170 "Damping off," etc., of Tomato Seedlings 



seedlings were removed and the remainder were sprayed with different 

 fungicides or treated as indicated in Table X. The only treatments that 

 resulted in an appreciable reduction of the disease were those of copper 

 sulphate with lime, and formaldehyde with ammonia. Ten parts of dry 

 powdered lime obtained from freshly slaked lime, and one part of copper 

 sulphate were ground to a fine powder and thoroughly mixed. After 

 passing through a fine sieve the mixture was sprinkled thinly over the 

 soil. By this treatment only 7 per cent, of diseased seedlings resulted. 



When formaldehyde and ammonia are mixed an impure solution of 

 hexamethylene tetramine is produced. In the tests, commercial formalin 

 (containing 40 per cent, formaldehyde) was added to a strong solution 

 of ammonia, -880, in the correct proportions to produce a 40 per cent, 

 solution of hexamethylene tetramine. This was diluted to various con- 

 centrations, and 400 c.c. watered on the boxes. The most suitable 

 strength to use proved to be a 0-5 per cent, solution. By its application 

 the percentage of diseased seedlings was reduced to 11. Experiments 

 with older plants "potted up" in diseased soil showed similar results. 



