WO2019244088A1

WO2019244088A1 - Agrochemical composition comprising a pyrimidyloxybenzoate in a synergistic combination with sulfonylureas

Info

Publication number: WO2019244088A1
Application number: PCT/IB2019/055195
Authority: WO
Inventors: Abid Ali ALAMSHAH; Ashim Kumar Dutta; Hagalavadi M VENKATESHA; Vishwanath GADE; Santosh Shridhar AUTKAR; Shailendra Mitharam Bharambe
Original assignee: Pi Industries Ltd.
Priority date: 2018-06-21
Filing date: 2019-06-20
Publication date: 2019-12-26

Abstract

The present invention provides a synergistic herbicidal combination and its composition comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, and method of preparation, and use thereof as herbicides for the control of weeds in agricultural crops, in particular the weed flora in rice as well as protecting crops from herbicidal injury caused by any of the individual components.

Description

TITLE: Agrochemical composition comprising a Pyrimidyloxybenzoate in a Synergistic Combination with Sulfonylureas

FIELD OF THE INVENTION:

The present invention relates to an herbicidal combination and its compositions. Particularly, the present invention relates to an herbicidal composition comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, methods of preparation of said composition and use thereof as herbicides for the control of weeds in agricultural crops.

BACKGROUND OF THE INVENTION:

Weeds cause damage to agricultural crops and adversely affect crop productivity by competing with the crop for mineral nutrients, nitrogen, water and sunlight. Several herbicides and method of using such herbicides to control the weed species are known in the prior art. Chemical herbicides are typically categorized according to the time of application (e.g., pre-emergence or post-emergence herbicides). Pre-emergence herbicides are applied prior to germination of weed for control of germinating seeds without harming the desired plant species. Post emergence herbicides are effective against the weeds that have already emerged from the grounds and are applied on the leaves during growth of such weeds to have an herbicidal effect and leave little residual action in the soil.

The herbicides or combination of herbicides can be applied in different ways, for example, sequential application, tank-mix application and premix application. In sequential application, farmers use different herbicides, wherein the herbicide selection is often not based on the technical know-how. As a consequence, herbicides having the same mode of action contribute to resistance development. In tank-mix applications, farmers use different combinations of herbicides, most of the times without having the training to properly mix appropriate products. Homemade tank mixes may therefore not be as stable as a premix. In such cases, the tank-mix application usually results in non-judicious use of individual herbicides and end up with poor weed control. Moreover, the tank mixture is less convenient and potentially hazardous to people who are not trained to properly mix the products. Pyrimidinyloxybenzoate represents an herbicidal class, which is a broad spectrum systemic herbicide for all types of rice cultivation, i.e. directs sown rice, rice nursery and transplanted rice. The best example of this class is bispyribac described inter alia in EP321846. Chemically, bispyribac is 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid and has the following structure:

Exemplary uses of bispyribac are described in The Pesticide Manual, Fifteenth Edition, 2009 and include, but are not limited to, the control of many grasses, sedges and broadleaf weeds, especially Echinochloa spp., in direct-seeded rice, as well to stunt the growth of weeds in non crop situations. Exemplary chemical forms of bispyribac include, for example, bispyribac - sodium, which is sodium 2,6-bis((4,6-dimethoxy pyrimidin-2-yl)oxy)benzoate and has the following structure:

Metsulfuron methyl and chlorimuron ethyl are candidates of the sulfonylureas chemical class. Chemically, metsulfuron methyl is methyl 2-(N-((4-methoxy-6-methyl-1 ,3,5-triazin-2- yl)carbamoyl)sulfamoyl)benzoate that inhibits the acetolactate synthase (ALS) in plants as described in US4394506 (A) and has the following structure:

Its herbicidal activity is exemplified in The Pesticide Manual, Fifteenth Edition, 2009. Metsulfuron-methyl is used to control grass and broadleaf weeds in wheat, barley, rice, oats and triticale.

Chemically, chlorimuron ethyl is ethyl 2-(N-((4-chloro-6-methoxypyrimidin-2- yl)carbamoyl)sulfamoyl)benzoate that inhibits the acetolactate synthase (ALS) in plants as described in US4547215 (A) and has the following structure:

Chlorimuron ethyl can be used, for post-emergence control of important broadleaf weeds, such as cocklebur, pigweed, sunflower, annual morning glory and other broadleaf weeds in rice, soybeans and peanuts in post-emergence conditions. Its herbicidal activity is described in The Pesticide Manual, Fifteenth Edition, 2009.

Various publications discloses the mixture of bispyribac sodium with a premix of chlorimuron ethyl and metsulfuron methyl used to control weeds, grasses or sedges in rice crop plants as described in literature, e.g. A. Hossain et al., Indian Journal of Weed Science; 46(3):220-223, 2014; Meera V. Menon et al., Journal of Tropical Agriculture, 52(2):204-208, 2016; K. Sreelakshmi et al., Indian Journal of Weed Science 48(1 ): 60-63, 2016; A. R. Sharma and D. Badiyala, 31 st annual progress report, All India Coordinated Research Programme on Weed Management, Jan-Dec 2014; ICAR Annual report (Apr 2016-1 7, Page 78-79); Shaik A. Meera et al. ICAR Frontline Demonstrations on Rice, 2017-18 and Dr. Virendra Pratap Singh, Directorate of weed science research, Pantanagar, 35^th Annual report, 2013. EP3207800 teaches the combination of bensulfuron methyl, metsulfuron methyl with a third herbicide as fluroxypyr for the treatment of weeds in rice crop plants.

The sequential application and tank-mix application of herbicides, when employed to address the weed flora in rice, is known to result in the development of herbicide resistance. The tank mix application of the active ingredients leads to the unequal distribution of the active components and incompatibility problems. It has been found that, as a solution to the above mentioned problems, an herbicidal composition containing bispyribac sodium, metsulfuron methyl and chlorimuron ethyl provides synergies in controlling weeds of rice crop and also contributes to the herbicide resistance management.

SUMMARY OF THE INVENTION:

In one aspect, the present invention provides a synergistic herbicidal combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, wherein optionally, an addition of one or more safener(s) or herbicidal or insecticidal or fungicidal or acaricidal or nematicidal compounds or any combination thereof.

In another aspect, the present invention provides the use of a synergistic herbicidal combination comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl for the control of a wide variety of harmful weeds in agricultural crops, in particular the weed flora in the rice crop.

As a further aspect, the present invention provides a synergistic herbicidal combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl that efficaciously contribute to the herbicide resistance management.

In one aspect, the present invention provides a synergistic herbicidal composition comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, wherein optionally, addition of one or more safener(s) or insecticidal or fungicidal or acaricidal or nematicidal compounds or any combinations thereof are possible.

