Western Ragweed (Ambrosia psilostachya) Control and Bermudagrass Response to Diflufenzopyr Tank-Mix Combinations

Abstract

Research was conducted in 2003 and 2004 to evaluate diflufenzopyr tank mixes for western ragweed control and injury to ‘Tifton 85′ bermudagrass. In 2003 at 94 DAT, picloram at 0.28 and 0.56 kg ae ha−1 with or without diflufenzopyr provided greater than 95% control of western ragweed, whereas triclopyr + dilfufenzopyr, dicamba + diflufenzopyr, triclopyr alone, and diflufenzopyr alone provided < 77% control. In 2004 at 95 DAT, only the highest rate of picloram alone provided 96% control, and the two highest rates of picloram + diflufenzopyr provided at least 95% control. Tifton 85 bermudagrass growth reduction increased with the addition of diflufenzopyr to picloram in 2003, but not in 2004. However, forage dry-matter yield was not reduced by any herbicide treatment compared to the nontreated control. Results of these studies indicate that picloram alone and picloram + diflufenzopyr provide excellent control of western ragweed. The tank mixture of picloram + diflufenzopyr can improve control over picloram alone. However, dicamba + diflufenzopyr, triclopyr + diflufenzopyr, triclopyr alone, and diflufenzopyr alone did not provide adequate control.