Use of glyphosate is something that comes up often on the HomeOne Landscaping forum and here's one particular topic that I've been involved in.
This discussion was initiated by Lex, a member who was concerned about glyphosate being used to kill off the old grass in her garden, before her new turf was laid. There are two methods generally used for the removal of old turf in Australia: the rip and strip method, where a mechanical ripper or a digger will be used to effectively scrape off the turf and existing topsoil; and the glyphosate method, whereby the whole area is sprayed, perhaps repeatedly, and poisoned.
Both methods have their issues, but if you are determined to replace your turf then you will need to settle for one or the other. The rip and strip method is expensive and time consuming, though it can be done by hand. Good luck on finding a turf contractor willing to do this!
The glyphosate method is cheap and involves little time commitment from the contractor. You simply spray, wait and then perhaps spray again. This is why it's the method most often used.
The problem with wholesale use of glyphosate products in the home garden comes when these are used by untrained individuals, or those who are in too much of a hurry to finish a job and maximise profits, rather than exhibiting due care and attention to detail.
Anyway, I don't want to go into that at the moment, nor do I want to repeat what I already posted, so please forgive me the cut and paste [edited slightly to make it seem less of a rant!]:
"Glyphosphate products are not safe it's just safer for humans (mammals) than other herbicides. Yes, it will likely kill any creatures such as worms, snails, slugs, frogs and other amphibians, probably reptiles, and definitely fish that it comes in contact with.
It is not so much the Glyphosphate that is an issue, but the surfacants (such as polyoxyethylene amine or POEA) that are used to encourage take up of the Glyphosphate by the plants targeted. Glyphosphate bonds to certain plant enzymes and prohibits them from creating the proteins necessary to synthesise food and grow. The POEA breaks down the wax-like coating on the plant leaves etc to allow better penetration of the glyphosphate. This is why it's suggested to add a couple of drops of detergent to the solution - it does the same thing
The Glyphosphate itself, has an LD50 (the amount required to provide a lethal dose to 50% of a test population over a set timeframe) that is quite high for most mammals (10,000mg/kg for mice, over 5,000mg/kg for rats, 3,800mg/kg rabbits and over 3,500mg/kg for goats). The POEA however has a much lower LD50, meaning far less of it is needed to be eaten to give a lethal dose (the figure for rats is around 1,300mg/kg).
There are no figures from testing toxicity of POEA on other mammals that I can find, though I have found some information on dogs being poisoned (some dogs and cats have died from ingesting Glyphosphatesprayed at agricultural levels in the UK). The absorption of Glyphosphate into the bodies tissues from the intestines is pretty poor and rates within the tissues remain low, meaning that the Glyphosphate itself is pretty low on the scale as a toxin. Again, there are no figures recorded for the POEAs.
The reason Glyphosate is so popular is that it is a broad range herbicide, that is termed an organophosphate. It has a low toxicity (to mammals as above), doesn't last in the soil and therefore does not bioaccumulate (it is biodegradable). This means that your soil will return to full health almost immediately, so no long term effects will be felt from that point of view. This is why organic gardeners have been using it for decades.
This is based on the active ingredients detailed on the patent and licensing i.e. the actual herbicidal components, or glysophate. Funnily enough, the company who originally patented Glyphosphate (under the TM Roundup...look it up), didn't feel the need to mention the POEAs on the original licensing application, so no testing was done.
The active constituents of herbicides currently in common use are exposed to reasonably rigorous toxicological scrutiny during their developmental stages, and their approval for release in Australia hinges upon an assessment of their action upon non-target organisms such as frogs.
The POEA is not considered the 'active ingredient' as it isn't what kills the plants, that's the glyphosphate. Therefore the POEA doesn't have to be regulated.
POEA is one of many, many detergents and surfactants that have been created to have similar structures and properties as soap. Detergents don't react in the same way with minerals like calcium and magnesium that are found in hard waters, so are more effective than soaps in certain situations. Unfortunately, they have pretty complex molecular structures, made up of chains of lots of other compounds (soap, zeolites, chalk, bleaches, perfumes, various enzymes to break down different fats, carbs and proteins, lots of other things and of course, phosphates). These chains of molecules pretty much mean that the majority of detergents (NOT ALL) are not biodegradable and build up in the soil and particularly waterways.
