WO2013079549A1

WO2013079549A1 - Agrochemical composition

Info

Publication number: WO2013079549A1
Application number: PCT/EP2012/073866
Authority: WO
Inventors: Paul Gioia; Renato MONTEROSSO
Original assignee: Rhodia Operations
Priority date: 2011-12-02
Filing date: 2012-11-28
Publication date: 2013-06-06
Also published as: AU2012261504B2; AU2012261504A1

Abstract

The present invention relates to the use of a synergistic surfactant system in combination with herbicide to improve herbicide bioefficacy. In particular, the present invention relates to an agrochemical composition comprising (i) a herbicide selected from paraquat and/or diquat; and (ii) a surfactant system comprising a synergistic combination of a betaine surfactant; and an additional surfactant comprising an amine or etheramine.

Description

AGROCHEMICAL COMPOSITION

FIELD OF THE INVENTION The present invention relates to an agrochemical composition. In particular, the present invention relates to the use of a synergistic surfactant system in combination with herbicide to improve herbicide bioefficacy, and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

BACKGROUND OF THE INVENTION

The following discussion of the prior art is provided to place the invention in an appropriate technical context and enable the advantages of it to be more fully understood. It should be appreciated, however, that any discussion of the prior art throughout the specification should not be considered as an express or implied admission that such prior art is widely known or forms part of common general knowledge in the field.

Herbicides have a phytotoxic effect on plants, and so they are used in plant production for controlling weeds or totally inhibiting their growth. Herbicides can be non-selective, which means that they destroy all growth, or selective in part or full, whereby they can be used for inhibiting the growth of weeds of only certain crop plants.

The effect of herbicides can be improved by various additives or adjuvants. The most commonly chosen adjuvants are surfactants or surfactant systems. Typically, adjuvants are added to enhance the bioperformance of the herbicide active ingredient, and many such bioperformance enhancing adjuvants are known to those skilled in the art. Without wishing to be bound by theory, it is generally understood that the efficacy of the herbicide is increased by encouraging wetting of the plant by the active ingredient or by encouraging penetration into the plant.

Whilst using surfactant-based adjuvants in combination with herbicidal or agrochemcially-active compounds presents many advantages, certain adjuvants have various drawbacks. For example, International PCT publication number WO 03/063589 describes glyphosate formulations using alkylbetaine surfactants in combination with other surfactants. However, certain alkylbetaine surfactants can either interact with the glyphosate salt thereby increasing the viscosity of the herbicidal formulation, or are generally incompatible with the glyphosate salt solution. Some of these disadvantages were ameliorated in International PCT publication number WO 2005/016002, which teaches the use of glyphosate formulations with certain surfactant-based adjuvants to provide reductions in viscosity.

Other examples comprise PCT publication number WO 01/17358, which describes compositions comprising a high amount glyphosate isopropylamine salt and a surfactant mixture having a surfactant of formula R-CO-NR'-(CR'2)n-COOM. Whilst the surfactant mixture of WO 01/17358 enhances herbicidal effectiveness, the surfactant is expensive and there is a need for other solutions.

There is clearly a need for other surfactants and surfactant systems for use with herbicides, especially to provide compositions that are considered as less ecotoxic, and/or less sensitizing, and/or for compositions that have improved bioefficacy. In particular, there is a constant need for new compositions that preferably provide one or more of the following features:

- low cost, especially low surfactant cost,

- an improved bioefficacy on at least some significant weeds,

- a good compatibility with other herbicides, pesticides, fertilizers, fungicides associated by end-user for example to address some weed resistances,

- a good (low) sensitizing profile,

- a good ecotoxic profile, or an ecotoxic profile considered as good,

- high loads of herbicide that simplify handling and transportation,

- a good stability, typically without crystals formation,

- a compromise of the above.

It is an object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful alternative.

SUMMARY OF THE INVENTION

According to a first aspect the present invention provides an agrochemical composition comprising:

a herbicide selected from paraquat and/or diquat; and

a surfactant system comprising a synergistic combination of: a betaine surfactant; and

an additional surfactant comprising an amine or etheramine. According to a second aspect the present invention provides use of a surfactant system comprising a betaine surfactant and an additional surfactant comprising an amine or etheramine to increase the bio-efficacy of a herbicide comprising paraquat and/or diquat.

