The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
9a a j
Gulf Coast Research
and Education Center
5007 60th St. E., Bradenton, Florida 34203-9324
9 Institute of Food and Agricultural Sciences
E. University of Florida
PART II STRAWBERRIES AND VEGETABLE CROPS RESEARCH AND DEVELOPMENTS FOR 1991
PLANT BREEDING, GENETICS, AND CULTIVAR EVALUATION Page
Strawberry Breeding and Genetics ......................... 12
Tomato Breeding and Genetics ............................ 13
Vegetable Cultivar Evaluation ............................ 14
Specialty Vegetable Evaluation ........................... 17
BIOLOGICAL, CHEMICAL AND MECHANICAL PEST MANAGEMENT DEVELOPMENT
IN THE AREAS OF ENTOMOLOGY, PLANT PATHOLOGY, AND WEED SCIENCE
Entomology Strawberries ............................... 19
Entomology Vegetables ................................. 19
Plant Pathology Strawberries ........................... 21
Plant Pathology Vegetables ............................ 21
Virology ............................................. 24
Weed Science .......................................... 25
PRODUCTION, CULTURE, MANAGEMENT AND ENVIRONMENTAL CROP STRESS
Strawberries ........................................... 26
Vegetable Crops ......................................... 27
WATER MANAGEMENT AND NATURAL RESOURCE PROTECTION
Strawberries .................. ............................ 28
Vegetables and Other Crops .............................. 29
Strawberries and Vegetables .................. ..........
ORNAMENTAL CROPS RESEARCH AND DEVELOPMENT FOR 1991
I. Plant Breeding, Genetics, and Cultivar Evaluation of Ornamental Crops
A. Breeding & Genetics
Cultivar evaluation, genetics, and breeding was an integral part of
the ornamental program at GCREC during 1991.
1. Gladiolus G. J. Wilfret.
Over 50 cultivars and/or numbered seedlings were evaluated
from growers throughout the U.S. in the All-American Trial
Gardens. Of these, only 2 or 3 showed promise as a cut flower
for Florida, with the majority being more for shows or home
gardens. Many showed symptoms of Fusarium or virus and would
do poorly when grown in Florida. Breeding efforts were
centered on incorporating the fusarium tolerance of 'Dr.
Magie' into other colors and flower sizes', using pollen
parents with useful characteristics as spike length, floret
number, flower size, and individual floret design. Stock of
two cultivars, which were in replicated trials, indicated that
#470 (Orange) and #1298 (Rose w/red throat) should be released
when stock is increased.
2. Caladium G. J. Wilfret.
Evaluation of advanced seedling lines led to the release of 3
cultivars to industry. These were: 'Florida Elise' (pink),
'Florida Fantasy' (white w/red veins), and 'Florida
Sweetheart' (rose lance, will be patented). Genetic studies
on inheritance of foliar characteristics showed that red and
white spots are co-dominant alleles, that red veins are
dominant to green veins, and white veins are dominant to both
red and green, and that the homozygous red genotype is
epistatic to the white netted venation. Replicated trials
indicated that #117 (pink and white blotches), #215 (red
lance), and #214 (green lance) should be released in the near
future. Further hybridization will not only develop new color
combinations and leaf shapes but will elucidate inheritance of
blotching and petiole color.
3.. Poinsettia G. J. Wilfret.
Over 30 cultivars and/or seedlings were evaluated in the
glasshouse and shadehouse, and one, 'Freedom', showed great
promise for Florida. This has dark-green foliage with bright
red bracts and is marketable 7 weeks after initiation of short
B. Cultivar Evaluation
1. Petunia T. K. Howe and W. E. Waters.
Fifty eight cultivars were evaluated in a replicated field
trial with 77 additional cultivars evaluated in an
observational (single plot) field trial during the spring.
Subsequently, fifty nine cultivars were evaluated in a
replicated field trial with 69 additional cultigens evaluated
in an observational field trial during the fall. Plants were
grown in full sun in raised, mulched beds of EauGallie fine
sand. Irrigation was provided by subsurface seepage. For the
spring replicated trial, the range of time from sowing to the
first flower was 54 to 73 days. Plant heights ranged from 15
to 40 cm. Red flowered types were the shortest, while blue
and white types the tallest. Flower diameter ranged from 5.3
to 10.0 cm with grandiflora types 2.5 cm larger than
multiflora types. Spray damage to flowers was absent in all
blue and white colors as well as 'Supercascade Red' and
'Falcon Pink'. For the fall replicated trial, the range of
time from sowing to flowering was 52 to 76 days. Plant
heights were similar to the spring. Flower diameter ranged
from 5.1 to 10.2 cm, with grandifloras 2.0 cm larger than
multiflora types. Lodge resistance was related to plant
height, which was strongly linked to flower color. Generally
red flowered types lodged slightly if at all. Full results
have been published in the Florida State Horticulture Society
Proceedings and in a GCREC Research Report.
2. Assorted Flowering Bedding Plants T. K. Howe and W. E.
Two hundred twenty nine cultigens in the spring and 268
cultigens in the fall from commercial sources were evaluated
in field demonstration plots. Plants were raised in mulched
beds of EauGallie fine sand in full sun with sub-surface
seepage irrigation. Data taken included: date of first
flower, plant habit, plant dimensions, flower size and color,
subjective rating and presence of pests. These trials served
to introduce new cultivars to growers, extension service
personnel, landscapers and allied horticultural industries as
well as to provide a background of information on which to
base future evaluation work. Results have been published in
a GCREC Research Report.
II. Biological, Chemical and Mechanical Pest Management Development in
Ornamental Crops in the Areas of Entomology, Plant Pathology, and Weed
A. Plant Pathology
1. Phvtophthora A. W. Engelhard.
Phytophthora nicotiana var. parasitica causes serious disease
problems on petunias, snapdragons, vincas, poinsettias and
other plants. An isolate from snapdragon was very virulent on
snapdragon and vinca, mildly on pansy and avirulent on
petunia. A petunia isolate was very virulent on petunia,
snapdragon and mildly on vinca and pansy. An isolate from
vinca was very virulent on vinca but not on snapdragon,
petunia or pansy.
2. Chemical Control of Phvtophthora A. W. Engelhard.
Chemical control of Phytophthora by drenching with Sudue
metaloxyl 2E was excellent on petunia, snapdragon and vinca.
Truban etriazole did not control Phytophthora on petunia and
snapdragon but was effective on vinca. Aliette as a drench
provided good disease control on snapdragon and vinca but poor
on petunia. Aliette as a foliage spray (re the label)
generally did not control Phytophthora on any crop. Banol
provided little or no control on petunia and snapdragon.
Captan 50W was intermediate in control on all 3 crops.
3. Pythium A. W. Engelhard.
Pythium myriotylum causes root rot on carnation, petunia, and
verbena. Among compounds labelled for disease control, Truban
etridiazole gave excellent disease control on all 3 crops.
Subdue metalaxyl 2E, a widely used soil fungicide gave only
moderate control, while Aliette 80WP at label rates both as a
drench or foilage spray gave poor control on all three crops.
The same Pythium isolate was used on all 3 crops. This
illustrates how chemicals for disease control can be used and
losses can still be extensive. The species and origin of a
pathogen appears to be important.
4. The Challenge A. W. Engelhard.
The above mentioned compounds are all labelled and generally
recommended for pythiaceous fungi such as Pythium and
Phvtophthora, yet the use of recommended fungicides can result
in serious losses to the producer because the chemicals are
not effective on a specific crop or pathogen species. In
reality, we have costs associated with purchasing the
fungicides plus the plant losses resulting from applying
ineffective but recommended and labelled fungicides.
5. Chrysanthemum A. W. Engelhard.
Ninety-nine cultivars of chrysanthemums were evaluated for
susceptibility to infection by Didymella li ulicola (Ascochvta
chrysanthemi). Many cultivars had a high tolerance to the
pathogen and would require little or no spraying. Ascochyta
blight control again was obtained with tank mixes of a
systemic and a non-systemic fungicide, each at one-half rate.
