Innovative synergistic herbicidal combination for weed suppression

Abstract

The present invention relates to a synergistic herbicidal composition comprising pyroxasulfone and pyrazosulfuron-ethyl or an agriculturally acceptable ester thereof. The combination exhibits a synergistic herbicidal effect, as determined by Colby's method, providing effective control of grasses, sedges, and broad-leaf weeds at reduced application rates compared to the individual active ingredients. In a preferred embodiment, the composition is formulated as a water-dispersible granule (WDG) comprising the active ingredients along with agriculturally acceptable formulation auxiliaries. The WDG formulation exhibits good dispersibility, wettability, and storage stability, forming a stable aqueous dispersion upon dilution. The formulation is characterized by an optimized particle size distribution, particularly a median particle size (Dv50) of ≤ 10 µm after dispersion, which enhances dispersion stability and biological efficacy. The composition is suitable for pre-emergence and early post-emergence application and is compatible with conventional agricultural spraying equipment.

Description

[0001] INNOVATIVE SYNERGISTIC HERBICIDAL COMBINATION FOR WEED SUPPRESSION FIELD OF THE INVENTION

[0002] The present invention relates to a synergistic herbicidal composition comprising pyroxasulfone and pyrazosulfuron, particularly in water-dispersible granule formulations, for controlling grasses, sedges, and broad-leaf weeds.

[0003] BACKGROUND OF THE INVENTION

[0004] Crop protection is a fundamental agricultural practice aimed at safeguarding crop yields from weeds, pests, plant diseases, and other harmful organisms that can significantly impact productivity. Effective weed management is particularly critical during the early growth stages of crops, as weed competition for nutrients, water, and sunlight can severely compromise both crop quality and yield. Unchecked weed growth can lead to reduced crop efficiency, increased production costs, and diminished market value, necessitating the use of herbicides as a primary means of weed control.

[0005] The application of herbicidal compositions is a well-established approach to suppress weed growth, with single-agent herbicides being widely utilized. However, reliance on a single active ingredient often leads to herbicide resistance in target weed populations due to continuous selection pressure. Furthermore, certain highly aggressive weed species exhibit inherent resistance or adaptability, rendering conventional herbicides ineffective over time. This resistance development presents a major challenge in sustainable weed management, necessitating the exploration of new herbicidal strategies that minimize environmental impact while ensuring long-lasting efficacy.

[0006] A synergistic herbicidal composition, comprising a combination of active ingredients with distinct mechanisms of action, offers a promising solution to overcome resistance issues and enhance weed control efficiency. By utilizing two or more complementary active ingredients in specific ratios, such compositions can achieve enhanced efficacy at lower application rates, reducing chemical load on the environment while maintaining effective, broadspectrum weed control. Additionally, herbicidal synergy can lead to faster action, prolongedresidual activity, and improved control over difficult-to-manage weed species, thereby ensuring sustainable agricultural productivity.

[0007] A key challenge in the field of crop protection is to develop herbicidal formulations that deliver high efficacy at reduced dosages, thereby minimizing toxicological and environmental concerns. Excessive or repeated application of solo herbicides accelerates weed resistance, which can significantly limit future weed management options.

[0008] Although combinations of herbicides are known, the prior art neither teaches nor suggests a synergistic combination of pyroxasulfone and pyrazosulfuron exhibiting enhanced efficacy at reduced dose, nor does it disclose a stable water-dispersible granule formulation having optimized particle size and dispersibility suitable for tropical storage conditions

[0009] Thus, there remains an unmet need for a novel synergistic herbicidal composition that effectively addresses these challenges. Such a composition should offer enhanced weed control, low environmental burden, and improved formulation characteristics, making it an ideal solution for modern agricultural practices.

[0010] OBJECT OF THE INVENTION

[0011] The primary object of the present invention is to provide a synergistic herbicidal composition comprising pyroxasulfone and pyrazosulfuron or an agriculturally acceptable ester thereof for effective control of weeds.

[0012] Another object of the present invention is to provide a herbicidal composition exhibiting enhanced herbicidal efficacy at reduced application rates compared to the individual active ingredients.

[0013] Another object of the present invention is to provide a herbicidal composition capable of controlling a broad spectrum of weeds, including grasses, sedges, and broad-leaf weeds. Another object of the present invention is to provide a stable water-dispersible granule (WDG) formulation of the herbicidal composition having good dispersibility, wettability, and storage stability under ambient and accelerated conditions.Another object of the present invention is to provide a herbicidal formulation having an optimized particle size distribution, particularly a median particle size (Dv50) of < 10 pm after dispersion, resulting in improved dispersion stability and biological efficacy.

[0014] Another object of the present invention is to provide a herbicidal composition that reduces the risk of development of herbicide-resistant weed populations by employing active ingredients having different modes of action.

[0015] Another object of the present invention is to provide a herbicidal composition that is safe to crops, easy to handle, and compatible with conventional agricultural application equipment.

[0016] SUMMARY OF THE INVENTION

[0017] The present invention relates to a synergistic herbicidal composition comprising pyroxasulfone and pyrazosulfuron or an agriculturally acceptable ester thereof, which provides enhanced weed control compared to the individual active ingredients or their simple admixtures.