We all know that phosphates and waterways are not a good combination. Phosphates are causing increased algal growth, toxic water, dead areas....
An Australian study confirmed that glyphosate-based herbicides are toxic to frogs, especially tadpoles, possibly because of the effect of the dispersant on tadpole gills (Bidwell and Gorrie 1995). The authors recommended that a list of low impact dispersants suitable for use in aquatic environments be developed. The National Registration Authority has responded to this report, and from July 1997 a total of 74 herbicide preparations were banned from use near water.
In the EU, they passed a law several years ago requiring all detergents to be biodegradable and have requirements in place for phosphates to be phased out completely in the near future. There are several very good products in Australia that have no phosphates, low levels of salts, are made mostly from plant based surfacants that are certified biodegradable to Australian Standards. I would recommend you use one of these, regardless of whether or not you have a septic tank or greywater system at home.
In the EU, they passed a law several years ago requiring all detergents to be biodegradable and have requirements in place for phosphates to be phased out completely in the near future. There are several very good products in Australia that have no phosphates, low levels of salts, are made mostly from plant based surfacants that are certified biodegradable to Australian Standards. I would recommend you use one of these, regardless of whether or not you have a septic tank or greywater system at home.
Studies also show that phosphates also build up in the soil and react with other essential minerals and nutrients, preventing their take up by plants. It means plants can become deficient in particular nutrients, even though there is an abundance of them in the soil. They're just not 'available' to the plants' roots anymore because they're locked up by the phosphates etc. This is why using chemical fertilisers creates a spiral of dependancy, with more and more needing to be used to keep crops growing.
Lets not even mention glyphosate resistance that is appearing in several weeds, which means that the genes from the 'roundup ready' plants are jumping ship.
Anyway, back OT...
You are right to be concered about using any chemicals on your garden. Roundup has been found to remain in soils for over a year and longer in waterways. This is due to the combination of all the chemical compounds in it. The company that made Roundup were actually sued for falsely claiming it was biodegradable. Most of it is... eventually...
The risks of using Roundup and other similar products are reduced greatly if you take heed of the precautions (it should be used only when it's dry out, there's no surface water, it's not going to rain in the next 24 hours, preferably longer, and it's a completely still day. And do not let it get into the drains!!).
Also, your soil type can be taken into account to determine whether the Roundup you spray on your garden will get into the groundwater, and eventually the creeks, rivers, lakes, seas and oceans. Clay soil tend to attract particles because of the negative charge they possess (same to with soils high in humus), including Roundup, which bind with it. It pretty much remains in the soil, though can still be taken up by plants. Sandy soils allow minerals and nutrients to wash away into the groundwater when it rains.
Most sources I've read, including the US Environmental Protection Agency's RED report, say that research has shown Roundup will not harm mammals who consume plants that have taken up Roundup through the soil as it does not make it into the tissues.... only people who have directly ingested it, or dogs who have eaten plants that have just been sprayed with it, have become ill.
I have searched and I suspect that the only way you can buy pure glyphosate is if you needed it for production purposes. Plus, without the POEA it wouldn't work as well.
I understand the concerns about poisoning huge areas of lawn (repeatedly in the case of the kikuyu, which often needs repeated applications) and personally, I wouldn't do it but that's because I am happy to have a 'weed' infested lawn and dig anything that's a problem out the old fashioned way. If you're relaying a whole lawn however, as long as you ensure that all precautions are taken, the use of glyphosate shouldn't cause you too many sleepless nights.
I have searched and I suspect that the only way you can buy pure glyphosate is if you needed it for production purposes. Plus, without the POEA it wouldn't work as well.
I understand the concerns about poisoning huge areas of lawn (repeatedly in the case of the kikuyu, which often needs repeated applications) and personally, I wouldn't do it but that's because I am happy to have a 'weed' infested lawn and dig anything that's a problem out the old fashioned way. If you're relaying a whole lawn however, as long as you ensure that all precautions are taken, the use of glyphosate shouldn't cause you too many sleepless nights.