In a particular aspect, the present invention provides a synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl, chlorimuron ethyl and agriculturally acceptable additives wherein the weight percentage of bispyribac sodium is 0.5% to 70%, the weight percentage of metsulfuron methyl is 0.5% to 20%, the weight percentage of chlorimuron ethyl is 0.5% to 20% and the weight percentage of additives is 1 % to 90%.

In a particular aspect, the present invention provides synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl, chlorimuron ethyl and agriculturally acceptable additives wherein the weight percentage of bispyribac sodium is 1 0% to 50%, the weight percentage of metsulfuron methyl is 0.5% to 5%, the weight percentage of chlorimuron ethyl is 0.5% to 5% and the weight percentage of additives is 40% to 90%.

In a further aspect, the present invention provides a synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl formulated as selected from a wettable powder (WP), a water dispersible granule (WG) or an oil dispersion (OD) composition.

In another aspect, the present invention provides a method for the preparation of the composition comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl.

In yet another aspect, the present invention provides a synergistic herbicidal composition comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl for the control of a wide variety of harmful weeds in agricultural crops, in particular the weed flora in the rice crop.

In one aspect, the present invention provides an herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl that efficaciously contribute to the herbicide resistance management.

In another aspect, the present invention provides an herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl that show technical advancement compared to existing herbicides or combination of herbicides.

In a further aspect, the present invention provides a synergistic herbicidal combination and its composition which meets the environmental and economic requirements imposed on modern- day herbicides, which are continually increasing, for example, with regard to the spectrum of action, toxicity, selectivity, application rate, formation of residues, low costs and favorable preparation ability.

The above aspects and other objectives will become more apparent in view of the description given below.

DETAILED DESCRIPTION OF THE INVENTION:

ABBREVIATIONS

DEFINITIONS

The foregoing definitions provided herein for the terminologies used in the present disclosure are for illustrative purpose only and in no manner limit the scope of the present invention disclosed in the present disclosure.

It will be understood that the terminology used herein is for the purpose of describing embodiments only, and is not intended to be limiting. As used in this specification, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, the reference to "a surfactant" includes one or more of such surfactants.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one ordinarily skilled in the art to which the invention pertains. Although other methods and materials similar, or equivalent, to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.

As used herein, the terms "comprises", "comprising", "includes", "including", or any other variation thereof, are intended to cover a non-exclusive inclusion, subject to any limitation explicitly indicated. For example, a composition or a method that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition or method.

As used herein, the term“composition” or "formulation" can be used interchangeably, unless stated otherwise, is meant to encompass, and are not limited to, compositions or formulations containing the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl.

As used herein, the term“additive(s)” refers to inert substances which are commonly used as diluent, to provide stability or to increase the activity profile of the composition or formulation with or without having agrochemical activity or direct effect on the undesired weeds.

As used herein, the term“surfactant(s)” means a compound that, when dissolved in a liquid, reduces the surface tension of the liquid, which reduces the interfacial tension between two liquids or which reduces surface tension between a liquid and a solid.

As used herein, the term“stabilizer(s)” refers to a substance capable of imparting resistance against physical or chemical deterioration or deformulation.

As used herein, the term“defoaming agent(s)” refers to a chemical additive that reduces and hinders the formation of foam in the industrial process of liquids, semi-solids, or solids. The terms defoaming agent and anti-foaming agent can be used interchangeably.

As used herein, the term “thickener(s)” refers to a polymeric material, which at a low concentration increases the viscosity of an aqueous solution and helps to stabilize the composition.

Unless otherwise specified, % refers to % weight; and % weight refers to % of the weight of the respective component with respect to the total weight of the composition.

As used herein, the term "effective amount" means the amount of the active substances in the compositions to achieve an observable effect on growth, including the effects of necrosis, death, retardation, prevention, and removal, destruction, or otherwise diminishing the occurrence and activity of the target weed. The effective amount can vary for the various compositions used in the present invention. An effective amount of the compositions will also vary according to the prevailing conditions such as desired herbicidal effect and duration, weather, target species, locus, mode of application, and the like.

As used herein, the term“bispyribac” encompasses bispyribac or its agrochemically acceptable salt(s) such as bispyribac sodium, ester(s), derivative(s) or any other modified form of bispyribac.

As used herein, the term “metsulfuron” encompasses metsulfuron or its agrochemically acceptable salt(s), ester(s) such as metsulfuron methyl, derivative(s) or any other modified form of metsulfuron.

As used herein, the term “chlorimuron” encompasses chlorimuron or its agrochemically acceptable salt(s), ester(s) such as chlorimuron ethyl, derivative(s) or any other modified form of chlorimuron.

The term herbicide, as used herein, means an active ingredient that kills, controls or otherwise adversely modifies the growth of plants. Herbicidally effective or vegetation controlling amount is an amount of one or more active ingredient which causes an adversely modifying effect and includes deviations from natural development, killing, regulation, desiccation, retardation and the like. The terms plants, weeds and vegetation include germinant seeds, emerging seedlings, plants emerging from vegetative propagules and established vegetation.

The term synergistic, as used herein, means an interaction of two or more factors such that the effect when combined is greater than the predicted effect based on the response to each other when applied individually.

Accordingly, the present invention provides a synergistic herbicidal combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, wherein optionally, an addition of one or more safener(s) or herbicidal or insecticidal or fungicidal or acaricidal or nematicidal compounds or any combination thereof is possible.

In one embodiment, the present invention provides an herbicidal combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl for the management of the weed flora in the rice crop. In another embodiment, the present invention of an herbicidal combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl is effective in the management of post-emergence of numerous monocotyledonous and dicotyledonous weeds.

In one embodiment, the present invention provides a synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl.

In another embodiment, the present invention provides an herbicidal composition of bispyribac sodium, metsulfuron methyl, chlorimuron ethyl and agriculturally acceptable additives wherein the weight percentage of bispyribac sodium is 0.5% to 70%, the weight percentage of metsulfuron methyl is 0.5% to 20%, the weight percentage of chlorimuron ethyl is 0.5% to 20% and the weight percentage of additives is 1 % to 90%.

In a further embodiment, the present invention provides a synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl for the management of the weed flora in the rice crop.

In another embodiment, the present invention of a synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl is effective in the management of post-emergence of numerous monocotyledonous and dicotyledonous weeds.

The composition of the present invention comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl can be mixed in a wide ratio, in relation to various factors such as, the weeds to be controlled, the degree of infestation, the climatic conditions, the characteristics of the soil and the application method.

