COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
STATE OF FLORIDA
COLLEGE OF AGRICULTURE. AGRICULTURAL EXTENSION SERVICE
UNIVERSITY OF FLORIDA, AND COUNTY AGENT AND
UNITED STATES DEPARTMENT Vegetable Crop Specialists HOME DEMONSTRATION WORK
OF AGRtCULTURE, COOPERATING GAINESVILLE, FLORIDA
VE G ETAR IAN
No. 12 September 5, 1951
SMr. County Agent:
0, We realize there are some very outstanding
? questions in your mind as the Fall vegetable
Season bears down on you* Will our stand as of
R this date mean that we're giving the final answer?
No, not by a long shot.
We want you to have in mind that what we say
~ here represents current viewpoints you should have
/ based on the results available, As the results
accumulate the picture may shift in any direction
SOIL FUMIGATION? how's that for a starter?
The evidence to date indicates that soil fumigation on a field scale in
vegetable production is still to be viewed with a critical eye.
Certainly there have been some outstanding responses to fumigation, depending
on the source of the report. But YOU, as a county agricultural agent, consider some
of the facts not so highly publicized--but of definite importance to your work and
the grower you advise
Take for example this instance in the Gulf Coast Station's annual report manu-
script for the year ending June 30, 1951. Seems the cantaloupe variety trials
(Project 391) were abandoned
"Land which was to be planted was known to be heavily infested with root knot
and was treated with complete fumigation at 1 foot spacing 6" deep 20 days before
plant setting. Plants were grown in sterilized soil in bands and transplanted after
two true leaves had formed. Plant growth was delayed somewhat by low temperatures,
but it was soon obvious that something other than this was wrong. Inspection in-
dicated that although the area had been fumigated for root knot, the field had some-
how become reinfested and that the young seedlings were so badly infected that the
plant stand was reduced to less than 10% in some plots."
Enough to re-emphasize that fumigation is not always a sure-cure? If you want
to get technical and really go into the problem we suggest the comments on microbio-
logical studies following fumigation of seedbeds in the Florida Agricultural Experi-
ment Station, June 30, 1950, Annual Report.
If you'll check the 1950 results, here's how it now appears in the manuscript
of the Gulf Coast Station report for the year ending June 30, 1951, These were
spring tests to determine the residual action of nematocides applied in-the-row on a
field scale using DD, EDB, calcium cyanamid, and technical chlorobromopropene CBF-55
three weeks prior to the date of planting.
"The stand of squash was significantly decreased by DD and CBP-55. Cyanamid and
CBP-55 adversely affected the number of tomato plants surviving transplanting. There
were no significant differences in fruit yield between the check and any of the fo:-.*
fumigation treatments in the spring crop. Root knot was not a problem until late in
"From a microbiological point of view the fumigants exerted little or no effect
on the number or species of soil fungi. However, nitrification or the conversion -f
ammoniacal nitrogen to nitrate nitrogen was significantly depressed by all four fu-:- -
gants. This depressive action was noticeable for fro* seven to 10 weeks after fumi-
gation. DD and cyanamid produced the greatest depressing effect on the nitrifying
power of the soil."
Just our way of saying it's fine when it works, BUT---
NABAM VS. ZINEB AND CUTICLE DAMAGE OF TOMATOES?---see letter of April 27the
You'll remember our earlier references to this type of spray injury on tomatoes.
State Project 291, Sub-Tropical Station, Homestead, in the manuscript for the
Annual Report for 1951 reads something like this:
"Testing to determine the factors responsible for and to alleviate the injury
to tomato fruit and foliage that has resulted from using nabam sprays, fruit injury
occurred with all combinations of nabam plus zinc sulfate. Filtering the nabam or
adding quantities of the sediment commonly found in drums had no effect on fruit in-
jury. The injury was eliminated by using B1956 (spreader-sticker), and reduced by
lowering the spray pressure from h00 to 200 lbs. Nabam and zineb used alone, or zinc
sulfate used with zineb, did not cause fruit injury. These results suggested that
the factor responsible for fruit injury was a reaction product of nabam and zinc
At the Gulf Coast Station, Bradenton, State Project 449 annual report manu-
script for 1951 shows studies of five schedules:
1. Copper and nabam alternated weekly, with wettable DDT each time copper was
2. One application of copper to tvo of nabam, with wettable DDT in the mixture
every other week.
3. Same as No. 2 except zineb substituted for nabam,
4. Copper alternated with nabam for first-6 weeks, then phygon XL replaced
copper for the remainder of the season, with DDT wettable combined with the
5. Zineb weekly, wettable DDT every two weeks.
Although Manasota is known to be very susceptible there was only slight develop-
ment of the damage, Damage on fourth and fifth harvest fruit indicated thefollowing:
"Schedules 3 and 5, which received no nabam, showed no cases of the damage.
There were no significant differences between schedules 1, 2 and 4. However data
show the amount of cuticle damage varied with dose and pressure. Most important,
data show that use of spreader-sticker at 4 ounces per 100 gallons sharply reduced
the injury, though failing to prevent it in any plot."
