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2012 APS Annual Meeting Abstract

 

Poster Session: Chemical Control

177-P

Effects of glyphosate application rates on soybean sudden death syndrome.
S. S. Navi (1), L. Jing (1), X. YANG (1)
(1) Iowa State University, Ames, IA, U.S.A.

Outbreaks of soybean sudden death syndrome (SDS) have been reported by farmers following applications of glyphosate at rates greater than label rate. Early study in our lab showed that higher rate applications of glyphosate increased SDS. Rate of glyphosate applications have been increasing since the introduction of Roundup Ready (RR) soybeans. USDA data show that commercial application rate of glyphosate was 0.57 A.I./year (lb/acre) in 1996 and the number was 1.23 in 2006. In recent years use of higher rates of glyphosate for weed management have been practiced by farmers because of the occurrence of glyphosate resistant weeds and availability of cheaper generic glyphosate. We conducted experiments in the greenhouse to investigate the effects of amount of glyphosate on occurrence of SDS in RR soybean. Treatments were established using different glyphosate application rates and application times. Results of this study were consistent with what reported 12 years ago by Sanogo, Yang and Scherm in 2000. Incidence and severity of SDS increased when soybean plants received higher rates of glyphosate, which suggests that over years, the nature of glyphosate effects on the occurrence of SDS in RR soybeans remains unchanged.

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