CONTROL OF DAM PING-OFF 



15 



Table 13. — Results with Different Concentrations of Formaldehyde, 

 THE Rate of Application per Square Foot of Soil Being Undetermined 



Treatment 



Relative Number of Plants Which Lived 

 Beet Cabbage Cress Cucumber Pepper Tomato 



Check (water only) 100 



Formaldehyde — teaspoonfuls in 

 each gallon of water 



1.0 275 



1.5 332 



2.0 288 



100 



100 



100 



100 



100 



Thus used, the concentration of formaldehyde known but the rate of applica- 

 tion (immediately after seeding) not accurately' determined, 0.5 teaspoonful in 

 1 gallon water did not give complete protection against damping-off but 1 tea- 

 spoonful did, and the latter improved the stands (see Table 13) as much as did 

 greater concentrations. Crucifers were injured by 1.5 teaspoontuls formaldehyde 

 per gallon, but 2 teaspoonfuls did not injure beet, cucumber, pepper, and tomato. 



When a solution containing 1 teaspoonful tormaldehyde in each gallon of water 

 is applied to soil at the rate of 1 quart per square foot, each square foot receives 

 1.2 cc. formaldehyde. This is probably safe with all vegetables, unless it be the 

 crucifers; but some of the non-crucifers will stand, and may well receive, som.e- 

 what heavier applications. Up to 2 quarts of the solution (2.4 cc. tormaldehyde) 

 per square foot did no harm to beet, cucumber, pepper, and tomato. 



With the object of determining the lightest applications of formaldehyde which 

 are or may be effective against damping-off when applied to soil immediately 

 after seeding, it was so used in the quantities named in Table 14. 



Table 14. — Results of Soil Treatments with Formaldehyde in Light 



Applications 



There was no control by formaldehyde, 0.2 cc. per square foot, but there was 

 fair control by 0.4 cc, good control by 0.6 cc, and very good control by 1.2 cc. 

 per square foot, the last named giving quite as good results as did heavier applica- 



