Potential pesticide nothing to sneeze at Pepper might help nursery plants

December 02, 1997|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

James Locke and John Bowers think they might have found a pesticide for the future.


A pepper extract they began experimenting with last year shows promise as a pesticide to treat soils and help grow nursery plants, according to the two plant pathologists at the Beltsville Agricultural Research Center.

Bowers began experimenting with a pepper extract that also contains mustard in the summer of 1996, when he found some left over in his lab from a previous experiment.

"It was a shot in the dark. It just happened to be there and it worked," said Bowers, 44, of Laurel.

The discovery might be important because scientists have been searching for years for a replacement for methyl bromide, a ubiquitous but toxic compound slated to be banned in the United States by 2001.

They say the pepper extract is not likely to replace methyl bromide completely.

But its discovery is a step in the right direction and may one day help greenhouse operators who raise nursery and ornamental plants, they say.

Locke and Bowers began searching in 1994 for something that would kill harmful fungus in soils, help grow nursery crops and prove environmentally safe.

The two scientists, assigned to Beltsville's Floral and Nursery Plants Research Unit, began looking at garden herbs and spices because scientists have known for decades that some of them have chemicals that could kill various types of fungus, weeds and microscopic worms.

Trial and error

They tried the oil extracted from the neem tree, a tree grown in India, where the oil is used as a skin ointment.

But they found that only increased the level of fungus in soils.

They checked basil, but found it did little to kill fungus.

Clove oil also proved ineffective in its present form.

But last summer, Bowers picked up pepper mixed with a mustard extract -- marketed for about two years as a household insecticide -- and began checking it.

First, he mixed the extract with water, diluting it so that the solution was about 95 percent water and 5 percent extract.

He applied it to soil potted in his lab and greenhouses and let the soil lie fallow for a few weeks.

Then both scientists examined the soils, counting the amount of fungus and microscopic worms that live there to see if the extract killed them.

Unexpected results

What they found surprised them: The active ingredients in the pepper were effective in killing fusarium, a particularly nasty fungus that wilts carnations, chrysanthemums and other ornamental flowers.

"It was pretty much unexpected," said Locke, 51, of Silver Spring.

Locke and Bowers have been testing pepper ever since, and the signs are promising, they say.

Their tests show that soils laced with the extract were more hospitable for melons grown in a greenhouse behind their lab.

They say their tests, conducted over the past two years, also have shown that pepper combats rihizoctonia and verticillium, two types of fungus that together can decimate a wide variety of crops, trees, shrubs and other plant life.

They think pepper may work as a pesticide for the ornamental crop industry, which grows flowers and shrubs in greenhouses.

But whether it would work for field crops -- such as tomatoes and strawberries, which also depend on methyl bromide -- is harder to determine, Bowers said.

"There's still a lot of work that has to be done," he said.

Phasing out methyl bromide

The findings are important because methyl bromide, one of the world's most widely used pesticides, is being phased out.

Farmers nationwide apply about 55 million pounds of it to their soil each year.

It's been used since the 1940s and is effective at killing a variety of weeds, microscopic worms and types of fungus that attack the roots of crops, said Kenneth Vick, a methyl bromide expert for the U.S. Department of Agriculture.

But it's scheduled to be phased out by the Environmental Protection Agency in 2001 as part of the Clean Air Act, because scientists say it depletes the ozone layer, Vick said.

Agricultural groups are fighting the ban in Congress.

But as the law stands, it is slated to take effect Jan. 1, 2001, officials say.

"The ban is really a political hot potato right now," Locke said.

Pub Date: 12/02/97

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