Note: Descriptions are shown in the official language in which they were submitted.
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Low volatility herbicidal compositions
The present invention relates to low volatility herbicidal compositions
comprising at least one
auxin herbicide and at least one cationic polysaccharide derivative.
The invention further relates to methods for preparing and using such low
volatility herbicidal
compositions, including methods of reducing the volatility of an auxin
herbicide and methods
of reducing off-site movement of an auxin herbicide.
Auxin herbicides are a well-known class of herbicides used to kill weeds by
inducing
hormonal effects on sprayed plants. They are thus commonly used to control
auxin-
susceptible plant growth. Typical representatives of auxin herbicides
include 2,4-D
(2,4-dichlorophenoxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic
acid).
Drift, but most importantly volatility, are problems frequently faced when
using this class of
herbicides.
Spray drift is defined by the Environmental Protection Agency as the movement
of pesticide
dust or droplets through the air at the time of application or soon
thereafter, to any site other
than the area intended.
As for volatilization, it occurs when pesticide surface residues change from a
solid or liquid to
a gas or vapor after an application of a pesticide has occurred. Once
airborne, volatile
pesticides can move long distances off site (and in particular longer
distances compared to
spray drift).
Non-target plant damage associated with auxin herbicide volatilization is a
major concern for
crop growers nowadays. As a matter of fact, unintentional application of auxin
herbicides to
a sensitive plant generally causes severe injury, loss of yield, and even
death of the non-
target plants.
This is the reason why there is an increasing demand today for low volatility
auxin herbicide
compositions.
Impact of the counter-ion has already been investigated and it has been
demonstrated, for
instance, that the diglycolamine salt of dicamba exhibits a lower volatility
than the
dimethylamine salt of dicamba. Also, the addition of specific polybasic
polymers to dicamba
formulations has been reported.
An object of the present invention is to provide an adjuvant which is useful
for reducing the
volatility and off-target movement of auxin herbicides.
Another object of the present invention is to provide auxin herbicide
compositions having
reduced volatility relative to currently available compositions, and
preferably reduced-
volatility compositions that exhibit no significant reduction in herbicidal
effectiveness relative
to currently available compositions.
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It has been discovered unexpectedly that the addition of a sufficient amount
of a
polysaccharide derivative as defined according to the invention to an auxin
herbicide
compositions results in a reduced auxin herbicide volatility upon application
relative to an
otherwise identical composition lacking the polysaccharide derivative as
defined according to
the invention.
Specifically, the compositions of the invention comprise, in addition to the
auxin herbicide, at
least one polysaccharide derivative, wherein said polysaccharide derivative is
a cationic
polysaccharide derivative, in an amount sufficient to reduce the volatility of
the auxin
herbicide relative to an otherwise identical composition lacking said
polysaccharide
derivative.
In one aspect, the present invention provides a method of reducing the
volatility of an auxin
herbicide, the method comprising the step of contacting the auxin herbicide
with a volatility-
lowering effective amount of at least one cationic polysaccharide derivative,
thereby reducing
the volatility of the auxin herbicide.
In another aspect, the present invention provides a method of reducing off-
site movement of
an auxin herbicide following application to the foliage of auxin-susceptible
plants of a
herbicidal mixture comprising an auxin herbicide, the method comprising :
i/ preparing an herbicidal application mixture comprising an auxin herbicide;
at least one
cationic polysaccharide derivative; and a solvent, for instance water; and
ii/ applying the herbicidal mixture to the foliage of the auxin-susceptible
plants.
In another aspect, the present invention provides an herbicidal composition
comprising :
- at least one auxin herbicide, and
- at least one cationic polysaccharide derivative.
In another aspect, the present invention provides a process for preparing a
diluted auxin
herbicide spray formulation exhibiting reduced off-site movement of said auxin
herbicide
comprising introducing a cationic polysaccharide derivative to said diluted
agrochemical
spray formulation.
In another aspect, the present invention provides a method for treating an
agricultural field
comprising spraying the field with such a diluted auxin herbicide spray
formulation.
Advantageously, it is believed that the compositions of the present invention
provide
enhanced protection from off-target crop injury while maintaining comparable
herbicidal
efficacy on auxin-susceptible plants located in the target area.
The auxin-susceptible plants can be weeds or crop plants. Crop plants include,
for example,
vegetable crops, grain crops, flowers, and root crops. Crop plants further
encompass
hybrids, inbreds, and transgenic or genetically modified plants.
In particular, it is believed that the addition of the polysaccharide
derivative as defined
according to the invention, preferably at the loading values discussed below,
to the herbicidal
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compositions of the present invention effectively reduces auxin herbicide
volatility and the
associated crop injury without significantly reducing auxin herbicide
effectiveness.
Impact on the auxin herbicide volatility can be measured by conventional means
known to
those skilled in the art.
.. For instance, volatilization of an auxin herbicide can be assessed as
follows : an auxin
herbicide composition is heated, causing the auxin herbicide to volatilize
from said
composition into the gas phase. Weight of residual auxin herbicide composition
is recorded
against time (through thermogravimetric analyses), allowing indirect
measurement of
volatilization of the auxin herbicide.
