COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
STATE OF FLORIDA
COLLEGE OF AGRICULTURE, AGRICULTURAL EXTENSION SERVICE
UNIVERSITY OF FLORIDA, AND VrSclitab Crop Specialists COUNTY AGENT AND
UNITED STATES DEPARTMENT OF HOME DEMONSTRATION WORK
AGRICULTURE. COOPERATING V E G E T A R IA N GAINESVILLE, FLORIDA
July, 1~ 6
TO: COUNTY AGENTS, ASSOCIATES AND ASSISTANTS
IN THIS ISSUE:
1. Announcing Tomato Growers' Institute
2. Lowering Soil Surface Temperatures
3. Trueness to Original Type in Charleston Gray
4. Cabbage Bacterial Spot Control
5. Dimethoate (Cygon) on Potatoes
6. Onion Spacing and Culture
7. Nematode Control in Sweet Corn
3. New Pesticide Approvals for Vegetables
1. ANNOUNCING TOMATO GRO11ERS' INSTITUTE
The date, time and place for the "Third Annual Tomato Growers' Institute'
have been selected. The program will cover timely topics such as varieties,
fertilization, nematodes, diseases, insects, labor and market competition.
This is an opportunity to get some of the latest information on tomato production.
County Agents in central and south Florida should urge their growers
to attend. Put this information on your calendar right now!
WWI-JT: South Florida Tomato Growers' Institute
tEET: 9:15 A.M., Thursday, September 10, 1964
T IERiE: Fort Pierce, Florida (Meeting to be held at
Port St. Lucie Country Club just a few miles
south of Fort Pierce)
2. LOWERING SOIL SURFACE TEMPERATURES
Each summer vegetable growers struggle to obtain good germination
and seedling growth on a number of vegetable crops. Large seeded crops
such as beans and sweet corn which are seeded rather deeply, may die-off in
the seedling stage even though germination is satisfactory. "Damping-off: is
the usual diagnosis but, it may not necessarily be so.
Temperature of a loose, dry surface soil may register between 1200 to
1350 F. between midday and 3 p.m. on a summer day in July or August. Such
temperatures are capable of actually killing germinating seedlings of many
crops even though the root-system may be in an area of adequate soil moisture.
One of the simplest devices for lowering soil-surface temperature is shade.
This may not be feasible except in transplant beds. However, irrigation is
available for a large portion of Florida's vegetable acreage. By maintaining
the soil surface moist at all times, temperatures in that zone can be reduced
sufficiently in many cases to permit satisfactory germination and early growth.
3. TRUENESS TO ORIGINAL TYPE IN CHARLESTON GRAY
For the past three or four watermelon seasons, we have noted an increasing
number of criticisms of the Charleston Gray variety of watermelons. Growers,
Extension workers and buyers have voiced the complaint that Charleston Gray
has changed over the years to a shorter, blockier fruit type making it less
desirable than the original (as they remembered it) Charleston Gray.
To determine if these allegations were true or not, Dr. V. F. Nettles at
Gainesville resurrected some long-stored seed with the original code number of
51-27 from Dr. J. M. Crall at Leesburg. It was planted for comparison with
present-day seed of Charleston Gray from several large, reputable seed companies.
The results of these tests were quite revealing. Charleston Gray had not
changed as many of us might have thought. Watermelon produced from the old
and most of the new seed did not differ significantly in size, shape, skin
color and internal qualities. In other words, Charleston Gray is still as good
today as it was when introduced more than ten years ago. Note There were
some differences between sources of the new seeds. In his test plots over the
years, Dr. Crall has made observations which concur with Dr. Nettles' results.
4. CABBAGE BACTERIAL SPOT CONTROL
Following the discovery that a bacterium was responsible for the specking
disease in cabbage and other leafy crops, Dr. Wehlburg at Belle Glade initiated
tests to try to find a practical control. The most promising treatment was
a combination of basic copper -. Maneb -; Plyac (4 Ibs. -:- 1 Ibs. -- 4 oz.)
applied twice a week during the growing.
Previously, we had suggested use of basic copper for this disease. Based
on Dr. Wehlburg's preliminary results, we now suggest a basic copper and maneb
combination. This combination will not give complete control but will reduce
severity of the disease.
5. DIMfETHOATE ( CYGOH ) ON POTATOES
Recent work on dimethoate confirms previous results on the effectiveness
of this material for control of aphids and leafminers on potatoes. In a test
conducted by Dr. Wolfenbarger at Homestead, dimethoate outperformed all other
approved material in the control of these pests of potatoes.
Circular 193D gives the proper rates, time, interval, etc., on the use
of dimethoate on potatoes as well as watermelons and tomatoes. See discussion
under "New Pesticide Approval" for use of dimethoate on peppers.
6. ONION SPACING AND CULTURE
A recent study concluded by Mr. Hayslip and associates at Fort Pierce
should convince skeptics that Florida can grow onions. The test included a
unique method of fertilizer placement in that the majority of the fertilizer
was placed in a band about one inch deep in the center of the two-row bed of
onions and covered with a 12-inch strip of plastic.
The largest yield of graded onions (Texas Grano 502 Variety) was obtained
with a one-inch spacing in staggered rows (two rows 1 3/4" apart with onions
in each row 2" apart). As the spacing increased, yields were decreased but
the onions were larger and less slab-sides than in close spacing. Highest
yield of graded onions was 37,900 pounds or approximately 738 bushels.
The limiting factor in some seasons is curing. Dr. Gull at Gainesville
has shown in preliminary work that onions can be cured artificially in 40 hours
at temperatures not exceeding 1100 F. provided there is good circulation of air.
Field curing when possible is still the most economical method of curing onions.
7. NEMATODE CONTROL IN StEET CORN
Sweet corn grown on sandy soils infected with stubby-root nematodes responded
to fumigation in tests conducted at Sanford by Dr. Rhoades. Sweet corn yields
were increased significantly by fumigation with D-D and EDB on a broadcast basis.
D-D was superior in degree of control.
The test served also to demonstrate how fast stubby-root nematodes "bounce
back" after treatment. At harvest time, the largest population of stubby-root
nematodes was found in D-D and EDB plots which produced the high yields of corn.
G. NEW PESTICIDE APPROVALS FOR VEGETABLES
a Phosphamidon on Eggplants
This material was recently approved for use on eggplants at rates
of k pound per acre with an interval of three days between last
application and harvest.
b Dimethoate on Peppers
Approved for use on pepper at 1/3 pound active per acre with a
time interval of 14 days between last application and harvest.
c Zinc Ion Maneb Complex (Dithane M-45) on Tomatoes and Peppers
This fungicide was mentioned in the last Vegetarian as having
approval for use on potatoes only. It is now approved for use on
tomatoes (at 1.5 Ibs. actual per acre) and peppers (at 1.8 Ibs.
actual per acre) with a limitation that it cannot be applied after
fruits begin to form. A combination of Dithane M-45 (1.5 Ibs.) --
tribasic copper sulfate (4.0 lbs.) was the best of seven treatments
tested by Dr. Stall at Fort Pierce last season on tomatoes for
bacterial spot control .After fruit begins to form use regular IManeb
and basic copper sulfate for bacterial spot control.
VOTE! The use of trade names in this publication is solely for the purpose
of providing specific information. It is not a guarantee or warranty of
the products named and does not signify that they are approved to the ex-
clusion of others of suitable composition.
James Montelaro F. S. Jamison, Head
Associate Vegetable Crops Vegetable Crops Department
Specialist Tfl-t r LAxs
Mason E. Marvel
Associate Vegetable Crops