Daren Mueller, Department of Plant Pathology and Microbiology
During the 2011 season several foliar diseases were present in Iowa, including brown spot, Cercospora leaf blight and frogeye leaf spot. The disease that was noticeably higher in 2011 compared to previous years was frogeye leaf spot, at least in susceptible varieties. The pathogen that causes frogeye leaf spot, Cercospora sojina, has been in the news several times the past couple of years because of reports of resistance to strobilurin fungicides.
Because of these reports, Iowa State researchers collected leaves with frogeye leaf spot from our fungicide trials and sent the leaves to University of Illinois to be tested for sensitivity. All of the isolates collected from the Iowa leaves tested sensitive, which means that they are not resistant to strobilurin fungicides.
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