Crop growth rate, lint yield and fiber quality depend to a large extent on climatological conditions from the time the crop is planted until harvested. Knowledge of crop growth rates and phenological stages of development is essential for the proper management of production inputs such as water, fertilizers, insecticides, growth regulators and harvest aids. We developed a system based on a weather station network, a Plant Map Analysis Program (PMAP) and an Integrated Crop Ecosystem Management Model (ICEMM) for monitoring cotton development. The weather station network consists of individual stations located in a farmers' fields. The stations, connected via a telephone modem, are equipped to measure air and soil temperature, solar radiation, rainfall, and wind speed and direction. PMAP is a computer program designed to enter and analyze plant map data. ICEMM is an integrated cotton management system which incorporates a cotton crop and an insect simulation model (TEXCIM), used to perform system analysis of management alternatives. The three software packages are designed to work independently or to complement each other. This integrated crop monitoring system has proved useful for the adaptive management of cotton crops. The system provides information which allows farm managers to modify in-season management practices in response to the changing requirements and potentials of the crop under varying environmental influences.