herbicide

Abstract

The present invention relates to a herbicide composition comprising C6-C12 fatty acid, alkyl polyglycoside, C2-C4 polyol, water, fumed silica and a pH sensitive hydrogel forming polymer, wherein the composition has an acidic pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer.

Description

[0001] HERBICIDE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates in general to horticulture, agriculture and the control of undesirable plant growth. In particular, the invention relates to a herbicide composition, a method of preparing the same and the use and application thereof to kill a plant or retard its growth.

[0004] BACKGROUND OF THE INVENTION

[0005] The use of herbicides to control undesirable plant growth is commonplace, both in domestic horticulture and commercial agriculture. Herbicides are also commonly used to control undesirable plant growth around infrastructure such as public amenities, road signs, etc.

[0006] Whilst being beneficial, if not essential, in modern day horti culture / agri culture and infrastructure maintenance, a major drawback of many herbicides currently used is that they are toxic to humans, animals, and the environment in general.

[0007] Herbicides are often categorised into two broad classes, namely systemic herbicides and contact herbicides. Systemic herbicides are absorbed and transported through the plant vascular system thereby killing the entire plant, including the root system. Contact herbicides only adversely affect the part of a plant that has been contacted by the herbicide. While contact herbicides do not generally directly adversely affect the root system of a plant (as they do not typically make contact with the roots), application of such herbicides to the shoot system of the plant and the consequential killing of that shoot system often also causes the root system to die indirectly as the root system can generally not be sustained without an active shoot system.

[0008] Most systemic herbicides are considered highly toxic and there is now a growing movement away from their use toward using contact herbicides.

[0009] For example, glyphosate (N-(phosphonomethyl)glycine) is a non-selective systemic herbicide. Despite being an effective herbicide, extensive use of it has given rise to glyphosate tolerance in the field. Furthermore and more notably, there is ever growing evidence to suggest its use is having a significant deleterious effect on the environment and human health.

[0010] Some contact herbicides are also considered highly toxic and can remain persistent in the environment after use. For example, paraquat (N, N'-dimethyl-4,4'-bipyridinium dichloride) has long been used as an effective contact herbicide. However, its use continues to be banned in many countries due to its persistence in and toxicity to humans, terrestrial and aquatic environments.

[0011] Alternative and more environmentally friendly contact herbicide compositions are known. For example, compositions comprising fatty acids have been shown to exhibit good herbicidal activity. After application, the active fatty acid component in such compositions has been found to quite quickly decompose into relatively non-toxic residues. As an active in herbicidal component, fatty acids show considerable promise.

[0012] However, when used at recommended application rates conventional fatty acid-based herbicide compositions often require a relatively high fatty acid concentration and application rate to promote acceptable herbicidal activity.

[0013] For example, a common application rate of paraquat is typically around 500 L / Ha at a concentration of about 1 L / 100 L, whereas conventional fatty acid herbicides are typically used at application rates of at least 1200 L / Ha and a concentration of about 7.5L / 100 L.

[0014] Despite fatty acid herbicides being environmentally preferred (by being naturally occurring, less toxic and readily biodegradable) compared with other herbicide systems (systemic or contact), their required relatively high concentration and application rate to achieve the desired herbicidal affect presents a potential economic downside.

[0015] Furthermore, conventional concentrate fatty acid herbicide compositions are typically manufactured in the form of a concentrate having no greater than about 50 wt. % of the active fatty acid agent. To provide an effective working herbicide composition, such concentrates typically can only be diluted with water 15 times to provide for about 3.2 wt. % of the active fatty acid agent. In contrast, non-fatty acid based contact herbicides such as paraquat are often sold as a concentrate having about 25 wt. % of paraquat. To provide an effective paraquat working herbicide composition such concentrates can be diluted with water 100 times to provide for a working herbicide having about 0.25 wt. % of the active agent.

[0016] Conventional fatty acid-based herbicide concentrates can therefore be perceived in the marketplace as being inferior as they cannot be diluted to the same extent as other herbicide concentrates and provide for an effective working herbicide composition.

[0017] With contact herbicides such as paraquat being inherently more toxic than fatty acid herbicides, it is at least accepted that fatty acid herbicides are unlikely to match their application efficacy. On the other hand, it is also accepted that the acute toxicity of contact herbicides such as paraquat is resulting in a growing call for them to be banned from use across the world.

[0018] Fatty acid-based herbicide compositions are consequently becoming an increasingly favourable herbicide alternative.

[0019] Accordingly, there remains an opportunity to develop fatty acid-based herbicide compositions with improved economic application and efficacy.

[0020] SUMMARY OF THE INVENTION

[0021] The present invention provides a herbicide composition comprising C6-C12 fatty acid, alkyl polyglycoside, C2-C4 polyol, water, fumed silica and a pH sensitive hydrogel forming polymer, wherein the composition has an acidic pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer.

[0022] It has now been found that a fatty acid herbicide composition can be prepared in the form of a concentrate with a very high fatty acid content (e.g. at least 75 wt. % and up to about 90 wt. %) while remaining as a phase stable composition. Such compositions can advantageously be diluted with water up to at least 50 times and still provide excellent herbicidal efficacy. Surprisingly, compositions in accordance with the present invention demonstrate excellent herbicidal efficacy at fatty acid concentrations below that of conventional fatty acid herbicide compositions. In other words, fatty acid herbicide compositions in accordance with the present invention can surprisingly not only be manufactured as a phase stable concentrate product having a higher fatty acid content than conventional fatty acid herbicide compositions, but they can then be diluted with water to provide for a ready to use product having a fatty acid content (approaching as low as 1.3 wt. %) lower than conventional ready to use fatty acid herbicide compositions (typically higher than 3 wt. %) and still demonstrate excellent herbicidal efficacy.

[0023] While it is known that fatty acids exhibit herbicidal activity, it is also known that simply using the fatty acid alone does not provide adequate herbicidal efficacy. In particular, a composition comprising 100% fatty acid simply does not make for a useful commercial herbicide product.

[0024] After much research, those skilled in the art have developed carrier / delivery systems to use in combination with the fatty acid and provide a useful herbicide product. While the carrier / delivery system in such compositions is essential to realising practical efficacy of the product, those being used in manufacturing conventional fatty acid concentrate herbicide compositions to date do not enable the fatty acid content to exceed about 55 wt. % without composition becoming phase unstable. That fatty acid concentration ceiling is primarily dictated by the problem of producing compositions that have good herbicidal efficacy and remain phase stable (i.e. they do not phase separate into oil and water layers and render the product ineffective). To provide for the typical ready to use herbicide product with a traditional approximate 3.2 wt. % fatty acid, such conventional fatty acid concentrate herbicide compositions can therefore inherently not be diluted any more than about 15-20 times.

[0025] Without wishing to be limited by theory, it is believed the unique carrier / delivery system used in combination with the fatty acid component of the herbicide composition in accordance with the present invention not only allows for the herbicide composition to be produced as a phase stable product at a very high fatty acid content (e.g. at least 75 wt. % and up to about 90 wt. %), but it also synergistically enhances the activity of the fatty acid component to provide for a highly effective herbicide composition demonstrating excellent efficacy at a very low fatty acid content (e.g. approaching only 1.3 wt. % fatty acid). In practical terms, that enables (i) such a concentrate product to be shipped at lower cost (i.e. by having an increased fatty acid content per unit volume), (ii) end-users to not only have the benefit of using an environmentally friendly fatty acid based herbicide, but also one that delivers superior herbicidal efficacy at lower product concentration, and (iii) delivers much lower cost structures compared to conventional fatty acid herbicide compositions.

