DESC:FIELD OF THE INVENTION
[001] The present invention relates to a herbicidal composition for protecting crops against weeds, undesired vegetation and grasses. More, particularly, the present invention relates to the herbicidal composition comprising a mixture of triazines, particularly metribuzin and atrazine and sulfonyl urea, particularly pyrazosulfuron ethyl. The present invention further relates to a method of controlling weeds comprising applying a composition of the present invention to the weeds or an area in need of weed control.
BACKGROUND OF THE INVENTION
[002] Unwanted plants, such as weeds, reduce the number of resources available to crop plants and can have a negative effect on crop plant yield and quality. The control of unwanted vegetation is a continually important effort as it is needed for reducing health problems, such as allergies, the removal of poisonous/noxious weeds, increasing crop productivity, as well as improving the general aesthetics around the home. Unwanted vegetation can be controlled using herbicides that are either selective or non-selective. Non-selective herbicides kill or damage all plants to which they are applied, i.e., both desired and undesired vegetation. In contrast, selective herbicides eliminate or inhibit the growth of unwanted vegetation, while leaving the desired vegetation relatively unharmed. Contact herbicides are applied to the top growth, or portion(s) of the plant located above the soil surface. These herbicides, which kill or damage the top-growth only, are typically effective on annual weeds or vegetation. In contrast, systemic herbicides are initially taken up by the roots and/or the foliage of the plant and subsequently translocated to tissues that are remotely located from the point of application.
[003] The herbicidal effectiveness of a compound cannot be predicted from an examination of the substituent groups of the compound and often quite closely related compounds possess different weed control abilities. Various herbicides of the same class of compounds may have complementary areas of activity and thus can be useful to control a variety of weeds upon application of a combination. Furthermore, the various herbicides are not completely effective so as to control all the infesting weeds in a field crop, which necessitates the use of herbicidal combinations. An ideal herbicide should afford selective weed control, over the full growing season, with a single administration. It should be able to control all common weeds by controlling their growth and reproduction as the seed, the germinating seed, the seedling and the growing weed plant. It is often imperative to use herbicidal combinations to achieve these advantages, although the selection of the components of an ideal combination is not a straightforward choice for a skilled artisan.
[004] Thus, there is a long felt need for a highly active and long-residual herbicidal composition with which the dose of the active ingredient can be reduced and having a broad-spectrum effect.

SUMMARY OF THE INVENTION
[005] The present invention provides a herbicidal composition comprising a a mixture of triazines, particularly metribuzin and atrazine and sulfonyl urea, particularly pyrazosulfuron ethyl.
[006] In an embodiment of the present invention, metribuzin is present in a range from 10% (w/w) to 25% (w/w); and atrazine is present in a range from 30% (w/w) to 50% (w/w) and pyrazosulfuron ethyl is present in a range from 0.30% (w/w) to 1.2% (w/w).
[007] 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.
[008] 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.
[009] In an embodiment of the present invention, the dispersing agent is selected from the group comprising 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, present in a range from 4% to 5.5% w/w.
[010] 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.
[011] 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.
[012] 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 14% to 43% w/w.
[013] In an embodiment of the present invention, the composition is formulated as wettable powder.

DESCRIPTION OF THE INVENTION

[014] 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.
[015] 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.
[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] The term “active ingredient” (a.i.) or “active agent” used herein refers to that component of the composition responsible for control of weeds, undesired vegetation and grasses.
[018] 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.
[019] 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. The terms plants, weeds and vegetation include germinant seeds, emerging seedlings, plants emerging from vegetative propagules and established vegetation.
[020] The present invention aims provide a herbicidal combination, which allows efficient and reliable control of grass and broadleaf weeds. Moreover, the persistence of the herbicidal activity of the combination should be sufficiently long in order to achieve control of the weeds over a sufficient long time period thus allowing a more flexible application. The combination should also have a low toxicity to humans or other mammals. The combinations should also show an accelerated action on harmful plants, i.e., they should effect damaging of the harmful plants more quickly in comparison with application of the individual herbicides.
[021] Metribuzin, chemically known as 4-amino-6-tert-butyl-3-methylsulfanyl-1,2,4-triazin-5-one has chemical structure as below.