[0018] In accordance with the invention, the combination of pyroxasulfone and pyrazosulfuron exhibits a synergistic herbicidal effect, resulting in effective control of grasses, sedges, and broad-leaf weeds at reduced application rates.

[0019] In a preferred embodiment, the herbicidal composition is formulated as a water-dispersible granule (WDG) comprising pyroxasulfone and pyrazosulfuron-ethyl along with one or more agriculturally acceptable formulation auxiliaries selected from wetting agents, dispersing agents, solid carriers, chelating agents, and antifoaming agents.

[0020] The WDG formulation of the present invention exhibits excellent dispersibility, wettability, and physical stability, forming a stable aqueous dispersion upon dilution. The formulation is characterized by an optimized particle size distribution, particularly a median particle size (Dv50) of < 10 pm after dispersion, which enhances dispersion stability and biological efficacy of the active ingredients.The formulation retains active ingredient content within acceptable limits after storage under accelerated conditions, thereby demonstrating improved storage stability suitable for tropical climates.

[0021] The synergistic herbicidal composition of the present invention is suitable for pre-emergence and early post-emergence application and is compatible with conventional agricultural spraying equipment. The composition provides broad-spectrum weed control, improved crop safety, and reduced risk of development of herbicide-resistant weed populations due to the complementary modes of action of the active ingredients.

[0022] DETAILED DESCRIPTION OF THE INVENTION

[0023] The present disclosure / specification refers to a synergistic herbicidal composition and the process for the preparation for crop protection.

[0024] The term “combination” can be replaced with the words “mixture” or “formulation” “composition” defined or refers to as combining two or more active ingredients formulated in desired formulations.

[0025] The term “pesticide” as used in this specification refers to a substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest or weeds which causes damage to the crop. Herbicides, insecticides, and fungicides are mainly used as pesticides which control weeds, insect pests and disease-causing pathogens respectively that eventually lead to a high yield of crops.

[0026] The term “Herbicides” as used in this specification refers to a substance or mixture of substances used to kill, control or eliminate unwanted plants or vegetation, commonly known as weeds that cause economic damage to crop and ornamental plants.

[0027] The term “crop protection” as used in this specification refers to method, practice or technology that safeguard cultivated plants from damage causing agents including pests, weeds, plant diseases, and other organisms.The term “synergism” as used in this specification refers to the interaction between two or more active compounds or other factors to produce a combined effect or properties that is greater than the sum of their separate effects or properties. The present invention involves the mixture of two active ingredients which has increased efficacy and broad spectrum of weed control when compared to individual use and admixture of those components.

[0028] Conventional herbicides have typical spectrums and effects, are limited to certain weeds only and their controlling activities are sometimes poor and not satisfactorily maintained for prolonged period, and those satisfactory herbicidal effects cannot be practically achieved. Even though some herbicides may bear satisfactory herbicidal effects, they require improvements in respect of environment & health safety and are also demanded to achieve a high herbicidal effect at a smaller dosage and lack of resistance management.

[0029] We found that this objective in part or total can be achieved by the combination of active compounds defined at the outset. The present inventors have intensively studied to solve these problems and found that by combining herbicide composition having pyroxasulfone and pyrazosulfuron in different formulation and percentages have astonishing effects of controlling weeds and also by reducing the amount of dosage than in the case of using an active compound alone and admixture of those compounds.

[0030] Pyroxasulfone is a pre and early post-emergent, systemic and selective isoxazoline herbicide used to control a wide range of annual grasses and broadleaf weeds. Its mode of action involves inhibiting the very-long-chain fatty acid synthesis (VLCFA), by inhibiting very-long-chain fatty acid (VLCFA) biosynthesis through inhibition of fatty acid elongase enzymes which is essential in weeds. This enzyme is crucial for the synthesis of carotenoids, which are essential pigments for chlorophyll formation in weeds. By inhibiting very-long-chain fatty acid (VLCFA) biosynthesis through inhibition of fatty acid elongase enzymes. Pyroxasulfone was effective against annual grasses, sedges and annual broadleaf weeds. Pyroxasulfone shows good selectivity for corn, soybeans, wheat, turf, cotton, potato and onion, and we intend to extend its use to other crops in future. It has both foliar and soil activity and this way it kills both newly emerged weeds and emerging new weeds from seeds.The second active ingredient is pyrazosulfuron, a broad-spectrum, selective systemic herbicide belonging to the sulfonylurea class, designed for effective weed management in rice cultivation. This herbicide is characterized by its systemic action, wherein it is absorbed through the roots and / or leaves and subsequently translocated to the meristematic regions and throughout the plant via the vascular system. Pyrazosulfuron-ethyl functions as an acetohydroxyacid synthase (AHAS) inhibitor, also known as an acetolactate synthase (ALS) inhibitor, disrupting the biosynthesis of branched-chain essential amino acids, specifically valine and isoleucine. This disruption halts cell division and plant growth, leading to the eventual demise of target weed species.

[0031] The herbicide demonstrates high selectivity in rice crops due to the rapid metabolic degradation of its active ingredient in the plant. This selectivity primarily results from the demethylation of the methoxy group, enabling rice plants to break down the compound efficiently while maintaining its herbicidal efficacy against broadleaf weeds, grasses, and sedges.