[0026] In one embodiment, the herbicide composition according to the invention is in the form of a concentrate product comprising the C6-C12 fatty acid in an amount ranging from 75 wt. % to about 90 wt. %, the alkyl polyglycoside in an amount ranging from about 2 wt. % to about 12 wt. %, the C2-C4 polyol in an amount ranging from about 0.5 wt. % to about 5 wt. %, the water in an amount ranging from about 2 wt. % to about 8 wt. %, the fumed silica in an amount ranging from about 0.01 wt. % to about 0.1 wt. % and the pH sensitive hydrogel forming polymer in an amount ranging from about 0.01 wt. % to about 0.1 wt. %.

[0027] In another embodiment, the herbicide composition according to the invention is in the form of a ready to use product comprising the C6-C12 fatty acid in an amount ranging from 1 wt. % to about 5 wt. %, the alkyl polyglycoside in an amount ranging from about 0.05 wt. % to about 0.5 wt. %, the C2-C4 polyol in an amount ranging from about 0.02wt. % to about 0.1 wt. %, the water in an amount ranging from about 95 wt. % to about 99 wt. %, the fumed silica in an amount ranging from about 0.0002 wt. % to about 0.001 wt. % and the pH sensitive hydrogel forming polymer in an amount ranging from about 0.0002 wt. % to about 0.001 wt. %.

[0028] In another embodiment, the herbicide composition according to the invention further comprises a terpene.

[0029] The present invention also provides a method of killing a plant or retarding its growth, and a method or preparing a herbicide composition.

[0030] Further aspects and / or embodiments of the invention are discussed in more detail below.

[0031] DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention provides a herbicide composition. As used herein, the term "herbicide" is intended to take its conventional meaning and define a composition comprising one or more constituent components capable of killing a plant or retarding the plant's growth. Application of the herbicide will generally be employed for killing or retarding the growth of one or more undesirable plant species, for example, one or more weeds. The expressions "herbicidal activity" or "herbicidal efficacy" therefore refers to the potential or realized function of the composition to act as a herbicide and kill a plant or retard a plant's growth.

[0033] Herbicide compositions in accordance with the invention may be classified as a non-selective contact herbicide. In that context, the term "non-selective" refers to the spectrum of plant species against which the herbicide is active, with non-selective herbicides being active against most, if not all, plant species. By being a "contact" herbicide is intended to mean the herbicide only adversely affects the part of a plant that has been contacted by the herbicide. That said, if enough of the contacted plant is adversely affected it may result in a part(s) of the plant not contacted to also become adversely affected, including killing of the entire plant. That being in contrast with a systemic herbicide that is absorbed and transported through the plant vascular system thereby killing the entire plant, including the root system, irrespective of only a part of the plant being contacted by the herbicide.

[0034] Common plant species to which the herbicide compositions according to the invention demonstrate herbicidal activity include, but are not limited to, annual broadleaf weeds (e.g. blackberry nightshade, capeweed, burr medic, milk thistle, spear thistle, wireweed, pigweed, fat hen and shepherd's purse) and annual grasses (e.g. annual ryegrass, crabgrass, crows foot grass and winter grass), perennial broad leaf weeds (e.g. creeping oxalis, flatweed, hair hawkbit, lamb’s tongue, dandelion, evening primrose, bell vine, white clover) and perennial grasses (e.g. couch grass, kikuyu, lovegrass, paspalum, volunteer wheat and perennial ryegrass).

[0035] Herbicide compositions in accordance with the invention are liquid-based and can be conveniently applied to a target plant(s) or locus using conventional liquid-based herbicide application means. Such application means include, but are not limited to, spray, pour or rub applications.

[0036] Herbicide compositions in accordance with the invention will generally be used as a post- emergent (i.e. application directly to a plant shoot(s)) herbicide.

[0037] The herbicide composition according to the invention will typically be applied to make contact with at least some part of the plant structure situated above the ground. For example, the composition may be applied to the plant foliage and / or stem structure.

[0038] The herbicide composition is used in an amount and at a concentration of the constituent components to achieve the desired herbicidal activity. The desired herbicidal activity may be to kill the plant or simply to retard its growth. If required, the desired herbicidal activity may be achieved through multiple applications of the herbicide composition to a plant(s) or locus.

[0039] As those skilled in the art will appreciate, the amount of and concentration of the constituent components in the herbicide composition to be used in a given application will vary depending on a number of factors such as the plant species and the desired herbicidal activity outcome (i.e. to kill the plant or merely retard its growth). Having regard to the teaching herein, those skilled in the art will be able to readily select the amount of and concentration of the constituent components in the herbicide composition to be used in a given application.

[0040] The herbicide composition in accordance with the invention can advantageously be provided in the form of a concentrate product or a so called "ready to use" product. A ready to use product is generally used in the art to describe a product that is derived from a concentrate product by being diluted with water for use in spray applications on, for example, weeds or grasses.

[0041] Having said that, the concentrate product itself can also be used directly on plants typically in specific circumstances such as for hard wood plants like blackberry and lantana by application to an exposed root system and / or application directly to foliage and / or onto a freshly cut stem surface.

[0042] Unless otherwise specified, as used herein the expression “wt. %” is intended to mean the percentage by weight of the specified component relative to the total weight of all components present in the herbicide composition.

[0043] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the C6-C12 fatty acid in an amount of at least 75 wt. %, or at least 80 wt. %, or at least 85 wt. %.

[0044] In another embodiment, the herbicide composition is provided in the form of a concentrate product comprising the C6-C12 fatty acid in an amount ranging from 75 wt. % to about 90 wt. %.

[0045] In one embodiment, the herbicide composition is provided in the form of a ready to use product comprising the C6-C12 fatty acid in an amount of about 1 wt. %, or about 2 wt. %, or about 3 wt. %, or about 4 wt. %, or about 5 wt. %.

[0046] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the C6-C12 fatty acid in an amount ranging about 1 wt. % to about 5 wt. %.

[0047] The herbicide composition in accordance with the invention comprises a C6-C12 fatty acid. Reference to the fatty acid being "C6-C12" is meant that it will contain from 6 to 12 carbon atoms. The fatty acid may be a saturated, unsaturated, straight chain or a branched chain fatty acid.

[0048] In one embodiment, the fatty acid is a straight chain fatty acid.

[0049] In one embodiment the fatty acid is a saturated fatty acid.

[0050] In one embodiment, the C6-C12 fatty acid is selected from caproic acid, enanthic acid, caprylic acid, nonanoic acid (also known as pelargonic acid), capric acid, sebacic acid, udecylic acid and lauric acid.

[0051] In another embodiment, the fatty acid is selected from a Cg-Ciz fatty acid.

[0052] In a further embodiment, the C6-C12 fatty acid comprises nonanoic acid. By being a fatty “acid" it is intended to mean the carbon chain or "fatty" component is covalently attached to a carboxylic acid moiety, where that carboxylic acid is in its protonated form (i.e. not in the form of a salt). In other words, reference to "fatty acid" herein is not intended to be a reference to a fatty acid salt. Compositions in accordance with the invention will generally not comprise a fatty acid salt.

[0053] By the Ce-Cu fatty acid being in its carboxylic acid form, those skilled in the art will appreciate it will have limited if any practical solubility in the water component of the herbicide composition. The water and fatty acid components of the herbicide composition are therefore inherently inclined to present in undesirable oil / water separated phase layers.

