In order to maximize the efficacy of cotton defoliants, site-specific applications were made based on vegetative growth of cotton. Multispectral aerial imagery with 0.5m resolution was utilized to distinguish varying levels of vegetative growth. Normalized difference vegetative index (NDVI) was calculated for the entire field and cotton defoliant rates were assigned based on these data. Higher NDVI levels received higher rates of ethephon and defoliant, while lower NDVI levels received lower rates. The results indicated that the site-specific application was as effective as the commonly used method of a single rate broadcast application. Furthermore, the site-specific method was able to reduce input in areas that required lower rates of chemical while maximizing efficacy in areas that required higher rates of ethephon and defoliant.