In message , Rodger Whitlock
writes
On Sat, 2 Aug 2003 18:58:36 +0100, PA wrote:

I've a lot of couch grass to clear...


After reading a number of other replies, let me suggest an
alternative, organic approach. It depends on the fact that couch
grass likes to have its rhizomes just below the soil surface.

It is a reasonable trick. If you have the time and inclination.

Cover the infested area with black plastic sheeting and wait.

The black plastic method may have another effect: if the soil
underneath gets hot enough from the sun, it will just cook the
couch rhizomes.

There is one slight catch though. The overall environmental impact of
making all that black plastic sheet is greater than that of the tiny
amount of glyphosate needed to achieve the same effect.

Regards,
--
Martin Brown

On Sun, 3 Aug 2003 23:15:36 +0100, Martin Brown wrote:

There is one slight catch though. The overall environmental impact of
making all that black plastic sheet is greater than that of the tiny
amount of glyphosate needed to achieve the same effect.

I am quite prepared to believe this. A professor of applied
chemistry at our local university once worked out the total
inputs of non-renewable and renewable resources into the
manufacture of the hated styrofoam coffee cups and the more
favored paper cups, respectively. He concluded that stryofoam
cups, overall, use fewer/less non-renewable resources than do
paper cups, contrary to popular belief.


--
Rodger Whitlock
Victoria, British Columbia, Canada

In article , Martin Brown
writes
Please provide evidence that trace glyphosate metabolites have been used
to revoke Organic(TM) grower licences. I can just about believe it has
happened given how crazy UK supermarket driven agriculture has become.

In this area agricultural crops are grown on marshland. Some of the time
the land is too wet for wheeled farm vehicles, so spraying is carried
out by light aircraft. Local beekeepers are warned when spraying is to
be carried out, but organic growers are not. Spray drifting is a well
known hazard, and has been the cause of licences being lost.
--
Alan & Joan Gould - North Lincs.

In article ,
PA wrote:
thanks every one for your input, I'm still in two minds though....
the bit I don't get is: if no residue is left in the soil, what about when
the roots of the weeds start to break down wont they release chemicals,
which will be then taken up by whats ever growing?
the trouble is I've got about 450 square meters to clear and its taken about
an hour to do one properly
and now I'm dreaming of roots

No, because it will be released into the soil, where it will be broken
down by bacteria. Apparently, some breakdown products disappear very
slowly from the anaerobic sludge at the bottom of ponds, but garden
soil has a very different (and much more vigorous) collection of
microorganisms.


Regards,
Nick Maclaren.

"Martin Brown" wrote in message
...

[snip]

A few very tough weeds with large deep roots and small tough waxy leaves
can survive it (and for some reason buttercup is partially resistant).

[snip]

Glyphosate is ever so slow in action compared to paraquat. I use both
according to my mood, and (because of my impatience?) I usually have to
apply glyphosate twice before the weeds keel over.

Does paraquat really put paid to a plant, root and all, or does it only
interfere temporarily with the photosnthesis in the leaves?

[Franz Heymann]

"Martin Brown" wrote in message
...
In message , Rodger Whitlock
writes
On Sat, 2 Aug 2003 18:58:36 +0100, PA wrote:

I've a lot of couch grass to clear...


After reading a number of other replies, let me suggest an
alternative, organic approach. It depends on the fact that couch
grass likes to have its rhizomes just below the soil surface.

It is a reasonable trick. If you have the time and inclination.

Cover the infested area with black plastic sheeting and wait.

The black plastic method may have another effect: if the soil
underneath gets hot enough from the sun, it will just cook the
couch rhizomes.

There is one slight catch though. The overall environmental impact of
making all that black plastic sheet is greater than that of the tiny
amount of glyphosate needed to achieve the same effect.

Touche

[Franz Heymann]

In article ,
(sw) writes:
|
| No, because it will be released into the soil, where it will be broken
| down by bacteria. Apparently, some breakdown products disappear very
| slowly from the anaerobic sludge at the bottom of ponds, but garden
| soil has a very different (and much more vigorous) collection of
| microorganisms.
|
| I'd thought there was some research suggesting it doesn't break down in
| soil quite as thoroughly/quickly as was originally believed? Or is that
| more a concern where fields of GM-HT crops are resulting in higher
| usage?

The research I have seen was mainly to do with anaerobic sludge.

I believe that your statement is correct in general, but the
original claim was "completely within days" and the current one
is more like "completely, eventually, but with timescale of some
months". However, I have seen only indirect reports on the latter.


Regards,
Nick Maclaren.

