Protection of Corn (Zea mays) and Sorghum (Sorghum bicolor) from Imazethapyr Toxicity with Antidotes

Abstract

Antidotes were evaluated under greenhouse conditions for their ability to prevent injury to corn and sorghum from imazethapyr. Corn was more tolerant to imazethapyr and more effectively protected from imazethapyr toxicity than sorghum. Naphthalic anhydride (NA)3, CGA 92194, or flurazole treatment of corn seed reduced plant injury from preemergence applications of imazethapyr. Corn injury from postemergence applications of imazethapyr was decreased by seed treatment with NA or CGA 92194. Sorghum injury from preemergence applications of imazethapyr was not reduced by seed treatment with the antidotes. NA treatment of sorghum seed was the most effective antidote treatment for decreasing injury from postemergence applications of imazethapyr but the level of sorghum protection was much less than that achieved with corn. Corn seedlings grown from NA-treated and untreated seed absorbed equal amounts of14C into the roots from nutrient solution containing14C-imazethapyr. The NA-treated corn plants translocated less of the absorbed14C to the shoots than the untreated plants. NA treatment of corn seeds increased the rate of imazethapyr conversion to soluble metabolites 2-and 10-fold in the corn seedling roots and shoots, respectively. The increased rate of imazethapyr metabolism in corn following NA seed treatment may be responsible for the protection from imazethapyr toxicity.