INJURIES TO SHADE TREES 151 



mutilation of roots. Such injuries require immediate 

 attention. The injured parts must be removed or freed 

 from ragged edges to facilitate the process of healing, and 

 in extreme cases by a corresponding trimming of the top, 

 to reduce the foliage demands to correspond with the 

 lessened power of the root system. In planning construc- 

 tion work which threatens damage to the roots of trees, 

 the harm may frequently be averted by suiting the plan 

 of work to the existence of trees. Contractors should not 

 be allowed to excavate near a tree, for any purpose, with- 

 out the approval of the civic authorities. If the commun- 

 ity has a shade tree department, the entire work should 

 be under the supervision and control of that branch of 

 the local government. Through consultation and cooper- 

 ation and through compulsion, if need be much damage 

 can be prevented. In underground construction, and even 

 in widening a street or changing a grade, it is often possible 

 to modify plans in a way to save trees which would have 

 been sacrificed if there had been no municipal control. 



Underground damage does not always start below the 

 surface, but it may come from above, as in the case of 

 salt water from ice-cream freezers emptied near the base 

 of the tree or calcium chloride or sodium chloride (common 

 salt) applied to the surface of roads and walks to keep 

 down dust. These substances are very injurious to the 

 roots of trees and other plants, as is also water in which 

 much of either is dissolved. Road oils also have to be 

 handled carefully in the neighborhood of trees to prevent 

 injury to the roots. Salt should never be used for melting 

 ice or snow on a sidewalk near trees, as the brine thus 

 formed will injure any roots that it reaches. Precaution is 

 necessary in connection with drainage from mortar beds 

 placed near trees. Water saturated with lime must not be 

 permitted to reach nearby root systems, as the lime will 

 cause serious injury. 



