Weed control efficacy and dry bean response to preemergence herbicide incorporation timing

Abstract

AbstractField experiments were conducted in 2021 and 2022 to evaluate the effect of irrigation timing on S‐ethyl‐N,N‐dipropylthiocarbamate (EPTC), flumioxazin, pyroxasulfone, and flumioxazin + pyroxasulfone weed control efficacy and safety in dry bean (Phaseolus vulgaris L.). Treatments consisted of EPTC (3430 g ai ha−1), flumioxazin (53.6 g ai ha−1), pyroxasulfone (119 g ai ha−1), and flumioxazin + pyroxasulfone (70.4 + 89.3 g ai ha−1) incorporated with overhead irrigation at 1, 4, and 8 days after herbicide treatment (DAT). A nontreated and hand‐weeded check were included for comparison. Delaying irrigation until 8 DAT resulted in 11% and 19% injury in the pyroxasulfone and flumioxazin + pyroxasulfone treatments, respectively, but the crop recovered within 5 weeks after treatment. Delaying irrigation until 8 DAT increased total weed dry weight by 52%. Generally, flumioxazin + pyroxasulfone provided better weed control compared to flumioxazin or pyroxasulfone applied alone. Irrigation timing did not influence dry bean yield. Seed yield was 160 kg ha−1 in the nontreated check and 2521 kg ha−1 in the hand‐weeded check. Seed yield in the flumioxazin + pyroxasulfone treatment (2425 kg ha−1) was similar to the hand‐weeded check. Flumioxazin + pyroxasulfone provided very good weed control with acceptable crop safety. While irrigation timing may play a role in flumioxazin or pyroxasulfone injury, other soil and environmental factors may influence dry bean response to these herbicides.