Street Trees. 



329 



reel fnethod of 

 making a cut. 



and early April is preferable. An exception to this, however, occurs 

 in the case of maples. These trees bleed very freely when cut in 

 early spring, and professional pruners have found 

 that the best season for pruning them is during 

 the summer months. This loss of sap is not recog- 

 nized as being injurious to the tree; but the wounded 

 surfaces may be protected more easily in summer 

 pruning. 



In choosing the season for pruning trees, it must 

 be kept in mind that the healing of the wounds de- 

 pends on the growth of the cambium. We see, there- 

 fore, that in very dry and severe climates, the exposed 

 freshly cut and unprotected tissue may be killed back 

 during the winter months. On the other hand, 

 wounds made just previous to the growing season and F'g. 249. — Thecor- 

 which are adequately protected, will become partially 

 or wholly covered by the new layers from the cam- 

 bium during the same spring, and in a short time the cut will be com- 

 pletely healed over. It is unreasonable to expect a large wound to heal 

 in a single season; but the ordinary wound on a tree which has been 

 pruned judiciously since planting, will be healed in a single season suffi- 

 ciently well to warrant its being left unprotected artificially thereafter. 



Making the cut. This operation more often than 

 any other, has resulted in fatal injury to the tree. 

 Authorities agree that most of the injuries to shade 

 trees from fungi may be traced directly to poor prun- 

 ing and mechanical injuries, and they have shown 

 that there are various wound fungi that develop 

 only as a result of poor pruning. Incorrect methods 

 of antiseptic protection have also aided in bringing 

 about the evil results. 



Removing large branches may be attended by in- 

 injury to the tree by breaking and tearing strips of 

 Fig. 250. — Insuffi- bark and wood from the trunk below their points 

 'l7cLtaTwea- ^^ attachment (see Fig. 246). To avoid this,twocuts 

 thering leave an are made, first one on the under side of the branch, 

 otherwise clean about one foot from the main trunk, and the other 

 cay. ° ^'^ "^^ upper side of the branch (Fig. 247), thus re- 



moving all but a stub extending out from the trunk. 

 The stub is then removed by first making a slight cut on the under side 

 to insure against any possible splitting of the wood, and then cutting 



