's acreage. 'Sanibel' was the
predominate variety in Dade County with 65% of the
acreage there. 'Solimar' was planted extensively on
the east coast with 41% of the acreage while it
accounted for about 12% of the west central Florida
acreage.

Other varieties with significant acreage in the
1998-99 season were 'Solar Set' (8%), 'BHN 22'
(5%), 'Sunbeam' (5%), other BHN varieties (4%) and
'Sunpride' (2%). 'Solar Set' and BHN were most
popular in southwest and west central Florida.
'Sunbeam' and 'Sunpride' acreage was mostly in
west central Florida. Many other varieties and
advanced experimental hybrids were grown on less
than 1% of the state's acreage.

Tomato Variety Trial Results

Summary results listing the five highest
yielding and the five largest fruited varieties from
trials conducted at the University of Florida's Gulf
f.na:t Re~earnh and Education Center. Bradenton;


VEGETARIAN NEWSLETTER


August 1999








VEGETARIAN NEWSLETTLR August 1999


Indian River Research and Education Center, Fort
Pierce; Tropical Research and Education Center,
Homestead; North Florida Research and Education
Center, Quincy; and Palm Beach County Cooperative
Extension Service, Delray Beach for the Spring 1998
season are shown in Table 1. High total yields and
large fruit were produced by 'BHN 22' and 'Equinox' at
Bradenton, 'Sanibel' at Delray Beach, 'Equinox' at Fort
Pierce, 'Sanibel' and 'Sunbeam' at Homestead, and
'Sunbeam' at Quincy. 'Equinox' produced high yields
at three of the five locations. 'Sunbeam' produced
large fruit at four of the five locations and as did
'Sanibel' at three locations. Not all entries were grown
at each location.

Summary results listing the five highest
yielding and five largest fruited entries from trials at
the University of Florida's Gulf Coast Research and
Education Center, Bradenton; the Indian River

Table 1. Summary of University of Florida tomato variety
Variety Total Yield
Location (ctnfacre) Variety
Bradenton Suncrest 2728
Equinox 2460
BHN 22 2313
Florida 7786 2121
Floralina 20561


Research and Education Center, Ft. Pierce; and the
North Florida Research and Education Center,
Quincy for the fall 1998 season are shown in Table
2. High total yields and large fruit size were
produced by 'Florida 47' and 'Agriset 761' at Fort
Pierce and XPH 10035, 'Agriset 761', 'Sanibel', and
'Florida 47' at Quincy. 'Agriset 761', 'Equinox' and
'Florida 47' produced high yields at two of three
locations. 'Florida 47' and 'Sanibel' produced large
fruit at all locations. Again, not all entries were
included at all locations.

Overall, results of these trials indicate that
no single variety dominates the industry as during
the periods when 'Sunny' and 'Agriset 761' were
preeminent. Furthermore, varieties appear to be
more location and seasonal specific than in the past.



trials. Spring 1998 (1).


Size (oz)


BHN 22
Sunbeam
4413W
STM 5206
Equinox


Large Fruit
6.6
6.5
6.5
6.3
6.12


Delray Beach


Fort Pierce






Homestead


Sanibel
Suncrest
Agriset 775
Agriset 761
Sunpak (EX 10069)


Solimar
Florida 7786
Florida 7787
Equinox
Sunbeam


Sanibel
Equinox
EX 10090
PX 647095
Sunbeam


2979
2705
2680
2643
2632


2873
2803
2709
2576
25663


918
908
870
850
835s


Exp 10072 ESL
STM 5206
Sanibel
RFT 3260
Leading Lady
Florida 47


Sunbeam
Florida 7787
Equinox
Agriset 761
Solar Set
Florida 7763

Sanibel
Florida 91 (EX 10091)
Sunbeam
Florida 47
Florida 7791
Florida 7792


Quincy Sun Leaper 2172 BHN 102
BHN 444 2051 Sanibel
Sunbeam 2006 Sunbeam
SRT 6682 1826 Equinox
SRT 6685 1818' Sunpak (EX
'14 other entries had yields similar to Floralina.
214 other entries had fruit weight similar to Equinox.
33 other entries had yields similar to Sunbeam.
'2 other entries had fruit weight similar to Solar Set and Florida 7763.
55 other entries had yields similar to Sunbeam.
68 other entries had fruit weight similar to Sunbeam, Florida 47, Florida 7791, and Florida 7792.
718 other entries had yields similar to SRT 6685.


