Fluroxypyr ester herbicidal composition and use thereof

Abstract

Herbicidal composition comprising: a fluroxypyr ester (e.g. fluroxypyr methylheptyl ester); an amide of formula (I); and a lactamide of formula (II), wherein R1 is a C5 to C19 alkyl group, R2 and R3 are independently selected from C1 to C6 alkyl and; each of R4 and R5 is independently selected from a C1 to C6 alkyl group. The lactamide may be N,N-diethyl lactamide and the amide may be a mixture comprising N,N-dimethyl octanamide and N,N-dimethyl capramide. The composition may further comprise auxiliaries (e.g. emulsifiers, adjuvants) and herbicidally active compounds (e.g. clomazone or cyhalofop-butyl). Also claimed are a method of preparing the composition by mixing the three essential components and the use of the amide and lactamides of formulae (I) and (II) to increase the stability of an emulsifiable concentrate comprising fluroxypyr ester. Claimed is a method of controlling plant growth comprising applying to the plants or their locus a composition as defined.

Description

The present invention relates to a fluroxypyr ester herbicidal composition, to a method for preparing the composition and to its use in the control of unwanted plant growth. Agrochemicals such as herbicides, pesticides or microbicides are usually combined with carriers and adjuvants to make a formulated product before being sold to end users, such as farmers. On the one hand, the adjuvants and carriers used to prepare the formulations increase the cost of production and can also have an adverse effect on the environment. On the other hand, these ingredients often make a positive contribution to the effect of the preparation. Organic solvents commonly used in formulated agricultural products, in particular hydrocarbon solvents, are examples of carriers with the above-mentioned characteristics. Due to environmental pressures and policy restrictions, formulators are now seeking to prepare formulated agricultural products that contain little or no petroleum hydrocarbon solvents or chlorinated hydrocarbon solvents, while still achieving the same pesticidal effects. [(4-amino-3,5-dichloro-6-fluoropyridin-2-yl)oxy]acetic acid (fluroxypyr) is a known, highly effective herbicide, as are esters of fluroxypyr. Fluroxypyr methylheptyl ester, commercially sold as a herbicide under the name Starane™ (Dow AgroSciences), is a formulation in the form of an emulsifiable concentrate with a concentration of 200 g acid equivalent / liter of the active ingredient in an aromatic solvent. In view of various economic and environmental factors, there is a need for an alternative high-strength formulation of fluroxypur esters. For example, it is desirable to provide a high-strength formulation to reduce transportation and loading costs, to reduce the amount of packaging materials that must be processed, and to reduce the amount of the solvents released in to the environment. High-strength formulations should be stable and maintain potency during storage and transportation. Moreover, the high-strength formulation should preferably be a uniform and clear liquid. The formulation should be stable, that is maintain the efficacy of the active ingredient over time. In particular, the high-strength formulation should not produce crystals and / or precipitates under low temperature conditions. Crystallized components in the formulation reduce the overall efficacy of the composition and present problems to the end user, for example the blocking of a spray equipment upon dilution with water to a suitable application concentration. The main technical limitation of the known aromatic hydrocarbon-based fluroxypyr ester emulsifiable concentrate formulation is the limited stability thereof, in particular at low temperatures and high concentrations. Although chlorinated solvents or methylpyrrolidone solvents can be used to prepare a relatively high concentration of an emulsifiable concentrate preparation, these solvents have unfavourable environmental effects and are not suitable for exposure to low temperatures. A number of attempts have been made to prepare a low-temperature stable and high-strength fluroxypyr ester emulsifiable concentrate formulation. For example, CN101453892A discloses the use of an N,N dimethyl octanamide / capramide solvent to prepare a high-strength fluroxypyr methylheptyl ester emulsifiable concentrate. The preparation has a good low temperature