Asian soybean rust has been found in a soybean sentinel plot maintained by agricultural consultant Blaine Viator in St. Martin Parish near Coteau, according to LSU AgCenter plant pathologist Dr. Clayton Hollier.

The infected soybean plant was discovered on June 4 and verified by Patricia Bollich, an LSU AgCenter research technologist, by a field test, Hollier says.

“The significance is that this is the first sighting of Asian soybean rust on soybeans in Louisiana during 2009,” Hollier says. “The variety is unknown at this point, but the plant is in maturity group 5.

“Incidence and severity are low currently,” Hollier adds.

LSU AgCenter personnel have been monitoring for Asian soybean rust during 2009, and the pathogen was observed just after the beginning of the year on kudzu, the plant pathologist says.

“Several sites have retained rust on the kudzu during the year, especially the site at New Iberia,” Hollier says of the current situation.

Hollier says the site has developed spores as much as thousands of times greater than in past years and has been producing spores since late winter.

“Weather conditions have been favorable for development and spread of this disease,” Hollier says. “We recommend scouting, especially in southern and central Louisiana and in southern Mississippi.”

Kudzu is one of the host plants for Asian soybean rust, meaning the disease can survive on kudzu and spread to soybeans, says Boyd Padgett, an LSU AgCenter plant pathologist. If not caught early – when the disease spreads more slowly – rust can spread rapidly and destroy entire soybean fields, he says.

Asian soybean rust was first discovered in the U.S. in 2004. Although it’s been known to exist since the early part of the 20th century, it was largely confined to Asia until recently – when it spread to Africa and then on to South America around 2000.

Since its initial discovery in south Louisiana in 2004, where its wind-borne spores are thought to have come in on storm winds that summer, Asian soybean rust has been seen in and on soybeans in a variety of southern states, including Florida, Georgia, Alabama, Mississippi and Texas.