HEART-ROT CAUSED BY OTHER FUNGI 133 



into the stem. This appears to be iiivarial)ly the case, as 

 no instances have been reported in which the fungus has 

 attaclied the tree through sub-aerial wounds. The mode 

 of growth of the fungus in the tree suggests that, if it is 

 a parasite at all, it is a very feeble one, and it is extremely 

 improbable that the fungus can attack a living root, even 

 when it is wounded, unless some of the dead wood is exposed. 

 Very likely its habit is to gain entrance to the tree through 

 dead roots, but by what means it reaches dead loots is at 

 present entirely unlaiown. 



Cm-e of the disease is, of coui'se, impossible. The forester 

 must remember that he has a sixth sense in his Pressler 

 borer, a sense which he should use with enthusiasm and 

 discernment. If he watches carefully for the incidence of 

 heart-rot caused by Fomes annosus (see p. 122) he will be 

 equally guarded cigainst this other heart-rot ; at any rate 

 he will not receive his first intimation of it when the woods 

 are cut, but being warned beforehand, he will be able to use 

 his discretion as to whether the woods should be cut before 

 normal financial maturity is reached. But apart from the 

 borer, the presence of P. Schweinitzii can generally be 

 detected by its fructiiications. It fructifies much more 

 freely than Fomes annosus in the early stage of rot, and as 

 the fructifications are sub -aerial they can always 'be seen. 

 A special look-out should be maintained for the upright 

 fructifications, like that in fig. 40, which grow from the roots, 

 and may have no obvious connexion with the tree on which 

 they are feeding. These may be formed before the trunk is 

 appreciably affected, whereas fructifications are not borne 

 on the trunk itself until it is either dead or very severely 

 damaged. August is the best month in which to look for 

 these growtlis, and when they are found they should be 

 picked and destroyed in order to restrict the further dis- 

 tribution of the fungus. Of course the removal of the 

 fructification will not help the tree that is actually attacked, 

 and an investigation of the roots of the tree is advisable, 

 as if the attack is not far advanced it may be possible to 

 remove all the diseased roots, which are very probably 



