A study was conducted at the University of Arizona Maricopa Agricultural Center, Maricopa, AZ in 1993 to determine the effect of foliar applications of methanol on cotton physiology, growth, yield and whitefly infestation. Six applications of a 30% methanol solution during bloom had no effect on plant height, boll weight, lint yield or earliness of Pima S-7 (Gossypium barbadense L.) or upland DP5415 (Gossypium hirsutum L.) cotton. No effect of methanol on photosynthesis or photorespiration was observed. A significant reduction in sweetpotato whitefly nymph population occurred on DP5415 cotton seven weeks after methanol treatment began. This study provided no evidence that methanol can be used to improve cotton production.