February 1, 2006

Asian Soybean Rust off to an earlier start in US than in 2005

Far greater amounts of Asian soybean rust appear to have overwintered in the U.S. Deep South this season, with the latest discovery made in Georgia on Monday, thus confirming the disease in 12 counties spread across 3 states just one month into 2006.

The latest outbreak was revealed to the US Department of Agriculture by University of Georgia researcher Layla Sconyers, who reported discovery of the airborne fungus present in a kudzu plant in a Grady County alley.

"This particular kudzu was located behind a building, protected from the weather in downtown Cairo, Ga., near the Georgia/Florida border," she told the agency's official soybean rust website. "The rust was found on what appeared to be older leaves that had survived through the cold temperatures, due to protection from the building."

The first detection of soybean rust in Georgia during 2005 didn't come until April. Rust has also been found in one county of Alabama, fully five months earlier than was the case in 2005. Florida has also reported 10 rust-positive counties.

"Scouting efforts are under way in all states of the Deep South and in Texas," said the USDA in a national rust commentary.

Kudzu is a common broadleaf weed found throughout the south-eastern quadrant of the US and is an alternative host of soybean rust. Researchers suggest that the extent to which frosts cause "kudzu dieback" each winter could become a key factor in determining the annual dispersal of the disease among the US soybean crop.

"There is currently nearly 100 percent dieback for Texas, except for the coastal areas; all but the coastal areas of Louisiana, most of Alabama, most of Georgia and the Florida panhandle," said USDA in a weekly update.

The fungus, which causes premature defoliation of plants and severe yield losses, was found in 138 counties of Alabama, Florida, Georgia, Kentucky, Louisiana, Mississippi, Texas, and the Carolinas in 2005.