Reduction of Imazaquin Injury to Corn (Zea mays) and Sorghum (Sorghum bicolor) by Antidotes

Antidotes were evaluated for their ability to prevent corn and sorghum injury caused by imazaquin. Plant injury was reduced in both preemergence and early postemergence imazaquin applications. Naphthalic anhydride (NA) seed treatment was the most consistent compound in reducing the imazaquin injury. Seed treatment with CGA 92194 or flurazole also gave injury protection to corn and sorghum, while soil treatment with dichlormid provided the least protection from imazaquin injury. Treatment with the antidotes did not affect the acetolactate synthase (ALS) (EC4.1.3.18) activity in corn or sorghum tissues. Imazaquin treatments decreased extractable ALS activity but this decrease was eliminated, partially or totally, by the most effective antidotes. Antidote treatments had little effect on absorption and distribution of14C in plants growing in soil treated with14C-imazaquin. Antidote treatments increased the metabolism of14C-imazaquin to both soluble and unextractable14C after 24 h of exposure. The increased rate of imazaquin conversion to less toxic metabolites when antidotes were used resulted in a reduction in imazaquin injury to corn and sorghum.