Presoak Method of Seed Treatment: a Means of Preventing Seed Injury Due to Chemical Disinfectants and of Increasing Germicidal Efficiency

The widespread use of formalin, copper sulphate, and other germicides in seed treatment for the control of seed-transmitted diseases is generally attended by decreased and retarded seed germination. Pathogens on the seed coats, present as dry bacteria, fungus spores, or dormant mycelium, are usually in a resting stage and as such require the use of disinfectants in a fairly strong concentration—i to 80 for copper sulphate (CuS04) and 1 to 200 or 1 to 320 for formalin (CH20)—which often act very detrimentally on the germinating seed. Even much weaker solutions—1 to 200 for copper sulphate and 1 to 400 for formalin—exhibit retarding and killing effects when used on wheat. The use of lime after copper sulphate, while beneficial to some extent, does not entirely prevent seed injury, nor has the detrimental effect of formalin been so far fully counteracted. The economic importance of the annual loss of grain due to seed treatment is such that during the recent war it occasioned an elaborate series of tests of standard grain disinfectants by the War Emergency Board of the American Phytopathological Society. In fact (s)—