New types of pesticides have helped cut the amount of chemicals applied to farmers' fields, a weed scientist said.

Ford Baldwin, who works for the Cooperative Extension Service, University of Arkansas, said pesticide use has changed a lot over the last two decades."The early 1970s were a boom time for herbicide development," Mr. Baldwin said this week. "Herbicides were easy to apply and cheaper and more reliable than hand labor.

"Then in the late '70s, commodity prices went down and the cost of producing a crop went way up. Farming became less profitable. We looked at ways to cut input costs," he said.

Mr. Baldwin said University of Arkansas researchers are looking at different types of fungi for control of weeds, insects and plant diseases. Chemical companies are also exploring ways to make their products environmentally friendly, he said.

"If you look at the herbicides that are coming out now, the application rates are in grams per acre instead of pounds per acre," he said. "The new products have very low toxicity. Many of them work on enzymes in the plants that don't even exist in animals. They're less toxic than table salt."

Mr. Baldwin and others at UA found that, by targeting herbicides to specific weeds and timing the applications right, herbicides could sometimes be applied at one-fourth the manufacturer's recommended rate while still providing good weed control.

"Arkansas was the first state to recommend rates lower than those on the product label," Mr. Baldwin said. "Now, a couple of other states are doing it, and there's tremendous interest in other states."

People are looking for alternatives to pesticides for several reasons. Increased government regulation has led to fewer chemical companies and fewer products being developed.

With fewer new products on the market, farmers have had to rely on what has worked in the past, and that's led to problems. Weeds, insects and plant diseases can become resistant to pesticides that are used over and over.

Reducing the rate of pesticide application slows the buildup of resistance, but it can't solve the problem. Scientists and farmers are searching for non- traditional solutions.

Extension Service entomologist Don Johnson said UA scientists are working to incorporate a gene into cotton plants that makes the plants less susceptible to bollworms.

"It's called Bt cotton," Mr. Johnson said. "Bt stands for Bacillus thuriengensis, a bacterium. Bt kills by releasing a toxin that the plant produces."

Mr. Baldwin and other UA scientists have sought a solution to herbicide- resistant barnyard grass in rice. In recent years, the weed has become resistant to some of the standard weed-control chemicals.