Field studies were conducted in 2004, 2005, and 2006 to evaluate weed control with pendimethalin preemergence applied in conservation tillage cotton. Pendimethalin was applied at eight weeks before planting (8 WBP) as an aqueous solution (sprayed), or as either an aqueous solution or impregnated on fertilizer at four weeks before planting (4 WBP) or at planting (AP). Texas millet (Urochloa texana (Buckl.) R. Webster) and Florida pusley (Richardia scabra L.) control were similar when pendimethalin was impregnated on fertilizer as compared to pendimethalin spray applied in 140 L/ha of water at 4 WBP or AP. Control of Florida pusley (30 to 69%) and Texas millet (47 to 78%) were variable when single application of pendimethalin was applied 4WBP or 8WBP, regardless of method of application. Pendimethalin impregnated on 280 or 560 kg/ha fertilizer either 4 WBP or AP, did not negatively affect weed control. Maximum and similar Texas millet(71 to 95%) and Florida pusley (80 to 83%) control four weeks after planting occurred with a split application of pendimethalin at 0.84 kg/ha as a aqueous spray in 140 L/ha at 4 WBP followed by the same treatment AP, or when pendimethalin at 0.84 kg/ha was impregnated on 280 or 560 kg/ha fertilizer 4 WBP followed by pendimethalin at 0.84 kg/ha spray applied in 140 L/ha AP.
