38 FOREST TREE DISEASES. 



inches long. The disease, by killing all the branch tips 

 and the leaders, brings about faulty branching and 

 spike tops, giving the tree a shrubby appearance and 

 sometimes stunting it to such an extent as almost t<> 

 change its entire aspect. The disease also seriously im- 

 pairs the natural straight growth of young stuff. 

 Similar symptoms may be caused by late frosts or l>y 

 insects. 



BLACK COBWEB FUNGI. 



The fungi Herpotrichia nigra and Neopeckia are 

 found only at high elevations with abundant snowfall. 

 They are very common on seedlings and saplings of all 

 conifers growing in such situations, particularly on 

 lodgepole pine, incense cedar, and red and white fir, 

 and sometimes cause considerable damage. The black 

 mycelium of both fungi lives on the outside of the 

 needles. It grows under and on the snow, covering 

 the bunches of needles with a brown or black, coarse 

 cobweb, and killing them. The spores are formed in 

 very small, round, black fruiting bodies, which develop 

 on the mycelium. 



PINE GALL FUNGUS. 



Stems and branches of young yellow, Jeffrey, sugar, 

 and lodgepole pines often show a peculiar roundish 

 swelling, usually from one-half to 4 or more inches 

 in diameter and from 1 to 5 inches long. On the trunks 

 of lodgepole pine, however, the galls may be much 

 larger. The fungi (Peridermium harknessii, PI. T) 

 which causes them belongs to the rusts. The bark of the 



