18 BULLETIN 127, U. S. DEPARTMENT OF AGRICULTURE. 



formaldehyde solution, one containing 5 per cent — a gallon to a barrel 

 of water — of one of the sanitary fluids composed of coal-tar deriva- 

 tives will be satisfactory. This percentage is higher than that 

 commercially recommended. 



When the material is removed from the bed at the completion of the 

 production of the crop, it should be immediately removed to places 

 where there will be no possibility of bringing the disease back into the 

 houses. The Mycogone disease, as far as is known, does not affect 

 other cultivated crops. The old compost may therefore be used as a 

 fertilizer, but it should be sold only to farmers who will carry it to a 

 distance and to a locality where mushroom cultivation is not prac- 

 ticed. 



The ground in the vicinity of the houses, the composting yard, and 

 places with which the diseased materials have come in contact must 

 be thoroughly sprayed with one of the disinfectants. If it is necessary 

 to place the new manure or soil on ground where the old compost 

 from diseased houses has rested, it will be necessary to give several 

 such sprayings. 



All tools, carts, wagons, and wheelbarrows which have been used to 

 handle the infected materials must be thoroughly treated with the 

 disinfectant. 



Soil for the casing of the beds and for mixing with the manure must 

 be selected from a place which has not been in contact with the disease. 



The houses which have been fumigated should be kept closed until 

 precautions to prevent the reentrance of the disease have been taken. 



Directions for Fumigating Mushroom Houses. 



Preparatory to fumigation, the houses should be completely cleaned 

 of all old bedding material and thoroughly swept. The proper 

 method for the disposal of this material has already been described. 



A warm, moist day should be selected for fumigation, as the fungi- 

 cidal effect of the gas is greater under such conditions. To this end, 

 the house should be thoroughly sprayed with water and kept warm 

 for about a week or ten days. To insure sufficient humidity, this pro- 

 cess should be repeated the day before the fumigation is to be per- 

 formed. The houses should be closed and sealed and made as nearly 

 air-tight as possible by pasting paper over all cracks and filling up 

 all openings, thus preventing the escape of the gas. If care is not 

 exercised to prevent leakage of the gas, the fumigation may be ren- 

 dered ineffective. The same grade of formaldehyde (or commercial 

 formalin) as that used in the experiments with pure cultures of the 

 fungus is advised for practical work. 



Three pints of formalin should be allowed for every 1,000 cubic 

 feet of space, the reagents being used in the proportion of 1 pint of 

 formalin to one-half pound of potassium permanganate. In houses 



