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RESISTANCE TO ORGANIC PESTICIDE DISCOVERED

by Staff Science Writers, The Daily Republican OnLine Newspaper

MADERA - Thomas H. Willey raises herbs and vegetables organically on 50 acres in Madera, California. When he needs a pesticide he utilizes a natural form produced by bacteria which grow in the soil. He dalls it the bacillus thuringiens is Bt pesticide. He has had to rsort to it at least three times in the last 10 years. Recently, he used it to protect a filed of carrots. Once he used it on basil, as well. Bt targets a handful of insects, is harmless to people and other animals, and breaks down quickly. When overused, resistance develops and the organic pesticied becomes useless.

Bt does so well that it has moved from backyards and a handful of organic farms to the mainstream as producers try to reduce the use of chemicals. But with its success has come increased worries that insects will become resistant to it.

That's especially true this year because of genetic engineering. More than one million acres of corn, cotton and potatoes that have been altered to produce Bt are being planted this spring.''Three cows are out of the barn,'' Willey told a forum held last week by the Agriculture Department, a rare event that joined organic growers, other farmers, university and corporate scientists and environmentalists.

Few disagreed that Bt resistance is a problem, though they differed on its scale and what regulators should do about it. Since 1985, two agricultural pests, the Indian meal moth and diamondback moth, have proved resistant in the field.

Ten other pests have shown resistance in laboratories. And Bt has been used for 30years on a small scale as a powder and spray. There are 500 species of mites and insects which have evolved built-in protections against synthetic pesticides that are widely used and have been a round for five decades.

Without plans to manage resistance, the Environmental Protection agency says, widespread resistance could develop within five years if the Bt producing crops are planted uniformly over large areas. That bothers environmentalists.

''Bts are a natural resource and a public good and should not be squandered,'' said Rebecca J. Goldburg, senior scientist at the Environmental Defense Fund in New York. That group and the union of Concerned Scientists want the government to slow down approvals of transgenic crops.

Monsanto Co., the St. Louis-based pesticide maker, developed the cotton and potato plants being grown commercially this year. Ciba-GeigyCorp., a Greensboro, N.C., pesticide company, developed the corn with Mycogen Corp. of San Diego. Environmentalist sources contacted by the Daily Republican say that once Bt is used up, the pesticide companies can fall back on new chemicals from their labs. The organic growers and other farmers can fall back on nothing.

That's nonsense, argue the companies, which say they wouldn't have invested hundreds of millions of dollars and years of research into a technology that would quickly become useless. For now, no one expects farmers to make a wholesale switch to the transgenic crops, even when the cost comes down and more become available.

San Joaquin Valley Corn growers remember the blight of the early1970s. They now regularly use a variety of hybrids to spread their risks.It will take a long time for all 80 million acres of corn to be planted in transgenic crops.

No more than 375,000 acres will be planted in Ciba's corn this year, said Jeffrey Stein, director of regulatory affairs for Ciba Seeds. That means there's time to work out strategies to fight resistance. He said after the forum, ''Farmers are going to experiment to figure out how little they need to plant to get the level of control they want.''

Most panelists agreed that the Agriculture Department needs to spend more on researching resistance problems and educating farmers. Farmers hotly debated whether they and their neighbors will be careful enough to use the new techniques wisely, rotate cropland keep areas where nonresistant insects will mate with resistant ones to keep resistance from spreading.

With that debate came suggestions that the EPA should require growers to follow plans for lowering resistance risk.




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