16 



MASS. EXPERIMENT STATION BULLETIN 351 



Table 7. — Effect on Germination when Vinegar Was Applied to Soil 



AFTER Seeding 



Application of Vinegar 

 per Square Foot 



Germination 

 Injured 



Germination 

 Unaffected 



Germination 

 Improved 



237 cc. undiluted Agapanthus Calla 



Antirrhinum maurandioides Lachenalia 



Mentha Requienii 



237 cc. diluted with an Calendula 

 equal volume of water Cabbage 



Pepper 



189 cc. undiluted 



Cabbage 



189 cc. diluted with an Cabbage 

 equal volume of water 



Pepper 

 Pepper 



Opuntia .'■p. 

 O. humifusa 

 O. vulgaris 



Pepper 



Beet 



Tomato 



(after a little delay) 



Calendula 



Beet 



Pepper 



Calendula 



Beet 



Pepper 



In a few cases, soils were watered with diluted vinegar after the emergence 

 of seedlings, and a very little vinegar — too little to prevent damping-of? — was 

 then injurious. Twenty cc. per square foot, diluted with whatever water the soil 

 needed and applied whenever water was needed, was harmful to the growth of 

 Ageratum, Thunbergia, cress, and lettuce; and 50 cc, thus applied, was also 

 injurious to beet, pepper, and tomato. 



Pyroligneous Acid 



This is not a chemical compound, but a mixture of acetic acid and a number 

 of other constituents in water (45). In earlier work (29), the undistilled pyrolig- 

 neous acid (diluted 4:100, 2 quarts per square foot) prevented most damping-ofT 

 and was safe to use one day before seeding. This undistilled acid, except as in- 

 dicated below, had been made by converting hardwoods (birch, beech, and 

 maple) into charcoal and distilling the smoke. It differs from the distilled acid 

 in containing some, or more, wood tar. 



The acids were variously diluted, 4:100 meaning 4 parts of the acid with 96 

 parts of water, and they were, except as indicated below, applied to soil within a 

 few hours before the seeds were sown. 



Undistilled pyroligneous acid was more effective in controlling damping-ofT 

 than was the distilled. Results with each, the means in five experiments, with 

 2 quarts applied per square foot, are recorded in Table 8. Distilled pyroligneous 

 acid, 6:100, reduced the severity of damping-off, but did not satisfactorily control 

 the disease. 