Banner propiconazole, Benlate benomyl DF and Chipco Iprodione
26019 in combination with captain, Daconil chlorothalonil, or
mancozeb gave good control. Plants tended to be somewhat
shorter with the Banner mixtures.
B. Weed Science
1. Registration of Pennant for Weed Control in Gladiolus J. P.
Research was conducted at the GCREC and with a commercial
grower to identify herbicides which might replace Lasso.
Experiments, spring and fall, established that Pennant
provides safe, efficacious control of most of the same weeds
which Lasso controls. Several other herbicides demonstrated
some potential, but Pennant appeared to perform the most
similar to Lasso and the manufacturer was willing to work
quickly with the industry to expand the Pennant label to
2. Clover Control in Saran House Grown Cut Flower Crops J. P.
Field experiments conducted at a commercial farm over the past
two years have identified Ronstar as the safest, most
efficacious herbicide for sweet clover control in many
floricultural crops. As a result of this research, the
industry has begun using Ronstar on a trial basis and the
manufacturer is determining whether label expansion is
required or economically feasible. Unfortunately, snapdragons
are very sensitive to Ronstar and represent a major crop in
saran house production. Therefore, additional studies are
underway to determine if below normal rates will provide
clover control and reduce the amount of damage suffered by
snapdragons. To date, it appears that a one-eighth X rate
provides excellent control for at least 30 days and produces
near acceptable damage. Delayed planting also is being
investigated as a means of obtaining additional safety.
1. Sweetpotato Whitefly Research J. F. Price.
a. Azadirachtin from Neem Seeds. Azadirachtin from heem
seeds, when applied at 30 ppm weekly for 5 weeks,
controlled an outbreak of sweetpotato whitefly, under
simulated greenhouse conditions.
b. Several insecticides were evaluated for their effects on
egg, young nymph, old nymph, pupa and adult sweetpotato
whitefly lifestages. Candidate pesticides were
identified that could be useful to control sweetpotato
whitefly in poinsettia and other ornamental crops.
c. Nymphal sweetpotato whiteflies move less than 2 mm on
poinsettia, resulting in more complicated control and
little likelihood of infesting neighboring plants.
Movement was greater on squash than on poinsettia.
d. Exclusion of Sweetpotato Whitefly from Production Areas.
Evelen woven fabrics were tested to find the largest
woven opening that would prevent a male or a female
sweetpotato whitefly from penetrating. Use of fans in
a production area affect the size of openings required.
III. Production, Culture, Management and Environmental Stress of Ornamental
A. Nutrition, Production, and Environmental Factors
1. Pontederia cordata Temperature Requirements B.K. Harbaugh
and M.E. Kane.
a. Temperature requirements for production of Pontederia
cordata, a native wetland plant valued for wetland
mitigation and aquatic landscaping, had not been
reported in the literature. Pontederia growth was
determined to be optimal at 77 to 820F. Regression
analyses indicated leaf number, plant height and plant
fresh weight would be less for plants grown at
temperatures above or below this range.
b. Nutritional guidelines for production of Pontederia
cordata are lacking. When compared on a kg/m- basis,
plants grown with Osmocote 17-6-12 had more leaves and
greater fresh weight than plants grown with 14-14-14 or
12-10-17 formulations. When comparisons were made as g
N/pot, growth was similar indicating formulations with
the highest N would be the most economical to use.
Additional studies indicated a ratio of 1N:0.1P:0.4K
would provide adequate P and K for Pontederia
production. Using this ratio, 50 ml of an 800 ppm N
solution applied once a week for two weeks and then
twice a week for six weeks produced plants with greatest
fresh weight and plant quality.
2. Lisianthus Rosetting B. K.Harbaugh.
As temperature increased above 770F, the percentage of
lisianthus seedlings which rosetted increased, with nearly
100% rosetted plants at 82 and 880F. Age of seedling did not
effect percentage of rosetted plants, but the percentage of
rosetted plants ranged from 0% to 100% depending on cultivar.
Cultivars least sensitive to high temperature exposure were
breeding lines selected at GCREC for heat tolerance.
3. Eustoma grandiflorum Stunting B. K. Harbaugh.
Foliar chlorosis or bleaching, interveinal chlorosis, leaf
edge and tip necrosis, a poor root system, and stunted growth
of Eustoma grandiflorum seedlings were associated with a
medium pH of 5.0 or 5.5 but not when the values ranged from
6.4 to 7.5. The range in medium pH resulting in the best
growth of seedlings and flowering plants was 6.3 to 7.5.
Eustoma seedling fresh weights were only 23% to 66% of
corresponding values for plants grown at pH 6.4. Leaf tissue
Zn was extremely high (1050 mg/kg dry leaf tissue) at a medium
pH of 5.0, but other macro- and micronutrients in leaves were
not at abnormal levels.
4. Eustoma grandiflorum Selections B. K. Harbaugh and J. W.
Over 200 lines of commercial and GCREC Eustoma grandiflorum
selections were evaluated for heat tolerance. Of these lines,
all of the commercial lines had greater 90% rosetted plants
after exposure to high temperatures. Five GCREC blue
selections, in the fourth and fifth generation from the
initial heat tolerant selections, were tolerant to high
temperatures with 90 to 100% flowering after seedlings were
exposed to high temperatures. These same lines were evaluated
in Beltsville, Maryland with similar promising results as
releases for breeding lines for heat tolerance. [In
cooperation with D. Rubino (USDA)].
5. Pentas lanceolata Studies B. K. Harbaugh.
Preliminary investigations indicated severe microelement
imbalances were induced in Pentas lanceolata grown in soil
with a low soil pH. Imbalances were not corrected with soluble
micro elements, but addition of limining materials to the
soil, or correction with soluble lime, resulted in diminished
6. Ornamental Tomato Breeding B. K. Harbaugh and J.W. Scott.
Over 50 advanced lines of gold fruited miniature ornamental
tomatoes were evaluated in spring and fall tests. Final
evaluations should be made this year for a release as
excellent lines with bright gold fruit, good tomato flavor,
improved leaf appearance and retention, and plant size
comparable to 'Micro-Tom' were selected which were consistent
for these desirable characteristics in both seasons.
B. Control of Growth and Development of Ornamental Crop Species
1. Caladium Studies M. R. Evans and B. K. Harbaugh.
Caladium growth and development after exposure of tubers to
ethylene and high temperatures Exposure of tubers to 1 to 10
ppm ethylene did not effect subsequent growth and development.
Exposure to temperatures above 31C (88 F) for 3 days resulted
in a delay in shoot emergence and subsequent poor growth.
Exposure of tubers, either as dry tubers or as potted tubers,
to 43C (1100F) for as little as 16 hours per day for 4
consecutive days completely inhibited shoot growth. These
results indicate, despite caladium being a tropical species,
the importance of controlling temperatures during tuber
shipment and during forcing of potted caladiums.
2. Caladium De-eying M. R. Evans and B. K. Harbaugh.
Effect of method and time of de-eyeing on growth and
development of caladium Time (before or after curing and
storage) and method (increasing severity) of de-eyeing was
studied in a 2-year project. The time of de-eyeing had no
effect on subsequent development of plants. As the severity of
the de-eyeing treatment increased, the crop variability
increased and the quality decreased. The optimal method of de-
eyeing was determined to be removal of the dominant terminal
bud without removing any of the starchy portion of the tuber.
3. Liatris spicata Studies M. R. Evans and B. K. Harbaugh.
Control of growth and development of Liatris spicata The
factors involved in the development of flowering shoots were
studied to increase the number of flowering shoots formed per
tuber, to increase the portion of the flower spike bearing
flowers and to develop dwarf liatris types for potted plant
production. Removal of the central dominant bud resulted in a
three-fold increase in the number of flowering shoots produced
per tuber. Research was conduct that indicated that the
dominant shoot exerts correlative control over the secondary
shoots and inhibits flowering. Five dwarf types of L. spicata
were selected and evaluated for potential as potted types.
