PRUNING 21 



birches, spruces, and sugar maples. If the leader is killed it is often 

 possible to train the best lateral available as a substitute. This may 

 be done by binding the lateral to a pole and tying with raffia. 



If the tree is weakened or is dying, severe pruning will often aid in 

 offsetting the trouble and may help the tree to recover its vigour. 

 Many trees and shrubs, as poplars, soft maples, the tree of heaven, 

 box elders, hydrangeas, and sumacs will stand very heavy pruning and 

 recover rapidly. Oaks, elms, and flowering dogwoods should be pruned 

 only as corrective measures and not to check growth. 



During the progress of construction work in the neighbourhood of 

 fine trees or shrubs some protection should be afforded, either by the 

 erection of a stout fence or a stout wooden framework. 



Root Pruning. Root pruning serves to check the growth of a tree 

 and to encourage lateral or secondary growth of the roots. When 

 a plant has a slow or a weak-growing top grafted upon a vigor- 

 ous root stock, root pruning is often used advantageously to stop 

 too great a growth of the stock. Root pruning should be done before 

 the weather becomes too cold in the fall. If this pruning is delayed till 

 very late no start in healing the cuts will be made before spring, and 

 meanwhile decay will set in. The process of root pruning to assist in 

 the successful transplanting of trees is effected by excavating a narrow 

 trench around the tree encircling a ball of earth (Usually six to eight 

 feet in diameter) (See Plate VI-C-i) which can be handled with a tree 

 machine. In this way one-half to two-thirds of the large roots are 

 severed. The trench is filled with loam, and during the remainder of 

 the growing season a mass of new fibrous roots form, which readily 

 come to the aid of the tree when transplanted to its new location 

 (See Planting and Transplanting, Page 42). 



All trees should be top pruned when transplanted. This is done to 

 offset the loss of root system by removing a portion of the top. A 

 general rule is to remove four-fifths of the current year's growth and 

 one-eighth of the older branches. Do not cut back main laterals or 

 leaders so as to leave large stubs, for with such pruning the stubs will 

 rot and spoil the tree. 



Trees with ample fibrous roots, such as maples and elms, are easier 

 to move successfully than trees with few roots, or with tap roots, such 

 as magnolias, tuHps, gums, and nut trees. It is therefore necessary to 

 prune the tops more heavily on transplanted stock with sparse root 



