FIELD OF THE INVENTION

[001] The present invention relates generally to herbicidal compositions or formulations, and to methods of using such compositions to kill or control the growth and proliferation of unwanted plants and weeds. More particularly, the present invention relates to herbicidal compositions comprising 2,4-D sodium salt, Glufosinate ammonium and Chlorimuron Ethyl with one or more suitable adjuvants.

BACKGROUND OF THE INVENTION

[002] Weeds present at planting will generally grow much quicker than crop plants and thus compete very early in the growing season thereby damaging the crop plants and reducing crop yield. Thus, it is desirable to plant the crop in a weed- free seed bed or to assure that essentially no weeds are present when the crop emerges. Bum-down may also entail weed control on fallow crop land. Burn-down, i.e., the complete removal of weeds from the soil by application of herbicides prior to planting or emergence of a crop, is an important tool of modem weed management.

[003] In industrial weed management and forestry, it is desirable to control a broad range of weeds for an extended period of time. The control of large weeds, or taller species such as bushes or trees may also be desirable. Industrial weed management includes for example railway and right-of-way management, fence lines and noncrop land such as industrial and building sites, gravel areas, roads or sidewalks. Forestry includes for example the clearing of existing forest or bush-land, the removal of regrowth after mechanical forest cutting, or the management of weeds under forestry plantations.

[004] Glufosinate and its salts are non-selective systemic herbicides having a good post-emergence activity against numerous grass weeds and thus can be used in burn-down programs. However, solo application of glufosinate often yields unsatisfactory weed control, and several applications and/or high dosage rates are often required. Moreover, the effectiveness of glufosinate against difficult-to- control broadleaf species and rhizomatous grasses is poor. Therefore, it is frequently recommended to apply glufosinate in combination with at least one second herbicide, such as triazines such as atrazine or metribuzin, chloroacetanilides such as metolachlor or dimethenamid (including dimethenamid- P), linuron and/or pendimethalin. However, the effectiveness of such combinations is often not satisfactory and high application rates are still required to achieve an acceptable control of a broad spectrum of weeds. Moreover, the reliability of such combinations depends strongly on the weathering conditions and certain difficult to control weed species may escape. In addition, the herbicidal activity of these compositions persists only for a short time, which allows effective burn-down only within a small timeframe prior to planting a crop. Moreover, the persistence of the herbicidal activity strongly depends upon the weathering conditions.

[005] It is therefore desired to provide an improved herbicidal composition of Glufosinate ammonium and convenient method which safely and effectively control weed species in the agricultural crops and therefore, there is a constant need for the development and application of synergistic formulations which are not only effective in weed control, but also help in increasing the yield of crop, having potential to manage the challenges of resistance development and shifting of weed flora.

SUMMARY OF THE INVENTION

[006] The present invention provides a herbicidal composition that enable efficient and reliable control of grass and broad-leaf weeds, having persistent herbicidal activity to achieve weed control over a sufficiently long period of time, thus allowing more flexible application. The compositions of the present invention have low toxicity to humans or other mammals and provides accelerated action on harmful plants.

[007] The present invention provides a herbicidal composition comprising a mixture of 2,4- Dichlorophenoxy acetic acid or its salts, Glufosinate ammonium, and Chlorimuron ethyl in effective amounts and adjuvants, wherein the 2,4- Dichlorophenoxy acetic acid or its sodium salts is present in a range from 40% (w/w) to 47% (w/w); Glufosinate ammonium is present in a range from 10% (w/w) to 15% (w/w); and Chlorimuron ethyl is present in a range from 0.15% (w/w) to 0.40% (w/w).

[008] In an embodiment of the present invention, the adjuvants are selected from a wetting agent, a dispersing agent, a rheology modifier, a buffer and a filler.

[009] In an embodiment of the present invention, the wetting agent is selected from the group comprising dialkyl naphthalene sulphonate sodium salt, alkylnaphthalene sulfonate condensate blend, sodium ligno sulphonate, linear alcohol derivative and polyethylene glycol nonyl phenyl ether ammonium sulfate, present in a range from 4% to 5% w/w.

