Evaluation of a Rapid Method to Detect Terbufos Residue Levels in Corn (Zea mays) Seedlings

Abstract

Postemergence applications of nicosulfuron and primisulfuron may injure corn plants depending on the level of terbufos present in the young corn plants from application of terbufos for corn rootworm control. Field studies were conducted in 1992 and 1993 to evaluate the interaction of nicosulfuron and primisulfuron with terbufos and to relate terbufos levels, detected with a rapid detection kit, to injury. Terbufos was applied in-furrow at 0, 186, 375, and 750 g ai/100 m of row. Nicosulfuron was applied at 35 and 70 g ai/ha and primisulfuron at 40 and 80 g ai/ha when the corn was at the four-leaf stage. Prior to herbicide application, both fresh and frozen plant samples from each treatment were subjected to terbufos analysis. The correlation coefficient for terbufos detected in the shoot extract with observed herbicide injury to corn was r = 0.89 in 1992 and r = 0.94 in 1993. Injury ratings showed a greater correlation with terbufos levels than did corn shoot height. Thus, the rapid detection kit provided an efficient method to determine whether an injurious terbufos-herbicide interaction might occur.