stability, and does not crystallize at -5°C when stored for 2 to 3 weeks. However, it has been found that when the high-strength fluroxypyr methylheptyl ester emulsifiable concentrate prepared using an N,N dimethyl octanamide / capramide solvent alone is diluted with water to a lower concentration for application and use, crystals of fluroxypyr methylheptyl ester form as a precipitate. These crystals may block the spray equipment, which is particularly problematic for farmers. There is still a need for a more suitable solvent or solvent system for formulating fluroxypyr esters, preferably one able to simultaneously solve the problems of low temperature stability and dilution stability of high-strength fluroxypyr ester formulations. An improved formulation of fluroxypyr esters has now been found. More specifically, there has been found a high-strength fluroxypyr ester formulation, which remains stable under low temperature conditions and at a low pesticide concentration upon dilution with water. It has unexpectedly been found that a stable, high-concentration fluroxypyr ester emulsifiable concentrate (EC) formulation can be prepared using a solvent system comprising an amide of formula (I) and a lactamide of formula (II) as set out below. It has been found that the emulsifiable concentrate (EC) formulation of the present invention exhibits an activity in the control of broad-spectrum broadleaf weeds at least as high as the existing commercial formulations based on petroleum hydrocarbon solvents, while exhibiting a high stability of the active ingredient. In a first aspect, the present invention provides a herbicidal composition, comprising: (1) a fluroxypyr ester; (2) an amide of formula (I): R1 - C(O) - N - R2 I R3 (I) wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group; and (3) a lactamide of formula (II): CH3-CH(OH)-C(O)-N-R4 I (ID R5 wherein each of R4 and R5 is independently selected from a Ci to Ce alkyl group. Generally, the present invention relates to a high-strength herbicidal composition containing a fluroxypyr ester, that is a composition containing the fluroxypyr ester in high concentrations. The herbicidal composition includes a fluroxypyr ester in a sufficient concentration to provide a high-strength preparation, but that does not allow the fluroxypyr ester to crystallize at low temperatures or when diluted with water, for example by dilution for spraying during the end use. The herbicidal composition may contain the fluroxypyr ester, based on a fluroxypyr equivalent, in an amount of from 50 g / L, preferably from 75 g / L, more preferably from 100 g / L, still more preferably from 125 g / L, more preferably still from 150 g / L, especially from 175 g / L, more especially from 200 g / L, still more especially from 225 g / L, more especially still from 250 g / L, in particular from 275 g / L. The herbicidal composition may contain the fluroxypyr ester, based on a fluroxypyr equivalent, in an amount of up to 600 g / L, preferably up to 575 g / L, more preferably up to 550 g / L, still more preferably up to 525 g / L, more preferably still up to 500 g / L, especially up to 475 g / L, more especially up to 450 g / L, still more especially up to 425 g / L, more especially still up to 400 g / L, in particular up to 375 g / L. The composition may comprise the fluroxypyr ester in an amount of from 250 g / L to 400 g / L, based on a fluroxypyr equivalent, preferably from 260 to 375 g / L, especially from about 280 to about 350 g / L of fluroxypyr ester based on a fluroxypyr equivalent. This generally corresponds to about 400 g / L to about 500 g / L of fluroxypyr methylheptyl ester, for example. The composition employs an ester of fluroxypyr. Any suitable ester of fluroxypyr may be used in the composition. Esters of fluroxypyr may be represented by the following general formula (III): in which R6 represents a Ci to Cw alkyl group or a group of general formula R7 - 0 - R8 - in which R7 represents a Ci to C10 alkyl group and R8 represents a Ci to Ce alkyl group. In one preferred embodiment, R6 represents an alkyl group having from 1 to 16 carbon atoms, preferably from 2 to 14 carbon atoms, more preferably from 3 to 12 carbon atoms, more preferably still from 4 to 10 carbon atoms. In another preferred embodiment, R6 represents a group of general formula R7 - 0 - R8 - in which R7 represents an alkyl group having from 1 to 10 carbon atoms, preferably from 