Much of the U.S. is hotter and drier than normal reducing the likelihood of viable spore dispersal. However, USDA reports it is still intensifying scouting efforts in soybean plots, especially in the south.
Most of the soybean sentinel plots have been planted throughout the country with plants in some early planted plots starting to reach maturity. Scouting continues on kudzu patches from Florida to the north as far away as Nebraska. A recent limited survey of kudzu in Florida found no evidence of abundant infection or sporulation. Currently, there are no known reports of rust on commercially planted soybean in 2006.
Rust has been confirmed in five counties in Alabama, 11 in Florida, four in Georgia, and one in Texas. Recent rains in the some of the Southern states especially in Louisiana provide conditions for rust infection and development.
A report regarding Mexico indicated that rust had occurred earlier in the year (winter season seed production) before any commercial soybeans were planted in Mexico or the U.S. Spore trapping continues throughout the U.S. using both active and passive traps. Any positive spore trap information does not imply infection has taken place and plant samples are used exclusively for indicating positive rust occurrence as indicated on the soybean rust observation map.
Only time and weather patterns will tell whether Asian soybean rust moves into the Midwest this year and, so far, neither is talking, says Greg Shaner, Purdue University plant pathologist.
As much as agricultural researchers learned about the fungal disease in 2005, they still can't say if and when rust will infect the Corn Belt, Shaner said. He advised producers to keep a close eye on their fields and on weather reports this season.
"We've had so little experience with this disease in the United States that it's really difficult to say what our risk for rust infection is in the Midwest," Shaner says.
"I think most people feel that here in the Corn Belt we're not likely to see rust before soybeans flower in late July and August, and probably even later than that. Rust might not occur until the beans are beginning to fill the pods. In any case, we need to remain vigilant until the beans are pretty well developed. Then, if rust doesn't appear until that stage, there probably wouldn't be enough time for it to do much damage."