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CIRCULAR 2 51, U. S. DEPARTMENT OF AGRICULTURE 



Monilia fimicola Cost, and Matr., which produces a grayish spore dust 

 throughout the interior of the compost. When this fungus is abun- 

 dant in the beds the mushroom mycelium rarely grows more than a 

 few inches from the spawn piece and a total crop failure often 

 results. In some cases the origin of serious infestation with this 

 mold has been traced to contaminated brick spawn. Usually severe 

 outbreaks are due to insanitary conditions around the mushroom 

 house or to a wet, soggy condition of the manure at filling time. 



The truffles disease is characterized by the development of cream- 

 colored wefts of fungus mycelium which appear under the side- 

 boards and in the manure at about the time of casing. Unlike 

 the plaster mold, the truffles fungus Pseud obalsamia microspora 

 Diehl and Lambert seems to stimulate rather than prevent the run 

 of spawn in the early stages of the crop. A few weeks later, how- 



Figuee 15. — Truffles disease in a mushroom bed 



ever, when the truffles fungus matures and forms wrinkled fungus 

 bodies in the manure and on the soil, the parts of the beds infested 

 with truffles become barren and the mushroom mycelium almost com- 

 pletely disappears. (Fig. 15.) The source of this fungus is not 

 known, since it has not yet been found outside of mushroom houses. 

 However, the nature of the fungus and the history of the disease 

 suggest that it lives in the soil and is carried into the house in the 

 compost. There is also some evidence that it may remain from one 

 crop to another in the bed boards and that high temperatures and 

 an overwet condition of the manure favor its development. The 

 spores are probably distributed principally at the time of emptying 

 the beds. 



It would seem advisable, if a house has been infested with truffles 

 disease, to take the following precautions: Thoroughly fumigate 



