CHAPTER IV 



METHODS OF TREATING SICK SOILS 



^Damping off, whether induced by Pythium, Rhi- 

 zoctonia, or any ther parasitic organism, is usually 

 confined to seedlings in the seed bed, under cover or 

 in the open. The loss of seedlings not only means a 

 waste of seeds, but it also results in late crops. 

 Growers are usually in the habit of using the same 

 soil in the seed bed, year in and year out. This prac- 

 tice cannot be encouraged, since contamination of 

 the seed-bed soil is bound to take place. The dis- 

 ease-producing organisms are usually brought in 

 with the manure. A number of truckers make it a 

 practice to empty their beds and fill them with fresh 

 soil. This, unfortunately, is not always a safe 

 method, for the reason that the new soil too may 

 be contaminated, or that it may become infected 

 as soon as it is placed in the bed previously con- 

 taminated. Sick seed-bed soils may be freed from 

 damping off in various ways. 



Formaldehyde. When steam sterilization is not 

 feasible because of the absence of a steam boiler, the 

 formaldehyde treatment is the next best. With this 

 treatment we may control Fusarium, Rhizoctonia, 



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