MUSHROOM PESTS AXD THEIR CONTROL 11 



10 to 20 minutes after the cyanide is scattered. In view of the deadly 

 nature and the rapid evolution of this gas, every precaution should 

 be taken against accidents. No one should be permitted to open 

 calcium cyanide or scatter it without wearing an approved gas 

 mask equipped with a canister especially designed for that gas. 

 In the case of a single house, the chemical should be scattered in 

 the central alleyway as evenly and quickly as possible, beginning at 

 the back of the house and working toward the door. Special care 

 should be taken to see that the alleyway is clear of obstructions before 

 the fumigation is begun, as a stumble over some obstacle while walk- 

 ing backward and scattering the cyanide might easily result fatally, 

 even though the workers are wearing gas masks. In the case of a 

 double house the material is scattered in the two main alleyways, 

 the workers starting together at the far end and working toward the 

 doors, timing themselves so as to reach the doors simultaneously. 

 After the operators have left the house the doors should be closed and 

 tightly sealed and left so for about 12 hours. 



Small fertilizer spreaders such as are used for distributing com- 

 mercial fertilizer on lawns, when properly set, will give a more even 

 and rapid distribution of calcium cyanide, and a higher concentration 

 of gas than can be obtaining by hand scattering. 



Caution: When entering a house after it has been fumigated, 

 use a gas mask until the house has been thoroughly aired out. 



The same precautions are necessary as with sulfur to prevent fumes 

 from reaching and damaging growing mushrooms, although this gas 

 is not so harmful to them as sulfur fumes. In the case of a double 

 house, the other half of which is in bearing, the doors between them 

 should be made gas-tight, all cracks and openings in the partition 

 tightly sealed, and the doors and ventilators of the house in bearing 

 opened. As a further precaution, it is desirable to fumigate when 

 the wind is blowing away from the house in bearing. 



The so-called pot method of fumigation, in which sodium cyanide 

 and sulfuric acid are used, is almost as easy and convenient as that 

 with calcium cyanide, and gives a more rapid liberation of gas and a 

 much higher concentration. The material should be used at the rate 

 of not less than 8 ounces of sodium cyanide to 12 fluid ounces of a 

 good grade (66° Baume) of commercial sulfuric acid and 16 fluid 

 ounces of water per 1,000 cubic feet of air space. Three or four 3- 

 gallon glazed crocks may be used for generators. The necessary quan- 

 tity of water is measured out and divided among these. They are 

 then set at equal intervals in the central alleyway of the house. The 

 acid is similarly measured out and the necessary quantity placed in 

 a glass jar beside each generator. The sodium cyanide having been 

 similarly weighed out (it can be obtained in %-ounce or 1-ounce 

 "eggs'' to save this work), and the proper quantity for each jar hav- 

 ing been put into a heavy brown-paper bag (the thickness of paper 

 may be doubled for additional safety by using two bags, one inside 

 the other, for each charge), the operator takes the twisted necks of 

 the bags in his left hand, enters the house, and pours the acid into 

 each generator as he reaches it. Having reached the back of the 

 house, he then walks rapidly toward the door, dropping one of the 

 bags of cyanide in each generator as he passes it. The acid requires 

 a short time to eat through the paper bags, and the operator is 