In an embodiment, the present invention provides a synergistic herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl. The composition is selected from wettable powder (WP), a water dispersible granule (WG), a water dispersible tablet (WT), a suspension concentrate (SC), an ultra-low volume (ULV) liquid (UL), an ultra-low volume (ULV) suspension (SU), a water soluble powder (SP), a soluble concentrate (SL), a water soluble granule (SG), granule (GR), an emulsifiable concentrate (EC), an oil dispersion (OD), a dustable powder (DP) or an aerosol (AE). These compositions may be manufactured by any process known in the art, such as,“Pesticide Formulation Guide” (edited by the Pesticide Science Society of Japan, The Agricultural Formulation and Application Committee, published by the Japan Plant Protection Association, 1997).

In a preferred embodiment, herbicidal composition of the combination of bispyribac sodium, metsulfuron methyl, chlorimuron ethyl and agriculturally acceptable formulation additives in the weight percentage of bispyribac sodium is 10% to 50%, the weight percentage of metsulfuron methyl is 0.5% to 5%, the weight percentage of chlorimuron ethyl is 0.5% to 5% and the weight percentage of additives is 40% to 90%.

The composition comprising organic or inorganic carrier material, including agriculturally acceptable additive(s) is selected from the group comprising of solid carrier(s), liquid carrier(s), gaseous carrier(s), surfactant(s), binder(s), disintegrating agent(s), pH adjuster(s), thickener(s), preservative(s), anti-freezing agent(s), defoaming agent(s), extender(s), stabilizer(s) and/or coloring agent(s) or a combination thereof. The composition may also contain if desired, one or more auxiliaries customary for crop protection compositions.

Solid carrier(s) is selected from the group comprising of, but not limited to, natural minerals such as quartz, talc, kaolin, pyrophyllite, montmorillonite, attapulgite, bentonite, chalk, zeolite, calcite, sericite, acid clay, diatomaceous earth, Fuller’s earth, meerschaum, gibbsite, dolomite or pumice; synthetic minerals such as precipitated silica, fumed silica, sodium silicate, alumina, aluminum hydroxide; inorganic salts such as calcium carbonate, ammonium sulfate, sodium sulfate, potassium chloride, organic materials such as urea, solid polyoxyethylene, solid polyoxypropylene, polyethylene, polypropylene, lactose, starch, lignin, cellulose, cottonseeds hulls, wheat flour, soyabean flour, wood flour, walnut shell flour, plant powders, sawdust, coconut shellflower, corn cob, tobacco stem. These solid carriers may be used alone or in combination.

Liquid carrier(s) is selected from the group comprising of, but not limited to, water; alcohols such as ethanol, propanol, n-octanol, isopropanol ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerin; polyol ethers such as ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, dipropylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; ethers such as dipropyl ether, dioxane, tetrahydrofuran, aliphatic hydrocarbons such as normal paraffin, isoparaffin, kerosene, mineral oil; aromatic hydrocarbons such as xylene, toluene, naphthene, solvent naphtha, solvent C9, solvent C10, solvent C12, solvesso 100, solvesso 1 50, solvesso 200; chlorinated aliphatic or aromatics hydrocarbons such as chlorobenzene, chloroethylene, methylene chloride; esters such as ethyl acetate, diisopropyl phthalate, dimethyl adipate, methyl oleate, methyl tallowate; lactones such as gamma-butyrolactone, gamma-valerolactone, epsilon-caprolactone; amides such as dimethylformamide, N-methylpyrrolidone, N-octylpyrolidone, N,N-dimethyldecanamide; nitriles such as acetonitrile; organosulfur compound such as dimethyl sulfoxide; vegetable oils such as soybean oil, rapeseed oil, cotton seed oil. These liquid carriers may be used alone or in combination.

Gaseous carrier(s) is selected from the group comprising of, but not limited to, liquefied petroleum gas, air, nitrogen, carbon dioxide or dimethyl ether. These gaseous carriers may be used alone or in combination thereof.

Surfactant(s) (a dispersing agent, a wetting agent, a spreader, an adjuvant for penetration enhancement, rain fastness, soil leaching control etc.) are nonionic or anionic surfactants or a combination of these surfactants. It is preferred to use one or more than one kind of surfactant. Surfactant(s) is selected from the group comprising of, but not limited to, sugar esters such as sorbitan monolaurate, polyoxyethylene sorbitan monolaurate; alkyl polyglucoside such as decyl glucoside; polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, or polyoxyethylene coconut fatty alcohol ether; polyoxyethylene alkynyl ether such as polyoxyethylene 2,4,7,9-tetramethyl-5-decyn-4,7-diol ether; polyoxyethylene aryl ethers such as polyoxyethylene nonylphenyl ether or polyoxyethylene tristyrylphenyl ether; polyoxyethylene vegetable oil ethers such as polyoxyethylene castor oil or polyoxyethylene hydrogenated castor oil; polyoxyethylene fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene distearate or polyoxyethylene resin acid ester; polyoxyethylene polyoxypropylene block co polymers such as Pluronic^®; polyoxyethylene polyoxypropylene alkyl ether such as polyoxyethylene polyoxypropylene lauryl ether; polyoxyethylene polyoxypropylene aryl ether such as polyoxyethylene polyoxypropylene styrylphenyl ether; polyoxyethylene alkyl amines such as polyoxyethylene stearyl amine; polyoxyethylene fatty acid amide such as lauric acid diethanolamid; fluorinated surfactant; alkyl sulfates such as sodium lauryl sulfate; sodium alkylbenzene sulfonate; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate; polyoxyethylene aryl ether sulfates such as sodium polyoxyethylene nonylphenyl ether sulfate or ammonium polyoxyethylene tristyrylphenyl ether sulfate; aryl sulfonate such as calcium dodecyl benzene sulfonate, sodium naphthalene sulfonate or sodium naphthalene sulfonate formaldehyde condensate; ‘alpha’-olefin sulfonate; alkyl sulfosuccinate such as sodium dioctyl sulfosuccinate; sodium lignosulfonate; polycarboxylic acid sodium salt; N-methyl fatty acid sarcosinate; polyoxyethylene alkyl ether phosphate; polyoxyethylene aryl ether phosphates such as polyoxyethylene phenyl ether phosphate; polyoxyethylene alkyl phenyl ether phosphate; graft co-polymers such as polymethyl methacrylate-polyethylene glycol graft copolymer; or a combination thereof.

