196 PLANT DISEASES 



removed, the surrounding wood cut away to the depth of 

 an inch round the wound formed, so as to remove the 

 mycehum and conidia that may be present. The cut 

 surface of the wood should then be washed with a saturated 

 solution of corrosive sublimate in spirit, and afterwards 

 painted over with tar. If the broken end of a branch is 

 attacked, it should be cut off far enough behind the point 

 of attack to make certain of removing the portion of wood 

 containing the mycelium of the fungus, and this should 

 include six inches if practicable ; for, although the fruiting 

 portion of the fungus is an annual, its mycelium, when 

 once in the wood, appears to extend its ravages from year 

 to year. As a matter of course the fungus should be 

 destroyed whenever it appears, as its spores and conidia 

 are carried to a considerable distance by wind. By destroy- 

 ing the fungus is not simply meant removing it from a tree 

 and crushing it under foot, which only in reality means 

 spreading its spores; it should be either burned or buried, 

 the first remedy being most effectual. 



Hartig, Die Zersetzimgserscheinungen des Mokes, p. 109, 

 tab. xiv. 



Marshall Ward, Timber and some of its Diseases, p. 165. 



Various other species belonging to the Polyporeae have 

 been proved to be parasites, or are suspected of being 

 such. 



Polyporus schwei?iitzii, Fr. — A large brown fungus with 

 a coarsely velvety pileus and soft brown flesh, pores 

 large, irregular. Superficially resembling P. liispidiis, but 

 distinguished by the short central stem. It attacks the 

 larch, Scots fir, and Weymouth pine. 



