Spray variable effects on abscission of orange fruit for mechanical harvesting

An experimental abscission chemical, CMN-Pyrazole (CMN-P), was applied to ' Valencia' orange trees to investigate the effects of spray variables on fru it detachment force and mechanical harvesting efficiency of a trunk shaker: Spray variables included sprayer type, spray volume, ground speed, and CMN -P application rate. Harvesting efficacy was assessed in terms of fruit det achment force, pre-harvest drop of fruit, and percent fruit removal by the shaker At comparable volume rates, CMN-P deposition was not significantly d ifferent for the Titan tower and Airflow sprayers; however, harvesting effi cacy was slightly better with the latter. Lower volume sprays resulted in h igher deposition than higher volumes. However, more uniform deposition, low er fruit detachment force, and higher percent fruit removal were observed w ith higher volume sprays. Increasing the ground speed at constant sprayer o utput improved deposition efficiency, but more uniform spray distribution, better canopy penetration and higher harvesting efficiencies were obtained at lower ground speeds.