Characterizing the response of irrigated cotton to hail Damage through canopy reflectance measurements in Arizona

Cotton production in Arizona can experience hail damage in the summer in a time of very active growth. The current method of loss assessment is based on visual inspection that relies on the experience of the insurance adjuster. Through the use of sensor technology, the evaluation system can be greatly improved in the areas of spatial coverage and standardized analysis, with significant time and cost savings. This paper describes research carried out in central Arizona in irrigated cotton during the 2008 growing season. The goal of this project was to characterize through canopy reflectance measurements the crop response to hail damage simulated by manual branch removal. The treatments included a control and 25, 50, 75, and 100% removal of fruiting branches at three growth stages: 0, 14, and 28 days after flowering. The instrumentation included a 16-channel radiometer manufactured by CropScan programmed to scan in a range from 460 to 880 nm. After branch removal treatments, the canopy was scanned up to four times in a time period of 20 days. Preliminary results show that plants responded to the intensity of branch removal with different growth rates. Pending yield data will be added to the final analysis.