Sensitivity of adzuki bean (Vigna angularis) to preplant-incorporated herbicides.
Six field trials were conducted in Ontario, Canada, during 2003 and 2004 to evaluate tolerance in adzuki bean of the preplant incorporation (PPI) of EPTC (4400 and 8800 g a.i./ha), trifluralin (1155 and 2310 g a.i./ha), dimethenamid (1250 and 2500 g a.i./ha), S-metolachlor [metolachlor] (1600 and 3200 g a.i./ha) and imazethapyr (75 and 150 g a.i./ha). All treatments, including the nontreated control, were maintained weed-free during the growing season. EPTC and dimethenamid caused as much as 39% visual crop injury, reducing plant height, shoot dry weight and yield by up to 34, 63 and 38%, respectively. Maturation was delayed with the application of EPTC and dimethenamid. Trifluralin caused as much as 9% visual crop injury and decreased plant height by up to 11%. Trifluralin had no effect on shoot dry weight, seed moisture content and yield. S-metolachlor caused as much as 19% visual crop injury, decreasing plant height by up to 23% and shoot dry weight by up to 29%. Yield was not affected at the low herbicide rate but was decreased by 19% at the higher herbicide rate. S-Metolachlor had no effect on maturity. Imazethapyr caused up to 6% visual injury but had no adverse effects on plant height, shoot dry weight, seed moisture content and yield except at the high rate, which caused a 15% reduction in plant height. Based on these results, trifluralin and imazethapyr applied PPI have an adequate margin of crop safety for weed management in adzuki bean production in Ontario.