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Research Highlights
Georgia’s Sentinel Plots Catch Early Appearance of Asian Soybean Rust

Photo: Bob Kemerait

By Laura Temple

Following a mild winter in 2019-2020, ASR made its earliest appearance in Georgia since sentinel plot monitoring began. Sentinel plot monitoring, supported by the Georgia Agricultural Commodity Commission for Soybeans, alerted southeastern soybean farmers and provided information to help them make treatment decisions.

“Our plots give growers a heads up about where and when ASR is in Georgia,” explains Bob Kemerait, a plant pathology professor and Extension specialist with the University of Georgia. “This information helps them determine if a well-timed fungicide application is needed or not.”

Kemerait says research shows that fungicides applied based on early warnings may protect soybean yields by 25 bu/A or more. Some years, fungicide applications make sense, while other years, fungicides may not be necessary.

Georgia’s sentinel plots include patches of kudzu, an overwintering host for ASR, scattered throughout the state. Also, soybean plots containing varieties of three different maturity groups are planted early at Georgia’s experiment stations as sentinel plots. All plots are monitored weekly from April through September. Leaves collected from the kudzu and soybeans come into a lab where they are examined closely under a microscope.

Photo: Bob Kemerait

Once ASR is detected, information about what county it was found in and the potential for its spread is shared with county Extension agents, added to the ASR map and posted on Twitter. Kemerait says soybean farmers in neighboring states also benefit from watching Georgia’s monitoring to know when ASR is moving their direction.

“The process follows a plan that was implemented when ASR showed up in the U.S., and it’s been so effective we are still using it 16 years later,” he adds. “Our soybean growers invest in this program every year so they are not surprised by this and other diseases.”

In addition to ASR, Kemerait notes that sentinel plots are monitored for other soybean diseases, including Cercospora leaf blight, frogeye leaf spot, anthracnose and more.

“We appreciate soybean grower trust in Extension to provide this information every year,” he continues. “This investment pays off for the growers by allowing them to make timely fungicide applications as appropriate, or to delay applications until needed each year, based on what we find in the sentinel plots.”

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.