Homemade weed killers are all the rage and vinegar or salt or a combination of the two are highly publicized. How well do they work? How do they compare with Roundup? In today’s post I will compare the three options by testing them on real weeds in my garden.
Vinegar, Homemade Weed Killer
I’ve discussed vinegar before in Vinegar Weed Killer Myth. It is effective against small weed seedlings, and it does destroy the green leaves above ground. It has very little effect on roots.
In this post vinegar refers to the stuff you can buy in a grocery store. It does not include 20% acetic acid which is a dangerous chemical that does kill some weeds.
Salt, Homemade Weed Killer
Salt, usually in the form of sodium chloride, the table salt, is recommended quite a bit for killing weeds. It can be used in water, as a solid or even mixed with vinegar.
Salt does kill weeds, as well as all other plants. Sodium is a toxic metal ion which dissolves easily in water. It moves through soil along with the water. If the amount of sodium is high enough it kills plants, so it should be no surprise that it kills weeds.
Unlike synthetic or organic pesticides which break down over time, the sodium ion does not break down. It might be washed away by water to another location, like the soil where you grow favorite plants, or into local rivers and lakes, but it will always be somewhere.
Someone on a social network group said they kill weeds by applying salt, and nothing grows in the spot for at least 2 years. Great – the weeds are gone because the soil has been contaminated so much nothing will grow there until water leeches the excess sodium away. That does not sound like good gardening to me.
Roundup Weed Killer
The active ingredient in Roundup is a chemical called glyphosate. Contrary to popular belief, this is a safe chemical (ref 1) and it works very well on most plants.
Glyphosate is absorbed by the leaves of growing plants and is transported to the roots. There, it slowly kills the roots and in turn the whole plant dies. This process is fairly slow, and usually takes 10 – 14 days for the plant to die.
Roundup vs Vinegar vs Salt
The above descriptions are basic facts about the three weed killers. I wanted to see them in action and be able to compare them to see how effective they really are.
I know Roundup works since I have used it in the past on a few very stubborn weeds including quack grass and bindweed. I have never used vinegar or salt.
In early spring, I dug out some good sized dandelions and potted them up. I took good care of them for a couple of months to make sure they were growing well. The picture below shows the three plants just before being sprayed with a weed killer.
Each pot was sprayed once with one of these: Roundup, pickling vinegar (7% acetic acid), and salt (1/4 cup sodium chloride per liter water).
After treatment, all three pots were added to my nursery of potted seedlings, which are watered every day unless it rains. They received sun most of the day, with a bit of shade late in the day.
Two weeks after spraying.
From experience, I know Roundup takes about 10 days to start showing results. Plants are usually dead at the 2 week mark. It looks like salt also did a good job and that was not unexpected. Salt, at high levels, is toxic to most plants. Vinegar had browned off the leaves a bit after spraying, but new ones soon grew back. The vinegar treated plant is smaller than before spraying, but is growing fine.
Eight Weeks After spraying
Does Salt Kill Weeds?
You can see from the above picture that the salt sprayed on the plant was not enough to kill it. Things might have been different if the plant had been in the ground. Salt is very soluble in water, and more watering means that it is washed away quicker. The plant would not have been watered as much if it was in the ground and so the salt might have stuck around longer, in turn killing the plant. But that is just a guess.
The salt treated plant is not nearly as large as the vinegar treated plant. So salt certainly affected the dandelion more than the vinegar spray.
Salt may be better at getting rid of weeds, but it is just not a good idea for treating weeds in the garden. Adding salt to your garden is not good for your plants or the environment.
Does Vinegar Kill Weeds?
The pickling vinegar did do some initial damage to the leaves, but it clearly did not kill the plant. This is consistent with scientific reports that say vinegar at 5% or 7% have very little effect on weeds that have well established root systems. See Vinegar Weed Killer Myth for more details.
Vinegar will not kill most weeds in the garden. 20% Acetic Acid does kill some weeds, but is not effective on all types.
