Response of Soybean Yield Components to 2,4-D

Abstract Soybean plants exposed POST to 2,4-D can have reduced seed yield depending on the dose and time of exposure, but it is unclear how 2,4-D affects specific yield components. Objectives were to quantify soybean injury, characterize changes in seed yield and yield components of soybean plants exposed to 2,4-D, and determine if seed-yield loss can be estimated from visual assessment of crop injury. Ten rates (0, 0.1, 1.1, 11.2, 35, 70, 140, 280, 560, and 2,240 g ae ha−1) of 2,4-D were applied to Becks brand 342 NRR soybean at three soybean growth stages (V2, V5, or R2). The soybeans were planted near Lafayette, IN and Urbana, IL in 2009 and 2010 and near Fowler, IN in 2009. Twenty percent visual soybean injury was caused by 29 to 109 g ha−1 2,4-D at 14 d after treatment (DAT) and 109 to 245 g ha−1 at 28 DAT. Nonlinear regression models were fit to describe the effect of 2,4-D on seed yield and yield components of soybean. Seed yield was reduced by 5% from 87 to 116 g ha−1 and a 10% reduction was cause...