Growth chamber experiments were conducted to determine the effects of soil temperature on the response of corn to imazaquin soil residues. In a silt loam soil, 24/30 C (night/day) or 18/24 C soil temperatures caused greater inhibition of shoot growth than 12/18 C soil temperature. However, in a sandy loam soil, inhibition of corn shoot growth was maximal at 18/24 C, and there was no difference in shoot-growth inhibition between the lowest and highest temperatures. Higher soil temperatures caused greater root-growth inhibition in the sandy loam soil but not in silt loam soil. Soil temperature did not affect 14C-imazaquin uptake from either soil. Higher soil temperatures increased the translocation of imazaquin from root to shoot tissue in both soils. In the sandy loam soil, imazaquin metabolism in root tissue decreased as soil temperature increased, with twice as much parent herbicide recovered from roots of plants grown under the highest compared with the lowest temperature treatments. Soil temperature had no effect on imazaquin metabolism in shoot tissue. Longer-term experiments (22 d) were conducted with the sandy loam soil to determine the effect of changes in air temperature on corn response to imazaquin soil residues. Plants exposed to 24/30 C for 7 or 14 d of the final 14-d growing period showed greater inhibition of shoot growth compared with plants maintained at 12/18 C. Uptake and translocation of 14C-imazaquin to shoots was greater in plants maintained at 24/30 C throughout the final 14-d period than in plants maintained at 12/18 C. Plants grown for 7 d at 24/30 C during the final 14-d period either preceding or following 7 d growth at 12/18 C showed increased translocation of imazaquin to shoots but no difference in imazaquin uptake compared with plants maintained at 12/18 C. Neither air nor soil temperature treatments had any effect on imazaquin concentration in soil water.