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Soybean Plant Health

Asian Soybean Rust - Latest Information for Wisconsin

Asian Soybean Rust

Asian soybean rust is caused by the fungus Phakospora pachyrhizi. The soybean rust pathogen has been moving progressively westward from its center of origin in China and has now reach North America. There is much speculation and apprehension on how soybean rust will develop and impact soybean production in the U.S. The reality of the situation is that soybean rust has been a devastating disease in many parts of the world. Thus, it is prudent that we respect its potential to reduce yield, and be prepared to manage it each season.

Asian soybean rust developing in a soybean field. Photo credit: Craig Grau

Monitoring rust with sentinel plots

Early symptoms of rust on a lower leaf along the leaf veins. Click on image to view larger version.

Soybean rust is monitored in sentinel plots established in Buffalo, Chippewa, Clark, Columbia, Dane, Dodge, Grant, Green Lake, Jefferson, La Crosse, Marinette, Monroe, Outagamie, Pierce, Polk, Rock, Sheboygan, and Wood counties. Wisconsin will continue to monitor soybean rust sentinel plots through the combined efforts of county extension agents, agriculture research station staff, and UW-Madison campus research staff.

Goals of the sentinel plot network include identification of spore-producing areas and collection of data for research. However, the primary goal is detection of soybean rust at low levels and providing an early warning system for soybean producers. Over 30 states have joined this sentinel plot network that utilizes trained observers to look for signs and symptoms of rust on soybean, dry beans and kudzu.

Most Wisconsin soybean growers will have a sentinel plot within their county or will border a county with a sentinel plot. Results of these sentinel plots are disseminated through the USDA Pest Information Platform for Extension and Education (PIPE) website.

Check the USDA PIPE rust maps frequently. Click on the state of Wisconsin for advisories.

Changes in Soybean Rust Fungicide Status
Since 2005, Wisconsin and other soybean producing states had an unprecedented number of fungicides approved by EPA through the Section 18 Emergency Exemption process for only the control of soybean rust on soybean. While many of these products have since been approved for a Section 3 label, indicating that EPA has approved their use throughout the U.S., others have not, and their Section 18 labels have expired as of November 10, 2007.

See Fungicides for Soybean Rust Available in Wisconsin for a list of Section 3 and Section 18 fungicides.

Publications

Soybean Rust Management in Wisconsin
A two-page bulletin from the UW Nutrient and Pest Management program, UW Integrated Pest Management, and UW-Extension, with guidelines and a decision tree for rust fungicide use...view pdf»

Soybean Rust and Crop Insurance
A two-page brochure on insurance claims and Asian soybean rust, Soybean Rust, Crop Insurance, and You, from the USDA Risk Management Agency.
View publication (pdf)»

Using Foliar Fungicides to Manage Soybean Rust is a comprehensive, online reference guide, covering the factors involved in making fungicide spray decisions, choosing fungicides, and strategies for fungicide application. Several new chapters added for 2008. View online in pdf format»

Fungicide Application Techniques - powerpoint presentation
Chris Boerboom, UW Extension Weed Science
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More publications and information sources on rust »

Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: University of Wisconsin-Madison, Departments of Agronomy, Entomology, and Plant Pathology at  www.plantpath.wisc.edu/soyhealth.

11/08