1 to 8 carbon atoms, more preferably from 2 to 6 carbon atoms, more preferably still 3 or 4 carbon atoms; and R8 represents an alkyl group having from 1 to 6 carbon atoms, preferably from 1 to 5 carbon atoms, more preferably from 1 to 4 carbon atoms, more preferably still an alkyl group having 1, 2, 3 or 4 carbon atoms. Alkyl groups represented by R6, R7 and R8 may be straight chain or branched. Preferred esters of fluroxypyr are, for example, but not limited to, 2-butoxy-1-methylethyl ester, 2-butoxyethyl ester, butyl ester, 2-methylpropyl ester, 2-ethylhexyl ester, 1-decyl ester, 1 -butoxy-2-propyl ester, methylheptyl ester and 1-butoxy-2-butyl ester. Fluroxypyr methylheptyl ester is a particularly suitable active component for the composition of the present invention. The composition of the present invention comprises an amide of formula (I): R1 - C(O) - N - R2 I (I) R3 wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group. In the amides of general formula (I) R1 represents a Cs to C19 alkyl group. R1 preferably represents an alkyl group having from 6 carbon atoms, more preferably from 7 carbon atoms. R1 preferably represents an alkyl group having up to 18 carbon atoms, more preferably up to 17 carbon atoms, still more preferably up to 16 carbon atoms, more preferably still up to 15 carbon atoms, especially up to 15 carbon atoms, more especially up to 14 carbon atoms. R1 is preferably a Ce to C15 alkyl group, more preferably a C7 to C13 alkyl group, with a C7 to C11 alkyl group being suitable for many embodiments, with nonyl being particularly suitable in many embodiments. R1 may be straight chain or branched. Linear alkyl groups are preferred for R1. In the amides of general formula (I) each of R2 and R3 is independently selected from a Ci to Ce alkyl group. Preferably, each of R2 and R3 is independently selected from a Ci to Cs alkyl group, more preferably from a Ci to C4 alkyl group, still preferably from a Ci to C3 alkyl group, especially from a Ci or C2 alkyl group. Methyl is preferred for R2 and / or R3 in many embodiments. R2 and R3 may be the same or different, preferably the same. Preferably, the amides of formula (I) are those in which R1 is C7 to C13 alkyl, preferably linear, and R2 and R3 are both methyl. More preferably, the amides of formula (I) are those in which R1 is C7-C11 alkyl and R2 and R3 are both methyl. In particular, amides in which R1 is n-nonyl and R2 and R3 are both methyl. The composition may comprise a single amide of the general formula (I). A mixture of two or more of the amides of formula (I) may also be used, for example the mixture of an amide of formula (I) in which R1 is C? to C13 alkyl, preferably linear, and R2 and R3 are both methyl. Many preferred embodiments comprise a mixture of two amides of formula (I). The composition may comprise up to 650 g / L of the amide of formula (I), preferably up to 600 g / L, more preferably up to 550 g / L, especially not more than 500 g / L of the amide of formula (I). The composition may comprise at least 100 g / L of the amide of general formula (I), preferably at least 150 g / L, more preferably at least 200 g / L, especially at least 300 g / L of the amide of formula (I). The composition may comprise from 100 g / L to 650 g / L of the amide of formula (I), preferably from 200 g / L to 600 g / L, more preferably from 300 g / L to 500 g / L of the amide of formula (I). The composition of the present invention further comprises a lactam ide of formula (II): CH3 - CH(OH) - C(O) - N - R4 I (II) R5 wherein each of R4 and R5 is independently selected from a Ci to Ce alkyl group. In the lactamides of general formula (II) each of R4 and R5 is independently selected from a O to Ce alkyl group. Preferably, each of R4 and R5 is independently selected from a Ci to Cs alkyl group, more preferably from a Ci to C4 alkyl group, still preferably from a Ci to C3 alkyl group, especially from a Ci or C2 alkyl group. Methyl is preferred for R4 and / or R5 in many embodiments. R4 and R5 may be the same or different, preferably the same. R4 and R5 may be straight chain alkyl groups or may be branched, for example, isopropyl or tert-butyl. The composition may comprise up to 500 g / L of the lactamide of formula (II), preferably up to 450 g / L, more preferably up to 400 g / L, still more preferably up to 350 g / L, more preferably still up to 300 g / L, especially up to 250 g / L of the lactamide of