84 



( d ) Sapwood Rot Fungi. 



( I ) Fomes fomentarius. This fungus is very common in Can- 

 ada, occurring cliiefly on the beech and the birches. The fruit bodies or 

 sporophores are hoof-shaped, the upper surface is smooth and grey in col- 

 or and more or less marked with concentric ridges. The lower surface 

 is reddish-brown, and soft and velvety \vhen young. The decay caused by 

 this fungus begins in the sapwood and proceeds in\vard, so that the cen- 

 tre of the tree m.ay remain sound for some time after the outer part has 

 decayed. Some botanists regard this fungus as truly parasitic on living 

 trees, others think it is saprophytic, attacking only weakened or dying 

 trees and causing their decay. 



( 2 ) Polyporus betulinus This fungus may be classed with 

 the preceding as a sapw^ood rot fungus. It occurs on the various^ species 

 of birch. The sporophores are conspicuous, more or less white in color, 

 convex above and somewhat hollo v/ed below. The decay caused by this 

 fungus is similar to that described for Fom.es fomentarius. It is very 

 common on birch , especially on trees that have been injured by fire or 

 weakened in some other way. 



A number of other fungi attack dead or dying trees and bring about 

 their decay. Some of them are probably parasitic and attack living trees. 

 Further study is necessary to determine whether they are truly parasitic 

 or not. The follow^ing are am.ong the most common in Eastern Canada. 



Fomes applanatus, Polystictus versicolor, Polystictus pergam^enus, 

 Polyporus adustus, Polyporus cinnabarinus, Daedalia quercina, Daedalia 

 unicolor, Polyporus pinicola. 



Methods of Control. As the spores of parasitic pfore fungi 



find entrance at wounds care should be taken to avoid injuring trees. 

 Wounds from pruning or from other causes should be covered with some 

 protective substance. Paint is most commonly used, but is probably not 

 effective unless renewed frequently. Other -wound dressings used are tar 

 and meltedi asphaltum. Those interested in this matter should consult 

 Circular No 126, "Dressing for pruning Wounds on Trees" issued by 

 the Ohio Agricultural College. 



The protection of wounds may not be practicable in forest areas. 

 Here the chief means of control -will be the removal of diseased or dead 

 trees or parts of trees. Many of these bear fruiting bodies of the fungi 

 which produce each year vast numbers of spores. These spores are car- 

 ried by the wind and thus the diseases are spread. The destruction of the 

 diead and decaying diseased timber -will also help to hold in check' many 

 insect enemies of trees. 



