Vinegar Research Shows It a Weed Killer

May 17, 2002

Agricultural Research Service scientists offer the first scientific evidence that vinegar may be a potent weed killer that is inexpensive and environmentally safe--perfect for organic farmers. ARS researchers Jay Radhakrishnan, John R. Teasdale and Ben Coffman in Beltsville, MD, tested vinegar on major weeds--common lamb's-quarters, giant foxtail, velvetleaf, smooth pigweed and Canada thistle--in greenhouse and field studies.

They hand-sprayed the weeds with various solutions of vinegar, uniformly coating the leaves. The researchers found that 5% and 10% concentrations killed the weeds during their first two weeks of life. Older plants required higher concentrations of vinegar to kill them. At the higher concentrations, vinegar had an 85-100% kill rate at all growth stages. A bottle of household vinegar is about a 5% concentration.

Canada thistle, one of the most tenacious weeds in the world, proved the most susceptible; the 5% concentration had a 100% kill rate of the perennial's top growth. The 20% concentration can do this in about two hours.

Spot spraying of cornfields with 20% vinegar killed 80-100% of weeds without harming the corn, but the scientists stress the need for more research. If the vinegar were sprayed over an entire field, it would cost about $65 per acre. If applied to local weed infestations only, such as may occur in the crop row after cultivation, it may only cost about $20 to $30. The researchers use only vinegar made from fruits or grains, to conform to organic farming standards.