10069)


Size (oz)


VEGETARIAN NEWSLETTER


August 1999








Seed Sources:
Agrisales: Agriset 761, Agriset 775, Equinox.
Asgrow: Sunpak (EX 10069), EX 10072 ESL, EX 10090, Florida 91 (EX 10091), Florida 47, Solar Set, Solimar, Sunbeam.
BHN: BHN 22, BHN 102, BHN 444.
Novartis: Suncrest, Sun Leaper, RFT 3260, 4413W
Petoseed: Floralina, Sanibel, PX 647095
Sakata: STM 5206.
Sunseeds: Leading Lady, SRT 6682, SRT 6685.
University of Florida: Florida 7763, Florida 7786, Florida 7787, Florida 7791, Florida 7792.


Table 2. Summary of University of Florida tomato variety trial results. Fall 1998


Total Yield Large Fruit
Location Variety (ctn/acre) Variety Size (oz)

Bradenton PS 647095 1184 SRT 6629 6.8
Florida 7807 1162 Florida 91 (EX 10091) 6.6
Equinox 1135 Florida 47 6.5
Sun Leaper 1115 Sanibel 6.5
Floralina 10801 FT 6116 6.42

Fort Pierce Equinox 1120 Florida 47 5.6
Florida 7815 1087 Sanibel 5.6
Florida 47 1078 Agriset 761 5.4
Agriset 761 1071 Florida 7786 5.3
Solar Set 10523 Florida 7807 5.34

Quincy XPH 10035 1589 XPH 10035 6.2
Agriset 761 1559 Sanibel 6.0
Sanibel 1459 Florida 47 6.0
Florida 47 1447 Florida 91 (EX 10091) 5.9
Captiva 13955 Agriset 761 5.76

'13 other entries had yields similar to Floralina.
215 other entries had fruit weight similar to FT 6116.
'4 other entries had yields similar to Solar Set.
'4 other entries had fruit weight similar to Florida 7786.
s15 other entries had yields similar to Captiva.
68 other entries had fruit weight similar to Agriset 761.


Seed Sources:
Agrisales: Agriset 761, Equinox.
Asgrow: Florida 47, Solar Set, Florida 91 (EX 10091), XPH 10035.
Novartis: Sun Leaper, FT 6116
Petoseed: Captiva, Floralina, Sanibel, PS 647095.
Sunseeds: SRT 6629.
University of Florida: Florida 7786, Florida 7807, Florida 7815.

Tomato Varieties for Commercial
Production

The varieties listed have performed well in
University of Florida trials conducted in various
locations.

Large Fruited Varieties

Agriset 761. Midseason, determinate, jointed
hybrid. Fruit are deep globe and green shouldered.
Resistant: Verticillium wilt (race 1), Fusarium wilt
(race 1 and 2), Alternaria stem canker, gray leaf
spot (Agrisales).


BHN-444. Early-midseason maturity. Fruit are
globe shape and green shouldered. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race 1 and
2), and Tomato Spotted Wilt Virus. For Trial. (BHN).

Equinox. An early determinate, heat-tolerant jointed
hybrid. Fruit are flattened globe-shaped with uniform
green shoulders. Smoother blossom scar than
'Solar Set' enhances cool-season production.
Resistant: Verticillium wilt (race 1), Fusarium wilt
(race 1 and 2), and gray leaf spot. (Agrisales).

Florida 47. A late midseason, determinate, jointed
hybrid. Uniform green, globe-shaped fruit.
Resistant: Fusarium wilt (race 1 and 2), Verticillium


VEGETA"ANNEWMEIMdRZ


Augeust 199


(1).







VEGETARIAN NE WSLE


wilt (race 1), Alternaria stem canker, and gray leaf
spot. (Asgrow).

Floralina. A midseason, determinate, jointed hybrid.
Uniform, green shoulder, flattened, globe-shaped
fruit. Recommended for production on land infested
with Fusarium wilt, Race 3. Resistant: Fusarium wilt
(race 1, 2, and 3), Verticillium wilt (race 1), gray leaf
spot. (Petoseed).

Solar Set. An early, green-shouldered, jointed
hybrid. Determinate. Fruit set under high
temperatures (920F day/720 night) is superior to most
other commercial cultivars. Resistant: Fusarium wilt
(race 1 and 2), Verticillium wilt (race 1), Altemaria
stem canker, and gray leaf spot. (Asgrow).

