A Vegetable Crops Extension Publication
Vegetable Crops Department 1253 Fifield Hall Cainesville.F 32611 Telephone 392-2134
February 18, 1992
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
II. COMMERCIAL VEGETABLES
A. Phytotoxicity from Foliar Detergents Sprays.
B. National Symposium on Stand Establishment in
1 C. Looking for the Best Supersweet Sweet Corn.
S II. VEGETABLE GARDENING
A. 2 Effects of Variety on Sweet Potato Weevil.
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COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA.
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INSTITUTE OF FOOD AND
UNIVERSITY OF FLORIDA
UNIVERSITY OF FLORIDA 1
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
March 5-6, 1992. Postharvest
Horticulture Institute. University Centre
Hotel, Gainesville. (Contact Steve
March 9-12, 1992. Harvest and
Postharvest Handling of Horticultural
Crops. Tour of Central and South Florida.
(Contact Steve Sargent).
March 10, 1992. Cabbage variety
trial field day to evaluate 33 entries at
Central Florida REC, Sanford (10:00 AM-
Noon, contact J. M. White).
March 17, 1992. The annual USDA-
IFAS carrot hybrid trial will evaluate 54
experimental and named hybrids and 70
named or advanced entries in Zellwood.
Plots are on Zellwin Farms, take the main
road (Laughlin) on to the muck and follow
the signs (1:00 PM, contact J. M. White).
April 13-16, 1992. Joint Tomato
Quality Workshop and Tomato Breeders
Roundtable. Sarasota, FL. Contact Dr. J.
W. Scott, Gulf Coast REC for Tomato
Breeders Roundtable and Dr. Brecht,
Vegetable Crops Dept., UF, for Tomato
March 15-19, 1992. Second
International Symposium on Specialty and
Exotic Vegetable Crops. Miami (contact
November 16-20, 1992. National
Symposium for Stand Establishment in
Horticultural Crops. Sheraton Harbor
Place, Ft. Myers. (Contact Charles
Vavrina, SWFREC Immokalee).
I. COMMERCIAL VEGETABLES
A. Phytotoxicity from Foliar
The proven efficacy of detergents in
controlling Florida whiteflies (Stansly et.
al., SS-VEC-01) has fostered widespread
use despite information suggesting usage
can result in reduced plant weight (Vavrina
and Stansly, SS-VEC-01). Recent trials at
the SWFREC verify detergent sprays
reduce plant weight, and reduce and delay
yield in proportion to concentration and
frequency of application.
Preliminary studies in the summer
of 1991 indicated that detergent sprays
reduced plant weight. A follow-up study in
the fall of '91 was conducted to determine
the detergent effect on fresh market
tomato yield. "New Day" detergent (similar
to Tide) concentrations of 0.25%, 0.5%, 1%
and 2% were applied once or twice weekly,
beginning one week after planting and
continuing through week 10 of a tomato
crop. Application volumes ranged from 50
to 150 gallons per acre depending on crop
maturity; application pressures ranged
from 150 to 200 psi. Plant dry weight was
determined at two week intervals through
week 9 of the crop. Yield and grade were
assessed as a result of treatment.
Untreated plants had higher plant
weight throughout the sampling period,
weighing significantly more than all
detergent treated plants at week seven.
However, by week 9 the untreated plant
significantly out weighed only the 1% and
2% detergent treated plants. All
concentrations of detergent caused greater
plant weight reduction when sprayed twice
weekly as opposed to once.
The apparent reduction in growth
exhibited by the detergent treated plants
through the first 7 weeks in the field
resulted in a significant yield reduction at
first harvest (Figure 1). The increased
yield realized by the untreated plants
appeared to be a function of fruit size, as
plants not treated with detergent produced
more extra large fruit than detergent
treated plants at first harvest (Figure 2).
Again the reduction in yield and extra-
large tomatoes was heightened if detergent
was applied twice weekly.
Yields of detergent treated tomatoes
(especially low concentrations) tended to
compensate for early low yields at second
and third harvest. This suggests that
detergents tended to delay maturity except
where phytotoxicity was apparent (1% and
Combined data of all three harvests
showed that the untreated plants and
plants treated with the lower
concentrations of detergent (0.25% and
0.5%) yielded similarly (Figure 1).
