Round-Up is only glyphosate. It’s biodegradable, in fact it’s broken down very quickly once it hits the soil. That’s why it only works if you get it on the leaves.
Wiki has a long section on it, and although it’s mixed, it’s hardly all good news:
"Health, ecological concerns and controversy
*[edit] Toxicity and ecological impact
Glyphosate is classed as a moderately toxic herbicide and in EPA toxicity class III. A 2000 review of the available literature concluded that “under present and expected conditions of new use, there is no potential for Roundup herbicide to pose a health risk to humans”.[10] The Northwest Coalition for Alternatives to Pesticides disputes this classification.[11]
[edit] Scientific fraud and false advertising
On two occasions the American EPA has caught scientists deliberately falsifying test results at research laboratories hired by Monsanto to study glyphosate.[12][13][14] In the first incident involving “Industrial Biotest Laboratories”, a reviewer stated after finding “routine falsification of data” that it was “hard to believe the scientific integrity of the studies when they said they took specimens of the uterus from male rabbits”.[15][16][17] In the second incident of falsifying test results in 1991, the owner of the lab (Craven Labs), and three employees were indicted on 20 felony counts, the owner was sentenced to 5 years in prison and fined 50,000 dollars, the lab was fined 15.5 million dollars and ordered to pay 3.7 million in restitution.[18][19][20] Craven laboratories performed studies for 262 pesticide companies including Monsanto. Monsanto has been accused of false and misleading advertising of glyphosate products, prompting a law suit by the New York State attorney general.[21] Monsanto has also been accused of the false advertising of roundup in Europe where it is currently appealing a law suit on the issue.[22]
[edit] Human and mammalian toxicity
Outside its intended use, glyphosate can be lethal. For example, with intentional poisonings (e.g. suicide), there is approximately a 10% mortality for those ingesting Roundup, compared to 70% for those ingesting paraquat.[23]
A review of the toxicological data on Roundup shows that there are at least 58 studies of the effects of Roundup itself on a range of organisms.[24] This review concluded that “for terrestrial uses of Roundup minimal acute and chronic risk was predicted for potentially exposed nontarget organisms”. It also concluded that there were some risks to aquatic organisms exposed to Roundup in shallow water. More recent research indicates glyphosate induces a variety of functional abnormalities in fetuses and pregnant rats.[25] Also in recent mammalian research, glyphosate has been found to interfere with an enzyme involved testosterone production in mouse cell culture[26] and to interfere with an estrogen biosynthesis enzyme in cultures of Human Placental cells.[27]
In controlled residue studies the WHO found “significant residues” on wheat with residues not lost during baking.[28]
Concerns have been raised abouts Roundup’s effect on flora, mammals and birds brought about through habitat destruction.[29]
The United States Environmental Protection Agency,[30] the EC Health and Consumer Protection Directorate, and the UN World Health Organization have all concluded that pure glyphosate is not carcinogenic. Opponents of glyphosate claim that Roundup has been found to cause genetic damage, citing Peluso et al.[31] The authors concluded that the damage was "not related to the active ingredient, but to another component of the herbicide mixture.
[edit] Aquatic effects
Fish and aquatic invertebrates are more sensitive to roundup than terrestrial organisms.[24] Glyphosate is generally less persistent in water than in soil, with 12 to 60 day persistence observed in Canadian pond water, yet persistence of over a year have been observed in the sediments of ponds in Michigan and Oregon.[32]
Roundup is not registered for aquatic uses[33] and studies of its effects on amphibians indicates it is toxic to them.[34] Glyphosate formulations that are registered for aquatic use have been found to have negligible adverse effects on sensitive amphibians.[35]
[edit] Environmental degradation and effects
When glyphosate comes into contact with the soil it can be rapidly bound to soil particles and be inactivated.[32] Unbound glyphosate can be degraded by bacteria.[36] Low activity because of binding to soil particles suggests that glyphosate’s effects on soil flora will be limited.[citation needed] Low glyphosate concentrations can be found in many creeks and rivers in U.S. and Europe,[citation needed] and in the US glyphosate has been called “relatively persistent” by its EPA.[32]
In soils, half lives vary from as little as 3 days at a site in Texas, 141 days at a site in Iowa, to between 1 - 3 years in Swedish forest soils.[37] It appears that more northern sites have the longest soil persistences such as in Canada and Scandinavia.
However, the binding of glyphosate to particulates can be an advantage. Treatment of industrial wastewater using immobilized bacteria showed complete conversion of glyphosate to nontoxic aminomethylphosphonic acid.[38]
The US EPA concluded that many endangered species of plants, as well as the Houston toad, may be at risk from glyphosate use.[citation needed] One study has shown an effect on growth and survival of earthworms.[39] The results of this study are in conflict with other data and has been criticized on methodological grounds.[24] In other studies nitrogen fixing bacteria have been impaired, and also crop plant susceptibility to disease has been increased.[40][41][42][43][44][45] Monsanto firmly denies any negative impact on anything, including wildlife, and has many studies it has funded to back up its position. They would also be quick to point out that any possible negative impact on earthworms and nitrogen fixing bacteria, etc., would be offset by greater yields as of the elimination of weeds, and also would point to soil benefits from less mechanical cultivation of weeds by using Roundup and similar products.
