THE MYCOGONE DISEASE OF MUSHROOMS AND ITS CONTROL. 6 



IDENTITY OP THE FUNGUS. 



The common identity of the fungi studied by different investigators 

 in relation to the disease of mushrooms has not been established, but 

 it is interesting to note that in each study one of the three concerned 

 in the life history of the fungus causing the mushroom disease, e. g., 

 Mycogone, Verticillium, or Hypomyces, is the subject of investigation. 

 Owing to the similarity of the fungus causing the disease to certain 

 stages of diseases of wild species of mushrooms, Magnus called the 

 fungus Hypomyces pemiciosus. No technical description was given 

 by this author and the fungus was only a hypothetical stage of 

 Hypomyces. 



Cooke (1889) in England identified the fungus which was causing 

 considerable loss to mushroom growers as "a species of Mycogone not 

 unlike Mycogone rosea in many of its features, but referable to 

 Mycogone alba," notwithstanding the fact that he described the larger 

 cells of the Mycogone spores as becoming amber colored. 



In Vienna, Austria, Stapf (1889) described a disease of cultivated 

 mushrooms, which was attributed to Verticillium agaricinum Corda, 

 a conidial stage of Hypomyces ochraceus Pers. Stapf found several 

 spores of Mycogone, but could not connect them with Verticillium. 



Prillieux (1892) described a disease of mushrooms and identified it 

 as Mycogone rosea, which by analogy he considered a conidial stage of 

 Hypomyces linkii Tulasne, although the perfect stage of the fungus 

 had never been observed. 



In the same year Costantin and Dufour (1892a) published a note on 

 the disease then known as *'la molle." They described the macro- 

 scopic and microscopic characters of the disease and stated that the 

 fungus is very similar to Mycogone cervina, though it differs in habitat, 

 or host plant. Two types of modification of the mushroom caused by 

 the fungus are described. In the first type the cap, stipe, and gills 

 are well defined, though the presence of the disease is indicated by a 

 stipe swollen at the base, swelling of the gills, and distortion of the 

 cap. The second type of the disease is manifested by an early arrest- 

 ing of the development of the mushroom, the cap is rudimentary or 

 entirely lacking, and the stipe, or stem, is swollen to such a size that 

 the affected mushroom has the appearance of a puffball. On the dis- 

 eased mushrooms of the first type Mycogone and Verticillium spores 

 were found. The Verticillium spores were long, cylindrical-oblong, 

 and sometimes two celled. The relationship of these two forms, 

 Mycogone and Verticillium, was established by finding the two kinds 

 of spores growing on the same mycelium. The second or puffball-like 

 type of diseased mushrooms has only a Verticillium with small 

 unicellular spores, microscopically quite different from the Verti- 

 cillium of the first type. 



