Glyphosate and trees

[Tom Joye]

Hi,

anybody has got any information on the effect of using glyphosate in the root zone of trees? In contradiction to common beliefs, glyphosate apparently does accumulate in the soil and in the tree, but I do not find much (scientific) information on this topic.

Thanks in advance,

Tom

[Mesterh]

All I know is that we use it to poison tree stumps and always say to customers if it grows back call us and we will re poison for free.

Never had a return call about regrowth and no one has ever complained that it has killed any other trees/plants that I know of.

[18 stoner]

Glyphosate is a Foliar Acting, Systemic Herbicide. It is therefore designed to be mixed according to instructions and foliarly applied, the plant then takes the chemical to its root system and therefore kills the plant.

 

The chemical was originally designed and patented, marketed only under the brand name of "Roundup". After the patented period expired many other companies started marketing the chemical, also as a stump killer.

 

It is safe to use under tree canopies for weed treatment, however contact with foliage at lower concentrations can still scorch trees, shrubs and hedges, but should not affect bare stems.

 

In high concentration it will kill stumps and brush, but is a crude way of doing it as transfer is possible to other plants.

 

Hope this helps a bit!

[Albedo]

I posted in another thread that it kills of mychorrizae and that you'd get reduced growth as a result, and promised phenom that I'd find the reference where I'd read about it. Looked high and low in my papers and on the net and can't find any articles on it.

 

With regard to it being foliar acting, there is dispute over whether it should work as a stumpicide. Logicaly, if applied to the leaves it would travel thru the tree to the roots using the trees vascular system. So any method of introducing it into the vascular system should work.

 

As Stoner says it was Monsanto that originally patented it, when the patent expired they developed GM roundup resistant crops, in order to keep a handle on the market for the product in agriculture.

 

I've read that there are soil residues but, can't find references. Will probably have another look now.

Edited December 24, 2008 by Albedo
change stockers to stoner

[Albedo]

quote 18 stoner -It is safe to use under tree canopies for weed treatment,

 

 

I would dispute this, for reason mentioned above, but admit I don't have the evidence. Might be an idea to try to nail this one as its used for vegetation control around trees, we've all done it.

 

The question would be, do mychorrizae have a mechanism for ingesting glyphosate? Does the foliar acting bit mean, via stomata thru evapotranspiration mechanisms, and if so what mechanism do mycho's have to do the same

[Nomad]

I don't think you should spray the root zone of trees until at least the third year after planting. Probably your best bet on finding relatively un-biased scientific data would be the Scandanavians, they don't like Glyphosate.

[Tom Joye]

Well, it was developed as a foliar herbicide, but I know some street trees that died because of herbicide accumulation in the soil and in the plant. Two herbicides were identified: amytrol and glyphosate. So I'm pretty sure it might actually kill a tree, even without foliar contact, with only soil accumulation. And that's why IMO no herbicides should be used in the root zone of trees (or at all actually).

But up until now it's more a gut feeling than based on scientific data. So that's what I was looking for.

[Nomad]

Go with your instincts

Have a look at these for starters.

 

http://www.abcbirds.org/abcprograms/policy/pesticides/Profiles/glyphosate.html

 

http://www.rag.org.au/modifiedfoods/roundup

[Tom Joye]

Go with your instincts

Have a look at these for starters.

 

http://www.abcbirds.org/abcprograms/policy/pesticides/Profiles/glyphosate.html

 

http://www.rag.org.au/modifiedfoods/roundup

 

Thanks Nomad,

Great info!

[Quickthorn]

I don't think you should spray the root zone of trees until at least the third year after planting.

 

Spraying a square metre or so around newly planted trees using glyphosate is very, very common forestry practice, and is often done for the first three years after planting. I do a lot of this each spring, and I can't say I've noticed that it's been having a bad effect. If I choose the herbicide, I normally choose glyphosate because the risk of run-off is lower, the product breaks down into reasonably safe compounds and it is normally the safest for the operator (some glyphosate products do not even carry a CHIPS label). My personal belief is that a directed spray will not harm young trees, providing it is applied as instructed on the label. 4 l/ha product is normally enough for most situations; lower doses can often be used, depending on what weeds are present.

Edited December 24, 2008 by Quickthorn