Soybean rust was discovered in new counties in Georgia and Florida, two states already heavily infected by the disease, the US Agriculture Department said on its rust-monitoring web site.
A stationary front in the Midwest and Hurricane Katrina churning through the Gulf of Mexico could spread soyarust spores further north into southern Missouri, the Ohio River Valley and the Mid-Atlantic states over the weekend, the USDA said.
In Florida, a new case of the fungus was found in a sentinel plot in Calhoun County. That makes a total of 19 counties in Florida with Soyabean rust so far this year, and more are expected to be infected.
In Georgia, rust was found in Oconee County in a sentinel plot, the USDA said, boosting the number of infected Georgia counties to 12. The sentinel plot was incorrectly reported earlier this week to be in neighbouring Clarke County.