INJURIOUS INSECTS, FUNGOUS DISEASES, ETC. 189 



are more or less alike, however, in their manner of entrance 

 into the trees, their subsequent development, the production 

 of their fruiting bodies, and general remedies. The false- 

 tinder fungus may be taken as a type of this class of fungi. 

 Among the trees it is known to attack are the following 

 species: the beech, the aspen, the willows, the sugar, the 

 red, the silver and the striped maples, the oaks, the apple, 

 and the hickory. 



The disease caused by this fungus is commonly known as 

 "white heart-rot. " It is usually confined to the heart-wood 

 of the tree. This is changed by the growth and develop- 

 ment of the mycelium, into a whitish, soft substance, which 

 is bounded from the healthy wood by very thin black layers. 

 These show as black lines when the trunk of the tree is sawn 

 across. The fungus gains entrance into the trunk of the 

 tree through some wound. In a majority of cases infection 

 takes place through old branch stubs. The spores germinate 

 on a stub, and the hyphae grow down through the wood of a 

 stub until they reach the heart-wood of the main trunk. The 

 destruction of the wood follows very shortly after the en- 

 trance of the mycelium into the trunk, progressing outward 

 and up and down as long as the tree lives. 



The formation of the fruiting bodies takes place usually 

 at the point where infection originally occurred. A tree 

 attacked by the fungus shows no particular change in its 

 general external appearance during the early stages of the 

 disease ; in fact, it is practically impossible to recognize a 

 diseased tree until the fruiting bodies of the fungus form on 

 the outside of the trunk. When the fruiting bodies appear 

 it may be taken for granted that the disease has progressed 

 within the trunk in both directions for two or three feet 

 from the point of infection. As the disease progresses new 



