Soy Checkoff, Partners Mark 10 Years of Tools Managing On-Farm Resistance

A green tractor drives a crop sprayer over a soybean field.

Like a silent thief, pest resistance creeps over the U.S. agricultural landscape threatening yield and forcing farmers to shift their best-laid pest resistance management plans as weeds, insects and diseases continue to outsmart the chemical control methods available. But you don’t have to face this resistance battle alone. The Take Action pesticide-resistance program is your ally to get ahead of yield-robbing pests every season.

Ten years ago, the soy checkoff led a consortium of industry groups to create an unbiased, science-based resistance education platform for farmers: Take Action. Land-grant university scientists, commodity groups including soy, corn, cotton, sorghum and wheat, as well as top ag chemical companies endorse the program’s resources. At first, Take Action’s educational platform focused on resistant weeds, with resources to better understand weed biology, cultural practices, herbicides and economics.

“Today, we focus on insect and fungicide resistance as well,” says Bill Johnson, Purdue University and Take Action program advisor. “The resources and information the program offers are more important today than ever before.”

Farmers across the country continue to fight the weed that, in 2016, the Weed Science Society of America identified as the most troublesome: Palmer amaranth. With confirmed resistance to multiple classes of herbicides, it’s an important limiting factor to farmer profitability.

“We have experience dealing with resistant rye grass and giant ragweed on our farm, and pigweed continues to be a threat,” says Susan Watkins, who farms in eastern Virginia. “But by changing chemistries, we seem to have it under control.”

Watkins, a soy checkoff farmer-leader, credits a blend of helpful resources from Take Action and careful management of the control methods available with helping her avoid significant impacts from resistance so far. “We address (pigweed) early with residual herbicides during burndown and using Extend technology for early-season control. We think it’s important to stay up on the latest research and recommendations based on checkoff research.”

Trent Irby, associate Extension professor at Mississippi State University, agrees that managing resistant weeds takes a multi-faceted approach. “Options range from the use of residual herbicides, to narrowing row spacing to help get a quicker canopy closure and reduce the window available for weed seed germination early in the season.”

How did we get here?

There are similarities in how resistance develops and what farmers should do to manage it across the pest spectrum of weeds, insects and pathogens, which cause diseases.

“Genetic variation exists across pest populations. Some strains (or individuals) might be resistant, or less sensitive to pesticides. Once an application is made, it will kill the sensitive strains and leave the resistant individuals to reproduce and increase in the population,” says Carl Bradley, Extension professor, plant pathology at the University of Kentucky.

What can we do?

To prevent fungicide resistance, farmers can choose varieties with a high level of foliar disease resistance. Fungicide applications using products containing multiple active ingredients with different modes of action and rotating chemistries through crop rotation are other effective tools.

“There are no weed resistant crops, so in a sense, choosing a disease-resistant variety and selecting chemistries with various modes of action places additional tools in your toolbox,” says Bradley.

The decision to use a fungicide, for example, is not always easy. Despite good scouting, keeping an eye on a reliable weather forecast and the use of a disease-resistant variety, good control decisions can still be difficult. This is especially true when dealing with new and emerging diseases, like target spot. Applying a fungicide prematurely can lead to additional exposure of fungal plant pathogen populations to fungicides, which can lead to the beginnings of fungicide resistance.

The soy checkoff will continue to invest in communicating the results of resistance research. Visit for the complete pesticide-resistance toolbox.

“Resistance is not going away. Farmers should use the free resources offered to tailor a management program addressing the specific pest issues on each of their farms,” concludes Johnson.

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