Binder(s) or adhesive-imparting agent(s) is selected from the group comprising of, but not limited to, polyvinyl alcohol, dextrin, denatured dextrin, soluble starch, guar gum, xanthan gum, sucrose, polyvinylpyrrolidone, gum arabic, polyvinyl acetate, sodium polyacrylate, carboxymethyl cellulose or its salt, carboxymethylcellulose dextrin, bentonite, polyethylene glycol having an average molecular weight of 6,000 to 20,000, polyethylene oxide having average molecular weight of 100,000 to 5,000,000, natural phosphatide such as cephalinic acid or lecithin. These binders or adhesive-imparting agents may be used alone or in combination thereof.

Disintegrating agent(s) is selected from the group comprising of, but not limited to, sodium tripolyphosphate, stearic acid metal salt, cellulose powder, dextrin, methacrylate co-polymer, polyvinylpyrrolidone, polyaminocarboxylic acid chelate compound, styrene sulfonate/isobutylene/maleic anhydride co-polymer, starch/polyacrylonitrile graft co-polymer, sodium hexametaphosphate, carboxymethyl cellulose, sodium polycarbonate, bentonite. These disintegrating agents may be used alone or in combination thereof. pH adjuster(s) is selected from the group comprising of, but not limited to, sodium or potassium carbonate, sodium or potassium hydrogen carbonate, sodium or potassium dihydrogenphosphate, disodium or dipotassium hydrogenphosphate, citric acid, malic acid and triethanolamine. These pH adjusters may be used alone or in combination thereof.

Thickener(s) is selected from the group comprising of, but not limited to, water-soluble polymer and inorganic fine powder, wherein the examples for water-soluble polymers are xanthan gum, welan gum, guar gum, polyvinyl alcohol, carboxymethylcellulose, polyvinylpyrrolidone, carboxyvinyl polymer, acrylic polymer, starch derivative or polysaccharide; or an inorganic fine powder selected from high purity silica, bentonite, white carbon. These thickeners may be used alone or in combination thereof.

Preservative(s) is selected from the group comprising of, but not limited to, potassium sorbate, 4-hydroxybenzoic acid esters, 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3- one, 1 ,2-benzisothiazolin-3-one (Proxel^® GXL). These preservatives may be used alone or in combination thereof.

Anti-freezing agent(s) is selected from the group comprising of, but not limited to, polyhydric alcohol such as ethylene glycol, diethylene glycol, propylene glycol, and glycerol. These anti freezing agents may be used alone or in combination thereof.

Defoamer(s) is selected from the group comprising of, but not limited to, silicone compounds such as polysiloxane, polydimethyl siloxane and organic fluorine compounds. These defoaming agents may be used alone or in combination thereof.

Extender(s) is selected from the group comprising of, but not limited to, silicon type surfactant, a cellulose powder, dextrin, processed starch, a polyaminocarboxylic acid chelate compound, crosslinked polyvinylpyrrolidone, maleic acid and styrene, methacrylic acid co-polymer, half ester of polymer of polyhydric alcohol with dicarboxylic anhydride, water-soluble salt of polystyrene sulfonic acid. These extenders may be used alone or in combination thereof.

Stabilizer(s) is selected from the group comprising of, but not limited to, drying agent such as zeolite, quick lime or magnesium oxide; antioxidant agent such as phenol type, amine type, sulfur type or phosphorus type; or ultraviolet absorber such as salicylic acid type or a benzophenone type. These stabilizers may be used alone or in combination thereof.

Coloring agent(s) is selected from the group comprising of, but not limited to, inorganic pigment such as iron oxide, titanium oxide or Prussian blue; organic dye such as alizarin dye, azo dye, metal phthalocyanine dye. These coloring agents may be used alone or in combination thereof. When additive ingredients are incorporated into the composition of the present invention, the content of the carrier is selected typically in weight range from 5% to 95%, preferably from 20% to 90%; the content of the surfactant is selected from the range of typically from 0.1 % to 30 %, preferably from 0.5% to 10%, and the content of the other additives is selected from the range of typically from 0.1 % to 50%.

The composition of the present invention can be applied by any one of the methods selected from atomization, spreading, dusting, spraying, diffusion, immersion, irrigation, injection, mixing, sprinkling (water immersion), foaming, dressing, coating, blasting, fumigation, smoking, smog and painting.

In an embodiment, the composition of the present invention may be used in the form of a single package formulation for premix application containing bispyribac sodium, metsulfuron methyl and chlorimuron ethyl together with agriculturally acceptable additives.

The composition of the present invention may be in the form of a two package formulation, wherein one package contains a composition of bispyribac sodium while the other package contains a composition of metsulfuron methyl and chlorimuron ethyl, wherein both formulations contain agriculturally acceptable additives for crop protection. In the case of two package formulations, one package contains the composition of bispyribac sodium and other package contains the composition of metsulfuron methyl and chlorimuron ethyl and is mixed prior to application.

In an embodiment, the composition of the present invention comprises bispyribac sodium, metsulfuron methyl, chlorimuron ethyl, optionally addition of one or more safener or herbicidal or insecticidal or fungicidal or acaricidal or nematicidal compound or any combinations thereof, and additives to form different types of compositions selected from, but not limited to, a wettable powder (WP), a water dispersible granule (WG), an oil dispersion (OD) and the like.

In a preferred embodiment, the present invention provides a synergistic herbicidal composition of the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl.

In another embodiment, the present invention provides an herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, with one or more herbicidal compounds but not limited to fenoxaprop-p-ethyl, diclosulam, metamifop, cyhalofop-butyl, azimsulfuron, carfentrazone. In a further embodiment, the present invention provides herbicidal composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl, with one or more insecticidal or fungicidal or acaricidal or nematicidal compounds or any combination thereof.

Another embodiment of the present invention provides a synergistic herbicidal composition, which comprises:

(i) addition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl,

(ii) at least one inert agriculturally acceptable adjuvant or carrier,

(iii) optionally, addition of one or more safener,

(iv) optionally, addition of one or more herbicidal or insecticidal or fungicidal or acaricidal or nematicidal compound or any combination thereof.

The synergistic herbicidal composition described herein is employed in combination with known herbicide safeners which are selected from the group comprising of, but not limited to, benoxacor, benthiocarb, brassinolide, cloquintocet, cloquintocet-mexyl, cyprosulfamide, cyometrinil, diamuron, dichlormid, dicyclonon, dietholate, dimepiperate, disulfoton, fenclorim, fenchlorazole, fenchlorazole ethyl, furilazole, flurazole, fluxofenim, harpin proteins, isoxadifen- ethyl, mephenate, mefenpyr, mefenpyr-diethyl, metcamifen, MG 191 , AD-67 (MON 4660), R29148, BPCMS, jiecaowan, jiecaoxi, naphthalic anhydride, oxabetrinil, N-phenyl- sulfonylbenzoic acid amides, 1 -4-(N-(2-methoxybenzoyl)sulfamoyl) phenyl-3-methylurea, N-(2- methoxybenzoyl)-4-(methylaminocarbonyl)aminobenzenesulfonamide, to enhance their selectivity.

