Response of Four Dry Bean Market Classes to Pre-Emergence Applications of Pyroxasulfone, Sulfentrazone and Pyroxasulfone plus Sulfentrazone

Abstract

Only one herbicide mode of action (ALS inhibitor) is currently available to Ontario dry bean producers for soil-applied broadleaf weed control. Four field studies were conducted over two years (2014, 2015) to examine the tolerance of four market classes of dry beans to sulfentrazone (210 and 420 g · ai · ha -1 ) and pyroxasulfone (100 and 200 g · ai · ha -1 ) applied alone and in combination. The registration of these two herbicides would provide Ontario dry bean producers with two additional modes of action for broadleaf weed control. Pyroxasulfone caused up to 23%, 6%, 7% and 10% injury in adzuki, kidney, small red Mexican and white bean, respectively; sulfentrazone caused up to 51%, 12%, 15% and 44% injury and the combination caused up to 90%, 23%, 29% and 62% injury, respectively. Kidney and small red Mexican bean density, height, seed moisture content and yield were not affected. Pyroxasulfone (200 g · ai · ha -1 ) + sulfentrazone (420 g · ai · ha -1 ) reduced adzuki and white bean density, shoot dry weight, height and yield. This study concludes that pyroxasulfone (100 g · ai · ha -1 ) + sulfentrazone (210 g · ai · ha -1 ) applied PRE can be safely used to control weeds in Ontario kidney and small red Mexican bean production.