[010] In an embodiment of the present invention, the dispersing agent is selected from the group comprising Sodium salt of poly alkyl naphthalene sulfonate, sodium ligno sulphonate, acrylate copolymer, phenol sulfonic acid-formaldehyde- polycondensation as sodium salt, sodium polycarboxylate, sodium methyl oleoyl taurate and sodium lauryl sulphate or combination thereof, present in a range from 4% to 5.5% w/w.

[Oil] In an embodiment of the present invention, the rheology modifier is silicon dioxide, present in a range from 1.5% to 2.5% w/w.

[012] In an embodiment of the present invention, the buffer is selected from the group comprising oxalic acid, citric acid, orthophosphoric acid and disodium hydrogen orthophosphate present in a range from 0.20% to 0.22% w/w.

[013] In an embodiment of the present invention, the filler is selected from the group comprising corn starch, lactose monohydrate, quartz, talc, kaolin, pyrophyllite, montmorillonite, attapulgite, bentonite clay, china clay, kieselguhr, chalk, zeolite, calcite, sericite, acid clay, diatomaceous earth, natural rock, Fuller’s earth, meerschaum, gibbsite, dolomite or pumice; synthetic minerals such as precipitated silica, fumed silica, sodium silicate, silicon dioxide, alumina, aluminium silicate, and aluminium hydroxide, present in an amount of 28% to 39% w/w.

[014] In an embodiment of the present invention, the composition is formulated as wettable powder. DESCRIPTION OF THE INVENTION

[015] The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. Descriptions of specific applications are provided only as representative examples. The present application is not intended to be limited to the embodiments shown but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

[016] It is to be noted that, as used in the specification, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

[017] Similarly, the words "comprise," "comprises," and "comprising" are to be interpreted inclusively rather than exclusively. Likewise, the terms "include" "including" and "or" should all be construed to be inclusive, unless such a construction is clearly prohibited from the context. However, the embodiments provided by the present disclosure may lack any element that is not specifically disclosed herein. Thus, a disclosure of an embodiment defined using the term "comprising" is also a disclosure of embodiments "consisting essentially of and "consisting of the disclosed components. Where used herein, the term "example, "particularly when followed by a listing of terms, is merely exemplary and illustrative, and should not be deemed to be exclusive or comprehensive. Any embodiment disclosed herein can be combined with any other embodiment disclosed herein unless explicitly indicated otherwise.

[018] As used herein, the terms "herbicide" and "herbicidal active ingredient" refer to an active ingredient that kills, controls, or otherwise adversely modifies the growth of vegetation, particularly undesirable vegetation, such as weeds, when applied in an appropriate amount. [019] 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.

[020] As used herein, a "herbicidally effective amount" may be understood to include an amount of an active ingredient that causes a "herbicidal effect," i.e., an adversely modifying effect including, for instance, a deviation from natural growth or development, killing, regulation, desiccation, growth inhibition, growth reduction, and retardation. It may further mean 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. The terms plants, weeds and vegetation include germinant seeds, emerging seedlings, plants emerging from vegetative propagules and established vegetation

[021] As used herein, applying a herbicide or herbicidal composition may be understood to include delivering it directly to the targeted vegetation or to the locus thereof or to the area where control of undesired vegetation is desired. Methods of application include but are not limited to pre-emergently contacting soil or water, post-emergently contacting the undesirable vegetation or area adjacent to the undesirable vegetation.

[022] As used herein, the terms "crops" and "vegetation" can include, for instance, dormant seeds, germinant seeds, emerging seedlings, plants emerging from vegetative propagules, immature vegetation, and established vegetation.

[023] As used herein, immature vegetation may be understood to include small vegetative plants prior to reproductive stage, and mature vegetation may be understood to include vegetative plants during and after the reproductive stage.

[024] The active compounds within the herbicidal composition according to the invention have potent weedicide activity and can be employed for controlling undesired weeds, vegetation and sedges. [025] 2,4-D is chemically known as 2,4- Dichlorophenoxy acetic acid. Usually 2,4-D is used in its salt form. It is a systemic herbicide which kills most broadleaf weeds by causing uncontrolled growth in them but most grasses such as cereals, lawn turf, and grassland are relatively unaffected. 2,4-D acts by mimicking the action of the plant growth hormone auxin, which results in uncontrolled growth and eventually death in susceptible plants. It is absorbed through the leaves and is translocated to the meristems of the plant. Uncontrolled, unsustainable growth ensues, causing stem curl-over, leaf withering, and eventual plant death. The chemical structure of 2,4-D is

For the purpose of the present invention 2,4 D sodium salt is used in the herbicidal composition.