Significant differences in-total yield existed
only between the untreated plants and the
1% and 2% detergent treated plants.
However, the disparity in yield of extra-
large tomatoes persisted between the
untreated and detergent treated plants
The effect of spray frequency was
also pronounced on the yield of extra-large
tomatoes. If sprayed twice a week, the
reduction extra-large tomato yield was
greater than if sprayed once a week,
regardless of detergent concentration.
Detergent concentrations presently
used by growers in the field (0.25%) appear
to be effective in controlling whiteflies and
causing little damage with respect to plant
weight loss and yield reduction. The
overall effect of spraying detergents at low
concentrations appears to be one of delayed
maturity rather than outright
phytotoxicity, as low rates generally
rebound from early weight loss and
produce yields similar to the untreated
plants. The use of low detergent
concentrations is warranted providing the
frequency of application is not excessive
enough to effect yield.
(Vavrina & Stansly, Vegetarian 92-02)
FIG. 1 DETERGENT EFFECTS ON TOMATO YIELD
HARVEST 1 TOTAL YIELD
0o 0IID 0.25% = 0.5%
S1% =lill 2%
FIG. 2 DETERGENT EFFECT ON X-LARGE YIELD
o 1 0o.25% EM 0.5%
B. National Symposium on
Stand Establishment in Horticultural
The third biennial National/
International Symposium on Stand
Establishment for Horticultural Crops will
be held November 16-20, 1992 in Ft.
Myers, FL at the Sheraton Harbor Place
Hotel. This symposium is presently co-
sponsored by the American Society for
Horticultural Science, the Florida Fresh
Fruit & Vegetable Association, the Florida
Seedsmen & Garden Supply Association,
and the Florida Tomato Committee.
Biotic and abiotic factors contribute
to successful stand establishment and
hence the optimization of crop production.
Such factors begin with the seed and effect
the crop through juvenility into early
maturity. This symposium is designed to
investigate this realm of factors and
endeavors to keep you current in the state
of the art of stand establishment.
Scientists from over 20 states and 6
countries have regularly attended.
Previous symposia have presented a
diverse selection of topics in three general
Seed seed enhancements, seed
coatings, seed moisture, vacuum
moisturization, matriconditioning, solid
matrix priming, priming with biological
control agents, seed storage and handling.
Transplants ebb & flow and
conventional transplant production,
transplant age and cell size, pruning,
nutrient conditioning, postharvest packing
and storage, transplanting technology
including automatic transplanting.
Field Establishment direct
seeding technology, gel seeding, soil
amendments, mulches, control of seedling
diseases (biological and otherwise), row
covers, cultural practices to improve stands,
nutritional and environmental effects on
The symposium will include invited
papers, contributed papers, posters,
industry booths, and field tours of
southwest Florida production areas and
transplant houses. Research scientists,
extension specialists, growers, and students
are encouraged to participate. For more
information on the symposium, contact:
Office of Conferences (ask for Monique),
551 IFAS/University of Florida,
Gainesville, FL 32611-0551 or call 904-392-
5930. Please Register Early.
(Vavrina, Vegetarian 92-02)
C. Looking for the Best
Supersweet Sweet Corn.
Each sweet corn grower and breeder
has his/hers ideas on the best sweet corn
to produce. In order to help everyone to
see and judge for themselves, a supersweet
(shrunken-2 gene) sweet corn variety trial
was conducted in the Zellwood area during
the spring of 1991. Planting by hand was
done on March 29 in plots 20 ft long using
9-inch in-row spacing. A randomized
complete block design was used for 76
entries in the replicated trial. Only first
ears were harvested and individual plots
were harvested once. The data collected
on each entry is presented in Research
Report SAN 91-01, August 1991. The real
value of the trial was the Field Day where
growers and seedsmen could go through
the plots and judge for themselves.
Unfortunately, there is no written record
of their comments that can be used
publicly. So, I will include only my
comments and opinions on the varieties
and lines which were the best during this
trial. Please remember, another season
and another set of growing conditions may
produce another "top 10."