[0054] The C6-C12 fatty acid component of the herbicide composition is the main or primary herbicidal active compound in the composition. The herbicide composition in accordance with the invention advantageously does not require the presence of other conventional herbicidal active compounds to attain its efficacy.

[0055] In one embodiment, the herbicide composition in accordance with the invention does not contain a herbicidal active compound at a herbicidal effective concentration other than the C6-C12 fatty acid.

[0056] A herbicidal effective concentration will of course vary depending upon the herbicidal active compound. The herbicidal effective concentration of conventional herbicidal active compounds are well-known to those skilled in the art.

[0057] In one embodiment, the herbicide composition in accordance with the invention does not contain a herbicidal active compound other than the C6-C12 fatty acid.

[0058] In a further embodiment, the herbicide composition in accordance with the invention does not contain one or more one or more herbicidal active compound classes selected from aryloxyphenoxypropionates (fops), cyclohexanediones (dims), phenylpyrazolins, imidazolinones, pyrimidinylthiobenzoic acids, sulfonylaminocarbonyltriazolinones, sulfonylureas, triazolopyrimidines, organophosphorus, arylpicolinates, benzoic acids, phenoxys, semicarbazones, phenylcarbamates, triazines, triazinones, uracils, benzothiadiazoles, nitriles, amides, ureas, isoxazolidinones, isoxazoles, pyrazoles, pyrazolones, triketones, aryl triazinones, diphenylethers, N-phenylphthalimides, pyrimidinediones, bipyridyliums, benzamides, dinitroaniline, thiocarbamates, chloroacetamides, oxyacetamides, pyrazoles, benzofuranes, and arsenical.

[0059] In a further embodiment, the herbicide composition in accordance with the invention does not contain one or more herbicidal active compounds selected from clodinafop, cyhalofop, fenoxaprop, fenoxaprop, quizalofop, clethodim, sethoxydim, pinoxaden, imazamox, imazapic, imazaquin, imazethapyr, bispyribac, pyrithiobac, flucarbazone, propoxy carb azone, thiencarb azone, bensulfuron, chlorimuron, chlorsulfuron, halosulfuron, iodosulfuron, mesosulfuron, metsulfuron, nicosulfuron, orthosulfamuron, primisulfuron, prosulfuron, rimsulfuron, sulfosulfuron, thifensulfuron, triasulfuron, tribenuron, trifloxysulfuron, triflusulfuron, cloransulam, florasulam, florasulam, penoxsulam, penoxsulam, glyphosate, halauxifen, dicamba, aminopyralid, clopyralid, fluroxypyr, triclopyr, quinclorac, 2,4- Dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid, diflufenzopyr, phenmedipham, atrazine, prometryn, simazine, hexazinone, metribuzin, terbacil, bentazon, bromoxynil, propanil, diuron, fluometuron, linuron, glufosinate, fluridone, clomazone, isoxaflutole, pyrasulfotole, topramezone, mesotrione, tembotrione, bicyclopyrone, sulfentrazone, carfentrazone, fluthiacet, acifluorfen, fomesafen, lactofen, flumiclorac, flumioxazin, saflufenacil, diquat, paraquat, pronamide, ethalfluralin, pendimethalin, trifluralin, butylate, cycloate, S-ethyl dipropylthiocarbamate, thiobencarb, triallate, acetochlor, alachlor, s-metolachlor, dimethenamid- P, flufenacet, pyroxasulfone, pyroxasulfone and monosodium methanearsonate.

[0060] The herbicide composition in accordance with the invention further comprises alkyl polyglycoside and C2-C4 polyol. Without wishing to be limited by theory, it is believed the alkyl polyglycoside and C2-C4 polyol play an important role in not only in being able to achieve a phase stable concentrate product, but also in enhancing the manner in which a water diluted ready to use product derived from the concentrate makes the fatty acid component bioavailable on application to a plant. In the form of a water diluted ready to use product, the alkyl polyglycoside and C2-C4 polyol has also been found to facilitate formation of a stable emulsion of the resulting composition.

[0061] It has been found that the use of alkyl polyglycoside and C2-C4 polyol in accordance with the invention is particularly beneficial in maintaining a phase stable composition as the concentration of the C6-C12 fatty acid increases. For example, as the concentration of the C6-C12 fatty acid is increased above at least 70 wt. %, or at least 75 wt. % many conventional stabilizer systems have been found ineffective at maintaining a phase stable product. The use of the alkyl polyglycoside and C2-C4 polyol system surprisingly and advantageously enables the concentration of the C6-C12 fatty acid to be increased above at least 70 wt. %, or at least 75 wt. %, or at least 80 wt. %, or at least 85 wt. % or up to about 90 wt. % without the herbicide composition undergoing undesirable phase separation.

[0062] Reference herein to a "phase stable" product is intended to mean a product that does not phase separate into oil and water layers at ambient temperature and over a time period of at least 1 hour, or at least 2 hours, or at least 3 hours, or at least 4 hours, or at least 5 hours, without stirring or agitation.

[0063] Reference herein to a "stable emulsion" of a water diluted ready to use product is intended to mean the emulsion does not phase separate into oil and water layers at ambient temperature and over a time period of at least 1 hour, or at least 2 hours, or at least 3 hours, or at least 4 hours, or at least 5 hours, without stirring or agitation.

[0064] Alkyl polyglycosides (APG's) are a class of non-ionic surfactants well-known to those skilled in the art.

[0065] APG's are characterised by a saccharide unit and an alkyl chain. Such surfactants can differ in the alkyl chain length, both linear and branched, and in the type of and degree of polymerisation (DP) of the saccharide.

[0066] The saccharide unit of APG's may be a residue of a monosaccharide such as glucose, fructose, lactose, mannose, xylose and the like or a residue or fragment of a polysaccharide or oligosaccharide such as isomaltose, maltose, cellobiose, mellobiose, maltotriose and the like.

[0067] The alkyl chain of APG's will generally comprise 7 about to about 22 carbon atoms.

[0068] The degree of polymerisation of the saccharide unit of APG's will generally range from about >1 to about 20. The degree of polymerisation may be fractional. For example, degree of polymerisation may range from about 1.1 to about 20, or 1.1 to about 10, or about 1.1 to about 3.

[0069] In one embodiment, the alkyl polyglycoside is selected from alkyl polyglucoside. In another embodiment, the alkyl chain of the alkyl polyglycoside comprises about 7 to about 12 carbon atoms.

[0070] In a further embodiment, the alkyl polyglycoside is selected from alkyl polyglucoside in which the alkyl group comprises about 7 to about 12 carbon atoms.

[0071] Examples of APG's suitable for use in accordance with the invention include, but are not limited to, D-Glucopyranose, oligomeric, decyl octyl glycosides (CAS No. 68515-73-1) and D- Glucopyranose, oligomeric, CIO-16 alkyl glycosides (CAS No. 110615-47-9).

[0072] Those skilled in the art will appreciate APG's can be commercially sold as a wt. % solids in water. For avoidance of any doubt, unless otherwise stated, reference herein to a wt. % of an APG is intended to mean the amount of APG per se (not a water composition thereof).

[0073] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the alkyl polyglycoside in an amount ranging from about 2 wt. % to about 12 wt. %, or about 3 wt. % to about 8 wt. %, or about 4 wt. % to about 6 wt. %.

[0074] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the alkyl polyglycoside in an amount ranging from about 0.05 wt. % to about 0.5 wt. %, or about 0.01 wt. % to about 0.5 wt. %.

