Pest Alert: Soybean Rust Update

— Written By NC State Extension

Date: October 2, 2013

From: Jim Dunphy, Extension Soybean Specialist, and Steve Koenning, Extension Plant Pathologist

Soybean rust was identified on a soybean sample submitted by Alan Baucaum from Union County. Severity was low with pustules on 4 leaves out of 50. We did not find rust this week on samples from Columbus, Johnston, or Wayne counties so far. Combined with the confirmed finds in Scotland, Cleveland, Cumberland and Rowan counties, North Carolina, and Suffolk and Isle of Wight counties, Virginia, essentially all the state’s soybeans are within 100 miles of known rust.

We would consider that rust spores are probably in any soybean field in the state, but we wouldn’t expect the disease to develop very rapidly in the drier parts of the state. We would recommend spraying a fungicide on any soybeans in the state which have started blooming, which do not yet have full sized seeds in the top four nodes of the plant, and which appear to have a yield potential of 20 bushels per acre or more. Low night temperatures we are experiencing currently are not conducive to development of soybean rust. Late planted soybeans are still at risk though it seems likely that much of the states’ soybean crop will not be affected adversely by rust this year.

Rust has now been confirmed this year on soybeans in 139 counties or parishes in eleven states (Louisiana, Florida, Alabama, Mississippi, Georgia, North Carolina, South Carolina, Arkansas, Tennessee, Virginia and Kentucky).

Some sources for more detailed information on Asiatic soybean rust are listed below:

USDA soybean rust web site: http://www.sbrusa.net/

North Carolina Agricultural Chemical Manual: https://content.ces.ncsu.edu/north-carolina-agricultural-chemicals-manual

Updated on Mar 17, 2014
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