By Don Comis
May 15, 2002
Some home gardeners already use vinegar
as a herbicide, and some garden stores sell vinegar pesticides. But no one has
tested it scientifically until now.
Agricultural Research Service
scientists offer the first scientific evidence that it may be a potent
weedkiller that is inexpensive and environmentally safe--perfect for organic
ARS researchers Jay Radhakrishnan, John R. Teasdale and Ben Coffman in
Beltsville, Md., tested vinegar on major weeds--common lambs-quarters,
giant foxtail, velvetleaf, smooth pigweed and Canada thistle--in
greenhouse and field
They hand-sprayed the weeds with various solutions of vinegar, uniformly
coating the leaves. The researchers found that 5- and 10-percent 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- to 100-percent kill rate at all growth stages. A bottle of
household vinegar is about a 5-percent concentration.
Canada thistle, one of the most tenacious weeds in the world, proved the
most susceptible; the 5-percent concentration had a 100-percent kill rate of
the perennials top growth. The 20-percent concentration can do this in
about 2 hours.
Spot spraying of cornfields with 20 percent vinegar killed 80 to 100 percent
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.
ARS is the U.S. Department of
Agricultures chief scientific research agency.