Additional research was conducted on the role of mineral
nutrition vernalization and photoperiod on flower spike
4. Specialty Cut Flowers M. R. Evans.
Development of new species for production as ornamental crops
Twenty-eight species were evaluated as potential new cut
flower species for production in Florida. Additionally, 5
species were studied as potential potted crops. These potted
crops were selected for study based on potential ornamental
value as well as their dwarf habit which would allow for
production without the use of growth retarding chemicals.
5. Growth Regulators G. J. Wilfret.
PGR's were applied to poinsettia, Easter lilies, and
chrysanthemums to determine the optimum chemical rate and
spray volume. Optimum rates of ancymidol on poinsettias
ranged from 0.25 to 0.375 mg ai/pot as a soil drench, of
paclobutrazol ranged from 30 to 60 ppm as a foliar spray, and
of uniconazole ranged from 5 to 10 ppm. Easter lily
treatments were best with soil drenches of ancymidol,
paclobutrazol, and uniconazole at ranges of 0.25-0.5 mg ai,
3.0-4.0 mg ai, and 0.0625-0.125 mg ai, respectively.
Applications of single and/or multiple applications of
paclobutrazol and/or uniconazole showed that the former PGR
needed to be sprayed at 100 ppm while the latter was effective
at 10 ppm. Spray volumes of 3 qts/100 ft2 were more effective
than 2 qts/100 ft2 with both chemicals.
C. Plant Physiology and Nutrition
1. Plant Physiology S. S. Woltz.
A very destructive disease of Eustoma grandiflorum (Raf.)
Shinn. (Lisianthus) has been encountered regularly in Florida
for a number of years. The condition is best described as a
crown root rot apparently incited by Fusarium solani (Mart.)
Appel & Wright. In normal culture in the field and greenhouse
there has been a variable incidence of the disease occurring
in a relatively random manner. Fusarium solani was isolated
repeatedly from affected plants. The isolates were effective
in producing the symptoms when inoculated onto Eustoma
seedlings and cuttings. The Fusarium was recovered following
inoculation. Greenhouse experiments were conducted to gain
information about the influence of lime, nitrogen sources, and
NaCl on the incidence and severity of the disease. The
disease was aggravated by the use of low (1 kg per cubic
meter) as compared to higher (5 kg per cubic meter) rates of
CaCO3 as a liming material in a 1:1 Canadian peat:vermiculite
mix. Ammonium sulfate as a N source was associated with
greater disease than was Ca(N03). Plant quality was
adversely affected (noninoculated controls) by these
conditions that also favor disease. Supplemental applications
of NAC1 did not alter the severity of the crown and root rot.
Disease developed slowly after inoculation and continued to
develop for a period of time.
2. Fusarium Crown Rot Control S. S. Woltz.
Control of tomato Fusarium crown rot (F. oxvsporum f. sp.
radicis-lycopersici) was obtained consistently with CaCO3, but
not with CaSO4 amendments to a 1:1 mix of Canadian
peat:vermiculite. Control was due to increased pH of the mix,
not to increased calcium. Micronutrients added to nonlimed
mix greatly increased disease development. Moreover, EDTA-
micronutrient complexes added to limed mix reversed the
beneficial effects of liming and increased the severity of
STRAWBERRIES AND VEGETABLE CROPS RESEARCH AND DEVELOPMENTS FOR 1991
I. Plant Breeding, Genetics, and Cultivar Evaluation
A. Strawberry Breeding and Genetics
1. Propagation of FL 85-4925 Strawberry C. K. Chandler.
Approximately 15,000 runner tips of FL 85-4925 were rooted in
polystyrene trays during the spring of 1991 and distributed to
cooperating nurseries. FL 85-4925 offers strawberry growers
and shippers in west central Florida a short-day cultivar that
is early fruiting and produces fruit with excellent flavor.
Plants of FL 85-4925 from northern latitude nurseries are 2 to
3 weeks earlier fruiting than 'Oso Grande', a University of
California release, which is currently the major short-day
cultivar being grown in west central Florida. This
characteristic could make FL 85-4925 particularly useful to
west central Florida growers because, in their situation, the
timing of fruit production is often more important than the
total amount of fruit harvested.
2. Strawberry hybridization and selection C. K. Chandler.
Numerous hybridizations and selections were made for the
purpose of developing useful strawberry clones for Florida,
and for expanding the knowledge of strawberry genetics. The
following steps were taken:
a. Intercrossed 50 clones.
b. Identified desirable families and parents from a block
of seedlings derived from a factorial set of crosses.
c. Selected cultivar candidates from among a population of
d. Determined which of 100 selections should be advanced to
the replicated trial.
e. Compared 13 advanced selections to 3 standard cultivars
and 3 new cultivars and decided which selections should
be placed in grower trials.
f. Grew 16 seedling populations under field conditions
ideal for the development of anthracnose crown rot.
Recorded mortality in these populations. This data will
be used to help determine the heritability of crown rot
3. Interaction between strawberry genotypes and planting date -
C. K. Chandler and E. E. Albregts.
Container-grown transplants of 'Dover', 'Oso Grande', 'Selva',
FL 83-37, FL 85-4925, and FL 87-210 strawberry were set at
AREC-Dover on raised beds in early, mid, and/or late Oct.
1990. The early set plants produced a greater number of
runners than did the mid or late set plants. The influence of
planting date on early season (Nov., Dec., and Jan.) fruit
production varied with genotype. 'Dover' produced its highest
early season fruit yield when planted late, while 'Oso Grande'
and FL 85-4925 produced their highest early season fruit yield
when planted early. For 'Selva', FL 83-37, and FL 87-210,
planting date did not affect total early season fruit yields.
B. Tomato Breeding and Genetics
1. Rough Blossom Scar Studies J. W. Scott.
Studies on rough blossom scar, a major cause of cull tomato
production, were completed. This work established a
foundation of knowledge of this heretofore little understood
disorder. A short term cold treatment (6 days at 18/100C) was
found to cause roughness in flowers 19-25 days before anthesis
at the time of treatment. This treatment can be used for
screening work or as a basis to do other studies on
fundamental causes of rough scars. Also the inheritance of
blossom scar size has been determined. Furthermore, several
distinct blossom-end morphology genes were characterized by
allelism tests which can be used in breeding for resistance to
2. Tomato Mottle Geminivirus J. W. Scott.
Genes for resistance to the sweetpotato whitefly vectored
Tomato Mottle Geminivirus are being introgressed from 8
Lycopersicon chilense accessions. Many F BC, plants have now
been obtained by embryo rescue from which we hope to obtain
complete resistance to this threat to the Florida tomato
3. Tomato Heat Tolerance Studies J. W. Scott.
Considerable selection and testing of heat tolerant tomatoes
continued. Emphasis is being, placed on combining heat
tolerance with tolerance to bacterial wilt or bacterial spot.
Heat tolerant inbreds with improved fruit size and blossom
scar smoothness have been developed. Of note is Fla. 7324
which has been used as a parent in experimental hybrids which
have performed well in state wide yield trials. Heat
tolerant, bacterial wilt tolerant Fla. 7421 has shown promise
for several years and will likely be released as an open-
pollinated variety. Several heat tolerant, bacterial spot
tolerant inbreds have performed well over several seasons and
some may be released in the not too distant future.
4. Tomato Breeding Race 3 Resistance J. W. Scott.
Breeding for resistance to Fusarium wilt race 3 and Fusarium
crown rot resistance continued. Several race 3 inbreds, some
with jointless stems appear promising and should be close to
the release stage as breeding lines. Fusarium crown rot lines
need a little more fruit size. Crosses were made to address
5. Other projects included; breeding for improved shelf life with
the ripening inhibitor (rin) gene, developing male-sterile
inbreds using the ms-10 gene linked to prx-2 or a marker
genes, studying the role of volatiles in tomato flavor,
developing improved jointless tomato breeding lines,
developing gold-fruited miniature-dwarf tomato lines, breeding
for resistance to the sweetpotato whitefly, and breeding
parthenocarpic (seedless) tomato lines adapted to Florida
conditions. Most of these projects are progressing, but will
not result in releases for a few years yet. The exception may
be with the gold-fruited, miniature-dwarf program. If seed
production problems have been overcome by our most recent
selections, a release could be made in 1993.
