I know acetic acid is used as an organic herbicide but how does it actually work?

Question

I know acetic acid is used as an organic herbicide but how does it actually work?

Answer 1

it eats away at your skin

Answer 2

When used as an herbicide it is often a 10% or 20% concentration to be effective on mature weeds. Food uses are at ~5%.

The acid in vinegar injures the plants probably in two ways. The acid injures the plant's outer cuticle and cellular membranes causing rapid water loss. Then it will acidify the surrounding soil somewhat limiting the plant's access to food from the soil. Vinegar is a weak acid so the effect is brief lasting until the next rain. However while still present the low pH of the vinegar will disturb the ability of the plant roots to draw up nutrients and the minor minerals needed to survive if not killed by spraying directly.

If you are interested in greater details the plant has a wax based cuticle that keeps it from losing water.  The amount and types of wax present on the cuticle vary with leaf position on the plant and environmental conditions the plant lives in. New seedlings and growing tips have a  thinner layer. Plants growing in moister climates also develop their cuticle slower than those in harsh dry climates so remain susceptible to vinegar stripping the wax longer. Vinegar is not absorbed into the plant's xylem so it burns only foliage it contacts. Some plants regrow from roots so must be retreated.

http://www.weeds.iastate.edu/mgmt/2001/a...

Vinegar should be applied on warm-hot dry days with no chance of rain and works best on young plants or tender new growth. Even with a 5% solution you don't want to breath it in and definitely it is harmful to lungs at the 20-30% herbicidal concentrations.

Vinegar as an Organic Weed Killer

http://www.moscowfood.coop/archive/Vineg...

Vinegar may also be combined with clove oil or another essential oil as a defoliant or a C9 fatty acid (basically a strong soap) called pelargonic acid. These agent combine to chemically 'burn' the foliage more than just vinegar. Vinegar disrupts the cuticle allowing the other agents access.

http://www.naturesavenger.com/herbicided...

http://wssa.allenpress.com/perlserv/?req...

http://www.bioone.org/perlserv/?request=...