STATE OF FLORIDA
COLLEGE OF AGRICULTURE, AGRICULTUfAL EXTENSION SERVICE
UNIVERSITY OF FLORIDA, ANO Vegetable Crop Specialists COUNTy GET AN,
UNITED STATES DEPARTMENT O HM DEM TON O
AGRICULTURE, COOPERATING GAIN ESVILLC 11. niOA
NO. 53 December, 1960
TO: County Agents
Many of you attended Field Days last spring to observe vegetable research in
progress. At that time most of the research was not completed and results could not
be given. We plan to briefly summarize the results of research in vegetables for
the 1959-60 season and forward it to you through our "Vegetarian" newsletter.
This letter covers research work conducted on vegetables at the Potato Investi-
gations Laboratory at Hastings and the Watermelon and Grape Investigations Laboratory
at Leesburg, Florida. Our thanks go to Dr. Eddins and Dr. Crall for their splendid
LEESBURG STATIC (1959-60 SEASON)
I Investigations of and Control of Pusarium Wilt of Watermelon
Four selections (F59-1, F59-2, F59-3 and F59-4) of a wilt-resistant Garrison-
type watermelon were tested in replicated trials with Charleston Gray, Summit,
Garrisonian and USDA Line 59-7. Selections F59-3 and F59-4 were comparable with
Summit which is highly resistant to wilt. Selections F59-1 and F59-2 were inter-
mediate between Charleston Gray which is moderately resistant to wilt and Garrisonian.
a highly susceptible variety. Yields of all selections were equal to and matv-or
later than Charleston Gray. Fruit quality in each selection was excellent.
II Investigations of and Control of Fungus Diseases
A. Control of Gurny Stem Blight
1. Spraying or drenching watermelon seed with several rates of fungicides
(phaltan, maneb. omadine and zineb) at various stages during the seed
clear-'ig process failed to completely disinfect the seed of the gE.-r,-
2. Early fungicidal sprays In three greenhouse tests fungicidal sprays on
newly emerged seedlings from commercial seed prevented natural infection
of the cotyledons by gunmy stem.
B. Fusarium Wilt
Wilt in 1960 was slight. Results of 1959 tests showed fusarium wilt
developir.- in each variety as follows:
Florida Giant (77;,), GCrrisonion (59%), Blackstone (17%), Congo (15')
and others less than 10) each.
III Pollination of Watermelons by Honeyboes
Fruit set and yields after 8 or more bee visits p.?r flower were -sirf.:'f"i .-'"-an
better than after 4 or less visits. No melons were set where no bee visits iwere
permitted. Fruit set and yield after hand pollination were compara.&lc to those
after open pollination.
Percentage of fruit set was directly correlated with ovary length (measured on
the morning of flower opening). No fruit set on ovaries under 17 mnn. long, 5, on
ovaries under 20 mm., 38% on ovaries 20 mm or over, and 93% on ovaries 28 niM or over
(using C-j-rleston Gray variety).
Bee activity ordinarily began around 6:30 A.M., was most intensive from 7 to
10:00 A.M., and diminished thereafter until blossoms closed around noon. The average
duration of each bee visit was about 6 seconds. The lowest rate of bee visitation
observed was 7.3 visits per flower per hour.
IV Fungicidal Control of Watermelon Foliage Diseases
In a comparison of 7 fungicidal spray treatments, maneb, phaltan, captain 10:
and zineb plus maneb were superior in their control of gunmy stem blight. There
was a yellowing and burning on the leaves and exposed fruits after the seventh
application of phaltan, as in 1959, and a yellowing and hardening of the edges of
the older leaves following the last application of maneb. There were no significant
differences in early and total yields among the treatments primarily because water-
melon diseases were of relatively minor importance in 1960.
V Testing and Evaluating Insecticide for Watermelons
An experiment designed to evaluate chemical control of leafminer on watermelon
included the following spray treatments (listed in order of their effectiveness):
dibrom E (not approved) 16 ounces (actual toxicant per 100 gallons); parathicn W,
4.8 ounces; diazinon W, 4 ounces; parathion W, 2.4 ounces; diazinon W plus maneb W.
4 ounces plus 19.2 ounces; demeton E, 6 ounces; trithion W, 4 ounces; phospha,-dor E
(not approved) 6 ounces; untreated check. Dibrom, parathion at both rates, diaziron
and diazinon plus maneb were all significantly better than the check (5 percent level).
None of the materials were effective 6 days after application.
Thimet (not approved) 8 percent granular at 1.8, 3.6 and 5.4 grams per hill
and di syston (not approved) 5 percent granular at 2.4, 4.8 and 7.2 grams per '_ill,
applied post-emergence on the soil, were not effective in leafmriner control.