AUXIN HERBICIDE
The term "auxin herbicide" refers to a herbicide that functions as a mimic of
an auxin plant
growth hormone, thereby affecting plant growth regulation. Examples of auxin
herbicides
that are suitable for use in the herbicidal compositions of the present
invention include,
.. without limitation, benzoic acid herbicides, phenoxy herbicides, pyridine
carboxylic acid
herbicides, pyridine oxy herbicides, pyrimidine carboxy herbicides, quinoline
carboxylic acid
herbicides, and benzothiazole herbicides.
According to anyone of the invention embodiments, the auxin herbicide is
selected in the
group consisting of 2,4-D (2,4-dichlorophenoxyacetic acid), 2,4-DB (4-(2,4-
dichlorophenoxy)butanoic acid), dichloroprop (2-(2,4-dichlorophenoxy)propanoic
acid),
MCPA ((4-chloro-2-methylphenoxy)acetic acid), MCP B
(4-(4-chloro-2-
methylphenoxy)butanoic acid), aminopyralid (4-amino-3,6-dichloro-2-
pyridinecarboxylic acid),
clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), fluoroxypyr ([(4-amino-
3,5-dichloro-6-
fluoro-2-pyridinyl)oxy]acetic acid), triclopyr ([(3,5,6-trichloro-2-
pyridinyl)oxy]acetic acid),
diclopyr, mecoprop (2-(4-chloro-2-methylphenoxy)propanoic acid) and mecoprop-
P, dicamba
(3,6-dichloro-2-methoxybenzoic acid), picloram (4-amino-3,5,6-trichloro-2-
pyridinecarboxylic
acid), quinclorac (3,7-dichloro-8-quinolinecarboxylic acid),
aminocyclopyrachlor (6-amino-5-
chloro-2-cyclopropy1-4-pyrimidinecarboxylic acid), agriculturally acceptable
salts of any of
these herbicides, racemic mixtures and resolved isomers thereof, and mixtures
thereof.
According to anyone of the invention embodiments, the auxin herbicide is
dicamba, or an
agriculturally acceptable salt or ester thereof, for instance dicamba sodium
salt, dicamba
potassium salt, dicamba monoethanolamine salt, dicamba diethanolamine salt,
dicamba
isopropylamine salt, dicamba diglycolamine salt,
dicamba N, N-bis-(3-
am inopropyl)methylam ine salt or dicamba dimethylamine salt.
According to another one of the invention embodiments, the herbicidal
composition
comprises at least 2,4-D, or an agriculturally acceptable salt or ester
thereof.
For instance, a herbicidal composition of the invention may comprise a 2,4-D
salt selected in
the group consisting of : the choline, dimethylamine, and isopropylamine
salts, and
combinations thereof.
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For instance, a herbicidal composition of the invention may comprise a 2,4-D
ester selected
in the group consisting of : the methyl, ethyl, propyl, butyl (2,4-DB), and
isooctyl esters, and
combinations thereof.
POLYSACCHARIDE DERIVATIVE
Suitable, non !imitative, examples of polysaccharide polymers include, for
example,
galactomannans, chitosan, pectin, alginate, hyaluronic acid, agar, xanthan,
dextrin, starch,
cellulose, amylose, amylopectin, alternan, gellan, levan, mutan, dextran,
pullulan, fructan,
gum arabic, carrageenan, glycogen, glycosaminoglycans, murein, xyloglucans and
bacterial
capsular polysaccharides.
In one embodiment, the polysaccharide of the invention include, for example,
galactomannans such as guars, including guar derivatives, xanthans,
polyfructoses such as
levan, starches, including starch derivatives, such as amylopectin,
xyloglucans such as
tamarind gum and tamarind gum derivatives such as hydroxypropyl tamarind gum,
and
cellulose, including cellulose derivatives, such as methylcellulose,
ethylcellulose,
carboxymethylcellu lose, hydroxyethylcellu lose, cellulose acetate, cellulose
acetate butyrate,
and cellulose acetate propionate.
Galactomannans are polysaccharides consisting mainly of the monosaccharides
mannose
and galactose. The mannose-elements form a chain consisting of many hundreds
of (1,4)-f3-
D-mannopyranosyl-residues, with 1,6 linked-D-galactopyranosyl-residues at
varying
distances, dependent on the plant of origin. Naturally occurring
galactomannans are
available from numerous sources, including guar gum, guar splits, locust bean
gum and tara
gum, flame tree gum and cassia gum.
Additionally, galactomannans may also be obtained by classical synthetic
routes or may be
obtained by chemical modification of naturally occurring galactomannans.
Guar gum refers to the mucilage found in the seed of the leguminous plant
Cyamopsis
tetragonolobus. The water soluble fraction (85%) is called "guaran," which
consists of linear
chains of (1,4)-.6-D mannopyranosyl units-with a-D-galactopyranosyl units
attached by (1,6)
linkages. The ratio of D-galactose to D-mannose in guaran is about 1:2. Guar
gum typically
.. has a weight average molecular weight of between 2,000,000 and 5,000,000
g/mol. Guars
having a reduced molecular weight, such as for example, from about 50,000 to
about
2,000,000 g/mol are also known.
