CONTEXTS. 



Page. 



In-trodnction 9 



Necessity for studying the diseases of forest trees 9 



Where the investigations reported were made 10 



Previous work on diseases of trees 11 



Kinds of fungi growing on forest trees and their relation to forest problems. . . 11 



Extent of destruction 12 



External evidences of decay 12 



Relation to insect attacks 13 



Scope of this report 14 



New England forests 15 



Vegetative conditions 15 



Red Spruce 15 



White Spruce 16 



Balsam Fir 17 



Hemlock 17 



Arbor Vitse 17 



White Pine 18 



Tamarack 18 



Polyponis schiceimtzii Fr 18 



Occurrence 18 



Structure of diseased wood 19 



Fruiting organ 20 



Effect of fungus on the tree 23 



Trees attacked 24 



Methods of combating this fungus 24 



Polyponis pinicola (Swartz) Fr 24 



Occurrence 24 



Structure of diseased wood 25 



Fruiting organ 29 



Trametes j)'m i ( Brot. ) Fr. forma abietis Karst 31 



Occurrence 31 



Destruction of spruce wood 32 



Destruction of lir wood 35 



Destruction of tamarack wood 35 



Fruiting organ 36 



Hymenium 40 



Polyponis mlfureus ( Bull. ) Fr 40 



Occurrence 40 



Structure of disea.sed wood 40 



Minute changes in the wood 41 



Fniiting organ 42 



5 



