Bud, Flower and Fruit Drop in Citrus and other Fruit Trees

Abstract

Fruit trees usually take many years before they produce a crop. This delay is perhaps longest in pistachio (about 15-20 years) grown for its nuts in some arid areas, and in seedling trees of walnut (10-15 years). In citrus, apple, pear and sweet cherries the delay is approximately 3-5 years but shorter in plums, peaches, apricots and figs. However, the time before first harvest can be shortened by certain cultural and technical measures e.g. girdling and ringing. It is quite obvious that the first requirement for fruiting is the formation of flower buds. But, between the initiation of flower buds and the differentiation to flowers, and from the flowering to fruit setting, many physiological processes must take place before a yield of fruit is achieved. One of the most important of these is the prevention of abscission of generative organs such as flower buds, flowers, small fruit and ripened fruit.