Guar seeds are composed of a pair of tough, non-brittle endosperm sections,
hereafter
referred to as "guar splits," between which is sandwiched the brittle embryo
(germ). After
dehulling, the seeds are split, the germ (43-47% of the seed) is removed by
screening, and
the splits are ground. The ground splits are reported to contain about 78-
82%
galactomannan polysaccharide and minor amounts of some proteinaceous material,
inorganic non-surfactant salts, water-insoluble gum, and cell membranes, as
well as some
residual seedcoat and embryo.
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Locust bean gum or carob bean gum is the refined endosperm of the seed of the
carob tree,
Ceratonia siliqua. The ratio of galactose to mannose for this type of gum is
about 1:4.
Locust bean gum is commercially available.
Tara gum is derived from the refined seed gum of the tara tree. The ratio of
galactose to
5 mannose is about 1:3. Tara gum is commercially available.
Other galactomannans of interest are the modified galactomannans, including
derivatized
guar polymers, such as carboxymethyl guar, carboxymethylhydroxypropyl guar,
cationic
guar, cationic hydroxyalkyl guar, including cationic hydroxyethyl guar,
cationic hydroxypropyl
guar, cationic hydroxybutyl guar and cationic higher hydroxylalkyl guars,
hydroxyalkyl guar,
including hydroxyethyl guar, hydroxypropyl guar, hydroxybutyl guar and higher
hydroxylalkyl
guars, carboxylalkyl guars, including carboxymethyl guar, carboxylpropyl guar,
carboxybutyl
guar, and higher carboxyalkyl guars, the hydroxyethylated, hydroxypropylated
and
carboxymethylated derivative of guaran, the hydroxethylated and
carboxymethylated
derivatives of carubin, and the hydroxypropylated and carboxymethylated
derivatives of
cassia-gum.
Xanthans of interest are xanthan gum and xanthan gel. Xanthan gum is a
polysaccharide
gum produced by Xathomonas campestris and contains D-glucose, D-mannose, D-
glucuronic acid as the main hexose units, also contains pyruvate acid, and is
partially
acetylated.
Levan is a polyfructose comprising 5-membered rings linked through 13-2,6
bonds, with
branching through 13-2,1 bonds. Levan exhibits a glass transition temperature
of 138 C and
is available in particulate form. At a molecular weight of 1-2 million, the
diameter of the
densely-packed spherulitic particles is about 85 nm.
Tamarind (Tamahndus Indica) is a leguminous evergreen tall tree produced in
the tropics.
Tamarind gum (tamarind powder or tamarind kernel powder), a xyloglucan
polysaccharide, is
obtained by extracting and purifying the seed powders, obtained by grinding
the seeds of
tamarind. The polysaccharide molecule of the tamarind gum consists of a main
linear chain
of poly-glucose bearing xylose and galactoxylose substituents.
Modified celluloses are celluloses containing at least one functional group,
such as a hydroxy
group, hydroxycarboxyl group, or hydroxyalkyl group, such as for example,
hydroxymethyl
cellulose, hydroxyethyl celluloses, hydroxypropyl celluloses or hydroxybutyl
celluloses.
Processes for making polysaccharide derivatives are known. In particular,
processes for
making derivatives of guar gum splits are generally known. Typically, guar
splits are reacted
with one or more derivatizing agents under appropriate reaction conditions to
produce a guar
polysaccharide having the desired substituent groups. Suitable derivatizing
reagents are
commercially available and typically contain a reactive functional group, such
as an epoxy
group, a chlorohydrin group, or an ethylenically unsaturated group, and at
least one other
substituent group, such as a cationic, nonionic or anionic substituent group,
or a precursor of
such a substituent group per molecule, wherein substituent group may be linked
to the
reactive functional group of the derivatizing agent by bivalent linking group,
such as an
alkylene or oxyalkylene group. Suitable cationic substituent groups include
primary,
secondary, or tertiary amino groups or quaternary ammonium, sulfonium, or
phosphinium
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groups. Suitable nonionic substituent groups include hydroxyalkyl groups,
such as
hydroxypropyl groups. Suitable anionic groups include carboxyalkyl groups,
such as
carboxymethyl groups. The cationic, nonionic and/ or anionic substituent
groups may be
introduced to the polysaccharide chains via a series of reactions or by
simultaneous
reactions with the respective appropriate derivatizing agents.
The polysaccharide derivative, for instance the guar derivative, may be
treated with a
crosslinking agent, such for example, borax (sodium tetra borate) is commonly
used as a
processing aid in the reaction step of the water-splits process to partially
crosslink the
surface of the guar splits and thereby reduces the amount of water absorbed by
the guar
splits during processing. Other crosslinkers, such as, for example, glyoxal or
titanate
compounds, are known.
In one embodiment, the polysaccharide component of the composition of the
present
invention is a non-derivatized polysaccharide, for instance a non-derivatized
galactomannan
polysaccharide, more typically a non-derivatized guar gum.
In one embodiment, the polysaccharide is a derivatized polysaccharide, for
instance a
derivatized galactomannan polysaccharide that is substituted at one or more
sites of the
polysaccharide with a substituent group that is independently selected for
each site from the
group consisting of cationic substituent groups, nonionic substituent groups,
and anionic
substituent groups.
In one specific embodiment, the polysaccharide derivative of the invention is
a cationic
polysaccharide derivative, that is to say a derivatized polysaccharide that is
substituted at
one or more sites of the polysaccharide with a substituent group that is a
cationic substituent
group.
