SOME MUSHKOOM DISEASES AND THEIR CARRIERS 7 



bubbles. In houses where these diseases occur mushroom flies have 

 been examined which carried on their somewhat spiny bodies and legs 

 hundreds of spores of these fungi. In addition to these, there are 

 other flies much like them in appearance which feed in the compost 

 and ordinarily do not injure mushrooms. They are, however, able 

 to distribute the spores of these diseases in the same manner as the 

 flies producing the injurious mushroom maggot. All of these flies 

 move actively about through mushroom houses, both by walking and 

 by flight, and are undoubtedly responsible for the rapid increase in 

 the distribution of the diseases in large houses. Diseased mushrooms 

 develop an odor likely to attract some of the larger carrion flies from 

 outside, and these larger flies are capable of carrying much greater 

 numbers of spores throughout the house. On this account particular 

 attention should be paid to the proper screening of the houses. 

 Springtails also are adapted by nature, through their fine, scaly coats 

 of bristles and by their activities on the beds, to further the distribu- 

 tion of these diseases. 



It has been noted that some growers are extremely careless in the 

 disposal of diseased compost. Cases are known to the writers wherein 

 compost cleared from beds in which serious loss from disease has 

 occurred and full of fungous spores was merely piled outside the 

 door of the house during the time the house was being refilled. This 

 permits the carriage of the disease into the house and to the new com- 

 post both by the feet and clothing of the workers and by the myriads 

 of flies leaving this disease-infected material to enter the house each 

 time the door is opened. The house may be thoroughly cleaned and 

 disinfected, but under such circumstances the crop is sure to be a loss 

 through these diseases. 



CONTROL MEASURES 



In the event that either of the diseases described in this circular 

 makes its appearance in a restricted portion of the mushroom house, 

 its spread may be materially delayed by maintaining as great freedom 

 as practicable from both flies and springtails. There is a present 

 tendency toward the use of varieties of mushroom spawn which 

 produce much better crops when maintained at temperatures in 

 excess of 60° F. The increased temperature maintained in com- 

 mercial establishments producing such mushrooms is likely to cause 

 more rapid multiplication and consequently greater abundance of 

 both mushroom flies and springtails and therefore to increase the 

 rapidity of disease distribution. Much can be done, however, to off- 

 set these conditions by applying fumigation or other control methods 

 against these insects so frequently that the adults will be killed 

 practically as they emerge. It is the practice in large commercial 

 greenhouses to apply nicotine or cyanide fumigations for certain 

 insect pests even two to three times a week to attain this result, and a 

 good crop of mushrooms equals in commercial value many of the 

 greenhouse crops protected in this manner. 



NICOTINE 



The fact that nicotine is quite poisonous to flies of this type ren- 

 ders it possibly the most practicable fumigation material. It should 

 be used from medium to heavy strength and either dusted through 