formula (II). The composition may comprise at least 5 g / L of the lactamide of general formula (II), preferably at least 10 g / L, more preferably at least 15 g / L, especially at least 20 g / L of the lactamide of formula (II). The composition may comprise from 5 g / L to 500 g / L of the lactamide of general formula (II), preferably from 10 g / L to 300 g / L, more preferably from 20 g / L to 250 g / L of the lactamide of formula (II). The composition of the present invention is emulsifiable concentrate, that is forms an emulsion of oil-in-water when mixed and diluted with water, for example, at a weight ratio of 1 part of herbicidal composition to 99 parts of water. The emulsion usually forms spontaneously upon mixing. The resulting emulsion may have an average droplet size of greater than 0.1 urn, preferably greater than 0.5 urn, especially greater than 0.8 urn, and most preferably greater than 1.0 urn. The average droplet size can be determined by a laser diffractometer, for example, Malven Mastersizer 2000. In addition, to the components discussed above, the composition of the present invention may comprise one or more surfactants and / or one or more auxiliary agents commonly used in crop protection products, such as emulsifiers, dispersants, wetting agents, adjuvants, cosolvents, penetrants, protective colloids, adhesives, thickening agents, microbicides, antifreezing agents, antifoaming agents, colorants, and tackifiers. The composition of the present invention may comprise one or more surfactants. The surfactant may be present in any suitable amount. The composition may comprise from 1 to 300 g / L of surfactant, preferably from 5 to 250 g / L, and more preferably from 10 to 200 g / L of the surfactant. Suitable surfactants are surface-active compounds, such as anionic, cationic, nonionic and amphoteric surfactants, block polymers, polyelectrolytes, and mixtures thereof. Such surfactants can be used as emulsifiers, dispersants, cosolvents, wetting agents, penetrants, protective colloids or adjuvants. Examples of suitable surfactants are listed in McCutcheon’s, vol. 1: Emulsifiers &Detergents, McCutcheon’s Directories, Glen Rock, USA, 2008 (International or North American version). Suitable anionic surfactants include alkali metal, alkaline earth metal or ammonium salts of sulfonic acid, sulfuric acid, phosphoric acid, and carboxylic acid, and mixtures thereof. Examples of sulfonates are alkyl aryl sulphonates, diphenyl sulfonates, a-olefin sulfonates, lignin sulfonates, sulfonates of fatty acids and oils, sulfonates of ethoxylated alkylphenols, sulfonates of alkoxylated arylphenols, sulfonates of condensed napthalenes, sulfonates of dodecyl-and tridecylbenzenes, sulfonates of naphthalenes and alkylnaphthalenes, sulfosuccinates or sulphosuccinamates. Examples of sulfates are sulfates of fatty acids and oils, sulfates of ethoxylated alkylphenols, sulfates of alcohols, sulfates of ethoxylated alcohols or sulfates of fatty acid esters. Examples of phosphates are phosphate esters. Examples of carboxylates are alkyl carboxylates and carboxylated alcohol or alkylphenol ethoxylates. Preferred anionic surfactants are sulfates and sulfonates. Suitable nonionic surfactants include alkoxylates, N-substituted fatty acid amides, amine oxides, esters, glycosyl surfactants, polymeric surfactants and mixtures thereof. Examples of alkoxylates are compounds such as alcohols, alkylphenols, amines, amides, arylphenols, fatty acids or fatty acid esters alkoxylated with 1 to 50 equivalents. Ethylene oxide and / or propylene oxide can be used for alkoxylation, preferably ethylene oxide. Examples of N-substituted fatty acid amides are fatty acid glucamides or fatty acid alkanolamides. Examples of esters are fatty acid esters, glycerides or monoglycerides. Examples of glycosyl surfactants are sorbitan, ethoxylated sorbitan, sucrose and glucose esters, or alkyl polyglucosides. Examples of polymeric surfactants are homopolymers or copolymers of vinylpyrrolidone, vinyl alcohol or vinyl acetate. Preferred nonionic surfactants are alkoxylates. Nonionic surfactants such as alkoxylates can also be used as adjuvants. Suitable cationic surfactants include quaternary-type surfactants, such as quaternary ammonium compounds having 1 or 2 hydrophobic groups, or salts of long-chain primary amines. Suitable amphoteric surfactants are alkyl betaines and imidazolines. Suitable block polymers include