Sensitivity of adzuki, kidney, small red Mexican and white beans to pethoxamid

Pethoxamid has not been evaluated for use in dry bean in Ontario. Seven field experiments were established at three Ontario locations to evaluate the effect of pethoxamid applied preplant incorporated (PPI) and preemergence (PRE) at 1200 and 2400 g ai ha-1 in dry bean. At 2 weeks after emergence (WAE), pethoxamid caused as much as 19, 4, 4 and 6% injury when applied at 1200 g ai ha-1 and 32, 6, 9 and 10% injury when applied at 2400 g ai ha-1 in adzuki, kidney, small red Mexican and white bean, respectively. There was no difference in plant stand of dry beans with pethoxamid PPI and PRE at 1200 or 2400 g ai ha-1. Pethoxamid applied PPI reduced shoot dry weight 15% compared to when applied PRE. Pethoxamid applied at 2400 g ai ha-1 also reduced shoot dry weight 12% compared to when applied at 1200 g ai ha-1. There was no difference in seed yield of adzuki, kidney, small red Mexican and white bean with pethoxamid applied PPI or PRE at 1200 or 2400 g ai ha-1. Based on this study, pethoxamid applied PPI or PRE at the proposed rate of 1200 g ai ha-1 has the potential to cause significant injury in adzuki bean. Pethoxamid applied PPI or PRE at the proposed rate of 1200 g ai ha-1 caused less injury in kidney, small red Mexican and white bean with no effect on seed yield.

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