John Hammond's research is aimed at selling milk, just like any milk-mustachioed celebrity.

But not as a drink -- as an antiseptic.

Hammond, a research plant pathologist at the Beltsville Agricultural Research Center, is infecting tobacco plants with a common plant virus and a milk-treated virus to find out why milk can kill many of the maladies that damage everything from alfalfa to orchids.

Based on experiments that he began in July, the initial results are promising, he said.

Hammond said tobacco plants that he infected last summer by dabbing pure extract of tobacco mosaic virus on their leaves had about 40 times more lesions, or brown spots, than the plants infected with the milk-treated virus.

The tobacco leaves infected with the pure virus had 226 lesions per leaf. Those infected with the milk-treated virus had five lesions per leaf, he said.

"There's been evidence of this around for a long time, but no one has ever figured out why," he said.

Hammond's work is aimed at finding out why milk combats the spread of mechanically transmitted plant viruses, which cost farmers and greenhouse operators millions of dollars in lost crops each year.

Milk's antiseptic effects on plant life have been known in Europe for decades and were documented in the United States in a scientific report published in 1934, according to Hammond and other scientists. For years, Dutch farmers have instructed workers to dip their hands in milk before they harvest tomatoes and peppers, Hammond said.

Mechanically transmitted viruses -- such as tobacco mosaic -- are passed from plant to plant by hands and pruning shears, scientists have said.

"A gardener can pick up pruning shears to pluck a plant from a vine, and when he goes to the next plant, if the virus is on the shears, it's spread from one plant to the next," Hammond said.

Hammond said milk's possibilities as a preharvest treatment have never been explored because other preharvest treatments, such as alcohol, bleach and ammonium compounds, are available. But they dull the edge of pruning shears, corrode metal tools and have other drawbacks, Hammond said. "Commercial growers would love to have something easy to use," he said.

Hammond, assigned to the Floral and Nursery Plants Research Unit, said he learned about milk as a preharvest treatment a few years ago when a colleague suggested using it to clean an infectious virus off the walls of an oven-like growth chamber in his lab.

"That piqued my interest, and I've been curious about it ever since," Hammond said.

Hammond began his research in July with the help of Tressa Jones, 18, a senior at Eleanor Roosevelt High School in Greenbelt.

Jones, of Bowie, arranged to work as Hammond's intern because she wanted to fulfill a science requirement with a botany course, which her school does not offer.

"I think I've learned a lot," Jones said recently, after a morning spent documenting the damage done by the virus to 15 tobacco plants at the Beltsville greenhouse. "For one thing, I had no idea tobacco leaves grow as fast as they do."

It was the tobacco plant's rapid growth rate -- it can sprout three or four leaves in a week -- that prompted Hammond to use it in his experiments.

Tobacco has "long been considered the white rat" for plant experiments and is a common test subject, Hammond said.

He chose to infect them with tobacco mosaic virus because its lesions are easy to spot, and the virus is closely related to many of the roughly 1,000 mechanically transmitted viruses that damage commercial crops.

Hammond doesn't believe that the fat in milk plays a part in its power to protect plants, because dry, whole, low-fat and skim milk seem to perform equally, he said.

"At this point, we think it's a protein, but we're still trying to figure out which type of protein," he said.

He has a long way to go, according to Ian Matha, a chemist and milk expert at the University of Maryland Department of Animal Sciences.

Milk has eight major proteins and dozens of minor proteins, all complicated, Matha said.

"Milk is a very complicated fluid. There's an awful lot of things in it that could give it any given quality," he said. "[Hammond has] got his work cut out for him."

It could take weeks or months to test one protein. Hammond said he is aware of the work ahead. But, he added, research might lead to an extract -- a milk concentrate -- that could be sprayed on plants and gardening tools to prevent crop losses.

"It could be a lot of work, but I think it's something that is worth looking into," he said.

Pub Date: 12/03/98