MUSHROOM PESTS AND THEIR CONTROL 9 



tion is necessary. The manure in the beds will reach a much higher 

 temperature during this time but should not be allowed to exceed 

 145°. A temperature of 120° for 48 hours will eradicate the "bubble" 

 disease (mycogone) also. 



During the heating of the compost in the beds much moisture is 

 driven off. In basements of dwellings it is inadvisable to try to reach 

 a high temperature unless the room can be sealed tightly enough to 

 prevent the moisture and heat from warping the floor above. 



FUMIGATION 



When the temperature of the beds has reached its maximum the 

 house should be fumigated with either sulphur or cyanide before the 

 spawn is placed in them. 



SULPHUR 



Sulphur should be burned at the rate of iy 2 to 2 pounds per 1,000 

 cubic feet of air space. The amount used per 1,000 cubic feet, how- 

 ever, should not exceed 2 pounds. Within 5 or 6 hours after the 

 sulphur has finished burning the ventilators should be opened, the 

 house allowed to air out, and then closed again to prevent too rapid 

 cooling. Owing to the slow rate of burning and the rapid absorption 

 of gas by the moisture in the house, it is doubtful if an efficient 

 fumigation is ever attained by burning sulphur in pans within the. 

 house at peak heat. The outside burner previously described (p. 5) 

 will give much better results. 



Sulphur fumigation has a tendency to raise the acidity of the first 

 one-half inch or so of the beds (the limit of penetration of the gas), 

 and a green mold often follows. This soon disappears, however, and 

 neither it nor the increased acidity of the surface of the beds seems 

 to have any harmful effect upon subsequent mushroom growth. 



When a house to be fumigated is immediately adjacent to another 

 in production, every precaution should be taken that the fumes do 

 not reach and damage the growing mushrooms. The ventilators of 

 the house in bearing should be open, and the house in heat should be 

 fumigated only when there is no wind, or when the wind is blowing 

 away from the house in bearing. In case of a double house, the other 

 half of which is in bearing or spawned, it is better to use cyanide 

 rather than to risk damage from sulphur fumes. 



HYDROCYANIC ACID GAS 



The three materials in common use for hydrocyanic acid gas 

 fumigation are calcium cyanide, sodium cyanide and sulphuric acid, 

 and liquid hydrocyanic acid. 



Since the application of liquid hydrocyanic acid requires special 

 equipment, as well as special training on the part of the operator, 

 and since it gives little better results than calcium cyanide or sodium 

 cyanide and acid, it may be left out of this discussion. 



The use of calcium cyanide at the rate of 1 pound per 1,000 cubic 

 feet of air space is at present the most common method for fumi- 



18058°— 38 2 



