VINEGAR AS AN HERBICIDE
VINEGAR AS AN HERBICIDE
The word vinegar comes from vinegre, coined from two Latin words vinum meaning wineand acer meaning sour. There are a number of historical references about the use of vinegaras a preservative, condiment, beauty aid, cleaning agent and medicine.
Vinegar can be produced naturally by decomposition of plant products under anaerobic conditions.Acetic acid, commonly called ethanoic acid, with a chemical formula CH3COOH, isformed by the fermentation of alcohol. Vinegar of about 5% acetic acid concentration is preparedfrom wine (grapes), cider (apples), or malt (grain). The biological process of vinegar manufactureinvolves conversion of sugars into alcohol and carbon-dioxide through fermentation. By anoxidative process, the alcohol in presence of certain bacteria reacts with air to form vinegar.Concentrated acetic acid as used in industry is prepared by several synthetic processes, such as thereaction of methyl alcohol and carbon monoxide (CO) in the presence of a catalyst, or the oxidationof acetaldehyde or petroleum. This synthetic process is not acceptable for agricultural use by theorganic community. Acetic acid concentration of vinegar derived from plant sources can beincreased from 5 % to 15% via distillation and to 30% via freeze evaporation or other processes.The organic community approves of these processes for agricultural use.
Environmental fate of acetic acid: Acetic acid readily degrades inwater and shows little potential for bioaccumulation. It is biodegradable (MITI Report 1984,Ministry of International Trade and Industry, Tokyo). In an experiment conducted at SwedishAgricultural University it was found that addition of 24 % vinegar to a peat soil decreased the pH ofthe soil from 7.3 to 5.6. However, after 48 hours the pH values of the soil returned to 7.0-7.5.(David Hansson, personal communication)
Vinegar sources that we have used in this projectinclude:An inexpensive, environmentally safe herbicide for spot treatment on organic farms. Control of unwanted vegetation along roadsides and range lands Control of weeds by homeowners around yards, brick walls and patios Weed control in cracks in pavements (It is registered for this use in Sweden, David Hansson,Personal communication)
1. Knouse Foods, Biglersville, PABoth Burns-Philip and Heinz companies supplied white vinegar distilled from grain with acetic acidconcentrations ranging from 5- 30 %. Knouse provided vinegar made from apples atconcentrations up to 14 % acetic acid. There may be other sources of vinegar. However in orderfor vinegar to be allowed in organic agriculture, production must be from a natural source by naturalfermentation methods. Vinegar purchased at the supermarket is 5 % acetic acid.
2. Burns-Philip Food Inc, Baltimore, MD
3. Heinz USA, Pittsburgh, PA
American News Writer
Many people are familiar with the wide variety of uses for vinegar. It's often used as a spice for salads and fine dressings, a disinfectant and even a stain remover in some cases. With so many uses, it should come as no surprise that vinegar is quickly becoming a popular product in the war on weeds. "I started using it three years ago," said Gary Cwach, a farmer in Yankton. "I was having a lot of trouble with Canada thistle, and nothing I tried worked. I finally tried using vinegar, and it worked well. Using it and getting the calcium level in the soil where it belongs have been the key." Cwach said vinegar is not only cheaper than chemical herbicides, it's also a safer and more natural way to get rid of weeds. He buys 55-gallon drums of vinegar for $300 each. Cwach dispenses the vinegar by putting it into a 15-gallon spray tank that he attaches to an all-terrain vehicle. The vinegar, which is fully biodegradeable, is released through a 14-foot-long boom. He said he usually makes two passes over areas in need of spraying. On average, he uses about five gallons of vinegar an acre. "It's been effective for me, and it's something worth taking a look at," Cwach added. Norbert Haverkamp, owner of Natur's Way Inc. in Horton, Kan., said he has been selling vinegar as a weed killer for the last 15 years. He said it has been popular with organic farmers and farmers who have become wary of using chemical sprays. "Too many people are having bad reactions to the chemicals they've used," Haverkamp said. "Because of that, more people are getting interested in safe alternatives. I think you'll see more farms using vinegar as time goes on." Finding information about vinegar is fairly easy to do, according Haverkamp. However, he said there is a lack of hard, scientific facts available about vinegar and its use as a method of weed control. That may change, thanks to a study being conducted by the Agricultural Research Service in Beltsville, Md., the chief scientific research agency of the U.S. Department of Agriculture. ARS researchers Jay Radhakrishnan, John R. Teasdale and Ben Coffman began a scientific study of vinegar as a weed killer about two years ago. The study is credited as being the first of its kind. So far, the researchers have tested vinegar on the most common weeds, including common lamb's quarters, giant foxtail, velvetleaf, smooth pigweed and Canada thistle. The tests have been done in a greenhouse and in the field. The weeds' leaves were sprayed uniformly with various solutions of vinegar made from fruits and grains, and the researchers determined that 5- and 10-percent concentrations killed the weeds during their first two weeks of life. A bottle of household vinegar is about a 5-percent concentration. 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. Canada thistle, which is considered one of the most tenacious weeds in the world, proved to be the most susceptible to vinegar. The 5-percent concentration had a 100-percent kill rate of the perennial's top growth. The 20-percent concentration had the same effect in a two-hour time frame. Spot spraying of cornfields with a 20-percent concentration of vinegar killed 80 to 100 percent of the weeds without harming the corn, but the three scientists said there's still a need for more research. Coffman said studies are currently being done to test vinegar's effectiveness in killing perennials like Canada thistle by soaking the ground containing the weeds. By doing so, Coffman said the weed's root system, which contains a high level of nutrients, can be attacked directly. "One of the positives of using vinegar is that it works on annual plants, and it does so with one application," Coffman said. "With perennials, it takes several applications and you have to get to the root system." Coffman said the study is still in its infancy, but data generated so far has been positive, which is good news to those with weed problems. Among this group are organic farmers, who must adhere to strict guidelines when it comes to killing weeds. "We're still early in the stages of the study, but it is showing a great deal of promise," Coffman said. Lonny Mikkonen of Frederick said his use of vinegar to kill weeds has been limited, and he is eager to see what the ARS' studies conclude. Mikkonen, who has been a certified organic farmer since 1989, said he currently uses methods like tilling and rotation to control weeds. But he does have a large drum filled with vinegar should the need for spraying arise. "I might use (vinegar) for a few problems that I can't solve through tillage and rotation," Mikkonen said. "But for now, I don't have any plans to use it exclusively."
Written by: Dr. Jay Radhakrishnan, Sustainable Agricultural Systems Laboratory
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