[NB: I have since this statement used Roundup to kill off Kikuyu in the area where we were installing raised veg beds. This was done with a very, very dilute solution at the start of a hot period of sunny, dry, calm weather and was repeated one week later. The Kikuyu and everything else growing in those areas were killed off within 2 weeks. I have not noticed any long, or short term, effect on the biota in that area, but am still unhappy with the method and in future will likely solarise any such areas that need clearing.]
I would emphasise the precautions though. Seriously. They are there for a reason.
As for the 'organic' thing. Organic gardeners, along with millions of us the world over, were fooled by Roundup. Simple as that. It took a while for the POEA issue to come to light. I believe it was the deaths of tadpoles in a particular Australian water way and the appearance of resistant weeds in NSW that starting people wondering, but it might have been earlier than those incidents.
I tend to dig out weeds where possible, but have resorted to Zero to die back particularly large infestations of rampant weeds (Wandering Trad in particular) before using a dutch hoe and hand fork to remove what is left in the soil. In those cases I used much lower concentrations than recommended. I still find the snails die that are directly sprayed, but it doesn't seem to affect the earthworms, grubs, fleas, jumping jacks, ants, millipedes, centipedes, various beetles and all other manner of beasties in my soil.
As for nutgrass, this is one of the plants I believe are becoming resistant to Glyphosphate (along with Agapanthus!!!). If you want to get rid of it, you need to get out all the underground 'nuts' (they grow in the roots as tubers). I have used a fork to dig out all the nutgrass in my 'lawn' (ahem) and still have bits of it popping up from seed that's made it's way in. I simply dig it out each time and then take a plug of clover from elsewhere in my lawn and plant it in that spot. The gaps fill in fairly quickly.
For a rubble strewn garden, I would remove all the rubble first, dig areas over (a patch at a time) removing everything I found, then use a rake and dutch hoe to remove everything I missed. A soil sifter is good for small things like Oxalis corns (aargh, I'll be fighting this stuff forever!!!!). Then plant that area. So, if you want a veg bed, clear that area and get the bed in and planted, then move on. It will take a while, but the results will be much more likely to be weedfree.
If you want to be completely chemical free when it comes to weeds or any other plant removal, you need to dig them out. It's hard work, but damn satisfying!
I would emphasise the precautions though. Seriously. They are there for a reason.
As for the 'organic' thing. Organic gardeners, along with millions of us the world over, were fooled by Roundup. Simple as that. It took a while for the POEA issue to come to light. I believe it was the deaths of tadpoles in a particular Australian water way and the appearance of resistant weeds in NSW that starting people wondering, but it might have been earlier than those incidents.
I tend to dig out weeds where possible, but have resorted to Zero to die back particularly large infestations of rampant weeds (Wandering Trad in particular) before using a dutch hoe and hand fork to remove what is left in the soil. In those cases I used much lower concentrations than recommended. I still find the snails die that are directly sprayed, but it doesn't seem to affect the earthworms, grubs, fleas, jumping jacks, ants, millipedes, centipedes, various beetles and all other manner of beasties in my soil.
As for nutgrass, this is one of the plants I believe are becoming resistant to Glyphosphate (along with Agapanthus!!!). If you want to get rid of it, you need to get out all the underground 'nuts' (they grow in the roots as tubers). I have used a fork to dig out all the nutgrass in my 'lawn' (ahem) and still have bits of it popping up from seed that's made it's way in. I simply dig it out each time and then take a plug of clover from elsewhere in my lawn and plant it in that spot. The gaps fill in fairly quickly.
For a rubble strewn garden, I would remove all the rubble first, dig areas over (a patch at a time) removing everything I found, then use a rake and dutch hoe to remove everything I missed. A soil sifter is good for small things like Oxalis corns (aargh, I'll be fighting this stuff forever!!!!). Then plant that area. So, if you want a veg bed, clear that area and get the bed in and planted, then move on. It will take a while, but the results will be much more likely to be weedfree.
If you want to be completely chemical free when it comes to weeds or any other plant removal, you need to dig them out. It's hard work, but damn satisfying!
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