Field experiments were conducted at the Texas Agricultural Experiment Station near Lubbock, TX, in 1994 and 1995 to evaluate devil's-claw control in BXN^TM cotton using postemergence topical (PT) applications of Buctril compared to postemergence directed (PD) Caparol applications with a standard cotton variety, Paymaster HS 26. Treflan was applied preplant incorporated (PPI) at 0.75 lb ai/A and Caparol was applied preemergence (PE) at 1.2 lb ai/A to the entire test areas as part of a typical weed management system for the Texas High Plains. Buctril was applied as a band treatment in single and sequential applications in 1994 and only a single application in 1995 at rates ranging from 0.25 to 1.5 lb ai/A. The Caparol (PD) treatment and the first Buctril treatments (PT) were applied to three to five inch tall weeds in 1994 and one to two inch weeds in 1995. The sequential Buctril treatments (PT) were applied to one inch tall weeds in 1994 only. Middles of cotton rows were cultivated mechanically three times during each growing season.

Excellent crop tolerance was observed for all treatments in both years. In 1994, 1.0 to 1.5 lb ai/A of Buctril controlled devil's-claw 85 - 95% and was significantly more effective than Caparol (PD). Smaller devil's-claw in 1995 were controlled 95 - 100% with Buctril rates as low as 0.38 lb ai/A and no further weeds germinated to require a second application. In 1994, cotton yields generally increased with improved devil's-claw control as Buctril rates increased. Buctril treatments produced higher cotton yields than Treflan alone or Treflan and Caparol (PD). No significant differences were observed in yields between any treatments in 1995.