155 
INJURIES TO SHADE TREES 
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. 
