PROPAGATION BY MEANS OF SEEDS AND SPORES 41 



FIG. 22. The sterilizing pan or tray, put face down on a seed-bed. 



stantly wet. Hot sand, sifted over the plants, will check it, 

 but there is no complete remedy. As soon as the trouble 

 appears, give more air and prick out the plants. 



While there may be no remedy for these soil-borne diseases, 

 there is good preventive in the sterilizing of the earth by means 

 of heat. The commonest method is to invert a large flat 

 shallow pan or tray over the seed-bed and then to inject live 

 steam beneath it. This method is employed extensively in 

 raising lettuce and other crops under glass, and also in frames 

 and yards in the open. Following is an account of the process 

 by E. G. Beinhart in Farmers' Bulletin 996, United States 

 Department of Agriculture on 

 "Steam sterilization of seed-beds 

 for tobacco and other crops" (1918), 

 the illustrations (Figs. 21, 22, 23) 

 being adapted : 



"The equipment recommended for 

 steam sterilizing seed-beds under average 

 conditions consists of the following : 



A portable boiler of 20 horse- 

 power or larger capacity. 



Heavy f-inch steam hose, 25 feet. 

 Iron f-inch pipe sufficient in length 

 to carry the steam from the boiler to FlG 23 The nipple connection 

 all parts of the beds. to the steam box. 



