EPTC Reduces Alfalfa (Medicago sativa) Tolerance to Bromoxynil

Abstract

EPTC applied at the time of ‘Saranac AR’ alfalfa establishment resulted in higher levels of crop injury from the octanoic acid ester of bromoxynil applied postemergence compared to alfalfa in areas not treated with EPTC. EPTC applied at 1.7 or 3.4 kg ai ha-1did not injure alfalfa. At Rock Springs, PA, 0.54 kg ai ha-1bromoxynil caused 28, 43, and 55% foliar injury in areas treated with 0, 1.7, and 3.4 kg ai ha-1EPTC, respectively. A similar interaction was observed at Landisville, PA, although the level of injury due to bromoxynil was less severe. EPTC also predisposed ‘WL 316’ alfalfa to bromoxynil injury in greenhouse experiments.