In a specific embodiment, a wettable powder composition is provided. The composition of wettable powder comprises of bispyribac sodium, metsulfuron methyl, chlorimuron ethyl, and agrochemically acceptable additives such as surfactant(s) and carriers. Other additives such as pH adjusters and colorants may be additionally used.

A method for preparing the wettable powder composition of the present invention is also provided. The wettable powder composition can be prepared by addition of the active ingredients, and agrochemically acceptable additives such as surfactant(s) and carriers. The bispyribac sodium, metsulfuron methyl, chlorimuron ethyl and agrochemically acceptable additives are mixed uniformly in a mixer and milled. Usually milling is carried out by a mill such as an air jet mill, to a median diameter of 1 to 50 miti, more preferably to a median diameter of 2 to 1 0 pm particle sizes.

A further embodiment of the present invention relates to a method of preparing a wettable powder composition, which comprises:

a) addition of bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl,

b) addition of agrochemically acceptable additives selected from surfactant(s), carrier(s) and other additive(s) uniformly in a mixer; and

c) optionally, milling by a mill.

The milling step in the wettable powder formulation is carried out by an air jet mill to a median diameter of 2 to 10 pm particle sizes.

Another embodiment of the present invention provides a water dispersible granule composition. The water dispersible granule composition comprises of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl as active ingredients, and agrochemically acceptable additives such as surfactant(s), binder(s), disintegrating agent(s) and carrier(s). Other additives such as pH adjuster(s) and colorant(s) may be additionally used.

A method for preparing the water dispersible granule composition of the present invention is also provided. A water dispersible granule composition can be prepared by addition of the active ingredients, and agrochemically acceptable additive(s) such as surfactant(s), binder(s), disintegrating agent(s) and carrier(s). The active ingredients and agrochemically acceptable additives are mixed uniformly in a mixer and milled. Usually milling is carried out by a mill such as an air jet mill to a median diameter of 1 to 50 pm, more preferably to a median diameter of 2 to 10 pm particle sizes. The milled mixture is kneaded by adding 10% to 40% of water, extruded and dried. Other granulation methods such as spray dry or fluidized bed granulation may be used.

A further embodiment of the present invention relates to a method of preparing a water dispersible granule formulation, which comprises the steps of:

a) addition of carrier, bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl, b) addition of agrochemically acceptable additives such as surfactant(s), binder(s), disintegrating agent(s) and other additive(s) uniformly in a mixer; c) optionally, milling by a mill; and

d) water added to the mixture, granulated and dry the mixture.

The milling step in a water dispersible granule formulation is carried out by an air jet mill to a median diameter of 2 to 10 pm particle sizes.

In another embodiment of the present invention provides an oil dispersion formulation. An oil dispersion formulation comprises of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl as active ingredients, solvents (such as paraffinic solvent, aromatic solvent, vegetable oil or methylated seed oils) and surfactants. Other formulation additives such as thickener(s), preservative(s), anti-freezing agent(s), defoamer(s), pH adjuster(s) and colorant(s) may be additionally used.

A method for preparing an oil dispersion formulation of the present invention is also provided. An oil dispersion formulation can be prepared by wet milling of the active ingredients mixed with surfactants, solvents and other formulation additives. Usually the active ingredients and surfactant(s) are mixed by dissolving or dispersing them in a suitable medium such as paraffin oil. The mixture is preliminary milled by a homogenizer such as a colloid mill and then milled by a bead mill till median diameter of the particle reaches to 1 to 5 pm particle sizes.

Another embodiment of the present invention relates to a method for the preparation of an oil dispersion formulation, which comprises steps of:

a) addition of bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl into a mixture of solvents and surfactant(s),

b) addition of optional additive(s),

c) optionally, milling of the above obtained mixture.

The milling process comprises wet milling, preliminary milling by a homogenizer and then milling by a bead mill to achieve a median diameter of 1 to 5 pm particle sizes, wherein the homogenizer is a colloid mill.

In an embodiment, the present invention provides a method of controlling a wide variety of harmful weeds, with an effective amount of a composition of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl. The combination or composition of the present invention is suitable for controlling a large number of harmful weeds, including monocotyledonous weeds, in particular annual weeds, but not limited to, Echinochloa species such as barnyard grass ( Echinochloa crusgalli var. crus- galli), deccan grass ( Echinochloa colonum), hippo grass ( Echinochloa stagina)·, Digitaria species such as crabgrass ( Digitaria sanguinalis)·, Setaria species such as green foxtail ( Setaria viridis) and giant foxtail ( Setaria faberi) Sorghum species such as Johnson grass ( Sorghum halepense Pers.)·, Cenchrus species such as Cenchrus echinatus ; Avena species; Bromus species; Eriochloa species; Panicum species such as torpedo grass ( Panicum repens), fall panic grass ( Panicum dichotomiflorum)·, Brachiaria species; Phleum species; Festuca species; Lolium species; Agropyron species such as Agropyron repens Monochoria species such as Monochoria vaginalis·, Sagittaria species; Eleocharis species; Paspalum species; Ischaemum species such as Ischaemum rugosum·, Sphenoclea species such as Sphenoclea zeylanica·, Dactyloctenium species such as Dactyloctenium aegyptium·, Agrostis species; Poa species such as annual blue grass ( Poa annua)·, Alopecurus species such as black grass ( Alopecurus myosuroides)·, Aegilops cylindrica, Apera species such as Apera spica-ventr, Eleusine species such as Eleusine indica Cynodon species such as Cynodon dactylon: Leptochola chinensis: Cyanotis axillaris and the like.

