Successful elimination of vegetation prior to planting cotton (Gossypium hirsutum L.) in reduced tillage production is critical for adequate stand establishment, eliminating early-season weed interference, and maintaining yields. Cutleaf eveningprimrose (Oenothera laciniata Hill) often is prevalent in cotton fields in the spring prior to planting. Field experiments were conducted during 1995 and 1996 in Louisiana and in 1999 in North Carolina to compare cutleaf eveningprimrose control by glyphosate or paraquat applied alone or with cyanazine, cyanazine + thifensulfuron + tribenuron, oxyfluorfen, thifensulfuron + tribenuron, or 2,4-D. Combinations of glyphosate or paraquat with 2,4-D were generally more effective than glyphosate or paraquat applied alone or with other complement herbicides. Applying cyanazine, cyanazine + thifensulfuron + tribenuron, oxyfluorfen, or thifensulfuron + tribenuron with glyphosate was as effective as glyphosate applied with 2,4-D in two, one, four, or three of six experiments, respectively. In contrast, applying cyanazine, cyanazine + thifensulfuron + tribenuron, oxyfluorfen, or thifensulfuron + tribenuron was as effective as paraquat + 2,4-D in one, four, two, or four experiments, respectively. These data suggest that control by herbicide mixtures other than glyphosate or paraquat with 2,4-D are generally less effective. These data also suggest that oxyfluorfen is the most effective herbicide other than 2,4-D to apply with glyphosate to control cutleaf eveningprimrose while thifensulfuron + tribenuron, either alone or with cyanazine, are the most effective herbicides other than 2,4-D to apply with paraquat.