In one specific embodiment, the polysaccharide derivative of the invention is
a non ionic, for
instance hydroxyalkylated, polysaccharide derivative, that is to say a
derivatized
polysaccharide that is substituted at one or more sites of the polysaccharide
with a
substituent group that is a non ionic, for instance hydroxyalkyl, substituent
group.
In one specific embodiment, the polysaccharide derivative of the invention is
an anionic
polysaccharide derivative, that is to say a derivatized polysaccharide that is
substituted at
one or more sites of the polysaccharide with a substituent group that is an
anionic substituent
group.
In one embodiment, the polysaccharide derivative of the present invention is
derivatized
galactomannan polysaccharide, more typically a derivatized guar.
Suitable derivatized guars include, for example, hydroxypropyl
trimethylammonium guar,
hydroxypropyl lauryldimethylammonium guar, hydroxypropyl
stearyldimethylammonium guar,
hydroxypropyl guar, carboxymethyl guar, guar with hydroxypropyl groups and
hydroxypropyl
trimethylammonium groups, guar with carboxymethyl hydroxypropyl groups and
mixtures
thereof.
In another embodiment, the polysaccharide derivative of the present invention
is derivatized
xyloglucan polysaccharide, more typically a derivatized tamarind.
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Suitable derivatized tamarinds include, for instance, hydroxypropyl tamarind
gum, which may
further contain substituent groups such as carboxyalkyl substituents (e.g.
carboxymethyl or
carboxyethyl) or hydrophobic substituents (e.g. 04-024 linear or branched
alkyl chains),
such as those described in W02016/124467, which is incorporated by reference.
The amount of derivatizing groups in a derivatized polysaccharide polymer may
be
characterized by the degree of substitution of the derivatized polysaccharide
polymer or the
molar substitution of the derivatized polysaccharide polymer.
As used herein, the terminology "degree of substitution" in reference to a
given type of
derivatizing group and a given polysaccharide polymer means the number of the
average
number of such derivatizing groups attached to each monomeric unit of the
polysaccharide
polymer. In one embodiment, the derivatized galactomannan polysaccharide
exhibits a total
degree of substitution ("DST") of from about 0.001 to about 3.0, wherein :
DST is the sum of the DS for cationic substituent groups (UDScationi."), the
DS for
nonionic substituent groups (DSnonionic) and the DS for anionic substituent
groups
("DSanionic"),
DScationic is from 0 to about 3, more typically from about 0.001 to about 2.0,
and even
more typically from about 0.001 to about 1.0,
DSnonionic is from 0 to 3.0, more typically from about 0.001 to about 2.5, and
even more
typically from about 0.001 to about 1.0, and
DSanionic is from 0 to 3.0, more typically from about 0.001 to about 2Ø
DScationic, DSnonionic, and DSanionic may be measured for instance by 1H-NMR.
As used herein, the term "molar substitution" or "ms" refers to the number of
moles of
derivatizing groups per moles of monosaccharide units of the guar. The molar
substitution
can be determined by the Zeisel-GC method. The molar substitution utilized by
the present
invention is typically in the range of from about 0.001 to about 3.
In one embodiment, the polysaccharide derivative of the invention may further
contain
hydrophobic substituents.
The hydrophobic modification of a polysaccharide derivative of the invention
may be
obtained by the introduction of hydrophobic group.
Typical derivatizing agents bringing a hydrophobic group include 02- 024
linear or branched
alkyl and alkenyl halides, or 06-024 linear or branched alkyl and alkenyl
epoxides and alkyl
and alkenyl glycidyl ethers containing a 04-024 linear or branched hydrocarbon
group.
A hydrophobically modified polysaccharide derivative of the invention may have
hydrophobic
degree of substitution ranging from 1*10-5 to 5*10-1, preferably from 1*10-4
to 1*10-1.
In one embodiment, a hydrophobically modified polysaccharide derivative of the
invention
contains as hydrophobic groups 04-024 alkyl chains. The hydrophobizing agent
is
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preferably a alkyl or alkenyl glycidylether containing a 04-024 linear or
branched
hydrocarbon group.
After the preparation, the polysaccharide derivative of the invention can be
treated with
several known reagents, for example : caustic; acids; biochemical oxidants,
such as
galactose oxidase; chemical oxidants, such as hydrogen peroxide; and enzymatic
reagents;
or by physical methods using high speed agitation machines; thermal methods;
and
combinations of these reagents and methods. Reagents such as sodium
metabisulfite or
inorganic salts of bisulfite may also be optionally included.
The treatments described here above can be also performed on the
polysaccharide
.. derivative of the invention before the derivatization process.
In a preferred embodiment, the polysaccharide derivative is a depolymerized
polysaccharide
derivative, which has been depolymerized by using chemicals, such as hydrogen
peroxide,
or cellulase enzymes.
Methods for the preparation of a polysaccharide derivative of the invention
are disclosed for
instance in U.S. Pat. Nos. 4,663,159; 5,473,059; 5,387,675; 3,472,840;
4,031,307; 4,959,464
and US 2010/0029929, all of which are incorporated herein by reference.
According to the present invention, the polysaccharide derivative is a
cationic polysaccharide
derivative.
According to anyone of the invention embodiments, the polysaccharide
derivative is a
cationic polysaccharide derivative having a cationic degree of substitution
DScat ranging
from about 0.001 to about 3.