[026] Glufosinate, chemically known as 2-Amino-4- [hydroxy(methylphosphonoyl)]butanoic acid is also known as also known as phosphinothricin and often sold as an ammonium salt, is a naturally occurring broad-spectrum herbicide produced by several species of Streptomyces soil bacteria. Glufosinate is a non-selective, contact herbicide, with some systemic action. Plants may also metabolize bialaphos, another naturally occurring herbicide, directly into glufosinate. The compound irreversibly inhibits glutamine synthetase, an enzyme necessary for the production of glutamine and for ammonia detoxification, giving it antibacterial, antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis and resulting in plant death. The chemical structure of Glufosinate is For the purpose of the present invention Glufosinate ammonium salt is used in the herbicidal composition.

[027] Chlorimuron ethyl, chemically known as [ethyl 2-(4-chloro-6- methoxypyrimidin-2-ylcarbamoylsulfmoyl) benzoate] is a sulfonylurea herbicide. Sulfonylurea herbicides function by interfering with the bio-synthesis of amino acids including valine, isoleucine and leucine. Chlorimuron ethyl is used to control weeds among agricultural crops including grains. Chlorimuron-ethyl is a postemergence, foliar applied herbicide. It has high aqueous solubility, is non-volatile and, based on its chemical properties, is mobile and can be expected to leach to groundwater. It can be moderately persistent in soil systems but will not usually persist in aquatic systems. The chemical structure of chlorimuron ethyl is

[028] In an embodiment of the invention, the herbicidal composition comprises of 2,4-D or its salt, Glufosinate, Chlorimuron ethyl, and suitable adjuvants.

[029] In an embodiment of the invention, the herbicidal composition comprises of 2,4-D sodium salt present in a range from 40% to 47% (w/w), Glufosinate ammonium present in a range from 10% to 15% (w/w), Chlorimuron ethyl is present in a range from 0.15% to 0.40% (w/w), and suitable adjuvants.

[030] The herbicidal composition in addition to herbicidal actives further contains a support, an adjuvant and/or a surfactant. During application, a common adjuvant can be mixed with the composition.

[031] Suitable adjuvants may be a solid or liquid and are generally a substance commonly used in formulation processing process, for example, natural or regenerated minerals, solvents, dispersing agents, wetting agents, adhesives, thickeners, stabilizers, binders, fertilizers, rheology modifier, buffer and filler.

[032] In an embodiment of the invention, the suitable adjuvants are wetting agent, dispersing agent, rheology modifier, buffer and filler. [033] The herbicidal composition of the present invention may be formulated as Granular composition (GR), Capsule suspension (CS), Dispersible concentrate (DC), Dustable powder (DP), Powder for dry seed treatment (DS), Emulsifiable concentrate (EC), Emulsifiable granule (EG), Emulsion water-in-oil (EO), Emulsifiable powder (EP), Emulsion for seed treatment (ES), Emulsion oil-in-water (EW), Flowable concentrate for seed treatment (FS), Granules (GR), Microemulsion (ME), Oil-dispersion (OD), Oil miscible flowable concentrate (OF), Oil miscible liquid (OL), Oil dispersible powder (OP), Suspension concentrate (SC), Suspension concentrate for direct application (SD), Suspo-emulsion (SE), Water soluble granule (SG), Soluble concentrate (SL), Spreading oil (SO), Water soluble powder (SP), Water soluble tablet (ST), Ultra-low volume (ULV) suspension, Tablet (TB), Ultra-low volume (ULV) liquid, Water dispersible granules (WG), Wettable powder (WP), Water dispersible powder for slurry seed treatment (WS), Water dispersible tablet (WT), a mixed formulation of CS and SC (ZC), a mixed formulation of CS and SE (ZE), a mixed formulation of CS and EW (ZW). Preferably, the composition of the present invention is in form of wettable powder (WP).

