ST. PAUL, Minn., Feb. 17, 1998--The EPA, acting under the Clean
Air Act, will be phasing out methyl bromide in just three years,
with all U.S. production and importation ending on January 1,
2001. Considerable research indicates methyl bromide a fumigant
against weeds, insects, nematodes and microorganisms is a potent
ozone depletor. The phase out leaves the agricultural industry
in a transitional situation, looking for alternatives.
In response, plant pathologists are hard at work testing new management
practices for disease control, especially in tomatoes and strawberries.
"The phase out of methyl bromide in the U.S. has stimulated
a great deal of creative research," says Jean Beagle Ristaino,
associate professor of plant pathology at North Carolina State
University and member of the American Phytopathological Society
(APS). Her research has led to improvements in the management
of soilborne plant pathogens by encouraging the use of ecologically-based
Use of practices that are less dependent on single-chemical strategies and more biologically and culturally focused may lead to long-term success. Promising tactics include:
- The use of other fumigants (methyl iodide has some promise and has not been implicated as an ozone depletor)
- Development of plant varieties resistant to diseases methyl bromide prevented
- Changes of cultural practices that increase the organic matter level of soil
- Soil solarization (the thermal heating of moist soil by sunlight)
- Electrical heating of soil
- Incorporation of biological control organisms
What ever the alternative, "The loss of methyl bromide certainly
presents a significant challenge to American agriculture,"
says Bill Thomas, EPA. "Currently some 75% of the methyl
bromide used in the U.S. is applied to soils prior to planting,
and another 11% is used on commodities to control pests after
harvest. Without the good work agricultural scientists, like plant
pathologists, are putting into finding and implementing alternative
pest control tools, the loss of methyl bromide could have a far
greater impact on growers, shippers, retailers and consumers,
than I believe it ultimately will."
A recent article in the APS journal Plant Disease, co-authored by Ristaino and Thomas, highlights the key ozone depletion mechanisms of methyl bromide and how its loss will impact the agricultural industry. Other details can be found at the APS web site.