250 REPORT OF THE No. 3 



found in dead standing timber, fallen trunks, stumps and slash, where they per- 

 sist as agents of destruction and as breeding centres of infection. 



Now as for control, which after all is the ultimate problem, certain facts 

 must be borne in mind. (1) There is not a uniformity of behaviour among the 

 butt and heart rot fungi — hence the various types demand individual study. 

 It is important to know the identity of each, where it fruits (whether on slash, 

 stumps, etc.), what kinds of trees it may attack, and at what ages, and how they 

 work and how rapidly. It is for these reasons that the fungi of the balsam, the 

 spruces and the pines, etc., should receive individual and detailed attention. 

 (2) Sufficient observations have been made to show that young stands do not 

 suffer from butt and heart rots. Trees will grow to merchantable size before 

 they are attacked, though they do fall a prey before they have attained their 

 maximum size. Thus if control be desired it must be considered in connection 

 with leasing and cutting plans. Control will follow automatically when an 

 adequate system of management is put into operation. The rectification of the 

 plans adopted can be effected from time to time as the- information indicated 

 above becomes available. Such plans are already being initiated by certain 

 limit holders in Quebec. This has come about through the necessity of doing 

 something if a continued supply at the present rate of consumption is to be 

 assured within competitive reach. The virgin timber left is ever more and more 

 inaccessible and is often much over mature. The harvesting and transportation 

 of this timber easily reaches a point at which the burden of added cost is in- 

 supportable. (3) To what extent slash disposal is important as a control 

 measure remains to be seen. Probably it would not much affect the butt rot 

 fungi as they can and do reproduce in connection with the stumps and roots; 

 but it would have a bearing on the control of the heart rot fungi. (4) Methods 

 of harvesting also have a bearing on the question of control. Thus a system of 

 harvesting that permits the leaving of defective and suppressed trees to remain 

 uncut would appear to favour the perpetuation of infection centres, and at the 

 same time threaten the vigour of the succeeding generation of trees. In nature 

 the strongest survive, but by such a system it is the weakest that win out. 



(b) Butt and heart rots of Balsam. — So far as I know no account has yet been 

 published of the butt and heart rots of the balsam {Abies halsamea). Rankin 

 in his "Manual of Tree Diseases" (1918) briefly discusses the butt and heart 

 rots of the American firs in general, including the Douglas fir, but of the six 

 mentioned by him it is not certain that any are applicable to the balsam. 



In any case our knowledge of the diseases of our balsam fir is meagre, so 

 that to secure information on the pathology of this tree, which is finding such an 

 extensive use in paper-making and to some extent as lumber, it will be necessary 

 to begin at the foundation and work up. 



There are three important butt rots of balsam and one heart rot. A pre- 

 liminary description of them follows. 



Type I. — This is a butt rot (the "brown butt rot" of the lumberman) found 

 in the heart wood of the lower part of the trunk and the larger roots. It may 

 extend ten to fifteen feet upwards into the trunk, but is commonly more re- 

 stricted. It is the prevalent type in some stands — in very mature stands almost 

 every tree being affected, while in other parts of the country it may be compara- 

 tively infrequent. This type is characterized by the heart wood being converted 

 into a light brownish mass due to the removal of the cellulose, which in more 

 advanced stages checks into more or less cubical masses, up to an inch or more 

 in length. On being rubbed up between the thumb and fingers these masses 

 readily pulverize just as does chalk or charcoal. The cracks between the masses 



