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.
United States Department of Agriculture scientists offer the first
scientific evidence that vinegar may be a potent weed killer that is
inexpensive and environmentally safe – perfect for organic farmers.
Researchers Jay Radhakrishnan, John Teasdale and Ben Coffman in
Beltsville, Maryland, tested vinegar on major weeds – common lamb’s
quarters, giant foxtail, velvetleaf, smooth pigweed and Canada thistle
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– in greenhouse and field studies.
They hand sprayed the weeds with various solutions of vinegar,
uniformly coating the leaves.
The researchers found that five 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 five percent concentration.
Canada thistle proved the most susceptible. The five percent
concentration had a 100 percent kill rate of the perennial’s top
growth. The 20 percent concentration can do this in about two 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.
Spraying vinegar over an entire field would be expensive.
But the cost could be reduced by 50 percent or more if vinegar is
applied only to local weed infestations, such as may occur in the crop
row after cultivation.
The researchers used only vinegar made from fruit or grain to conform
to organic farming standards.
