New trait technology incorporating 2,4-dichlorophenoxyacetic acid (2,4-D) resistance in soybean provides an alternative method to control weeds. However, the effect of postemergence treatments of 2,4-D on aryloxyalkanoate dioxygenase-12 (AAD-12) soybean on injury and yield components has not been reported. Our objectives were to characterize the effect of 2,4-D (dimethylamine salt) rates (0, 1,120, and 2,240 g ae ha⁻¹) and soybean growth stage (V5, R2, or V5 followed by R2) on AAD-12 soybean injury and yield components. Less than 3% soybean injury was observed when 2,240 g ha⁻¹ of 2,4-D was applied to R2 soybean, and less than 1% soybean injury was caused by 1,120 g ha⁻¹ of 2,4-D. Seed yield, seed mass, pod number, seed number, seed per pod, reproductive node number, pods per reproductive node, node number, and percent reproductive nodes were not affected by 2,4-D treatments when applied at the V5, R2, or the V5 followed by R2 soybean growth stage. This research demonstrates that soybean transformed with AAD-12 can tolerate foliar applications of 2,4-D at rates up to 2,240 g ha⁻¹ with no effect on soybean grain yield components.

Nomenclature: 2,4-D (dimethylamine salt); Glycine max (L.) Merr., soybean.