Asiatic Soybean Rust has been found in Tift County, Georgia. Jim Dunphy, N.C. State University Extension soybean specialist, and Steve Koenning, NCSU Extension plant pathologist, noted the recent discovery in their Soybean Rust Update for August 21, 2012. That puts the ASR closer to soybeans in the eastern part of North Carolina than has otherwise been found this year.
It locates the ASR within approximately 300 miles from Charlotte, 535 miles from Elizabeth City, 360 miles from Fayetteville, 185 miles from Murphy, 405 miles from Raleigh, 375 miles from Wilmington, 470 miles from Washington, and 370 miles from Winston-Salem, North Carolina.
Tift County is in the South Central section of Georgia, so obviously this discovery puts ASR discovery much closer to South Carolina, as well. ASR has been found in Georgia this year at sites within about 50 miles of farming communities in southern South Carolina. However, recommendations for ASR treatment in South Carolina do not typically fall within the coverage area for Dunphy and Koenning, so it is advisable for South Carolina farmers to contact their local Extension agents for recommendations in their areas.
As for North Carolina, Dunphy and Koenning note they do not recommend spraying soybeans with a fungicide to control ASR if they are not yet blooming, if they are blooming but the rust has not been confirmed within 100 miles, or if full-sized seeds are present in the top of the plant (stage R6).
They note pre-bloom applications have seldom improved yields and that repeated applications will likely be needed to provide season-long protection against rust. The higher labeled rates tend to provide more days of prevention, and may thus require fewer applications.
The triazole fungicides, alone or in combination with a strobilurin fungicide, they note, will probably provide better prevention of rust than a strobilurin alone. Be sure to check the fungicide label, they say, to see how many times it may be used in a season.
Growers can stay up to date with ASR sightings at the Integrated Pest Management ASR alert page at sbr.ipmpipe.org/cgi-bin/sbr/public.cgi.