THE DISEASES OF CONIFERS. 



131 



A complete list of the parasitic fungi which injure the Pines 

 would carry us too far, and I must content myself with the 

 following selection of them. 



Some of the most mischievous are Trametes mdiciperda, 

 {Polypoms cuinosus, Heterobasidion amwsum), Tr. Pini, Poly- 

 ])orus mollis, F. vaijorarius, P. Schweinitzii, and Agaricus 

 melleus. 



These fungi, which are distinguished by technical characters 

 the discussion of which must be passed over here, differ consider- 

 ably in their mode of action and manner of inducing disease,* but 

 they all agree generally in that they eventually destroy the timber 

 of the trees, by dissolving and consuming the structural elements 

 which compose it. Now since the timber of the Pine furnishes 

 (1) the channels up which the water and nutritive materials 

 have to pass from the roots to the leaves, and (2) the supporting 

 columns by the strength of which the crown of foliage can alone 

 be held aloft and exposed to the light and air, it follows that 

 such destruction results in disease and death to the tree as a 

 whole. 



Trametes radiciperda, now known very thoroughly from the 

 recent magnificent researches of Brefeld,f who also proposes to 

 re-name it Heterobasidion annosum from the remarkable conidial 

 forms which he has discovered, attacks the living roots of 

 P. sylvestris, P. Strobus, and others, sending its snow-white 

 mycelium beneath the cortex, and travelling thence up the stem, 

 to finally penetrate the wood by way of the cambium and 

 medullary rays. The rotting of the wood rapidly follows, with 

 symptoms so peculiar that the presence of this fungus can be 

 concluded "with certainty from them. Owing to the reddish 

 discoloration of the timber which results, this disease has been 

 termed the "red-rot," a name which involves confusion, how- 

 ever, as several other similar diseases of timber cause such dis- 

 colorations. 



This disease is extremely difficult to eradicate, because the 



mycelium travels from root to root in the soil, and the spores 



that the roots of certain Conifers may have hyph® of G aster omijcetcs attached 

 to them, though, so far as I can discover, they do not induce diseased con- 

 ditions in the tree as a ^yhole. 



* For a more detailed account of these matters see " Timber and some 

 of its Diseases," by H. Marshall Ward, M.A., F.E.S. (Macmillan & Co.) 



•{■ "Unters. aus dem Gesammtgebiete der MykoL," H. viii., 1889, p. 154. 

 See also E. Hartig, " Zersetzungserscheinungen des Holzes " (Berlin, 1878), 



K 2 



