Source: University of Illinois

When soybean rust first appeared in the United States in late 2004, many producers feared devastating yield losses similar to losses experienced in other parts of the world. In response to this threat, researchers have been evaluating USDA soybean germplasm accessions for resistance to this fungus, and a recent report in Crop Science identifies some of these resistant sources.

"Our goal was to determine which of the soybean germplasm accessions were resistant in the United States and whether they were resistant throughout the southern United States," explained David Walker, USDA-ARS scientist and assistant professor in the University of Illinois' Department of Crop Sciences. "Early on, we didn't know anything about the uniformity of the fungus populations in the mid-southern and southeastern states. It's tricky because the threat of this fungus is very dependent on weather conditions."

For example, Walker said this fungus reproduces more rapidly when temperatures are moderate and where there's abundant rainfall and heavy dew, causing spores to germinate and infect plants. The spores can move by wind and travel hundreds of miles to start a new infection, making it hard to contain.

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