Iowa State University researchers recently published their annual fungicide trial data for soybeans in 2019, revealing a continued decline in efficiency among the quinone outside inhibitors (QoI) class of fungicides in preventing foliar diseases in soybeans.
Integrated Crop Management News
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Iowa State University researchers, with funding from soybean checkoff through the United Soybean Board and Iowa Soybean Association, have confirmed that over 70 isolates of the pathogen Cercospora sojina (cause of frogeye leafspot in soybeans in Iowa) are resistant to quinone outside inhibitor (QoI) fungicides.
This article summarizes our 2019 corn foliar fungicide trials that were done at six locations in Iowa: ISU Northwest Research and Demonstration Farm (NWRF), Sutherland; Northeast Research and Demonstration Farm (NERF), Nashua; Northern Research and Demonstration Farm (NRF), Kanawha; Southwest Research and Demonstration Farm (SWRF), Lewis; Southeast Research and Demonstration Farm (SERF), Crawfordsville; and the Ag Engineering and Agronomy Farm (AEA) near Boone.
The 2019 growing season was challenging for farmers in many parts of the state, especially because cold and wet soil conditions in April significantly delayed planting. Thistle caterpillar was the most abundant insect statewide, though multiple species of caterpillars, Japanese beetle, soybean aphid, and soybean gall midge were observed in soybean.
The soybean cyst nematode (SCN) has been managed for decades with resistant soybean varieties. Almost all soybean varieties have SCN resistance from a breeding line named PI 88788, and SCN populations have developed high levels of reproduction on the PI 88788 resistance. The results of a field experiment in southeast Iowa in 2019 foreshadow alarming yield loss due to SCN in the future if farmers continue to have only PI 88788 SCN resistance available in soybean varieties.