USDA plant pathologists confirmed a case of Asian soybean rust 5∞ north of the Equator. The find near Cali, Colombia, signals the advancement of spores toward the continental U.S.

“Rust is a devastating disease with the potential to cause enormous losses in annual U.S. soybean production, resulting in serious consequences for domestic industry, including the livestock sector,” says Ron Heck, a Perry, IA, soybean producer and chairman of the American Soybean Association.

Asian soybean rust has been Asia and Australia for decades. In 1996, it moved from Asia into Uganda and spread throughout Africa by 2001, the same year it was found in South America.

Based on weather models and past experience with other diseases, experts predict a natural introduction of soybean rust spores would most likely enter the U.S. through the southern tier of states along the Gulf of Mexico. The spores are easily transported in air currents and spread rapidly over wide distances.

Fungicide use in other countries has been effective in keeping soybean rust below the economic threshold of yield loss, Heck says. Early detection of soybean rust will be critical to minimizing spread of the disease, he says.