According to anyone of the invention embodiments, the cationic polysaccharide
derivative of
the invention may further comprise non ionic substituent groups, for instance
hydroxyalkyl
groups, such as hydroxypropyl groups.
A cationic polysaccharide derivative of the invention may further have a
hydroxyalkyl molar
substitution ranging from 0.001 to 3.
According to anyone of the invention embodiments, the polysaccharide
derivative is a
cationic polysaccharide derivative having a weight average molecular weight
ranging from
about 2,000 to about 3,000,000 g/mol.
The weight average molecular weight of a polysaccharide derivative of the
invention may be
measured for instance by SEC-MALS or by using gel permeation chromatography.
According to one of the invention embodiments, the cationic polysaccharide
derivative of the
invention is a cationic galactomannan derivative, for instance a cationic guar
derivative.
According to one of the invention embodiments, the cationic polysaccharide
derivative of the
.. invention is a cationic galactomannan derivative, for instance a cationic
guar derivative,
having a cationic degree of substitution DScat comprised between about 0.01
and about
0.15, for instance between about 0.05 and about 0.15 and a weight average
molecular
weight comprised between about 10,000 g/mol and about 2,000,000 g/mol, for
instance
between about 200,000 g/mol and about 1,400,000 g/mol.
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According to another one of the invention embodiments, the cationic
polysaccharide
derivative of the invention is a cationic galactomannan derivative, for
instance a cationic guar
derivative, having a cationic degree of substitution DScat comprised between
about 0.25 and
about 0.40, and a weight average molecular weight comprised between about
200,000 g/mol
and about 1,000,000 g/mol, for instance between about 250,000 g/mol and about
850,000 g/mol.
According to another one of the invention embodiments, the cationic
polysaccharide
derivative of the invention is a cationic galactomannan derivative, for
instance a cationic guar
derivative, having a cationic degree of substitution DScat comprised between
about 0.01 and
about 0.15, a hydroxyalkyl molar substitution comprised between about 0.1 and
about 1 and
a weight average molecular weight comprised between about 500,000 g/mol and
about
2,000,000 g/mol.
According to another one of the invention embodiments, the cationic
polysaccharide
derivative of the invention is a cationic galactomannan derivative, for
instance a cationic guar
derivative, having a cationic degree of substitution DScat comprised between
about 0.01 and
about 0.40, a hydroxyalkyl molar substitution comprised between about 0.1 and
about 1 and
a weight average molecular weight comprised between about 2,000 g/mol and
about
90,000 g/mol.
According to another one of the invention embodiments, the cationic
polysaccharide
derivative of the invention is a cationic tamarind gum derivative, for
instance a cationic
tamarind gum derivative having a cationic degree of substitution DScat ranging
from about
0.001 to about 3.
OTHER COMPONENTS
The herbicidal compositions of the present invention optionally may further
comprise at least
one non-auxin herbicide.
The term "non-auxin herbicide" refers to a herbicide having a primary mode of
action other
than as an auxin herbicide. Representative examples of non-auxin herbicides
include acetyl
CoA carboxylase (ACCase) inhibitors, acetolactate synthase (ALS) inhibitors,
acetohydroxy
acid synthase (AHAS) inhibitors, photosystem ll inhibitors, photosystem I
inhibitors,
protoporphyrinogen oxidase (PPO or Protox) inhibitors, carotenoid biosynthesis
inhibitors,
enolpyruvyl shikimate-3-phosphate (EPSP) synthase inhibitor, glutamine
synthetase inhibitor,
dihydropteroate synthetase inhibitor, mitosis inhibitors, and nucleic acid
inhibitors; salts and
esters thereof; racemic mixtures and resolved isomers thereof; and
combinations thereof.
According to anyone of the invention embodiments, the herbicidal compositions
of the
invention further comprise glyphosate or glufosinate, or an agriculturally
acceptable salt
thereof such as, for example, the ammonium, diammonium, dimethylammonium,
monoethanolamine, isopropylamine, and potassium salt thereof.
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According to one of the invention embodiments, the herbicidal compositions of
the present
invention comprise dicamba, or an agriculturally acceptable salt or ester
thereof, and
glyphosate, or an agriculturally acceptable salt thereof.
According to another one of the invention embodiments, the herbicidal
compositions of the
5 present invention comprise 2,4-D, or an agriculturally acceptable salt or
ester thereof, and
glyphosate, or an agriculturally acceptable salt thereof.
The herbicidal compositions of the present invention optionally may further
comprise
conventional additives such as surfactants, drift reduction agents, safeners,
solubility
enhancing agents, thickening agents, flow enhancers, foam-moderating agents,
freeze
10 protectants, UV protectants, preservatives, antimicrobials, and/or other
additives that are
necessary or desirable to improve the performance, crop safety, or handling of
the
composition.
According to anyone of the invention embodiments, the adjuvant and/or
herbicidal
composition of the invention comprises less than about 10 ppm of ammonium
sulfate, or
even no (0 ppm) ammonium sulfate. In this case, buffering and/or water
conditioning may be
provided by alternative additives, such as for instance dipotassium phosphate
or potassium
carbonate.
