Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Herbicidal Composition and Adjuvant
The present invention relates to a herbicidal composition and in particular a
composition containing the herbicide glyphosate.
N-phosphonomethylglycine, known by its common name glyphosate, is a well
known broad spectrum herbicide which is widely used in domestic and broadacre
weed control. Glyphosate is a water insoluble acid and is therefore formulated
as
a water soluble salt, generally the isopropylamine salt.
Glyphosate is sold and used in a range of formulation types. The manufacturers
of glyphosate generally prepare it for transport and shipping as an aqueous
concentrate from which commercial products can readily be prepared by dilution
and in some cases the addition of additives.
Glyphosate may be formulated for sale as an aqueous concentrate which is
diluted by the end user prior to application. Concentrates may be packaged
with
surfactants and may be used with adjuvants which are mixed with the herbicide
in
a spray tank before use. Glyphosate is also sold to domestic markets as a
dilute
solution packaged with a spray applicator ready for direct application to
weeds.
Water soluble granules or powders are also available which contain a
glyphosate
salt and generally also a surfactant. These dry formulations are dissolved in
water by the end user before application.
Despite the versatility of glyphosate it tends to be less stable in solution
particularly concentrated solutions at low temperature and the high viscosity
of
concentrated solutions makes them difficult to pump and handle. There is a
need
for a glyphosate composition which is stable and easy to handle in a wide
range
of formulations.
Glyphosate products are frequently sprayed in conjunction with other
pesticides.
Although this can greatly reduce the cost of application incompatibility
between
glyphosate and the second pesticide can be an issue.
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We have now found that by mixing the isopropylamine salt of glyphosate with
the
ammonium salt of glyphosate, particularly in certain ratios, compositions are
stable at a wide range of concentrations. For example, the viscosity of
aqueous
solutions is reduced allowing the composition to be more easily dispensed or
allowing the concentration to be significantly increased while remaining
stable.
This finding was surprising as the ammonium salt of glyphosate is much less
soluble than the isopropylamine salt. The compositions of the invention also
generally exhibit good compatibility with other pesticides.
In accordance with the invention we provide a glyphosate composition including
the monoisopropylamine salt of glyphosate and the ammonium salt of glyphosate.
The ratio of said monoisopropylamine salt to said ammonium salt is typically
in
the range of from 80:20 to 97:3 based on the weight of glyphosate in the acid
form. In this ratio of salt the composition is surprisingly versatile allowing
extremely high concentrations to be handled more easily and with enhanced
stability.
In a particularly preferred embodiment of the invention the weight ratio of
said
monoisopropylamine salt to said ammonium salt is in the range of 85:15 to 95:5
based on the weight of glyphosate in the acid form.
The glyphosate composition of the invention may use glyphosate at a wide range
of concentrations. For example the composition may have a high concentration
of 600g/L, based on the weight of glyphosate in the acid form, or more such as
may be used for transport and shipping, it may be a concentrate of the type to
be
diluted prior to use or it may be a dilute composition prepared from the
concentrate or of the type sold in spray packs for domestic use.
It is desirable to sell and transport glyphosate as a high concentration
aqueous
solution however the useful concentration of conventional compositions is
limited
by viscosity of the formulation and its solution stability. Conventional
glyphosate
compositions become increasingly viscous in aqueous solution at concentrations
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above 300g/L (based on the acid form) and particularly from about 360g/L with
the result that at high concentrations they cannot as readily be dispensed by
the
end user. The pumps used by farmers to dispense herbicides do not readily
allow
delivery of compositions containing over 490g/L glyphosate. At high
concentrations glyphosate is also less stable in solution, particularly at low
temperatures.
The glyphosate concentrate compositions of the invention will typically
include at
least 300g/L of glyphosate. The compositions of the invention are particularly
advantageous when they include at least 360g/L glyphosate based on acid form
and preferably they include at least 450g/L. Even more preferably the
concentration is at least 490g/L and most preferably the glyphosate
concentration
is at least 500g/L. We have found that concentration of up to 540g/L or more
may
be formed with a viscosity allowing easy dispensing by the container pump
systems used by farmers. Further the composition is generally stable even at
low
temperatures for example at 5°C.
