Acetic Acid as a Soil Disinfectant '

Acetic acid, in vinegar, is one of the most anciently used preservatives. Its toxicity to bacteria and to fungi has been recognized. Wolf and Shunk (^6) ^ found that it was more toxic to the six species of bacteria investigated by them than was hydrochloric, sulphuric, citric, tartaric, malic^ or formic acids. In the experiments of Bitting (4) acetic acid was as toxic to fungi as benzoic, boric, or salicylic acids, and it killed Pénicillium exjpansum, Alternaria solanij and Oidium lactis under conditions in which citric, lactic, malic, and tartaric acids only slightly retarded their growth. According to Rideal and Rideal (20), acetic acid 0.3 per cent kills Bacillus typJiosus, Uppal (24) found that it was toxic to the conidia of Phytophthora colocasiae. Wüthrich (27) reported that 0.01 N acetic acid prevented the germination of the conidia of PhytopJithora infestans and Plasmopara vitícola and the spores of Ustílago carbo. Results secured by Piemeisel (16) led him to believe that it is acetic acid which kills the spores of Ustílago zeae in silage. Acetic acid, 0.1 per cent, was found by Hitchcock and Carleton (11) to prevent the germination of urediniospores of Puccinia coronata. Acetic acid may have a toxic or a stimulatory effect on higher plants. In the experiments of Lövinson (14) it retarded the germination of peas. Carr and Havercamp (6) found that the weights of plants decreased as the quantity of acetic acid, added to the soil in which they were growing, was increased. Heald (10) found that the growth of corn seedlings was prevented by a certain concentration of acetic acid, but that this concentration was greater than the concentration of hydrochloric or sulphuric acids which is toxic to these plants. In the experiments of Small (21) a much larger percentage of cuttings of rose, privet, and veronica rooted in acetic acid, 0.01 per cent, than in water, and root systems became larger in the acid medium. Promsy (17, 18) found that the germination of seeds was hastened and the growth of seedlings increased by the application of acetic acid to the sand in which they were growing. The toxicity of acetic acid has been considered or explained by True (23), Kahlenberg and True (13), Heald (10), Winslow and Lochridge (25), Reichel (19), Dunn (8), Cohen and Clark (7), and Uppal (24)' Apparently, the toxicity of acetic acid is due partly to the hydrogen ion and largely to the undissociated molecule. Kahlenberg and True (13) found that undissociated acetic acid is toxic> and, according to Heald (10) and True (23), the C2H3O2 ions are not