THE REPAIR AND REPLACING OF TREES 227 



is to run a bolt through the branches, as shown in Fig. 34, 

 by boring holes through them. With the growth of the tree, 

 the nuts holding the bolt are buried by new tissue and no 

 injury results to the tree. 



A great many trees can be saved by the practise of 

 tree surgery and their life prolonged for a great many years. 

 It is, however, work that requires great judgment and skill, 

 as every tree presents a different problem and one should 

 not entrust his trees for treatment to impostors who claim 

 to possess miraculous means of curing trees of all diseases. 



MAINTENANCE OF UNIFORMITY 



It is very disagreeable to see among a line of street-trees 

 one or two failing specimens, more so than among a group 

 of trees, or trees scattered over a large area. The task of 

 maintaining all the trees on a long street in a uniformly 

 good state is sometimes a difficult one, because of varying 

 conditions of soil and other factors. Frequently the trees on 

 a low portion of a street will not be so thrifty as those higher 

 up because the drainage is poorer and the water-table close to 

 the roots. In order to maintain in the same state of health 

 all the trees of a street plantation, some specimens may need 

 extra culture, watering, and fertilizing to enable them to 

 keep pace with their more vigorous neighbors. 



PARTIAL REPLACING 



When specimens are drooping or sickly and do not re- 

 spond to culture ; or when they are hopelessly injured in some 

 way, so that they cannot be restored, they should be re- 

 placed with new trees. The new trees should be of the 

 same species and, if possible, of the same size as the trees 



