Tolerance of cranberry beans (Phaseolus vulgaris) to soil applications of s-metolachlor and imazethapyr

Abstract

There is little information on the tolerance of cranberry beans to preplant incorporated (PPI) and preemergence (PRE) applications of s-metolachlor and imazethapyr, either alone or in tank mix combination, for selective weed control in cranberry beans in Ontario. Tolerance of two cranberry bean cultivars, Hooter and SVM Taylor, to PPI and PRE applications of s-metolachlor, imazethapyr and their tank mix combination at the label rate (1x) and twice the label rate (2x) were studied at two Ontario locations (Exeter and Ridgetown) in 2001 and 2002. There were no differences between the two cultivars in their responses to the herbicide treatments. PPI and PRE applications of s-metolachlor alone at the 1x and 2x rate had no effect on visual crop injury and no negative effect on plant height, dry weight and yield compared to the control. The PPI and PRE applications of imazethapyr at the 1x rate did not result in significant visual crop injury, and had no negative effect on bean height and dry weight, but at the 2x rate there was significant visual crop injury, a decrease in height with the PPI application and decreased dry weight with PPI and PRE applications. No negative effect on cranberry bean yield was observed with the application of imazethapyr at either the 1x or 2x rates. The PPI and PRE applications of the tank mix of s-metolachlor plus imazethapyr at the 1x rate did not result in significant visual crop injury or decreases in bean plant height or dry weight. At the 2x rate, there was significant visual crop injury, a decrease in bean plant height with PPI and PRE applications and decreased dry weight with the PPI application. The tank mix of s-metolachlor plus imazethapyr at the 1x rate had no effect on yield, but the PPI application at the 2x rate caused a decrease in yield at 1 of the 4 site-years.