[034] Wetting is the first stage of dispersion, in which the air surrounding the granular composition is substituted with water. Wetting of the herbicidal composition with water cannot occur if the surface tension of the liquid is very high. Hence, it is recommended to add a wetting agent to the herbicidal composition to facilitate the process of dispersion of the granules in the liquid. Accordingly, the composition of the present invention preferably contains a wetting agent such as naphthalene alkyl aryl sulphonate, dioctyl sulfosuccinate, sodium lauryl sulfate, non-ionic ethoxylated polyarylphenol phosphate ester, sodium alkyl naphthalene sulfonate or a combination thereof. Preferably, the wetting agent suitable for use in the present invention are dialkyl naphthalene sulphonate sodium salt, alkylnaphthalene sulfonate (ANS) condensate blend, sodium ligno sulphonate, linear alcohol derivative and polyethylene glycol nonyl phenyl ether ammonium sulfate. Wetting agent is present in a range from 4% to 5% (w/w) in the compositions of the present invention. [035] It is generally observed that solid particles in a liquid undergo spontaneous aggregation to form lumps. Hence it is recommended to add a dispersant or a dispersing agent which prevents aggregation of solid particles and keeps them suspended in the fluid. Accordingly, the composition of the present invention preferably contains a dispersing agent such as amine salt of phosphate tristyryl phenol ethoxylated, acrylic copolymer, naphthalene sulphonate of formaldehyde condensate, lignin based sulphonate. One or more dispersing agents may be used in the synergistic composition of the present invention. The dispersing agent suitable for use in the present invention are Sodium salt of polyalkyl naphthalene sulfonate, sodium ligno sulphonate, acrylate copolymer, phenol sulfonic acid- formaldehyde -polycondensation as sodium salt, sodium polycarboxylate, sodium methyl oleoyl taurate and sodium lauryl sulphate or combination thereof. Dispersing agent is present in a range from 4% to 5.5% (w/w) in the compositions of the present invention.

[036] Rheology modifiers are sometimes referred to as thickeners or viscosity modifiers, but they do much more than just thicken a formulation. A good rheology modifier structures the formulation but when a force is applied it becomes flowable and easily poured. Flowable formulations require a rheology modifier to prevent sedimentation phenomena. Rheology modifiers produce a “three-dimensional” gel network in the continuous phase resulting in a non-Newtonian fluid, which provides stability to the formulation. The rheology modifier must give high viscosity, so the product does not separate during long-term storage but still allow the product to be easily poured from the package. The suitable rheology modifier of the present invention is silicon dioxide. Rheology modifiers are suitably present in the range of 1.5% to 2.5% (w./w.).

[037] Buffering agent or buffer is classified as a utility modifier that widens the range of conditions under which a given herbicide formulation is useful. Thus, a buffering agent increases the dispersion and/or solubility of an herbicide under conditions of extreme acidic or alkaline waters. The suitable buffering agents of the present invention are oxalic acid, citric acid, orthophosphoric acid and disodium hydrogen orthophosphate. For the present invention, buffer is suitably present in a range of 0.20% to 0.22% (w./w.) [038] A “filler” refers to solid chemicals that are added to an herbicide formulation to aid in the delivery of the active ingredient. Filler is selected from the group comprising of, but not limited to, natural minerals such as corn starch, lactose monohydrate, quartz, talc, kaolin, pyrophyllite, montmorillonite, attapulgite, bentonite clay, china clay, kieselguhr, chalk, zeolite, calcite, sericite, acid clay, diatomaceous earth, natural rock, Fuller’s earth, meerschaum, gibbsite, dolomite or pumice; synthetic minerals such as precipitated silica, fumed silica, sodium silicate, silicon dioxide, alumina, aluminium silicate, aluminium hydroxide; inorganic salts such as calcium carbonate, ammonium sulfate or other ammonium salts, sodium sulfate, potassium chloride. The filler may be used alone or in combination thereof. Filler is present in a range from 28% to 39% (w/w).

[039] The present invention further relates to methods of controlling unwanted vegetation, including application of a combination of herbicides according to the invention to unwanted vegetation. The application can be carried out before, during and / or after germination of unwanted vegetation, preferably during germination and / or after germination.

