Cotton Heat Stress

Abstract

Heat stress has been a subject of considerable concern among Arizona cotton growers due to a recent string of hot, humid summers. Research studies indicate heat stress develops when mean crop temperature exceeds 82.4F (28C). Serious heat stress develops when mean crop temperatures exceed 86E Several meteorological factors impact crop temperatures in Arizona; however, accurate estimates of crop temperature can be made using a model requiring air and dew point temperature. This model was used to evaluate heat stress conditions in Arizona over the past 10 years. Results from this evaluation show the past three years were difficult years for heat stress. Elevation and humidity levels are major factors impacting heat stress in any given year. Lower elevation areas are more prone to heat stress than high elevation areas such as Safford. Possible management options to minimize the impact of heat stress include early optimal planting dates, variety selection, field location and good water management.