A-B orA-B-Atype block polymers comprising blocks of polyoxyethylene and polyoxypropylene, or A-B-C type block polymers comprising alkanol, polyoxyethylene and polyoxypropylene. Suitable polyelectrolytes include polyacids or polybases, preferably polyacids. Examples of polybases are polyvinylamines or polyethylene amines. Examples of polyacids are acrylic copolymers or AMPS (2-acrylamido-2-methylpropanesulfonic acid) copolymers. Preferably, the polyelectrolytes are copolymers comprising, in the polymerized form, amides containing at least one monomer selected from N-vinyllactam, N- Ci to Ce alkyl acrylamides and N,N-di Ci to Ce alkyl acrylamides; poly(C2 to Ce alkylene glycol) (meth)acrylate and / or mono Ci to C22 alkyl-terminated poly(C2 to Cg alkylene glycol) (meth)acrylate; Ci to Cs alkyl (meth)acrylate; and (meth)acrylic acid. More preferably, the polyelectrolytes are copolymers comprising, in the polymerized form, amides containing at least one monomer selected from N-vinyllactam; mono Ci to C22 alkyl-terminated poly(C2 to Ce alkylene glycol) (meth)acrylate; Ci to Cs alkyl (meth)acrylate; and (meth)acrylic acid. In another preferred form, the polyelectrolytes are copolymers comprising, in the polymerized form, 25 to 85 % by weight of amides containing at least one monomer selected from N-vinyllactam; 1 to 40 % by weight of mono Ci to C22 alkyl-terminated poly(C2 to Ce alkylene glycol) (meth)acrylate; 5 to 50 % by weight of Ci to Cs alkyl (meth)acrylate; and up to 15 % by weight of (meth)acrylic acid, wherein the sum of the monomers equals 100 %. In another preferred form, the polyelectrolytes are copolymers comprising, in the polymerized form, 30 to 85 % by weight of amides containing at least one monomer selected from N-vinyllactam; 5 to 20 % by weight of mono Ci to C22 alkyl-terminated poly(C2 to Ce alkylene glycol) (meth)acrylate; 8 to 35 % by weight of Ci to Cs alkyl (meth)acrylate; and 0.5 to 10 % by weight of 10 (meth)acrylic acid, wherein the sum of the monomers equals 100 %. In another preferred form, the polyelectrolytes are copolymers comprising, in the polymerized form, at least one ethylenically unsaturated monomer containing a sulfonic acid group, at least one monomer selected from Ci to C4 alkyl (meth)acrylate and at least one monomer selected from Cg to C22 alkyl (meth)acrylate. In another preferred form, the polyelectrolytes are copolymers comprising, in the polymerized form, 5 to 50 % by weight of at least one ethylenically unsaturated monomer containing a sulfonic acid group, 20 to 70 % by weight of at least one monomer selected from Ci to C4 alkyl (meth)acrylate and 5 to 30 % by weight of at least one monomer selected from Cg to C22 alkyl (meth)acrylate, based on the total weight of the monomer. Suitable adjuvants are compounds that have negligible pesticide activity or even have no pesticide activity and improve the biological performance of the pesticide on a target object. Examples are surfactants, mineral oils or vegetable oils and other auxiliary agents. Other examples are listed by Knowles, Adjuvants and additives, Agrow Reports DS256, T&F Informa UK, 2006, Chapter 5. Suitable microbicides include bronopol and isothiazolinone derivatives such as alkylisothiazolinones and benzoisothiazolinones. Suitable antifreezing agents include ethylene glycol, propylene glycol, urea and glycerol. Suitable antifoaming agents include polysiloxanes, long-chain alcohols and fatty acid salts. Suitable colorants (for example red, blue or green) include low water-soluble pigments and water-soluble dyes. Examples are inorganic colorants (such as iron oxide, titanium oxide, and iron hexacyanoferrate) and organic colorants (such as alizarin colorants, azo colorants, and phthalocyanine colorants). In addition to the above-mentioned components, the composition may comprise one or more additional herbicidal compounds that do not have an antagonistic effect on the fluroxypyr ester active substance. Suitable herbicidal compounds include but are not limited to: 2,4-D, 2,4-MCPA, cyhalofop-butyl, ametryn, aminopyralid, asulam, atrazine, butafenacil, carfentrazone-ethyl, chlorflurenol, chlormequat, chlorpropham, chlorsulfuron, chlortoluron, cinosulfuron, clethodim, clopyralid, cyclosulfamuron, pyroxsulam, dicamba, dichlobenil, dichlorprop-P, diclosulam, diflufenican, diflufenzopyr, diuron, glyphosate, hexazinone, imazamox, imazapic, imazapyr, imazaquin, imazethapyr, imazosulfuron, MCPA, metsulfuron-m