1921-22 



DEPARTMENT OF LANDS AND FORESTS 



251 



may partly fill the indefinite delicate white sheets of the fungus. This decay 

 will eventually extend out almost to the bark, so that only a very thin shell of 

 sound wood may remain. Such a butt rot is known to occur in all of the conifers, 

 both in Europe and America. It has, on inconclusive grounds, been commonly 

 referred to a fungus botanically known as Polyporus Schweinitzii. But our 

 studies both in the field and in the laboratory so far have connected it with a 

 fungus called Polyporus balsameoiis Peck. Culture studies have borne out this 

 conclusion and association of the fruit bodies with the decay in the forest. 



It is, of course, possible that P. Schweinitzii or even some other fungus may 

 at times attack balsam, causing a similar type of decay. If such findings be 

 established, then this type will be subdivided into Type la, lb, etc. ^^M^VK^-tj, 



Types II and III. — These are also butt rots, and are probably not dis- 



Fig. 9. — Young balsam attacked by a fern rust (Uredin opsis). 



tinguished from one another by the casual observer. They pass under the name 

 of "feather rot" because of the light coloured, shredded or flaky rot that char- 

 acterizes the later stages. This decay does not extend as far up into the trunk 

 as Type I, but causes just as great a weakening of the butt. It is very abundant 

 in some localities. 



Type II is described in my field notes as follows: The newly decayed wood 

 is clay colour or tawny olive, later a cinnamon buff. It is soon marked by tiny 

 longitudinal pockets or cavities of indefinite length arranged in close concentric 

 series, typically a single row in the fall wood of each annual ring. This results 

 in the lamination or flaking of the wood, the decayed wood readily falling into 

 sheets, each sheet consisting of an annual ring. The surfaces of these sheets, 

 as one might expect, are etched. Eventually there is a shredding of the sheets 

 due to the radial deepening of the longitudinal furrows. This continues until 