VZ Variety Trials
Charleston Gray and Indiana 133, a line selected from Charleston Gray for
increased wilt resistance, were the outstanding long-melon-type varieties in this
trial. USDA lines 59-6 and 59-7 and Tri-X 313 were the most prero iing round-moelon-
type varieties tested. Although not highly resistant to Fusarium wilt, both 59-7
and Tri-X 313 appear promising enough to warrant grower trials.
In a replicated test with 8 entries, USDA 59-7 was very early in maturity,
Charleston Gray and Summit early and all other entries somewhat later maturing.
Yields of Summit, Charleston Gray and the 4 Florida lines were comparable, but USDA
59-7 and Garrisonian produced significantly lower yields.
Most promising lines ( of 8 entries) were Delta Gold, Seminole, and Rio Gold.
All of these compared favorably wit' HaC.les Best Jumbo and P1,R-45 in quality. All
entries were superior to Jumbo and P,-45 in resistance to leafspots.
VII Miscellaneous Research
A. Spreader-sticker test:
There were only slight differences among additives in the total amount of
fvngicide deposited on the foliage immediately after application. After 1.25 inches
of rainfall, C0 or more of the fungicide on the upper surface and 20% on the lower
surface were lost. Loss of fungicide after slight amounts of rain (0.10 inches),
particularly from the upper surfaces of leaves, was greatest after treatments with
'ood wetting characteri tis.
B. Soil Fumigation:
Eleven chemical treatments were compared for their control of soil fungi
and rootknot nematodes associated with the culture of watermelons on old land. All
materials were applied both as broadcast (entire area) and band treatments.
The movement of soil from one plot to another by high winds and washing
rains and spotty infestations of both the Fusarium wilt organism and rootknot nematode
resulted in extreme sampling variations so that differences in stands or yields
between treatments were not significant and no treatments were effective in reducing
rootknot galling or losses from Fusarium wilt.
C. Factors Affecting Gourdnecking in Watermelon:
Plants of the variety Fairfax were grown under the four possible combinations
of conditions of high and low levels of soil fertility and soil moisture. Fruits
were harvested as soon as their final shape with regard to gourdnecking could be
determined. Approximately 11 percent of all fruits developed gourdnecks, but the
amount of gourdnecking was not affected by soil fertility and soil moisture levels,
D. Cultural Practices Affecting Watermelon Maturity:
In a field trial to determine the effects of various cultural practices on
hastening maturity of watermelon, more vigorous early season growth and increased
yields of early melons resulted both from the use of a clear polyethylene plastic
cover over the bedded area and from loping the beds (300 slope to south). Total
yields also were larger from covered beds. Early season soil temperatures were
higher under plastic covers and in sloped beds, but factors such as better moisture
and fertilizer retention under the plastic covers were believed to be also p.rtily
responsible for the better early season growth of watermelon plants. The effects
of planting date and transplanting on earliness were not decisive this season.
HASTINGS STATION (1959-60 SEASON)
I Investigation of Factors Affecting Potato Production on Old Land
A. Cover Crops:
In an investigation of seven different summer cover crops, highest yields of
p+t-toes were obtained following corn or crabgrass, which has also been true in
pr.i-ious years. The percent organic matter in soil following corn was 1.53 and in
fellow plots 1.26.
Yields of potatoes following one winter crop of rye or oats were increased
20 percent compared to continuous potatoes.
On old ind, higher potato zPi'ds were obtained by using the conventional
200 pounds of P205 per acre rather t;.n higher or lower rates. Cn new land, which
contained 16 pounds of exchangeable P205 per acre before fertilization, potato yields
increased as the amount of applied P205 increased. Specific gravity of tubers was
inversely related to amounts of applied P205, ranging from 1,0755 to 1.702 for 50
ard 400 pounds P205 treatments, respectively.
When potatoes were fertilized with 0, 25, 50, 100 and 200 pounds per acre of
M0O on both new and old land, the only significant yield difference occurred between
the 25 and 200 pound rates on old land, the latter rate producing lower yields.
E. Source of Potash:
Higher yields of potatoes were obtained by using fertilizer containing all
muriate rather than all sulfate as the source of potash; by using 200 pounds per
acre of potash rather than 100 or 300 pounds; and, by using broadcast method of
application rather than band application.
F. Sidedressing Katerials;
Fo'tilizer containing both amnonical and nitrate sources of nitrogen in-
creased potato yieli more than those containing only nitrate. Foliar sprays of
10-'0-10 reduced potato yields.
