Through a cooperative agreement with calgene Inc., Rhone Poulenc Ag Company is developing bromoxynil for use on cotton that has been genetically engineered to be tolerant to postemergence applications of bromoxynil, the active ingredient in BUCTRIL^® brand herbicide. Residue and efficacy trials were conducted in 1991 to support the registration of BOCTRIL^® on cotton.

BUCTRIL^® has been applied postemergence to cotton up to 15 lb. ai/A with no injury symptoms. This excellent tolerance to cotton provides the flexibility of concentrating broadcast use rates on a band that provides excellent control of the most troublesome weeds that infest cotton fields. When a broadcast rate of bromoxynil at 0.3751b. ai/A is used at an over-the-row band width that is one fourth the width between cotton rows, the effective rate of bronoxynil within the band would be 1.5 lb. ai/A. Weeds that were susceptible to bromoxynil at this rate include morningglory (Ipomopea sp.), prickly sida (sida spinosa), common cocklebur (Xanthium strumarium), pigweed (Amaranthus sp.), spurge (Euphorbia sp.), hemp sesbania (sesbania exaltata), coffee senna (Cassia occidentalis), and spurred anoda (Anoda cristata). Lower use fates of bromoxynil also provide excellent control of many of these weed species. Sicklepod (Cassia obtusifolia) was shown to be effectively controlled with the high use rates when sicklepod was at the one-leaf stage.