FLORIDA AGRICULTURAL EXTENSION SERVICE
UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
Vegetable Crops Department
December 23, 1968
fO: COUNTY AGRICULTURAL AGENTS
IN THIS ISSUE:
Cover Crops and Fumigation Interactions
Wash Water for Tomatoes
Statistics on Florida Vegetables
Effects of Copper on Cabbage Black Speck
1. Cover Crops and Fumigation Interactions.
Dr. Harlan Rhoats of the Central Florida Experiment Station at Sanford
recently completed a three-year study of soil fumigant-crop effects on
subsequent nematode populations and vegetable crop yields. The study was
summarized in the July, 1968 issue of the Plant Disease Reporter. The results
*re presented in the following table:
Effect of cover crop and soil fumigation on return of
the stubby-root nematode and yield of cabbage and sweet corn.
1965 1966 1967
1965 1966 1967
Sweet corn yield
1965 1966 1967
nema ades built
in c.-;p yield.
stubby-root nematodes per pint of soil.
bin 1966 and 1967 sting
up in check plots following sesbania, causing a further reduction
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA. COLLEGE OF AGRICULTURE.
UNIVERSITY OF FLORIDA. U. S. DEPARTMENT OF AGRICULTURE. AND BOARDS OF COUNTY COMMISSIONERS, COOPERATING
The above table warrants close study. Dr.Rhoades in his report
explainedd the salient points:
"In all cases the stubby-root nematode returned to far higher
populations on the cabbage following soil fumigation in plots treated
with DD and EDB than with DBCP. Check plots were intermediate in
this respect. Re-establishment of this nematode occurred at a slower
rate following the cover crop of crotalaria than for sesbania. A
combination of crotalaria and fumigation with DBCP gave excellent
control of this nematode during the experimental period.
"There were no significant increases in cabbage yield for soil
fumigation following crotalaria, but following sesbania which built
up populations of sting (Belonolaimus longicaudatus) and other plant
nematodes, there was a significant increase for all fumigant treatments
in both 1966 and 1967. Sweet corn growth was more vigorous and yields
were the highest in every year where DBCP had been applied for the
previous cabbage crop (Table 1). This was especially true in 1966 when
the highest populations of the stubby-root nematode were re-established
ci the cabbage.
"From the results obtained in these experiments, DBCP is apparently
far more residual in its action than DD or EDB and, where growth of
crops susceptible to stubby-root nematodes is contemplated, this could
be an important factor to be considered."
Crotalaria spectabilis has been recognized as an excellent cover
crop on nematode-infested soil for many years. However, it has almost
disappeared from the scene because of the fact that crotalaria seeds are
r-xic to animals. It is almost impossible for growers to find seed for
wantingg it as a cover crop now.
DBCP (Nemagon and Fumazone) is not labeled for use on all vegetable
crops. Check the label before using it on any crop.
2, Wash Water for Tomatoes.
Growers washing tomatoes in the field to remove sand and packinghouse
operators recirculating wash water for tomatoes are apt to increase
problems from bacterial soft rot. This was demonstrated in a study by
Dr. R. H. Segall of the United States Department of Agriculture in
O.-lando. He observed that washing mature-green tomatoes in the field
increased the incidence of bacterial soft rot. However, washing did not
increase the incidence of alternaria on fruit.
Dr. Segall attributes increased decay of field-washed fruits to the
h;gh bacterial population introduced into the field washer throughout the
day, primarily from tomatoes Infected with the organism. The chlorine-
containing compounds have been used successfully to reduce bacterial
populations in wash water. Three in common use are chlorine, sodium
hypochlorite, and calcium hypochlorite. Use these according to label
instructions and be sure to add more to the wash water from time to time
t- maintain the required concentration of chlorine.
Packinghouse supervisors can use this information to their benefit
i," recirculated wash water is used in the packinghouse operations. Here,
too, wash water can be a main source for contamination with bacterial
3. Statistics on Florida Vegetables.
Florida probably has some of the best statistics and other related
information in the nation on commercial vegetables. They include reports
giving information on acreage, production, value and areas, etc., crop
plantings, acreage-marketing guides, shipments, prices and demand,
development of crops in progress, costs and returns, and many others.
County agents, production managers, supply people and others working
within the vegetable industry could benefit immensely from the information
available in these reports.
The reports are not for wholesale distribution to all citizens. They
are intended for those who produce vegetables or in some way service the
The names of the reports and where they may be obtained are as
I. Florida Crop and Livestock Reporting Service
122 Woodard Street, Orlando, Florida 32803
A. Florida Agricultural Statistics, Vegetable Summary (annually)
B. Florida Weather and Crop News (weekly)
C. Florida Vegetables
1. Potato Acreage and Production (monthly)
2. Celery Acreage and Production (in season)
3. Pole Beans, Dade County Acreage Planted, etc.
(weekly, in season)
4. Acreage and Indicated Production (periodic)
II. Market News Section, Florida Department of Agriculture
Post Office Box 20273, Orlando, Florida 32814
A. Florida Produce Guidelines (weekly, in season)
III. Department of Agricultural Economics, IFAS,
University of Florida, Gainesville, Florida 32601
(Also available from county agents.)
A. Costs and Returns from Vegetable Crops in Florida (annually)
IV. Department of Vegetable Crops, IFAS,
University of Florida, Gainesville, Florida 32601
A. Acreage-Marketing Guide--Florida Vegetables (annually)
These are some of the more important reports available. There are a
number of periodic bulletins and reports issued from time to time by
government agencies serving Florida. Among these is the Minimum Temperature
Summary Report prepared by the Federal-State Frost Warning Service in
Lakeland. It is an excellent reference for the vegetable industry.
!. Effects of Copper on Cabbage Black Speck.
Black speck, sometimes referred to as "pepper spot' is a disease of
winter cabbage in Florida which causes serious loss in transit and storage.
The disease, as the name implies, appears as numerous, black specks on the
inner leaves of the cabbage head. Black speck seems to intensify on the
cabbage heads when held under refrigeration. Exact causes for this disorder
have not been determined, but research at Sanford and Belle Glade, Florida,
and in other states has pointed out some factors associated with it.
Until now, no pathogenic organisms have been found associated with the
problem. Some cabbage varieties and hybrids are more susceptible to the
disease than others. The disease is often accentuated by certain soil
factors, weather, and foliar sprays.
Researchers Strandberg, Forbes and Darby at Sanford and Berger at Belle
Glade have investigated this cabbage disease rather intensively in Florida.
in addition to noting varietal differences in susceptibility, they observed
that the application of copper by foliar sprays caused a significant intensi-
fication of the disease.
Until further information is developed on black speck of cabbage, growers
are advised to go easy on the use of copper in fertilizers or in any spray
materials. Soils. with high copper contents should be avoided when possible,
or limed heavily (to pH 7.0) to reduce soluble copper content. Growers
might also check with their seedmen to obtain resistant varieties and hybrids
for small trial plantings. Field performance of the more resistant lines
has not been adequately determined as yet.
/ James Montelaro Mason E. Marvel
Vegetable Crops Specialist Associate Vegetable Crops Specialist
Victor F. Nettl6s' James M. Stephens
Acting Chairman Assistant Vegetable Crops Specialist