Effect of fruit wounding and seed removal on abscission of apple fruit between June drop and harvest

Apices only (wounding) or apices plus seeds (seed removal) were removed from fruit of 18‐year‐old apple trees ( Malus domestica Borkh.) of the cultivars ‘Paulared’ and ‘Golden Delicious’ at 2–6 dates between the end of June drop and harvest over a 3‐year period, to determine the effects of these treatments on fruit abscission in the field. Between 33 and 96% of ‘Paulared’ fruit abscised within 2 weeks if deprived of seeds at 4–7 weeks after petal fall. In the same period 0–14% of control and 3–44% of wounded fruit abscised. When the apex of the fruit was removed c. 8–12 weeks after petal fall, almost all fruit abscised whether seeds were removed or not. At the same time abscission of untreated fruit remained low (< 3%). Fruit wounded at 10 or 12 weeks after petal fall and then immediately sprayed with a 1 m M solution of silver thiosulphate abscised less than fruit wounded only. ‘Golden Delicious’ fruit did not abscise prematurely when either wounded or when the seeds were removed early (June‐July). Wounding at the time of fruit maturity (September‐October) increased ethylene evolution significantly only if performed before the climacteric.