[040] The combinations of the present invention can be applied in a conventional manner using techniques familiar to a person skilled in the art. Suitable techniques include spraying, atomizing, spraying, diffusing or irrigating. The mode of application will vary according to the intended purpose in a well-known manner but should ensure the best and possible application of the active ingredient according to the invention.

[041] The herbicide compositions of the present invention can be applied to a variety of undesired vegetation in both residential and commercial plant or crop areas. Preferably, the herbicide compositions are effective to selectively control broadleaf weeds growing in grass and turf areas. The herbicidal compositions disclosed herein are very effective against numerous common broadleaf weeds, mosses, liverworts, and algae. Grass and turf areas that are infested with undesired vegetation can be entirely sprayed with a herbicidal composition of the present invention to selectively remove the unwanted vegetation, while leaving the grass, turf and other desired plants undamaged. [042] The present invention applies, in particular, the combination as defined herein to a crop planting site where unwanted vegetation occurs or may occur, or where the crop is planted, prior to planting or germination of the crop for controlling unwanted vegetation in crops.

[043] The synergistic herbicidal composition of the present invention was found to be non-phytotoxic and has good stability, wettability, suspensibility and dispersibility.

[044] In an embodiment of the invention, the herbicidal composition of the present invention may be mixed with or may be used in combination with other herbicides, fungicides, antibiotics, plant hormones, insecticides, fertilizers, phy to toxicity - reducing agents, etc., in addition to the above active ingredients, without departing from the intention and the scope of the present invention, whereby more excellent effects and activities may sometimes be obtained.

[045] The present invention is more particularly described in the following examples that are intended as illustrations only, since numerous modifications and variations within the scope of the present invention will be apparent to those of skilled in the art. Unless otherwise noted, all parts, percentages, and ratios reported in the following examples are on a weight basis and all reagent used in the example were obtained or are available from the chemical suppliers.

[046] Examples:

[047] Example 1: Preparation of composition of 2,4-D sodium salt, Chlorimuron Ethyl and Glufosinate ammonium in wettable powder form (WP)

[048] Step 1: weighing the raw materials according to the batch size as follows: a. filler, b. wetting agent, c. dispersing agent, d. rheology modifier, e. 2,4-D sodium salt, f. Chlorimuron Ethyl, g. Glufosinate ammonium, and h. optionally buffer. weighing all this raw material in a pre-blender and mixing it for 1 hr;

Step 2: Milling the sample through air jet mill instrument at Inlet pressure 2-3 kg/cm ² , grinding pressure 6 kg/ cm ² and checking the particle size < 15 micron;

Step 3: Collecting the milled material, and post blending the sample for Ihr;

Step 4: Sending the sample to the Quality analysis;

Step 5: Packing the formulated material in a suitable packaging.

[049] Example 2: Compositions of the present invention

The illustrative embodiments show the composition of 2,4-D sodium salt, Chlorimuron Ethyl and Glufosinate ammonium in wettable powder form in different amount as follows:

[050] Table 1: 2,4-D sodium salt 46.4% + Chlorimuron Ethyl 0.36% +

Glufosinate ammonium 15 % (WP) [051] The composition of Table 1 is prepared by following the process:

46.4 gm of 2,4-D sodium salt, 0.36 gm of chlorimuron ethyl, 15.0 gm of glufosinate ammonium, 4.0 gm of alkylnaphthalene sulfonate condensate blend, 2.0 gm of phenol sulfonic acid-formaldehyde, 2.0 gm of sodium poly alkylnaphthalene sulphonate, 1.5 gm of silicon dioxide, and 28.74 gm of china clay were weighed in the pre-blender reactor and are mixed for 1 hour. The mixture was milled through air jet mill instrument (Inlet pressure 2-3 kg/cm ² , grinding pressure 6 kg/ cm ² ) to obtain the desired particle size (D90 < 15 microns). The milled material is collected and post blending the material for 1 hour followed by packing the material in a suitable package.