ethyl, picloram, pyrithiobac-sodium, sethoxydim, sulfometuron, sulfosate, sulfosulfuron, tebuthiuron, terbacil, thiazopyr, thifensulfuron, triasulfuron, tribenuron and triclopyr. In a further aspect, the present invention provides a method for preparing the herbicidal composition hereinbefore described, the method comprising mixing: (1) a fluroxypyr ester; (2) an amide of formula (I): R1 - C(O) - N - R2 I R3 (I) wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group; and (3) a lactamide of formula (II): CH3 - CH(OH) - C(O) - N - R4 I (II) R5 wherein each of R4 and R5 is independently selected from a Ci to Ce alkyl group. The optional components discussed hereinbefore may be included in the mixture, as required. Suitable techniques for combining and mixing the components are known in the art. In a still further aspect, the present invention provides a fluroxypyr ester-containing emulsion comprising a composition as hereinbefore described dispersed in water. The emulsion of this aspect of the invention may be prepared by mixing water with the fluroxypyr ester herbicidal composition of the present invention. Suitable techniques for forming the emulsion are known in the art and are routinely applied, for example by the end users of herbicidal formulations, such as farmers, shortly before applying to the plants and / or locus being treated. The emulsion usually forms spontaneously during mixing of the composition of the present invention with water. In most cases, the emulsion is an oil-in-water emulsion. The ratio of water to fluroxypyr ester herbicidal composition may be any suitable ratio to provide the required application rate of the active components. Generally, water is employed in at least an equal amount by weight, preferably in excess of the amount of the fluroxypyr ester herbicidal composition. For example, the ratio of water to the fluroxypyr ester herbicidal composition may be from 1000 : 1 to 1 :1, preferably from 200 : 1 to 3 : 1. In a further aspect, the present invention provides a method of controlling plant growth at a locus, the method comprising applying to the plants or their locus a composition as hereinbefore described or a fluroxypyr ester-containing emulsion as hereinbefore described. Techniques for applying the formulations to plants and / or their locus are well known and often practised in the art and include, for example, spraying and dipping. In a further aspect, the present invention provides the use of a composition as hereinbefore described or a fluroxypyr ester-containing emulsion as hereinbefore described in the control of plant growth at a locus. In a still further aspect, the present invention provides the use of a mixture comprising: (1) an amide of formula (I): R1 - C(O) - N - R2 (I) R3 wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group; and (2) a lactamide of formula (II): CH3 - CH(OH) - C(O) - N - R4 I (H) R5 wherein each of R4 and R5 is independently selected from a Ci to Ce alkyl group; to increase the stability of an emulsifiable concentrate formulation of a fluroxypyr ester herbicide. The composition of the present invention provides a plurality of advantages. In particular the emulsifiable concentrate fluroxypyr ester herbicidal composition exhibits a high stability, in particular at low temperatures. This manifests in that the fluroxypyr ester in the composition does not precipitate or crystallize at low temperatures, for example at or below -5°C. Further, when the emulsifiable concentrate composition is diluted with water, an emulsion is formed spontaneously. Further, the emulsion is stable for a long time and has little or no tendency to crystallize any of the components. The avoidance of any precipitate or crystal formation significantly reduces or eliminates blockages of spray filters or nozzles. Embodiments of the present invention will now be described, for illustration purpose only, by way of the following working examples. All percentages are weight percent, unless otherwise indicated. In the examples, the following components were used: Active substance: fluroxypyr methylheptyl ester. Amides of formula (1): N,N-dimethyl capramide. Lactamide of formula (II): N,N-dimethyl lactamide. Surfactants: calcium dodecyl benzenesulfonate; castor oil ethoxylate. EXAMPLES Examples 1 to 6 Emulsifiable concentrate (EC) formulations of fluroxypyr methylheptyl ester were prepared from the components listed in Table 1 below. All amounts indicated in Table 1 are in g / L. Table 1 Example No. 1 2 3 4 5 6 Fluroxypyr methylheptyl ester 600 500 480 400 350 300 N,N-dimethyl lactam ide 50 50 100 200 250 20 N,N-dimethyl capramide Make up to 1 L Make up to 1 L Make up to 1 L Make up to 1 L Make up to 1 L Make up to 1 L Calcium dodecyl benzenesulfonate 20 50 30 100 50 10 Castor oil ethoxylate 80 100 60 100 50 10 To form the formulations, the listed components were combined and mixed. 