Manufacturing concentrates may be prepared with concentrations of as high as
620g/L or more. Although concentrated compositions of at least 360g/L
glyphosate are preferred the composition of the invention may be in the form
of a
diluted composition if desired. The concentration will preferably be at least
3.6g/L
For example it may be in the form of a dilute formulation prepared from a
concentrate before application or it may be a dilute solution of the type
packaged
for the domestic market.
The composition of the invention may and typically will contain other
additives.
For example the composition may include a surfactant component. The surfactant
component may include one or more surfactants and is preferably present in an
amount of up to 20% by weight of the total composition. In cases where the
surfactant is present at the upper end of this range the glyphosate
concentration
will be relatively low. More preferably the surfactant is present in an amount
of up
to 5% by weight of the total composition. At such surfactant concentrations
higher amounts of glyphosate may be used to provide at least 500g/L
glyphosate.
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Examples of surfactants which may be useful include alkanolamides, betaine
derivatives, ethoxylated propoxylated block copolymers, glycerol esters,
glycol
esters, imidazolines and imidazoline derivatives, lanolin derivatives,
lecithin
derivatives, tertiary or quaternary polyoxyalkylene alkylamines,
polyoxyalkylene
and non-polyoxyalkylene alkylamine oxides, polyoxyalkylene alkylethers,
polyoxyalkylene alkylarylethers, polyoxyalkylene alkylesters, alkoxylated and
non-
alkoxylated sorbitan esters, alkyl glycosides, alkyl polyglycosides, sucrose
esters,
sucrose glycerides, alkyl sulphates or phosphates, olefin sulfonates,
alkylaryl
sulfonates, polyoxyalkylene alkylether sulphates or phosphates, sulfosuccinate
derivatives, sulfosuccinamates, taurates, sulphates and sulfonates of oils,
fatty
acids, alcohols, alkoxylated alcohols, fatty esters and aromatic derivatives
and
mixtures thereof.
We have found the properties of the composition are particularly useful when
the
surfactant includes a phosphate ester, particularly an ethoxylated alcohol
phosphate ester which may be in the form of a salt such as the ammonium or
alkylamine salt such as the monoisopropylamine salt. It is particularly
preferred
that the surfactant includes the ammonium salt of the ethoxylated alcohol
phosphate ester.
It is often desirable to use other herbicides in combination with glyphosate.
In
some cases these other herbicides can be mixed with the glyphosate composition
and additives shortly before application. Dinitroanilines are one of the most
commercially successful classes of herbicides. In particular, trifluralin is
widely
used in pre-sowing application to soil in many important crops. It is
effective
against both grassy weeds and broad-leave weeds. Herbicides of the triazine
family, particularly atrazine, are also used at the time of sowing crops,
particularly
canola.
In order to kill the maximum number of weeds the timing for application of
glyphosate needs to be left until shortly before sowing. This also coincides
with
the optimal timing for dinitroanilines and triazines. If glyphosate and
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dinitroanilines or triazines could be effectively applied together this has
the
potential to allow better knockdown. It would also allow farmers to sow a crop
at
the optimal time to maximise yield and reduce competition from weeds. Tank
mixing of the herbicides would reduce the labour and cost associated with
5 separate applications which are currently required.
Existing formulations of glyphosate are generally incompatible with
dinitroanilines
and triazines. For example mixture with trifluralin or atrazine can result in
phase
separation when the herbicides are combined. Also their combined use has been
found to seriously reduce the efficacy of the compositions.
We have found that the compositions of the invention exhibit improved
compatibility. In particular when the ammonium salt of an ethoxylated alcohol
phosphate ester is used as the surfactant in the compositions of the invention
the
formulation is compatible with dinitroanilines or triazines and mixtures of
these
herbicides with glyphosate do not generally suffer loss of efficacy to the
same
extent as conventional formulations. Indeed there is a significant improvement
in
efficacy when compared with combinations of the presently available herbicide
compositions at corresponding concentrations.
Accordingly in a preferred embodiment of the invention we provide a glyphosate
formulation including the monoisopropylamine salt of glyphosate and the
ammonium salt of glyphosate wherein the ratio of said monoisopropylamine salt
and ammonium salt is in the range from 80:20 to 97:3 (preferably 85:15 to
95:5)
and therein the formulation includes a surfactant including the ammonium salt
of
an ethoxylated alcohol phosphate ester. The ethoxylated alcohol phosphate
ester is preferably present in an amount of up to 5% by weight of the
composition
and most preferably from 0.5 to 5% by weight of the total composition.
