Broadleaf Weed Control with Halosulfuron Tankmixes in White Bean

Six field trials were conducted over a four-year (2017-2020) period near Exeter and Ridgetown, Ontario to determine the efficacy of halosulfuron tankmixes applied postemergence to control broadleaf weeds in white bean. Halosulfuron caused up to 4% injury in white bean at 2 and 4 weeks after treatment (WAT). Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen caused 2% - 16% injury at 2 WAT and up to 3% injury at 4 WAT in white bean. The addition of halosulfuron to the aforementioned herbicides did not accentuate white bean injury. Reduced weed interference with the herbicides evaluated increased white been yield 50% - 90% compared to the weedy control; there was no difference in seed yield among herbicide treatments evaluated. At 4 WAT, halosulfuron at 25, 37.5 and 50 g ai ha-1 controlled velvetleaf 86%, 93% and 97%; redroot pigweed 83%, 85% and 89%; common ragweed 90%, 93% and 94%; common lambsquarters 27%, 28% and 36%; flower-of-an-hour 66%, 76% and 69%; and wild mustard 100%, 100% and 100%, respectively. Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen controlled velvetleaf 73%, 14%, 52%, 42% and 68%; redroot pigweed 40%, 91%, 85%, 75% and 80%; common ragweed 36%, 81%, 92%, 68% and 84%; common lambsquarters 87%, 39%, 48%, 60% and 76%; flower-of-an-hour 90%, 66%, 63%, 73% and 83%; and wild mustard 97%, 97%, 100%, 99% and 100%, respectively. Halosulfuron tankmixed with bentazon, acifluorfen, fomesafen, bentazon/acifluorfen or bentazon + fomesafen controlled velvetleaf 90%, 51%, 68%, 75% and 90%; redroot pigweed 80%, 99%, 95%, 92% and 91%; common ragweed up to 94%, 97%, 93%, 94% and 95%; common lambsquarters 74%, 62%, 43%, 62% and 66%; flower-of-an-hour 92%, 78%, 74%, 82% and 87%; and wild mustard 100%, 100%, 100%, 100% and 100%, respectively. Weed density and dry biomass followed the same trend. This study concludes that the optimal halosulfuron tankmix is broadleaf weed species specific for weed management in dry bean production.