According to a third aspect the present invention provides a process for treating vegetation by applying to plants and/or soil a composition according to the first aspect.

According to a fourth aspect the present invention provides a method of killing or inhibiting vegetation or a method of killing plant pests by applying a composition according to the first aspect.

According to a fifth aspect the present invention provides a method of long term weed management comprising the steps of sequentially administering to vegetation a composition according to the first aspect and a glyphosate-containing agrochemical composition.

Preferably the herbicide is selected from paraquat, diquat and mixtures thereof. To the inventor's knowledge, no prior art document discloses the combined use of a betaine surfactant together with an amine/etheramine surfactant in a synergistic combination together with paraquat/diquat to produce an agrochemical composition. Whilst some prior art may utilise a betaine surfactant and/or an amine/etheramine surfactant with glyphosate, no prior art document has taught the composition of the present invention. Further, as the skilled person would understand, the present invention is not an obvious or mere replacement of glyphosate with paraquat/diquat, as the modes of action of these herbicides are very different. To explain, paraquat/diquat, destroys anything that is green and is therefore considered as a fast-acting herbicide, whereas glyphosate has a different mode of action as it kills the whole plant, and is relatively slow-acting, taking weeks to kill vegetation.

To explain further, agronomists have recognised that the continued use of glyphosate requires ever increasing concentrations to kill weeds as repeated treatments tend to build resistance in the plant. Therefore, in order to eradicate the weeds and to prevent super-weeds, the weeds must be treated on a crop rotation basis with a different type of herbicide, for example paraquat/diquat. So for example farmers typically utilise glyphosate continuously until some weed resistance is observed, and then the farmer utilises a paraquat/diquat herbicide. Clearly paraquat/diquat is not a mere substitute for glyphosate.

Further still, farmers cannot simply "tank-mix" paraquat/diquat with glyphosate, because glyphosate takes around 2 weeks to take effect whereas the paraquat/diquat may take 3-4 days. Therefore, by simultaneously treating the plant with both herbicides the glyphosate is prevented from being able to translocate.

It will be appreciated that the terms 'herbicide' and 'agrochemical active ingredient' are used interchangeably herein and include without limitation herbicides, insecticides, fungicides, plant growth regulators and seed treatment agents. It is preferred that the agrochemical compositions of the invention are aqueous compositions and it is especially preferred that the agrochemical active ingredient is a water-soluble agrochemical active. The aqueous agrochemical compositions may generally be applied to the target by spraying and the composition may be a concentrate which is designed to be diluted with water prior to application or may be ready for application. In other words, preferably the composition is a soluble liquid (SL) concentrate.

Specifically, the surfactant system of the present invention may be incorporated into the spray composition prior to application as a "tank mix" or may form a component of an agrochemical concentrate intended for dilution prior to use. It is a particular advantage of the surfactant system of the present invention that the individual surfactants are readily soluble in water and are generally compatible with water-soluble agrochemicals.

Suitable agrochemical active ingredients are known to those skilled in the art and are listed in standard reference books such as the Pesticide Manual. As examples of suitable water-soluble active ingredients there may be mentioned paraquat, diquat, glyphosate, fomesafen, thiamethoxam, mesotrione, trifloxysulfuron or mixtures thereof.

Preferably the agrochemical active ingredient is selected from paraquat and diquat and combinations thereof.

By the term "water-soluble" agrochemical is meant an agrochemical having solubility in water of at least 1 g/1 and preferably at least 4 g/1, for example at least 100 g/1. Of course many agrochemicals have a much higher solubility, for example 300 g/1 or more or up to 500 or 600 g/1 or more. Paraquat and diquat and mixtures thereof are particularly suitable water soluble agrochemical active ingredients. Although the following description will focus on the preferred water soluble agrochemical actives, it is to be understood that other water soluble agrochemical actives may be used in the present invention.

Preferably, aqueous compositions according to the invention contain at least 40 grams per litre of paraquat or diquat or mixtures thereof (individually or in combination referred to herein as bipyridylium salt) expressed as bipyridylium ion. The compositions may contain greater than 50 grams per litre, for example greater than 100 grams per litre of bipyridylium ion.

