Sixteen cultivars of cotton were inoculated with a mixture of three Agrobacterium biovar 1 strains and grown with complete nutrition in controlled environment chambers at constant temperatures of 24, 27, 30, 33, and 36 °C. After six weeks, leaf, stem, shoot, root, and whole-plant weights and Agrobacterium concentrations in roots were determined. Bacterial concentrations per gram of whole plant tissue increased progressively as temperatures were increased, with a major increase occurring between 30 and 33 °C. Concentrations of Agrobacterium at 33 and 36 °C were two- to ten-fold higher than at 27 and 30 °C in each of the sixteen cultivars. Maximum cotton growth occurred at 30 °C, and a major decrease in growth occurred between 33 and 36 °C. Certain cultivars developed bronze wilt symptoms at 36 °C and symptom severity was correlated with reduction of growth. The coefficient of variability for root or shoot weight among cultivars was much greater at 36 °C than at 33 °C or lower temperatures. These observations indicated that root, shoot, or plant weight of Agrobacterium-inoculated plants after six weeks of growth at 36 °C can be used as a quantitative measure of bronze wilt susceptibility in cultivars. This screen was applied to 120 cultivars and breeding lines, and the results are presented.