In my next post I test vinegar’s ability to kill other types of weeds Vinegar Weed Killer Myth Revisited.
Will Vinegar + Salt Kill Weeds?
Some recipes recommend a mixture of both vinegar and salt. This is probably more effective than just vinegar alone, but again salt is just no good for the garden. I would not use it.
Many of you will have trouble believing me when I say Roundup is less damaging to the environment than salt. Roundup degrades fairly quickly as bacteria and is converted to water and CO2. Salt stays in the environment for ever.
references:
1) Glyphosate technical Fact Sheet: http://npic.orst.edu/factsheets/glyphotech.html
2) All photos by Robert Pavlis
If you wanna kill any plant weed or otherwise just over feed it burn it right up yes it will come back but weeds come back no matter what you do because they are parasites they want to take over. Salt kills for sure just look at the dead sea aint much growing around it, the word “Dead” should be a hint. If you wanna see the best stand of Bermuda grass just look where a diesel tank sat for 20 years on a farm / ranch yes its brown and dead for awile just like over fertilizing a garden but when it starts to break down the plants come back with a vengeance.
Great Article Robert, I have a Fenced gravel field where my dogs run (approximately 1 acre). I don’t want anything to grow in that area. What do you know regarding toxicity to animals?? I can easily isolate the yard from the dogs for a while if necessary. How long would you recommend??
Toxicity of Roundup is extremely low. But 12 hrs should be fine.
I find it curious that you’re such a strong proponent of RoundUp. Even minimizing the results of multiple trials, all of which found that the product causes cancer.
Actually, almost all government and health agencies have now declared glyphosate as non-cancer causing.
If you want to learn the truth, have a look at this discussion which included numerous references supporting my position. https://www.facebook.com/groups/GardenFundamentals/permalink/375650576238711/
“Recent studies report cancer links and concerns about validity of EPA classification:
February 2020 paper in Environmental Health, “A comprehensive analysis of the animal carcinogenicity data for glyphosate from chronic exposure rodent carcinogenicity studies,” reviewed chronic exposure animal carcinogenicity studies of glyphosate and reported toxicologically plausible pathways for why glyphosate may cause various cancers in rodents.
April 2019: the U.S. Agency for Toxic Substances and Disease Registry issued its draft toxicological profile for glyphosate, which reports an increased cancer risk from glyphosate exposures. Emails released via court proceedings show officials at EPA and Monsanto tried to hinder the ATSDR report.
March 2019 study published in the International Journal of Epidemiology analyzed data from more than 30,000 farmers and agricultural workers from studies done in France, Norway and the U.S., and reported links between glyphosate and diffuse large B-cell lymphoma.
February 2019: A meta-analysis published in Mutation Research/Reviews in Mutation Research reported a “compelling link” between glyphosate-based herbicides and non-Hodgkin lymphoma. Three of the study authors were members of the EPA’s scientific advisory panel on glyphosate who have stated publicly that the EPA failed to follow proper scientific practices in its glyphosate assessment.
January 2019: An analysis published in Environmental Sciences Europe argues that the U.S. EPA’s classification of glyphosate disregarded substantial scientific evidence of genotoxicity (the negative impact on a cell’s genetic material) associated with weed killing products such as Roundup.”
Source: https://usrtk.org/pesticides/glyphosate-health-concerns/
That site is very biased. Here are the facts: https://www.gardenmyths.com/truth-roundup-glyphosate/
“The active ingredient in Roundup is a chemical called glyphosate. Contrary to popular belief, this is a safe chemical and it works very well on most plants.”
The active ingredient is called glyphosate but it’s not glyphosate that’s the active ingredient in these products.
That’s what the article the Toxicology Reports journal published found. Glyphosate barely whitened the tomato plants treated but the “glyphosate” products truly did the “burn-down” on them!
They did it with all sorts of “inert” chemicals like POEA. Funny how nothing here mentions that one. The article tested POEA and found it to be 3,000 times more toxic than “active” ingredient glyphosate on human cells. Only 3,000 times… nothing to be concerned about. Oh, yeah… and arsenic, too.
