Lima bean cultivar ‘Improved Kingston’ was evaluated for sensitivity to herbicide treatments in a field experiment, conducted from 1999 to 2001 in Ontario. Crop was evaluated for visual injury at 7, 14, and 28 d after emergence following preemergence (PRE) applications of metolachlor (1,600 and 3,200 g ai/ha) and imazethapyr (75 and 150 g ai/ha). Crop visual injury to postemergence (POST) applications of imazamox fomesafen (25 200 g ai/ha and 50 400 g ai/ha) and quizalopfop-P (72 and 144 g ai/ha) was evaluated at 7, 14, and 28 d after treatment. Plant height and crop yield were also assessed. The imazamox fomesafen mixture caused significant visual injury and tended to decrease lima bean height and yield. Despite some initial injury observed in the metolachlor, imazethapyr, and quizalofop-P treatments, yield was not significantly decreased. Because of their margin of crop safety, metolachlor applied PRE at 1,600 g/ha, imazethapyr applied PRE at 75 g/ha, and quizalofop-P applied POST at 72 g/ha have excellent potential as weed management tools in Ontario lima bean production.

Nomenclature: Fomesafen; imazamox; imazethapyr; metolachlor; quizalopfop-P; lima bean, Phaseolus lunatus L.

Additional index words: Herbicide injury, sensitivity.

Abbreviations: DAE, days after emergence; DAT, days after treatment; OM, organic matter; POST, postemergence; PPI, preplant incorporated; PRE, preemergence; UAN, urea ammonium nitrate.