According to one embodiment, in particular when the polysaccharide derivative
is a tamarind
gum derivative, such as a tamarind seed gum polymer, for instance a
hydroxypropyl
tamarind, the adjuvant and/or herbicidal composition of the invention does not
comprise a
combination of dipotassium phosphate and tri-potassium citrate.
According to another embodiment, in particular when the polysaccharide
derivative is a
tamarind gum derivative, such as a tamarind seed gum polymer, for instance a
hydroxypropyl tamarind, the adjuvant and/or herbicidal composition of the
invention does not
comprise a combination of di-potassium phosphate, potassium nitrate and tri-
potassium
citrate.
HERBICIDAL COMPOSITION EMBODIMENTS AND COMPONENT LOADING
The herbicidal compositions of the invention can be presented in various forms
depending
upon the intended use and handling properties desired.
For example, as detailed in US2014128264, the herbicidal compositions of the
present
invention can be prepared in dry powder form or in liquid form, particularly
aqueous solutions
or dispersions. The term "aqueous" as used in this application, however, is
not intended to
exclude the presence of non-aqueous (i.e., organic) solvents as long as water
is present.
Non-aqueous solutions or dispersions, for instance oil dispersions or
dispersions in organic
solvents are also within the scope of the present invention.
Among the various composition presentations of the invention are the following
:
(a) a ready-to-use herbicidal composition that can be applied to unwanted
plants without the
need for further dilution with a solvent or other preparation;
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(b) a herbicidal composition concentrate that is diluted with a solvent, e.g.
water, and
optionally combined with other herbicide and non-herbicide materials, prior to
application
(including, e.g., dry mixes and premixes);
(c) a herbicidal composition application mixture prepared by diluting a
herbicidal composition
concentrate with a solvent, e.g. water, to form the herbicidal composition
application mixture
which then can be applied to auxin-susceptible plants;
(d) a herbicidal composition application mixture prepared by combining two or
more separate
components with a solvent, e.g. water, (e.g., a tank mix) to form the
herbicidal composition
application mixture which then can be applied to auxin-susceptible plants; and
.. (e) a herbicidal composition application mixture prepared by introducing
separate feed
streams to a spraying or application system so that the feed streams are co-
mixed to form
the herbicidal composition application mixture immediately prior to use.
Suitable amounts, concentrations, and/or mass ratios of the auxin herbicide,
polysaccharide
derivative as defined according to the invention, and optional non-auxin
herbicide will depend
.. to some extent upon whether the composition is a ready-to-use composition,
a concentrate
to be diluted with a solvent, e.g. water, prior to application (e.g., a
"premix"), or a herbicidal
composition prepared by combining two or more herbicide components, a solvent
(e.g. water), and, optionally, other non-herbicide components (e.g., a "tank
mix").
Typical herbicide loading (recited e.g. in U52014128264) are the following.
.. Concentrated herbicidal compositions of the present invention typically
comprise on an acid
equivalent basis (a.e.), for example, from about 120 to about 600 g a.e./L
total herbicide
loading.
Ready-to-use herbicidal compositions and other herbicidal compositions of the
present
invention requiring no further processing prior to application (e.g., diluted
concentrates, tank
mixes, etc.) typically will comprise on an acid equivalent basis (a.e.) from
about 0.1 g a.e./L
to about 50 g a.e./L total herbicide loading.
In herbicidal compositions of the present invention comprising an auxin
herbicide and a non-
auxin herbicide, the weight ratio on an acid equivalent basis of the auxin
herbicide to the
non-auxin herbicide is typically no greater than about 50:1. It may range for
instance from
.. about 25:1 to about 3:1.
As for the polysaccharide derivative loading of the herbicidal composition, it
generally will
depend upon the auxin herbicide loading of the herbicidal composition, the
salt form of the
auxin herbicide, and the properties of any other components of the herbicidal
composition,
and will be an amount sufficient to reduce the volatility of the auxin
herbicide relative to a
reference composition lacking the polysaccharide derivative as defined
according to the
invention, but otherwise having the same composition. For example, the
monoethanolamine
and diethanolamine salts of dicamba are less volatile than the dimethylamine
and
isopropylamine salts of dicamba and the loading required for the less volatile
salts may be
less than the loading required for the more volatile salts. In addition, the
loading of the
polysaccharide derivative as defined according to the invention, can vary with
the specific
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combination of auxin herbicide, optional non-auxin herbicide, and
polysaccharide derivative
as defined according to the invention.
In the herbicidal compositions of the present invention the mass ratio of the
auxin herbicide
to the polysaccharide derivative as defined according to the invention, is
typically no less
than about 3:1 and no greater than about 300:1. Representative mass ratios of
auxin
herbicide acid equivalent (a.e.) to total polysaccharide derivative as defined
according to the
invention, are, for example, from about 3:1 to about 300:1.
In another aspect, the invention provides methods of controlling the growth of
auxin-
susceptible plants, wherein the methods comprise applying to the auxin-
susceptible plants a
herbicidal composition application mixture comprising at least one auxin
herbicide; at least
one cationic polysaccharide derivative; and, optionally, a non-auxin
herbicide; wherein the
application mixture exhibits reduced auxin herbicide volatility relative to an
otherwise
identical application mixture lacking the polysaccharide derivative as defined
according to the
invention
According to anyone of the invention embodiments, the methods of controlling
the growth of
auxin-susceptible plants comprise the steps of: (a) preparing an aqueous
herbicidal
application mixture by diluting with water a herbicidal composition
concentrate of any of the
herbicidal composition concentrates disclosed in this application; and (b)
applying a
herbicidally effective amount of the application mixture to the auxin-
susceptible plants.