5 The volume in each example was made up to a total volume of 1 L with N, N-dimethyl capramide. Each composition was a clear solution. Each of the formulations of Examples 1 to 6 was subjected to low temperature stability and dilution stability experiments, as follows: io Solubility Experiment 500 ml each of the EC formulations were stored at room temperature. Each formulation was observed after 6 months. The results of the observations are summarised in Table 2 below. Samples 15 that did not show any crystals are indicated as “D”. Samples showing crystal formation are indicated as “ND”. Low Temperature Stability Experiment 500 ml of each of the EC formulations of Examples 1 to 6 were stored at -5°C. Each formulation was observed after 1 month. The results of the observations are summarised in Table 2 below. Samples that did not show any crystals are indicated as “NC”. Samples exhibiting crystal formation are indicated as “C”. Dilution Stability Experiment 10 ml of the EC formulation of each of Examples 1 to 6 were diluted with water by a factor of 200 times by weight. Each diluted sample was then placed in a water bath held at a constant temperature of 25°C. Each diluted sample was observed after 24 hours. The results of the observations are summarised in Table 2 below. Samples that did not show any crystals are indicated as “NC”. Samples exhibiting crystal formation are indicated as “C”. Table 2 Example No. 1 2 3 4 5 6 Solubility D D D D D D Low temperature stability NC NC NC NC NC NC Dilution stability NC NC NC NC NC NC Key: ‘D’ - dissolved; ‘NC’ - not crystallised Example 2 Emulsifiable concentrate (EC) formulations of Fluroxypyr methylheptyl ester were prepared using the components indicated in Table 3 below, for comparison purposes with the formulation of Example 3. 5 Examples Ato E are for comparison purposes and are not embodiments of the present invention. The amounts indicated in Table 3 are in g / L. io Table 3 Example No. 3 A B c D E Fluroxypyr methylheptyl ester 480 480 480 480 480 480 N,N-dimethyl lactam ide 100 - Make up to 1 L - 100 - N,N-dimethyl capram ide Make up to 1 L Make up to 1 L - 100 Calcium dodecyl benzenesulfon ate 30 30 30 30 30 30 Castor oil ethoxylate 60 60 60 60 60 60 Aromatic hydrocarbon solvent - - - Make up to 1 L Make up to 1 L Make up to 1 L The formulations of Example 3 and Comparative Examples Ato E were tested for their solubility, low temperature stability and dilution stability as described in Example 1. The results are set out in Table 4 below. 5 Table 4 Example No. 1 A B C D E Solubility D D D D D D Low temperature stability NC NC C C C NC Dilution stability NC C NC C NC C Key: ‘D’ - dissolved; ‘NC’ - not crystallised; ‘C’ - crystallised io Example 3 Emulsifiable concentrate (EC) formulations of fluroxypyr esters were prepared from the components listed in Table 5 below. All amounts indicated in Table 5 are 15 in g / L. Table 5 Example No. 7 8 9 10 11 12 13 Fluroxypyr butyl ester 300 - 350 - 200 200 Fluroxypyr 2-butoxyethyl ester - 400 - - 400 200 - Fluroxypyr 2-ethylhexyl ester - - 500 - - - 100 Cyhalofop-butyl - - - 150 - - 100 Clomazone - - - 50 - N,N-diethyl lactam ide 10 - 80 100 - - 100 N,N-dipropyl lactam ide - 40 - - 120 150 N,N-dimethyl octanamide Make up to 1 L Make up to 1 L - - Make up to 1 L Make up to 1 L - Mixture of N,N-dimethyl octanamide and capram ide - - Make up to 1 L Make up to 1 L - - Make up to 1 L Alkoxylated fatty alcohol 20 - - 20 15 10 20 Ethoxylated castor oil 70 120 80 60 75 50 40 EO-PO block copolymer - 15 50 - - 30 40 The formulations of Examples 7 to 13 were tested for their solubility, low temperature stability and dilution stability as described in Example 1. The results 5 are set out in Table 6 below. Table 6 Example No. 7 8 9 10 11 12 13 Solubility D D D D D D D Low temperature stability NC NC NC NC NC NC NC Dilution stability NC NC NC NC NC NC NC io Key: ‘D’ - dissolved; ‘NC’ - not crystallised

