174 PLANT DISEASES 



Dr. Hartig, who has studied the action of this fungus 

 on oak wood, states that the peculiar effect produced on 

 the wood by the parasite is quite characteristic and distinct 

 in appearance from that produced by any other fungous 

 parasite. When the mycelium first attacks the wood, the 

 latter changes to a clear brown colour, variegated with 

 numerous white patches, somewhat resembling the plumage 

 of the breast of a partridge. At a later stage the white 

 patches become holes in the wood, lined with the white 

 mycelium of the fungus. The remaining portions of the 

 wood become darker in colour, and very hard. 



At this stage the diseased portions of wood present the 

 appearance of having been riddled by some boring insect. 

 Eventually the walls of adjoining cavities are pierced by 

 the mycelium, and finally the wood is more or less com- 

 pletely disintegrated. 



PREVENTIVE MEANS. Diseased patches should be re- 

 moved, the surface being cut away until healthy wood is 

 reached. The wound should then be protected against 

 further infection by a coat of tar. 



As the fungus is also a saprophyte, dead and fallen timber 

 should be cleared away. 



Hartig, Zersetz. des Holzes, p. 103, pi. xiii. 

 Prillieux, Malad. des Plantes Agric.^ vol. i. p. 307, figs. 121- 

 127. 



STEEEUM WOOD-ROT 



(Stereum hirsutum, Fries.) 



A fungus of very variable form, consistency tough and 

 leathery, thin, sometimes forming irregularly shaped patches, 

 lying flat on the bark or wood on which it grows ; most 



