Field studies on a sandy loam soil determined the influence of application method and rate and subsequent tillage on corn response to imazaquin and imazethapyr residues remaining in the soil. Imazaquin was applied preplant incorporated (PPI) and preemergence (PRE) at 70, 140, and 280 g ai/ha and postemergence (POST) at 70 and 140 g/ha. Imazethapyr was applied PPI and PRE at 70, 105, and 140 g ai/ha and POST at 70 and 105 g/ha. Subsequent tillage included fall moldboard plowing followed by spring field cultivation, fall chisel plowing followed by spring field cultivation, and no tillage. Herbicide dissipation was determined by analyzing soil cores taken in the spring at the time of corn planting and by measuring corn height and grain yield. Imidazolinone residues were detected in only 1 of 2 yr. Imazaquin was detected more frequently than imazethapyr. Imazaquin concentrations in the upper 10 cm of soil 11 mo after a PPI application of 280 g/ha were 5, 6, and 7 ng/g of soil in moldboard plow, chisel, and no-tillage systems, respectively. Imazaquin (5 ng/g) was also detected in the 10–18-cm soil depth in the moldboard plow system. Corn height and grain yield were not reduced from imazaquin or imazethapyr, regardless of application method or rate in any tillage system.