Soil Disinfection 465 



Abundant watering is necessary to prevent root injury of the 

 seedlings. 



Disinfection by copper-sulfate. — This chemical may be 

 used up to one-fourth ounce per square foot. It is employed 

 chiefly for conifer seed beds. 



Disinfection by zinc-chlorid. — Five-eighths of an ounce 

 of this solution per square foot may be employed for conifer 

 seed beds, but it is more expensive than copper-sulfate. 



Disinfection by hot water. ^^^ Pots, flats, etc., may be 

 disinfected by submersion in hot water, 98° C. (208° F.) for 

 five minutes. The quantity of water necessary increases 

 with the volume of soil to be treated ; thus for 8" pots about 

 3000 cc. of water is needed at 98° C. or 2000 cc. of boiling 

 water. On shallow benches boiling water should be used at 

 the rate of 7 gallons per cubic foot of soil. 