[0032] The present invention provides a synergistic herbicidal composition having two main effective components of pyroxasulfone and pyrazosulfuron and purpose thereof. This inhibiting very-long-chain fatty acid (VLCFA) biosynthesis through inhibition of fatty acid elongase enzymes and also inhibits acetolactate synthase (ALS), disrupting the biosynthesis of branched-chain essential amino acids, specifically valine and isoleucine of weeds to achieve herbicidal effects can generate efficient synergism in pre-emergence, early-post or post- emergence stages of crops and can enable broad spectrum satisfactory weed control and protect the several crop from sedges, grasses and broad leaf weeds for prolonged period of time at lower dose with no phytotoxic effect. Their different modes of action target two different sites resulting in effectiveness, crop safety and environmental friendliness as they are applied at doses lower than they were applied alone on the crop and increasing the probability of this herbicidal mixture as a valuable tool in weed control. It also prevents the weed crop from rejuvenation and further regeneration.

[0033] In one embodiment of the present invention provides a synergistic herbicidal composition comprising:a) pyroxasulfone; and

[0034] b) pyrazosulfuron or an agriculturally acceptable ester thereof.

[0035] In one aspect of the present embodiment, unless otherwise indicated, pyroxasulfone is 3 -[[5-(difluoromethoxy)-l-methyl-3-(trifluoromethyl)pyrazol-4-yl]methyl sulfonyl] -5,5-dimethyl-4Z7-l,2-oxazole and possess the following structure:

[0036]

[0037] In a further aspect of the present embodiment, pyrazosulfuron is 5-[(4,6-dimethoxypyrimidin-2-yl) carbamoylsulfamoyl]-l-methylpyrazole-4-carboxylate

[0038] In another aspect of the present embodiment, pyrazosulfuron also refers to an ethyl 5-[(4,6-dimethoxypyrimidin-2-yl) carbamoylsulfamoyl]- 1 -methylpyrazole-4-carboxylate and possesses the following structure:

[0039]

[0040] In yet another aspect of the first embodiment, an agriculturally acceptable esters of pyrazosulfuron encompasses all the agriculturally acceptable esters of pyrazosulfuron known in the art or provided herein. In one embodiment, the agriculturally acceptable ester of pyrazosulfuron is an ethyl (e.g., pyrazosulfuron -ethyl)

[0041] In another embodiment of the present invention provides a synergistic herbicidal composition comprising:

[0042] a) pyroxasulfone; and

[0043] b) pyrazosulfuron or an agriculturally acceptable ester thereof;In one aspect of the present embodiment, the pyrazosulfuron is an ester form of Pyrazosulfuron-ethyl .

[0044] In yet another embodiment of the present invention provides a synergistic herbicidal composition comprising:

[0045] a) pyroxasulfone; and

[0046] b) pyrazosulfuron-ethyl;

[0047] wherein, the weight ratio of pyroxasulfone to pyrazosulfuron-ethyl is from (1-100) : (1-80).

[0048] In a further embodiment of the present invention provides a synergistic herbicidal composition comprising:

[0049] a) pyroxasulfone;

[0050] b) pyrazosulfuron-ethyl; and

[0051] c) at least one agriculturally acceptable excipient.

[0052] In one aspect of the present embodiment, agriculturally acceptable excipient selected from but not limited to the group comprising liquid medium, surfactant, stabilizer, anti-freezing agent, anti-foaming agent, anticaking agent, dispersing agent, adjuvant and other auxiliaries. These are selected according to the respective types of formulation requirements, and which will facilitate in the preparation of different formulations.

[0053] In another aspect of the present embodiment, liquid medium acts as a carrier for the active ingredients and provides a stable environment for suspension selected form but not limited to water and organic solvents.

[0054] Further aspect of the present embodiment, surfactant includes wetting agent and emulsifier. Further aspect of the present embodiment, emulsifiers include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, amphoteric emulsifiers, phospholipids and glyceryl esters.

[0055] Further aspect of the current embodiment, anionic emulsifiers selected from but not limited to sodium lauryl sulfate (SLS), sodium dodecyl benzenesulfonate (SDBS), alkyl sulfates and calcium alkyl benzene sulfonate.Further aspect of the current embodiment, cationic emulsifiers selected from but not limited to cetyl trimethyl ammonium bromide (CTAB) and stearalkonium chloride.

[0056] Further aspect of the current embodiment, nonionic emulsifiers selected from but not limited to Polysorbate 80, Polysorbate 20, Sorbitan monolaurate, ethoxylates, Sorbitan monooleate and Polyaryl sulfate esters.

[0057] Further aspect of the current embodiment, amphoteric emulsifiers selected from but not limited to cocamidopropyl betaine, lauramidopropyl betaine; ethoxylated emulsifiers: ethoxylated nonylphenol (nonylphenol ethoxylate), ethoxylated sorbitan esters and ethoxylated fatty alcohols.

[0058] Further aspect of the current embodiment, wetting agent is selected from but not limited to block copolymers and Alkyl Naphthalene Sulfonates.