The composition of the invention may be used as a stand alone product by
diluting it with water to the required glyphosate concentration. It is
desirable in
many circumstances to use the herbicide composition in combination with an
adjuvant. When the herbicide composition is to be used with other herbicides
or
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with hard diluting water (over 1000 ppm) then use of an adjuvant is
particularly
preferred. Suitable adjuvants for use with glyphosate are known in the
industry
and they may be used if desired.
Suitable adjuvants include equivalently acceptable inorganic salts,
dispersants,
wetters and antifoam agents. Examples of acceptable inorganic salts include
ammonium sulphate, ammonium nitrate, potassium phosphate, tetrapotassium
pyrophosphate, sodium bisulphate, sodium sulphate, ammonium bicarbonate.
Ammonium sulphate is particularly preferred.
Examples of dispersants and wetters include the surfactants referred to above,
however preferred dispersants include long aliphatic quaternary ammonium
compounds, aliphatic amines, alkylpolysaccharides and ethoxylated phosphates.
Ethoxylated fatty amine surfactants such as soya amine ethoxylate and tallow
amine ethoxylate, alkylpolysaccharides and ethoxylated alcohol phosphate ester
or mixtures, of two or more thereof, or with the above examples of surfactants
are
particularly useful.
The adjuvant may if desired contain crop oils such as paraffinic oils,
vegetable
oils or vegetable oil derivatives.
We have found that certain types of adjuvant components in combination provide
compatibility with other herbicides such as triazine and dinitroanilines and a
level
of activity which is not readily obtained with existing adjuvants.
Accordingly in a further aspect the invention provides an adjuvant composition
for
use with glyphosate herbicide compositions the adjuvant including:
ammonium sulphate, an alkylammonium sulphate or mixture thereof;
a surfactant component including an ammonium salt of an ethoxylated
alcohol phosphate ester and
an amphoteric surfactant.
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The alkylammonium sulphate when present may be a mono-, di- or trialkyl-
ammonium sulphate. The alkyl group or groups preferably contain up to six
carbon atoms, more preferably up to 4 carbon atoms and most preferably are
isopropyl. Ammonium sulphate is preferably present.
The amphoteric surfactant is preferably a phospholipid with an acidic buffer,
particularly propionic acid .
The preferred concentration of components in the adjuvant are as follows:
from 5 to 30% w/w of ammonium sulphate alkylammonium sulphate or
mixture thereof;
from 0 to 25% w/w, preferably from 0.5 to 25% w/w of ammonium salt of an
ethoxylated alcohol phosphate ester and;
from 0.5 to 10% w/w of amphoteric surfactant which is preferably a
phospholipid.
The adjuvant of the invention may be used with the glyphosate composition of
the
invention or it may be used with other glyphosate compositions such as those
which are commercially available from numerous sources. The adjuvant
composition of the invention will generally be mixed with a glyphosate
composition shortly before use. The composition will normally be mixed in the
spray tank however it is preferred that at least a portion of the adjuvant to
be used
is added to the spray tank prior to the glyphosate. Preferably all of the
adjuvant
component to be used will be added to the spray tank prior to addition of the
glyphosate composition.
The present invention will now be more fully described with reference to the
following examples. It should be understood, however, that the description
following is illustrative only and should not be taken in any way as a
restriction on
the generality of the invention described above. Where the concentration of
glyphosate is expressed in grams per litre (g/L) it is understood that this
refers to
grams of glyphosate as the acid form per litre of composition.
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Example 1
A glyphosate composition in accordance with the invention was prepared by
combining the following components in the relative quantities specified:
RAW MATERIAE.~ ~ ~ ~ G~uant~ty~
K~l. 3 ;~..
*Glyphosate Acid (Wetcake) 0.6287
2-Propanamine 100% w/w 0.1864
Ammonia (28% w/w) 0.0213
GERONOL CF/AR 0.0266
LUCONYL Green FK872 0.001
Process Water 0.3710
Specific Gravity 1.2350
*The glyphosate acid wetcake contained approximately 86% w/w glyphosate
based on glyphosate acid (11 % w/w water). The purity of the glyphosate was
96.5% on a dry basis.
