242 



Minnesota Plant Diseases. 



Partridge wood rot {Stereum frustulosum Fr.). This is a 

 very characteristic rot of woods and is not uncommon in Min- 

 nesota. It attacks chiefly oak and may live either as a wound 

 parasite or in a saprophytic manner on felled timber. The 

 fruiting bodies are hard and crust-like, light -brown to greyish 



Fig. 118. — Partridge wood rot. 1. 

 The fungus (Stereum frus- 

 tulosum), fruiting bodies on 

 decaying wood. 2. The cut 

 surface of the decaying wood 

 showing the characteristic 

 holes caused by the action 

 of the fungus mycelium. At 

 the edge are seen a few fruit- 

 ing bodies in section. 3. A 

 thin strip of decayed wood 

 showing holes as in 2. 4. Decayed wood seen from the end of the block. Original. 



masses, and are found in dense clusters. They are usually 

 polygonal, often five-sided, and grow from year to year, so that 

 a section through the fruiting body exhibits a layered structure. 

 On the upper side of the fruiting body, the spores are borne on 



