Soybean Rust Update Oct. 17, 2016

— Written By and last updated by

from Jim Dunphy, Crop Science Extension Specialist (Soybeans)

and Lindsey Thiessen, Extension Plant Pathologist

Asiatic Soybean Rust has been found on some leaves from research plots at the Pee Dee Research and Extension Center in Florence County, SC. This puts confirmed rust closer to most NC counties than previously confirmed. This find is approximately 100 miles from Charlotte, 245 miles from Elizabeth City, 80 miles from Fayetteville, 55 miles from Lumberton, 250 miles from Murphy, 130 miles from Raleigh, 180 miles from Washington, 100 miles from Wilmington, and 140 miles from Winston-Salem.

Folks who are scouting soybeans that still have green leaves should be alert for signs of rust, especially on the back side of leaves in the lower part of the soybean canopy. If the scout cannot rule out rust, (s)he should contact his/her county Extension agent, consultant, or dealer, to see if (s)he can rule out rust. If (s)he cannot rule out rust, a plant sample should be sent to the Plant Disease and Insect Clinic on NCSU campus. If possible, the sender should note the exact coordinates of where the suspected rust was found.

We 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. This means we consider most of our state’s soybeans to be safe from economic damage from rust this year. 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.