An experimental abscission chemical, CMN-Pyrazole (CMN-P), was applied to 'Valencia' orange trees to investigate the effects of spray variables on fruit 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 detachment force, pre-harvest drop of fruit, and percent fruit removal by the shaker. At comparable volume rates, CMN-P deposition was not significantly different for the Titan tower and AirFlow sprayers; however harvesting efficacy was slightly better with the latter. Lower volume sprays resulted in higher deposition than higher volumes. However more uniform deposition, lower fruit detachment force, and higher percent fruit removal were observed with higher volume sprays. Increasing the ground speed at constant sprayer output improved deposition efficiency, but more uniform spray distribution, better canopy penetration, and higher harvesting efficiencies were obtained at lower ground speeds.
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