[0059] Further aspect of the current embodiment, the block copolymers selected from the but not limited to styrene-butadiene block copolymer (SBS), polyethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO or pluronic), polystyrene-poly(ethylene oxide) (PS-PEO), poly(butadiene)-poly(styrene) (PB-PS), poly(methyl methacrylate)-poly(butadiene)-poly(methyl methacrylate) (PMMA-PB-PMMA), poly(caprolactone)-poly(ethylene glycol) (PCL-PEG), Polyethylene glycol nonyl phenyl ether ammonium sulfate, poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (PEG-PPG-PEG or pluronics). more preferably Dialkyl naphthalene sulphonate sodium salt.

[0060] Further aspect of the current embodiment, stabilizer includes antioxidant, chelating agent, pH adjusters, UV absorber, stabilizing polymers and inert, wherein the chelating agents selected from but not limited to ethylene diamine tetraacetic acid disodium zinc salt (zinc EDTA).

[0061] Further aspect of the current embodiment, anti-foaming agents selected from but not limited to silicone-based anti-foams, polyethylene glycol-based anti-foams, mineral oil-based antifoams, ethylene glycol-based anti-foams, polysorbate-based anti-foams, dimethicone-basedanti-foams, polypropylene glycol-based anti-foams, vegetable oil-based anti-foams, alkyl siloxane-based anti-foams and fatty acid-based anti-foams; preferably alkyl siloxane based anti-foams; more preferably siloxane polyalkyleneoxide (Polydimethylsiloxane).

[0062] Further aspect of the present embodiment, dispersing agents selected from but not limited to polyethylene glycol, polysorbate, poly acrylate, poly(methyl methacrylate), polyvinyl alcohol, poly ethoxylated alcohol, poly ethoxylated fatty acids, polyacrylic acid, polyvinylpyrrolidone, alkyl sulfonates, aryl sulfonates, sodium tripolyphosphate, sodium dodecyl sulfate, sodium lignosulfonate, sodium carboxymethyl cellulose, hydroxypropyl methylcellulose, sorbitan esters (e.g., sorbitan monolaurate, sorbitan monooleate), gum arabic and carbomer and / or their comb polymers; preferably poly(m ethyl methacrylate) and polyethylene glycol comb polymer. More preferably, naphthalene sulphonic acid and phenol sulphonic acid salts or sodium-neutralized, modified styrene acrylic acid copolymers.

[0063] The dispersing agent maintains particle separation after dispersion, thereby preventing sedimentation.

[0064] Further aspect of the current embodiment, adjuvant includes but not limited to spreader, modifier, sticker, penetrant, drift control agent, buffering agent, thickener, compatibility agent, binders and safener.

[0065] Further aspect of the current embodiment, thickener / carrier selected from but not limited to polysaccharides / carboxymethyl cellulose / bentonite clay, China clay, hydroxy propyl cellulose montmorillonite, bentonite, magnesium aluminium silicate and attapulgite; preferably water-soluble polysaccharides.

[0066] Further aspect of the current embodiment, modifiers include drift control modifiers, rainfastness modifiers, anti-foaming modifiers, UV stabilizers, pH modifiers, compatibility modifiers and rheology modifiers.

[0067] Further aspect of the present embodiment, antibacterial agent selected from but not limited to triclosan, triclocarban, clotrimazole, miconazole, copper-based compounds, chlorothalonil, benzisothiazolin-3-one (BIT), 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one (MIT), octylisothiazolinone (OIT), dodecylbenzenesulfonic acid and sodium salt (DBSA); preferably benzisothiazolin-3-one (BIT).

[0068] This combination can be developed in the form of Emulsifiable Concentrates (EC), Dispersible Concentrates (DC), Oil Dispersions (OD), Suspension Concentrates (SC), Soluble Liquids (SL), Suspo-emulsion (SE), Emulsion Concentrates (EW), Microemulsions, Wettable Powders (WP), Water-Dispersible Granules (WG), Soluble Powders (SP), Granules (G), Oil Solutions (OS), Aqueous Suspensions (AS), Aqueous Solutions (AS), Microencapsulated Suspensions (ME), and Microencapsulated Emulsions (MEC), mixed formulation of Suspension Concentrate and Capsule Suspension (ZC) and other conventional formulations.

[0069] In a preferred embodiment of the present invention, the synergistic herbicidal composition is provided in the form of a water-dispersible granule (WDG) comprising pyroxasulfone and pyrazosulfuron-ethyl in a synergistically effective ratio, together with agriculturally acceptable formulation auxiliaries.

[0070] In this embodiment, pyroxasulfone is present in an amount ranging from 30 to 50% w / w, and pyrazosulfuron-ethyl is present in an amount ranging from 5 to 15% w / w, based on the total weight of the formulation. The ratio of pyroxasulfone to pyrazosulfuron-ethyl within the said ranges is selected to provide a synergistic herbicidal effect.

[0071] According to this embodiment, the composition preferably comprises pyroxasulfone technical (98% purity) in an amount of about 44.39% w / w, corresponding to 42.50% w / w of active pyroxasulfone, and pyrazosulfuron-ethyl technical (97.80% purity) in an amount of about 8.28% w / w, corresponding to 7.50% w / w of active pyrazosulfuron-ethyl. The weight ratio of pyroxasulfone to pyrazosulfuron-ethyl in the composition is thus maintained at a level effective to produce a synergistic herbicidal effect against a broad spectrum of weeds.

