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CO-OP Research and Technical Research
Reports
Not only is USDA doing inhouse research
on the methyl bromide issue, but through the Agricultural
Research Service, more than $850,000 has been provided over the past
3 years to support work by university scientists on this issue.
Following are technical research reports from the University
of Florida's Cooperative Extension Service and the University
of California at Davis.
Progress report on USDA-ARS Specific Cooperative Agreement,
"Integrated
Management of soilborne Pests of Tomato as an Alternative to Methyl
Bromide"
Principal Investigator: D.O. Chellemi, University of Florida, North
Florida Research and Education Center, Quincy, Florida
Cooperators: S.M. Olson, R. McSorley, D.J. Mitchell, W.M. Stall,
R.J. McGovern, D.W. Dickson, T.R. Sinclair, F.M. Rhoads, J.E. Funderburk,
and J.R. Rich.
Using fall production of fresh market tomato in
Florida as the model cropping system, studies conducted in 1994 indicated
that yields identical to those obtained with methyl bromide:chloropicrin
can be achieved using soil solarization.
Soil solarization
effectively controlled populations of weeds (including nutsedge), plant
parasitic nematodes and Fusarium wilt. In addition, soil
solarization is fully compatible with standard production practices and
results in savings of over $250 per acre when compared to the cost of
fumigating with methyl bromide:chloropicrin.
Field experiments
are being conducted in 1995 to further evaluate the effects of various
combinations of chemical fumigants, organic amendments, soil solarization
and gas impermeable plastic films in combination with reduced rates of
chemical fumigants on the incidence of soilborne pests, populations of
beneficial microorganisms and yield of fresh market tomato. Studies are
also being conducted to further optimize the performance of soil
solarization and alternative chemical fumigants.
Fumigation with
Telone C-17 and soil solarization, with and without reduced rates of
methyl bromide:chloropicrin or Telone C-17, are currently being evaluated
in large 2- to 5-acre plots in three commercial tomato production
plantings.
A soil solarization field day was conducted on August
28 at the North Florida Research and Education Center. The field day was
attended by commercial growers, county extension faculty and Professor
Jaacov Katan from the Hebrew University of Jerusalem. It provided an
excellent forum for positive exchange of ideas on implementing methyl
bromide alternatives.
Progress Report on USDA/ARS Cooperative
Agreement, "Development of Alternative Technology to Methyl Bromide
Fumigation for Control of Soilborne Diseases of Strawberries"
Principal Investigator: J.M. Duniway, Department of Plant Pathology,
University of California, Davis, CA 95616
Cooperators:
W.D. Gubler, Department of Plant Pathology, University of California,
Davis, CA 95616; L.H. Aung, USDA, ARS, Horticultural Crops Research
Laboratory, Fresno, CA 93727.
The experiments reported here are
part of a larger project supported by the California Strawberry
Commission and USDA-ARS to identify chemical and non-chemical
alternatives to methyl bromide for preplant fumigation of soil in
strawberry production.
Chemical alternatives to methyl bromide
were tested in two large field experiments near Watsonville, CA. Both
fields had been fumigated previously prior to planting strawberries in a
strawberry-vegetable rotation. In September of 1993 and 1994, one of the
fields was cultivated flat, divided into three replicate blocks, and
further divided for preplant treatments of soil, i.e., fumigation with
methyl bromide/chloropicrin (67/33 percent at 325 pounds per acre),
chloropicrin (300 pounds per acre, Telone II
(1,3-dichloropropene)/chloropicrin (70/30 percent at 454 pounds per acre,
or 30/70 percent at 409 pounds per acre) or not treated.
Fumigants were injected at 20 cm depth (broadcast treatment) and the soil
was immediately covered with a polyethylene tarpaulin. Non-treated soil
was not covered. The tarpaulin was removed after five days, beds were
raised, and the strawberry cultivar Selva was transplanted (2 rows/bed)
approximately 6 weeks after soil treatment. Conventional practices for
strawberry production and pest management were followed, including
sprinkler irrigation initially and drip irrigation at bed centers in the
production season.
All chemicals used reduced total populations
of fungi in soil by 65 to 85 percent relative to populations in
non-treated soil, while total populations of bacteria were variable and
were not generally reduced significantly by the chemical treatments used.
Plant parasitic nematodes and Verticillium populations were
measured
separately and were low in all soil treatments.
All of the
fumigants listed above increased growth significantly relative to that in
non-fumigated soil. The incidence of transplant failures and plants with
recognizable diseases (e.g., Phytophthora root and crown rots,
Verticillium wilt, or collapse of unknown etiology) were equally
low in
all soil treatments. Therefore, average growth and yield differences were
due largely to overall differences in plant growth and vigor.
Berries were picked for fresh market at least twice weekly by normal
grower practice starting April 1 and continuing into November. Berry
yields for the methyl bromide/chloropicrin, chloropicrin, and Telone
II/chloropicrin treatments were nearly the same, while yields in
non-treated soil were significantly (40-49 percent) less than in other
treatments.
Although more long-term research is needed, the
results from these two experiments suggest that (a) methyl
bromide/chloropicrin, chloropicrin alone, and Telone II/chloropicrin
worked equally well on ground with a history of vegetable-strawberry
rotation and previous fumigation, and (b) that growth and yield responses
to fumigation in strawberry occurred in the absence of significant
pressure from known diseases. Even larger responses to fumigation are
expected where known soilborne pathogens are present at potentially
damaging levels.
Bed fumigation treatments are being compared in
a separate experiment at a field site near Watsonville, CA, where
Verticillium populations are high. While none of the bed
fumigation
treatments gave the level of disease control or yield expected following
broadcast fumigation with methyl bromide/chloropicrin, all the chemicals
listed above, as well as Basamid (Dazomet, 400 pounds per acre) and methyl
iodide (365 pounds per acre) increased yields significantly and reduced
the incidence of plants with Verticillium wilt by approximately 50
percent
relative to a non-treated control. Verticillium populations in soil
increased during the growth of strawberries.
In a rotation
experiment at Davis, CA, strawberries planted in non-fumigated soil
following broccoli, strawberry or a fallow treatment had equivalent growth
and yields. Broadcast fumigation with methyl bromide/chloropicrin (67/33
percent at 325 pounds per acre) before planting strawberries approximately
doubled yields.
The bed fumigation and rotation experiments are
being repeated with modifications in 1995-96. In addition, broadcast
fumigation treatments will be reapplied in September 1995 to the ground
treated in September 1993 to measure longer-term and carry-over effects of
the various fumigants used. Mechanisms underlying the response of
strawberries to soil fumigation and the epidemiology of
Verticillium wilt
in strawberry are also being researched.
[October 1995 Table of Contents]
[Newsletter
Issues
Listing]
[Methyl Bromide Home
Page]
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Last Updated: October 25, 1996 |
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