HOW WOUNDS HEAL 



135 



a tendency to die around the margins of wounds even to 

 the extent of loosening the bark. Unquestionably such 

 drying is a hindrance to healing. Another point against 

 pruning at that season is that the exposed wood is sure to 

 check more severely than if it is exposed to the air for a 

 shorter time and during a period of the year when the 

 *ap flow is more active. 



FIG. 94 SAD EFFECTS OF SLEET STORM 



This Norway maple is one of several seriously injured by a recent storm at 

 State College, Pa. It is doubtful if any pruning or training could have prevented in- 

 jury in this particular case, for the limbs are practically all broken where there were 

 no bad crotches or decayed parts. The Norway maple seems to be specially weak. 



But how about pruning during the growing season? Is 

 there no objection to it? Yes a theoretical one, at 

 least. It is claimed that pruning in spring and early 



