Minnesota Plant Diseases. 



253 



name of the fungus is derived. In the young stages the fruiting 

 bodies are somewhat soft, fleshy or cheesy and are often eaten 

 by mushroom hunters. When older and especially under dryer 

 conditions, they become tougher in consistency and paler in 

 color. Very old masses are often found to be badly worm- 

 eaten and much of the fruiting body is reduced to a powder. 

 The fruiting bodies do not persist from one season to another 

 but go to pieces each year. New crops are produced yearly. 



FIG. 124. Fruiting bodies of the sulphur pore fungus (Polyporus sulphurous); on a dead 



oak stump. Original. 



The fungus is a common wound parasite. The wood, when 

 attacked, becomes brownish red and dries out rapidly. Slits 

 and cracks soon arise in the wood and these become filled with 

 dense masses of the thickly felted mycelium. The wood in the 

 last stages becomes brittle and the entire tree usually succumbs 

 to the attack of the fungus. 



Oaks in our state appear to suffer considerably from the 

 sulphur fungus but other deciduous trees and some of the 

 conifers may also be attacked. 