Compositions containing 200 grams or more per litre may be prepared although a concentration of paraquat in excess of about 250 or 300 g/1 tends to be unstable. In general compositions do not contain greater than 400 grams per litre of bipyridylium ion.

Typically the pH of the paraquat or diquat composition of the invention will be from 3.0 to 7.5 and preferably from 4.0 to 7.0. In other embodiments the pH will be between 4.5 to 6.5, or 5 to 5.5. Other preferred pH ranges will be known to the skilled person. Generally speaking, high pH is to be avoided as this will result in degradation of the paraquat/diquat, and also the betaine could change its charge from a positive to a negative, and could unintendedly and undesirably react with the paraquat/diquat, which is cationic, and therefore counteracts the paraquat/diquat.

Paraquat is the common name of the l,l '-dimethyl-4,4 '-bipyridylium cation. Diquat is the common name of the l,l '-ethylene-2,2'-bipyridylium cation. Salts of paraquat and diquat necessarily contain anions carrying sufficient negative charges to balance the two positive charges on the bipyridylium nucleus.

Since the characteristic herbicidal effect of a bipyridylium quaternary cation is independent of the nature of the associated anion, the choice of the anion is a matter of convenience, depending, for example, on cost. Preferably the anion is one which gives rise to a salt of convenient water solubility. Examples of anions, which may be mono- or polyvalent, include acetate, benzenesulfonate, benzoate, bromide, butyrate, chloride, citrate, fluorosilicate, fumarate, fluoroborate, iodide, lactate, malate, maleate, methylsulphate, nitrate, propionate, phosphate, alicylate, succinate, sulphate, thiocyanate, tartrate, and p-toluenesulfonate. The salt of the herbicidal bipyridylium quaternary cation may be formed from a number of similar anions or mixtures of different ones. For reasons of convenience and economy, paraquat is normally manufactured and sold as paraquat dichloride while diquat is manufactured and sold as diquat dibromide. Since the characteristic herbicidal activity of a salt of a herbicidal bipyridylium quaternary cation resides in the cation only, it is customary to quote concentrations of active ingredient and rates of application in terms of the amount of bipyridylium quaternary cation unless otherwise stated.

Preferably the compositions of the invention are physically stable in the bulk and when diluted with water. Preferably the compositions of the invention do not separate into distinct phases and do not precipitate, either during agitation or when left to stand for long periods.

Preferably the betaine surfactant is selected from selected from alkylbetaines and alkyl(amidoalkyl)betaines. Preferably, the betaine surfactant corresponds to one or more of the following formulae:

(I) R¹R²R²N⁺-CH₂COO-

(II) R¹R³HN⁺-CH₂-CH₂COO-

CH₂CH₂OH

/

(III) Rl-N⁺-CH₂COO-

\

CH₂-COOM

R²

/

(IV) R¹-CON-(CH₂)₃N⁺-CH₂COO-

\

R² in which formulae:

R¹ represents a linear or branched alkyl group containing 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, such as propyl, dodecyl, hexadecyl, tetrahexadecyl, octyl, or mixtures thereof, or an alkamide group, such as dodecanamide;

R , which may or may not be identical, represent an alkyl radical, preferably a methyl radical;

R represents a hydrogen atom or a -CH₂COOM radical or an alkyl radical;

M represents an alkali metal, preferably sodium. These betaine surfactant are commercially available products and are sold by, for example, Rhodia Chimie under the trade names Mirataine® and Wettem® and Geronol®. Advantageously, these commercially available products can be used as they are, without undergoing an initial treatment to reduce the amount of salt, for example (sodium chloride in particular).

In one embodiment the betaine surfactant is non-cyclic.

Preferably the additional surfactant comprises an amine or etheramine comprising at least one hydrocarbon radical containing 2 to 24 carbon atoms. Preferably the additional surfactant is tallow amine ethoxylate (TAE).

In accordance with a first possibility, the additional surfactant is more particularly selected from amines comprising at least one linear or branched, saturated or unsaturated radical containing 2 to 24 carbon atoms, preferably 8 to 18 carbon atoms, optionally comprising 2 to 30 oxyalkylene motifs, preferably oxyethylene, or a mixture of a plurality thereof.