"sw" wrote in message
...
Nick Maclaren wrote:

In article ,
PA wrote:
thanks every one for your input, I'm still in two minds though....
the bit I don't get is: if no residue is left in the soil, what about
when
the roots of the weeds start to break down wont they release chemicals,
which will be then taken up by whats ever growing?
the trouble is I've got about 450 square meters to clear and its taken
about
an hour to do one properly
and now I'm dreaming of roots

No, because it will be released into the soil, where it will be broken
down by bacteria. Apparently, some breakdown products disappear very
slowly from the anaerobic sludge at the bottom of ponds, but garden
soil has a very different (and much more vigorous) collection of
microorganisms.

I'd thought there was some research suggesting it doesn't break down in
soil quite as thoroughly/quickly as was originally believed? Or is that
more a concern where fields of GM-HT crops are resulting in higher
usage?

Surely if it does not break down pretty smartly, the plants surrounding the
targeted weed would die as well? I have never noticed an effect of this
kind.

[Franz Heymann]

In article ,
"Franz Heymann" writes:
|
| I'd thought there was some research suggesting it doesn't break down in
| soil quite as thoroughly/quickly as was originally believed? Or is that
| more a concern where fields of GM-HT crops are resulting in higher
| usage?
|
| Surely if it does not break down pretty smartly, the plants surrounding the
| targeted weed would die as well? I have never noticed an effect of this
| kind.

It breaks down fast; the research that I saw indicated that the problem
was that not all of its breakdown products do.


Regards,
Nick Maclaren.

Nick Maclaren wrote:

In article ,
"Franz Heymann" writes:
|
| I'd thought there was some research suggesting it doesn't break down in
| soil quite as thoroughly/quickly as was originally believed? Or is that
| more a concern where fields of GM-HT crops are resulting in higher
| usage?
|
| Surely if it does not break down pretty smartly, the plants surrounding the
| targeted weed would die as well? I have never noticed an effect of this
| kind.

It breaks down fast; the research that I saw indicated that the problem
was that not all of its breakdown products do.

Yes. The effects are likely to be long-term, altering the soil fauna and
flora. This could eventually affect the plants we see, but it might take
a while.

regards
sarah


--
Think of it as evolution in action.

(Nick Maclaren) wrote in message ...
In article ,
(sw) writes:
|
| No, because it will be released into the soil, where it will be broken
| down by bacteria. Apparently, some breakdown products disappear very
| slowly from the anaerobic sludge at the bottom of ponds, but garden
| soil has a very different (and much more vigorous) collection of
| microorganisms.
|
| I'd thought there was some research suggesting it doesn't break down in
| soil quite as thoroughly/quickly as was originally believed? Or is that
| more a concern where fields of GM-HT crops are resulting in higher
| usage?

The research I have seen was mainly to do with anaerobic sludge.

I believe that your statement is correct in general, but the
original claim was "completely within days" and the current one
is more like "completely, eventually, but with timescale of some
months". However, I have seen only indirect reports on the latter.


Regards,
Nick Maclaren.

The usual figures you see quoted are a half life of 60 days. This can vary.
with a half life of 60 days six months later 10% or so is still around.

Incidentally the other half truth is that it is destroyed on contact will soil.
It isn't it can get bound up b ut not in all soil types.

--
Neil Jones- http://www.butterflyguy.com/
"At some point I had to stand up and be counted. Who speaks for the
butterflies?" Andrew Lees - The quotation on his memorial at Crymlyn
Bog National Nature Reserve

In article ,
(Neil Jones) writes:
|
| I believe that your statement is correct in general, but the
| original claim was "completely within days" and the current one
| is more like "completely, eventually, but with timescale of some
| months". However, I have seen only indirect reports on the latter.
|
| The usual figures you see quoted are a half life of 60 days. This can vary.
| with a half life of 60 days six months later 10% or so is still around.
|
| Incidentally the other half truth is that it is destroyed on contact will soil.
| It isn't it can get bound up b ut not in all soil types.

I am pretty sure that you have confused paraquat and glyphosate;
that is certainly true of the former, but I think that the latter
is at least partially broken down by bacteria.


Regards,
Nick Maclaren.

I believe the claim is that it "becomes inactive" not "breaks down" in a
given number of days.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"Neil Jones" wrote in message
m...

[snip]

The usual figures you see quoted are a half life of 60 days. This can
vary.
with a half life of 60 days six months later 10% or so is still around.

I presume you are talking bout the half-life of the daughter products into
which the original glyphosate decayed. Are there any results which indicate
what sort of a hazard these daughter products might be to which forms of
life?

If the original glyphosate itself took so long to decay, there would not be
much by way of growth left in my garden.

Incidentally the other half truth is that it is destroyed on contact will
soil.
It isn't it can get bound up b ut not in all soil types.

[Franz Heymann]

"David Hill" wrote in message
...
I believe the claim is that it "becomes inactive" not "breaks down" in a
given number of days.

To become inactive, either its chemical composition must have been altered,
in which case it has been "broken down", or it must have become bound so
tightly to one or another soil component as to render it inaccessible to
roots. Which is the correct interpretation?

[Franz Heymann]