Sanibel. A late-midseason, jointless, determinate
hybrid. Deep oblate shape fruit with a green
shoulder. Tolerant/resistant: Verticillium wilt (race 1),
Fusarium wilt (race 1 and 2), Alternaria stem canker,
root-knot nematode, and gray leaf spot. (Petoseed).

Solimar. A midseason hybrid producing globe-
shaped, green shouldered fruit. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race 1 and 2),
Alternaria stem canker, gray leaf spot: (Asgrow).

Sunbeam. Early midseason, deep-globe shaped
uniform green fruit are produced on determinate
vines. Resistant: Verticillium wilt (race 1), Fusarium
wilt (race 1 and race 2), gray leaf spot, Alternaria.
stem canker. (Asgrow).

Sun Leaper. A determinate, early midseason, heat-
tolerant hybrid. Fruit are uniform green and
flattened-globe to deep-oblate shaped. Resistant:
Verticillium wilt (race 1) and Fusarium wilt (race 1
and 2). (Novartis).

Sunpride. A midseason, tall determinate hybrid
producing deep globe to oblate-shaped, uniform
green fruit on a jointed pedicel. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race 1 and 2),
Altemaria stem canker, and gray leaf spot.
(Asgrow).

Plum Type Varieties

Marina. Medium to large vined determinate hybrid.
Rectangular, blocky, fruit may be harvested mature
green or red. Resistant: Verticillium wilt (race 1),
Fusarium wilt (race 1 and 2), Altemaria stem canker,
nematodes, gray leaf spot, and bacterial speck.
(Sakata).

Plum Dandy. Medium to large determinate plants.
Rectangular, blocky, defect-free fruit for fresh-


market production. When grown in hot, wet
conditions, it does not set fruit well and is susceptible
to bacterial spot. For winter and spring production in
Florida. Resistant: Verticillium wilt, Fusarium wilt
(race 1), early blight, and rain checking. (Harris
Moran).

Spectrum 882. Blocky, uniform-green shoulder fruit
are produced on medium-large determinate plants.
Resistant: Verticillium wilt (race 1), Fusarium wilt
(race 1 and 2), root-knot nematode, bacterial speck
(race 0), Altemaria stem canker, and gray leaf spot.
(Petoseed).

Supra. Determinate hybrid rectangular, blocky,
shaped fruit with uniform green shoulder. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race 1 and 2),
nematodes, and bacterial speck. (Novartis).

Veronica. Tall determinate hybrid. Smooth plum
type fruit are uniform ripening. Good performance in
all production seasons. Resistant: Verticillium wilt
(race 1), Fusarium wilt (race 1 and 2), Altemaria
stem canker, nematodes, gray leaf spot, and
bacterial speck. (Sakata).

Cherry Type Varieties

Mountain Belle. Vigorous, determinate type plants.
Fruit are round to slightly ovate with uniform green
shoulders borne on jointless pedicels. Resistant:
Fusarium wilt (race 1), Verticillium wilt (race 1). For
trial. (Novartis).

Cherry Grande. Large, globe-shaped, cherry-type
fruit are produced on medium-size determinate
plants. Resistant: Verticillium wilt (race 1), Fusarium
wilt (race 1), Alternaria stem blight, and gray leaf
spot. (Petoseed).

Reference

Maynard, D. N. (ed.). 1999. Vegetable variety trial
results in Florida for 1998. Fla. Agr. Expt. Sta.
Circ. S-396.

Tomato variety evaluations were conducted in 1998
by the following University of Florida faculty:


H. H. Bryan

T. K. Howe

S. M. Olson

J. W. Scott


Tropical Research & Education
Center Homestead
Gulf Coast Research & Education
Center Bradenton
North Florida Research & Education
Center Quincy
Gulf Coast Research & Education
Center Bradenton


August 1999


VECE~;eRIRNN~WS~:En;ER







VEGETARIAN NEWSLEI1ER Auxust 1999


K. D. Shuler Palm Beach Cooperative Extension
Service
P. J. Stoffella Indian River Research & Education
Center Fort Pierce

(Maynard, Olson, Vegetarian 99-08)