In accordance with a second possibility, the additional surfactant is selected from etheramines comprising at least one linear or branched, saturated or unsaturated radical containing 6 to 24 carbon atoms, preferably 8 to 20 carbon atoms, optionally comprising 2 to 30 oxyalkylene motifs, preferably oxyethylene, or a mixture of a plurality thereof. More particularly, the etheramines correspond to the following formula:

(OA)_x-H

/

(V) R⁵-0-(CH₂)₃-N

\

(OA)_x-H in which formula R⁵ represents a linear or branched, saturated or unsaturated hydrocarbon radical containing 6 to 24 carbon atoms, preferably 8 to 20 carbon atoms; OA, which may or may not be identical from one motif to another and from one branch to another, represent an oxyethylene motif, preferably oxypropylene; and x, x', which may or may not be identical, represent a mean number in the range 1 to 30.

Examples of such amines that can be cited are amines derived from copra and containing 5 oxyethylene (OE) motifs, oleic amines containing 5 OE, amines derived from tallow containing 10 OE, etheramines corresponding to the above formula, in which radical R⁵ is an alkyl radical containing 12 to 15 carbon atoms, the number of OE motifs being in the range 20 to 30.

In accordance with a third possibility, the additional surfactant corresponds to the following formula:

(OA)_x-H

/

(VI) CH₃(CH₂)_Z-N

\

(OA)_x-H wherein z is a number from about 5 to about 23; and x, x' and OA are defined as above.

As discussed above, preferably the amount of the paraquat/diquat in the composition of the invention is in the range 100 to 250 g/1. In one embodiment, the paraquat/diquat is at 200 g/1. Preferably the ratio of betaine:amine/etheramine is between 20:80 to 80:20. Preferred rations are 30:70, 40:60, 50:50, 60:40 and 70:30.

Preferably the total amount of surfactant system is between 10 to 200 g/1. So purely by way of example, a 60:40 ratio of a composition comprising 150 g/1 of surfactant system would comprise 105 g of betaine surfactant and 45 g of amine/ether amine. Other ratios and amounts are possible, as discussed in the above paragraphs.

Further ingredients

The agrochemical composition can comprise further optional ingredients, such as: - surfactants different from the betaine and the amine/etheramine, as part of the surfactant system,

- solvents, preferably water miscible solvent, preferably polar solvents, and/or

- deposition control agents such as anti-rebound or anti-drift agents.

The person skilled in the art understands that these further ingredients that can be used for managing some properties or features of the composition and/or for adding benefits.

The formulations can comprise, for example, organopolysiloxane antifoaming agents. In some cases the composition may create foam, which is generally undesirable when applying the composition to the plant. Therefore, antifoams can also be added to counteract the tendance of the composition to foam. The skilled person will be aware of which kinds of antifoaming materials will be suitable for the present invention. However by way of example only, a suitable antifoam would be a 3 -dimensional siloxane such as Rhodoline DF 5338 AG. A suitable addition rate would be 1.00 g/L, however other addition rates would be well known to the skilled person.

By way of further example, thickening agents can optionally be used such as xanthan gum type polysaccharides, alginates, carboxylated or hydroxylated methylcelluloses, synthetic macromolecules of the polyacrylate, polymaleate, polyvinylpyrrolidone, polyethylene glycol or polyvinyl alcohol type, or of the inorganic type such as bentonites.

Other additives which may be employed are auxiliary additives such as antioxidants, anti-UV agents, colorants, dyes, stenching agents and emetics.

The amount of these additives listed above is normally less than 10% by weight, preferably 1 % by weight or less, advantageously 0.1 % by weight or less compared with the composition weight.

The skilled addressee will understand that the invention comprises the embodiments and features disclosed herein as well as all combinations and/or permeations of the disclosed embodiments and features.

DEFINITIONS

In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the invention pertains.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of ' including, but not limited to ' .

Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term 'about'. The examples are not intended to limit the scope of the invention. In what follows, or where otherwise indicated, '%' will mean 'weight %', 'ratio' will mean 'weight ratio' and 'parts' will mean 'weight parts'.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviations found in their respective testing measurements.

The terms 'predominantly' and 'substantially' as used herein shall mean comprising more than 50% by weight, unless otherwise indicated.

