The Early Season Diagnostic (ESD) tool has been developed by the cotton management support systems team based at the Cotton CRC's Technology Resource Centre. The tool was released on the Australian Cotton CRC web site (cotton.crc.org.au) during the 2003 - 04 season, and has been developed to help growers identify growth problems in their cotton crop. By identifying potential problems sooner, the ESD tool can help growers achieve optimal crop growth, maturity and yield. The system is based on graphically comparing the observed crop development data with an optimum or target line. This target development rate has been generated from data over many years of research conducted by Dr. Greg Constable and colleagues