PKUNING. 



25 



approximately so; fastigiate and round crown of the same species should 

 not be intermixed. 



Forked stems are to be avoided in all trees and especially in elms, which 

 are likely to split in large forks (PL III). This is remedied by pruning 

 at the time the tree is planted and within a few years thereafter. A mush- 

 room shape which water oaks especially (PI. IV, B) tend to assume when 

 planted as large-topped poles is equally as undesirable. This is altered 

 by cutting back the upper horizontal branches so as to force the formation 

 of a leader. In such a case the leader should either spring from the 

 stem or very close to it and should not be permitted to develop from a 

 horizontal branch at a considerable distance from the stem. Feathered 

 stems which elms and other trees also occasionally form are not de- 



Pia. 5. 



Pig. 5. — Since there is danger of large limbs splitting and tearing the bark loose from 

 the tree, it is preferable to cut them twice. AB shows the position of the first cut, an 

 undercut being first made with a hatchet, the branch then sawn off from above. The 

 stub is then sawn of£ smoothly at CD as close as possible to the line of sap flow. 



sirable. They are remedied by removing quite a number of the feather 

 branchlets with light topping at the same time in order to force a 

 stronger growth in the remaining lateral branches. The development of 

 more than one leader in trees which form a pyramidal crown should be 

 checked by cutting out all except the most vigorous and best-shaped leader. 

 On the other hand, in elms, lindens, ashes and maples, it is desirable to 

 secure a great number of well spaced ascending branches and no single 

 leader. 



The tendency to form irregularities in shape is checked by clipping 

 small branchlets or twigs while the aberration is yet insignificant. By 

 clipping those whose development is not desired, the growth of the others 