[0072] The composition further comprises one or more agriculturally acceptable excipients, including dialkyl naphthalene sulphonate sodium salt as a wetting agent in an amount of about 2.00% w / w, and a mixture of salts of naphthalene sulphonic acid and phenol sulphonicacid condensation products or Modified styrene acrylic polymers as dispersants in an amount of about 6.00% w / w. China clay, in an amount of about 35.83% w / w, is employed as a solid carrier to impart suitable bulk density and granule integrity. A chelating agent, ethylene diamine tetra acetic acid disodium zinc salt (zinc EDTA), is included in an amount of about 3.00% w / w to enhance formulation stability. A silicone-based anti-foam emulsion is incorporated in an amount of about 0.50% w / w to control foam formation during dispersion.

[0073] The resulting WDG formulation exhibits excellent dispersibility, wettability, suspensibility, and storage stability, and demonstrates enhanced herbicidal efficacy due to the synergistic interaction between pyroxasulfone and pyrazosulfuron-ethyl. This preferred embodiment is particularly suitable for pre-emergence and early post-emergence weed control in crops including rice, wheat, maize, and other field crops, while exhibiting minimal phytotoxicity and improved environmental safety.

[0074] Another embodiment of the present invention, the synergistic herbicidal composition of present invention used in different dose ratios shows effective weed control in broad spectrum of weeds and increases the crop yield, quality, and lesser dose rations and shows no phytotoxicity compared to single components, admixture of those two components and other available market standards. By this the herbicidal composition of present invention archives synergistic effect along with economic value products and improved environmental safety by reducing toxicity and residue deposit in soil and in crops.

[0075] Another embodiment of the present invention, a method of controlling annual grasses, sedges and broad leaf weeds comprising synergistic herbicidal composition applying to the location of weed in effective amount.

[0076] Another embodiment of the present invention, the herbicidal composition obtained from the present invention is used to control but not limited to broadleaf weeds, sedges and annual grasses in rice, wheat, fruits, roots, tubers, vegetables, maize, grains, sugarcane, cereals, field crops and various other crops for general weed control.

[0077] Another embodiment of the present invention, the synergistic herbicidal composition can be applied to pre-emergence, early post-emergence or post-emergence stages for weed controlby conventional spraying methods, such as foliar application etc., over the target areas of weeds or vegetation at same time avoiding excessive drift or runoff of the composition securing thorough coverage.

[0078] The combined use of pyroxasulfone and pyrazosulfuron as an herbicidal mixture offers a synergistic weed control strategy, enhancing efficacy and reducing the risk of resistance. The dual action of these herbicides provides a more comprehensive approach to weed management, targeting different biochemical pathways in weeds and ensuring improved crop performance mainly in wheat. This combination not only broadens the spectrum of weed control but also maintains a more sustainable agricultural practice by reducing the chances of weed adaptation. By integrating herbicidal mixtures into wheat farming, Indian agriculture can achieve better productivity, addressing both weed-related challenges and the need for higher yields despite fluctuating climatic conditions.

[0079] The best mode presently contemplated by the inventors for carrying out the invention relates to the preparation of a storage-stable water-dispersible granule (WDG) composition comprising pyroxasulfone and pyrazosulfuron-ethyl, wherein the process ensures fine particle size distribution, uniform granule formation, and compliance with FAO / CIPAC specifications.

[0080] According to the best mode, pyroxasulfone technical (42.50% w / w) and pyrazosulfuron-ethyl technical (7.50% w / w) are first blended with agriculturally acceptable solid carriers, dispersants, wetting agents, and chelating agents, excluding the binder, to form a homogeneous premix. The premix is subjected to air jet milling in two successive passes, wherein the grinding air pressure is maintained in the range of 2 to 3 bar and the operating pressure is maintained in the range of 4 to 6 bar, so as to obtain a finely milled premix having a particle size distribution of DvlO of about 1.15 pm, Dv50 of about 3.48 pm, and Dv90 of about 9.90 pm.

[0081] The milled premix is then converted into a plastic dough by the gradual addition of an aqueous binder solution comprising about 0.50% w / w of a granulation binder dissolved in distilled water, wherein the total amount of water added ranges from about 18 to 20% w / wbased on the total composition. The resulting dough is extruded using an extruder to obtain wet granules of uniform size.

[0082] The wet granules are dried in a fluidized bed dryer at a temperature of about 50°C for a period of 30 to 45 minutes, followed by sieving through 8 BSS and 25 BSS sieves to obtain granules within the desired particle size range. The resulting WDG composition exhibits excellent dispersibility, suspensibility, and storage stability and conforms to applicable FAO specifications and CIPAC analytical methods.

[0083] This mode of operation has been found to provide optimal granule integrity, reduced dust formation, and consistent biological efficacy, and therefore represents the best mode of performing the invention as of the filing date.

[0084] EXAMPLES:

[0085] Example 1: Water Dispersible Granule formulation of Pyroxasulfone 42.50 + Pyrazosulfuron ethyl 7.50 % w / w

[0086]

[0087] *According to purity of both technical, charging quantity of technical will be change.

[0088] Example 2: Water Dispersible Granule formulation of Pyroxasulfone 42.50 + Pyrazosulfuron ethyl 7.50 % w / w

[0089]

[0090] *According to purity of both technical, charging quantity of technical will be change.

