Soybean growers are urged to monitor their fields and contact their local extension agent or a local university plant diagnostic center if the appearance of Asian soybean rust is suspected.

The warning comes after the long-expected Asian soybean rust disease was discovered in the United States for the first time. It was found during mid-November in two plots on a research farm operated by Louisiana State University, near Baton Rouge, La.

The finding was announced after laboratory tests conducted by the USDA’s Animal & Plant Health Inspection Service confirmed the presence of the Phakopsora Pachyrhizi fungus, which causes soybean rust.

Soybean rust causes foliar lesions and premature defoliation. Crop yield losses can be as high as 90 percent if the disease is not quickly countered with appropriate fungicide applications. USDA officials and the United Soybean Board warn that early detection and management of rust are critical to minimizing the effects of the disease.

The appearance of soybean rust is expected to have minimal effect this season because most soybean plants have already been harvested. However, it is thought the disease can overwinter in the South, where kudzu provides a substitute host if soybean plants are not available.

Researchers believe the disease could then spread to other areas of the country next spring as the fungal spores travel on wind currents.

USDA officials have predicted for several years that soybean rust would eventually hit U.S. fields after the disease was detected in South America in 2004. With rust working its way…