C. Vegetable Cultivar Evaluation
1. Cabbage T. K. Howe and W. E. Waters.
Thirty cultivars of cabbage were examined in a replicated
field trial at GCREC during the winter of 1990-91. Subjective
evaluations characterized head shape, density and other
attributes. Overall appearance ratings of good (G) to very
good (VG) included thirteen entries. Those superior due to
density and lack of defects were: (alphabetically by source)
'Solid Blue 770', 'Solid Blue 780', 'Cheers', 'Green Cup', 57-
460, 'Tempo', 'Krautman', HMX 7271, 'Izalco', 'Fortuna', PSR
21288, 'Blue Vantage' and 'Royal Vantage'. Of these, 'Tempo',
'Green Cup', 'Krautman', 'Solid Blue 780', 'Blue Vantage' and
'Royal Vantage' were also rated superior in the 1989-90
production season, and 'Krautman', 'Fortuna', 'Blue Vantage',
and 'Green Cup' were rated well during 1988-89. Six entries
(XPH 5781, XPH 5783, XPH 5785, 'Gourmet', 'Olympic' and PSR
86384) were rated poor based on such factors as poor density,
presence of internal tip burn, bursting and attributes not
acceptable for commercial use.
Yields, based on the percentage of marketable heads cut versus
the number of plants set, ranged from 49% for 'Krautman' to
95% for 'Solid Blue 780'. Three cultivars, 'Solid Blue 780',
'Olympic' and 'Cheers', exceeded 90% marketable yield. Yield
by weight ranged from 504 crates/A for 'Gourmet' to 1156
crates/A for 'Cheers'. Four other cultivars, 'Solid Blue 780'
(1152 crates/A), 'Tempo' (1123), 'Olympic' (1048) and 'Rio
Verde' (992), were not significantly different from 'Cheers'
2. Cherry Tomato T. K. Howe and W. E. Waters.
A replicated cherry tomato trial was conducted in the fall of
1991 to compare 2 commercially available cultivars to an IFAS
bacterial spot resistant breeding line. Seasonal yields after
six harvests were 4380 flats/A for 'Cherry Grande', 3179
flats/A'for 'Mountain Belle' and 2565 flats/A for IFAS 7333.
Seasonal average individual fruit weights were 0.8, 0.7 and
0.5 oz respectively. IFAS 7333 produced no yield until the
second of the six harvests and peaked at the sixth. It became
comparable in yield to the greatest yield at the fourth
3. Cucumber (Slicing) T. K. Howe and W. E. Waters.
Twenty cultigens of slicing cucumber were examined in a
replicated yield at GCREC during the fall of 1991. Early
yields from the first 2 of 12 harvests ranged from 45 bu/A for
HSR 183 to 337 bu/A for 'Maximore 103'. Three other entries
were not significantly different in yield than 'Maximore 103',
they were: FMX 4761, 'Raider' and HSR 181. U.S. Fancy fruit
yield ranged from 19 bu/A for HSR 183 to 150 bu/A for
'Maximore 103'. Nine other entries were similar to 'Maximore
103' early in U.S. Fancy yield, they were: FMX 4761,
'Raider', HSR 181, 'Maximore 100' 'General Lee', 'Dasher II',
'Speedway', 'Prolific', and HMX 6402. Total seasonal yields
ranged from 977 bu/A for Sunre 3720 to 1516 bu/A for FMX 4761.
Fourteen entries were not significantly different than FMX
4761 in total yield for the season. Total seasonal U.S. Fancy
fruit yield ranged from 402 bu/A for 'Slice Max' to 609 bu/A
for 'General Lee'. There were no significant differences in
total seasonal U.S. Fancy yields among the cultigens.
'Prolific', HMX 6402, 'Speedway' and Sunre 3720 each produced
over 60% of their total marketable yields as U.S. Fancy fruit.
4. Pepper (Bell) T. K. Howe and W. E. Waters.
Spring 91. Thirty-two cultigens of sweet bell pepper were
evaluated in replicated trial at the mature green stage during
the spring of 1991. In addition, twelve cultigens were
harvested for yield estimates from single, unreplicated plots.
Seasonal yields of the replicated trial for three harvests
ranged from 417 cartons/A for 'Zico' to 1053 cartons/A for
'Verdel.' Sixteen other entries were not significantly
different in yield as compared to 'Verdel.' Yields were
reduced due to pepper weevil late in the season. The number
of marketable fruit per plant ranged from 1.7 for P-1288 to
4.3 for 'Crispy.' Eight entries were similar to 'Crispy' in
the total number of marketable fruit per plant. Average fruit
weight for the season of 7.0 oz or greater was produced by
eight entries; 'Verdel,' 'King Arthur,' 'Ssupersweet 860,' PR
300-2, PSX 3187, PR 89-3, PSX 72286 and 'Galaxy.' The
proportion of harvested fruit which were culled ranged from
19% for PSX 3187 to 41% for 'Empressa.' Twenty-one other
entries were not significantly different than PSX 3187 in
total cull fruit produced. Cull fruit were separated for sun-
scald damage and for symptoms of mosaic virus damage. Sun-
scald damage for the season did not exceed 9% of the total
harvest for any entry. Virus-like damage was greatest for NS
43504 and 'Bell King' at 8% and 4% of the total harvest,
respectively. Entries with very little to no observable
bacterial leaf spot symptoms (rated as light) were: 'Rebell'
(formerly XPH 5693), 'Crispy,' 'Bellguard,' NS 411, NS 412,
8076, 9139, 'Park's Early Thickset,' PR 89-3, PR 300-1, PR
300-2, PR 300-6, PR 300-7, 'Gator Belle,' 'King Arthur,' PSR
14890, PSR 49587, PSX 3187, PSX 37786, and PSX 88888.
Fall 1991. Twenty-four cultivars and breeding lines of sweet
bell pepper were evaluated in replicated trial at the green
stage during the fall of 1991. In addition, twelve cultigens
were harvested for yield estimates from single, unreplicated
plots. Seasonal yields of the replicated trial for four
harvests ranged from 272 cartons/A for 'Pek Bell' to 1086
cartons/A for 'King Arthur'. Thirteen other entries were not
significantly different than 'King Arthur'. Armyworm
infestations reduced yields, bacterial spot was not a factor.
The number of marketable fruit per plant ranged from 1.7 for
'Pek Bell' to 6.9 for 'King Arthur'. Twelve entries were
similar to 'King Arthur' in the number of marketable fruit per
plant. Average fruit weight for the season of 4.7 oz or
greater, to a high of 5.1 oz, was produced by thirteen
entries. Worm damaged fruit at harvest was between 27 and 55%
among the entries. Above stated yields were adjusted to
ignore this specific damage. However, many fruit aborted
before harvest due to worm damage. Virus-like fruit damage
was greatest for 'Pek Bell', FMX 1154 and 'Bell King' at 28%,
28% and 11% of total harvested fruit, respectively.
