Vinigar

[Carolyn LeCrone]

A neighbor uses vinegar to kill weeds growing in cracks in the street and sidewalk. Does the vinegar degrade? Are there long term negative affects? Carolyn

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From everyth>A neighbor uses vinegar to kill weeds growing in cracks in the street and

[paghat]

The acetic acid in vinegar is highly caustic & commonly recommended as an organic herbicide. It is also used to acidify overly alkaline soil, though such chemical tinkering with the soil has a bad accumulative effect & it is better to acidify soil with compost or peat.

Acetic acid is non-selective & kills everything. At solutions rich enough to kill plants it will also acidify the soil far more than is good for plants or healthful microorganisms. Kitchen vinegar is 5% acetic acid which is very mild (acetic acid can kill even people but obviously at such dilute strengths it is a safe part of the average family diet). 5% solutions might not be strong enough for the toughest sorts of mature weeds though its adequate for seedling weeds & anything sensitive. A 20% acetic acid solution would kill everything within two hours of contact, but could also be harmful to skin contact; I wouldn't recommend looking for a stronger source than kitchen vinegar, but there are horticultural grades of acetic acid that are even stronger than necessary, 25% acetic acid, which could really do a number on your lawn if you're sick of all that greenery.

I wouldn't ordinarily use it since it is harmful to everything it touches, but cracks in the street or sidewalk might be a reasonable exception. I really prefer manual removal of weeds & topcoating with composted manure which suppresses germination of weeds' seeds while benifiting all the wanted plants, but if a herbicide were REALLY necessary, I'd consider vinegar.

The USDA's Agricultural Research Service (ARS) did the first field & greenhouse analyses of vinegar as an organic herbicide specifically so that organic farmers would know for certain it had no negative effect on crops. Spot-treatment in cornfields, one weed at a time, was effective in eradicating the majority of all the most aggressive weeds, with no ill effeccts to the corn so long as the corn was not also sprayed. It was found useful for pre- & post-crop weed suppressant to stop new weeds from emerging. But there is always danger to plants because it just as rapidly injures desirable plants & can only be sprayed on absolutely windless days in circumstances that do not risk accidentally killing everything else in addition to the weeds.

Here's an article on the topic:

here's the Agricuoltural Research Service press release: University did follow-up studies to the USDA research, the major findings noted here: the ratgirl

[Phisherman]

Household vinegar contains acetic acid which breaks down over time. It is a weak acid. I probably would not regularly use an acid (weak or strong) on concrete as this could weaken it and cause spaulding. My choice is a propane torch or RoundUp--both are kind to concrete and the environment.

[dps]

The propane torch is effective against broadleafed weeds, but not grasses. The growing point of grasses is located below ground, so the flame doesn't affect it. Excessive heat against concrete or asphalt could damage it.

Note that it is not necessary to char the plant, only to heat up the leaves enough to boil the liquid inside. This ruptures the cell wall and the plant dies. When you apply the flame, the leaves take on a brief shiny appearance due to the fluids coming out of the surface. It may not look as if it has died for a few minutes, but be patient. If the plant is more than 2" high, it may take several heat treatments to fully kill it. Trying to reduce the plant to charcoal is a waste of fuel and time (although in the case of really tough plants it may be psychologically satisfying).

I tried household vinegar a few years ago on broadleafed weeds on a gravel parking lot. It killed the grasses and broadleaved weeds, but two weeks later they were there again. The propane torch worked better.

[J. Del Col]

Strong acetic acid solutions produce very nasty fumes in addition to causing chemical burns to the skin and eyes. They must be handled with care. Long rubber gloves and splash-proof goggles are a must.

Anybody who formulates stop baths for photography knows what it is like to work with 28% acetic acid or glacial (essentially pure) acetic acid---you definitely don't do the mixing in a closed space.

J. Del Col

[dr-solo]

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List Manager: Puregold Goldfish List

the problem, dont waste energy finding who's to blame ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Unfortunately, I receive no money, gifts, discounts or other compensation for all the damn work I do, nor for any of the endorsements or recommendations I make.

[J. Del Col]

ALL acetic acid is exactly the same stuff, regardless of origin.

J. Del Col

[dykes on bikes]

You have to realize that Ingrid is a liberal, and therefore thinks there is something magical about anything that is "organic".

[Phisherman]

Not exactly, but for most practical purposes they are the same chemical. One exception is stereo activity (chemicals extracted from plant material are stereo active.) I realize "Organic" has little to do with "Organic Chemistry."

[dr-solo]

actually............

acetic acid is not a fermentation product. " Most acetic acid made for industrial use is made by one of three chemical processes: butane oxidation, acetaldehyde oxidation, or methanol carbonylation."

it doesnt matter cause once the glacial is diluted bacteria can still break it down. Ingrid

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List Manager: Puregold Goldfish List

the problem, dont waste energy finding who's to blame ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Unfortunately, I receive no money, gifts, discounts or other compensation for all the damn work I do, nor for any of the endorsements or recommendations I make.

[Sib Hashian's Afro]

Tell your neighbor to boil some water in a tea kettle, then carefully pour the scalding hot water onto the weeds. I've been doing this for years and it does the job nicely.

[N. Thornton]

thats what I thought until I got one. Hopeless thing, I havent botherd with a new gas canister.

NT