Of course, there are other reasons to manually prune orange trees, other than to improve fruit size. If certain insects, like California red scale or cottony cushion scale have been a problem, pesticide spray coverage may be improved by making the canopy less dense through pruning and fruit quality may be improved by making this investment. In general, what this pruning research has reinforced is the concept that growers should know why they are pruning orange trees and that manual pruning is unlikely to increase the number of fruit in the most valuable size ranges.
1Fruit sizes refer to number of fruit that fit into a standard California 37.5 lb. carton.
2 The severe treatment refers to the treatment that included removal of two or more major scaffold branches in spring 2000.