Killing vegetation with ammonium sulphamate

[Chris Hogg]

Down one side of the garden we have a long Cornish wall (stone faced,
earth and rubble core), the top of which is presently a rough mixture
of tussocky grass, ivy, montbretia and brambles. The plan is to kill
off this vegetation and plant a fuchsia hedge (F. magellanica). So
far, I've strimmed it right down, and I have in mind to water it with
ammonium sulphamate (AS, aka Root-Out etc.) using a dribble-bar, with
the expectation that this will be absorbed both through the top growth
(what's left of it) and through the roots, as I believe AS persists
for a while in the soil. In the spring, I intend to plant the hedge,
currently at the cuttings-just-taken stage.

A couple of questions. How long does AS persist in the soil; i.e. will
it all have broken down by the spring? Is there a better way of
killing off the vegetation, such as e.g. SBK or Jeyes Fluid? I don't
want to spray, partly because of the potential problem of drift, and
partly because having strimmed it, the amount of top-growth left to
absorb the chemicals is now much reduced. Root absorption would seem a
more certain way to go, at least in part, as some of the grass is very
persistent and I have had difficulty eradicating it elsewhere even
with glyphosate.

[DaveP]

Post by Chris Hogg
Down one side of the garden we have a long Cornish wall (stone faced,
earth and rubble core), the top of which is presently a rough mixture
of tussocky grass, ivy, montbretia and brambles. The plan is to kill
off this vegetation and plant a fuchsia hedge (F. magellanica). So
far, I've strimmed it right down, and I have in mind to water it with
ammonium sulphamate (AS, aka Root-Out etc.) using a dribble-bar, with
the expectation that this will be absorbed both through the top growth
(what's left of it) and through the roots, as I believe AS persists
for a while in the soil. In the spring, I intend to plant the hedge,
currently at the cuttings-just-taken stage.
A couple of questions. How long does AS persist in the soil; i.e. will
it all have broken down by the spring? Is there a better way of
killing off the vegetation, such as e.g. SBK or Jeyes Fluid? I don't
want to spray, partly because of the potential problem of drift, and
partly because having strimmed it, the amount of top-growth left to
absorb the chemicals is now much reduced. Root absorption would seem a
more certain way to go, at least in part, as some of the grass is very
persistent and I have had difficulty eradicating it elsewhere even
with glyphosate.

Ammonium sulphamate is contact herbicide Chris and only kills the
parts of a plant that it hits, so deep rooted, persistent weeds tend
to survive unless very heavy applicatons are given. It is broken down
by microbes in the soil over 6-8 weeks during warm weather and
exponentially longer as the temperatures reduce. It is also more
persistent in drier soils. As a herbicide, it is virtually non-toxic
to birds, fish and most mammals and is non carcinogenic to humans.

Your weed problem would be best dealt with over several months using a
systemic herbicide such as glyphosate. Late season applications are
rarely effective and are best carried out when the plants are in full
growth prior to flowering. Unfortunately now is not a good time to
eradicate any weeds using chemical means. Many grasses fail to
respond to glyphosate because beading and rapid run-off due to fine
hairs, prevents sufficient chemical to remain on the foliage. Using a
'wetting agent' such as soft soap greatly increases the adhesion of
the mix to the leaves. In domestic situations, 5ml.(1 teaspoon) of
washing up liquid added to the mixture will ensure that grass and waxy
leaved plants are better coated and therefore more of the herbicide
will be absorbed.

[Chris Hogg]

On Sun, 27 Sep 2009 10:03:15 -0700 (PDT), DaveP

Post by DaveP
Ammonium sulphamate is contact herbicide Chris and only kills the
parts of a plant that it hits, so deep rooted, persistent weeds tend
to survive unless very heavy applicatons are given. It is broken down
by microbes in the soil over 6-8 weeks during warm weather and
exponentially longer as the temperatures reduce. It is also more
persistent in drier soils. As a herbicide, it is virtually non-toxic
to birds, fish and most mammals and is non carcinogenic to humans.
Your weed problem would be best dealt with over several months using a
systemic herbicide such as glyphosate. Late season applications are
rarely effective and are best carried out when the plants are in full
growth prior to flowering. Unfortunately now is not a good time to
eradicate any weeds using chemical means. Many grasses fail to
respond to glyphosate because beading and rapid run-off due to fine
hairs, prevents sufficient chemical to remain on the foliage. Using a
'wetting agent' such as soft soap greatly increases the adhesion of
the mix to the leaves. In domestic situations, 5ml.(1 teaspoon) of
washing up liquid added to the mixture will ensure that grass and waxy
leaved plants are better coated and therefore more of the herbicide
will be absorbed.

Thanks for that, Dave. I'll try treating it this autumn while things
are still growing, and then give it some more treatment next spring if
necessary.