5. Tomato T. K. Howe and W. E. Waters.
Spring 91. Replicated and observational fresh market tomato
trials were conducted in the spring of 1991 to assess various
commercial cultivars and breeding lines and IFAS breeding
lines. There were 20 replicated entries which were harvested
for yield comparisons and 72 observational entries which were
not harvested. Quantitative results from the replicated trial
follows: Total marketable yields after two harvests for the
spring ranged from 1251 cartons/A for IFAS 7384 to 2195
cartons/A for XPH 5796. These yields are much lower (30-40%
less) than those achieved at this location in recent spring
seasons. The bacterial spot infection and presence of the
Florida Tomato Geminivirus were the main reasons for the low
yields. Ten entries were not significantly different than XPH
5796 in yield, they were: IFAS 7385, 'Solar Set', IFAS 7308,
IFAS 7307, 'Agriset 761', IFAS 7264, PSR 864189, 'Sunny',
'Cobia' and PSR 853689. Extra-large fruit yield ranged from
a low of 644 cartons/A for 'Regency' to 1239 cartons/A for
'Solar Set'. Eight other entries were similar to 'Solar Set'
in extra-large fruit yield, they were: 'Merced', IFAS 7385,
PSR 864189, IFAS 7264, 'Agriset 761', 'Sunbeam', 'Cobia' and
IFAS 7306. Large fruit ranged from 340 cartons/A for IFAS
7384 to 863 cartons/A for IFAS 7308. Only three other entries
were not significantly different than IFAS 7308 in large fruit
yield, they were: XPH 5796, IFAS 7307 and IFAS 7385. Average
fruit weight of 6 oz or greater was produced by 'Merced' (6.5
oz), IFAS 7306 (6.2), IFAS 7384 (6.1), 'Cobia' (6.0), PSR
853689 (6.0) and 'Sunbeam' (6.0). The proportion of total
fruit harvested which were culls ranged from 17% for IFAS 7307
to 44% for 'Regency'. Seven entries were below 25% in cull
Fall 91. Replicated and observational fresh market tomato
trials were conducted in the fall of 1991 to assess various
commercial cultivars and breeding lines and IFAS breeding
lines. There were 17 replicated entries which were harvested
and 60 observational entries which were not harvested.
Quantitative results from the replicated trial follows: Total
marketable yields after three harvests for the fall ranged
from 584 cartons/A for 'Colonial' to 1702 cartons/A for IFAS
7430. Nine other entries were not significantly different
than IFAS 7430 in yield, they were: IFAS 7249B, IFAS 7264,
'Merced', 'Heatwave', IFAS 7427, NVH 4466, IFAS 7375, 'Solar
Set' and IFAS 7267. Yield of extra-large fruit ranged from
153 cartons/A for 'Colonial' to 619 cartons/A for IFAS 7430.
Eleven other entries were similar to IFAS 7430 in yield of
extra-large fruit. They were: IFAS 7264, 'Merced', IFAS 7427,
'Heatwave', IFAS 7249B, NVH 4466, 'Solar Set', IFAS 7267, XPH
5796, 'Tango' and 'Sunbeam'. Average individual fruit weight
ranged from 4.8 oz for 'Sunny' and IFAS 7375 to 5.6 oz for
'Tango'. Two cultigens, IFAS 7430 and IFAS 7249B, produced
less than 20% of total fruit as culls.
D. Specialty Vegetable Evaluation
Specialty vegetables are a diverse group that include those
vegetables grown on small acreages (formerly called minor crops),
ethnic vegetables, gourmet vegetables, and miniature vegetables.
Production of specialty vegetables offers the opportunity of
diversification for large growers and production of high-value crops
by small growers that permit them to be competitive in the market
1. Spinach Variety Evaluation D. N. Maynard.
A replicated trial of three smooth-leaf varieties, four semi-
savoy-leaf varieties, and nine savoy-leaf varieties was
conducted in the winter 1991 season. Yields ranged from 142
and 148 bu. per acre for 'Vienna' and 'Marathon' to 201 and
222 for 'Hybrid 612' and 'A&C #30', respectively. Other high
yielding varieties were 'Gladiator', 'Tyre', 'A&C #19',
'Chinook II', 'A&C #10', 'Ambassador', and 'Skookum'.
2. Cantaloupe Cultigen Evaluation D. N. Maynard.
Replicated trials of 24 hybrids were conducted in the spring
of 1991 to identify those having high quality and yields of
western-type fruit. Varieties that combined high yield and
had fully netted fruit with slight or no sutures were
'Pronto', 'Solid Golid', 'Challenger', 'Cruiser', 'Tasty
Sweet', 'Hymark', 'Valley Gold', and 'Hiline'.
3. Icebox-Type Watermelon Cultigen Evaluation D. N. Maynard.
Replicated trials of 8 icebox entries were conducted in the
spring 1991 season. Total marketable yields ranged from 354
cwt/A for 'Sugar Baby' to 523 cwt/A for 'Baby Gray', however,
they were not statistically different from each other.
Average fruit weight for the entire season varied from 6.5 lb
for 'Minilee' to 9.9 lb for 'Exp. 1185' (Rogers NK). Average
fruit weights of 'Baby Gray', 'Mickylee', and 'Sugar Baby'
were similar to that of 'Minilee'. Soluble solids ranged from
10.6% for Exp. 1184 (Rogers NK) and 'Sugar Baby' to 12.2% for
S89J39-1 (CFREC). High soluble solids were also obtained in
Exp. 1185 (Rogers NK), 'Baby Gray' and 'Minilee'.
4. Triploid Watermelon Cultiqen Evaluation D. N. Maynard.
Replicated trials of 27 entries were conducted in spring 1991.
Total yields ranged from 261 cwt/A for CFREC 89-4 to 546 cwt/A
for 'Ssupersweet 5032'. Eighteen other entries had total
yields similar to those of CFREC 89-4 whereas 23 other entries
had total yields similar to those of 'Ssupersweet 5032'.
Average fruit weight for the entire season varied from 8.4 lb
for NVH 4296 to 12.9 lb for 'Ssupersweet 5032' and
'Ssupersweet 5344'. The average fruit weight of 13 other
entries was similar to that of NVH 4296 whereas 14 other
entries had average fruit weight similar to those of
'Ssupersweet 5032' and 'Ssupersweet 5344'. Fruit soluble
solids were uniformly high ranging from 11.1% for
'Millionaire' to 12.9% for SWM 8702.
5. Calabaza Cultigen Evaluation D. N. Maynard.
Seven entries were evaluated in the fall 1991 season. Highest
yields were produced by 'La Primera' and 'La Segunda'.
Intermediate yields were produced by the Puerto Rican entries
'Borinquen', Soler, and Linea C Pinta. Lowest yields were
from CFREC bush types L18-4 and L-26-3. Flowering and
fruiting was latest in the Puerto Rican entries.
6. Asparagus Variety Evaluation D. N. Maynard.
Eight entries were established from 1-year old crowns in a
replicated feasibility study in February 1991.
II. Biological, Chemical and Mechanical Pest Management Development in the
Areas of Entomology, Plant Pathology, and Weed Science
A. Entomology Strawberries
1. Establishment of Biological Control of Twospotted Spider Mite
on a Commercial Farm J. F. Price and M. Van De Vrie.
Release of the predatory mite, Phytoseiulus persimilis at an
early stage of spider mite population development resulted in
maintenance of spider mites below economically damaging
levels, provided no hazardous pesticides were applied.
2. Dispersal of Phytoseiulus persimilis, Predator of Twospotted
Spider Mite J. F. Price and M. Van De Vrie.
Dispersal of this predator, under field conditions, is
performed by early stage immature forms carried by air
3. Stability of the Predator/Prey System J. F. Price and M. Van
When P. persimilis has reduced the spider mite prey population
to non-damaging levels, a balance is established between
spider mite and P. persimilis predators, and naturally
occurring predators such as, Scymnus sp., lacewing larvae and
predatory midge larvae.
4. Strawberry Cultivar Effects on the Twospotted Spider Mite J.
Rate of spider mite reproduction and development and sex ratio
of spider mite offspring were not variously affected by leaves
of numerous strawberry cultivars. Spider mite populations
among plants of those cultivars may be affected, however, by
variations in leaf area.
5. Influence of Insecticides on P. persimilis under Field
Conditions J. F. Price.
Malathion and diazinon, used at recommended rates on
strawberries caused some mortality in the mobile stages of P.
persimilis, however, the population was able to recover
because the eggs were unaffected. Motile form P. persimilis
are killed by certain formulations of captain but not by the 50
B. Entomology Vegetable
1. Encarsia perqandiella D. J. Schuster.
More adult Encarsia perqandiella, a parasite of the
sweetpotato whitefly (SPWF), were captured on yellow sticky
traps than on traps of other colors. However, the percent
response of the parasite to color traps was less than that of
the SPWF. Fewer male SPWF adults responded than did females
and more adult SPWF and parasitoid adults were captured on
sticky traps without plants than with plants.
