330 



Bulletin 256. 



from the upper side, care being taken to see that the second cut 

 is made flush with the bark of the trunk (Fig, 249). The heaUng 

 process is greatly impeded by any ragged edges left by splitting or 

 careless sawing. 



An equally important factor is that the pruner should leave no 

 part of a cut or dead branch on the trunk. Old wood cells possess 

 no life, and hence, when a branch is severed, if it be of any size, the 

 exposed wood of the inner area can never heal through any growth 

 of itself. It must depend for its ultimate protection on the cambium, 



which, supplied with food from the roots and 

 leaves, grows and expands at the point where 

 the cut is made, and the new tissue rolls out 

 over the wounded surface and in time entirely 

 protects it. To get the best results, this wound- 

 ed area must be in close proximity to the 

 path of the food supply. 



Stubs soon dry out at the ends, the bark 

 loosens (Fig. 248), rolls back and falls off , leav- 

 ing the dead stub which finally rots back to the 

 main trunk and forms the beginning of a cavity. 

 This cavity, very small at first, collects water 

 in larger quantities each succeeding season until 

 finally the entire interior of the tree is rotted. 



All cuts should leave the wounded surface flush 

 with the plane of the bark on the parent branch 

 (Fig. 249). No ragged edges should be left on 

 the wood, and no part of the stub should pro- 

 ject beyond the surrounding cambium. The 

 cut surface should never be made with an axe 

 or a hatchet. Cuts can best be made with the 



Fig. 251. — A noble speci- 

 men of white oak fast out- 

 growing its period of use 

 fulness. Such trees might 



easily be preserved by 



the simplest methods of aid of a sharp saw, and a chisel with which to 



careful tree surgery 



smooth the surface, special precautions being 



taken to avoid any irregularity on the wounded surface in which 

 water may collect. 



The work of pruning a large tree should begin at the top and be con- 

 tinued as the pruner descends. In this way the operator is less likely 

 to overlook any branches that may be broken by the falling of branches 

 from above. The pruner should be careful not to break or bruise 

 healthy branches. 



Protecting 7couiicls. It has been pointed out that the natural healing 

 of a wound is the result of the growing tissue, and that in large 