[0091] Process for Preparing a Water-Dispersible Granule (WDG) Composition Comprising Pyroxasulfone and Pyrazosulfuron-ethyl

[0092] This commercial batch should be carried out at 25±5°C temperature. During Lab trials we did not find exothermic / endothermic change after sequential addition as below mentioned. Sequence wise operations enlisted and have followed same process below for producing / making WDG formulation:

[0093] This example illustrates a non-limiting process for preparing a water-dispersible granule (WDG) composition comprising pyroxasulfone (42.50% w / w) and pyrazosulfuron-ethyl (7.50% w / w) along with agriculturally acceptable auxiliaries.

[0094] Step A: Preparation of Premix: All solid formulation auxiliaries except binder were accurately weighed according to the composition. The weighed materials, comprising china clay, zinc EDTA, dispersant(s), wetting agent(s), and other formulation additives, were initially blended together. Thereafter, pyrazosulfuron-ethyl technical and pyroxasulfone technical were added to the blend. The resulting mixture was manually premixed for a period of approximately 3 to 5 minutes to obtain a substantially homogeneous premix.

[0095] Step B: Air Jet Milling: The premix obtained in Step A was subjected to air jet milling to achieve the desired particle size distribution. Milling was carried out under compressed air, wherein the grinding air pressure was maintained in the range of 2 to 3 bar, and the operatingpressure during milling was maintained in the range of 4 to 6 bar. The premix was passed through the air jet mill for two successive passes.

[0096] The particle size distribution of the premix prior to milling was: DvlO: about 2.81 pm; Dv50: about 123 pm; Dv90: about 492 pm

[0097] After air jet milling, the particle size distribution was reduced to: DvlO: about 1.15 pm; Dv50: about 3.48 pm; Dv90: about 9.90 pm

[0098] Step C: Dough Preparation: A granulation dough was prepared by mixing the milled premix with an aqueous binder solution. The binder solution comprised SAG- 1572 in an amount of about 0.50% w / w, dissolved in distilled water. The amount of water used for dough formation ranged from about 18 to 20% w / w, based on the total formulation weight. Mixing was continued until a uniform, plastic dough suitable for extrusion was obtained.

[0099] Step D: Extrusion: The dough prepared in Step C was subjected to extrusion using a laboratory-scale extruder to obtain wet granules of uniform shape and size.

[0100] Step E: Drying: The wet granules obtained from Step D were dried in a fluidized bed dryer. Drying was carried out at a temperature of approximately 50°C for a duration of about 30 to 45 minutes, or until the desired residual moisture content was achieved.

[0101] Step F: Sieving: The dried granules were sieved sequentially through 8 BSS and 25 BSS sieves to remove oversized and undersized particles. Granules retained within the desired size fraction were collected as the final WDG product.

[0102] Step G: Analysis: Representative samples of the obtained WDG composition were analysed in accordance with FAO specifications and relevant CIPAC methods to confirm active ingredient content, dispersibility, wetting time, suspensibility, moisture content, and other quality parameters.

[0103] Step H: Packaging: Upon meeting all analytical and quality requirements, the WDG formulation was packed in suitable containers for storage, transportation, and commercial use.

[0104] Example 3: Stability EvaluationThis example demonstrates the storage stability of the water-dispersible granule (WDG) composition comprising pyroxasulfone and pyrazosulfuron-ethyl prepared according to the process described herein.

[0105] Representative samples of the WDG formulation were subjected to ambient storage conditions and accelerated heat storage (AHS) at 54 ± 2°C for 14 days, and were evaluated for physical and chemical stability parameters in accordance with applicable FAO specifications and CIPAC test methods.

[0106]

[0107] Example 4: Bio efficacy and phytotoxicity studies of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG

[0108] Methodology:

[0109] The molecules under focus in this study were evaluated as their pre-emergence against various weed flora, the different actives involved are i.e., Pyroxasulfone, Pyrazosulfuron Ethyl. The said combination of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG had been evaluated against weed flora of paddy and wheat crop. The herbicidal combination has been tested as two-way combination, the same solo molecules as individual were takeninto note and the efficacy of all the molecules are evaluated and compared. The treatment details are mentioned in Table 1. To justify the results the overall effect and other parameters are calculated over untreated check. To detect any existing synergistic activity in the combinations Colby’s ratio is calculated from the results and to see their effect on weed management. The residual effect of the herbicidal combination has been evaluated on the succeeding crop as well to assess the effect on germination and yield. The experimental area was first divided into plots for each treatment and replicated three times following Randomized Block Design. The spraying method followed was foliar application with the help of a knapsack sprayer fitted with flat fan nozzle. The combinations are even tested against any signs of Phytotoxicity on paddy.

[0110]

[0111] Table la. Treatment details for paddy

[0112]

[0113] Table lb. Treatment details for wheat

[0114]

[0115] Method of observations:

[0116] 1. No. of weed / I sq meter: Take 4 sticks / pipes of 1 meter each and tie their ends / joints so that they make a square shape which looks like a quadrant. Before taking the weed counts, the square (quadrant) should be placed in the treated plot randomly and the number of weed species in the 1 metre area were counted.

[0117] 2. Based on the observations recorded, conclusions were drawn based on the parameters like Percent weed control (in case of weed population) and Weed control index (WCI) which indicates the accumulations of biomass in the weed flora before and after the treatments.

