INCREASING PERSIMMON YIELDS WITH GIBBERELLIC ACID

Most of the persimmon (Diospyros kaki) area in Israel is planted with cv. 'Triumph' grafted on Diospyros virginiana rootstock. Cv. 'Triumph' has several advantages, but its yields during its first productive years are low. No problems of differentiation, pollination, or fertilization exist in Israel. The trees flower abundantly, and there is parthenocarpic fruit set. The low yields in the early years seem to be due to fruit abscission.

In order to increase fruit set and reduce fruit abscission, trees were treated with various growth regulators. A spray of GA₃ (gibberellic acid) at a concentration of 15–30 ppm at full bloom significantly increased yields (by 50–400%). In young trees (4–5 years old), a narrow (2–3 mm) girdling at the time of sprouting, together with GA₃, gave best results.