[0075] Those skilled in the art will be familiar with C2-C4 polyols. Such compounds will comprise at least 2 hydroxy groups and have 2, 3 or 4 carbon atoms. Examples of suitable C2-C4 polyol include ethylene glycol, propylene glycol (all isomers) and butylene glycol (all isomers).

[0076] In one embodiment, the C2-C4 polyol is selected from ethylene glycol, propylene glycol and butylene glycol.

[0077] In a further embodiment, the C2-C4 polyol comprises propylene glycol.

[0078] In another embodiment, the C2-C4 polyol is propylene glycol.

[0079] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the C2-C4 polyol in an amount ranging from about 0.5 wt. % to about 5 wt. %, or about 1 wt. % to about 4 wt. %, or about 1 wt. % to about 3 wt. %.

[0080] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the C2-C4 polyol in an amount ranging from about 0.02 wt. % to about 0.1 wt. %, or about 0.03 wt. % to about 0.09 wt. %.

[0081] The herbicide composition also comprises water.

[0082] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the water in an amount ranging from about 2 wt. % to about 10 wt. %, or about 2 wt. % to about 8 wt. %, or about 2 wt. % to about 6 wt. %.

[0083] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the water in an amount ranging from about 95 wt. % to about 99 wt. %.

[0084] In a further embodiment, the herbicide composition is provided in the form of a ready to use product comprising the water in an amount of about 95 wt. %, or about 96 wt. %., or about 97 wt. %, or about 98 wt. %., or about 99 wt. %.

[0085] The herbicide composition in accordance with the invention also comprises a combination of fumed silica and a pH sensitive hydrogel forming polymer.

[0086] The herbicide composition according to the invention comprises fumed silica and a pH sensitive hydrogel forming polymer, wherein the composition has an acidic pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer.

[0087] Fumed silica is often made from the flame pyrolysis of silicon halide compounds or from quartz sand vaporised at high temperature. The resulting silica particles are very small (generally having a primary particle size ranging from about 5 to 50 nm) and have a high surface area (generally ranging from about 50-600 m2 / g).

[0088] Fumed silica suitable for use in accordance with the invention can be obtained commercially, for example, such as that sold under the name XYSIL®.

[0089] In one embodiment, the fumed silica has a primary particle size of about 5 nm to about 20 nm and a surface area of 100 m2 / g to about 350 m2 / g.

[0090] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the fumed silica in an amount ranging from about 0.01 wt. % to about 0.1 wt. %, or about 0.01 wt. % to about 0.06 wt. %, or about 0.01 wt. % to about 0.04 wt. %, or about 0.01 wt. % to about 0.02 wt. %.

[0091] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the fumed silica in an amount ranging from about 0.0002 wt. % to about 0.001 wt. %, or about 0.0002 wt. % to about 0.0008 wt. %, or about 0.0002 wt. % to about 0.0006 wt. % or about 0.0002 wt. % to about 0.0004 wt. %.

[0092] Those skilled in the art will appreciate fumed silica can be commercially sold as a wt. % solids in water. For avoidance of any doubt, unless otherwise stated, reference herein to a wt. % of fumed silica is intended to mean the amount of fumed silica per se (not a water composition thereof).

[0093] Owing to the small particle size / large surface area of fumed silica, it can be difficult to incorporate into liquid compositions without undesirable agglomeration of the particles. As will be discussed further below, such particle agglomeration during manufacture of the herbicide composition according to the invention can advantageously be minimised or avoided using a pH sensitive hydrogel forming polymer. The herbicide composition in accordance with the invention therefore comprises fumed silica in combination with such a pH sensitive hydrogel forming polymer.

[0094] By a "pH sensitive hydrogel forming polymer" is meant a polymer that forms a hydrogel polymer in response to a change in pH. For example, above a certain pH the polymer presents in the form of a hydrogel and below that pH the polymer will not be in the form of a hydrogel. Such polymers can be tailored to transition into a hydrogel polymer at different pH's. pH sensitive hydrogel forming polymers suitable for use in accordance with the invention will typically contain a plurality of acid functional groups (e.g. carboxylic acid) that at a particular pH present in their acid or protonated form (i.e. in a non-hydrogel form). Upon that pH being increased in the direction of an alkaline pH the acid functional groups of the polymer will ionise and in turn promote formation of the hydrogel polymer.

[0095] In one embodiment, the pH sensitive hydrogel forming polymer is a poly acid polymer. Such pH sensitive hydrogel forming polymers used in accordance with the invention will therefore typically be those that transitions from not being in the form of a hydrogel polymer at an acidic pH into the form of a hydrogel polymer in response to an increase in pH.

[0096] In one embodiment, the pH sensitive hydrogel forming polymer is of a type that transitions from not being in the form of a hydrogel polymer at an acidic pH into the form of a hydrogel polymer in response to an increase in pH.

[0097] The pH sensitive hydrogel forming polymers may, for example, transition into a hydrogel polymer at a pH greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6, or greater than about 6.5, or greater than 7.

[0098] The pH sensitive hydrogel forming polymers may, for example, transition into a hydrogel polymer at a pH in the range of about 4-9, or in the range of about 4-8, or in the range of about 4.5-7, or in the range of about 5-7, or in the range of about 5.5-7.

[0099] By the pH sensitive hydrogel forming polymer transitioning into a hydrogel polymer at a pH in the range of x-y (for example 4-9) is intended to mean that outside that pH range the pH sensitive hydrogel forming polymer is not in the form of a hydrogel and at some point within the specified pH range it will transition into a hydrogel polymer. For example, if the pH range is 4-9, the pH sensitive hydrogel forming polymer may transition into a hydrogel polymer at a pH of about 5, or about 6, or about 7, or about 8. The specified pH range is not intended to mean that the transition into a hydrogel polymer necessarily occurs at outer limits of the range, rather that the transition should occur at a pH somewhere within the range.

[0100] The function of pH sensitive hydrogel forming polymers used in accordance with the invention in preparing the herbicide compositions will be discussed in more detail below.

[0101] The herbicide compositions in accordance with the invention will generally have a pH at which the pH sensitive hydrogel forming polymer presents acid groups that are in their protonated form. In other words, pH sensitive hydrogel forming polymer present in the herbicide composition will generally not be in its hydrogel form.

[0102] The pH sensitive hydrogel forming polymer used in accordance with the invention will therefore be appropriately selected to present in its non-hydrogel polymer form at the pH of the herbicide composition.

[0103] In one embodiment, the herbicide composition has an acidic pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer.

[0104] In one embodiment, the herbicide composition in accordance with the invention has a pH ranging from about 3 to about 5, or about 3 to about 4. pH sensitive hydrogel forming polymers used in accordance with the invention may be a homopolymer or copolymer. pH sensitive hydrogel forming polymers used in accordance with the invention may comprise the polymerised residues of acrylic acid.

[0105] The pH sensitive hydrogel forming polymer may or may not have a degree of crosslinking.

[0106] In one embodiment, the pH sensitive hydrogel forming polymer comprises the polymerised residues of acrylic acid and optionally one or more alkyl acrylates.

[0107] In another embodiment, the pH sensitive hydrogel forming polymer is a polyacrylic acid or an alkyl acrylate crosslinked polymer.

[0108] Suitable pH sensitive hydrogel-forming polymers are readily available commercially. For example, sold by Lubrizol under the name Carbopol®.

[0109] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the pH sensitive hydrogel forming polymer in an amount ranging from about 0.01 wt. % to about 0.1 wt. %, or about 0.01 wt. % to about 0.06 wt. %, or about 0.01 wt. % to about 0.02 wt. %.