[0118] 3. For checking the presence of synergism, Colby’s ratio was calculated.

[0119] 4. Take the observation on the crop safety of herbicide i.e., Phytotoxicity / softener observation of herbicide after application at 5 and 10 Days after application.

[0120] 5. For testing the residual effect on crops, the percent germination and at time of harvest the Plant height, Number of Branches, Number of Nodules and yield were recorded.

[0121] Parameters of observations:

[0122] The weeds controlled in each treatment are calculated as percentage weed controlled over untreated check plot. The percent weed control is calculated by the following formula - , No.of weeds in control plot-No.of weeds in treated plot ,

[0123] % weed control = - - - - - - - - — x 100 No.of weeds in control plotThe weeds biomass built up in treatments is calculated to know the weed control index of each treatment. The Weed Control Index (WCI) is calculated by the following formula - ,T, Dry wt.of weeds in control plot-Dry wt. of weeds in treated plot , Weed Control Index = — - - - - - - - - - - — x 100 Drywt. of weeds in control plot

[0124] Colby’s Method: The combined effect of Pesticidal combinations is the sum of their individual effects. Colby’s method is an approach to evaluate the synergistic, additive, or antagonistic effects due to the interactions of two or more pesticides as a combination.

[0125] • Colby’s method calculates expected response, and a ratio is calculated between expected response and observed response.

[0126] • The formula for expected response is as follows- Two-way combination - E = (A+B) - ((A*B) / 100)

[0127] • A represents pesticide 1, B represents pesticide 2

[0128] • The observed response is the actual percent control achieved

[0129] • Colby’s ratio = Observed response (O) / Expected response (E).

[0130] • If the ratio is,

[0131] < 1 = Antagonistic effect

[0132] 1 = Additive effect

[0133] > 1 = Synergistic effect

[0134] Results:

[0135] The herbicide combination, Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG applied at a doses of 375, 250 and 175 gm / ha were effective against the weed flora viz., grasses, broad leaved weeds and sedges, so the crops in the field experiments are enlisted below,

[0136] • Paddy with a succeeding crop of green gram

[0137] • Wheat with a succeeding crop of black gram

[0138] The different types and species of weeds found in this experiment in paddy field were enlisted below,

[0139] Grasses

[0140] • Echinocloa crusgalli, Cyanodon dactylonBroad Leaved Weeds

[0141] • Ludwigia parviflora, Monochoria vaginalis, Eclipta alba

[0142] Sedges

[0143] • Cyprus iria, Fimbristylis miliaceae

[0144] The different types and species of weeds found in this experiment in wheat field were enlisted below,

[0145] Grassy weeds - Phalaris minor

[0146] Borad leaved weeds - Chenopodium album, Trianthema portulacastrum, Amaranthus viridis

[0147] Sedges - Cyperus rotundus, Cyperus iria

[0148] Example 4.1: Paddy

[0149] Table 2. Synergistic effect of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG against different weed flora of Paddy crop

[0150]

[0151] (E) - Expected % (O) - Observed %Table 3. Efficacy of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG against different weed flora of Paddy crop

[0152]

[0153] Table 4. Efficacy of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG on yield attributes and yield of Paddy crop

[0154]

[0155] Succeeding crop (Green gram)

[0156] The follow up crop for paddy is green gram in this study and the residual effect of the herbicidal applications on the succeeding crop proved that it shows no much effect on the succeeding crop as the germination percentage of the crop did not vary much within the treatments as it commonly ranged between 85.41% to 96.11% apart from untreated control (80.45%) and plant height at the time of harvest was observed in between 41 ,23 cm to 51.02cm apart from control (35.23 cm).

[0157] Table 5. Residual effect of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG on succeeding crop (Green gram)

[0158]

[0159] Table 6. Phytotoxicity of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG and other herbicides on Paddy

[0160] Example 4.2: Wheat

[0161]

[0162] Table 7. Synergistic effect of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG against different weed flora of Wheat crop

[0163]

[0164] (E) - Expected % (O) - Observed %Table 8. Efficacy of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG against different weed flora of Wheat crop

[0165]

[0166] Table 9. Efficacy of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG on yield attributes and yield of Wheat crop

[0167]

[0168] Succeeding crop (Black gram)

[0169] The follow up crop for wheat is black gram in this study and the residual effect of the herbicidal applications on the succeeding crop proved that it shows no much effect on the succeeding crop as the germination percentage of the crop did not vary much within the treatments as it recorded > 90% germination in all treatments apart from untreated control (81.33%). The plant height at the time of harvest was observed in between 32.62cm to 23cm apart from control (20cm) and the number of nodules at the time of harvest were ranging in between 14.38 to 18.67 among the treatments apart from control (12.99).

[0170] Table 10. Residual effect of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG on succeeding crop (Black gram)

[0171]

[0172] Table 11. Phytotoxicity of Pyroxasulfone 42.5% + Pyrazosulfuron ethyl 7.5% WDG and other herbicides on Wheat

[0173] The phytotoxicity effect of the herbicide Pyroxasulfone 42,5% + Pyrazosulfuron ethyl

[0174]

[0175] 7.5% WDG formulation at three doses and other herbicides showed no signs of phytotoxicity in the wheat crop. Hence, the combination is safe for the usage of effective weed management in wheat crop (Table 11).

