1922-23 DEPARTMENT OF LANDS AND FORESTS 201 



cause, their nature, their effect on the wood, and factors having a bearing on 

 control The economic waste from trunk diseases in mature forests becomes 

 stupendous, and dead and wind-thrown trees add tremendously to the fire 

 hazard. Eventually systems of management may be put into operation that 

 will largely solve the disease problem, but this lies some distance in the future. 

 Meanwhile attempts will be made to utilize what has been regarded as waste 

 because of defects. Apart altogether from a sudden expansion of the volume of 

 supplies, successful utilization would at one stroke conserve and improve our 

 existing forests. A preliminary report on tests now in progress (The Paper and 

 Pulp Industry, Vol. 4, Nov. 15, 1923) arouses hope that may be practicable. 



"The cooking was done by the sulphite process in the manner in which 

 experience has shown will give the maximum yield of news grade sulphite. 



"In the results so far obtained, it would appear that in some instances, 

 contrary to previous conclusions, the decayed wood has a higher specific gravity 

 than sound wood and what is more surprising has a higher yield of pulp. 



"In one case where balsam, infected with hemlock heart rot contained 55 

 per cent, of rot, its specific gravity was 20.95 lb. per cubic foot compared with 

 20.75 lb. per cubic foot for sound balsam. In another sample of spruce which 

 contained 96 per cent, of rot of Trametes pini type the weight per cubic foot 

 was 22.3 lb. and the yield was 52.2 per cent. 



"From the limited evidence at hand, it would appear that the action of 

 the decay may have affected the lignocellulose without materially attacking the 

 cellulose in the wood. It would also appear very possible that most of the wood 

 which is normally discarded in the woods or diverted to the boiler-house as 

 fuel might be economically pulped." 



There are many common trunk diseases of balsam and spruce, of varying 

 abundance in different areas. Some are found in living trees, some in dead 

 timber. The effect produced by them on the wood of their hosts is specific, 

 and is characteristic for each kind. Some of them are characterized by a removal 

 of the cellulose from the fibres leaving them too brittle to be of any value, others 

 by a complete destruction of the fibres in advanced stages, and others by a 

 removal of the encrusting substances in the fibres without serious injury to them. 

 Of the diseases of living trees there are some that are restricted to the butt, 

 others to the main trunk. In nearly every case the characters are well-marked 

 and the various types can usually be quite readily diagnosed. The following 

 account comprises those of economic importance in the forest. 



A. Types of defective balsam. (1) Brown butt rot of balsam. — This is a decay 

 of the heart wood of the lower part of the trunk and the contiguous roots of 

 living trees. The affected heart wood loses its firm consistency, then darkens 

 more or less in colour, dries out and breaks up more or less into blocks. Cracks 

 between the broken masses may fill with indefinite, delicate, white fungus 

 sheets. The fully decayed wood powders very easily if rubbed between the 

 fingers just as does chalk or charcoal, that is, it is very friable; this is due to 

 the removal of cellulose from the wood fibres, the substance to which they owe 

 their toughness, so that what is left consists mainly of an easily powdered, 

 encrusting substance, lignin. This rot usually starts 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. It will eventu- 

 ally extend out to the bark if the tree be not wind thrown meanwhile, but as 

 yet we have no data on the time factor. 



The cause of brown butt rot of balsam was discovered about three years 

 ago in connection with our investigations. Independent observations based on 



