106 MANUAL OF TROPICAL AND SUBTROPICAL FRUITS 



and root-pruning have been made at the Porto Rico Agricultural 

 Experiment Station. C. F. Kinman reports of them : 



" Girdling, branch pruning, and root pruning are common practices, 

 but they should be used with caution and moderation, as a tree may 

 easily be so severely injured as to prevent its bearing for one or more 

 seasons. Pruning back the ends of the branches to induce blossoming 

 has been practiced with good results at the station. In the operation, 

 from a few inches to a foot of the end of the branch was removed, 

 depending upon the stage of maturity of the wood, leaving a few nodes 

 from which the leaves had not fallen. From these nodes blossom^ 

 developed profusely, no blossoms appearing on untreated branches. 

 To secure best results, the pruning should be done in the late summer 

 or fall, several months before the blossoming time. This method should 

 be employed on branches which are too low or too crowded or on 

 those which would have to be removed later to improve the shape of 

 the tree, as after a branch is pruned it makes little growth for several 

 weeks or months or even for a year or more after the fruit ripens, and 

 by this time it may be well overgrown by surrounding branches. 



"As good results have been obtained from girdling as from other 

 methods. A branch one to three inches in diameter was selected on 

 each of a number of trees and a band of bark removed in September. 

 These branches produced good crops the following spring, even when no 

 fruits at all were borne on the remainder of the tree. Such favorable 

 results, however, were obtained on varieties which are inclined to bear 

 well and where the band of bark removed was wide enough to prevent 

 the new bark from growing over the area too rapidly. Bands one- 

 eighth and even one-quarter of an inch in diameter were overgrown so 

 quickly that no effect was seen on the branch. Bands from one-half 

 to three-quarters of an inch produce the best results, as they do not 

 heal over until after the blossoming season, the callus growing down- 

 ward over the wound at the rate of one inch a year. ... As removing 

 enough bark to induce fruiting is very injurious to the branch, this 

 practice is most profitably employed on undesirable branches which are 

 to be removed later. 



" Root pruning has been recommended, although no definite results 

 have been noted from the experiments with it. It is best accomplished 

 by cutting into the soil with a sharp spade about two feet inside the 

 tips of the branches. In extreme cases the cutting may encircle the 

 tree to a depth of eight or ten inches in heavy soil and even deeper in 

 light soil where the root system is considerably below the surface. 

 Cutting at such intervals as to sever the roots for one-half to two- 

 thirds of the distance around the tree will induce blossoming under 

 normal conditions without seriously checking the growth or thrift of 

 the tree." 



