202 SHADE-TREES IN TOWNS AND CITIES 



introduced from warmer regions care has to be exercised 

 in their location and protection from frosts. 



Smooth barked trees sometimes have their trunks and 

 larger branches injured on the southwest side during the 

 winter, the injuries being characterized by the death of 

 patches of bark. During the latter part of winter and early 

 spring, when there are periods of several days of warm 

 weather, the cambium on the south side of the trunk and 

 larger limbs is stimulated to premature activity. If the 

 warm spell is followed by freezing weather these partially 

 active areas are killed. After a time the bark separates 

 from the wood and splits. The injury does not manifest 

 itself until well into the summer. The dead tissue forms a 

 favorable place for the growth of parasites that cause the 

 rotting of the wood. 



Trees can be protected from injuries caused by alternate 

 freezing and thawing by wrapping with burlap or straw. 

 When injuries have been produced the affected areas should 

 be cut away and painted with tar. 