PHOSPHORUS AVAILABILITY AND RESPONSE
OF TOMATO TO PHOSPHOROUS FERTILIZER IN
CALCAREOUS SOILS

Calcareous soils that contain a large amount
of calcium carbonate (usually from 1-100% CaCO3
equivalent) are common in Florida because various
types of limestone underlie all of the peninsular.
Calcium carbonate can occur in the surface soils
naturally or as a result of land preparation (rock
plowing, bedding, etc.). Soils also can be calcareous
through over liming or long-term irrigation with calcium
carbonate enriched ground water. Calcareous soils
induce an array of nutritional problem for crops and
phosphorus (P) is one of them. Application of P
fertilizer is important for vegetable production on
calcareous soils. However, most growers apply too
much P fertilizer for their crops. Over-fertilization leads
to unnecessarily high production costs, may decrease
yield and quality and poses a risk to the environment.
In order to understand P chemistry and to make
fertilizer recommendation for calcareous soils in south
Florida, several laboratory and field experiments have
been conducted during 1997-1999.


A two-year field experiment was conducted in
a commercial vegetable field on a typical Krome very
gravelly loam soil in Miami-Dade County during 1997-
1998. Dry fertilizer was applied in 2 bands along the
top of the bed at three rates of P (37, 63, 100% of the
grower rate, equivalent to 96, 163, 260 lb P20, /Ac) in
1997 growing season and at four rates of P (0, 25, 50,
and 100% of the grower rate, equivalent to 0, 70, 140,
and 280 lb P20O/Ac) in 1998 growing season as triple
superphosphate with 6 replications. All of treatments
received same amounts of N and K as dry and liquid
fertilizers. "Sunbeam" tomato plants were transplanted
in a single row in the center of each bed with 20 inches
between plants. Tomatoes were harvested three times
at mature-green stage. Total number, total weight and
color of fruit from each plot were recorded. Soil and
leaf samples were also analyzed for P. The results
showed that phosphorous fertilization increased AB-
DTPA extractable P in the soil but did not affect the
concentration of leaf P, yield and quality of tomato with
the exception that the quantity of red fruit at the time of
first harvest, 1997 was increased slightly (Table 1).
Lamberts, O'Hair, Hochmuth, Hanlon and Bryan
(Research Report, 1999) also reported no response of
bean, Malanga, potato, and sweet corn to P fertilizer
during three years experiments on calcareous soils in
Miami-Dade County.


Table 1. Effects of P fertilizers on fruit yield and quality of tomato in 1997 and 1998.
Variable Fertilizer rate (Ib P20d/Ac)
1997 1998
96 163 260 0 70 140 280


Early yield (cartons/Ac)
Red
Green


54"b
541


215
425


64ab
524


Total yield (cartons/Ac)
Large fruit 406 393 436 695
Marketable 1474 1235 1403 959
Cull yield 210 195 226 151
Average fruit size (Ib) 0.37 0.36 0.37 0.34
'Each mean represents the average of 6 observations. Values followed by different letters are
according to Duncan's Multiple Range Test


Phosphorous removal via the harvested fruit
usually accounts for less than 38 Ib. P20 for 1000
cartons of tomato. A Large portion of the applied P
remains in the soil. It is important to know availability
of remaining P in calcareous soils. In 1998, surface
soil samples (0 6 inch depth) were collected from 6
typical vegetable fields in south Miami-Dade County.
Soil samples were extracted sequentially with water,
AB-DEPA, and the mixture of nitric acid and


188
427


152 108
448 458


750 752 809
947 998 988
188 168 134
0.36 0.35 0.35
significantly different from each other at p<0.05


hydrochloric acid to determine water soluble, plant
available and residual P in soils. Average
concentrations of water soluble P in soil samples
collected from various vegetable fields were 1.2 ppm
and ranged from 0.87 to 1.69 ppm (Fig. 1). Water
soluble P is available to the crop, however, this type
of P is also subject to leaching out of the root zone
through excessive irrigation or heavy rainfall.
Concentrations of AB-DTPA extractable P in these


VEGETARfAN NEWSLETTER


Ausust 1999






VEGETARIAN NEWSLETTER 7

soils ranged from 46.4 to 94.8 ppm with a mean F
concentration of 70.9 ppm. AB- DTPA extractable P
is plant available and highly correlated to the uptake
rate by the crop grown calcareous soils. Acid
extractable P in soils represents the P residue in
soils that is not directly available to plants. About 95
% of total P in 6 soil samples were in residual form.
Concentrations of residual P ranged from 1123.8 to
1877 ppm with a mean concentration of 1404.4 ppm.
Concentrated acids have to be used to extract this
type of P from soil. The level of residual P increases
with increasing age of cultivation of soils. Thus
phosphorous fertilizer applied to soils will transform
from water soluble to AB-DTPA extractable P and
eventually a portion of this P becomes residual form.
However, these chemical reactions are reversible.
Depletion of extractable soil P usually causes the
dissolution of residual P. Therefore, both extractable
and residual P in the soil should be considered when
making fertilizer recommendations.

