Essential Oils Prove Natural Substitute for Methyl Bromide.

 Chemical Market Reporter; 3/22/1999; LANDAU, PETER

THE GROWING TREND toward natural in the flavors and fragrances market has taken a surprising turn. The US government's plan to phase out the toxic pesticide methyl bromide has led to novel research showing that essential oils may be effective biocides. Government scientists are testing benzaldehyde, which comes off peaches, as a substitute for methyl bromide in a range of applications.

The Agricultural Research Service, in conjunction with researchers in South Africa and Israel, has been testing natural chemicals for several years to determine their effectiveness as replacements for harmful man-made substances. Methyl bromide is a widely used pesticide said to be damaging to the earth's ozone layer.

Though natural compounds have been screened as pesticide replacements for at least a decade, the methyl bromide issue was put on the front burner only in the past five years. Methyl bromide, like chlorofluorocarbons and other materials harmful to the ozone layer, is scheduled to be phased out under the Montreal Protocol, a 1987 treaty.

BENZALDEHYDE RESEARCH

The use of these products was initially scheduled to end by 2001, but farmers protested that the time frame was unrealistic and Congress extended the deadline until 2005. Still, the use of methyl bromide in 2000 must be 25 percent less than it was in 1990, with usage decreasing quickly over the next few years.

Research began with natural benzaldehyde, but because of cost and quantity constraints, synthetic material is being used in experiments. Benzaldehyde is a component found in the essential oil of peaches. When a peach is in full bloom, as far as its flavor is concerned, benzaldehyde is the main volatile coming off it. The compound has an almond smell and is biodegradable, making it environmentally friendly.

"We're focusing on root pathogens," says Charles L. Wilson, a plant pathologist at the Agricultural Research Service's Appalachian Fruit Research Station in Kearneysville, W.Va. "We took the four major root pathogens and fumigated with benzaldehyde and got very good control in soil that had been infested with these pathogens."

Dr. Wilson's research team has developed a laboratory method to test the compound against the same pests that methyl bromide attacks. The tests proved effective and the team is applying the technology to the field, developing a soil delivery system that uses granules of activated charcoal saturated with the fragrant material.

"We're going to test some of our compounds in the field next year," says Dr. Wilson. "If these tests show promise, a commercialization path will be developed." The application of this natural pesticide in the marketplace could come within three to five years.

This research is relatively new to most players in the flavors and fragrances market. Though producers of essential oils are excited by the prospect of increased demand, they are unsure how it might affect availability. "BFGoodrich Kalama is following this situation closely," says a spokesperson for the only US chemical producer of benzaldehyde.

The research could also affect other essential oil compounds. Dr. Wilson notes that oils of wintergreen and clove may also prove useful. "In garlic, there's a compound that is a very good fungicide and bactericide," he says. "In terms of post-harvest, there is a garlic extract that works against the brown rot of peaches."

He adds, "We've been looking at a large number of the fragrance and essential oil compounds and combinations of them, and we're getting some synergistic combinations. There is a wealth of biocidal compounds that haven't been exploited, and we're also looking at plant materials from other countries".

"I don't know if there will be a kind of add-on value to some of these, but these are potentially pretty powerful pesticides that people haven't touched on. I think it's a very rich area in terms of the future."

Methyl bromide is used most extensively by strawberry growers in California and tomato growers in Florida. US agriculture is heavily dependent on the pesticide, and its overall market is massive. Its post-harvest market, to retard the decay of fruits and vegetables and extend their shelf life, is alone worth an estimated $25 million.

Dr. Wilson believes that his benzaldehyde research is only the "tip of the iceberg" for natural pesticides. He points to tighter regulations for synthetic compounds, which open up opportunity for natural compounds. "With the e.coli concern, there are opportunities to use natural compounds there," he adds.

Such pesticide applications are not just for food. In New Zealand, a natural compound has been developed to preserve lumber, and Dr. Wilson is looking at ways to incorporate natural compounds into packaging.

"You could have a self-fumigating package with natural volatiles," he notes. "I think that when you start talking about the market, you're talking about any need to control a fungus, a bacteria or any pest."

COPYRIGHT 1999 Schnell Publishing Company, Inc.