Postemergence-topical (PT) and postemergence-directed Roundup Ultra applications in Roundup Ready cotton provide new opportunities to control many troublesome annual and perennial weeds without cotton injury. The use of residual herbicides in a Roundup Ready cotton weed control program reduces the potential of interference from early season weed competition, which may result in yield loss. Field experiments were conducted in 1999 at the Texas Agricultural Experiment Station near Lubbock, TX to evaluate rates and timing of residual herbicides in Roundup Ready cotton. Paymaster 2326RR tolerance and weed control were evaluated throughout the growing season. Roundup Ultra (glyphosate) at 0.56 and 0.75 lb ae/A was applied PT at the 4-leaf stage alone and in a tank mixture with Staple (pyrithiobac) at 0.032 and 0.047 lb/A. All treatments received a blanket application of Treflan (trifluralin) applied preplant incorporated at 0.75 lb/A followed by (fb) Caparol (prometryn) applied preemergence at 1.2 lb/A. Above normal rainfall was received in May and June which helped activate soil applied herbicides and promote early season weed emergence. Weed flushes were limited mid-season because of below normal rainfall in July and August.