The recitation of a numerical range using endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

The terms 'preferred' and 'preferably' refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

PREFERRED EMBODIMENT OF THE INVENTION

The present invention will now be described with reference to the following examples which should be considered in all respects as illustrative and non-restrictive.

Bipyridylium herbicides, such as Paraquat and Diquat, are non-selective contact herbicides, absorbed by the foliage, with some translocation in the xylem.

Bioefficacy of the formulation is related to the ability to wet and penetrate the waxy leaves of the target weeds/plants, and surfactants find particular utility in lowering the static surface tension (SST) of the herbicide and therefore increase the contact at the surface of the foliage and the ability to penetrate the waxes coating the leaves.

It has been surprisingly discovered that improved bioefficacy of paraquat and/or diquat can be provided by combining alkyl dimethyl betaine (for example Geronol® CF/AS 46-HL) with a Rhodia tallow alkylamine ethoxylate (TAE), such as Fentacare® T15. It was surprisingly found that these two surfactants were compatible in the paraquat soluble liquid formulation; were stable at all storage temperatures; gave a clear solution in soft water (50 ppm hardness) and 1000 ppm hard waters on all application rates, and were free of sedimentation. It is believed that this particular combination of surfactants is a synergistic combination, as discussed further below.

Table 1 : Static surface tension measurements at standard application rates of 1 % w/w solutions by SITA t60 Tensiometer for Paraquat 250 g/L ae SL

NOTE: Gramoxone 250® is a commercially available herbicide product from Syngenta® and includes 250 g/L paraquat present as paraquat dichloride.

SST = static surface tension.

G-H = glass-house.

Geronol® CF/AS 50-HL and CF/AS 46-HL are surfactants from Rhodia® based on alkyl dimethyl betaine 38% and 35% betaine active respectively.

Geronol® MP 900W is based on non-ionic (nonyl phenol ethoxylate) and anionic surfactant blend.

Fentacare® T15 is a tallow alkylamine ethoxylate (15 EO) from Rhodia. Table 1 shows that for a commercially available product (Gramoxone® 250), bio-efficacies of 94% are achievable, and that this product has a SST of 43.5 mN/m. Formulation Composition Bcomprises Geronol® at 150 g/1 with a SST of 36.0 mN/m, (lower to that than Gramoxone® 250), however unexpectedly, its bio-efficacy result were lower to that of the commercially available product (Gramoxone® 250). Surprisingly, in the formulation Composition C, a significantly lower amount of Geronol® was used in synergistic combination with a surprisingly small amount of Fentacare® to provide a high bio-efficacy at a lower SST (39.0 mN/m) of the commercially available product (Gramoxone ®250). Though formulation Composition B, containing Geronol MP900W, having an SST similar to that of Gramoxone ®250 and higher bio-efficacy results, on application the diluted mixture is not stable, resulting with a precipitate forming on standing.

The formulation of the invention possesses several advantages over prior art formulations, such as low viscosity, long term stability, resistance to phase separation, resistance to sedimentation/precipitation, and on dilution the solution remains clear.Without wishing to be bound by theory, it is contemplated that the wetting properties of the alkyl dimethyl betaine are complemented with the penetrating properties of the tallow alkylamine ethoxylate, resulting in a synergistic increase in bio- efficacy in broadleaf weeds, such as wild oats. The two surfactants are compatible in paraquat dichloride soluble liquid concentrate and gave a clear stable solution on dilution, in soft or hard waters. The application of the combined betaine and tallow amine ethoxylate surfactant system enhances the bio-efficacy of bipyridylium herbicide active, thus giving a fast and efficient burn-out time. It is contemplated that these surfactant combinations may also be used for similar formulations of other bipyridylium herbicide actives, e.g. diquat dibromide, or in combinations such as in Spray Seed® from Syngenta® (paraquat/diquat). It is also contemplated that the surface blend of the invention represents a fine balance between wetting of and penetration through the waxy coating of the leaf.

Table 2 below shows that a clear stable solution was provided on dilution in 342 and 1000 ppm hard water. Table 2: Formulation details

NOTE: Application rate was 0.8 g/ 100ml In a second study, a paraquat 250 g/L a.e soluble liquid formulation was developed using Rhodia® surfactants, wherein the formulation was found to be physically and chemically stable after accelerated, medium and long term storage. Product storage stability, which covers accelerated physical and chemical stability of the formulation and active respectively, and long term physical stability of the formulation, are prerequisites to satisfy APVMA Stability-Guidelines for product registration.

