254 



Minnesota Plant Diseases. 



The scaly pore-fungus rot [Polyporus squamosus (Huds.) 

 Fr.]. This is a very common pore fungus which causes a white 

 rot of timbers. It occurs abundantly in spring, forming large 

 shelves, usually in groups. The fruiting bodies are soft and fleshy 

 at first and their upper surface is conspicuously marked with dark 

 brown or blackish scaly patches (squamae). It is attached, usu- 

 ally by a short stalk, which is almost always found on the edge 

 of the fruiting body. As the latter gets older it loses its fleshi- 

 ness and becomes harder, dying the same season, so that a new 



Fig. 125.— Fruiting body of the scaly pore fungus fPolyporus squamosus), seen from 

 both surfaces. After Loyd. 



crop of fruiting bodies must be formed again the following year. 

 The pores are very large, somewhat shallow and angular and 

 often run down some distance along the stalk. This fungus is 

 usually found on dead logs or stumps but may also grow on 

 dead parts of living trees. 



The birch-fungus rot {Polyporus betulinus Fr.) This birch 

 fungus is perhaps the most common of our pore fungi. In al- 

 most every clump of birches its fruiting bodies may be found. 