In another aspect, the invention provides methods of controlling off-site
movement of an
auxin herbicide, wherein the methods comprise contacting the auxin herbicide
with a
volatility-lowering effective amount of one cationic polysaccharide
derivative, prior to
application of the auxin herbicide.
Another embodiment of the present invention is directed to methods of
counseling an
individual regarding the preparation and/or application of an auxin herbicide
to auxin-
susceptible plants.
Another object of the present invention is to provide an adjuvant which is
useful for reducing
the volatility and off-target movement of any volatile pesticide, such as for
instance trifluralin,
pendimethalin or prosulfocarb.
The addition of a sufficient amount of a polysaccharide derivative as defined
according to the
invention to such volatile pesticides also results in a reduced volatility
upon application
relative to an otherwise identical composition lacking the polysaccharide
derivative as
defined according to the invention.
The invention will now be described in further detail by way of the following
non limiting
examples, wherein the abbreviations have the usual meaning in the art.
EXAMPLES
1/ Preparation of Dicamba salt with/without adjuvants
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Reference solution : "Dicamba DMA 500 g/L a.e. aqueous solution" was prepared
by
dissolving DMA Dicamba (solid form) into deionised water while stirring
(magnetic stirrer) at
room temperature (see Table 1).
.. Solutions with adjuvant: "Dicamba DMA 500 g/L a.e. aqueous solution with
adjuvant" were
prepared as follows : 0.065 g of adjuvant was slowly added in 9.935 g of
reference solution,
so as to obtain a solution containing 0.65 % wt. of adjuvant. This solution
was left under
stirring until adjuvant is fully dissolved at room temperature (see Table 2).
Weight (g)
Dicamba DMA (97%) 62.079
Water 54.413
Table 1 : Preparation of Reference solution "Dicamba DMA 500 g/L a.e. aqueous
solution"
Weight (g)
Dicamba DMA (500 g/L a.e.) 9.935
Adjuvant 0.065
Table 2: Preparation of solution with adjuvant "Dicamba DMA 500 g/L a.e.
aqueous solution
with adjuvant"
2/ Volatility assessment
With a 3 ml plastic pipette, 2 g of aqueous solution ("Dicamba DMA 500 g/L
a.e. aqueous
solution" or "Dicamba DMA 500 g/L a.e. aqueous solution with adjuvant" as
prepared in 1/)
were sampled and deposited as a series of droplets uniformly distributed,
having a diameter
between 2 and 10 mm, onto the aluminum plate (10 cm diameter) of a halogen
moisture
analyzer Mettler Toledo HX 204. An isotherm program was immediately set-up at
75 C
during 5 hours and the solution weight loss % (wt. loss %) was recorded over
this time
period. The volatility extent was assessed by calculating the weight loss %
per hour defined
as the slope of the curve over the time period between 2 and 5 hours. Each
experiment was
repeated a minimum of 3 times and the standard deviation (SD) was calculated.
Efficiency of volatilization decrease has been defined by the following
equation and allows
comparing the ability of the different adjuvants to decrease volatility (see
Table 3)
Slope 2-5h (%/h)
Dicamba DMA SOO g/L aqueous solution ¨S/Ope 2-5h (AM)
,Dicamba DMA SOO g/L aqueous solution with adjuva
Slope 2-5h (A/h)Dicamba DMA 500 g/L aqueous solution
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Volatility
extent
lop
S 2-
SD Efficiency of
e
Formulations volatilization
5h (wt.%
decrease
hour)
per
hour)
Reference solution (Dicamba
DMA 500 g/L a.e. aqueous 0.340 0.021
solution)
Dicamba DMA 500 g/L a.e.
aqueous solution with 0,65% of 0.250 0.020 26.5%
polysaccharide derivative 1 a)
Dicamba DMA 500 g/L a.e.
aqueous solution with 0,65% of 0.260 0.015 23.5%
polysaccharide derivative 2 b
Dicamba DMA 500 g/L a.e.
aqueous solution with 0,65% of 0.260 0.013 23.5%
polysaccharide derivative 3
Dicamba DMA 500 g/L a.e.
aqueous solution with 0,65% of 0.270 0.015 20.6%
polysaccharide derivative 4 d
Dicamba DMA 500 g/L a.e.
aqueous solution with 0,65% of 0.280 0.006 17.7%
polysaccharide derivative 5 e
Comparative solution : Dicamba
DMA 500 g/L a.e. aqueous 0.310 0.015 8.8%
solution with 0,65% of Lupasol P
Table 3 : Comparison of different adjuvants. (SD : Standard Deviation)
(a) Guar Hydroxypropyl trimonium chloride having a molecular weight of about
500,000 g/mol and having a cationic degree of substitution of about 0.3,
available
from Solvay
(b) Hydroxypropyl guar hydroxypropyltrimonium chloride having a molecular
weight of
about 1,200,000 g/mol, a cationic degree of substitution of about 0.1 and a
hydroxyalkyl molar substitution of about 0.5, available from Solvay;
(c) Guar Hydroxypropyl trimonium chloride having a molecular weight of about
1,200,000 and having a cationic degree of substitution of about 0.1, available
from
Solvay
(d) Guar Hydroxypropyl trimonium chloride having a molecular weight of about
500,000 g/mol and having a cationic degree of substitution of about 0.1,
available
from Solvay
(e) Guar Hydroxypropyl trimonium chloride having a molecular weight of about
2,000,000 g/mol and having a cationic degree of substitution of about 0.2,
available from Solvay
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All these results demonstrate that auxin herbicide compositions containing, as
adjuvant, a
polysaccharide derivative of the invention exhibit a lower volatility compared
to a control
composition that does not include such an adjuvant.
