September 29, 2006
Asian soybean rust approaching US state Virginia
Asian soybean rust continues to move towards northern US, reported in a half-dozen new counties of North Carolina, and an additional county of Georgia, bringing the total number infected thus far in 2006 to 78, across the country.
"Rust was detected in the sentinel plots in Scotland, Lenoir, and Edgecombe Counties, and in surveys in Craven, Jones, and Beaufort Counties," North Carolina State University Plant Pathologist Steve Koenning reported to USDA Thursday (Sep 28). "Rust incidence in all locations was low. In most cases it is too late to apply fungicides to soybean, and the chances of measurable yield loss from soybean rust are minimal."
The Edgecombe County outbreak represents the most northerly discovery of rust in the US this season, occurring approximately 40 miles south of the Virginia state line.
Asian soybean rust was also confirmed in two commercial soybean fields in Washington County, Georgia, this week.
"These are the first documented cases of rust in commercial soybeans this growing season in Georgia," said University of Georgia plant pathologist Layla Sconyers.
The airborne fungus has now been found infecting soybeans and kudzu in a total of eight states, including Alabama, Georgia, Florida, Louisiana, Mississippi, North Carolina, South Carolina and Texas.
An infection forecast updated Wednesday by USDA said fair weather which had been dominating the Southeast will soon give way to clouds, shifting winds and light showers of a passing cold front that will heighten the previously-low risk of new rust development.
"A wedge of increased risk is expected in eastern Texas and northern Louisiana due to a short period of southerly winds," said the agency. "Risk will remain high in southern Florida, due to showers and light breezes."
The plant pathogen flourishes in warm, damp, overcast weather, causing premature defoliation of immature soybeans and sometimes major yield losses, unless immediately countered with chemical fungicides.
