Adjuvants to improve pre- and postemergence weed control in soybean, 64-2023

Adjuvants reduce surface tension that may allow soil-applied herbicides to penetrate dense crop residue. This research sought to evaluate the effectiveness of several herbicide-adjuvant combinations for control of Amaranthus spp., Sida spinosa, and Echinochloa crus-galli in soybean, and the effectiveness of two surfactants for improving preemergence herbicide efficacy in a cover crop system. Generally, the herbicide/adjuvant combinations evaluated had no effect on visual weed control. However, weed control differences due to herbicide were observed. Additionally, use of an NIS adjuvant with herbicides evaluated generally improved soil deposition; however, soil deposition of herbicides were not improved by addition of an OS adjuvant. Droplet size and solution deposition at the soil surface were correlated.