The Effects of Mepiquat Chloride Applied to Cotton at Physiological Maturity

Mepiquat chloride is used in cotton to reduce plant height and to promote early maturity. In North Carolina, most mepiquat is applied prior to bloom, at first bloom, or soon thereafter. Recently, there have been claims that mepiquat applied at physiological maturity, or cutout, may further enhance maturity, reduce regrowth potential, and may enhance lint yield. Experiments were conducted during 2007 and 2008 at an on-farm location in Duplin County, North Carolina, and at Tidewater Agricultural Research and Extension Center near Suffolk, Virginia. Treatments consisted of a factorial arrangement of early bloom mepiquat applications of none, 16 oz/A, and 32 oz/A, and late season (cutout) mepiquat applications of none, and 16 oz/A when nodes above white bloom reached a value of 3 to 4. Data suggests that mepiquat applied at early bloom does enhance maturity in environmental conditions that may delay maturity, however mepiquat applied at cutout has little or no effect on maturity, regrowth potential, or lint yield.