[0110] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the pH sensitive hydrogel forming polymer in an amount ranging from about 0.0002 wt. % to about O.OOlwt. %, or about 0.0002 wt. % to about 0.0008 wt. %, or about 0.0002 wt. % to about 0.0006 wt. %, or about 0.0002 wt. % to about 0.0004 wt. %. The herbicide composition in accordance with the invention may further comprise one or more terpenes.

[0111] In one embodiment, the herbicide composition according to the invention comprises one or more terpenes.

[0112] Examples of suitable terpenes that may be used include, but are not limited to, pinene, nerol, citral, menthol, limonene, careen, cineol, camphene, dipentene and terpinolene.

[0113] In one embodiment, the the herbicide composition comprises one or more terpenes selected from pinene, nerol, citral, menthol, limonene, careen, cineol, camphene, dipentene, terpinolene and combinations thereof.

[0114] In another embodiment, the terpene is selected from dipentene, pinene and limonene.

[0115] Those skilled in the art will appreciate terpenes are often derived from extracts of plant oils such as gum turpentine, pine oil, eucalyptus oil, conifer oil, tea tree oil and combinations thereof.

[0116] In one embodiment, the terpene is provided by using one or more of gum turpentine, pine oil, eucalyptus oil, conifer oil, tea tree oil and combinations thereof.

[0117] In one embodiment, the herbicide composition comprises one or more terpenes derived from extracts of one or more of gum turpentine, pine oil, eucalyptus oil, conifer oil, tea tree oil and combinations thereof.

[0118] In one embodiment, the herbicide composition is provided in the form of a concentrate product comprising the one or more terpenes in an amount ranging from about 0.5 wt. % to about 2.5 wt. %, or about 0.75 wt. % to about 2 wt. %, or about 0.75 wt. % to about 1.5 wt. %.

[0119] In another embodiment, the herbicide composition is provided in the form of a ready to use product comprising the one or more terpenes in an amount ranging from about 0.005 wt. % to about 0.1 wt. %, or about 0.007 wt. % to about 0.075 wt. %, or about 0.01 wt. % to about 0.05 wt. Reference herein to an amount (e.g. wt. %) of a component present in the herbicide composition in accordance with the invention may be combined with a referenced amount (e.g. wt. %) of one or more other components present in the herbicide composition to define a particular composition of the herbicide composition.

[0120] For example, in one embodiment, the herbicide composition according to the invention is in the form of a concentrate product comprising the C6-C12 fatty acid in an amount ranging from 75 wt. % to about 90 wt. %, the alkyl polyglycoside in an amount ranging from about 2 wt. % to about 12 wt. %, the C2-C4 polyol in an amount ranging from about 0.5 wt. % to about 5 wt. %, the water in an amount ranging from about 2 wt. % to about 8 wt. %, the fumed silica in an amount ranging from about 0.01 wt. % to about 0.1 wt. %, the pH sensitive hydrogel forming polymer in an amount ranging from about 0.01 wt. % to about 0.1 wt. % and the one or more terpenes in an amount ranging from about 0.5 wt. % to about 2.5 wt. %.

[0121] For example, in another embodiment, the herbicide composition according to the invention is in the form of a ready to use product comprising the C6-C12 fatty acid in an amount ranging from 1 wt. % to about 5 wt. %, the alkyl polyglycoside in an amount ranging from about 0.05 wt. % to about 0.5 wt. %, the C2-C4 polyol in an amount ranging from about 0.02wt. % to about 0.1 wt. %, the water in an amount ranging from about 95 wt. % to about 99 wt. %, the fumed silica in an amount ranging from about 0.0002 wt. % to about 0.001 wt. %, the pH sensitive hydrogel forming polymer in an amount ranging from about 0.0002 wt. % to about 0.001 wt. % and the one or more terpenes in an amount ranging from about 0.005 wt. % to about 0.1 wt. %.

[0122] The herbicide in accordance with the present invention may be prepared by any suitable means. Generally, the herbicide composition prepared in the form of a concentrate product and if desired that concentrate may be suitably diluted with water to provide for a ready to use product.

[0123] A method for preparing the herbicide composition comprises: providing a hydrogel composition, the hydrogel composition comprising fumed silica, C2-C4 polyol and alkyl polyglycoside dispersed throughout a pH sensitive hydrogel forming polymer that is at a pH to present in the form of a hydrogel polymer; and combining the hydrogel composition with C6-C12 fatty acid to provide for the herbicide composition, wherein the so formed herbicide composition has a pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer. In one embodiment, one or more terpenes may be introduced into the hydrogel composition before it is combined with the with C6-C12 fatty acid.

[0124] In another embodiment, one or more terpenes may be introduced into the herbicide composition with or after the C6-C12 fatty acid is combined with the hydrogel composition.

[0125] The hydrogel composition may be prepared by (i) providing an aqueous liquid comprising the fumed silica and combining the aqueous liquid with the pH sensitive hydrogel forming polymer, and (ii) if required adjusting the pH of the hydrogel precursor composition to promote formation of the hydrogel polymer, wherein the C2-C4 polyol and the alkyl polygly coside are combined with the aqueous liquid before or after any pH adjustment occurs.

[0126] In one embodiment, when preparing the herbicide composition according to the invention in the form of a concentrate product, the hydrogel composition may be prepared using about 2 wt. % to about 10 wt. % water, about 0.01 wt. % to about 0.1 wt. % fumed silica, about 0.01 wt. % to about 0.1 wt. % pH sensitive hydrogel forming polymer, about 0.5 wt. % to about 2.5 wt. % C2-C4 polyol and 2 wt. % to about 12 wt. % alkyl polyglycoside.

[0127] In a further embodiment, when preparing the herbicide composition according to the invention in the form of a concentrate product, the so formed hydrogel composition may be combined with about 75 wt. % to about 90 wt. % C6-C12 fatty acid, relative to the total weight of resulting composition.

[0128] In another embodiment, when preparing the herbicide composition according to the invention in the form of a concentrate product, one or more terpenes may be introduced into the hydrogel composition in an amount of about 2 wt. % to about 10 wt. % before it is combined with the Ce- C12 fatty acid, relative to the total weight of resulting hydrogel composition.

[0129] In a further embodiment, when preparing the herbicide composition according to the invention in the form of a concentrate product, one or more terpenes may be introduced into the herbicide composition in an amount of about 0.5 wt. % to about 2.5 wt. % after the C6-C12 fatty acid has been combined with the hydrogel composition, relative to the total weight of resulting composition.

[0130] To prepare a ready to use product from a concentrate product produced in accordance with the invention, the concentrate will generally be diluted with water at least 20 parts, or at least 25 parts, or at least 30 parts, or at parts 35 parts, or at least 40 parts, or at least 45 parts, or at least 50 parts, or at least 60 parts, or at least 70 parts, by volume.

[0131] In one embodiment, a ready to use product is prepared from a concentrate product in accordance with the invention by diluting the concentrate product with water in an amount ranging from about 20 parts to about 70 parts, or about 30 parts to about 70 parts, or about 40 parts to about 70 parts, by volume.

[0132] Where pH adjustment is required during manufacture of the herbicide composition, those skilled in the art will be able to use readily available pH adjusting reagents such as acids or bases.

[0133] For example, increasing the pH may be achieved by using an alkali metal hydroxide such as sodium hydroxide.

[0134] If used, a pH adjusting reagent may be introduced in an amount ranging from about 0.001 wt. % to about 0.05 wt. %, relative to the mass of the composition to which is being introduced.

