Soybean crops at risk due to rain

By Vershal Hogan (Contact) | The Natchez Democrat

Published Monday, July 9, 2007

VIDALIA — Concordia Parish’s risk for the deadly soybean rust will increase over the next few weeks, agriculture experts say.

Soybean rust has already spread beyond in southern Louisiana, but the devastating crop disease has not made its way into the Miss-Lou.

The U.S. Department of Agriculture reported in late June the fungus had been found in two patches in both Rapides and Avoyelles parishes, and now it has been found in Assumption Parish in southeast Louisiana, according to the USDA.

The chances of rust moving north in the next few weeks are increased due to regular rainfall, the USDA Pest Information Platform for Extension and Education reported.

Asian soybean rust causes plants to drop their leaves before they are mature and can affect the number and quality of beans in pods.

Rust has also been found in kudzu in areas surrounding the infected plots.

Because it needs living tissue to survive, rust often makes it through the winter by using kudzu — one of more than 80 plants the parasitic spores infect — as a host.

The disease, which can be detected in early stages when lesions form near leaf veins, needs wet conditions with temperatures between 59 and 82 degrees Fahrenheit.

In intermediate stages the lesions turn red and brown, and in later stages cream-colored, egg-shaped pustules filled with spores form on the leaves.

Rust spores are spread by high winds, and some speculate they were brought to the continental United States from South America by a hurricane in 2004 — it was first found in Louisiana — but the disease has been confirmed in Hawaii since 1994.

Rust resistant soybean varieties have been developed, and it can be managed with fungicides.

For more information about the spread of rust, visit the USDA soybean rust Web site www.sbrusa.net.