Bait and switch at its finest. Perhaps most humorous was their finding that Syngenta sold a vastly safer glyphosate mixture in Hungary (Medallon) but only the super-toxic formulations in the USA. Syngenta clearly understands the US market, where countries like Hungary are better-managed (facepalm).
You really need to read that Toxicology Reports article and write a new post about so-called glyphosate (a Trojan horse). As it stands now, this article and your comments are erroneous marketing for the companies selling highly-toxic products, using glyphosate as a ruse. Trojan horse products are all the rage, like the “bentonite” bags filled with any amount of carcinogenic ultra-fine silica that companies want to dump into them.
Oh, and glyphosate products aren’t the only Trojan Horse herbicides. Look at clethodim, for instance. Diesel fuel and other petroleum distillates are a huge percentage of the formulation but all the safety exposure stuff is about the clethodim chemical itself. Clethodim can be used with a much less toxic solvent like ethanol, according to the scientific literature, but no one does that.
Where is your link that says glyphosate is not the active ingredient?
And why is glyphosate the patented ingredient in the product?
Bayer proposes $8 billion in settlements for roundup.
https://www.insurancejournal.com/news/national/2019/08/09/535359.htm
So what? That tells you nothing about the safety of the product. It does however tell you a lot about the court system in the US.
There are multiple dozens of cases against Bayer/Monsanto and the payouts are in the billions. It has been established that Roundup causes cancer.
You have the facts about the court cases wrong. https://www.gardenmyths.com/roundup-glyphosate-cancer-court/
Sprayed Round up(Grass and weed killer) on my paving stone side walk. waited 10 days (rained after 4 days) weeds didn’t die. Applied again, they yellowed shriveled like before and looked like they were dead. 3 weeks later the weeds were back with a vengeance. Reapplied new Roundup brush killer. Either I got a couple of bad batches, or my crabgrass is immune.
I used 75% vinegar with salt & dawn on overgrown weeds and got same day kill. I’ve had the same problem as Joan Goodell with Roundup not doing anything to the weeds. It is very frustrating.
Also purchased new Roundup.
Please Advise plantaholic
What is day kill? If a weed is dead for a day – it is not dead.
how do you explain the changes in the shikimate pathway that glyphosate makes happen? how do you explain the binding of trace minerals that glyphosate causes?
Glyphosate binds with one form of soil phosphate and causes another to leach into groundwater. I haven’t found any research that tests this problem to determine how much it contributes to things like the algae bloom problem in Lake Erie but it seems clear enough to correlate the two.
There is also the matter of polluting agricultural soil more by having to replenish the phosphate with “rock phosphate”. That is high in at least one heavy metal if not more than one. So, toxifying the soil by adding more heavy metal can be another bonus toxicity from glyphosate, a chemical that, according to an article published in the Toxicology Reports journal, isn’t even the true active ingredient and barely puts a dent in small tomato plants (for instance).
No one seems interested in connecting all the dots.
I’m from Canada where use of residential pesticides and herbicides have been banned now since last 10 years. We have weeds growing all around on public areas but studies show the water quality has improved significantly. I will use Double strength Vinegar, Salt, and dish washing soap as weed killing liquid on my yard even if I have to apply twice a month, at least I know there is no dangerous chemicals in there which big companies always lie about. I also use propane burner to kill weeds on my patio stone and interlock bricks. Both are environmentally friendly and super easy to use..
Neither of your solutions are environmentally friendly. The gas for your propane burner has to collected and may be the result of cracking. The vinegar, salt and soap all have to be manufactured and shipped to local stores. The containers become a waste product.
The salt consists of elements that can not be decomposed. They will flow into local rivers and lakes since it is very soluble.
And if a product is not working – how can you justify this environmental impact?
Guess what. Your round up is also transported by trucks using
gas etc.
True – but people don’t consider it environmentally friendly like all the household products.