The combination or composition of the present invention is also suitable for controlling a large number of dicotyledonous weeds, including but not limited to, Eclipta alba·, Ludwigia parviflora·, Ammannia baccifera·, Physalis minima·, Alternanthera species such as Alternanthera philoxeroides·, Solanum species; Euphorbia species; Sinapis species; Cassia species; Amaranthus species such as pigweed ( Amaranthus retroflexus)·, Sida species such as prickly sida ( Sida spinosa L); Ambrosia species such as common ragweed (Ambrosia artemisiifolia)·, Acanthospermum species; Anthemis species; Atriplex species; Cirsium species; Conyza species; Commelina species such as wandering jew ( Commelina benghalensis), spreading dayflower ( Commelina diffusa)·, Datura species; Geranium species; Galinsoga species; Ipomoea species; Lamium species; Matricaria species; Sysimbrium species; Xanthium species; Veronica species; Viola species; Sinapsis species; Lepidium species; Galium species; Stellaria species such as common chickweed ( Stellaria media)·, Chenopodium species; Urtica species; Senecio species; Portulaca species; Convolvulus species; Polygonum species; Carduus species; Sonchus species; Rorippa species; Rotala species; Lindernia species; Emex species; Galeopsis species; Papaver species; Centaurea species; Trifolium species; Ranunculus species; Taraxacum species; Abutilon species such as velvetleaf ( Abutilon theophrasti ); Bergia species such as Bergia capensis Sesbania species such as Hemp sesbania ( Sesbania exaltata Cory)·, stone breaker ( Phyllanthus niruri) ; toothache plant ( Spilanthus acmella)·, Indian jointvetch ( Aeschynomene indica)·, white weed ( Ageratum conyzoides)·, pink node flower ( Caesulia axillaris) and the like.

The combination or composition of the present invention is also suitable for controlling a large number of annual and perennial sedge weeds including Cyperus species such as purple nut sedge ( Cyperus rotundus L.), yellow nut sedge ( Cyperus esculentus L.), hime-kugu ( Cyperus brevifolius hi , sedge weed ( Cyperus micro-iria Steud), rice flat sedge ( Cyperus iria L.), smallflower umbrella-sedge ( Cyperus difformis L.), Fimbristylis species such as Fimbristylis miliacea·, Scirpus species and the like.

The herbicidal combination or composition comprising of bispyribac sodium and metsulfuron methyl, chlorimuron ethyl exhibits a synergistic action in the control of a variety of weeds, selected from Echinochloa species ( Echinochloa colonum, Echinochloa crus-galli), Physalis species ( Physalis minima), Phyllanthus species ( Phyllanthus niruri), Leptochola species ( Leptochola chinensis), Ludwigia species ( Ludwigia parvifiora), Commelina species ( Commelina benghalensis) Cyperus species ( Cyperus iria, Cyperus difformis), Fimbristylis species (Fimbristylis miliacea), or Eclipta species ( Eclipta alba).

In an embodiment of the present invention, the combination or its composition exhibit safening activity in a variety of crops, including but not limited to, rice, wheat, sugarcane, corn, maize, rye, sorghum, pastures, grasslands, rangelands, fallowland, non-cropland, turf, industrial vegetation management (IVM) and aquatics, as well as protecting crops from herbicidal injury caused by any of the individual components. The combination or its composition of the present invention in particular is suitable for controlling weeds of rice crop (Nursery, direct seeded rice as well as transplanted rice). The combination or its composition can be applied post-emergence, i.e. after the emergence of the weeds.

The combination or composition of the present invention can also be used to control harmful plants in crops of genetically modified plants. The combination or composition of the present invention can be used in transgenic crops which are resistant to growth regulators such as, dicamba, or to herbicides, which inhibit essential plant enzymes, for example acetolactate synthases (ALS), 5-enolpyruvylshikimate-3-phosphate (EPSP) synthases, glutamine synthases (GS) or hydroxyphenylpyruvate dioxygenases (HPPD), or to herbicides from the group of sulfonylureas, glyphosates, glufosinates or benzoylisoxazoles and analogous active compounds.

It is a particular benefit of the combination according to the present invention that they have a very good post-emergence herbicidal activity. Thus, in a preferred embodiment of the invention, the combination or its composition is applied in a post-emergence model, i.e. during and/or after, the emergence of the weeds. It is particularly advantageous to apply the combination according to the invention in a post-emergence model when the weeds start with leaf development up to flowering. Since this combination or its composition shows good crop tolerance, it can be applied after seeding of the crop plants and in particular during or after the emergence of the crop plants. The present invention is further illustrated by the following examples. These examples describe possible preferred embodiments for illustrative purposes only, but they do not limit the scope of the invention.

Example 1 : Instant Formulation

Preparation method:

Compounds were dissolved in 2% dimethyl sulfoxide and then mixed with water to calibrated the spray volume of 50 ml / sqmt; to this 0.1 % silwet (silica based wetting agent) was added.

Example 2: Wettable Powder (WP):

Preparation method:

Bispyribac sodium technical 38.78 parts and sodium sulfate 10.00 parts were put into kaolin clay 39.04 in a high shear mixer and mixed well. The mixture of bispyribac sodium technical, sodium sulfate and kaolin clay was added with chlorimuron ethyl technical 2.58 parts, metsulfuron methyl technical 2.60 parts, sodium alkyl sulfate 1 .5 parts, sodium lignosulfonate 4.00 parts, modified styrene acryl polymer 1 .00 parts and fumed silica 0.5 parts and mixed well. The mixture was milled by an air jet mill to get a mass median diameter 2 to 1 0 pm which is post- blended to yield the wettable powder (WP) composition.

Example 3: Water dispersible granule (WG):

Preparation method:

Bispyribac sodium technical 38.78 parts and ammonium sulfate 10.00 parts were put into kaolin clay 37.04 parts in a high shear mixer and mixed well. The mixture of bispyribac sodium technical, sodium sulfate and kaolin clay was added with chlorimuron ethyl technical 2.58 parts, metsulfuron methyl technical 2.60 parts, sodium alkyl sulfate 1 .5 parts, sodium lignosulfonate 5.00 parts, modified styrene acryl polymer 2.00 parts and fumed silica 0.5 parts and mixed well. The mixture was milled by an air jet mill to get a mass median diameter of 2 to 10 pm which is post-blended. Thereafter, water 32 parts were added into the homogenous mixture, and mixed well in a versatile mixer. The wetted mixture was granulated by a basket type extruder through a 1 .0 mm screen, dried in a fluidized bed dryer, sized and sieved to yield the water dispersible granule (WG) composition.

Example 4: Oil dispersion (OD):

Preparation method:

Bispyribac sodium technical 19.39 parts, chlorimuron ethyl technical 1 .29 parts and metsulfuron methyl technical 1 .30 parts were put into a mixture of alkyl ethoxylate (high HLB) 22.5 parts, alkyl ethoxylate (low HLB) 37.50 parts, sorbitan ester ethoxylate 8.00 parts and paraffin oil 10.2 parts and milled in a colloidal mill to get a mass median diameter below 1 00 pm. Thereafter, the mixture was milled by a bead mill to get a median diameter of 1 to 5 pm to yield the oil dispersion (OD) composition.

The herbicidal composition according to the present invention does not show phytotoxicity with respect to rice, sugarcane, cereal and grain crops, pastures, rangelands, industrial vegetation management (IVM), aquatics and turf. This results in the composition of the present invention being effective and selective in the management and control of weeds.

