DISEASES OF BOOTS, ETC. 47 



POLYPORUS SCHWEINITZII. 



Polyporus scJiweirdtzii (PI. XIII) is one of the most 

 serious enemies of Douglas fir, and also occurs on cer- 

 tain pines and on white fir. It continues to live and 

 fruit long after killing its host, and rapidly destroys 

 the economic value of the timber. The disease gen- 

 erally appears on the roots and lower parts of ma- 

 ture trees and spreads upward. The decayed wood is 

 reddish brown, with very thin, resinous crusts of my- 

 celium. Later it becomes friable, and is easily crushed 

 between the fingers to a yellow powder. The presence 

 of the disease is often disclosed by resin flow on the 

 bark at the base of the tree. The annual fruiting 

 bodies, which usually appear on old wounds at the base 

 of a tree, a little above the ground, or on the soil coming 

 from dead tree roots, have a characteristic short, thick 

 stalk, are rather large, reddish to dark rusty brown in 

 color, with a yellow margin, cheesy when young, and 

 soft and corky when dry. The porous underside of 

 fresh fruiting bodies is dirty green, and turns deep red 

 brown when bruised. The old dry fruiting bodies from 

 dead tree roots closely resemble old cow dung. 



RED-BELT FOMES. 



Eed-belt fomes (Fomes pinicola, PL XIV) is the 

 commonest timber-destroying pore fungus in Califor- 

 nia, attacking all the important conifers, except incense 

 cedar, juniper, redwood, and bigtree. The perennial 



