Snap Bean Tolerance to Herbicides in Ontario

Abstract

Snap bean was evaluated for sensitivity to a number of herbicides in field studies conducted during a 2-yr period in Exeter, ON. Preemergence (PRE) applications of metolachlor (1,600 and 3,200 g ai/ha), imazethapyr (75 and 150 g ai/ha), and clomazone plus metobromuron (840 + 1,000 g ai/ha and 1,680 + 2,000 g/ha) were evaluated for visual injury at 7, 14, and 28 d after emergence. Postemergence (POST) applications of imazamox plus fomesafen (25 + 200 g ai/ha and 50 + 400 g/ha), quizalofop-P (72 and 144 g ai/ha), and clethodim (90 and 180 g ai/ha) also were evaluated for visual injury 7, 14, and 28 d after treatment. Plant height and crop yield were assessed for all treatments. Visual injury, stunting, and yield loss were not observed in the metolachlor treatments. Imazethapyr (150 g/ha) caused stunting and reduced snap bean yield in both study years. Clomazone plus metobromuron (1,680 + 2,000 g/ha) injured and stunted snap bean in both years of the study and reduced yield in 2000. Imazamox plus fomesafen (50 + 400 g/ha) injured snap bean in both years but only reduced yield in 2000. Quizalofop-P injured snap bean but did not reduce plant height or yield. Clethodim did not injure, stunt, or reduce yield of snap bean. Metolachlor (PRE), imazamox plus fomesafen (POST), quizalofop-P (POST), and clethodim (POST) have excellent potential as weed management tools in snap bean in Ontario.