CONTROL OF DAM PING-OFF 5 



Table 2. — Relative Number of Plants Which Lived in Soil Treated 

 Immediately After Seeding 



Soil Treatment' 



No treatment (check) 100 100 100 100 100 100 100 100 100 ICO 100 



Formaldehyde 2 cc 133 109 83 135 108 338 295 123 101 341 102 



Acetic acid 2 cc Ill ... 109 106 102 136 116 124 97 214 101 



Seidorin 1 cc 118 163 108 62 95 269 295 135 88 275 101 



Chlorox30cc 91 103 100 90 89 227 101 50 85 145 106 



Copper zeolite2 5.67 gm. .. 113 76 79 109 92 175 106 108 



Vasco3 5.67 gm 110 95 100 97 103 147 106 121 101 89 82 



Cuprocide 544 5.67 gm 106 86 84 91 94 220 164 123 88 93 98 



Semesan 5.67 gm 55 97 44 96 



Bordeaux 1.5:1.5:50 94 98 135 117 118 100 72 92 



'In 0.8 quart of water per square foot. 



^Containing 25 percent copper. 



'A zinc compound for seed treatment, made by Virginia Smelting Co. 



^A red cuprous oxide, product of Rohm and Haas. 



Thus used, it often gave results which were somewhat inferior to those obtained 

 by formaldehyde; but, lacking the latter, acetic acid or vinegar is a good sub- 

 stitute. 



Vinegar as commonly sold contains 4 to 5 percent acetic acid. Damping-off 

 was usually well controlled, and without injury to most plants with which it was 

 used, when vinegar (a little less than one-half pint per square foot) was worked 

 into soil before seeding (4). 



Vinegar, 215 cc. (0.45 pint) in 1 quart water per square foot, completely pre- 

 vented damping-off when applied to soil immediately after seeding. Thus used, 

 it increased by the following percentages the number of plants which lived: beet, 

 427; cucumber, 112; cabbage, 56; lettuce, 24; and pepper, 106. Applied without 

 additional water, this quantity of vinegar interfered with the growth of cabbage 

 but did not affect beet and cucumber. 



When applied from below, by setting pots or flats of soil in the solutions until 

 soil was saturated, vinegar 1.5 quarts in 1 gallon water or acetic acid 1:55 gave 

 good results, although net so gcod as did formaldehyde. 



The soils with which vinegar was used in the experiments referred to above 

 had pH values of about 5.8. In one case, vinegar (215 cc. in 1 quart water per 



Table 3. — Effect of Soil Reaction on Vinegar as a Soil Disinfestant 



Soil Treatments 



Soil pH 

 Values 



Relative Number of 

 Plants Whicii Lived 



Beet 



Cucumber 



Percentages 

 Whicfi Damped-off 



Beet Cucumber 



None (check) 5.8 



Vinegar 5.8 



None (check) 7.1 



Vinegar 7.1 



100 

 435 



100 



137 



100 

 725 



100 



148 





 16 



84 







45 