These results also demonstrate that auxin herbicide compositions containing,
as adjuvant, a
5 polysaccharide derivative of the invention exhibit a lower volatility
compared to a comparative
composition containing Lupasol P as adjuvant.
Lupasol P is a prior art polyethylenimine supplied by BASF that has already
been described
as adjuvant in auxin herbicide compositions, and is thus considered as a
benchmark.
The experimental results provided herewith illustrate that the polysaccharide
of the invention
10 are thus useful adjuvants to reduce volatility and off site movement of
an auxin herbicide.
II. The relative volatility of DMA salt of dicamba contained in aqueous
formulations was also
measured in bottle experiments (24h, nitrogen flow, room temperature).
1/ Preparation of diluted aqueous formulations of Dicamba salt with/without
adjuvants
Concentrated solution of DMA salt of Dicamba (500 g a.e./L) was prepared by
dissolution of
15 26.522 g of solid DMA Dicamba salt slowly added in 23.471 g of distilled
water under
magnetic stirring. 4.680 g of concentrated solution of DMA salt of Dicamba
were diluted into
95.320 g of distillated water in order to reach 2 %wt. a.e. (i.e. 2.4 %wt. DMA
Dicamba), under
magnetic stirring.
In the cases where adjuvants were added: 0.200 g of adjuvants was slowly added
in 99.8 g
of 2 %wt. a.e. (i.e. 2.4 %wt. DMA Dicamba) solution under magnetic stirring
(600 rpm) and
the resulting solution was left under stirring during few hours (to reach
complete solubilization
of adjuvants).
2/ Volatilization system
2.1 Volatilization chamber (glass bottle)
A 1 liter laboratory bottle (borosilicate glass) equipped with trapping system
was used to
assess volatilization. Dicamba contained in the vapor phase was collected in
water phase
(trapping system) prior to analysis.
Prior to use, 1 liter bottle and tubbing were washed two times using ultra-
pure water/acetone
and dried with pure nitrogen.
The 1 liter bottle included inlet and outlet gas (via the cup). Inlet and
outlet connections were
made using 1/4 inch PTFE tube, 1/4 inch BollaTM fitting and 1/4 inch double
ferrule in PTFE. Inlet
gas was injected at the bottom of the bottle while the outlet gas at the top.
5 g of diluted aqueous formulation of DMA Dicamba (2 %wt. a.e.) were
introduced at the
bottom of the glass bottle using a 3 mL standard disposable plastic transfer
pipette.
Once the experiment started, the bottle remained undisturbed for 24h under
controlled
conditions.
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2.2 Controlled conditions (Flow control)
The gas flow was composed of dry nitrogen. The flow is controlled with a mass
flow
controller at 75 standard liters per hour.
Bottle is left at room temperature (range 19-22 C) during 24h. During this
period, Dicamba
present in the gas phase was captured.
2.3 Capture system
The capture system was composed of one glass flask connected to an 8 ball-
column (glass)
using a dip glass tube. The flask was filled with 30 mL of ultra-pure water
and phosphoric
acid in order to reach pH 1.8. This acidic liquid phase trapped the
volatilized Dicamba thanks
to high surface of exchange between gas and liquid.
3/ Volatility assessment
3.1 Analytical method
The acidic liquid phase (20-30 mL) was recovered and injected to HPLC column
(Zorbax Sb-
Aq (4.6x50 mm, 50 microns)). Pumping was done through a 6 port valve (1-2).
Then, the 6 port valve was turned in 1-6 in order to connect the column to the
diode strip
detector.
The mobile phase gradient consisted of 1.2% of phosphoric acid in water (pH
1.8) and
acetonitrile. The mobile phase started at 85% water ¨ 15% Acetonitrile during
10 minutes,
60% water ¨ 40% Acetonitrile during 14 minutes and 100% water during 15
minutes.
3.2 Results
The results show that the volatility of formulations containing 2 wt% a.e. DMA
Dicamba is of
1.36 0.08 ng/L.
A diminution of volatility of an auxin herbicide of the present invention is
systematically
observed. For example, the result shows that the volatility of the formulation
containing 2
wt% a.e. DMA Dicamba with 0.2% wt. of adjuvant (b) is of 0.05 0.02 ng/L.
"ng/L air" refers to the dicamba concentration in the gas phase.
These results demonstrate that auxin herbicide compositions containing, as
adjuvant, a
polysaccharide derivative of the invention exhibit a lower volatility compared
to a composition
that does not include such an adjuvant.
The experimental results provided herewith illustrate that the polysaccharide
of the invention
are thus useful adjuvants to reduce volatility and off site movement of an
auxin herbicide.
