Field scale fungicide timing and efficacy trials for corn and soybean diseases in Indiana 

By Kaitlin Waibel

Farmers use financial risk assessment to justify foliar fungicide applications, but yield losses and pesticide overuse can result from producers applying using inefficient timing, choosing ineffective fungicide products, or spraying in the absence of disease. It is generally more cost effective to apply a single application of fungicide than two or three applications. Return on investment for fungicide applications is more likely in years with severe disease pressure or when corn or soybean prices are high. Favorable environments for disease infection change seasonally throughout Indiana with fluctuations in weather and climate. This directly affects fungicide efficacy so it is difficult to establish a baseline timing. Reduced foliar disease severity in field crops does not always increase yield, but foliar disease severity ratings connect yield effects to fungicide application and disease presence.