It has now become a ritual in late summer and early fall to keep a lookout on Asiatic Soybean Rust and if and when it will show up on U.S. soybeans. Well, N.C. State University soybean specialist Jim Dunphy and plant pathologist Steve Koenning report ASR has been detected for the first time this year on soybeans in the continental U.S.
The report of ASR comes from Gadsden County Florida, which is located in the state's panhandle. One leaf out of 100 was found to be infected in the Florida sentinel plot. A sentinel plot is one of many plots planted around the country, intentionally designed to be susceptible to ASR. These sentinel plots serve as an early warning tool for the disease.
The infected soybeans are a mid group V variety planted on April 11 and was in stage R6 (with full sized pods in the top of the plant) when ASR was discovered on the plants during the week of August 31.
Koenning and Dunphy noted weather conditions were favorable in North Carolina for ASR at the time but that "it is still considered too hot in Florida for rust to thrive, so it is not likely that this new find will increase the threat to North Carolina's soybean crop appreciably."
Tim Britton who works the Johnston County, N.C., Cooperative Extension Service notes tropical storms can provide transport for rust. He also notes the national forecast is for an above average tropical storm season. Hurricane Irene and several other storms currently spinning out in the Atlantic are evidence of this.
"Watch for tropical storm events that bring moisture from the south," Britton notes. "We learned last year that rust can and will make large jumps distance wise over a relatively short period of time."
To follow the progress of Asiatic Soybean Rust in the U.S., visit the Integrated Pest Management web page dedicated to soybean rust http://sbr.ipmpipe.org/cgi-bin/sbr/public.cgi.