Cotton Crop Growth and Development Patterns. Cotton: A College of Agriculture Report

Summaries of cotton crop phenology, as a function of heat units (HU, 86/55 °F limits) have been developed across a wide range of production conditions in Arizona. Optimum ranges of HU accumulations since 1 January are used to describe optimal planting dates for full season varieties. Basic events such as the occurrence of pinhead squares, squares susceptible to pink bollworm, and first bloom are described in terms of HU accumulations since planting. Fruit retention guidelines and height: node ratios measures a crop's vegetative /reproductive balance, are developed as a function of HUAP. The use of the number of nodes above the top white bloom to the terminal (NAWB) is developed as a measure of a crops progression towards cut-out. Also, the expected ranges of HU 's accumulated since planting that are required to accomplish crop cut-out are shown for three general maturity types of Upland cotton