[022] Metribuzin is a triazinone herbicide that inhibits photosynthesis in a susceptible plant by binding to a protein of the photosystem II complex, which in turn, cause a chain of events where, eventually, plant lipids and proteins are attacked and oxidized by highly reactive free radicals. As a result, chlorophyll and plant pigments are lost causing chlorosis followed by plant cell drying and disintegration. When applied to soil, metribuzin is readily absorbed by roots, after which translocation upward to the shoots and beyond occurs through the xylem. Once susceptible plants emerge through treated soil into the sunlight, they become yellow/chlorotic, then totally brown after 2 to 5 days. Microbial breakdown is the main means of metribuzin degradation in the soil. Soil absorption decreases as pH increases, which makes the herbicide more available for degradation. Metribuzin half-life in soils under optimum degradation conditions can be 14 to 28 days.
[023] Atrazine, IUPAC name is 6-Chloro-N2-ethyl-N4-(propan-2-yl)-1,3,5-triazine-2,4-diamine is a widely used herbicide that can be applied before and after planting to control broadleaf and grassy weeds. Atrazine is a member of the triazine chemical class, which includes simazine and propazine. Atrazine is represented by the following structure.

[024] It is used primarily in agriculture, with the greatest use on corn, sorghum, and sugarcane. Atrazine interferes with photosynthesis in some broadleaf plants and grasses. It is taken up by roots and leaves and moves upward in the plant to areas of new growth. The plant dries out and dies. Older leaves on plants may be affected more than new leaves. Root growth is not affected by atrazine. Atrazine is broken down slowly by water, sunlight, and microorganisms. Atrazine has a half-life of 168 days in water exposed to sunlight. Atrazine has a low to moderate solubility in water. Atrazine does not bind well to soil and can easily move in it.
[025] Pyrazosulfuron ethyl, chemically known as (ethyl5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole- 4-carboxylate) is a post-emergence sulfonylurea herbicide for the control of annual and perennial grasses and broad-leaved weeds in rice production. The molecular structure of pyrazosulfuron ethyl is presented as

