Adzuki bean (Vigna angularis) responses to post-emergence herbicides

There are few herbicide options available for weed management in adzuki beans in Ontario. Six field trials were conducted in Ontario over a 2-year period (2003 and 2004) to evaluate the tolerance of adzuki bean to the post-emergence application of bentazon, fomesafen, sethoxydim, quizalofop-p-ethyl, imazamox plus fomesafen and imazamox plus bentazon. All treatments including the non-treated control were maintained weed free for the complete growing season. The application of bentazon and imazamox plus bentazon caused visual injury and reduced plant height up to 43%, reduced shoot dry weight up to 65%, delayed maturity and reduced adzuki bean yield as much as 56%. Fomesafen, sethoxydim, quizalofop-p-ethyl, and imazamox plus fomesafen caused visual injury but this was transient and there was no adverse affect on plant height, shoot dry weight, seed moisture content and yield of adzuki bean. Fomesafen and imazamox plus fomesafen reduced shoot dry weight by 16% and delayed maturity at the high dose. Based on these results, the application of fomesafen, sethoxydim, quizalofop-p-ethyl and imazamox plus fomesafen has an adequate margin of crop safety for weed management in adzuki beans in Ontario, but bentazon and imazamox plus bentazon do not.