Impact on Plant Development and Yield of Various Application Timings of Fomesafen and Lactofen.

Glyphosate resistance in multiple weed species is an increasingly prevalent issue that continues to spread in soybean fields across the U.S. In response to more frequent glyphosate failures, tank mix partners are commonly being used to kill emerged glyphosate-resistant weeds in soybeans. The most common of these tank mix partners are PPO-inhibiting herbicides. These applications are often made as rescue treatments during the reproductive phases in order to control weed escapes and herbicide failures. However, applying PPO-inhibiting herbicides during reproductive phases could potentially have negative impacts on yield due to loss of flowers and early developing pods. The purpose of this study is to evaluate the impact on plant development and yield of various application timings of two commercially available PPO-inhibiting herbicides. The two herbicides being tested are fomesafen and lactofen, and the application timings range from V3-R3. Evaluations include visual response ratings, impact on soybean yield components including node and pod counts and seed weight, in addition to evaluating final yield.