Sensitivity of Azuki Bean and Control of Multiple Herbicide-Resistant Canada Fleabane With Saflufenacil Herbicide Mixtures

During 2021 and 2022, four experiments were conducted to ascertain the sensitivity of azuki bean to saflufenacil herbicide mixtures, and five experiments were conducted to determine the control of multiple herbicide-resistant (MHR) Canada fleabane with various saflufenacil herbicide mixtures applied preplant (PP) in soybean at various locations in southwestern Ontario, Canada. At 1, 2, 4, and 8 weeks after emergence (WAE), glyphosate + saflufenacil caused 2-5% azuki bean injury. The addition of metribuzin, bromoxynil, halauxifen-methyl, or 2,4-D ester caused 2-7%, 2-4%, 4-9%, and 2-4% azuki bean injury, respectively. Glyphosate + saflufenacil + bromoxynil plus either metribuzin, halauxifen-methyl, or 2,4-D ester caused 3-7%, 5-11%, and 3-6% azuki bean injury, respectively. Saflufenacil mixtures evaluated had no adverse effect on azuki bean stand, biomass m-1, biomass plant-1, height, seed moisture content, or yield. At 4 and 8 weeks after application (WAA), glyphosate + saflufenacil control MHR Canada fleabane 93 and 87%, respectively; there was no improvement in MHR Canada fleabane control with the glyphosate + saflufenacil mixtures evaluated. At 8 WAA, saflufenacil herbicide mixtures evaluated reduced MHR Canada fleabane density 43-95% and biomass 47-96%; differences were not statistically significant. MHR Canada fleabane interference reduced soybean yield 50%; however, reduced MHR Canada fleabane interference with all glyphosate + saflufenacil mixtures evaluated resulted in soybean yield that was similar to the weed-free control. This study concludes that saflufenacil herbicide mixtures evaluated have the potential to be used for the control MHR Canada fleabane in azuki bean.