Acetic acid has been recently investigated for its potential as an herbicide. When applied, acetic acid solutions have been found to act as a non-selective contact herbicide. Concentrations of 10, 15 or 20% acetic acid have been shown to be effective against many weeds, especially small annuals. The 5% concentration (supermarket vinegar is 5 % acetic acid) has provided inconsistent levels of weed control. To be permitted for use in organic systems, the acetic acid must be produced and concentrated by approved methods.
Acetic acid is naturally derived from the fermentation of plant products under anaerobic conditions. Commonly, apple cider, wine, and malt are fermented to produce a 5% acetic acid solution also known as vinegar. This acetic acid can be concentrated from 5 % to 15% by distillation and to 30% by freeze evaporation. These processes are permitted under organic standards.
* Acetic acid can also be prepared by several synthetic processes, such as the reaction of methyl alcohol and carbon monoxide in the presence of a catalyst, or the oxidation of acetaldehyde or petroleum. These methods are not permitted for use in organic systems. In addition, some acetic acid herbicides may contain prohibited wetting agents.
Acetic acid readily degrades in water and shows little potential for bioaccumulation. It is also biodegradable. The application of acetic acid to soil has been shown to lower pH temporarily; however, pH returns to normal in 48 hours. |