2. Parasitic Wasps Studies D. J. Schuster.
A two year survey of parasitic wasps attacking the SPWF in
Florida was completed. Three species of parasitic wasps
(Encarsia niqricephala, E. pergandiella and Eretmocerus
californicus) were reared consistently from SPWF nymphs
collected on 30 different plant species throughout southern
Florida. Parasitism on three weed hosts Primrose Willow
(Ludwiqia spp.), Hairy Indigo (Indiqofera sp.) and Spurge
(Chamaesyce spp.) near commercial tomato fields was high
during the summer and fall of 1991 reaching >90%. The survey
data suggested that there may be a shift in seasonal abundance
of some of the parasitoids on some host plants and possibly a
seasonal displacement of one species by another.
3. E. perqandiella Study D. J. Schuster.
The first visual evidence of parasitization of whitefly nymphs
by E. perqandiella was migration of the whitefly mycetomes at
about 6-7 days after oviposition by the parasitoid. The egg
to adult developmental period of females was about 16 days on
bean and poinsettia but about 17 days on tomato. Males are
produced as hyperparasitoids of females.
4. Lvcopersicon pennelli Study D. J. Schuster.
Resistance to the SPWF in Lycopersicon pennellii and L.
hirsutum was confirmed in the greenhouse and laboratory and
appeared to be related to density and stickiness of glandular
trichomes on leaves.
5. Weekly trapping in the Hillsborough and Manatee County
production area has indicated that winter crops, especially
cabbage and potatoes, can.carry the SPWF from the fall tomato
crop to the spring crop. Furthermore, early planted tomatoes,
particularly cherry tomatoes, can carry the SPWF vectored
geminivirus from the fall to the spring crops.
6. Plastic Soil Mulch Color Study D. J. Schuster.
Plastic soil mulch painted aluminum, yellow or orange resulted
in fewer immatures of the SPWF and delayed symptoms of
geminivirus on tomato compared to white plastic mulch.
Applying vegetable oil to the yellow mulch resulted in fewer
adults and delayed virus relative to the mulch without oil.
7. Sweetpotato Whitefly Vegetable Attraction D. J. Schuster.
Eggplant and squash were more attractive to the SPWF compared
to bean and okra in the laboratory although no crop appeared
more attractive than tomato. More whitefly adults were
observed on foliage of squash and okra relative to the other
plant species early in the season in the field. Percent
parasitism in the field was highest on eggplant.
8. Crop Oil Studies D. J. Schuster.
Of four crop oils evaluated in the field, one resulted in
fewer tomato plants infected with SPWF transmitted geminivirus
compared to a check.
9. Endosulfan Study D. J. Schuster.
A decline in the susceptibility of the SPWF to endosulfan was
detected in commercial tomatoes despite rotations among
classes of insecticides by growers.
10. Insecticide Evaluation for Control of Sweetpotato Whitefly -
D. J. Schuster.
At least 20 insecticides or insecticide combinations,
including registered and experimental products, were evaluated
in field trials on tomato for control of the SPWF, armyworms
C. Plant Pathology Strawberries
1. A comprehensive article by Charles M. Howard, John L. Maas,
Craig K. Chandler and Earl E. Albregts, "Anthracnose of
strawberry caused by the Colletotrichum complex in Florida" is
being published as a feature article with color plates in the
Plant Disease Journal. This is an excellent summary article
on the disease, its history, organisms involved,
dissemination, symptoms, and controls.
D. Plant Pathology Vegetables
1. Fusarium Crown Rot J. P. Jones and S. S. Woltz.
a. Nitrate-nitrogen, compared to ammonium-nitrogen,
alleviated Fusarium crown rot, caused by F. oxvsporum f.
sp. radicis-lvcopersici, in the field. However, an
increase in soil pH only slightly inhibited crown rot
b. Control of crown rot with calcium carbonate was
determined to be due to increased soil pH, not to
increased calcium. Micronutrients added to nonlimed
soil greatly increased disease development and EDTA-
micronutrient complexes added to a limed potting mix
reversed the beneficial effects of liming and increased
disease incidence, indicating that crown rot control by
liming was due to an imbalance in the micronutrient diet
of the pathogen or host.
c. A streptomyces biocontrol agent did not affect Fusarium
crown rot development in a growth room study.
2. Fusarium Wilt J. P. Jones and S. S. Woltz.
Fusarium wilt of tomato caused by E. oxvsporum f. sp.
yvcopersici race 1, 2, or 3 was found to be greatly reduced
and yield losses totally eliminated after a fallow period of
3. Fusarium Wilt Resistance J. P. Jones and S. S. Woltz.
Tomato cultivars with monogenic resistance to Fusarium wilt
were not ultra-susceptible to races for which they had no
4. ELISA Disease Assay J. B. Jones, G. C. Somodi and H. Bouzar.
Direct plating and immunofluorescence techniques to
differentiate bacterial spot-resistant from susceptible tomato
genoytpes are effective but not efficient on a large scale.
Therefore, considerable effort was spent developing an ELISA
assay that detects Xanthomonas campestris pv. vesicatoria
(XCV) at concentrations of less than 10 cells in leaf tissue
which enables the rapid and accurate screening for resistant
genotypes. Previous ELISA methods detected 10 10 cells
without leaf tissue. The effective method involves macerating
leaf tissue and allowing cells to soak overnight in an EDTA-
lysozyme solution prior to running the ELISA procedure. A new
rinse was also developed that helped increase the sensitivity
of the assay. The procedure enables the detection of low
bacterial populations, and thereby resistant genotypes. In
two experiments, direct plating and immunofluorescence
techniques were compared to the ELISA method. Correlations
were highly significant between all methods, indicating that
the new ELISA technique has great potential.
5. Bacterial Spot of Tomato Screening (Conventional) J. B.
Jones, G. C. Somodi and J. W. Scott.
In a summer experiment, parent lines and F2s were tested by
preconditioned seedling screens and by placing the same plants
in the field and subsequently rating them to see how
accurately the seedling screen was in predicting field
performance. Seedling screen ratings were significantly
correlated with both the first and second field ratings.
Where screening ratings were greater than 6%, 90% of the
plants in the field were rated susceptible. It seems that
plants with high disease ratings can be withdrawn from the
testing in the seedling screening stage based on these
6. Bacterial Wilt (Pseudomonas solanacearum) Studies of Tomato -
J. B. Jones, G. C. Somodi and J. W. Scott.
A summer experiment compared several inoculum concentrations
on wounded or unwounded resistant and susceptible genotypes,
as well as planting inoculated plants adjacent to uninoculated
plants to determine which method would provide the most
effective bacterial wilt screen under field conditions in
southwest Florida. Plants were rated weekly over a period of
several) months. In this test, inoculum concentrations of 108
and 10 were equally effective on wounded or unwounded plants
although appearance of symptoms and death of plants was more
gradual with 10 Adjacent treatments took too long to show
symptoms. In a previous test, 10 had been noticeably better
than 10 The variation in results prompted greenhouse and
growth room studies on soil moisture and soil temperature to
determine their effect on bacterial wilt development.
7. Pectate+/Starch+ XCV Strains Isolated at GCREC J. B. Jones,
H. Bouzar, and G. C. Somodi.
Bacterial spot symptoms were noted on the resistant tomato
genotype H7998. Isolations were made and the strains were
studied. Strains of XCV in Florida have historically been
Pectate-/Starch-. Strains were tested by a starch test,
pectate test, Hr test and ELISA. Of approximately 50 strains,
nearly half were Starch+/Pectate+ obtained primarily from
GCREC fields planted to genotypes resistant to the FL XCV
strain. Cooperators in Gainesville showed that these strains
were not South American type strains (they are Pec+/Starch+
also) but were different than typical FL strains.
8. South American Strains of XCV J. B. Jones and H. Bouzar.
These strains were differentiated from Florida strains by
protein profile patterns. Thus, there appear to be unique
regions which may serve as possible antigens for serological
differentiation between these two types of strains. These
strains also were discriminated by reaction patterns on a
panel of 95 different carbon sources and with a group of
monoclonal antibodies. Thus, there appear to be at least two
very distinct populations of XCV in the world.
