Tolerance of adzuki bean to pre-emergence herbicides

Limited pre-emergence herbicide options are available for weed management in adzuki bean in Ontario. Eight field trials were conducted in Ontario over a 3-yr period (2012, 2013, 2014) to evaluate the tolerance of adzuki bean to pyroxasulfone (150 and 300 g a.i. ha 1), flumioxazin (71 and 142 g a.i. ha-1), sulfentrazone (420 and 840 g a.i. ha-1), fomesafen (240 and 480 g a.i. ha-1), imazethapyr (75 and 150 g a.i. ha-1), and cloransulam-methyl (35 and 70 g a.i. ha-1) applied pre-emergence. Pyroxasulfone, flumioxazin and sulfentrazone applied pre-emergence at the proposed 1 and 2 rates caused 25 96% injury and reduced plant stand up to 78%, shoot dry weight up to 95%, plant height up to 67% and seed yield up to 76% in adzuki bean. Cloransulam-methyl resulted in 1 to 9% injury with no adverse effect on plant stand, shoot dry weight, plant height, seed moisture content and seed yield of adzuki bean. Fomesafen and imazethapyr resulted in 1 3% injury with no adverse effect on plant stand, shoot dry weight, plant height, seed moisture content and seed yield of adzuki bean. Based on these results, pyroxasulfone, flumioxazin and sulfentrazone do not have an adequate margin of crop safety for weed management in adzuki bean. Cloransulam-methyl has potential for use in adzuki bean, especially at the lower rate. Imazethapyr and fomesafen at the rates evaluated can be used safely in adzuki bean production under Ontario environmental conditions.