Whats happening in Iowa soybean fields?
Last week many ISU Extension field agronomists across the state reported seeing foliar diseases on corn and soybean plants. Soybean brown spot and frogeye leaf spot were reported with some reports of high levels of prevalence. “My own field scouting also indicates the level of these diseases is higher than in a normal season, which is not surprising due to the cooler and wetter-than-normal weather,” says Yang. * When should you spray? The R3 growth stage of soybeans is the time to pull the trigger if foliar disease risk is high in your soybean fields. Application at R1 or earlier did not pay off in the past several years of ISU studies. Application at R3 consistently produces the highest yields across Iowa and surrounding states. R3 is the growth stage when soybean starts to set pods. * How to assess the risk of disease? Even when the season is cool across Iowa, the disease risk is not evenly spread. This year the summer temperatures are cooler than those during the past four seasons.
