INJURIES TO TREES. 



109 



exert too great a leverage, the losses may be reduced to a mini- 

 mum. Trees having brittle wood or weak crotches, as the Soft 

 Maple, are much more liable to this injury than those with 

 tough wood, as the willows, oaks and elms, and need more 

 pruning on this account. Evergreens are likely to be broken 



Figure .'5. Trees heavily loaded with ice after a sleet storm. 



by heavy snows that freeze on the leaves. This may be pre- 

 vented on lawn and shade trees by shaking the snow off from 

 them before it freezes. 



Frost Cracks are a rather infrequent injury caused by the 

 cracking of trees from center to outside, due to uneven contrac- 

 tion in very cold weather. It is generally accompanied by a 

 loud report. Such cracks are often eight or ten feet long, and 

 oecasionally longer. They generally close up again when the 

 wood thaws out, and during the following summer grow over, 



