202 REPORT OF THE No. 3 



comprehensive, carefully executed laboratory tests, made by Dr. E. E. Hubert 

 of the U. S. Forest Products Laboratory, fully confirm our findings. The cause 

 is a fungus, Polyporus balsameus, the fructifications of which make their appear- 

 ance on the surface of the trunk near the ground, or on the exposed wood where 

 a diseased tree has cracked or broken over. They are not especially common, 

 but by no means infrequent during wet summers or early autumns. They are 

 ■ small shelf-like bodies, occurring singly, or more typically, several closely super- 

 posed, thin, tough, white below, and white to brownish on the upper surface. 

 The upper surface is rather faintly zoned. They vary in size from one-half 

 inch to one and one-half inches in width. 



Brown heart rot when developed to the friable stage is certainly of no 

 value for pulp, and in earlier stages the affected fibres are weakened to a greater 

 or less extent. The actual loss in cutting operations usually amounts to a short 

 butt log. How much should be rejected would appear to depend in part on 

 floating capacity (of which no definite data are at hand) and in part on the 

 relative amounts of sound and diseased wood. The latter is valueless. The 

 principal economic loss caused by brown butt rot results from windfalls due 

 to the weakening of the base of the trunk; and with openings once made in the 

 forest the destruction may be very great, involving sound as well as diseased 

 trees. 



(2) Feather rot of balsam. — Feather rot is a decay of the heart wood of the 

 lower part of the trunk and the contiguous roots of living trees. It is a butt 

 rot. The affected wood as it decays changes in colour to clay or buff colour. 

 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 delamination or flaking of the wood, 

 the decayed wood readily falling into sheets, each sheet consisting of an annual 

 ring. The surfaces of the sheets are more or less etched. In some cases there 

 is a tendency for radial perforations to form quite early in the course of decay, 

 often before there is any indication of delamination. Eventually there is a 

 shredding of the wood due to radial deepening of the longitudinal furrows. 

 This continues until the wood is reduced to cottony shreds, with at the same 

 time a fading of colour. In extreme cases the shreds may disappear to a greater 

 or less extent, leaving the butt hollow. One of the curious features of feather 

 rot is the frequent occurrence, especially in the advanced stages, of small black 

 spots. 



This rot usually begins at wounds or defective spots on the inner faces 

 of the main roots just below the stump. It develops upwards into the trunk 

 but for not more than a few feet as a rule, perhaps not as far as does the brown 

 butt rot. In the course of time it extends out to the bark if the tree be not 

 wind-thrown meanwhile. Feather rot continues to spread through the wood of 

 dead or fallen trees until at last the wood of the entire trunk may be converted 

 into a wet, stringy, yellowish mass. 



While the detailed appearance of feather rot is somewhat variable, its 

 general features are so well marked that it cannot be mistaken. It may be that 

 the variation is due to the action of different fungi, in which case the type would 

 consist of two or more sub-types; or the variation may be due to the action of 

 secondary fungi following up the primary fungal agent. Further research alone 

 will settle this point; but so far as I have been able to observe, the question is 

 not one that enters into the problem of utilization. Our investigations have 

 determined that a fungus, Poria subacida, produces feather rot. The fructifi- 

 cations make their appearance on the surface of the trunks of much decayed 



