Abstract

A total of six field trials were conducted over a three-year period (2009 to 2011) to determine the tolerance of white and adzuki bean to pendimethalin plus reduced doses of imazethapyr applied preplant incorporated (PPI) in Ontario, Canada. There was minimal injury in white and adzuki bean with pendimethalin, imazethapyr and the tankmix of pendimethalin plus imazethapyr applied PPI at Harrow and Ridgetown. In contrast, at Exeter in 2009 and 2010, pendimethalin caused as much as 5 and 8% injury; imazethapyr caused as much as 18 and 5% injury; and the tankmix of pendimethalin plus imazethapyr caused as much as 20 and 14% injury in white and adzuki bean, respectively. Generally, the tank mixture of pendimethalin at 1080 or 2160 g ai ha^-1 and imazethapyr at 37.5 g ai ha^-1 had no adverse effect on height, biomass, seed moisture content and yield of white and adzuki bean. In white bean, the tank mixture of pendimethalin at 1080 or 2160 g ai ha^-1 plus imazethapyr at 75 or 150 g ai ha^-1 resulted in a decrease in height, biomass, and yield of white bean in some environments. In adzuki bean, the tank mixture of pendimethalin at 1080 g ai ha^-1 plus imazethapyr at 37.5, 75 or 150 g ai ha^-1 did not have any adverse effect on height, biomass, seed moisture content or yield. However, when the rate of pendimethalin was increased to 2160 g ai ha^-1 in a tank mixture with imazethapyr at 37.5, 75 or 150 g ai ha^-1, a decrease in adzuki bean height and biomass was observed but there was no effect on seed moisture content or yield. Based on this study, there is an adequate margin of crop safety for pendimethalin at 1080 g ai ha^-1, imazethapyr at 37.5 g ai ha^-1, and the tankmix of pendimethalin plus imazethapyr at 1080 + 37.5 g ai ha^-1 applied PPI in white and adzuki bean.

Key words: Imazethapyr, navy bean, pendimethalin, Phaseolus vulgaris, Vigna angularis.