SPRUCE DISEASES 325 



smoothed with a knife or plane, the wood inside the purple 

 zone is found to be full of small holes or pockets with white 

 linings (Fig. 64). Narrow black lines are sometimes present 

 between the pockets. The partially decayed wood between 

 the pockets is reddish in color. If the affected wood is split, 

 the pockets are found to be longer than wide and the white 

 fibers contained and the black lines between the pockets can 







Fig. 64. — Pecky wood-rot in spruce. 



be more clearly seen (Fig. 65). The decay extends eventually 

 into the sapwood and bark. 



Trees affected by this disease, as is the case with other wood- 

 rots, do not show any external symptoms until the sporophores 

 appear and limbs cr the top of the tree die due to the girdling 

 action when the sapwood is destroyed. The sporophores are 

 of two types, depending on the place from which the mycelium 

 emerges in its formation. A triangular-shaped shelving form 

 is produced at old branch wounds, where the food materials 

 gathered from an extensive region are furnished for the forma- 

 tion of a single fruiting-body. At other places where the 

 mycelium has reached the sapwood and bark, a large number of 

 small fruiting-bodies are formed which lie closely appressed to 

 the bark and only project slightly at the upper edge. The larger 

 sporophores from branch wounds add a new layer of tubes each 

 year. The upper surface is hard, black and roughened by 



