172 STUDIES OF TREES 



time and produce cavities. Cavities in trees are especially 

 susceptible to the attack of disease because, in a cavity, 

 there is bound to exist an accumulation of moisture. With 

 this, there is also considerable darkness and protection 

 from wind and cold, and these are all ideal conditions for 

 the development of disease. 



The successful application of a remedy, in all cavity 

 treatment, hinges on this principal condition that all 

 traces of disease shall be entirely eliminated before treatment 

 is commenced. 



Fungous diseases attacking a cavity produce a mass of 

 fibers, known as the " mycelium," that penetrate the body 

 of the tree or limb on which the cavity is located. In 

 eliminating disease from a cavity, it is, therefore, essential 

 to go beyond the mere decaying surface and to cut out all 

 fungous fibers that radiate into the interior of the tree. 

 Where these fibers have penetrated so deeply that it becomes 

 impossible to remove every one of them, the tree or limb 

 thus affected had better be cut down. (Fig. 118.) The 

 presence of the mycelium in wood tissue can readily be told 

 by the discolored and disintegrated appearance of the wood. 



The filling in a cavity, moreover, should serve to prevent 

 the accumulation of water and, where a cavity is perpen- 

 dicular and so located that the water can be drained off 

 without the filling, the latter should be avoided and the 

 cavity should merely be cleaned out and tarred. (Fig. 116.) 

 Where the disease can be entirely eliminated, where the 

 cavity is not too large, and where a filling will serve the 

 practical purpose of preventing the accumulation of moisture, 

 the work of filling should be resorted to. 



Filling should be done in the following manner: First, 

 the interior should be thoroughly freed from diseased 

 wood and insects. The chisel, gouge, mall and knife are 