Yield as measured in crates/acre
was not found to be significantly different
for the top 10 entries. Yield did range
from 332 to 269 crates/acre. Paksweet,
Challenger, ES-XP-35, XPH 2687,
Supersweet 8102, and Showcase had the
best overall horticultural characteristics of
the highest yielding 10 entries. Ear tip fill,
husk cover, ear appearance, ear length, ear
diameter, and ear shape were all
considered. It is encouraging to note that
two unnamed lines, ES-XP-35 from the
Everglades Research and Education Center
and XPH 2687 from Asgrow were in the
top entries. The "pipe line" has many lines
with potential. This year's variety trials
should showcase some of these and will be
of interest to growers who would like to see
the new material compared to their choices
of reliable varieties.
(White, Vegetarian 92-02)
III. VEGETABLE GARDENING
A. 2 Effects of Variety on Sweet
The following is a report by George
Henry (Leon County Extension Agent -
Agronomy) on a study he has been doing
for two years on the sweet potato weevil.
In the late 40's and 50's, almost
every farm family within Leon County was
engaged in sweet potato production to one
extent or another, as was the case
throughout the rural counties of Florida.
The sweetpotato weevil was prevalent as a
destructive pest, but was kept under
control by the use of DDT. Since the
banning of this insecticide, weevil
infestation has reduced the acreage in
Leon County to 35 acres or less.
In May 1990, George received and
planted for trial six cultivars from Dr. P. K.
Duke, USDA Vegetable Laboratory at
Charleston, SC. These cultivars were:
'Excel', 'Beauregard', 'Southern Delight',
'Sumor', and 'Regal'. The standard was
In his study, George evaluated the
following: sweetpotato weevil, flea beetle,
wire worm, cracking, soil rot, drought
resistance, and storage life.
In June 1991, the trial continued
but was amended to include only 'Southern
Delight', 'Beauregard', 'Regal', 'Excel', and
a new bunch-type cultivar numbered 'W-
Results and Comments
On plots planted in 1990, each
cultivar was observed for percentage of root
damage. Table 1 shows the results of these
'Regal' showed higher resistance to
weevil damage than any other variety in
the trial. This resistance had been
observed earlier by Dr. Duke and others.
'Regal', with its bright purplish skin,
showed no visible signs of weevil
infestation. It and the other cultivars had
been cultivated deeply to keep roots below
the soil surface. The resistance was
observed even though weevils trapped were
4% higher in numbers than for the other
varieties. 'Regal' was rated as a good
yielder, but poor keeper.
'Beauregard' roots developed much
faster than the other varieties. The roots
began swelling near the soil surface, thus
providing exposure to weevils.
'Beauregard' was an excellent
yielder/keeper, but did have some weevil
damage (30% of crop damaged).
'Excel' suffered a moderate
amount of weevil damage (65%+). Its roots
were exposed as in the case of
'Beauregard', but took longer to develop. It
is an excellent yielder with fair storage life.
'Excel' also showed good signs of nutsedge
suppression both in 1990 and 1991.
Other varieties tested results are
outlined in the table.
Dr. Richard Sprenkel, IFAS IPM
specialist, Quincy, assisted in the weevil
trapping procedure. They found weevils to
be unusually high where sweetpotatoes
followed sweetpotatoes. Even so, as has
been stated, 'Regal' showed good resistance
even though it was planted in 1991
following sweetpotatoes in 1990 on the
This summarizes the study. George
Henry has more detailed information if
(J. M. Stephens/George Henry,
S.Potato Storage Drought Possible
Weevil Flea Beetle Wireworm Grubworm Cracks in Decay or or Shelf Resist- Future
Damage Damage Damage Damage S.Potatoes Soil rot Life ance Yields
Beauregard XX XX 0 0 0 X E E E
Excel XXX X X 0 0 XX F E E
Jewel XX XXX X XXX XX X F G G
Regal 0 0 X 0 0 0 P E G
Southern XX 0 0 0 X X F E G
Sumor XX XXX X 0 0 X G G E
XXX Greatest Amount of Damage
XX Damaged Somewhat 35% or
X Lesser Amount of Damage -
0 No Damage 0%
65% or over
20% or less
Prepared by Extension Vegetable Crops Specialists
Dr. D. J. Cantliffe
Dr. S. M. Olson
Mr. J. M. Stephens
Professor & Editor
Dr. G. J. Hochmuth Dr. D. N. Maynard
Assoc. Professor Professor
Dr. S. A. Sargent
Dr. C. S. Vavrina
Dr. W. M. Stall
Dr. J. M. White