The composition, which contains 540g/L glyphosate could readily be delivered
using standard pumps used by farmers and was stable in solution at
temperatures of 5°C for extended periods.
GERONOL CF/AR surfactant sold by Rhodia is the 2-propanamine salt of
ethoxylated alcohol phosphate ester.
Example 2
An adjuvant formulation for use with a glyphosate composition was prepared by
combining the following components in the relative quantities specified:
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RAW MATER~'A~~~~ ~ ~ ;t~U~,WT1'T~
h ' ~' ~~
K~CI
~a <; ~~~.~r, ~ ~,3~,~....~,
~ w. ,
~ ~~~ ~~
Ammonium Sulphate 0.2550
RHODOFAC ARB-70 0.1786
Ammonia (28%w/w) 0.0510
Li-700 0.0455
Process Water 0.6320
Specific Gravity 1.162
RHODOFAC ARB-70 sold by Rhodia is an ethoxylated alcohol phosphate ester
and forms the ammonium salt in solution.
Li-700 from Loveland Industries Inc, U.S.A. is a mixture of soyal
phospholipids and
propionic acid.
The combination of components in the adjuvant composition generally allows for
better physical compatibility and improved efficacy even in hard water.
Example 3
The performance of the composition according to the present invention
comprising the glyphosate composition of Example 1 and the adjuvant
formulation of Example 2, was compared with a leading commercial glyphosate
formulation containing 490g/L glyphosate (based on glyphosate acid) in the
form
of the isopropylamine salt (Comparative example).
The results are shown in the attached drawings.
Referring to the drawings:
Figure 1 is a graph comparing the viscosity of the glyphosate formulation of
the invention with a leading 490g/L glyphosate formulation.
Figure 2 is a bar chart comparing the low use rate efficiency of a 1:1
mixture (by volume) of the composition/adjuvant formulation of Example
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1/Example 2 with the comparative glyphosate/adjuvant combination (Comparative
example) - in the recommended mixing ratio - at the rate of grams of active
ingredient per hectare.
5 Figure 3 is a bar chart comparing the weed control performance of the
composition of the Example 1 when used with the adjuvant of Example 2 in a 1:1
volume ratio with the composition of Comparative example when used with the
recommended surfactant adjuvant.
10 Figure 4 is a bar chart comparing the efficiency obtained by the crop
performance of the glyphosate/adjuvant combination of Examples 1 and 2 (1:1
volumetric ratio) with the composition of Comparative example when used
together with TRIFLUR trifluralin formulation.
Figure 5 is a bar chart comparing the performance of the
glyphosate/adjuvant combination of Examples 1 and Example 2 (1:1 volumetric
ratio) with the composition of the Comparative example, when each are used
with
NUTRAZINE brand atrazine formulation.
Referring to Figure 1 it can be seen that the viscosity of the composition of
the
invention is significantly less than the prior art formulation despite
containing
540g/L compared with the prior art containing 490g/L. The dual salt
composition
of the invention gives a viscosity which is typically 30% less than the prior
art high
loading compositions which merely contain 490g/L glyphosate acid
Referring to Figure 2 it can be seen that despite lower use rates placing more
pressure on the surfactant system the composition/adjuvant combination of the
invention performs successfully even at low rates. We found higher efficacy
thus
prior art formulations of 490g/L glyphosate at equivalent low usage rates
(gai/ha=
grams active ingredient per hectare). As shown in Figure 3 we also found good
activity on broadleaf weeds such as cape weed or clover at equivalent rates.
This
is a weakness of many prior art formulations.
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Glyphosate products are frequently sprayed in conjunction with other
pesticides
but incompatibility with other pesticides is sometimes an important issue
which
can arise from physical effects within the spray tank or biological effects.
Biological incompatibility (antagonism) may result from interactions between
herbicides resulting in poorer weed control than when the herbicides are
separately applied. Figures 4 and 5 show that the glyphosate composition of
the
invention exhibits a high compatibility rate when compared with a high rate
glyphosate composition. Figure 4 compares the invention with the prior art
composition when each are used with a commercial Trifluralin composition.
Figure 5 compares composition of the invention with the prior art composition
when used with commercial atrazine formulation.
It is to be understood that the invention described hereinabove is susceptible
to
variations, modifications and/or additions other than those specifically
described
and that the invention includes all such variations, modifications and/or
additions
which fall within the spirit and scope of the above description.
