Herbicide drift affects millions of crop acres across the nation every year, resulting in significant losses for many producers, lawsuits and tension among neighbors. A University of Kentucky weed scientist is helping grain producers find ways to minimize herbicide drift through his research and extension programs.
“It is in everybody’s best interest to minimize the off-target movement of herbicides,” said Travis Legleiter, an assistant extension professor in the UK College of Agriculture, Food and Environment. “Not only does it reduce our impact on the environment and maintain neighborly relations, but it assures the farmer is putting all of their investment in that product onto the field where it is intended to go.”
At the UK Grain and Forage Center of Excellence, Legleiter conducts research with UK interns and graduate students on ways producers can reduce herbicide drift. In a 2018 study, he found that the boom height of the sprayer and nozzle droplet size play a role in downwind drift.
“When we raised the boom from 24 inches to 48 inches, we found that our downwind drift potential tripled,” he said.
To reduce drift, many herbicide companies require producers to apply chemicals using larger nozzle droplet sizes. While this technique reduces drift, it also reduces herbicide coverage on the targeted weeds, which may reduce weed control. In a recent study, Legleiter and UK graduate student Madison Kramer evaluated different situations where larger nozzle droplet sizes might result in a loss of effective weed control, as well as other scenarios that could produce effective weed control.
“We found that producers can achieve excellent weed control when using systemic herbicides with large droplet nozzles, as long as they keep their weed densities down with a pre-emergent herbicide,” he said. “We want to show producers that they can use these larger nozzle sizes and still get adequate weed control.”
Legleiter shares the results of his research through extension meetings and presentations across Kentucky and the nation. In 2019, he presented his research during a United Soybean Board Take Action Webinar that strives to provide U.S. growers with the latest information on pesticide resistance management.
He also presents his findings and educates growers about drift during the Spray Clinic, which is part of UK’s Kentucky Agriculture Training School. The school’s programs offer producers information during hands-on field demonstrations. The Spray Clinic is one of the most well-attended events each year.
“We spend about 45 minutes with our spray table simply talking about droplet size, how to control droplet size and why it’s important for herbicide drift, he said. “We then go out to the plots and explain why droplet size and boom height are so critical in reducing drift using live demonstrations with bright pink dye that shows up on everything it touches downwind.”
During the winter, Legleiter travels across Kentucky bringing his spray table to county meetings. During the past two winters, he has educated about 750 farmers, spray applicators and consultants about ways to reduce drift through the meetings.
Going forward, Legleiter plans to create extension publications on herbicide nozzle selection and drift reduction and conduct additional research using a sprayer with pulse-width modulation, a newer technology to control droplet size and reduce herbicide drift.
— Katie Pratt, UK College of Agriculture