INJURIES TO SHADE TREES 155 



damage, not by keeping the tree warm as many suppose, 

 but by protecting it from the sun's rays during the day, thus 

 preventing so much variation in temperature between day 

 and night. This is especially helpful when the day tem- 

 perature in the sun is well above freezing and the night 

 temperature several degrees below. Shading the south 

 side of a trunk is often sufficient to protect against frost 

 cracks or sun scald. 



In old trees it frequently happens that the bark near 

 the base comes loose from the trunk, preventing a proper 

 flow of sap downward and forming a hiding place for 

 insects which endanger the life of the tree. Loosened 

 bark may be detected by tapping with a metal object. 

 If the taps produce a hollow sound, easily recognizable 

 when contrasted with the sound of taps on a healthy tree, 

 the loosened bark must be removed and the wound treated 

 with some protective material as already discussed. 



For the repair of all injuries, and even for the chance 

 to live, the street shade tree needs and merits a friend. 

 In a town or city where there is a shade tree department, 

 the friendly offices of healing and repair are best exercised 

 by the constituted authorities. Where there is no such 

 department, the tree must look to its next of human kin 

 the property owner or nature lover who transplanted it 

 into its strange environment and who profits most by its 

 existence and development. For him to withhold the 

 needed help is to nullify the effort of planting. Such 

 neglect is short-sighted and inexcusable. 