Claims

1. A herbicidal composition, comprising:(1) a fluroxypyr ester;(2) an amide of formula (I):R1 - C(O) - N - R2I (I)R3wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group; and(3) a lactamide of formula (II):CH3-CH(OH)-C(O)-N-R4I (II)R5wherein each of R4 and R5 is independently selected from a Ci to Cg alkyl group.

2. The herbicidal composition according to claim 1, wherein the composition comprises the fluroxypyr ester in an amount of from 250 g / L to 400 g / L, based on a fluroxypyr equivalent.

3. The herbicidal composition according to either of claims 1 or 2, wherein the fluroxypyr ester has the following general formula (III):in which R6 represents a Ci to Cw alkyl group or a group of general formulaR7 - 0 - R8 -in which R7 represents a Ci to C10 alkyl group and R8 represents a Ci to Ce io alkyl group.

4. The herbicidal composition according to claim 3, wherein the fluroxypyr ester is selected from 2-butoxy-1 -methylethyl ester, 2-butoxyethyl ester, butyl ester, 2-methylpropyl ester, 2-ethylhexyl ester, 1-decyl ester, 1-butoxy-2-propyl ester, 15 methylheptyl ester and 1-butoxy-2-butyl ester.

5. The herbicidal composition according to any preceding claim, wherein R1 is a C? to C13 alkyl group.

6. The herbicidal composition according to any preceding claim, wherein each of R2 and R3 is independently selected from a Ci to C4 alkyl group.

7. The herbicidal composition according to any preceding, wherein the composition comprises from 100 g / L to 650 g / L of the amide of formula (I).

8. The herbicidal composition according to any preceding claim, wherein each of R4 and R5 is independently selected from a Ci to C4 alkyl group.

9. The herbicidal composition according to any preceding claim, wherein the composition comprises from 5 g / L to 500 g / L of the lactam ide of general formula (II).

10. The herbicidal composition according to any preceding claim, further comprising one or more surfactants.

11. The herbicidal composition according to claim 10, wherein the one or more surfactants are present in an amount of from 1 to 300 g / L of surfactant.

12. The herbicidal composition according to any preceding claim, further comprising one or more auxiliaries selected from emulsifiers, dispersants, wetting agents, adjuvants, cosolvents, penetrants, protective colloids, adhesives, thickening agents, microbicides, antifreezing agents, antifoaming agents, colorants, and tackifiers.

13. The herbicidal composition according to any preceding claim, further comprising one or more herbicidally active compounds selected from 2,4-D, 2,4-MCPA, cyhalofop-butyl, ametryn, aminopyralid, asulam, atrazine, butafenacil, carfentrazone-ethyl, chlorflurenol, chlormequat, chlorpropham, chlorsulfuron,chlortoluron, cinosulfuron, clethodim, clopyralid, cyclosulfamuron, pyroxsulam, dicamba, dichlobenil, dichlorprop-P, diclosulam, diflufenican, diflufenzopyr, diuron, glyphosate, hexazinone, imazamox, imazapic, imazapyr, imazaquin, imazethapyr, imazosulfuron, MCPA, metsulfuron-m ethyl, picloram, pyrithiobac-sodium, sethoxydim, sulfometuron, sulfosate, sulfosulfuron, tebuthiuron, terbacil, thiazopyr, thifensulfuron, triasulfuron, tribenuron and triclopyr.

14. A method of preparing a herbicidal composition according to any preceding claim, the method comprising mixing:(1) a fluroxypyr ester;(2) an amide of formula (I):R1 - C(O) - N - R2 IR3(I)wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group; and(3) a lactamide of formula (II):CH3 - CH(OH) - C(O) - N - R4I (II)R5wherein each of R4 and R5 is independently selected from a Ci to Ce alkyl group.

15. A fluroxypyr ester-containing emulsion comprising a composition according to any of claims 1 to 13 or prepared by a method according to claim 14 dispersed in water.

16. The emulsion according to claim 15, wherein the oil droplet size is greater than 0.5 urn.

17. The emulsion according to either of claims 15 or 16, wherein the weight ratio of water to the fluroxypyr ester herbicidal composition is from 200 : 1 to 3 : 1.

18. A method for preparing a fluroxypyr ester-containing emulsion according to any of claims 15 to 17, the method comprising diluting a composition according to any of claims 1 to 13 or a composition produced by a method according to claim 14 with water.

19. A method of controlling plant growth at a locus, the method comprising applying to the plants or their locus a composition according to any of claims 1 to 13 or prepared by a method according to claim 14 or a fluroxypyr ester-containing emulsion according to any of claims 15 to 17.

20. Use of a composition according to any of claims 1 to 13 or prepared by a method according to claim 14 or a fluroxypyr ester-containing emulsion according to any of claims 15 to 17 in controlling plant growth.

21. Use of a mixture comprising:(1) an amide of formula (I):R1 - C(O) - N - R2 IR3(I)wherein R1 is a Cs to C19 alkyl group, and each of R2 and R3 is independently selected from a Ci to Ce alkyl group; and(2) a lactamide of formula (II):CH3-CH(OH)-C(O)-N-R4I (H)R5wherein each of R4 and R5 is independently selected from a Ci to Ce alkyl group;to increase the stability of an emulsifiable concentrate formulation of a fluroxypyr ester herbicide.