Materials and equipment

Paraquat Tech 42 % salt, Lot HUD OK 792 (ex-Eureka)

SUNTEX pH Meter SP-2200

Brookfield Viscometer RVT

100 ml Glass Measuring Cylinder, with stopper

250 ml Glass Measuring Cylinder, with stopper

50 ml density bottle

CIPAC Standard Water D (342 ppm hardness)

Melbourne tap water (30 ppm hardness)

De-ionized water Geronol CF/AS 46 HL, Lot BKH070601

Fentacare T 15, Lot Al 10411420

Rhodoline DF 5338 AG, Lot 11/027 Testing methods

a) Physical Appearance (Visual)

b) Low Temperature Stability: CIPAC MT 39.3

c) Determination of pH Values: CIPAC 75.3

d) Accelerated Storage Test: CIPAC MT 46

e) Persistent Foaming: CIPAC MT 47.2

f) Dilution Stability: CIPAC MT 41

g) Viscosity: Rhodia In-House Test

h) Packaging Stability (Visual in HDPE)

i) Chemical Active Analysis: Performed By Eureka- APS

Formulations

The following formulation was prepared (Table 3) to prepare paraquat 250 g/L a.e SL Table 3: paraquat 250 g/L a.e soluble liquid concentrate formulation

Formulation Composition C

Composition g/L

Paraquat Tech 42% salt 822.30

(equiv. = 347.5 g/L a.e)

Geronol CF/AS 46 HL 105.00

Fentacare T 15 45.00

Rhodoline DF 5338 AG 1.00

Water 135.90

SG 1109.2 Product specifications

Table 4: product specifications for formulation Composition C.

Method of preparation

Sample Composition C was prepared in the following way.

1. Charge vessel with Paraquat Tech.

2. Add Geronol CF/AS 46 HL, stir until homogenous.

3. Add Fentacare T 15, stir until homogenous.

4. Add Rhodoline DF 5338 AG, stir until homogenous.

5. Add Water to Volume

6. Confirm QC Specifications.

Results

Table 5: Physical Stability Results

Formulation Composition C Composition C

Packing Material Glass HDPE

T zero at RT Stable, thin liquid Stable, thin liquid

1 week at 0°C Stable, thin liquid Stable, thin liquid

2 weeks at 54° C Stable, thin liquid Stable, thin liquid 2 weeks at RT Stable, thin liquid Stable, thin liquid

4 weeks at RT Stable, thin liquid Stable, thin liquid

8 weeks at RT Stable, thin liquid Stable, thin liquid

12 weeks at RT Stable, thin liquid Stable, thin liquid

It can be seen from table 5 that the formulation Composition C provides consistent results when contained in either glass or HDPE, and therefore satisfies APVMA Stability-Guidelines for product registration.

Table 6: pH Analysis after accelerated storage

Table 6 shows that the formulation is pH-consistent after accelerated storage. Table 7: Persistent foaming test

NOTE: Formulation Composition C: CIPAC MT 47.2; Rate = 0.8 % v/v; CIPAC

Std D water at ambient temperature (21.8 °C) (342 ppm water hardness)

Table 7 shows that the formulation passes the persistent foaming test. Table 8: Dilution stability

Table 8 shows that the formulation passes the dilution stability test. Table 9: Chemical analysis of active

Table 9 shows that the active content is within accepted 5% tolerance limit.

Discussion

Visual instability is usually manifested by phase separation and discolouration at elevated temperatures. None was observed in this study.

Storage stability trials were carried out in glass and HDPE bottles. Glass bottles were mainly for visual inspection whereas HDPE was used for pH measurements and for chemical stability analysis. Paraquat contained no emetic, odour or dye.

Conclusions

After testing in accordance with standard procedures, the following comments apply: from accelerated stability trials (2 weeks at 54°C), Formulation Composition C containing paraquat at 250 g/L, were found to be physically stable.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. In particular features of any one of the various described examples may be provided in any combination in any of the other described examples.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An agrochemical composition comprising:

a herbicide selected from paraquat and/or diquat; and

a surfactant system comprising a synergistic combination of:

a betaine surfactant; and

an additional surfactant comprising an amine or etheramine.

