SPRUCE DISEASES 317 



Brown Felt-Blight 



Caused by Herpotrichia nigra Hartig and H. quinqueseptata Weir 



Although this disease has been noted in European literature 

 as important on spruce, juniper, larch and mountain pine for 

 many years, it is only recently that any mention has been 

 made of it in the United States. In this country, as in Europe, 

 it is found only at high altitudes from six to eleven thousand 

 feet above sea level. So far, it is reported in the northwestern 

 states on species of spruce, fir, juniper, cedar (Libocedrus), 

 arbor-vitse and hemlock. A similar disease which cannot be 

 distinguished as to its symptoms from this one occurs in the 

 same region on species of pine. The brown felt-blight of pine 

 is caused by a different species of fungus, however, and is 

 discussed briefly under pine diseases, on page 271. Both in 

 Europe and the United States, the damage caused by this 

 blight is considerable and young trees and the lower branches of 

 older trees suffer most, although in some localities entire stands 

 are badly affected and have the general appearance of having 

 been swept by fire. Even when the damage is not so severe, 

 the annual increment of wood is lessened and the general health 

 of the trees impaired. 



Symptoms. 



A brown felt-like mass of mycelium spreads extensively over 

 the leaves and twigs, causing them to become matted together 

 and completely covered (Fig. 16, page 131). In the case of 

 young trees, all the foliage may become covered. The lower 

 branches of older trees are more commonly affected than the 

 upper part. The mycelium enters the leaf-tissue and the leaves 

 are killed through the combined action of the internal food- 

 gathering mycelium and the thick covering over the leaves 

 which shuts out the light and produces a high humidity. The 

 mycelium may pass from one tree to another where branches 



