Induction of early cropping of guava seedlings in a closely planted orchard using urea as a defoliant

Abstract

A problem with young guava trees is that they carry light and variable crops, and both young and old trees flower and fruit over protracted periods. A 25 % urea spray plus wetting agent applied to 15-month-old guava seedlings of the variety GA9-EX39, produced a three-fold increase in yield over untreated trees at 22 months of age. In addition, the harvesting period was shortened from 15 weeks for control trees to four weeks for sprayed trees. Mean yields for sprayed trees were 34.69 kg, equal to 27.93 t ha-1 at a plant density of 805 trees ha-1; yields for unsprayed trees were 10.85 kg, or 8.73 t ha-1. Such yields exceed those attained in other countries at a similar age. Fruit size was not affected by the urea spray compared with controls, and the second crop 12 months later, also induced with urea sprays, was 40% more than the first. The use of urea as a defoliant spray permits early cropping of young, densely planted orchards and thus faster economic returns. In addition, shortening of the harvest period reduces labour costs and allows better economic control of fruit fly, a major pest of guava.