2. A composition according to claim 1 wherein said paraquat is paraquat dichloride and said diquat is diquat dibromide.

3. A composition according to claim 1 or claim 2 wherein the betaine surfactant is selected from alkylbetaines and alkyl(amidoalkyl)betaines.

4. A composition according to claim 3 wherein the betaine surfactant corresponds to one or more of the following formulae:

(I) R¹R²R²N⁺-CH₂COO-

(II) R¹R³HN⁺-CH₂-CH₂COO-

CH₂CH₂OH

/

(III) R¹-N⁺-CH₂COO-

\

CH₂-COOM

R

(IV) R¹-CON-(CH₂)₃N⁺-CH₂COO-

R . 2 in which formulae:

R¹ represents a linear or branched alkyl group containing 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, such as propyl, dodecyl, hexadecyl, tetrahexadecyl, octyl, or mixtures thereof, or an alkamide group, such as dodecanamide; R , which may or may not be identical, represent an alkyl radical, preferably a methyl radical;

R represents a hydrogen atom or a -CH₂COOM radical or an alkyl radical;

M represents an alkali metal, preferably sodium.

5. A composition according to any one of claims 1 to 4 wherein the amine surfactant comprises at least one linear or branched, saturated or unsaturated radical containing 2 to 24 carbon atoms, optionally comprising 2 to 30 oxyalkylene motifs, or a mixture of a plurality thereof.

6. A composition according to any one of claims 1 to 5 wherein the etheramine surfactant comprises at least one linear or branched, saturated or unsaturated radical containing 6 to 24 carbon atoms, optionally comprising 2 to 30 oxyalkylene motifs, or a mixture of a plurality thereof.

7. A composition according to claim 6 wherein the etheramine surfactant correspond to the following formula:

(OA)_x-H

/

(V) R⁵-0-(CH₂)₃-N

\

(OA)_x-H in which formula R⁵ represents a linear or branched, saturated or unsaturated hydrocarbon radical containing 6 to 24 carbon atoms; OA, which may or may not be identical from one motif to another and from one branch to another, represent an oxyethylene motif; and x, x', which may or may not be identical, represent a mean number in the range 1 to 30.

8. A composition according to claim 7 wherein said amines are derived from copra and contain 5 oxyethylene (OE) motifs, oleic amines containing 5 OE, amines derived from tallow containing 10 OE, etheramines corresponding to the above formula, in which radical R5 is an alkyl radical containing 12 to 15 carbon atoms, the number of OE motifs being in the range 20 to 30.

9. A composition according to any one of claims 1 to 4 wherein the additional surfactant corresponds to the following formula:

(OA)_x-H

/

(VI) CH₃(CH₂)_z-N

\

10. A composition according to any one of claims 1 to 4 wherein the additional surfactant is tallow amine ethoxylate.

11. A composition according to any one of the preceding claims wherein the amount of the paraquat/diquat is between about 100 to 250 g/1.

12. A composition according to any one of the preceding claims wherein the total amount of the surfactant system is between 10 to 200 g/1.

13. A composition according to any one of the preceding claims wherein the ratio of betaine:amine/etheramine is between 20:80 to 80:20.

14. A composition according to any one of the preceding claims wherein the pH of the composition is between 3.0 to 7.5.

15. A composition according to any one of the preceding claims wherein the composition is physically stable in the bulk and when diluted with water.

16. A composition according to any one of the preceding claims wherein the composition does not separate into distinct phases or precipitate upon standing for long periods.

17. Use of a surfactant system comprising a betaine surfactant and an additional surfactant comprising an amine or etheramine to increase the bio-efficacy of a herbicide comprising paraquat and/or diquat.

18. A process for treating vegetation by applying to plants and/or soil a composition according to any one of claims 1 to 16.

19. A method of killing or inhibiting vegetation or a method of killing plant pests by applying a composition according to any one of claims 1 to 16.

20. A method of long term weed management comprising the steps of sequentially administering to vegetation a composition according to any one of claims 1 to 16 and a glyphosate-containing agrochemical composition.