CONTEXTS. 



Page. 



Introduction 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 Vit^e 17 



W^hitePine 18 



Tamarack 18 



Polyporus scJw:einitzii 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 



Fohjporux pinicola (Swartz) Fr 24 



Occurrence 24 



Structure of diseased wood 25 



Fruiting organ 29 



Trarnetcs pin i ( Brot. ) Fr. forma abietis Karst 31 



Occurrence 31 



Destruction of spruce wood 32 



Destnution of fir wood 35 



Destruction ( )f tamarack wood 3.) 



Fniiting organ 3(5 



Hymenium "^0 



Polyporm .vdfumis ( Bull. ) Fr 40 



Occurrence "^^ 



Structure of diseased wood "**^ 



]\Iiimte changes in the wood "*' 



Fruiting organ 



5 



