CHAP, xiii.] Fungoid Diseases of Trees 297 



respect. It occurs chiefly in damp, close localities, or on low- 

 lying tracts, wherever mists and late frosts in spring are apt 

 to prevail. It is most frequent in young crops from ten to 

 twenty years in age, though stems are still liable to become 

 infected up to about forty years. Hartig states l that the very 

 great extent to which this disease occurs in the forests of 

 northern Germany, Scotland, &c., is due to the more luxuriant 

 development of the fungus, and to the less vigorous growth of 

 the Larch ; for, though the Peziza is also to be found through- 

 out the alpine home of the Larch, the fruits of the fungus 

 generally dry up there without attaining maturity, whilst at the 

 same time the tree is better able to resist the attacks of this 

 parasite 2 . 



The first signs of the disease consist in the appearance of 

 smooth, lustrous spots or slight swellings on the stem or 

 branches, and the formation of longitudinal fissures in the bark 

 from which a slight resinous outflow takes place. This fissuring 

 soon becomes more general, and bits of bark begin to scale 

 off from the stem ; whilst small fungi appear from the fissures 

 with cup-shaped apothecia having white felty edges and bright 

 red centres. The dead, diseased parts gradually grow scurfy 

 and black ; whilst the wounds appear to deepen as the bark 

 curls up at the edges of the fissures, and the canker gradually 

 spreads up, and down, and round the stem. 



It is only at damaged parts, such as wounds from insects 

 (principally tree-lice and the mining moth), hail, bending of 

 the branches under snow or ice, &c., that the spores can 

 find a favourable germinating bed, from which the mycelium 

 may penetrate into the cortex during the non-active period of 

 vegetation. Its advance is checked during the active time of 

 the year by the formation of a tough corky layer around the 

 diseased part ; but, during the following autumn, the mycelium 

 again penetrates from the cambium into the bark, and enlarges 



1 Lehrbuch der Baumkrankheiten^ 2nd edit. 1889, P- 45* 



2 See Chapter II, p. 43. 



