Corn cultivars differed in their response to imazaquin applied from 35 to 280 g ai/ha, as measured by shoot length. No cultivar was tolerant to all imazaquin application rates. There was less corn injury from imazaquin in studies conducted during the second and third years of research than in the first year. Preplant-incorporated applications caused significantly more injury than preemergence applications in two out of three studies. Lack of rainfall in 1985 and 1987 may have limited movement of imazaquin in the soil profile, which resulted in preemergence applications of imazaquin, causing very little corn injury. In all years of research, 35 g/ha of imazaquin incorporated in the top 6 cm of the soil profile resulted in 17 to 33% reduction in corn height 28 days after planting, when averaged across all the corn cultivars. Significant yield reductions (LSD = 0.10) of 45, 19, and 18% occurred in 1987 from preplantincorporated applications of 140, 70, and 35 g/ha, respectively, which had reduced corn height 46, 23, and 19%, respectively, when measured 28 days after planting.
