SPRAY VARIABLE EFFECTS ON ABSCISSION OF ORANGE FRUIT FOR MECHANICAL HARVESTING

Abstract

An experimental abscission chemical, CMN-Pyrazole (CMN-P), was applied to Valencia orange trees toinvestigate 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 efficacywas assessed in terms of fruit detachment force, pre-harvest drop of fruit, and percent fruit removal by the shaker. Atcomparable 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 thanhigher volumes. However, more uniform deposition, lower fruit detachment force, and higher percent fruit removal wereobserved with higher volume sprays. Increasing the ground speed at constant sprayer output improved depositionefficiency, but more uniform spray distribution, better canopy penetration, and higher harvesting efficiencies wereobtained at lower ground speeds.