326 Bulletin 256. 



require a greater or less amount of pruning to retain it in a normal 

 condition, and it can never develop to its maximum beauty and size; 

 therefore it should be replaced by a more hardy species which will not 

 require so much care and protection. (See page 463.) 



B. Pruning of street trees, and tree surgery. 



The presence on street trees of ngly wounds, large cavities, and 

 the projecting stubs of dead branches, are indications that such trees 

 have been grossly neglected or carelessly treated. Improper treatment 

 is so common that losses through the neglect of pruning or the practice 

 of incorrect methods assume enormous proportions. 



The amount of pruning that is necessary to preserve a tree in its best 

 condition varies greatly with the species and type of the tree. It is 

 quite as easy to prune a tree too often and too much, as to prune not 

 enough. In general, trees along highways require very little attention; 

 but what attention is needed must be given at the proper time and in 

 an intelligent way. Pruning may be undertaken for the follow- 

 ing purposes: 



(i). To remove dead wood and injured branches. 

 (2). To secure a stronger and more vigorous growth. 

 (3). To open up the head of the tree and to reduce competition 

 among the branches. 



(4). To adapt the species to street purposes as shade trees. 

 (5). To control the production of flowers. 



(i). Removal of dead wood and injured branches. Old trees, crowded 

 trees, and those that have been subjected to the detrimental influences 

 of gas and overhead wires, require a certain amount of pruning to pre- 

 serve them in a normal condition. In such cases, the practice should 

 be to remove each year dead or dying branches, and to cut back below 

 the point of injury those branches that have been injured in any way. 

 Trees that have developed the condition known as "stag-head," which 

 is evidenced by a dying out of the top, should have the dead parts re- 

 moved and the other parts cut back slightly to conform to the shape 

 of the tree. 



(2). To secure stronger and more vigorous growth. The significance 

 of this operation is explained by saying that if we remove a part of a tree, 

 the food supply which would have gone to that part is distributed through- 

 out the remaining parts of the tree, and in consequence these parts 

 make a more vigorous growth. While this is a common practice among 

 trained tree pruners for rejuvenating old and weak specimens, and to 



