Devil's-claw and smellmelon are summer annual broadleaf weed problems in the southwest cotton production region. Field studies conducted in 1993 and 1994 evaluated the efficacy of pyrithiobac for postemergence (POST) control of devil's-claw and smellmelon compared with soil-applied fluometuron or prometryn. Pyrithiobac at 0.07 and 0.14 kg ai/ha early POST and 0.14 kg ai/ha mid-POST controlled devil's-claw more than 84% at the late rating. Devil's-claw control with mid-POST applications of pyrithiobac at 0.07 kg ai/ha was reduced when compared with other rates and application timings. Smellmelon control with pyrithiobac ranged from 57 to 84% and, except when applied at 0.07 kg ai/ha early POST, was equivalent to or greater than either fluometuron or prometryn. Crop injury with pyrithiobac treatments 16 d after treatment was 5 to 13%, but 33 d later, was no more than 3%.
