MUSHROOM GROWING 



writer has found specimens with a milder 

 form of the disease offered for sale on most 

 of the larger American markets. It is not 

 possible to state positively at the present time 

 that there is but one fungus concerned, but 

 there is every reason to believe that the chief 

 types of the disease are due to one species. 

 The fungus may be provisionally called 

 Mycogone perniciosa, and it possesses two 

 known spore stages. The fungus grows not 

 only upon the mushrooms, but also upon the 

 spawn; and the sporophores of the parasite 

 are produced in large number, especially 

 where diseased mushrooms are permitted to 

 remain on the beds. It is very difficult to 

 stamp out this disease since it has been de- 

 termined that the spores remain alive even 

 under unfavorable conditions for a period 

 of more than one year, and probably for 

 several years under favorable conditions. 

 Once the disease is established in a part of 

 the house, it may be quickly spread by gath- 

 ering mushrooms, by the implements used 

 around the beds, or even by currents of air. 



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