If your farm has 4000 acres of soy beans and a thousand acres of corn in weed and bug infested southeastern USA. How much salt and vinegar would it take to kill the weeds and how would you control the crop destroying pests? Got a solution, That would be cost efficient enough to enable a profit, if not no more farmer, less food and more expensive food. Which would effect the amount of food lower income people could buy. This also applies to veggies and fruit crops. Would also impact the USA and the world as a whole.
What’s a better solution for Agri-business?
Anecdotal experience does not qualify one to so quickly dismiss independently sourced scientific research that demonstrates Roundup’s dangers. I spent many years developing pesticides for Dow Chemical (chlorpyrifos and 24-D/245-T) and Velsicol Chemical (chlordane) and I can attest to the fact that Roundup’s risks have been well known within the agricultural community for decades.
It’s no oversimplification to state that pesticides are designed for a single purpose, to kill the target pest be it weed or bug. Pesticides act by disrupting key metabolic, endocrine or chemical reactions within the target pest thereby killing it. It is only human hubris that leads us to cling to the belief that the human body is immune to effects of chemical compounds specifically designed to be toxic to lower order species.
Used according to labeled instructions, we’re led to believe pesticides are safe, they are not. Little research, beyond LD50 is performed by manufacturers to determine the impact of long term, low dose exposures to the casual consumer end-user. The majority of weekend gardeners fail in using even basic protective measures like gloves or dust masks. Dermal absorption and inhalation are primary routes of exposure for all pesticides.
And, every individual will react differently to a chemical exposure. Some will have no reaction while others will experience severe reactions. These are usually transitory reactions however, we know the human body stores some small portion of everything that enters into it. The cumulative toxicity of pesticides is not fiction but fact. A individual with an impaired immune response due to an underlying health condition, viral or bacterial exposure or recent physical trauma, will have a lowered immune response that impairs the body’s capacity to metabolize and excrete toxins.
Few would dispute Roundup is an excellent non-selective herbicide. Its herbicidal performance however does not diminish its toxicity or preclude the compound’s carcinogenic potential. Science will ultimately settle the issue, in the interim consumers should be highly skeptical of any industry studies that history teaches us, are always biased in favor of the company paying for the studies.
The presented experiment did NOT make any comment on or conclusions about the safety of Roundup. It simply showed it does work
As far as glyphosates carcinogenic potential, and as you say “lack of studies”, there have no been thousands of studies, and none of shown it is causing cancer in animals. Even the world health association reached this conclusion, when it did not find evidence to label it as cancer causing.
Regarding Roundup the author wrote, and I quote, “Contrary to popular belief, this is a safe chemical.”
In early April, Monsanto was ordered to pay damages to a Sonoma County man after Roundup was found to be a substantial factor in the development of the plaintiffs cancer. A similiar verdict was reached last year in San Francisco. Over two dozen countries have banned or restricted the use of glyphosate.
And you are wrong about the WHO. They came to the conclusion that it “probably” causes cancer.
The court case means nothing. The decision was a jury decision, made up of average people who do not have the knowledge or experience to evaluate scientific research.
Countries are banning gylphosate because governments do what gets them elected.
The fact that something works, as you mentioned, is not reason enough to condone it’s use. I mean, guns work too but clearly they’re not intended for broad use applications.
Besides, there’s more than enough scientific evidence to show the link between gylphosate and bee colony collapse that makes it clear Roundup should not be used.
https://www.sciencedirect.com/science/article/pii/S2214574515000851
Without the bees, you won’t need any farms…
There is no connection between collany collapse and glyphosate. We don,t need bees to produce food on farms since most of it is not pollinated by bees.
While being cautious about Roundup and its clones, I do recall lots of court cases that hit Dow, which also found the company liable for cancer, and a multitude of other disease causing breast implants (not talking about the ones that tore and leaked). Later found to be average-Joe folklore. Court decisions can be right, or dead wrong.