[052] Table 2: 2,4-D sodium salt 40% + Chlorimuron Ethyl 0.15% +

Glufosinate ammonium 10% (WP) [053] The composition of Table 2 is prepared as following process:

40.0 gm of 2,4-D sodium salt, 0.15 gm of chlorimuron ethyl, 10.0 gm of glufosinate ammonium, 5.0 gm of alkylnaphthalene sulfonate condensate blend, 3.0 gm of phenol sulfonic acid-formaldehyde polycondensation as sodium salt, 1.0 gm of acrylate copolymer, 2.0 gm of silicon dioxide, 0.20 gm of oxalic acid and 38.65 gm of china clay were weighed in the pre -blender reactor and mixed for 1 hour. The mixture was milled through air jet mill instrument (Inlet pressure 2-3 kg/cm ² , grinding pressure 6 kg/ cm ² ) to obtain the desired particle size (D90 < 15 microns).

Collecting the milled material and post blending the material for 1 hour followed by packing the material in a suitable package.

[054] Table 3: 2,4-D sodium salt 42% + Chlorimuron Ethyl 0.20% +

Glufosinate ammonium 12% (WP)

[055] The composition of Table 3 is prepared by following the process described for Table 2.

[056] Table-4: 2,4-D sodium salt 43% + Chlorimuron Ethyl 0.25% +

Glufosinate ammonium 13% (WP)

[057] The composition of Table 4 is prepared by following the process described for Table 2. [058] Table-5: 2, 4-D sodium salt 45% + Chlorimuron Ethyl 0.30% +

Glufosinate ammonium 14% (WP) [059] The composition of Table 5 is prepared by following the process described for Table 2.

[060] Example 3: Efficacy study for combination: 2,4-D sodium salt + Chlorimuron ethyl + Glufosinate ammonium

FIELD AND SYNERGY STUDIES

[061] Weeds compete with the fruit trees for water and nutrients. Therefore, there is a need to control weeds around the tree basin for both young and mature fruit trees. Most weeds complete their life cycle in a shorter period in comparison to fruit trees and compete for light, water and mineral nutrients and reduce yield. Weeds sometimes act as intermediate or alternate hosts to certain pests, diseases which cause heavy losses. In India, yield loss due to weeds is approximately 33 per cent of total production, and on an average 30 per cent of the total production cost is spent on tillage operations alone. Therefore, efficient weed control is necessary for profitable fruit production. Traditionally, weed control in India has been largely dependent on manual weeding. However, increased labour scarcity and costs are encouraging farmers to adopt to use herbicides.

[062] The field studies were conducted to compare the weed controlling activity of the combination of 2,4-D sodium salt, Chlorimuron ethyl and Glufosinate ammonium. The active ingredient 2,4-D sodium salt in the combination, belongs to chemical family “Phenoxy-carboxylates” with mode of action of Auxin mimic group whereas, Chlorimuron ethyl is belonging to chemical family “Sulfonylureas” with ALS inhibitor (inhibition of acetolactate synthase) mode of action. Glufosinate ammonium in the combination belongs to chemical class “Phosphinic acids” with inhibition of Glutamine synthetase mode of action of herbicide. This combination helps in controlling the cross-spectrum weeds (broad leaf weeds, grassy weeds, and sedges) in various fruit orchards when applied in post-emergence application timing. All the molecules were found safe when applied in between the rows of fruit crops.

[063] The weed control activity of the individual herbicides of the invention and their combinations were evaluated on weeds such as Borreria hispida, Imperata cylindrica, Ageratum conyzoides, Cynodon dactylon, Cyperus rotundus, Eleusine indica, Digitaria sanguinalis and Echinochloa colona. Trials were conducted with randomized block design with net plot size of 5m x 6m. Each trial was replicated four times and conducted under GEP guidelines. Spraying was done with manual operated backpack knapsack sprayer with 300 L of water spray volume per hectare in post-emergence application timing of 2 to 4 inches of weed height. Such field trials were carried out at various locations to generate independent data, the locations were chosen randomly across India.

[064] Visual observations were recorded on percent weed control for individual weeds on whole plot basis at 21 days after application. These observations are to be taken from entire plot.

