STEAM STERILIZATION OF SEED BEDS. 15 



confine the fumes. It should then be aired for 8 or 10 days to allow 

 the escape of the fumes from the soil. The seed should not be sown 

 so long as there is a trace of the formaldehyde, for this will kill 

 the germinating seed or young seedlings. 



The use of formaldehyde is recommended only when steam 

 sterilization is not practicable. Its cost is greater than the cost of 

 steaming, and it is usually less effective. 



APPLICATION OF THE STEAMING PROCESS TO CROPS OTHER 

 THAN TOBACCO. 1 



The steaming of greenhouse soils with coils of pipes embedded 

 therein had been practiced for a number of years prior to the de- 

 velopment of the inverted-pan method of steaming as applied to tobac- 

 co seed beds. Since its adoption on tobacco seed beds the inverted-pan 

 method of steaming has been demonstrated to be effective for green- 

 house work, and, further, it is easily seen that the method can be 

 applied to hotbeds and coldframes for various other crops. It is 

 especially valuable in the production of vegetable crops where it is 

 desired to control damping-off and other fungous diseases which 

 may be in the soil. The special requirements for any particular 

 situation will readily suggest themselves, and the apparatus de- 

 scribed for tobacco seed beds can be 'easily modified in size and shape 

 of pan and arrangement of piping to suit almost every condition of 

 soil steaming in greenhouses, outside frames, or even in open fields. 



1 It is upon the suggestion of Dr. W. A. Orton, Pathologist in Charge of Cotton, Truck, 

 and Forage Crop Disease Investigations, that the attention of the truck grower is directed 

 to the application of the inverted-pan method of steaming for the control of certain vege- 

 table diseases. 