True, but court cases show the opinion of the jury not the science.
https://www.gardenmyths.com/roundup-glyphosate-cancer-court/
The court case I watched here, https://www.youtube.com/watch?v=qVXPNPpRGz4, about said a man who developed cancer was using Roundup since the 80’s and was diagnosed with cancer in 2015. That’s 35 years of spraying this stuff around and probably getting it on his skin and inside his lungs. Obviously, with that kind of continuous exposure, it certainly played a role with his health problems but as consumers, we need to be mindful and use moderation and safe practices with everything we use. I don’t think the occasional household use and exposure to pesticides and pollutants is equal to someone who works in with pollutants all the time.
The man in the original lawsuit only used it for a couple of years – not enough time to cause a cancer.
But that is not the main point. Just because someone uses the product and gets cancer does not provide the product causes cancer. Lots of people get the same cancer and have never used the product. That is why we have scientific studies that look at large pools of people.
When a large group of farm works were reviewed after using glyphosate for years, there was no increase in cancer rates compared to the general public.
Glyphosate has been classified by the World Health Org as a cat 2A (probably carcinogenic to humans). I doubt the 2 gallons someone uses around the house every year would provide any danger to a human, but you must remember that it is widely used in agriculture, so there’s glyphosate in just about everything we eat. It adds up, IMHO. I’ve used a combo of vinegar with dish soap and epsom salt to great success, provided it may take a second application after about a week.
So if it takes a second application – it did not work the first time!
When you take an antibiotic, you take it for 7-10 days. The fact that you take more than one dose does not mean that it doesn’t work.
I don’t see the connect between this and the article? People are not promoting the idea to spray vinegar for 7-10 days – they claim weeds are dead after 1 spraying.
What strength vinager?
Andrei that was the IARC, the WHO made this statement: “A new report from the United Nations (UN) and World Health Organization (WHO) has concluded that the controversial pesticide glyphosate is ‘unlikely to pose a carcinogenic risk to humans from exposure through the diet’.” https://www.chemistryworld.com/news/who-clarifies-glyphosate-risks/1010208.article
Why did Bayer loose the court cases concerning Roundup? They lied and had ghost writers help them. Just google Monsanto Ghost Writers. Or look at “Spinning Science & Silencing Scientists”, a study done by Congress that shows how Monsanto has been lying to us for years. 16 scientists from 4 independent panels signed their names to published works that Roundup was safe. They signed papers that they were independent from Monsanto. Through the disclose of Monsanto’s documents It was shown that the research was conceptualized as a deceptive strategy. One of Monsanto’s top scientists not only reviewed the studies but had a hand in drafting and editing them. In one internal email, Monsanto’s chief of regulatory science, William Heydens, said, “I have gone through the entire document and indicated what I think should stay, what can go, and in a couple spots I did a little editing.” The EPA used this bad science for research on glyphosate.
Why did Tufts Vet. school find that cancer in dogs has gone up 70%. Dogs have 5000% more glyphosate in them than humans. Tufts blames the cancer in dogs from herbicides (Roundup). In 2015 the EPA said that because of unacceptable levels of the insecticide in food and drinking water it planned to ban the pesticide from agricultural use. But pressure from chemical industry lobbyists have kept the chemical in wide use on American farms. In 1993, for example, the EPA had a tolerance for glyphosate in oats at 0.1 parts per million (ppm) but in 1996 Monsanto asked EPA to raise the tolerance to 20 ppm and the EPA did as asked. In 2008, at Monsanto’s suggestion, the EPA again looked to raise the tolerance for glyphosate in oats, this time to 30 ppm. Money talks, Bayer spends 8 million a year for lobbyists. Check on your childre’s cereal. The highest level of glyphosate found by the lab was 2,837 ppb in Quaker Oatmeal Squares breakfast cereal, nearly 18 times higher than EWG’s children’s health benchmark. Please do your homework, read the trial reports. Roundup will be the new asbestos.
The court case proves nothing. It is simply the opinion of the general public, who on this subject is poorly informed.