Soybean Rust Update October 6, 2015
Since my last update on September 21, 2015, Asiatic Soybean Rust has been confirmed on soybeans in 9 new counties in AL, 6 new counties in AR, 5 new counties in GA, and 38 new counties in MS. Rust has been confirmed on soybeans in most counties in MS. The closest find to Murphy remains DeKalb County, AL, at 115 miles. The rest of the state is closer to the confirmed find in Barnwell County, SC, which is about 140 miles from Charlotte, 360 miles from Elizabeth City, 185 miles from Fayetteville, 205 miles from Murphy, 240 miles from Raleigh, 295 miles from Washington, 210 miles from Wilmington, and 210 miles from Winston-Salem.
I do not consider these confirmations to signal any imminent threat to NC soybeans, so this will probably be the last soybean rust update for 2015. I still consider Steve Koenning’s (recently retired Extension Plant Pathologist) and my recommendation to not spray blooming soybeans that are more than 100 miles from confirmed presence of rust on soybeans to be a valid recommendation for most soybeans in NC. I do not recommend spraying for rust after stage R6 (full-sized beans in the top four nodes), since soybeans this mature will probably drop their leaves naturally before rust will cause many to drop prematurely. Check the label on the fungicide you prefer to use to see how late in the season that chemical may be sprayed.
The current status of rust in the continental US can be found anytime at http://sbr.ipmpipe.org.