9. Florida Strains of XCV J. B. Jones and H. Bouzar.
The genetic region necessary for expression of two epitopes
associated with lipopolysaccharide of a Florida strain of XCV
was identified. A 4.5 to 5.5 kb region was essential for
expression. Probing with DNA from this region revealed that
it reacted most strongly with strains of XCV. Primers made to
a 680 bp region reacted with all Florida strains (12) but
with only 1 of 12 South American strains. This region may
prove useful for detection of XCV.
1. Establishment of a Functioning Plant Virology Laboratory at
GCREC J. E. Polston.
A laboratory and several small greenhouses were outfitted with
equipment and supplies to carry on research directed to virus
identification, detection, virus-vector interactions and
virus-host plant interaction.
2. Probe Detection of Geminivirus J. E. Polston and E. Hiebert.
In cooperation with E. Hiebert, molecular virologist at
Gainesville, a probe system was developed for detecting
geminiviruses. A rapid assay/probe system was developed which
could identify any whitefly-transmitted geminivirus and could
also separately identify TMoV from the other geminiviruses in
weeds and crop plants in Florida.
3. Establishment of a Host Range of the Tomato Mottle Geminivirus
by Whitefly Transmission J. E. Polston.
Twenty to forty whiteflies acquired virus from infected tomato
and were then placed on test hosts. Infections were confirmed
using nucleic acid spot hybridization with a virus specific
probe. A wide range of host plants were tested representing
7 plant families, 19 genera and 31 species. This virus is a
Solanaceae specialist, infecting only one test plant species,
Phaseolus vulgaris, outside that family.
4. Transmission Characteristics of the Tomato Mottle Geminivirus
J. E. Polston.
Research on the transmission characteristics of the tomato
mottle geminivirus were initiated. It was determined that
whitefly immatures could not acquire the virus. Other studies
are in progress.
5. Epidemiology Study J. E. Polston.
A multi-season epidemiology experiment was initiated on the
distribution and movement of the tomato mottle geminivirus.
A preliminary experiment was conducted in the fall season of
1991 which was designed to generate data which would be used
to establish a larger experiment to begin in spring season of
1992. From the fall season data, it was determined that the
number of samples which had to be collected to confirm visual
estimates, and was able to estimate the number of traps that
would be necessary to use to correlate virus incidence and
6. Overseasoning J. E. Polston.
The identification of overseasoning sources of the tomato
mottle geminivirus were initiated. Volunteer tomatoes were
found in July and August in pastures and in weeds surrounding
spring fields. Of the volunteers collected and assayed,
approximately 35% tested positive for TMoGV. This strongly
suggests that volunteer tomatoes can serve as overseasoning
sources of the virus.
7. Tomato Viruses Study J. E. Polston.
A preliminary survey of viruses in tomatoes in the Ruskin area
was conducted in the spring season, 1991. Approximately 80
samples were assayed by ELISA and nucleic acid spot
hybridization assay for six viruses. It was found that there
were a number of viruses present in tomatoes besides the
geminivirus. Viruses that were detected were transmitted by
aphids, whiteflies and thrips. The most prevalent viruses
were PVY and TMoGV. Tomato spotted wilt virus (TSWV) was
detected in plants without characteristic symptoms associated
with TSWV and at a higher rate than expected. Many plants
were assayed in which more than one virus was detected. Other
viruses detected in addition to those previously mentioned
were tobacco etch virus. A significant percent of the samples
which displayed virus-like symptoms tested negative for the
viruses assayed; This suggests the presence of at least one
8. TMoGV Resistant Tomato Germplasm J. E. Polston, J. W. Scott
and D. J. Schuster.
Assayed breeding lines for presence of the virus, using
nucleic acid spot hybridization assay and a virus specific
probe. Ways to inoculate large numbers of tomato seedlings
with virus before they are placed in the field were studied.
9. Pepper Viruses J. E. Polston, D. N. Maynard and M. Bassett.
Research on pepper viruses in Jamaica was initiated as part of
the M.S. degree requirements of Don McGlashan. The topic of
his thesis is to 1) identify the viruses infecting Scotch
Bonnet pepper in Jamaica and 2) to determine which of these is
causing the greatest impact on yield. This will lead into a
dissertation to develop resistance in pepper to that virus.
E. Weed Science
1. Purple Nutsedge J. P. Gilreath.
Competition of purple nutsedge with tomato. Competitive
aspects of nutsedge have been researched by many in the past;
however, the effect of nutsedge in a mulched bed on tomato
yield has not been determined. Current grower philosophy is
that nutsedge growing through the polyethylene film competes
with the crop and control is attempted with herbicides,
sometimes with disastrous results. This preliminary research
suggests that nutsedge in the bed does not affect yield
2. Photodegradation of Paraquat J. P. Gilreath.
Phytotoxicity of residual paraquat on polyethylene mulch film
to tomatoes. Previous research demonstrated that the
photodegradation rate of paraquat under field conditions is
much slower than earlier literature indicated. This explained
grower stand losses which heretofore were inexplicable. It
also suggests that the common practice of using paraquat to
burn back nutsedge growing through the mulch film may not be
entirely safe. Research was conducted to quantify yield
effects when transplants were exposed to residual paraquat.
Yield losses approaching 50% were not uncommon. This
reinforces the previous work and demonstrates the importance
of preventing contact of young plants with paraquat residues
for several days after application.
III. Production, Culture, Management and Environmental Crop Stress
1. Pre-Plant Drip Fertilizer Study E. E. Albregts, C. D.
Stanley, and G. A.Clark.
A 3 year study demonstrated that the application of pre-plant
fertilizer whether banded or broadcast did not affect fruit
quality or yield as long as fertilization through drip system
began within a few days of transplanting. Cooperators Drs.
Stanley and Clark.
2. Strawberry Foliage Removal E. E. Albregts.
In a 4 year study it was demonstrated that partial or total
removal of foliage of transplants from local or Canadian
sources delays and/or reduces early fruit yields. With local
plant sources total fruit yields can be reduced and plant
mortality can be increased by foliage removal.
3. Nitrogen Rates E. E. Albregts.
Strawberry fruit yields and quality were similar with 200 Ibs
N/acre from Oxamide alone or in combination with urea (3:1
ratio), or with methylene urea (3:1 and 1:1 ratios), methylene
urea alone, sulfur coated urea alone and with a 1:1 ratio of
both sulfur coated urea and NH4NO3, IBDU alone and a 1:1 ratio
of IBDU and urea.
4. Drip Irrigation/Fertilizer Rates E. E. Albregts.
Rates of 0.50, 0.75, 1.00, and 1.50 Ibs/acre/day of N and K
were applied weekly to drip irrigated Selva and FL-79-1126
strawberry. For N and K rates of 0.50, 0.75, 1.00, and 1.50
Ibs/acre/day, yields for Selva in 1000 Ibs/acre were 19.6,
24.5, 22.7, and 19.8 and for FL-79-1126 were 23.3, 22.6, 23.0,
and 21.1, respectively. Average fruit weight varied little
with fertilizer rates within each cultivar. Leaf N and K were
adequate on sampling dates of 1/24/91 and 4/2/91.
5. Recorded Extension Requests E. E. Albregts and C. K.
265 visits or requests were recorded from growers and other
agricultural related personnel for assistance from the Center
during the 1991 season. Soil diagnostic service was provided
on approximately 100 soil samples for 45 growers and 726
diagnostic culture plates were made for 90 growers by
Biological Scientist Alicia Whidden with response assistance
by faculty. This does not include many unrecorded walk-in
visits or faculty field visits.
B. Vegetable Crops
1. Colored Mulch Study A. A. Csizinszky.
In the spring, yellow colored mulch with an oil overspray and
aluminum painted mulch resulted in better fruit size and
larger marketable yields of 'Sunny' tomato than black
(control), orange, orange with oil overspray, and yellow
(without oil overspray) treatments. Gemini virus (averaged
over all mulch color treatments) reduced the yield of extra
large tomatoes by 35% and total marketable yield by 24%.
