FOREST INSECTS AND FUNGI 127 



susceptible to its attacks, the spruces next and the balsam least. 

 It is a common and extremely dangerous disease, entering 

 living trees, old enough to form heartwood, through wounds or 

 any opening in the bark and continuing to grow even after the 

 tree is dead where moisture conditions are favorable. From the 

 point of entry it spreads up and down the trunk, working both 

 in the heartwood and the sapwood, except in white pine, where 

 it flourishes only in the heartwood. Finally even the roots and 

 the larger branches may be infected. As the wood is not entirely 

 destroyed by the fungus the tree remains standing, but is so 

 weakened that eventually it is broken off by a strong wind. The 

 lumber value of the infected portion is entirely destroyed. 



The fungus can be identified because the diseased wood is 

 honeycombed and is filled with small holes. These holes often 

 have a shiny white lining, and between the holes will be thin 

 layers of wood only partially destroyed. The best outward 

 indication of the disease is the pitch which exudes on the bark, 

 sometimes in considerable quantities. 



The fungus 1 is spread by spores blown by the wind. 



These come from fruiting bodies located usually at old knot 

 holes and on the stubs of dead branches, although on spruce at 

 least the fruiting bodies may form in dry crevices of the bark. 



The light reddish-brown color of the lower surface of the 

 fruiting bodies is characteristic, but their form varies from a 

 bracket shape to that of a plate, following the configuration of 

 the trunk or branch. 



There is no practical method for use in forestry of combating 

 Trametes pini. Diseased trees, as soon as discovered, should 

 be cut and utilized, but as such trees are often scattered it is not 

 always possible to remove them. If all diseased trees could be 

 discovered quickly and removed the loss from this fungus would 

 be greatly lessened. Since the disease is worse in crowded 



1 A detailed description of Trametes pini will be found in U. S. Division of 

 Vegetable Physiology and Pathology, Bull. 25, entitled, "Some Diseases of New 

 England Conifers," by Von Schrenk, and Vt. Exp. Sta. Bull. 191. The Red Rot of 

 Conifers, by F. H. Abbott. 



