First of all, there plenty of stores still selling strong vinegar for herbicide use. I had thought that 2 states had banned vinegar as a hercide but it seems that hasn't happened yet. There are those pushing for it - you can imagine who.
I don't recommend anything but 10% alcohol-based vinegar for herbicide use. 5-8% is too weak, 20% is to strong and many of the 20% products are made from 99% glacial acetic acid (a petroleum-based product). Adding 1 oz. of orange oil and 1 teaspoon of liquid soap to a gallon of 10% vinegar makes a terrific contact herbicide.
For more details of what up in this vinegar debate from Clemson Uiversity:
Whatâ€™s Cooking with Vinegar Recommendations?
Acetic Acid as Herbicide
Dr. Catherine H. Daniels, Pesticide Coordinator, WSU
In May 2002, U.S. Department of Agricultureâ€™s Agricultural Research Service (USDA-ARS) issued a press release describing their research on weed control using vinegar. The research was prompted by the organic farming community's need for an inexpensive and environmentally benign weed killer. Greenhouse and field studies indicated that while 5% vinegar solutions did not produce reliable weed control, solutions of 10, 15, and 20% provided 80-100% control of certain annual weeds (foxtail, lambsquarters, pigweed, and velvetleaf). Perennial weeds (Canada thistle) treated with 5% vinegar showed 100% shoot burndown but roots were not affected, therefore shoots always re-grew. Study details can be found at http://www.barc.usda.gov/anri/sasl/vinegar.html
. The press release noted the potential use of vinegar as an ideal sidewalk crack and crevice treatment. Homeowners around the Pacific Northwest had already heard about purported vinegar uses for killing blackberries in a June 6, 2001, Seattle Post Intelligencer article and had deluged Cooperative Extension offices and Master Gardeners for more information. (See also "Acetic Acid: Miracle Herbicide? Sour Product Promises Sweet Results," AENews Issue No. 185, September 2001). There is something appealing about the idea of a commonly available, inexpensive material such as household vinegar being effective against weeds. It does not harm people, in fact people consume it every day, yet it is deadly to our mortal enemies: lawn weeds. Why, such is the stuff of dreams in the pesticide issues arena!
From Dreams to Reality
Well, I hate to be one who breaks the bad news, but weâ€™re not talking about household vinegar here. The typical strength of the stuff we toss with olive oil or run through the cleaning cycle on our coffee makers is 5% acetic acid, a concentration shown to be less-than-reliable by the ARS study. Beyond that sad fact, responsible stewardship requires that those of us in the business of making pesticide recommendations ask certain questions before embracing a pest control technology. The first of those questions should be, â€œWhat products containing this ingredient are registered for use?â€
Five herbicide products are currently registered in Washington State that contain acetic acid. Two of them come as 25% concentrates with instructions to dilute down to 6.25% and use on rights-of-ways, non-crop, and industrial lands (St. Gabriel Labs Burn Out Weed and Grass Killer Concentrate, Nature's Glory Weed and Grass Killer Concentrate). While these may be useful to commercial applicators, they are not labeled for home uses. Three products are labeled for homeowner use (St. Gabriel Labsâ€™ Fast Acting Burn Out RTU, Nature's Glory Weed and Grass Killer RTU, Greenergy's Blackberry and Brush Block). Their acetic acid concentrations are 6.25%, 6.25%, and 7% respectively. Curiously, Greenergy's product label lists acetic acid as an inert ingredient; citric acid is listed as the active ingredient. By listing the ingredients this way, Greenergy is able to take advantage of EPA's "Minimum Risk Pesticide" definition. Products falling under this category are also known as â€œ25(b) productsâ€ after the FIFRA rule describing criteria for minimum risk pesticides. Such products need not be registered at the Federal level and do not carry an EPA registration number. However, Washington law requires that 25(b) products go through the Washington State Department of Agriculture's (WSDA) registration process regardless. Oregon law allows the Oregon Department of Agriculture (ODA) to follow EPA's lead on 25(b)s, so Greenergy does not have to register Blackberry and Brush Block in Oregon. Fast Acting Burn Out RTU is not registered in Oregon, leaving Nature's Glory Weed and Grass Killer RTU and Blackberry and Brush Block legal for use in Oregon.
Down to Earth With a Thump
Another question we must pose if we are to make responsible pesticide recommendations is whether the active ingredient in question works under environmental conditions found in our region. Preliminary field tests in Washington State using 7% vinegar solutions showed results similar to the ARS study at 5%, namely lack of reliable weed control. While extension personnel in Washington and Oregon are able to legally recommend any of the homeowner-registered products listed above (three in Washington, two in Oregon), the data demonstrates erratic weed control. In other words, people should be told that if they want to use vinegar at the registered concentrations it might not work in their situation.
