14 BULLETIN 127, U. S. DEPAETMENT OF AGRICULTURE. 



the check cultures were constant and characteristic of this series of 

 experiments. 



Treatment with Coal Oil. 



Early in the investigation of the problem of this mushroom disease 

 it was learned that certain growers believed coal oil to be effective in 

 destroying the spores of the fungus and checking the spread of the 

 disease. The coal oil was poured on sections in the beds where 

 diseased mushrooms had appeared and was also employed for the 

 disinfection of the hands and tools. In order to demonstrate the 

 efficacy or inefficacy of this treatment a large number of cultures of 

 the fungus were grown on corn meal in 100-cubic-centimeter flasks 

 and subjected to the direct action of the oil. These cultures were of 

 various ages, but all in a state of vigorous growth. An arrangement 

 was made by which the flasks could be inverted over the nozzle of a 

 pipe supplying compressed air and made to pass through a stream of 

 coal oil. The compressed air was turned on and the coal oil sprayed 

 upon the culture. One half of the cultures were removed after the 

 fungus had become covered with a film of coal oil. It was thought 

 that this would be comparable to the condition in a mushroom 

 house where coal oil was sprayed on the bed boards, walls, floors, 

 and ceiling. The remaining cultures were sprayed until they were 

 drenched with oil. In these the coal oil thoroughly penetrated the 

 culture, which was practically an immersion of the fungus in coal oil. 



As in the experiments with formaldehyde, transfers were im- 

 mediately made from the treated cultures. These cultures grew as 

 quickly and as vigorously as the check cultures (transfers made 

 from the cultures before being treated with coal oil). A sufficient 

 number of these experiments were made to demonstrate the inefficacy 

 of coal oil as an agent for controlling this disease. 



Treatment with Additional Disinfectants. 



Costantin and Dufour (1893a) experimented with a variety of 

 chemicals, to note their action on the growth of the fungus in cultures. 

 The experiments were carried on in such a way that the toxic effect 

 of the chemicals could be definitely determined. The following were 

 used: Lysol, thymol (or thymic acid), boric acid, copper sulphate, 

 calcium bisulphite, and milk of lime. These authors range the 

 chemicals in the order of their effectiveness as follows: (1) Lysol 

 (2 per cent solution), (2) thymol (2 per cent solution), (3) copper 

 sulphate (2.5 per cent solution), (4) boric acid (to saturation). The 

 milk of lime which many growers used for cleaning their caves was 

 ineffective in preventing the growth of the disease, and the use of 

 calcium bisulphite is not advised. From these experiments these 

 authors advise the use of a 2 or 2.5 per cent solution of lysol as a 

 spray to disinfect mushroom caves. 



