io6 Diseases of Truck Crops 



should be pulled out and disposed of by fire. Allow- 

 ing these infected plants to decay in the beds is a sure 

 means of spreading the fungus broadcast in the cave. 

 The gain from keeping the beds free from diseased 

 specimens will more than compensate for the trouble. 

 At the end of the season the beds should be thor- 

 oughly cleaned, the manure should be carried away 

 to a distance where mushrooms will not be grown, 

 although it may be used for garden purposes, since 

 the Mycogone disease is only known to attack mush- 

 rooms. After the cave has been thoroughly cleaned 

 out, it should be disinfected with the formaldehyde 

 gas method. This is carried out as follows: For 

 every thousand cubic feet of cave space use three 

 pints of formaldehyde and twenty-three ounces of 

 potassium permanganate. The potassium perman- 

 ganate is placed in two or three earthen or wooden 

 vessels, each having a capacity of one quart for every 

 ounce of permanganate. When ready for the opera- 

 tion, the mushroom house is sprinkled with water, 

 the potassium permanganate placed in the recep- 

 tacles, the formaldehyde poured evenly over the 

 permanganate, and the cave doors closed at once. 

 They are kept closed for twenty-four hours and then 

 opened to allow the formaldehyde fumes to escape. 

 All lights must be kept away from the caves while 

 they are being fumigated since formaldehyde gas 

 explodes when coming in contact with fire. Mush- 

 room houses thus treated may be thoroughly rid of 

 the Mycogone disease, but care must be taken to 

 prevent reinfection. 