In another experiment reported in Gulf Coast Project 449 the injury was re-
ported to be very severe. This test was given four applications of ferbam in ad-
dition to the routine applications of nabam and copper.
"Analyzed data indicate that the cuticle damage was less severe on ground
tomatoes than on those staked and pruned to a single stemA" Also shown were some
FUNGICIDES CONTROL LEAF BLIGHT OF SWEET CORN?---see letter of April 27the
This cooperative project was described in an earlier letter and here again
we'll give our interpretation of how it reads in the manuscript for the 1951 Annual
Report. From State Project 587, Sub-Tropical Station, Homestead:
"Sprays applied as a complete cover on a regular schedule before the disease
was established were superior to applying fungicides only with budworm insecticidal
sprays, or attempting to check the disease after it was established. Among the fun-
gicides tested, all in combination with DDT, zineb gave the best results followed in
order by nabam plus zinc sulfate, ferbam, ziram, a puratized agricultural spray, and
phygon XL. Severe injury was observed in plots sprayed with the last two materials
Mixtures of DDT emulsion with all fungicides formulated as wettable powders caused
formation of greasy clumps."
Over at the Gulf Coast Station again you can check the observations we passed
on to you last April. In addition to the three first crop observations you can add:
"(4). In preventing the development of the disease on young corn plants zineb at 120
gallons per acre on a 3-day schedule showed clear superiority to zineb at 60 gallons
per acre on a 6-day schedule, the latter schedule being that for application of DDT
emulsion for budworm control."
In a second crop at Bradenton "thorough spraying with zineb and nabam gave
economic control with an increase in yield much greater than needed to cover the cost
of applying fungicides; the best treatment was 15 applications of zineb with which
DDT wettable was combined on 11 occasions."
FOLIAR FEED MAJOR ELEMENTS?--see letter of April 27th.
Just to refresh your memory we'll make some quotes you may not have picked up in
your other information on this subject. These come from miscellaneous projects re-
ported in the manuscripts of the Florida Agricultural Experiment Station annual re-
ports for the year ending June 30, 1951.
Horticulture, Main Station, Gainesville:
"In the fall of 1950, three levels of nitrogen were applied to the soil com-
pared with three levels of'urea nitrogen applied to the foliage of tomatoes. The
results of this experiment, which have limited application, would seem to indicate
that no benefit was derived from foliar applications of urea nitrogen, whether alone
or in combination with soil nitrogen, when compared with equal amounts of nitrogen
applied to the soil
"In the spring of 1951, urea foliar sprays were compared with side dressings
of nitrate of soda as sources of supplemental nitrogen. No significant differences
were found between the two sources in total yield or number of fruit harvested."
Gulf Coast Station, Bradenton:
"Trials indicated that crops with high fertility requirements, such as the
tomato, showed little or no response to foliar feeding as far as the major elements
were concerned. Tomato plants bedded and side dressed with a total of 1800 pounds
of fertilizer per acre and receiving a weekly spray application of nitrate of potash
or of a soluble 13-23-13 fertilizer over a 7 week period gave no increase in yield
over those not receiving such sprays Plots top dressed with nitrate of potash sig-
nificantly outyielded plots sprayed with nitrate of potash or soluble urea over a 4
week period at the time of harvest. Similar results were obtained in both fall and
Sub-Tropical Station, Homestead:
Compared sprays of borax, ferbam, and three soluble fertilizers "All
treated plots yielded more than the check but the differences were not significant."
Strawberry Investigations Laboratory, Plant City:
"Nine weekly applications of commercial nutrient spray materials containing
all primary and trace elements were made to strawberry plants during October to De-
cember, in addition to the regular fertilizer program of 300 pounds of commercial
fertilizer per acre per month. There were no significant differences in plant
growth and yield between sprayed and unsprayed".
AT PRESENT RATE OF FINDING SAME, WON'T WE RUN OUT OF TROUBLES ONE OF THESE DAYS?
Keep in mind split personalities, split infinitives, split plots---now tomatoes
get in the act. (State Project 402, Gulf Coast Station, 1951)
"This disorder is characterized by a pronounced dwarfing of the plant. In
severe cases the stem splits near the growing tip, often leaving a hole through the
stem if and when growth is resumed. In moderate cases a longitudinal cut through the
stem reveals internal necrosis near the base of the growing point and frequently in
areas below. On entire fields or isolated plants, on old and new soil, and no cor-
relation apparent with fertilizer or with any minor element,"
Dr. LI O. Gratz, Assistant Director, Research, cooperated
in making available the manuscripts quoted herein,
Make an effort'to attend the Florida State Horticultural Society meetings this
year October 30, 31, November 1 and 2, West Palm Beacho O.K. So you have zillions of
meetings to attend. Wanted YOU to know that the vegetable section will offer a well-
rounded program designed along grower lines of interest, and featuring one of the
panel discussions you are familiar with through your area vegetable meetings
Hort. FEM:RV 4
9/5/51 -- 250 F.1. Jamison, Vegetable Crop Specialist