Researchers developing key pesticide substitute

MOBILE, Ala. -- Auburn University researchers say they've developed a substitute pesticide for methyl bromide, a widely used pest, weed and plant disease killer that's being phased out because it damages the ozone.

For many farm operations, finding a substitute is a matter of economic survival because of their years of dependence on methyl bromide. For the pesticide industry, the right substitute could boost corporate profits as debate swirls over one of the chief environmental issues in agriculture.

Despite an outcry from farmers who rely on it, particularly in California and Florida, methyl bromide production is scheduled to be phased out in the United States by Jan. 1, 2005, under the 1987 United Nations Montreal treaty to reduce ozone-depleting substances.

Methyl bromide users argue there's no substitute as potent as the highly toxic gas, which is injected into the ground before planting. It can be fatal to humans in large doses and causes a range of neurological problems at lower concentrations.

Auburn plant pathologist Rodrigo Rodriguez-Kabana believes he's found an alternative with SEP-100, a liquid formula of sodium azide that he says significantly outperforms methyl bromide in controlling weeds, diseases and harmful, root-eating nematodes.

SEP-100 is delivered by drip irrigation under plastic sheeting without spraying or release into the atmosphere, he said in a telephone interview. It's been field-tested on crops in Auburn and Brewton, in south Alabama.

In medicine, sodium azide has been used to reduce blood pressure in emergency situations.

Rodriguez-Kabana said the methyl bromide replacement could be on the market as early as the 2004 growing season for a limited number of crops. If the U.S. Patent Office grants a patent on the sodium azide formula, Auburn University would profit from it.

Auburn has applied for two patents on sodium azide: one for the new liquid formulation of the chemical, which previously was marketed only in granular form, and the other for the chemical's soil-enhancement properties.

"As sodium azide decomposes in the soil, it breaks down into fertilizer and leaves the soil healthier than it was before the sodium azide was applied," Rodriguez-Kabana said.

Also, he said, while methyl bromide kills all nematodes and insects, both "good" and "bad" in the soil, sodium azide doesn't hurt beneficial nematodes and insects.

Rodriguez-Kabana's formulation isn't the only alternative to methyl bromide in development.

The EPA says five alternatives have been registered in the last four years, with others in the registration pipeline that may be approved and become commercially available. That would reduce the critical need for methyl bromide in 2005 and beyond, according to the EPA.

Nevertheless, supporters of methyl bromide use, including the American Farm Bureau Federation, haven't given up on easing the production ban, pressuring Congress and the Bush administration to intervene, with some effect. The United States has made a request to the United Nations for a two-year exemption to the methyl bromide phaseout, beginning in 2005.

Agriculture groups eligible for "critical use" exemptions to the phaseout can apply to EPA for an exemption, giving proof they have no alternative to methyl bromide use.

Top agriculture officials contend the phaseout of methyl bromide will lead to increased imports from China and Third World countries that can continue to use methyl bromide long after the U.S. and other advanced nations have halted its use. However, most industrialized nations will prohibit or already do prohibit the importation of food stuffs produced with methyl bromide.

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On the Net:

www.epa.gov/pesticides