Postemergence weed control is a challenge for cotton producers. Cotton has been developed that is tolerant to the broad spectrum herbicide Roundup Ultra®. The advantages of Roundup ReadyTM cotton include control of a wide range of weed species and favorable environmental profile. The growth stage of cotton determines the application window. Over-the-top treatment is permitted before the fifth true-leaf stage and after 20% open. From the fifth true-leaf stage through 20% open, Roundup Ultra® can be applied only with directed application equipment. Little research has been conducted to determine the extent of injury to the plant from over-the-top and post-directed applications during this interval. Thus, our objective was to investigate the effect of application of Roundup Ultra® during this period.