[edit] Reproductive health concerns and EDC activity
There are concerns about the effects of glyphosate (and Roundup) on possible human reproductive dysfunction.
[edit] Endocrine disruptor debate
In-vitro studies[46] have shown glyphosate to have an effect on progesterone production in mammalian cells and can affect mortality of placental cells in-vitro.[27] Whether these studies classify glyphosate as an endocrine disruptor is a matter of debate.
Some feel that in-vitro studies are insufficient, and are waiting to see if animal studies show a change in endocrine activity, since a change in a single cell line may not occur in an entire organism. Additionally, current in-vitro studies expose cell lines to concentrations orders of magnitude greater than would be found in real conditions, and through pathways that would not be experienced in real organism.
Others feel that in-vitro studies, particularly ones identifying not only an effect, but a chemical pathway, are sufficient evidence to classify glyphosate as an endocrine disruptor, on the basis that even small changes in endocrine activity can have lasting effects on an entire organism that may be difficult to detect through whole organism studies alone. Further research on the topic has been planned.
[edit] Glyphosate resistance in weeds and microorganisms
The first documented cases of weed resistance to glyphosate were found in Australia, involving rigid ryegrass near Orange, New South Wales.[47] Some farmers in the United States have expressed concern that weeds are now developing with glyphosate resistance, with 13 states now reporting resistance, and this poses a problem to many farmers, including cotton farmers, that are now heavily dependent on glyphosate to control weeds.[48][49] Farmers associations are now reporting 103 biotypes of weeds within 63 weed species with herbicide resistance, and this will continue to grow as a problem.[50][51]
Some microorganisms have a version of 5-enolpyruvoyl-shikimate-3-phosphate synthetase (EPSPS) that is resistant to glyphosate inhibition. The version used in genetically modified crops was isolated from Agrobacterium strain CP4 (CP4 EPSPS) that was resisitant to glyphosate.[52][53] The CP4 EPSPS gene was cloned and inserted into soybeans. The CP4 EPSPS gene was engineered for plant expression by fusing the 5’ end of the gene to a chloroplast transit peptide derived from the petunia EPSPS. This transit peptide was used because it had shown previously an ability to deliver bacterial EPSPS to the chloroplasts of other plants. The plasmid used to move the gene into soybeans was PV-GMGTO4. It contained three bacterial genes, two PC4 EPSPS genes, and a gene encoding beta-glucuronidase (GUS) from Escherichia coli as a marker. The DNA was injected into the soybeans using the particle acceleration method. Soybean cultivar A54O3 was used for the transformation. The expression of the GUS gene was used as the initial evidence of transformation. GUS expression was detected by a staining method in which the GUS enzyme converts a substrate into a blue precipitate. Those plants that showed GUS expression were then taken and sprayed with glyphosate and their tolerance was tested over many generations."
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In other words, it’s stuff that should *not *be used casually, where a little sweat woudl do the job as well. It should not be used where it will drain into creeks, and other natural waterway. OTOH, it’s hardly Agent Orange. But for a little Mint? No way.
Here in the Willamette valley there are big old farms that raise mint specifically for making compost. It grows fast, makes a large volume of biomass and smells fabulous when it decays. So no, mint did not make your soil inhospitable, except insofar as it will choke the life out of less aggressive plants.
There’s no easy way to get rid of it, you just have to keep on pulling it… On the plus side, if you compost it well it will put a lot of life and vigor back into your soil. Offhand, I’d say you probably overtilled quite a bit, rototilling down a foot is pretty drastic, especially if you didn’t put a bunch of soil amendments in when you tilled.
Mint is not herbicidal. Rototilling it vigorously might destroy it, but it’s so tough and invasive that you may not have seen the last of it.
Adding appropriate soil amendments including compost will help restore the health of your soil.
While I am not a huge fan of Roundup, the Wikipedia article overstates hazards associated with this product. In limited use, it is a relatively safe product. Using it is surely a lot more friendly to the environment than virtually any other herbicide (including salt - do NOT use salt).
Mint laughs at Round up! Its totally ineffective against mint. You’ll waste your time and money using it.
You have to bury mint under SEVERAL inches of top soil or compost to kill it.
Get some cats to take care of it.
<stoned cat> catnip! catnip! CATNIP! </stoned cat>
Mint, they don’t know it’s not catnip.
Okay, so catnip is a mint. I discovered this when my cats went nuts on my mint plant, so I put it outside where a neighbor cat finished off the poor thing.