Ethrel as an aid to the mechanical harvesting of sweet cherries

Abstract

Abstract The fruit removal force (FRF) of mature ‘Florence’ cherries (Prunus avium L.) growing in Central Otago exceeded 500 g. Mechanical harvesting of these fruit detached 50-70% of the crop after a 3-sec shake. Ethrel applied either 14 days (500–1000 mg/1) or 8 days (1000 mg/1) before harvest decreased the FRF to less than 300 g and more than 90% of the crop was detached by a 3-sec mechanical shake. High rates of Ethrel (1000 mg/1), however, caused excessive leaf yellowing and gumming around leaf scars. It was necessary to monitor the FRF of each cherry variety before harvest and to apply Ethrel at critical FRF values rather than use set calendar dates or other subjective evaluations of the stage of crop maturity. The quality of brined ‘Twyford’ fruit after Ethrel treatment (400 mg/1) was not different from water treated (control) fruit if the fruit were brined immediately after being mechanically harvested.