Heat Stress and Low Desert Cotton - Results of 2018 Experimentation

Heat stress is known to significantly reduce cotton yields in the low desert, with this reduction thought primarily due to stress related ethylene production. Growers have commented that losses can reach up to two bales per acre in certain years. Large scale, replicated strip trials were designed and conducted in three fields of DPL1549 B2XF cotton in 2018 which evaluated BioHold and Urea Mate for their ability to offset heat-stress, with the former product targeting stress and the latter providing additional nutrition. Two sets of timings were evaluated, each with three applications about 10-14 days apart: prior to expected heat stress, and later in season when heat stress was present. Heat stress arrived much later in 2018 than in previous years, with first night of heat stress (Level 1) not noted until July 7. Early applications of materials beginning in late May near first flower had no effect on yields as stress was lacking. The later set of applications started at various points during the year, resulting in a range of final application dates over the summer and with varying durations of stress periods. Applications applied during stress did result in yield increases, with these increases being from 0.35-0.55 bales (480 lbs.)/acre. The field that had its last application applied prior to heat stress being noted was not noted to have increased yields.