Various lawn and garden stores may carry these products. Like any herbicide, it is important to follow all directions and safety procedures. The USDA issued a warning in their research report stating; “WARNING: Note that vinegar with acetic acid concentrations greater than 5% may be hazardous and should be handled with appropriate precautions”. However, acetic acid is not reported to accumulate in the environment and readily breaks down to water. Interestingly, 24% acetic acid apparently can temporarily decrease soil pH.
Acetic acid is not a selective herbicide. Dr. John Teasdale suggested the mechanism of action of acetic acid is similar to that of paraquat in that acetic acid causes the rapid dissolution of cell membrane integrity resulting in the dessication of foliar tissues, and ultimately plant death. Acetic acid is non-selective, and may damage any plant part contacted by the material.
While acetic acid may burn off the tops of Canada thistle and other perennials, it will not control the root system responsible for regeneration of plants. Furthermore, acetic acid may not control larger weeds
. A recent demonstration at the Nashua Research Farm suggested that acetic acid is not effective at controlling larger weeds
Directed applications (keeping the vinegar away from the crop plant) are necessary to use acetic acid when crops are present in fields. Acetic acid concentrations from 10 to 20% controlled 80 to 100% of the smaller weeds, as reported in the USDA release. Typical concentrations of acetic acid in most commercially available vinegars are 5%, and were reported to provided variable control of small weeds.