Research Highlights

Research Highlights
Promotion board continues to fund rust monitoring system

By Kentucky Soybean Board

Most Kentucky Soybean farmers have never seen Asian Soybean Rust in the field, and that’s a good thing. This fungus was first found in the United States in 2004, in Louisiana. It has since spread to heavy coverage in Alabama, Mississippi, Georgia and South Carolina. It has been found to a lesser degree in Tennessee and Arkansas, with a few isolated counties in Virginia, Maryland and Illinois report­ing small amounts of Soybean Rust (SBR). In 2012, SBR was found in Caldwell and Muhlenberg counties in Kentucky. The fungus was found in late September, far enough into the grow­ing season that it had no adverse effects on the crop.

Don Hershman, Ph.D., is an Extension Plant Pathologist stationed at the University of Kentucky Research and Education Center in Princeton. He oversees the SBR Monitoring System and has studied the fungus since its discovery in the U.S.

“We have learned so much about rust since the Promotion Board started funding this project back in 2005,” he said in a recent interview. “When this disease first came from Brazil, we had never seen it. We started this project with over 1,000 sentinel plots in the U.S. and Canada, and since that time we’ve been able to scale back dramatically because of the things we’ve learned from the data. We know, for instance, that rust will not overwinter here in Kentucky. It just gets too cold. It tends to overwinter in kudzu, which is all over in the Deep South.”

Asian Soybean Rust in the field. Photo courtesy of Dr. Don Hershman

“Though to-date, rust has only caused damage in Georgia, Florida, Mississippi and Alabama, we can’t let our guard down,” Hershman said. “This year, for instance, we had a wet spring. The ‘perfect storm,’ if you will, for rust to spread to Kentucky from down south is a trio of factors. A significant amount of rust overwintered in the Deep South because of the mild tem­peratures. That’s one. They had a lot of moisture in Louisiana and Mississippi in April and May. That’s two. The third factor that could drive rust into Kentucky’s soybean fields is a tropical storm which can carry live spores in its clouds.”

Hershman said that spores can survive in these storms and move as much as 1,000 miles in a single day, meaning that if conditions are right, we could have SBR in Kentucky in July. The severe drought kept rust at bay in 2012, because the fun­gus is highly sensitive to ultraviolet radiation.

“An outbreak of soybean rust in Kentucky is not a matter of ‘if,’” Hershman said. “It’s a matter of ‘when.’” When an outbreak occurs, proper and timely spraying with an appropri­ate fungicide can kill the rust and save the crop. The Kentucky Soybean Promotion Board funds the Soybean Rust Alert Sys­tem for famers in the Commonwealth. It’s a service provided free to farmers – all they need to do is contact Rae Wagoner at the Kentucky Soybean Office (800) 232-6769 or via email and ask to be put on either the voice notification list or the text message list. Notifications are sent out weekly from June through October, advising that the risk level for soybean rust is green (no risk), yellow (moderate risk) or red (high risk, action required.)

Published: Dec 17, 2019

The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.