Soybean stand and yield impact from a fungicide seed treatment in North Carolina soybean production

Abstract

North Carolina soybean [Glycine max (L.) Merr.] producers have shifted to earlier planting dates as a mechanism to increase soybean yields. As growers have shifted to earlier planting dates, soybean fungicide seed treatment use has become more common. In 2020 and 2021, on-farm research investigated the value of a fungicide seed treatment across the state. Experiments were conducted across 18 diverse production environments in North Carolina during that time. Treatments included fungicide seed treatment (fludioxonil: 2.32%, mefenoxam: 13.9%, and sedaxane: 2.32%, i.e., Vibrance Trio, a commonly used multi-mode of action fungicide across the state and country) compared to untreated seed. Data collected included soybean stand and soybean yield. The use of a fungicide seed treatment variably affected stand, but when combined over environments, fungicide seed treated plots averaged 110,757 plants/acre as opposed to untreated plots averaging 101,570 plants/acre with significant stand protection in seven of 18 environments. When averaged across environments, fungicide seed treatment protected yield by 1.3 bu/acre which, depending on input practices and soybean selling price, would border providing a return on investment. As planting date was delayed past mid-April, yield decreased for both fungicide treated and untreated plots. Results from this trial indicate that fungicide seed treatments can provide protection of soybean yield and stand in North Carolina although protection provided may not provide a return on investment with current input prices.