Phosphorous fertilizers applied in calcareous
soils are fixed through adsorption and precipitation.
In 1999, we conducted a P sorption and desorption
experiment with 24 soil samples collected from
natural lands, vegetable fields and tropical fruit
groves. Adsorption was dominated reaction at low P
concentrations and P precipitated with calcium
carbonate at high P concentrations (Fig. 2).
Maximum sorption capacity for natural pineland soils
ranged from 4200 to 5600 ppm while Krome very
gravelly soils from vegetable fields only sorbed 690-
1700 ppm. It indicates that soils from vegetable
fields were saturated with P and excessive P applied
as fertilizer often precipitate and become less
available to crops. Desorption rate from vegetable
soils are higher than that from natural soils because
of high initial soil p in these soils (Fig. 3).

In summary, large amounts of P are
accumulated in most of cultivated calcareous soils
from fertilizer application. No P fertilizer application
is necessary for calcareous soils with high available
P levels. Grower should conduct pre-fertilizer soil
analysis to determine supplemental P fertilizer rates.


August 1999


(Yuncong Li, Vegetarian 99-08)


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8 August 1999


Vegetable Gardening



Florida's Largest Pumpkin

Florida is not known for its pumpkins, except
maybe calabazas. A lot are sold around Halloween,
but these are trucked in from other states. The
summer months just prior to Halloween are just too
hot and humid for prime pumpkin growing, resulting
in lots of fruit rots on the vines.

A good local retail produce store could sell
from 5000 to 6000 pounds of the round, orange type
in the week leading up to Halloween. But that is only
about 300 pumpkins at an average size of 20
pounds each. Put another way, that would only
amount to about 10 of the largest pumpkins ever
grown in our state.

Nationwide, we have been far outdone in the
search for the great pumpkin. The world record is
now over 1000 Ibs, and our Florida record is a mere
half that. When I started keeping records on Florida's
largest vegetables in 1989, our first entry in the
pumpkin category was a puny 200 pounder grown at
Keystone Heights.

In just ten years we have seen our state
record more than double, thanks to the efforts of
gardener Tim Canniff of Bradenton. In 1996, Tim set
a new record of 459 pounds. Every year since, Tim
has been planting seeds saved from this big Atlantic
Giant, trying to reach the 500 pound mark. Well,
1999 was almost his year.


Without giving away too many of Tim's
secrets, here are a few. First, this year he obtained
seed from an Atlantic Giant of 937 pounds grown up
north. Then he made sure to plant them precisely on
Valentine's Day, February 14, 1999.

A month later, the big vines spreading over
his tiny 450 sq ft garden were blooming, so on March
7, he self-pollinated the big female blossoms from
the male blossoms.

By mid-May, the giant orange blob had
reached a girth of over 100 inches. He tried to keep
the vines disease-free and growing by spraying a
fungicide and found that it helped. By June, the
pumpkin had reached gigantic proportions, and he
could wait no longer.

On June 5, 1999, Tim cut his 120 inch round
gargantuan and weighed it in at a whopping 494.5
pounds! While you did not quite reach your personal
goal, Tim, we'll give you 500! Congratulations, and
thanks for offering to share seeds from your orange
monster with anyone wanting to try to break your
record. Come on gardeners, take up Tim's challenge
in the new millennium.

(Stephens, Vegetarian 99-08)


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Prepared by Extension Vegetable Crops Specialists


Dr. D. J. Cantliffe
Chairman


Dr. T. E. Crocker
Professor


Dr. G. J. Hochmuth
Professor


Dr. D. N. Maynard
Professor


Dr. S. M. Olson
Professor


Dr. ofesorgent
Professor


Dr. W. M. Stall
Professor


Mr. J. M. Stephens
Professor


Dr. C. S. Vavrina
Assoc. Professor


552-39^- ~j Z


VEGETARIAN NEWSLETTER


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