The duration of imazaquin soil activity on corn, grain sorghum, rice, and cotton was studied from 1988 to 1990. Imazaquin applied at 0.035, 0.07, 0.14 (1× rate), and 0.28 kg ai ha−1 was incorporated into the soil, and rotational crops were planted at various times after application. Initial crop visual injury was directly related to imazaquin application rate. Cotton was most susceptible, followed by corn, grain sorghum, and rice. The carryover of imazaquin from soybeans to cotton, grain sorghum, and wheat was studied in separate experiments in Arkansas in 1987 to 1989. Wheat planted in the fall following soybean harvest was not affected by imazaquin residues. Grain sorghum planted the following spring was injured (16–35%), but there was no yield reduction. Cotton recovered from early injury (< 35%) in one year and did not recover from severe injury (> 50%) in the other, resulting in yield reduction.
