i82 PLANT DISEASES 



the 'dry rot' fungus (Merulius lacrymans) in chinks, or 

 between the dead wood and bark. 



This fungus also proves very destructive to worked 

 timber, forming snow-white expansions and long strands 

 of mycelium on the surface of beams, etc. 



Hartig suspects that the white strands of mycelium may 

 travel underground from a diseased centre, and attack 

 adjoining trees, but is not certain on this point. 



PREVENTIVE MEANS. When worked timber is attacked, 

 the only hope of success turns on being able to dry the 

 timber as quickly as possible by admitting air, otherwise 

 the fungus spreads rapidly, and quickly destroys the wood 

 after the manner of ' dry rot,' for which it is sometimes 

 mistaken in the barren condition. 



Hartig, Die Zersetzungserscheinungen des Holzes, p. 45, 

 tab. viii. 



Hartig and Somerville, Diseases of Trees, pp. 198 and 

 213. 



ROOT-ROT OF CONIFERS 



(Fomes annosus, Fries. 



= Trametes radiciperda, Hartig.) 



Probably the most destructive of fungi attacking 

 coniferous trees, occurring on species belonging to Pinus^ 

 Picea, and Abies-, has also been noted as attacking 

 Juniperus communis, Hartig has also seen it on the roots 

 of old stumps of Betula and Fagus, but doubts its occur- 

 rence as a parasite on Dicotyledons. 



The fungus is a true parasite, germinating spores gaining 

 an entrance to the living tissues of the root, and forming a 



