1922-23 DEPARTMENT OF LANDS AND FORESTS 205 



lumber. The recognition of diseased trees is more difficult, but they can often 

 be readily spotted by their rather swollen knots and by the presence of fruit 

 bodies at the knots. 



Infection takes place ordinarily through dead or broken branches, but may 

 occur at wounds or frost cracks. Having gained entrance, the disease works 

 directly into the heart wood, and from the level attained spreads upwards and 

 downwards through the heart wood. Once established, the decay then extends 

 outwards into the sap wood in all parts throughout the affected region of the 

 trunk, and in time, if wind breakage does not happen meanwhile, the death of 

 the tree is encompassed. The outermost zone of sap wood succumbs slowly, 

 however. 



The cause of pecky heart rot of spruce and other conifers is a fungus, Tra- 

 metes pint. Its fructifications are not uncommon on living trees and are plentiful 

 on slash and fallen timber. They are bracket shaped, unless growing on the 

 under side of prostrate trunks, in which case they are effused. They are tawny 

 or chocolate brown or even blackish and vary in size from one to three inches 

 in width and one-quarter to one inch in thickness. The upper surface is irregular, 

 ridged, hairy or roughened, and the lower surface is porous. The interior sub- 

 stance is of a yellowish brown colour. 



It has already been pointed out that wood diseased to the extent of 96 per 

 cent, with pecky heart rot gives a very high yield of sulphite pulp. This is due 

 to the fact that the fibres are not destroyed by the action of the causal fungus 

 until a very advanced stage is reached. It would seem, therefore, that this 

 type of defective spruce might be extensively utilized. As a matter of fact, 

 some of the spruce now reaching the mills is affected with pecky heart rot and 

 finds its way to the digesters. Wherever trees are attacked this rot commonly 

 involves the entire length of the trunk, and in some mature stands half or 

 more of the spruce timber may be affected; utilization, therefore, would tap a 

 considerable supply now wasted. 



The control or pecky heart rot would follow along the same lines as for the 

 control of the red heart rot of balsam. What was said in connection with the 

 latter may in the main be repeated. The indications are that this disease is 

 restricted to mature timber — though at what age spruce becomes susceptible 

 has not yet been determined. If this may be tentatively assumed then two 

 procedures are suggested, both of which would result in the prevention of infec- 

 tion, one from the standpoint of the host, the other from that of the parasite, 

 and both are matters of forest management. In the one case the adoption of 

 a cutting cycle within the period of immunity would automatically ensure free- 

 dom from disease. In the other case burning of slash would prevent the devel- 

 opment of fructifications and so cut off the source of infection. The value of 

 slash burning would probably be affected by the amount of dead trunks and 

 brush on the floor of the forest included in the burning process. A combination 

 of cycle cutting and slash burning would seem to assure complete control. 



The adoption of such a system of management may be far in the future. — 

 Meanwhile, immense quantities of pecky heart rot spruce are being left in the 

 forest, timber that might possibly be used profitably from every point of view. 

 Utilization in itself will be to some extent a measure of control. 



The diseases of balsam and spruce described in the foregoing section are 

 those of importance in the forest. Some of these continue to develop in the log 

 piles, but besides them there are others not referred to which are peculiarly 

 incident to the log piles at the mills or in logs long delayed en route. An investi- 

 gation of the diseases of pulpwood timber subsequent to cutting would add a new 

 chapter of useful information. 



8 L.F. 



