Cornell weed scientist Russell Hahn was working toward his master's degree at the University of Nebraska in the mid-1960s when he filled in for several months for a Cooperative Extension weed specialist who had had a heart attack. That's when Hahn knew what he wanted his lifework to be.

Now, for more than quarter-century of careful research on reduced-risk weed management that New York's farmers have come to trust, Hahn, Cornell professor of weed science who has been working at the university since 1974, has received an "Excellence in IPM Award" from the New York State Integrated Pest Management (IPM) Program.

Both conventional and organic growers find that weeds are one of their most daunting problems. It is hard to develop "soft" pesticides or find natural enemies for weeds because most will attack only one species, and once you get rid of one weed, another takes its place. So Hahn's research has zoned in on how farmers can reduce herbicide use, often steeply, using IPM.

In fact, Hahn has shown that many farmers could cut their herbicide applications by one-third to one-half by eliminating pre-emergence herbicide applications in favor of total post-emergence weed control programs. These programs allow farmers time to scout for weeds ahead of time so they can better choose pesticides. Yet while these tactics can save time and money, they require a basic knowledge of weed identification and weed life cycles.

"If my prayers could be answered, it would be for growers, whether conventional or organic, to know their weed identification and basic plant biology," Hahn says. "And then to get the planting date, seeding rate, nutrient management and other cultural practices right. The package has to go together."

"Many farmers decide to attend a winter crops meeting based on whether Russ Hahn is on the program," says colleague Gary Bergstrom, Cornell professor of plant pathology. "Russ is the face of Cornell Cooperative Extension to many of the state's field crop producers. It can be a little daunting to follow him as a speaker."

Mary Woodsen is a science writer with Cornell Cooperative Extension's Integrated Pest Management Program.