Additional Papers. 323 



the shade trees by direct contact with high potential wires or by chop- 

 ping off the branches. 



When trees have become spHt at the crotches by storms, they may 

 often be saved if the separated members be Ijolted together. The bolt 

 is run through a hole bored through the separated branches and drawn 

 tip with a nut. Both the nut and the head of the bolt should be large, so 

 that they will not draw into the wood. 



Pruning. — At the time shade trees are set out, they should be care- 

 fully pruned, with a view of helping them to develop into symmetrical 

 trees; after that a little pruning from year to year is all that is required. 

 In the case of elms and trees which have been brought from the woods 

 it is a good plan to cut them off about ten feet above ground and trim 

 the side branches back to stubs. If the trees have well formed heads, 

 they may be simply shortened in when transplanted. 



The Silver Maple, like other soft wood trees, needs particular atten- 

 tion at this time. Preferably, it should be pruned to form a main central 

 axis with numerous smaller secondary branches arising along the main 

 axis. In cases where this cannot be done, the tree should be trained to 

 form a symmetrical head, in which no large crotches are allowed to 

 form. After the first few years street trees will need but little pruning; 

 they should be examined each spring, however, to see what is neces- 

 sary. Trees may be pruned about the time the buds start in the spring 

 and from that time until they are in full leaf. During this time the 

 growth is active and the wounds heal rapidly. 



Some general principles of pruning for all trees may be suggested. 

 If the tops of the trees are to be shortened in, it should be done grad- 

 ually. No branch more than one inch in diameter should be cut off, 

 but the heading in should be repeated from year to year, until the tree 

 is of the desired shape. The practice of cutting off the larger limbs 

 squarely at the top is very injurious, for reasons already noted. It 

 .should never be permitted. 



When removing a branch, cut it close down at the shoulder with a 

 sharp saw, so as to leave no stump. The adjoining cambium cells will 

 then be able to grow over the wound and close it. In case the limb 

 is over two or three inches in diameter, it should be cut oft' a foot or 

 more from the base, to prevent it from splitting or peeling back the bark ; 

 then the stump should be cut off close up to the main trunk, leaving a 

 smooth surface. 



As soon as dry enough, all large cuts should be painted as directed 

 below. 



No street trees should be allowed to develop branches within eight 

 feet of the ground, for the safety and convenience of pedestrians. 