[0176] The results confirm that the observed herbicidal efficacy exceeds the expected additive effect, thereby establishing synergism.

[0177] Advantages of Present Herbicidal Composition:

[0178] The present invention provides a synergistic herbicidal composition comprising pyroxasulfone and pyrazosulfuron-ethyl, particularly in the form of a water-dispersible granule (WDG), which offers the following advantages:• The composition exhibits a true synergistic herbicidal effect, as determined by Colby’s method, providing enhanced weed control compared to the individual active ingredients or their simple admixtures.

[0179] • The composition provides broad-spectrum control of grasses, sedges, and broadleaf weeds due to the complementary and independent modes of action of the active ingredients.

[0180] • The synergistic interaction enables effective weed control at reduced application rates, thereby lowering chemical load and improving crop safety.

[0181] • The dual mode of action reduces selection pressure on weeds and delays the development of herbicide resistance.

[0182] • The WDG formulation exhibits excellent physical and chemical stability, retaining active ingredient content within specification limits after accelerated storage at elevated temperature.

[0183] • The WDG formulation rapidly disperses in water to form a stable suspension with high suspensibility and good wettability, ensuring uniform distribution of the active ingredients during application.

[0184] • The controlled and optimized particle size distribution of the formulation, particularly a median particle size (Dv50) of < 10 pm after dispersion, enhances dispersion stability, minimizes sedimentation, and improves bioavailability and biological efficacy of the active ingredients.

[0185] • The WDG formulation produces minimal dust during handling and application, thereby improving operator safety and ease of use compared to conventional solid formulations.

[0186] • The reduced dose requirement and stable formulation contribute to a lower environmental impact and improved environmental safety.

[0187] • The formulation is compatible with conventional agricultural spraying equipment and is suitable for pre-emergence and early post-emergence applications.

[0188] • The composition and formulation are amenable to large-scale industrial manufacture using standard granulation techniques, ensuring commercial applicability.Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the disclosure(s), of appropriate materials and methods are described herein.

[0189] The numerical values given for various physical parameters, dimensions, and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions, and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.

[0190] While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

We Claim:

1. A synergistic herbicidal composition comprising:(a) pyroxasulfone;(b) pyrazosulfuron or an agriculturally acceptable ester thereof; and(c) one or more agriculturally acceptable excipients.wherein the composition exhibits a synergistic herbicidal effect against grasses, sedges, and broad-leaf weeds.

2. The composition as claimed in claim 1, wherein the pyrazosulfuron ester is pyrazosulfuron-ethyl .

3. The composition as claimed in claim 1, wherein the agriculturally acceptable excipients selected from but not limited to the group comprising surfactants, inert materials / carriers / thickeners, wetting agents, anti-foaming agents, Stabilizers / chelating agents, dispersing agents, binders and adjuvants.

4. The composition as claimed in claim 1 to 2, wherein the weight ratio of pyroxasulfone to pyrazosulfuron-ethyl thereof is from 1:1 to 100:1.

5. The composition as claimed in claim 1, comprising: a) pyroxasulfone is present in an amount ranging from 30-50% w / w, b) pyrazosulfuron-ethyl is present in an amount ranging from 5-15% w / w, and c) one or more agriculturally acceptable excipients present in an amount of 1-80% by weight.

6. The composition according to claim 1, wherein the composition is in the form of a water-dispersible granule (WDG).

7. The composition according to claim 6 or 7, wherein the formulation has a particle size (Dv50) of < 10 pm.

8. A water-dispersible granule (WDG) herbicidal formulation comprising:(a) pyroxasulfone in an amount of 30-50% w / w;(b) pyrazosulfuron-ethyl in an amount of 5-15% w / w; and(c) one or more agriculturally acceptable formulation excipients,wherein the formulation exhibits: a median particle size (Dv50) of < 10 pm after dispersion in water, andand wherein the formulation exhibits a synergistic herbicidal effect against grasses, sedges, and broad-leaf weeds.

9. A water-dispersible granule (WDG) herbicidal formulation comprising:(a) pyroxasulfone in an amount of 30-50% w / w;(b) pyrazosulfuron-ethyl in an amount of 5-15% w / w;(c) a wetting agent comprising dialkyl naphthalene sulphonate sodium salt in an amount of 1-4% w / w;(d) a dispersing agent comprising a condensation product of naphthalene sulphonic acid and phenol sulphonic acid salts or modified styrene acrylic polymers in an amount of 4-8% w / w;(e) a solid carrier comprising china clay in an amount of 30-40% w / w;(f) a Stabilizer / chelating agent comprising ethylene diamine tetra acetic acid disodium zinc salt (zinc EDTA) in an amount of 1-5% w / w; and(g) an anti-foaming agent comprising a silicone-based anti-foam in an amount of 0.1-1.0% w / w,wherein the formulation forms a stable water dispersion having a median particle size (Dv50) of < 10 pm,and wherein the formulation exhibits a synergistic herbicidal effect against grasses, sedges, and broad-leaf weeds.

10. A method for controlling weeds in a rice and wheat crops, comprising applying an effective amount of the synergistic herbicidal composition as claimed in any one of claims 1 to 9 to the soil or locus of weeds, wherein the composition is applied as a pre-emergence treatment.

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