Field experiments were conducted at the Texas Agricultural Experiment Station near Lubbock, Texas in 2005 and 2006. The purpose of these experiments were; 1) Evaluate timings using glyphosate in combination with preemergence (PRE) and POST residual herbicides for improved control of Palmer amaranth, 2) Determine the effects of POST application timings on weed competition and cotton yield in Roundup Ready Flex Cotton. Improved Palmer amaranth control was achieved with glyphosate at 0.75 lbs ae/A in conjunction with trifluralin compared to glyphosate alone. Palmer amaranth competition reduced cotton yields when glyphosate applications were delayed, especially when no preplant herbicides were used.