University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

April 7, 2006

Nebraska soybean rust forecast for 2006

This year’s mild winter will impact the potential for soybean rust in 2006. This will be the third season for soybean rust is in the United States. It was first detected in the United States in November 2004 and had no impact on production. During the 2005 season soybean rust developed in only five southeastern states and had very limited impact on production. Late in the season it spread west into Texas and additional states in the southeast. The farthest north soybean rust was found was in Tennessee in November 2005. With this limited spread in 2005 the big question is “Will soybean rust move more in 2006?” Following are a few points that should be considered as we evaluate the risk for the Nebraska soybean crop in 2006.

One key point that should be considered is how far south the frost line extended into areas where soybean rust could overwinter. As rust is an obligate parasite (needs a living plant to survive the winter), this is a critical point. As of April 5 soybean rust has been confirmed at many more locations than in 2005. So far there have been several sites identified in Alabama and Florida kudzu patches. Surveys of volunteer soybeans in southern Texas have not confirmed active soybean rust, but Mexico has. Mexico and Texas are important to Nebraska because there is a consistent air current which moves north from Mexico and Texas over the Great Plains states. This air current could move soybean rust north as it does each year with wheat rusts.

Nebraska’s location in the central United States allows us to utilize states to the south and east as sentinel fields. Once again this year the soybean rust sentinel plot network will be used. This system is being funded by USDA and your soybean checkoff. The sentinel plots of early planted soybeans will be frequently scouted. We will have 20 to 30 sentinel plots throughout Nebraska, many of which will be coordinated by University of Nebraska-Lincoln extension educators. All sentinel plot observations will be entered into the USDA Soybean Rust Web site which is linked on the front page of the UNL Soybean Rust Web site.

The increase in the number of inoculum sources for soybean rust at this time of year over last year increases the potential for soybean rust to be more of a problem for production this year. The reality of the situation is that no one knows exactly what soybean rust will do this year. Staying aware of where soybean rust is developing throughout the growing season will be critical to managing the disease.

Two University of Nebraska-Lincoln resources can provide real-time information on soybean rust to help you better plan and address developing problems. The UNL Soybean Rust Web site (soybeanrust.unl.eud) is a focused site which provides links to all pertinent Web sites for managing soybean rust in Nebraska. Throughout the growing season the soybean rust phone hotline, which is a toll-free recorded message, will be updated as needed with soybean rust locations, conditions and management recommendations. The hot-line number is (877) NebRust or (877) 632-7878 and is funded by the Nebraska Soybean Board.

Loren J. Giesler
Extension Plant Pathologist, Lincoln

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Copyright 2006 by the University of Nebraska Board of Regents. All rights reserved.
Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.
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