Promising lab results by researchers at Washington State University (WSU) and the U.S. Department of Agriculture's Agricultural Research Service (USDA-ARS) show the herbicide glyphosate has activity in suppressing Asian soybean rust.

WSU has applied for U.S. and international patent protection, which will be published soon. WSU, through its Washington State Research Foundation, intends to license this intellectual property broadly. The foundation already has reached a preliminary agreement with Monsanto Co., the producer of glyphosate-based Roundup agricultural herbicides.

The research was funded by a USDA Biotechnology Risk Assessment Grant and WSU.

In the process of studying fungal pathogens in wheat, Kim Kidwell, a spring wheat breeder; graduate student Jamie Baley; and Tim Paulitz, a plant pathologist with the USDA-ARS, Pullman, found that glyphosate suppressed Asian soy rust in preliminary greenhouse trials when glyphosate-resistant soybeans were treated. The greenhouse trials were conducted at the USDA-ARS Fort Detrick, Md., location where the USDA has facilities to work with foreign pathogens under bio-containment.

"These early findings are promising, however, further research must be conducted to validate the results under field use conditions," said R. James Cook, plant pathologist and interim dean of WSU's College of Agricultural, Human, and Natural Resource Sciences. "If these results translate to the field, this could provide another tool to soybean producers in combating Asian soy rust." He also noted this finding would not have been possible without the biotechnological advances in plant breeding and plant pathology of the past several years.

Asian soy rust is a foliage disease caused by an airborne fungus that can cause serious yield losses. The USDA confirmed the first detection of the pathogen in the continental United States last fall.

Jerry Hjelle, vice president for Monsanto Worldwide Regulatory Affairs, cautioned that the data is preliminary.

"We will be carefully analyzing the research from WSU and gathering further information to determine product efficacy and use on Roundup Ready Soybeans," said Hjelle. "At this time, we strongly recommend soybean producers use fungicides labeled for treatment of Asian soybean rust."

Glyphosate herbicides are not currently registered or labeled to protect against or control Asian soybean rust and existing residue tolerances may not be adequate for this potential use. It is a violation of federal law to use a glyphosate pesticide in a manner inconsistent with its labeling.

"This discovery embodies WSU's mission and values as Washington's land-grant university," said Jim Petersen, WSU vice provost for research. "Through its technology transfer system and the support provided by the research foundation, WSU research programs are advancing the nation's economy and ensuring the global competitiveness of agricultural products."