STREET TREES. 



PRUNING. 



Under normal conditions a tree needs little or no pruning 

 luir, at least until it gets ragged from age, is best left to de- 

 vi- lop its natural form. Shade trees, however, frequently re- 

 quire pruning to adapt them to their surroundings and to 

 maintain a healthy growth. A tree does not develop at ran- 

 dom but after its kind and with reference to the stimulants 

 and checks that are brought to bear. One of the most im- 

 portant of these influences is light. Light has a direct in- 

 fluence upon the form and health of a tree. 

 The strongest growth of a tree's branches is 

 made toward the brightest light. The parts of a tree which 

 for any reason are shut off from the light weaken and sooner 

 or later die. 



Light. 



Fig. 17. Norway maple with character 

 istic dense crown. The foliage devel- 

 oped on this drains the roots in 

 dry weather and weak- 

 ens the tree. 



Fig 18. Norway maple after an interior 

 pruning. This modifies the shape of 

 the tree in no way while reduc- 

 ing its leaf area and thereby 

 increasing its vigor. 



PRUNING FOB VIGOR. 