[0135] Using a pH adjusting reagent during the manufacture of the herbicide composition may be undertaken to increase the pH of a composition to initiate transition of the pH sensitive hydrogel forming polymer into a hydrogel polymer. In other words, the pH adjusting reagent may be used to increase the pH of a composition to a pH that causes the pH sensitive hydrogel forming polymer to form a hydrogel polymer.

[0136] A pH adjusting reagent that causes an increase in pH may be described as an alkaline pH adjusting reagent.

[0137] In one embodiment, an alkaline pH adjusting reagent is used during manufacture of the herbicide composition to cause an increase in pH to greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6, or greater than about 6.5, or greater than 7.

[0138] In another embodiment, an alkaline pH adjusting reagent is used during manufacture of the herbicide composition so as to cause an increase in pH to the range of about 4-8, or in the range of about 4.5-7, or in the range of about 5-7, or in the range of about 5.5-7. In a further embodiment, the hydrogel composition is provided with a pH that promotes hydrogel formation of the pH sensitive hydrogel forming polymer.

[0139] In one embodiment, the hydrogel composition is provided with a pH of greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6, or greater than about 6.5, or greater than 7 to promote hydrogel formation of the pH sensitive hydrogel forming polymer.

[0140] In another embodiment, the hydrogel composition is provided with a pH in the range of about 4- 8, or in the range of about 4.5-7, or in the range of about 5-7, or in the range of about 5.5-7so as to promote hydrogel formation of the pH sensitive hydrogel forming polymer.

[0141] By promoting an increase in the pH of the hydrogel composition such that the pH sensitive hydrogel forming polymer forms a hydrogel, that composition thickens due to the presence of the hydrogel. Increasing the viscosity of the hydrogel composition has been found to facilitate maintaining the fumed silica particles with a substantially uniform distribution throughout the composition. In other words, formation of the hydrogel has been found to assist with minimising or preventing undesirable aggregation of the fumed silica particles within the aqueous based liquid. The resulting hydrogel composition in that thickened state can, if required, then be combined with the other herbicide composition constituent components in a manner that promotes excellent dispersion / distribution of the fumed silica particles within the so formed herbicide composition.

[0142] The so formed hydrogel composition is combined with the C6-C12 fatty acid. Once the Ce-Cu fatty acid is combined with the hydrogel composition the resulting herbicide composition will generally have (due to the acidic character imparted by the fatty acid) a pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer. In the event the presence of the C6-C12 fatty acid does not afford a pH that causes the hydrogel polymer to transition into a non-hydrogel polymer, then the pH of the composition may be adjusted using a pH adjustment agent to cause of the aforementioned transition. Suitable pH adjustment agents to cause a reduction in pH are well known by those skilled in the art and can be readily used. For example, if required the pH may be reduced using hydrochloric acid or acetic acid.

[0143] Generally, combining the hydrogel composition with the C6-C12 fatty acid will promote a sufficient reduction in the pH of the resulting composition that causes the hydrogel polymer to transition into a non-hydrogel polymer.

[0144] The herbicide composition in accordance with the invention will generally have a pH ranging from about 3-6, or from about 3-5, or from about 4-5.

[0145] As alluded to, the pH sensitive hydrogel forming polymer used in accordance with the invention will be of a type that does not present as a hydrogel polymer at the pH of the resulting herbicide composition.

[0146] The present invention further provides a herbicide composition produced according to the method described herein.

[0147] The present invention also provides a method of killing a plant or retarding its growth, the method comprising contacting the plant with a herbicide composition according to the present invention.

[0148] The present invention further provides controlling plant growth at a locus, the method comprising applying to the locus a herbicide composition according to the present invention.

[0149] As used herein, the expression “controlling plant growth at a locus” is intended to mean that plant growth is retarded, inhibited or prevented at the locus. The term “locus” is intended to mean any location where plant growth may occur. For example, the locus may be a region of soil in which a plant may grow or a surface upon which a plant may grow.

[0150] Contacting the plant with or applying to the locus a herbicide composition according to the invention may be achieved by conventional means in the application of herbicide compositions. For example, the herbicide composition may be rubbed or poured directly on to the plant or the locus. Alternatively, the herbicide composition may be sprayed onto the plant or the locus.

[0151] The present invention also provides for use of a herbicide composition according to the invention to kill a plant or retard its growth. The present invention further provides for use of a herbicide composition according to the invention to control growth of a plant at a locus.

[0152] Use of a herbicide composition according to the invention may be performed as herein described and as is well known to those skilled in the art. Unless indicated otherwise, the term "alkyl", used either alone or in compound words, is intended to denote straight chain, branched or cyclic alkyl, preferably C1.20 alkyl, e.g. Ci-io or Ci-6. Examples of straight chain and branched alkyl include methyl, ethyl, / / -propyl, isopropyl, / / -butyl, ec-butyl, / -butyl, / / -pentyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl, 4-m ethylpentyl, 1- m ethylpentyl, 2-m ethylpentyl, 3 -methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3- dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,2,2-trimethylpropyl, 1,1,2- trimethylpropyl, heptyl, 5-methylhexyl, 1 -methylhexyl, 2,2-dimethylpentyl, 3, 3 -dimethylpentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3 -dimethylpentyl, 1,4-dimethyl-pentyl, 1,2,3- trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, octyl, 6-methylheptyl, 1 -methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-m ethyl octyl, 1-, 2-, 3-, 4- or 5- ethylheptyl, 1-, 2- or 3 -propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-, 3- or 4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9- methyldecyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-ethylnonyl, 1-, 2-, 3-, 4- or 5 -propyl octyl, 1-, 2- or 3- butylheptyl, 1 -pentylhexyl, dodecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3- , 4-, 5-, 6-, 7- or 8-ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl, 1-2- pentylheptyl and the like. Examples of cyclic alkyl include mono- or polycyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and the like. Where an alkyl group is referred to generally as "propyl", butyl" etc., it will be understood that this can refer to any of straight, branched and cyclic isomers where appropriate.

[0153] The present invention will hereinafter be described with reference to non-limiting examples.

[0154] EXAMPLES

[0155] Comparative example 1: Composition 1

[0156] Based on the formulation shown in Table 1, a mixture of water, fumed silica, pH sensitive hydrogel forming polymer, alkaline pH adjusting reagent, ethoxylated C9-11 alcohols and polyoxyethylene stearyl cetyl ether was prepared. Nonanoic acid and dipentene was added. The solution was stirred for 15 minutes and filtered through a nylon filter. The resulting solution was sealed and stored in an airtight container.

[0157] Table 1 : Composition 1

[0158] *Nonanoic Acid content: 444.1g / L

[0159] Comparative example 2: Composition 2

[0160] Based on the formulation shown in Table 2, a mixture of water, fumed silica, pH sensitive hydrogel forming polymer, alkaline pH adjusting reagent, ethoxylated C9-11 alcohols and polyoxyethylene stearyl cetyl ether was prepared. Nonanoic acid and dipentene was added. The solution was stirred for 15 minutes and filtered through a nylon filter. The resulting solution was sealed and stored in an airtight container. Table 2: Composition 2

[0161] *Nonanoic Acid content: 664.8g / L

[0162] Example 3: Composition 3

[0163] Based on the formulation shown in Table 3, a mixture of water, fumed silica, pH sensitive hydrogel forming polymer, alkaline pH adjusting reagent, alkyl polyglycoside and polyol was prepared. Nonanoic acid and d-Limonene was added. The solution was stirred for 15 minutes and filtered through a nylon filter. The resulting solution was sealed and stored in an airtight container. Table 3: Composition 3

[0164] *Nonanoic Acid content: 774.3g / L

[0165] Example 4: Composition 4

[0166] Based on the formulation shown in Table 4, a mixture of water, fumed silica, pH sensitive hydrogel forming polymer, alkaline pH adjusting reagent, alkyl polyglycoside and polyol was prepared. Nonanoic acid and d-Limonene was added. The solution was stirred for 15 minutes and filtered through a nylon filter. The resulting solution was sealed and stored in an airtight container.