The application rate of the herbicide components and their derivatives in herbicidal composition may vary within wide ranges. The application rates (g a.i. /ha) of the herbicide components in the herbicidal composition are in the weight ratios (bispyribac sodium): (metsulfuron methyl): (chlorimuron ethyl) as stated below:

• Generally (1 -2000) : (1 -200) : (1 -200) • Preferably (1 -100): (1 -10): (1 -10)

• Particularly preferably (1 -30): (1 -5): (1 -5)

The herbicidal combination or its composition for the weed control for the crop such as rice is advantageous, for several purposes, e.g.:

• allowing for a wider application window such as greater flexibility in the timing of application spanning over 7 to 28 days after sowing;

• having synergistic effect being useful for addressing a broad weed spectrum;

• requiring to be administered in lower dosage strength and lower dosage frequency;

• being useful for post-emergence control of a number of both monocot and dicot weed species with a single application of the synergistic combination;

• offering a single solution for different rice cultivation segments such as nursery, transplanted, direct seeded rice with a wider application window.

Thus, from the foregoing description, it will be apparent to one of ordinary skilled in the art that many changes and modifications can be made thereto, without departing from the spirit or scope of the invention as set forth in the claims. Accordingly, it is not intended that the scope of the foregoing description should be limited to the description set forth above, but rather that such description be construed as encompassing such features that reside in the present invention, including all the features and embodiments that would be treated as equivalents thereof by those skilled in the relevant art.

Following the test results illustrate the present invention and are not intended to limit the present invention.

Effect of Combination of Bispyribac sodium, Metsulfuron methyl and Chlorimuron ethyl

Greenhouse experiments were conducted to evaluate the efficacy of the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl. The target crop was rice and targeted weeds of rice were Echinochloa colonum, Echinochloa crus-galli, Leptochloa chinensis, Cyperus iria, Cyperus difformis, Fimbristylis miliacea, Eclipta alba, and Ludwigia parviflora. Bio efficacy was assessed by calculating the percent of weed control by Abbots formula. The treatment details are shown below in table 1 . Validation of invention Concept:

The above mentioned greenhouse studies were undertaken with the following objectives.

> To establish the synergistic action in terms of increased efficacy and broader spectrum over solo application for grasses, broad leaved weeds and sedges.

> To demonstrate the compatibility of the formulations in terms of physical appearance of the solution, coagulation, safety to crops, spray separator etc.

A. Effective dose:

Greenhouse trials were conducted to observe the efficacy of the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl against important weeds in rice. The combination was also evaluated in comparison to solo applications of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl and different two way mixture of formulation of bispyribac sodium and chlorimuron ethyl, formulation of bispyribac sodium and metsulfuron methyl, and formulation of metsulfuron methyl and chlorimuron ethyl. Weeds evaluated include Echinochloa colonum, Echinochloa crus-galli, Leptochloa chinensis, Cyperus iria, Cyperus difformis, Fimbristylis miliacea, Eclipta alba, and Ludwigia parviflora. Bio-efficacy, in terms of percent mortality of weeds 15 days after application, was taken up and is presented in Tables 3, 4 and 5.

It is shown in tables that the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl (20+1 .34+1 .34 g a.i ./ ha) was most effective treatment, providing an excellent efficacy on grasses, sedges and broad leaf weeds better than the solo applications of bispyribac sodium; metsulfuron methyl and chlorimuron ethyl and different two way mixture of formulation of bispyribac sodium and chlorimuron ethyl, formulation of bispyribac sodium and metsulfuron methyl, and formulation of metsulfuron methyl and chlorimuron ethyl.

B. Establishment of synergistic action:

Extensive literature survey and number of trials revealed that various herbicides from different groups are showing a synergistic effect rather than an additive or deleterious effect. Based on the literature available, various combinations of herbicides have been developed and globally used to combat many weeds. Such combinations also provide an enhanced spectrum of activity and delay resistance development for a longer period. Present greenhouse trials provide the evidence of a synergistic effect of the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl showing effective control on grasses, sedges and broad leaf weeds when compared to the solo applications of bispyribac sodium; metsulfuron methyl and chlorimuron ethyl and different two way mixture of formulation of bispyribac sodium and chlorimuron ethyl, formulation of bispyribac sodium and metsulfuron methyl, and formulation of metsulfuron methyl and chlorimuron ethyl.

C. Percentage of weed control for bio-efficacy:

Percent mortality of weeds 15 days after application was recorded and presented in Tables 3, 4 and 5. Phytotoxicity was also recorded which is presented in Table 6. Highest percentage of weed control and lower phytotoxicity were recorded in the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl. It is evident from the tables that the combination developed has good control of the weeds.

The treatment details are shown below in table 1 . The synergistic effect of the combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl is being evaluated in terms of weed control. The target crop is rice and targeted weeds of rice were Echinochloa colonum, Echinochloa crus-galli, Leptochloa chinensis, Cyperus iria, Cyperus difformis, Fimbristylis miliacea, Eclipta alba, and Ludwigia parviflora. Bio-efficacy was assessed by calculating the percentage of weed control by Abbots formula.

D. Compatibility of combination:-

Visual observation of the combination clearly indicated that all the three active ingredients are physically compatible and crop plants treated with the combination showed no plant damage. There were no signs of dermal or eyes, irritation effects observed. There was no phytotoxicity is observed. Phytotoxicity scale is shown below in Table 2 and the phytotoxicity results are shown below in Table 6.

The expected herbicidal action for the combination of three active ingredients can be calculated according to S. R. Colby (“Calculating Synergistic and Antagonistic Responses of Herbicide Combinations”, Weeds 1967, 15, 20-22), as follows:

Expected % weed control (E):

(AB + AC + BC) ABC

(E) = (A + B + C)— -— - - +

1 00 10,000 A= observed efficacy of active ingredient A at the same concentration as used in the mixture;

B= observed efficacy of active ingredient B at the same concentration as used in the mixture;

C= observed efficacy of active ingredient C at the same concentration as used in the mixture. Synergism of the mixture is determined by comparing observed response (O) of the mixture to the expected or predicted response (E) as calculated from the observed response of each individual component alone.

If the observed response of the mixture is greater than the expected or predicted response (E) then the mixture is said to be synergistic.

If E>0 then the result is antagonistic effect

If E=0 then its additional effect.

Table 1 : Treatment details for to assess the synergistic effect of the combination of Bispyribac sodium, Metsulfuron methyl and Chlorimuron ethyl.

