WASHINGTON -- Government scientists have found that the harmless natural oil that gives peaches their perfume also kills fungus and other pests in the soil and could replace methyl bromide, a widely used pesticide that is toxic to people and also damages the planet's protective ozone layer.
The peachy compound, called benzaldehyde, is manufactured synthetically. It is already used commercially in perfumes, flavorings, drugs and dyes, as are many similar oils, such as those distilled from lemon and peppermint.
Scientists at the Agricultural Research Service, along with colleagues in South Africa and Israel, have been screening these natural chemicals for several years to see if they can be substituted for more dangerous man-made compounds. The essence of peach looks like an especially promising candidate, said Charles Wilson, a plant pathologist at the agency's Appalachian Fruit Research Station in Kearneysville, W.Va.
His team developed a laboratory method for testing the extract against some of the most important pests that methyl bromide attacks, and when it proved effective, they developed a new approach for applying benzaldehyde to soil using granules of activated charcoal saturated with the fragrant chemical.
If field tests prove successful, the scientists hope, it could be a significant breakthrough in ridding the world of methyl bromide. Like other chemicals such as CFCs, or chlorofluorocarbons, methyl bromide is supposed to be phased out under the Montreal Protocol, a 1987 treaty to protect the ozone layer. The ozone layer is important because it shields the Earth from the sun's ultraviolet rays, which cause cancer and other environmental harm.
Last year, bowing to protests by farmers who said that it was impossible for the United States to end methyl bromide use as scheduled in 2001, Congress gave the industry until 2005 to do so.
Wilson said in an interview that he doubted that any single compound, like the peach oil, would be a "magic bullet" to replace methyl bromide. But he said he was optimistic that combinations of naturally occurring chemicals, along with other changes in farming methods, would provide important benefits.
"There is such a broad range of these things that are in nature already, and there has not been that much effort yet in trying to fish them out," he said. "The synthetic compounds were so powerful that we stopped looking for natural pesticides."
Pub Date: 3/14/99