The lack of alternatives to methyl bromide, a pesticide that depletes the stratospheric ozone layer, is driving companies in the United States and Canada to apply for exemptions from the 2005 phaseout date, which was mandated in 1998 under the Montreal Protocol. The effort to replace methyl bromide has lagged because pesticide manufacturers do not want the expense and risk of registering new substitute products that will not have a large and profitable market, according to U.S. Department of Agriculture (USDA) officials. But some scientists and environmentalists say that the problem lies with the agricultural industry’s unwillingness to abandon reliance on single “silver bullet” chemicals and adopt a systems approach, such as integrated pest management.

Methyl bromide is a broad-spectrum soil fumigant that kills pathogens, insects and weeds before planting crops such as tomatoes and strawberries, says Ken Vick, senior national program leader at USDA’s Agricultural Research Service. USDA research indicates that methyl bromide will have to be replaced by a wide variety of pesticides used in combination to target specific pests on specific crops. However, the methyl bromide market is relatively small compared to other pesticides such as atrazine, and manufacturers can’t justify the costs for registering new products for this market, says Vick. If pesticide alternatives are not available or cut too much into profits, farmers could go out of business, he predicts.

More than 56 U.S. growers and farm organizations submitted requests to EPA for exemptions on Sept. 9; Canadian applications were due at Environment Canada by Oct. 30, but thanks to a cold winter climate, Canada has fewer users of methyl bromide and does not expect many applications. In addition, Canada has been working with grain millers since 1991 to adopt alternatives, such as heat treatment, and this program has cut methyl bromide use in half, from 100 to 50 tons per year, says Alex Cavadias, section head of ozone protection programs for Environment Canada. Over the same period, usage in the United States has declined slightly, from about 29,000 to just under 24,000 metric tons, according to EPA data.

Countries still have to forward exemption requests that meet the critical use criteria outlined by the Montreal Protocol to the Technology and Economic Assessment Panel of the United Nation’s Ozone Secretariat for a final decision sometime in February or March 2003, says Vick. The Montreal Protocol allows the use of ozone-depleting chemicals to continue past their phaseout dates, if no alternatives are available. In the case of methyl bromide, the Protocol for the first time will also allow exemptions for uses where the ban would cause economic disruption, says Cavadias.

Despite the difficulties experienced by the United States and Canada, a handful of countries have already successfully phased out use of methyl bromide, including Indonesia, Denmark, and the Netherlands, says Kristin Schafer, program coordinator with Pesticide Action Network North America, an environmental group. Farmers in these countries have moved to a variety of options, including compost, soil solarization using clear plastic mulch, and alternative pesticides. In addition, much of the plant nursery business in the United States has also dropped methyl bromide in favor of amending soils with compost and using pesticides selectively, according to the principles of integrated pest management, says Harry Hoitink, plant pathologist at Ohio State University. New research shows that the microorganisms in healthy, organic-rich soil activate genes in plants that boost resistance to pathogens and insects, he adds.

Efforts by companies to continue using methyl bromide past 2005 come as the United Nations Environment Programme warns in a September 16 report that the ozone layer remains vulnerable during the next decade, even with full Montreal Protocol compliance. —JANET PELLEY