2. Slow-Release Fertilizer Study A. A. Csizinszky.
'Jupiter' bell peppers on plastic mulched beds produced
significantly higher early and total marketable yields with
increased fruit size when 50% of the N and 50% of the K was
derived from a slow-release fertilizer source. The seasonal
yield (per 1000 linear bed feet) of US Fancy grade fruit was
709 lb with the 50% slow release and 338 lb with the soluble
N + K source. Marketable yields for the season were 3640 lb
with the 50% slow release and 2939 lb with the soluble N + K
3. Methylene Urea Study A. A. Csizinszky.
In the fall gemini virus symptom development in 'Solarset'
tomato was delayed at 3 Ibs of N and 6 Ibs of K,0/100 linear
bed feet nutrient rate vs 2 N and 4 K20 lb/100 IbT. Methylene
urea at 50% or 75% of the total N, also delayed geminivirus
symptom development. Overall, slow release N combinations had
no yield advantage over 100% soluble N-sources under full bed
IV. Water Management and Natural Resource Protection
1. Water Requirements and Crop Coefficients of Microirrigated
Strawberries G. A. Clark, E. E. Albregts and C. D. Stanley.
Water balance lysimeters at the Dover AREC were used to
measure the water requirements of fruiting strawberry plants.
Studies were performed over.the 1988/89, 1989/90, and 1990/91
crop seasons. Seasonal crop water use averaged 270 mm.
Weather data was electronically logged to determine daily
values of Penman reference evapotranspiration (ETo). Crop
coefficients determined as the ratio of crop water use to
evaporative demand (ETo) ranged from 0.34 during early growth
to 0.79 at peak growth and development.
2. Management and Scheduling of Microirrigated Strawberries G.
A. Clark, E. E. Albregts and C. D. Stanley.
Field plots located at the Dover AREC were used to evaluate
the effects of three moisture management levels as irrigation
scheduling thresholds for microirrigated strawberries over the
1988/89, 1989/90, and 1990/91 crop seasons. Switching
tensiometers were set at -15, -10, and -5 cb and were wired
into the irrigation controller. Resultant irrigation
applications of 150, 180, and 270 mm, respectively, did not
affect fruit quality or yield.
3. Alternative Sprinklers for Establishment of Strawberries G.
A. Clark, E. E. Albregts and C. D. Stanley.
An alternative sprinkler design using lower output sprinklers
for establishment of strawberry transplants was tested during
the 1991 fall season at the Dover AREC. The alternative
system results in lowered irrigation application uniformity
and lower establishment application amounts (120 mm vs. 250
mm) with no differences in early yield or early dry matter
production as compared to conventional sprinkler applications.
4. Fertilizer Application Rates Study on Strawberries E. E.
Albregts and G. A. Clark.
A study to determine the effects of application rates and
formulation of fertilizer (injected liquid or dry) for
microirrigated fruiting strawberry production resulted in no
significant differences for either rate (160 kg ha"' N was the
low rate) or for preplant dry fertilizer versus injected
B. Vegetables and Other Crops
1. Water Requirements and Crop Coefficients of Microirrigated
Tomatoes G. A. Clark, C. D. Stanley and A. A. Csizinszky.
Water balance lysimeters installed at the Gulf Coast REC were
used to measure the water requirements of fresh market, staked
tomato plants. The study was initiated in the fall of 1989
and encompassed three spring crops and two fall crops ending
with the spring 1992 season. Daily weather data were used to
calculate Penman reference evapotranspiration (ETo) and crop
water use coefficients (kc). Spring season plant water use
averaged 200 mm while fall season plant water use averaged 130
mm. These values do not include water evaporated from the row
middles which will be included at the end of the project.
2. Fully Enclosed Subirriqation (FES) for Tomato Production in
Southwest Florida G. A. Clark and C. D. Stanley.
A method of subirrigation for field crops has been developed
which uses commercially available drip irrigation tubing as a
water conveyance system for subirrigation purposes. Drip
tubes positioned on 6 m centers in a field cropped with a
sorghum cover at the Gulf Coast REC were operated from between
10 and 24 hours per day to provide a water table within 18 to
24 inches of the ground surface. Tubing burial tests were
conducted to determine the effects of burial on system
operation. Tubes placed on the ground surface, at 15 cm
depths and at 40 cm depths all performed similarly with no
adverse effects of burial on tubing performance.
3. Scheduling and Management of Microirrigated Watermelon D. N.
Maynard and G. A. Clark.
Three levels of irrigation management were used to determine
the effects of moisture surplus and deficit levels on yield
and quality of microirrigated watermelon in field plots at the
Gulf Coast REC. Rainfall during the spring 1991 season was
higher than normal and affected the deficit irrigation
treatment. Initial indications showed no differences in yield
or fruit quality among the moisture management levels.
4. Water Deficit Studies on Microirrigated Tomato G. A. Clark,
C. D. Stanley, and D. N. Maynard.
Microirrigated tomato field plots are being used to determine
the effects of deficit irrigation levels on yield and quality
of marketable fruit. Adequate irrigation level plots are
scheduled based upon a switching tensiometer set at -10 cb.
Four deficit treatments will receive 15, 30, and 45 percent
less water, and no additional water throughout the growing
season following a 2 week establishment period. This study is
currently in progress.
5. Water Table Management Level Effects on Production of Fresh
Market Tomatoes and Bell Peppers C. D. Stanley and G. A.
A three year study has been initiated to determine the effects
of water table position on yield and quality of fresh market
tomatoes and bell peppers as well as the effects on leaching
of applied fertilizer to the shallow groundwater table. Three
water table management levels will be managed using the fully
enclosed subirrigation (FES) system in field plots located at
the Gulf Coast REC. Tomatoes will be grown during spring
production seasons and bell peppers will be grown during fall
production seasons using standard recommendations for
fertilizer as well as two elevated levels. This study is
currently in progress.
6. Economic Analysis Return-Risk Study J. W. Prevatt, G. A.
Clark and C. D. Stanley.
An economic analysis of the return-risk aspects of adopting
microirrigation versus seepage subirrigation showed that
microirrigation assumes more risk than seepage and only with
use of double cropping can higher expected returns result.
7. Fertilizer Movement and Plant Uptake C. D. Stanley and G. A.
A study to determine whether fertilizer movement and plant
uptake is affected by the timing of injected fertilizer
application (at beginning of irrigation cycle, 25% into cycle,
50% into cycle, or 75% into cycle) for microirrigated tomato
production showed no significant difference among treatments
indicating that if water is managed to prevent leaching beyond
the root zone, then the cycle timing of application is not
8. Automated Control of Water Table Depths G. A. Clark and C.
Preliminary investigations on automated control of water table
depths using the fully-enclosed seepage system (using float
switch control) showed water applications of 1.0-1.3 times the
pan evaporation rate were needed to maintain water table
levels at desired positions.
9. Greenhouse Tomato Growth Model C. D. Stanley and B. L.
Work was initiated to collect base data to adapt a greenhouse
tomato growth model (developed by Dr. J. Jones, Agric. Engin.)
to field conditions for use in nutrient budgeting and water
quality investigations. Similar work for crop parameters for
a citrus growth model using EPIC was also initiated.
10. The Manatee Watershed
and G. A. Clark.
Demonstration Project C. D. Stanley
Installation of improved management practices for vegetable
and citrus production was initiated on cooperating growers
fields as part of the Lake Manatee Watershed Demonstration
Project. Baseline data continues to be collected as more
sites are added to the study.
IV. Agricultural Economics Strawberries and Vegetables
Dr. J. Walter Prevatt, Agricultural Economics
completed three significant industry economics
resignation, May 1991. They are listed below:
reports prior to his
"Florida Strawberry Production Costs and Returns". 1991. GCREC Res. Rept.
"Return-risk Analysis of Adopting Drip Irrigation".
in Agriculture 8:47-52.
1992. Applied Eng.
"A Comparative Cost Analysis for Vegetable Irrigation Systems".
The information contained in this report is a summary of experimental results and
should not be used as recommendations for crop production. Where trade names are
used, no discrimination is intended and no endorsement is implied.