

FOMES 375 



roots. At a later stage, when the tree is dead, or nearly so, 

 normal sporophores, 2 to 6 inches across, are produced on 

 any portions of roots projecting above ground, and at 

 the base of the trunk. These sporophores continue to be 

 produced for many years after the tree is dead, and may 

 commonly be found on old stumps of larch. 



In this disease death is due to the complete destruction of 

 the root by the fungus. Young trees suffer most, but quite 

 old trees are also killed. 



Irregular in form, often horizontal and imbricated, 3-6 in. 

 across. Pileus convex, becoming plane, tuberculately zoned, 

 and coarsely, radially rugulose, brown, thickish, margin white. 

 Flesh whitish, tubes white, about a quarter of an inch long, 

 stratose, pores white, spores 6x4/^ hyaline. 



Flattish, biscuit-like, white sporophores are often produced 

 on the roots of living conifers underground. 



Brefeld has described a conidial form of this species, which 

 consists of a white mould, bearing numerous simple or 

 branched conidiophores, each branch terminating in a swollen, 

 subglobose bead, bearing numerous elliptical conidia on 

 slender sterigina-like bodies. Brefeld has changed the name 

 of Fomes annosus to that of Heterobasidion annosum, and gives 

 Trametes radiciperda (Hartig) as a synonym. 



Hartig has shown that the disease may be communicated 

 in a subterranean manner by means of mycelium, as where a 

 diseased root comes in contact with a sound root of an 

 adjoining tree. The mycelium also spreads underground 

 from diseased to healthy trees after the manner of the rhizo- 

 morphic mycelium of Armillaria mellea. To prevent this 

 underground extension of mycelium, it is recommended that 

 a narrow, deep trench be made round diseased trees at a 

 sufficient distance from the tree to include all the roots. The 

 mycelium, which does not travel deep down in the soil, cannot 

 pass the open trench. In a nursery, or plantation of young 

 trees, diseased specimens should be promptly removed. All 

 sporophores of the fungus, whether on living trees or dead 

 stumps, should be collected and burned, otherwise the spores 

 are a constant source of danger, and are scattered by wind, 

 mice, etc. 



Brefeld, Unters. aus dem Gessamtg. der Mykol., 8. 



Hartig, Zersetzuiigsch. des ffofces, p. 14. 



Hartig and Somerville, Diseases of Trees, p. 186 (1894). 