[0167] Table 4: Composition 4 *Nonanoic Acid content: 747.0g / L Comparative example 5: Composition 5

[0168] Based on the formulation shown in Table 5, a mixture of water, alkyl polyglycoside and polyol was prepared. Nonanoic acid and d-Limonene was added. The solution was stirred for 15 minutes and filtered through a nylon filter. The resulting solution was sealed and stored in an airtight container.

[0169] Table 5: Composition 5

[0170] *Nonanoic Acid content: 792.6g / L Example 6: Composition 6

[0171] Based on the formulation shown in Table 6, a mixture of water, fumed silica, pH sensitive hydrogel forming polymer, alkaline pH adjusting reagent, alkyl polyglycoside and polyol was prepared. Nonanoic acid and d-Limonene was added. The solution was stirred for 15 minutes and filtered through a nylon filter. The resulting solution was sealed and stored in an airtight container.

[0172] Table 6: Composition 6

[0173] *Nonanoic Acid content: 792.6g / L

[0174] Example 7a: Composition 7a A working spray mixture (Composition 7a) was prepared by adding 2% by weight of Composition 6 to 98% by weight of water as set out in Table 7.

[0175] Table 7: Composition 7a.

[0176] *Nonanoic Acid content: 15.5g / L

[0177] Example 7b: Composition 7b

[0178] A working spray mixture (Composition 7b) was prepared by adding 3.6% by weight of Composition 6 to 96.4% by weight of water as set out in Table 8.

[0179] Table 8: Composition 7b.

[0180] *Nonanoic Acid content: 27.6g / L

[0181] Example 8: Field trial applications

[0182] Example 8a: Field trial to evaluate efficacy of Composition 1 and Composition 6 (at different dilutions) for the control of weeds in fallow

[0183] A field trial was conducted in Queensland to evaluate and compare Composition 1 (Nonanoic Acid content: 444.1g / L) at a dilution rate of 50ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 21.1kg / ha), Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 15ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 11.7kg / ha) and Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) for the control of Crowsfoot grass (Eleusine indica), Bittercress (Cardamine hirsuta) and Amaranth (Amaranthus sp.) in fallow. Application treatments were compared with Slasher Weed Killer (525g / L nonanoic acid) at 70ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 34.3kg / ha), Basta 200 SL (200g / L glufosinate) applied at 6.7ml / L of water and a spray volume of 750L / ha and Glyphosate 360SL (360g / L glyphosate) at 8 mL / L of water and a spray volume of 750L / ha and an untreated control (UTC).

[0184] Treatments were applied as a foliar spray to actively growing broadleaf weeds and grasses at the BBCH 12-18 growth stage using air injected flat fan nozzles with a spray volume of l,000L / ha for the nonanoic acid contact herbicides and 750L / ha for the glufosinate and glyphosate systemic herbicide.

[0185] Weed brownout (visual % compared to untreated control) was assessed at 7DAA, 14DAA and 21DAA (days after application) and weed density (plants / m2) was assessed at 0 and 21DAA.

[0186] Composition 1 (Nonanoic Acid content: 444.1g / L) at a dilution rate of 50ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 21.1kg / ha) provided significant control of all weeds compared to the UTC at all assessment timings. Crowsfoot grass, Bittercress and Amaranth brownout (% leaf area) was 95-100% after 7DAA and 100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0.5 versus 2.3 for UTC (Crowsfoot grass).

[0187] Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 15ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 11.7kg / ha) provided significant control of all weeds compared to the UTC at all assessment timings. Crowsfoot grass, Bittercress and Amaranth brownout (% leaf area) was 95-100% after 7DAA and 95-100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0.3 versus 2.3 for UTC (Crowsfoot grass).

[0188] Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) provided significant control of all weeds compared to the UTC at all assessment timings. Crowsfoot grass, Bittercress and Amaranth brownout (% leaf area) was 97-100% after 7DAA and 100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0 versus 2.3 for UTC (Crowsfoot grass).

[0189] Comparing the three spray mixtures containing nonanoic acid: Composition 1 (Nonanoic Acid content: 444.1g / L) at a dilution rate of 50ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 21.1kg / ha), Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 15ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 11.7kg / ha) and Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha). The three spray mixtures delivered high performance of weed control.

[0190] Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 15ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 11 ,7kg / ha) delivered very similar performance compared to Composition 1 (Nonanoic Acid usage: 21.1kg / ha) while reducing nonanoic acid usage by 45%. Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) delivered numerically even better results than Composition 1 (Nonanoic Acid usage: 21.1kg / ha) while reducing nonanoic acid usage by 27%.

[0191] Slasher Weed Killer (525g / L nonanoic acid) at 70ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 34.3kg / ha) provided medium control of all weeds compared to the UTC at all assessment timings. Crowsfoot grass, Bittercress and Amaranth brownout (% leaf area) was 97-100% after 7DAA and 97-100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 1 versus 2.3 for UTC.

[0192] Comparing Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 15ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 11.7kg / ha) and at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) with Slasher Weed Killer spray mixtures containing nonanoic acid, Composition 6 delivered superior weed control performance at significantly reduced nonanoic acid content.

[0193] Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 15ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 11.7kg / ha) delivered superior performance compared to Slasher Weed Killer (525g / L nonanoic acid) at 70ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 34.3kg / ha) while reducing nonanoic acid usage by 66%.

[0194] Comparing Composition 6 (Nonanoic Acid content: 792.6g / L) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) with Basta 200 SL (200g / L glufosinate) applied at 6.7ml / L of water and a spray volume of 750L / ha and Glyphosate 360SL (360g / L glyphosate) at 8 mL / L of water and a spray volume of 750L / ha spray mixtures, Composition 6 delivers comparable weed control for Crowsfoot grass compared to both Basta 200 SL (200g / L glufosinate) and Glyphosate 360SL (360g / L glyphosate), superior weed control for Bittercress compared to Basta, and superior weed control for Amaranth compared to Glyphosate. Example 8b: Field trial to evaluate efficacy of Composition 5 (comparative) and Composition 6 for the control of weeds in fallow

[0195] A field trial was conducted in Victoria to evaluate and compare Composition 5 (Nonanoic Acid content: 792.6g / L, no silica colloid, additional 1.65% by weight Alkyl polyglycoside) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) and Composition 6 (Nonanoic Acid content: 792.6g / L, with silica colloid) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) for the control of Annual ryegrass (Lolium rigidum), Amaranth (Amaranthus blitum) and Fat hen (Chenopodium album) in fallow and an untreated control (UTC).

[0196] Treatments were applied as a foliar spray to actively growing broadleaf weeds and grasses at the BBCH 12-18 growth stage using full cone nozzles with a spray volume of l,000L / ha.

[0197] Weed brownout (visual % compared to untreated control) was assessed at 7DAA, 14DAA and 21DAA (days after application) and weed density (plants / m2) was assessed at 0 and 21DAA.

