PINE -BLISTER. 



441 



the spring-wood which are filled with white mycelia, the 

 latter having a strong tendency to spread horizontally. The 

 sporocarps are annual, bracket- shaped, and frequently in 

 tiers. 



(e) Polyporus fulvus, Scop. It produces white rot in the 

 silver-fir, and rarely in the spruce. It is frequently associated 

 with silver-fir canker, described further on, its spores entering 

 the wood by the cracks in the cankerous swelling. The wood 

 becomes yellowish, and if clean-cut, appears intersected by 

 numerous white longitudinal bands. Narrow dark lines appear 

 at the junction between the sound and rotting wood. The 

 mycelium is yellowish, at first growing strongly, but becomes 

 later on very fine. The bracket-like sporocarps are yellowish- 

 brown above, ashy-grey below, and almost smooth. This 

 fungus is found also on cherry-trees.* 



*5. Peridermium Pini, Wallr. var. corticola. 



(Pine-blister.) 

 a. Description and Mode of Attack. 



Scots pines infested with this disease, which is very common 

 in the British Isles and called pine-blister, are termed foxy trees 

 by English foresters (Fig. 296, p. 681). Massee states that it is 

 not yet (1903) known how this 

 fungus inoculates trees, and 

 the teleutospore form of it 

 is unknown. It may be a 

 form of Coleosporium sene- 

 cionis, Fries., described fur- 

 ther on, but this is denied 

 by Cornu and Klebahn. 



Hess described the disease, ^- 2 12.-Section of pine attacked by pine- 



blister at a for seventy years, (After 



in 1866, being probably the Hartig.) 

 first to do so. 



The disease may be recognised by the compressed orange- 

 yellow coloured little tufts of the aecidia, or sporocarps, which 

 break through the bark of branches and stems of the Scots 

 pine in June, and eventually burst and set free their spores. 



* For a further account of red and white rot, see pp. 673 et seq. 



