22 



SOME FUNGOUS DISEASES OF ECONOMIC IMPORTANCE. 



Experiment No. 1. 



800 c. c. formalin per 1,000 cubic feet of air space. 

 Temperature before mixing reagents, 72° F. 



Thielaviopsis cultures in petri dishes. 



Initial Vigorous 



growth i growth 



of fungus, of fungus. 



Checks; fungus not exposed to formaldehyde ; 



Fungus exposed 1 5 minutes 



Fungus exposed 30 minutes 



Fungus exposed 60 minutes 



Hours. 

 26 

 49 



Hours. 



50 



73 



115 



165 



The relative retardation in the growth of the checks and the 15, 

 30, and 60 minute transfers one hundred and forty hours after fumi- 

 gation is shown in Plate II. 



Experiment No. 2. 



850 c. c. formalin per 1,000 cubic feet of air space. 

 Temperature before mixing reagents, 72° F. 



Thielaviopsis cultures in petri dishes. 



Initial 



growth 



of fungus. 



Vigorous 



growth 



of fungus. 



Checks; fungus not exposed to formaldehyde gas . 



Fungus exposed 15 minutes 



Fungus exposed 30 minutes 



Fungus exposed 60 minutes 



Hours. Hours. 

 25 50 



65 

 92 



144 



113 

 143 

 61 



Experiment No. 3. 



900 c. c. formalin per 1,000 cubic feet of air space. 

 Temperature before mixing reagents, 72° F. 



Thielaviopsis cultures in petri dishes. 



Initial 

 growth 

 of fungus. 



Vigorous 



growth 



of fungus. 



Checks; fungus not exposed to formaldehyde gas. 



Fungus exposed 15 minutes 



Fungus exposed 30 minutes 



Fungus exposed 60 minutes 



Hours. 

 24 



124 

 168 



Hours. 

 49 

 134 

 168 



Plate III shows the relative retardation in the growth of the cul- 



tures due to the use of the gas. 



Experiment No. 4- 



950 c. c. formalin per 1,000 cubic feet of air space. 

 Temperature before mixing reagents, 72° F. 



Thielaviopsis cultures in petri dishes. 



Initial 



growth 



of fungus. 



Vigorous 



growth 



of fungus. 



Checks; fungus not exposed to formaldehyde gas 



Hours. 



22 



116 











Hours. 

 49 



Fungus exposed 15 minutes 



210 



Fungus exposed 30 minutes 







Fungus exposed 60 minutes 











171 



