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Poster: Biology & Disease Mgmt: Integrated Pest Mgmt


Decision models for fungicide applications for frogeye leaf spot in soybean
H. Kelly (1) (1) University of TN, U.S.A.

Frogeye leaf spot (FLS), caused by Cercospora sojina, is a common foliar pathogen of soybean in the United States and other soybean production areas in the world. While foliar fungicides can reduced disease severity and yield loss caused by FLS on susceptible cultivars, the appropriate application timing is essential for optimal fungicide efficacy and yield protection. To better manage FLS epidemics in Tennessee, fungicide application decision models were developed and evaluated across locations in 3 different counties in 2013 and 2014. Application models were developed based on growth stage of soybean and rain/irrigation events or temperature and relative humidity parameters. The number and timing of fungicide applications varied by location, year, and application model. All applications reduced disease severity, but only applications under moderate to severe disease pressure were necessary to protect yield. Results indicate models for fungicide application timing for FLS management need to incorporate additional disease parameters to more accurately trigger fungicide applications based on environmental factors and soybean growth stage.