140 Trees, Stars, and Birds 



partly through from beneath, 8 or 10 inches from the 

 trunk. 



It is better to prune a little every year than to prune 

 severely at one time. The main limbs and the branches 

 attached directly to them should be left, and pruning 

 limited to the third and fourth divisions in the branching. 

 If shade trees have branches so low as to interfere with 

 people or vehicles passing under them or with illumina- 

 tion by street lights, it is usually best to trim off the 

 smaller branches rather than larger ones. When a tree 

 is growing the layers of lower branches should be re- 

 moved, not all at one time, but at intervals of a year 

 or more, until the trunk has become clear to the desired 

 height. 



Pruning should be done when there are no leaves on 

 the tree. The leaves are the tree's food factory, and if 

 the pruning is done while the tree is in foliage, both the 

 factory and the reserve food supply in the leaves will be 

 lost. However, the wounds heal more quickly if the 

 pruning is done after growth begins in the spring than 

 when the pruning is done earlier, while the tree is dor- 

 mant. In case it" becomes necessary to cut a large root 

 of a tree, some of the crown on the same side should be 

 cut away also, for otherwise the remaining roots will be 

 unable to supply enough water for the leaves. 



Spraying. The spraying of trees receives much more 

 attention now than formerly. It is of great importance 

 for both fruit and shade trees. The agricultural experi- 

 ment stations issue bulletins that give formulae for 

 preparing the spraying mixtures and methods of apply- 

 ing them. In many cases it is necessary to spray more 