[065] Appropriate analysis of plant response to herbicide combination is critical in determining the type of activity observed. The most widely used model is one Gowing* derived and Colby** modified. Gowing described a mathematical formula for calculating the predicting response values for pesticide mixtures. He suggested the expected (E) percent inhibition of growth induced by pesticide A plus pesticide B and plus pesticide C is as follows, *(Jerry Flint et al, 1988) ***

Where,

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.

[066] When the percentage of pesticidal control observed for the combination is greater than the expected percentage, there is a synergistic effect. (Ratio of O/E > 1, means synergism observed.)

Reference: 'Flowing D. P. 1960. Comments on tests of herbicide mixtures. Weeds 8:379- 391.

**Colby, S. R. 1967. Calculating synergistic and antagonistic responses of herbicide combinations. Weeds 15:20-22 *** Jerry Flint et al, 1988. Analyzing Herbicide Interactions: A Statistical Treatment of Colby's Method. Weed Technology 2: 304-309

[067] The herbicide combinations, application rates, plant species tested, and results are given in the following tables: [068] Table 6: Table 6 demonstrates synergy on weeds using the combination of

2,4-D sodium salt 46.4% + Chlorimuron ethyl 0.36% + Glufosinate ammonium 15% WP. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 21 days of application. The target weeds were Borreria hispida, Imp er at a cylindrica and Ageratum conyzoides and the results are recorded in the table 6 below

WP - Wettable powder and GAH - Gram active per hectare.

[069] The results in table 6 clearly demonstrates synergy between 2,4-D sodium salt 46.4% + Chlorimuron ethyl 0.36% + Glufosinate ammonium 15% WP against weeds like, Borreria hispida, Imp er at a cylindrica and Ageratum conyzoides . The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination.

[070] Table 7: Table 7 demonstrates synergy on weeds using the combination of 2,4-D sodium salt 46.4% + Chlorimuron ethyl 0.36% + Glufosinate ammonium 15% WP. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 21 days of application. The target weeds were Cynodon dactylon and Cyperus rotundus and the results are recorded in the table 7 below. WP - Wettable powder and GAH - Gram active per hectare.

[071] The results in table 7 clearly demonstrates efficacy 2,4-D sodium salt 46.4% + Chlorimuron ethyl 0.36% + Glufosinate ammonium 15% WP against weeds like, Cynodon dactylon and Cyperus rotundus. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination.

[072] Table 8 Table 8 demonstrates synergy on weeds using the combination of 2,4-D sodium salt 46.4% + Chlorimuron ethyl 0.36% + Glufosinate ammonium 15% WP. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 21 days of application. The target weeds were Eleusine indica, Digitaria sanguinalis and Echinochloa colona and the results are recorded in the table 8 below.

WP - Wettable powder and GAH - Gram active per hectare. [073] The results in table 8 clearly demonstrates efficacy of 2,4-D sodium salt 46.4% + Chlorimuron ethyl 0.36% + Glufosinate ammonium 15% WP against weeds like Eleusine indica, Digitaria sanguinalis and Echinochloa colona. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination.

[074] The combinations of the present invention have several advantages over solo application of either glufosinate, 2,4-D or its sodium salt or chlorimuron ethyl, and, likewise, over any binary combination of these herbicides. The combination of the present invention shows enhanced herbicide action in comparison with the herbicide action of solo action of glufosinate, 2,4-D or its salt or Chlorimuron ethyl against undesirable vegetation. Moreover, the combinations of the invention show a persistent herbicidal activity, even under difficult weathering conditions, and minimizes the risk of weeds escaping. The combinations are generally non-toxic or of low toxicity against mammals. Apart from that, the combinations of the present invention show superior crop compatibility with certain conventional crop plants and with herbicide tolerant crop plants, i.e., their use in these crops leads to a reduced damage of the crop plants and/or does not result in increased damage of the crop plants. Thus, the combinations of the invention can also be applied after the emergence of the crop plants. The combinations of the present invention may also show an accelerated action on harmful plants, i.e., they may effect damage of the harmful plants more quickly in comparison with solo or binary applications of the at least three herbicides involved.

[075] From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the scope of the novel concepts of the present invention. It is to be understood that no limitations with respect to the specific embodiments illustrated is intended or should be inferred. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.