[0198] Composition 5 (Nonanoic Acid content: 792.6g / L, no silica colloid, additional 1.65% by weight Alkyl polyglycoside) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) provided good control of all weeds compared to the UTC at all assessment timings. Annual ryegrass, Amaranth and Fat hen brownout (% leaf area) was 90- 100% after 7DAA and 85-100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 1 versus 2.3 for UTC (Couch Grass).

[0199] Composition 6 (Nonanoic Acid content: 792.6g / L, with silica colloid) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) provided significant control of all weeds compared to the UTC at all assessment timings. Annual ryegrass, Amaranth and Fat hen brownout (% leaf area) was 97-100% after 7DAA and 100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0.5 versus 2.3 for UTC (Couch Grass).

[0200] Comparing Composition 5 (comparative) (Nonanoic Acid content: 792.6g / L, no silica colloid, additional 1.65% by weight Alkyl polyglycoside) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) with Composition 6 (Nonanoic Acid content: 792.6g / L, with silica colloid) at a dilution rate of 20ml / L of water and a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) spray mixtures containing nonanoic acid, confirms Composition 6 demonstrated enhanced weed control performance at the same nonanoic acid content.

[0201] Example 8c: Field trial to evaluate efficacy of Ready to Use Spray Mixtures Composition 7A and Composition 7B for the control of weeds in fallow

[0202] A field trial was conducted in Victoria to evaluate and compare Composition 7A (Nonanoic Acid content: 15.5g / L) at a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) and Composition 7B (Nonanoic Acid content: 27.6g / L) at a spray volume of l,000L / ha (Nonanoic Acid usage: 27.6kg / ha) for the control of Cat's Ear (Hypochaeris radicata), Ragwort (Senecio jacobaea) amd Paspalum (Paspalum dilatatum) in fallow and an untreated control (UTC).

[0203] Treatments were applied as a foliar spray to actively growing broadleaf weeds and grasses at the BBCH 12-18 growth stage using full cone nozzles with a spray volume of l,000L / ha.

[0204] Weed brownout (visual % compared to untreated control) was assessed at 7DAA, 14DAA and 21DAA (days after application) and weed density (plants / m2) was assessed at 0 and 21DAA.

[0205] Composition 7 A (Nonanoic Acid content: 15.5g / L) at a spray volume of l,000L / ha (Nonanoic Acid usage: 15.5kg / ha) provided significant control of Cat's Ear and Ragwort weeds, and limited control of Paspalum grasses compared to the UTC at all assessment timings. Cat's Ear and Ragwort brownout (% leaf area) was 97-100% after 7DAA and 97-100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0.3 versus 4.1 for UTC (Ragwort). Paspalum brownout (% leaf area) was 80% after 7DAA and 85% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 2.5 versus 5.1 for UTC (Paspalum).

[0206] Composition 7B (Nonanoic Acid content: 27.6 g / L) at a spray volume of l,000L / ha (Nonanoic Acid usage: 27.6kg / ha) provided significant control of Cat's Ear and Ragwort weeds, and Paspalum grasses compared to the UTC at all assessment timings. Cat's Ear and Ragwort brownout (% leaf area) was 100% after 7DAA and 100% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0.1 versus 4.1 for UTC (Ragwort). Paspalum brownout (% leaf area) was 95% after 7DAA and 95% after 21DAA. Weed and grass count (no. / m2) after 21DAA was 0.5 versus 5.1 for UTC (Paspalum). The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0207] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS1. A herbicide composition comprising C6-C12 fatty acid, alkyl polyglycoside, C2-C4 polyol, water, fumed silica and a pH sensitive hydrogel forming polymer, wherein the composition has an acidic pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer.

2. The herbicide composition according to claim 1, wherein the C6-C12 fatty acid is present in an amount ranging from 75 wt. % to about 90 wt. %.

3. The herbicide composition according to claim 1 or 2, wherein the alkyl polyglycoside is present in an amount ranging from about 2 wt. % to about 12 wt. %.

4. The herbicide composition according to any one of claims 1 to 3, wherein the C2-C4 polyol is present in an amount ranging from about 0.5 wt. % to about 5 wt. %.

5. The herbicide composition according to any one of claims 1 to 4, wherein the water is present in an amount ranging from about 2 wt. % to about 8 wt. %.

6. The herbicide composition according to any one of claims 1 to 5, wherein the fumed silica is present in an amount ranging from about 0.01 wt. % to about 0.1 wt. % and the pH sensitive hydrogel forming polymer is present in an amount ranging from about 0.01 wt. % to about 0.1 wt. %.

7. The herbicide composition according to claim 1 in the form of a concentrate product comprising the C6-C12 fatty acid in an amount ranging from 75 wt. % to about 90 wt. %, the alkyl polyglycoside in an amount ranging from about 2 wt. % to about 12 wt. %, the C2-C4 polyol in an amount ranging from about 0.5 wt. % to about 5 wt. %, the water in an amount ranging from about 2 wt. % to about 8 wt. %, the fumed silica is present in an amount ranging from about 0.01 wt. % to about 0.1 wt. % and the pH sensitive hydrogel forming polymer is present in an amount ranging from about 0.01 wt. % to about 0.1 wt. %.

8. The herbicide composition according to claim 1 in the form of a ready to use product comprising the C6-C12 fatty acid in an amount ranging from 1 wt. % to about 5 wt. %, the alkyl polyglycoside in an amount ranging from about 0.05 wt. % to about 0.5 wt. %, the C2-C4 polyol in an amount ranging from about 0.02wt. % to about 0.1 wt. %, the water in an amount ranging from about 95 wt. % to about 99 wt. %, the fumed silica is present in an amount ranging from about 0.0002 wt. % to about 0.001 wt. % and the pH sensitive hydrogel forming polymer is present in an amount ranging from about 0.0002 wt. % to about 0.001 wt. %. .

9. The herbicide composition according to any one of claims 1 to 8, wherein the pH sensitive hydrogel forming polymer comprises the polymerised residues of acrylic acid and optionally one or more alkyl acrylates.

10. The herbicide composition according to any one of claims 1 to 9 further comprising a terpene.

11. The herbicide composition according to claim 10 when dependent on claim 7, wherein the terpene is present in an amount ranging from about 0.5 wt. % to about 2.5 wt. %.

12. The herbicide composition according to claim 10 when dependent on claim 8, wherein the terpene is present in an amount ranging from about 0.005 wt. % to about 0.1 wt. %.

13. The herbicide composition according to claim 10, 11 or 12, wherein the terpene is selected from pinene, nerol, citral, menthol, limonene, careen, cineol, camphene, dipentene, terpinolene and combinations thereof.

14. The herbicide composition according to any one of the preceding claims, wherein the Ce- C 12 fatty acid is selected from caproic acid, enanthic acid, caprylic acid, nonanoic acid, capric acid, sebacic acid, undecylic acid and lauric acid.

15. The herbicide composition according to any one of the preceding claims, wherein the Ce- C12 fatty acid comprises nonanoic acid and the C2-C4 polyol comprises propylene glycol.

16. A method of killing a plant or retarding its growth, the method comprising contacting the plant with a herbicide composition according to any one of the preceding claims.

17. A method of preparing a herbicide composition, the method comprising: providing a hydrogel composition, the hydrogel composition comprising fumed silica, C2-C4 polyol and alkyl polyglycoside dispersed throughout a pH sensitive hydrogel forming polymer that is at a pH to present in the form of a hydrogel polymer; and combining the hydrogel composition with C6-C12 fatty acid to provide for the herbicide composition, wherein the so formed herbicide composition has a pH at which the pH sensitive hydrogel forming polymer is not in the form of a hydrogel polymer.

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