Experimental Method: To evaluate the post emergence activity of the compounds, rice along with test weed seeds were sown in separate lines on loamy soil in plastic trays of (30cm (L) X 20cm (B) size) in the greenhouse. Plant thinning was done to maintain 20 plants in a row for each weed species and rice crop. Compounds were dissolved in 2% DMSO and then mixed with water to calibrated the spray volume of 50 ml; to this 0.1 % silvet (silica based wetting agent) was added. Post-emergence application of the treatment component as foliar spray was done when weeds were about 2-3 leaf stage (12 days after sowing) under saturated soil moisture conditions and the saturated soil moisture conditions were maintained throughout the experiment. Test compounds were sprayed at the test doses mentioned in the treatment details Table 1 , inside the Generation-3 spray cabinets using flat fan nozzles with 500 It. water volume per ha basis. The treatment was replicated thrice and the test plants were kept in the greenhouse till final observation with 25 ^° C temperature and 70% humidity. Efficacy in terms of percentage weed control was assessed 1 5 days after application (DAA) by calculating percentage of weed control in comparison with untreated control by Abbots formula. Phytotoxicity was recorded at 3, 7, 10 and 14 days after application on 0-10 scale as shown in table 2.

Abbots formula:

Where : n = Number of weed plant, T = treated, Co = control

Table 2: Phytotoxicity scale (0-10)

Table 3: Mean Percent grassy weed control of grassy weeds 15 DDA (days after application)

BS: Bispyribac sodium; MSM: Metsulfuron methyl; CME: Chlorimuron ethyl.

5 Table 4: Mean Percent weed control of broad leaved weeds 15 DDA (days after application)

5 Table 5: Mean Percent weed control of sedges 15 DDA (days after application)

BS: Bispyribac sodium; MSM: Metsulfuron methyl; CME: Chlorimuron ethyl.

Results: Metsulfuron methyl and chlorimuron ethyl or their combination was only effective against broad leaved weeds and sedges, and the grass control was poor. The test doses of metsulfuron methyl and chlorimuron ethyl alone or their combination did not improve the grass control. Bispyribac sodium at 20 and 25 g a.i. /ha was found effective against grasses, broad leaved weeds and sedges. Tank-mix combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl indicated synergistic effect in terms of improved efficacy against grasses, broad leaved weeds and sedges at doses 20+1 .34+1 .34 g a.i./ha. The combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl at a ratio of 1 :14.9:14.9 shows synergies in terms of weed control against grasses broad leaved weeds and sedges while and other ratios 1 :1 1 .9:1 1 .9, 1 :1 1 .9:14.9 and 1 :14.9:1 1 .9 indicated synergies on grass control only. The synergies were confirmed with Colby’s equation. Table 6: Phytotoxicity of Bispyribac sodium, Metsulfuron methyl and Chlorimuron ethyl on rice crop

BS: Bispyribac sodium; MSM: Metsulfuron methyl;

: Chlorimuron ethyl

Phytotoxicity Results: Slight stunting was observed with metsulfuron methyl and chlorimuron ethyl and their mixture, whereas no phytotoxicity was seen with the tank-mix combination of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl.

Claims

Claims:

1 . A synergistic herbicidal combination comprising of bispyribac sodium, metsulfuron methyl and chlorimuron ethyl.

2. A synergistic herbicidal composition comprising of bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl and agriculturally acceptable additives.

3. The synergistic herbicidal composition as claimed in claim 2, wherein said composition comprises of weight percentage of bispyribac sodium is 0.5% to 70% preferably from 1 0% to 50%, weight percentage of metsulfuron methyl is 0.5% to 20% preferably from 0.5% to 5%, weight percentage of chlorimuron ethyl is 0.5% to 20% preferably from 0.5% to 5%, and weight percentage of additives is 1 % to 90% preferably from 40% to 90%.

4. The synergistic herbicidal composition as claimed in claim 2, wherein agriculturally acceptable additives are selected from surfactant(s), solid carrier(s), liquid carrier(s), gaseous carrier(s), binder(s), disintegrating agent(s), pH adjuster(s), thickener(s), preservative(s), anti-freezing agent(s), defoamer(s), or coloring agent(s).

5. A method of post-emergence application of the synergistic herbicidal combination or the composition as claimed in claims 1 or 2, for the management of the weed flora in rice crop.

6. The synergistic herbicidal combination or composition as claimed in claims 1 or 2, wherein said combination or composition is used for the management of the weed flora in rice crop plants selected from Echinochloa species ( Echinochloa colonum, Echinochloa crus-galli), Physalis species ( Physalis minima), Phyllanthus species ( Phyllanthus niruri), Leptochola species ( Leptochola chinensis), Ludwigia species ( Ludwigia parviflora), Commelina species ( Commelina benghalensis), Cyperus species ( Cyperus iria, Cyperus difformis), Fimbristylis species ( Fimbristylis miliacea), or Eclipta species ( Eclipta alba).

7. The synergistic herbicidal combination or composition as claimed in claims 1 or 2, wherein said combination or composition additionally comprisies one or more compound selected from safener(s), herbicide(s), insecticide(s), fungicide(s), acaricide(s), nematicide(s) or any combination thereof.

8. The synergistic herbicidal composition as claimed in claim 2, wherein said synergistic herbicidal composition is selected from a wettable powder (WP), a water dispersible granule (WG), or an oil dispersion (OD) composition.

9. A method for preparation of said wettable powder composition as claimed in claim 8 comprising the steps of:

(a) addition of bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl,

(b) addition of agrochemically acceptable additives selected from surfactant(s), carrier(s) and other additive(s) uniformly in a mixer; and

(c) optionally milling by a mill.

10. A method for preparation of said water dispersible granule composition as claimed in claim 8 comprising the steps of:

(a) addition of carrier, bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl,

(b) addition of agrochemically acceptable additives selected from surfactant(s), binder(s), disintegrating agent(s) and other additive(s) uniformly in a mixer;

(c) optionally, milling by a mill; and

(d) water added to the mixture, granulated and dry the mixture.

1 1 . The synergistic herbicidal composition as claimed in claims 9 or 10, wherein said milling is carried out by an air jet mill to a median diameter of 2 to 10 pm.

12. A method for preparation of said oil dispersion composition as claimed in claim 8 comprising the steps of:

(a) addition of bispyribac sodium, metsulfuron methyl, and chlorimuron ethyl into a mixture of solvents and surfactant(s),

(b) addition of optional additive(s),

(c) optionally, milling of the above obtains mixture.

13. The synergistic herbicidal composition as claimed in claim 12, wherein said milling is wet milling and preliminary milling by a homogenizer and then milling by a bead mill to achieve median diameter to 1 to 5 pm.