240 



THE PROTECTION OF WOODLANDS. 



Fig. 58. 



and often making them fall off, and L. nervisequium the 2-year-old leaves 

 of Silver Fir branches, turning them brown and causing leaf-shedding. 



Remedy. Spraying or cutting and burning diseased shoots, but neither 

 practicable extensively. 



The Larch leaf - shedding disease, Sphcerella laririna, attacks the 



foliage of poles or trees. 

 In June or July infect- 

 ed leaves turn brown- 

 spotted and soon fall 

 off, and in wet years 

 most of the foliage is 

 shed by August. The 

 only way to stop the 

 disease spreading is to 

 cut and remove infected poles or trees, 

 and burn the diseased foliage, else the 

 small black conidia forming spread the 

 disease in wet weather. 



The Larch canker- or blister- 

 fungus, Peziza Willkommii (syn. 

 Dasyscypha calycina) (Fig. 58), 

 the most destructive tree-disease 

 in Britain, is saprophytic on dead 

 Larch twigs, and as a parasite 

 chiefly attacks Larch (also Pines 

 and Firs) of 7 to 15 years old. 

 Japanese Larch is still much less 

 liable than common Larch to 

 attacks of insects and of this 

 fungus, though no longer im- 

 mune. Larch is never immune 

 from attacks, though after thick 

 bark forms attacks are confined to young branches. It is a 

 wound-parasite, and spores only germinate where punctures or 

 greater wounds have been made by insects, hail, gnawing, &c. 

 The earlier the attack, the more serious it is. Poles of 7 to 12 

 years are usually badly deformed or killed outright. On older 



Larch Canker. 



a. Dead wood with resin outflow. 



b. Cup-shaped sporophores of fungus 