Turning Up the Juice
A few weeks ago a product called Bradfield Horticultural Vinegar (20% acetic acid), sold by Bradfield Industries, was found in a Washington home and garden center. At first glance it seemed the answer consumers had been clamoring for. Upon closer examination however, the product is not registered with EPA and does not qualify under the Minimum Risk Pesticide category for non-registration. The Colorado Department of Agriculture went so far as to issue a media release, warning consumers about the unregistered product (http://www.ag.state.co.us/commissioner/ ... negar.html
.) Apparently the company is trying to take advantage of a gray area of the legal system. There is a part of federal law which states that if a product clearly has uses other than as a pesticide AND the company makes no claims about that product having pesticidal uses, it does not have to be registered as a pesticide. This law makes sense for things like citric acid, culinary herbs and their oils, and other products that are used in a wide range of applications besides pesticides. Acetic acid has numerous other uses so it, too, falls under this category.
Bradfield Industries tried to market their product in Oregon with herbicide uses listed on the label. Oregon Department of Agriculture inspectors contacted Bradfield and told them that if they made pesticide claims on their label, it would have to be registered as a pesticide in Oregon. The company subsequently changed their label. The Bradfield jugs found at the Washington home and garden center bore a plain label stating the productâ€™s name and acetic acid percentage only. But hereâ€™s the kicker: attached to the jug handles by a twist-tie were information sheets discussing some of the common uses for acetic acid: cleaning farm equipment, lowering pH in fertigation and other foliar sprays, AND AS A HERBICIDE! These attached sheets also state that "since vinegar is on the EPA Generally Recognized as Safe (GRAS) List, registration is unnecessary." That statement is misleading and only partially true. Acetic acid is on the list of GRAS inerts, but it is not on the GRAS active ingredient list (remember our earlier explanation of the Greenergy product?)
When we put a call into the Colorado Department of Agriculture to ask them about their concerns, we were referred to Judith Sturgess, EPA Region VII, who is handling an EPA action against Bradfield Industries. This action involves a stop sale order as well as a civil complaint with a financial penalty. EPA's position, according to Ms. Sturgess, is that the vinegar product is illegal as it is not registered as a pesticide, is not in the registration queue, and is not eligible for Minimum Risk status, yet is being distributed with information describing a pesticide use. EPA bases their position on information sheets found with the product and also on information from the Bradfield Web site at http://www.bradfieldind.com/
, which continues to describe the product as a herbicide.
In A Pickle
Letâ€™s see where this series of events has brought us. USDA-ARS has done research to show that 20% concentrations of acetic acid work to control weeds. Many people are clamoring for access to products with these high concentrations, yet no company seems willing to go through the EPA registration process with a 20% product. Adding to the problem, it seems that some USDA personnel are locating sources of 20% product (distributors who sell 20% vinegar to food outlets) and recommending them to the public as sources of herbicide. We have received e-mails to this effect and have followed Web threads evidencing such recommendations.
Can those of us in extension take the same short cut and recommend the higher (unregistered) concentrations, or in fact give people lists of distributors? The answer, at least in Washington State, is NO. There is a legal fine point buried in here. If any material claims to kill pests (weeds) it becomes a pesticide, no matter who does the â€œclaiming.â€ We cannot make a recommendation for an unregistered pesticide. Okay, so what if the material does not claim to be a â€œpesticide,â€ it is simply a â€œfood grade 20% solutionâ€ (normally) sold to those who make pickles? Can we recommend it then? The answer is again, NO. As Ms. Sturgess pointed out, making lists of 20% vinegar outlets is tantamount to directing people to use an unregistered pesticide.
Some may ask what is the big deal over such picky paperwork details when people are clamoring to use the product? After all, isn't the catchphrase of the marketplace "Let the buyer beware"? Besides being legally culpable in recommending unregistered pesticides, we have practical safety concerns for homeowners. Homeowners are not trained in safe handling and storage of concentrated chemicals. Acetic acid concentrations over 11% can cause burns upon skin contact. Eye contact can result in severe burns and permanent corneal injury. The 25% acetic acid concentrations registered through EPA and the states for commercial use all have restricted entry intervals of 48 hours and list personal protection equipment to be used by the applicator. None of this safety information is included on the twist-tie information on the jug of Bradfield Horticultural Vinegar. Because the public is used to thinking of vinegar as something you can safely splash on your salad and eat they are generally unaware of potential dangers of a higher concentration.
Concentrating on Solutions
The simple solution seems to be for a company to step forward and register the 20% concentration as a herbicide. Judging from the reactions on Web threads and from our own experience after publication of newspaper articles, there is certainly enough demand out there to make it profitable. Research, courtesy of USDA, has already been done. Extension stands ready to recommend registered products. So who will step up to the plate?
Dr. Catherine Daniels is Pesticide Coordinator for WSU and the Director of the Washington State Pest Management Resource Service, http://wsprs.wsu.edu.She
can be reached at (509) 372-7495 or firstname.lastname@example.org
. Information presented in this article is condensed into a two-page fact sheet targeted at county agents available at http://wsprs.wsu.edu/VinegarFactSheet.pdf