Machine-harvest of Sweet Cherries: Effect of Ethephon on Fruit Removal and Quality of the Processed Fruit1

Abstract

Abstract (2-Chloroethyl)phosphonic acid (ethephon) applied as a foliar spray at 250 to 1000 ppm reduced fruit removal force by 30 to 60%, and significantly increased (50 to 300%) the percentage fruit removed by machineharvest in sweet cherry (Prunus avium L.). The response was more pronounced as time between application and harvest increased, with optimum results between 7 and 14 days before harvest. Fruit quality was equal to or better than that of the control, the greatest effect being a reduction in percentage of bruised fruit and fruit with persisting pedicels. The degree of bruising was directly related to the duration of the shaking period. Efficiency of machine-harvest was markedly increased (20 to 30%) by selectively removing the lower branches and heading back long willowy branches around the periphery of the tree. Excessive leaf abscission and gummosis were common at the 1000 ppm rate and occasionally at the lower rates, particularly when trees were under moisture or disease stress.