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



their more or less differing conditions, were added as subjects of study 

 in the practical application of the formaldehyde method for the 

 control of the disease. Experiments were made in fumigating houses 

 with different amounts of formaldehyde, the following proportions 

 being used: 26 fluid ounces of formaldehyde per 1,000 cubic feet, 1 

 quart of formaldehyde per 1,000 cubic feet, and 3 pints of formalde- 

 hyde per 1,000 cubic feet. The proportion of 3 pints to 1,000 cubic 

 feet was found to be more effective and will probably prove the most 

 satisfactory in ordinary practice. In cases in which the leakage was 

 considerable, allowance was made for such loss. 



During the course of the present investigation 16 houses were 

 fumigated by the writer or according to his directions. Two of these 

 houses were fumigated at the rate of 26 ounces of formaldehyde per 

 1,000 cubic feet, five at the rate of 1 quart of formaldehyde per 1,000 

 cubic feet, and nine at the rate of 3 pints of formaldehyde per 1,000 

 cubic feet. 



Two houses which were total failures the season previous to fumiga- 

 tion, after treatment produced crops which the grower reports as 

 follows : " I believe that I never had a finer or more promising house 

 or better mushrooms." The results of fumigation were successful in 

 all cases in which the proper sanitary methods were observed to pre- 

 vent reinfection of the houses. 



From the writer's observations of the results of these experiments 

 with fumigation and the satisfaction expressed by the growers in the 

 course of conversation or correspondence as to the efficacy of the 

 treatment, the important role of formaldehyde as an agent in con- 

 trolling the mushroom disease seems practically demonstrated. 



MEASURES OF CONTROL. 



As a result of the present investigation of the Mycogone disease of 

 mushrooms, the following measures may be advised for the control of 

 the fungus. The treatment is more or less prophylactic in its nature 

 and seeks rather to prevent the appearance or spread of the disease 

 than to eradicate the fungus after it has actually made its appearance. 



Sanitation Necessary in Relation to the Disease. 



Too much emphasis can not be placed upon the danger from the 

 fungus, because of its highly infectious nature. The remarkable 

 rapidity with which the fungus is propagated and the great vitality 

 possessed by the spores, as shown in the preceding pages, make it 

 absolutely essential to observe great care in the construction of new 

 beds or in passing from an infected to a noninfected bed. The ways 

 in which the spores may be carried from place to place are numerous. 

 They may be contained in the manure or soil for the casing of the 

 beds, in particles of earth or manure adhering to the boots and shoes 



