622 



Journal of Agricultural Research 



Vol. X. No. 12 



Table V. — Effect of washing the hands thoroughly with soap and water to remove the 

 mosaic-disease virus. Inoculations made on January 31, igi6, with series of 10 young 

 Connecticut Broadleaf tobacco plants 



SOIL STERILIZATION IN THE SEED BED AND THE OCCURRENCE OF 



THE MOSAIC DISEASE 



In the field the mosaic disease may make its appearance regardless 

 of the type of soil or previous crop conditions. So far as soil infection 

 is concerned, there seems to be no direct relation to previous outbreaks 

 of the disease, either in the seed bed or in the field. As a matter of fact, 

 thorough sterilization of the seed bed with steam does not necessarily 

 control the occurrence of the disease in the field, as experiments carried 

 out at Arlington, Va., in 1915, have shown. Mr. E. G. Beinhart. of the 

 Office of Tobacco Investigations, contributes the following data relative 

 to this sterilization: 



A bed was newly made on a clay soil. Over the clay a mixttu-e of sand, peat, 

 and compost was laid to a depth of 8 inches, and the fertilizers were worked in before 

 steaming was begun. Steam was furnished by a road roller which gave an average 

 pressure of 100 pounds, the range being from 80 to 125 pounds. 



