Published online by Cambridge University Press: 12 June 2017
Field studies were conducted in 1994 and 1995 at Dekalb and Urbana, IL, to evaluate preemergence broadleaf weed control and crop tolerance in imidazolinone resistant (IR) and susceptible (non-IR) corn using atrazine, imazethapyr, AC 263,222, CGA-152005, MON 12000 with and without MON 13900 (a safener), and flumetsulam + clopyralid. When sufficient rainfall occurred within 28 d of application to insure herbicide absorption, the IR corn variety was more tolerant than the susceptible variety to imazethapyr, AC 263,222, CGA-152005 at 40 and 80 g/ha, and MON 12000 with and without MON 13900. Overall crop tolerance of IR corn was equal to that of corn treated with atrazine for all herbicide treatments except CGA-152005, which injured IR corn. Control of velvetleaf, common lambsquarters, Pennsylvania smartweed, tall morningglory, and jimsonweed for all herbicide treatments was equal or superior to that of atrazine at 1.7 kg/ha. However, control of common cocklebur was significantly greater with atrazine compared to imazethapyr and the low rate of CGA-152005.