1920-21 DEPAETMEXT OF LANDS AND FORESTS. 231 



succumb. The killed needles at first turn pale, but later they die, turn brown 

 and curl away from their normal orientation on the branch, continuing, however, 

 to adhere throughout the season and usually for the following year or longer. 

 The new growth throughout the entire tree is commonly more or less involved. 

 In some places the balsam is extensively affected, giving to the forest a browned 

 and ragged effect. I very much question the possibility of distinguishing this 

 blight from the work of the spruce bud worm except at close range — certainly 

 not from a moving railway car or airplane; it merits further attention. 



(c) Canker of Poplar (Aspen). 



The aspen is subject to many diseases, some of which may be so serious as to 

 render large stands practically worthless. Three of these are common in the 

 Temagami district — a leaf spot, ivhite heart rot and cariker; the last is perhaps 

 the most destructive though all three must be counted with in estimating the 

 probable yield of a stand. The aspen canker is apparently due to a parasitic 

 agent, possibly bacterial. Trunks of all sizes, branches and even small twigs are 

 liable to attack, and there a,re indications that once established the infection may 

 extend within the trunk from the point of the primary canker upwards and 

 downwards giving rise to secondary cankers at other points. Infection is especially 

 likely to occur at the bases of branches. The cankers are small at the outset, but 

 the parasite extends the area by repeatedly breaking through zones of the surround- 

 ing bark and wound callus; the result is that eventually large open cankers up to a 

 foot or more in length may be formed. This canker disease is under investigation. 



(4) Heart Eots of Coniferous Timber Trees ix the Temagami Forest 

 Eeserve — A Preliminary Note. 



Preliminary investigations have been undertaken on the heart and butt rots 

 of pines and other coniferous timbers in the Temagami Forest Eeserve. It is 

 well known that these rots are due to parasitic fungi, but as yet little is known 

 with regard to their rate of growth, the conditions that favour infection, etc. 

 Even the identity of some of them has not yet been determined by forest path- 

 ologists ; already in our preliminary studies in Temagami at least one new form, 

 heretofore not described, has come to light. From a practical viewpoint, investiga- 

 tions on the heart rots in this area are desirable for additional reasons, as follows : 



1. This area is largely covered with virgin forest, much of which is falling 

 a prey to heart rot. These appear at the present time to offer the most serious 

 problem in formulating a policy with regard to the future of the Eeserve. As 

 most coniferous trees approach maturity they become increasingly susceptible to 

 butt .and other heart rots ; a stage of maximum yield is reached after which the 

 deterioration of the forest is greater than the annual accretion, and this deteriora- 

 tion is accelerated with increasing age. There are indications that such a stage 

 has been reached in considerable areas of Temagami, and these should be carefully 

 examined. 



2. The balsam of the Temagami Eeserve is especially susceptible to butt rots, 

 to such an extent that little of it attains merchantable size. A very high per- 

 centage of the balsam of all ages is affected, probably not less than 75 per cent. 

 The most serious features in this connection relate (a) to the balsam as a breeding 

 ground for heart rot fungi that attack maturing pine and spruce ; in some places 



