Methods of Treating Sick Soils 57 



Table 8, Johnson 1 presents some interesting data on 

 the effect of thick sowing on damping off. 



Table 8 

 Effect of Thick Sowing on Percentage of Diseased Plants. 



Certain soils are especially favorable to damping 

 off. Soils which contain a high percentage of un- 

 rotted vegetable matter and those which are hard to 

 drain need especial attention. Great care should be 

 taken that the seed bed is kept at the right tempera- 

 ture. The latter cannot be guessed at by personal 

 sensation. It should be accurately determined by 

 thermometers placed in the bed at suitable distances. 

 It should also be remembered that any covering cloth 

 or sash will exclude light and air. Every precaution 



Johnson, James, Wisconsin Agr. Expt. Sta. Research Bui. 31: 

 31-61, 1914. 