Second year differences in potato yields due to sawdust treatments were
similar to first year's results. Yields of 122, 138, and 159 hundred-pounds of size
A potato tuib.r. per acre were obtained from 0, 10 and 40 tons of sawdust per acre,
r--c:ctively. C'i--hurdred pounds per acre of supplemental nitrogen from ammonium
nitrate before planting increased yields to 127, 151 and 166 hundred-pounds per acre
in the 0, 10 and 40 ton of sawdust treatments, respectively. Soil volume weight
measurements of 1.2, 1.1 and 1.0 were obtained in the 0, 10 and 40 ton rates.
II Variety Trials
None of 26 varieties and 23 USDA seedling selections excelled Sebago, the
standard variety, in chipping and market qualities of tubers. Two white varieties,
Pungo and Plymouth and three red varieties, Red LaSoda, Redsldn (all suggested for
trial planting) and Red Pontiac recommendedd) produced greater yields than Sebago
although differences were not statistically significant.
aEerald, a new early variety, again produced a high yield and appeared
suitable for commercial trials. Glory of Enkhuizen, Greenback, Early Glory and
Marion 1:arket were the outstanding midseason varieties in yield and market qualities.
Snowball Imperial and Snowdrift excelled other varieties in yield and
quality of flower.
III Fertilizer Requirements of Cabbage
7s.ults of lining studies suggested that pH of 5.7 to 6.0 is preferred for
cbba In a dry season 24 lbs. of nitrate N as sidedressing produced maximum
yields following a basic application of 1600 pounds of 7-9-9 fertilizer. In three
wet seasons two to three sidedressings with 24 lbs. of nitrate N per application
per acre produced maximum. yields -;ith the same amount of fertilizer at transplanting,
Sidedressings were made 23, 66 and 96 days after transplanting.
IV rTeting and Evaluating Insecticides
Of thirteen insecticides applied every two weeks to cabbage the following
gave best control at the indicated actual toxicant per acre:
1. Cabbage looper Parathion 4 oz.; endrin 3.2 oz.; g-uthion 8 oz.;
mnthyl trithion 8 oz. (not approved); diazonin 4 oz.; dibrom at 16 oz.;
and systox 6 oz.
2. Cabbage aphid Phosdrin 4 oz.; phosphamidon 8 oz.(not approved);and
dibrom 16 oz.
3. Green peach aphid Thiodan 8 oz.; phosdrin 4 oz.; and endrin 3.2 oz.
1. Southern potato wireworm Parathion 1 lb.; diazonin 2 lbs. and thimet
1 lb. per acre prior to planting.
2. Green peach aphid Dimetheote 6 oz. (not approved); endrin 3.2 oz.;
syston 6 oz.; thimet 8 oz.; and thiodan 8 oz. actual toxicant per acre.
Spraying cabbage plants with 25 ppm gibberellic acid 47 days after transplant-
ing had no significant effect on yield.
VI Resistance to Corky Ringspot of Potatoes
On the named varieties planted in soil infected with corky rinrspot viruzx
Red Pontiac, Sebago and White Rose showed from 29 to 72% susceptibility to the
disease. Pungo and Plymouth (both suggested for trial plantings) and Delus, Merri-
mack and Saco were immune.
VII Chemical Weed Control
DNBP at 3 and 1.5 lbs. in 100 gallons of water per acre applied before
potatoes emerged reduced weeds by 50%. CDEC applied 4 and 2 lbs. gave 38~ control,
while CDAA at 4 lbs. gave 12% control.
CDEC and CDAA were applied singly and in combination to transplanted
cabbage. Weed populations were too low for good results. CDEC at 4 Ibs. per acre
did not affect yield of cabbage. Some of the other treatments resulted in reduced
VIII Miscellaneous Studies
A. Source of Potash and Method of Fertilizer Application for Cabbage:
Density of cabbage heads and yields were not affected by using muriate and
sulfate sources of potash in 6-8-8 fertilizer applied in bands and broadcast and by
varying the amount of potash in the fertilizer.
B. Effects of Seed and Fertilizer Rates on Yields of Potatoes:
SIn recently-cleared new land, potato seeding rates were varied from 1,500
to 3,500 pounds of two-ounce cut seed per acre and the fertilizer used ranged from
1,200 to 4,200 pounds per acre. The highest and most profitable yield, 250 hundred
pounds sizes A and B tubers per acre, was produced with 3,000 pounds of seed and
3,6 ~ pounds of fertilizer per acre.
C. Efficacy of Sulfur-limestone Soil Treatment for Control of Corly
Ringspot of Potatoes:
No information was obtained on the value of the sulfur-limestone treatment
for control of corky ringspot as only a trace of the disease was present. Difference
in yields of potatoes grown in the treated and nontreated soil were not significant.
--. Assoc. Vegetable Crops Spec.
F. S. Jamison Mason E. Marvel
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