[026] Pyrazosulfuron ethyl shows outstanding efficacy against broad spectrum of annual and perennial broad leaf weeds and sedges with pre-emergence and post emergence applications at low use rates with an ample margin of crop safety for major rice varieties. The herbicide pyrazosulfuron ethyl has both foliar and soil activity. It is generally recommended as a pre-emergence herbicide in trans-planted rice.
[027] 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.
[028] 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.
[029] In one aspect, the present invention provides a herbicidal combination comprising at least two triazine herbicides in combination with a third herbicide. In one aspect, the present invention may provide a combination comprising metribuzin, atrazine and at least a third herbicide.
[030] In another aspect, the present invention provides a method of controlling weeds at a locus by treating the locus with a combination comprising metribuzin, atrazine and at least a third herbicide pyrazosulfuron ethyl.
[031] In another aspect, the present invention composition may contain an additional herbicide, fungicides, antibiotics, plant hormones, insecticides, fertilizers, phytotoxicity-reducing agents, etc., in addition to actives metribuzin, atrazine and pyrazosulfuron ethyl.
[032] In another aspect, the present invention provides a herbicidal composition comprising metribuzin, atrazine and pyrazosulfuron ethyl in effective amounts and adjuvants.
[033] In another aspect, the herbicidal composition comprises of
metribuzin in a range from 10% (w/w) to 25% (w/w),
atrazine in a range from 30% (w/w) to 50% (w/w),
pyrazosulfuron ethyl in a range from 0.30% (w/w) to 1.2% (w/w),
and adjuvants
[034] Suitable adjuvants may be a solid or liquid and are generally a substance commonly used in formulation processing process, for example, wetting agents, dispersing agents, rheology modifier, buffer and filler.
[035] The novel 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), Micro-emulsion (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 formulated as wettable powder (WP).
[036] Wetting is the first stage of dispersion, in which air surrounding the granular composition is substituted with water. Wetting of the 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 composition to facilitate the process of dispersion of the granules in the liquid. The wetting agent is selected from the group comprising of 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 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.
[037] It is generally observed that solid particles in a liquid undergo spontaneous aggregation to form lumps. Hence it is recommended to add a dispersing agent which prevents agglomeration of solid particles and keep them suspended in fluid.
Accordingly, the composition of the present invention contains dispersing agents such as amine salt of phosphate tristyryl phenol ethoxylated, acrylic copolymer, naphthalene sulphonates 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 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.
[038] 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.).
[039] 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 selected from 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.)
[040] As used herein, the term “filler” refers to solid chemicals that are added to a 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, 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. Preferably, the filler suitable for use in the present invention is china clay. Preferably, filler is present in a range from 14% to 43% w/w.
[041] In another aspect, the present invention provides a method of selectively controlling the broadleaf weeds and grass infestation at a locus, said composition comprising herbicidally effective amount of a combination comprising metribuzin, atrazine and pyrazosulfuron ethyl. Broad leaf weed being selected from chickweed, dandelion, florida betony, japenese clover, plantain, common vetch, Echinochloa Beauvois, Cyperus difformis, Cyperus rotundus (sedge), Cynodon dactylon, Digitaria sanguinalis, Dinebra retroflexa, Eleusine indica, Panicum spp., Dactyloctenium aegyptium (among grasses) Chenopodium album, Trianthema portulacastrum, Trianthema monogyna, convolvulus arvensis, Amaranthus viridis, A blitum, Digera arvensis, Portulaca oleracea, Lactuca runcinata, Euphorbia hirta, Euphorbia geniculata, Eclipta alba, Commelina benghalensis, Digera arvensis, Phyllanthus niruri and sedges in rice and paddy fields etc.
[042] 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.
[043] The present compositions can be applied to the undesirable vegetation and/or weeds or their locus by the use of conventional ground or aerial dusters, sprayers, and granule applicators, by addition to irrigation or paddy water, and by other conventional means known to those skilled in the art.
[044] The present invention is further illustrated by the following examples which are provided merely to be exemplary of the inventions and is not intended to limit the scope of the invention. Certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.
[045] Examples:
[046] Example 1: Process of preparation of composition of Metribuzin, Atrazine and Pyrazosulfuron ethyl in Wettable Powder form.
The composition of Metribuzin, Atrazine, and Pyrazosulfuron ethyl, in wettable powder form is prepared by following steps as below:
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. Metribuzin
f. Pyrazosulfuron ethyl
g. Atrazine,
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/cm2, grinding pressure 6 kg/ cm2 and checking for the particle size < 15 micron.
Step 3: Collecting the Milled material, and post blending the sample for 1hr.
Step 4: Sending the sample to the Quality analysis.
Step 5: Pack the formulated material in a suitable packaging.

[047] Example 2: Compositions of the present invention
[048] The illustrative embodiments show the composition of Metribuzin, Atrazine, and Pyrazosulfuron ethyl in wettable powder form in different amount as follows:
[049] Table 1: Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP
S. No Composition Function % (w/w)
1 Metribuzin Active ingredient 25.0
2 Pyrazosulfuron ethyl Active ingredient 1.17
3 Atrazine Active ingredient 50.0
4 Alkylnaphthalene sulfonate condensate blend Wetting agent 4.0
5 Phenol sulfonic acid-formaldehyde Dispersing agent 2.0
6 Sodium poly alkylnaphthalene sulphonate Dispersing agent 2.0
7 Silicon dioxide Rheology modifier 1.5
8 China clay Filler 14.33
Total 100

[050] Process for manufacture of composition of Table 1 is as follows: 25.0 gm of metribuzin, 1.17 gm of pyrazosulfuron ethyl, 50.0 gm of atrazine, 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 14.33 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/cm2, grinding pressure 6 kg/ cm2) 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.

[051] Table 2: Metribuzin 20% + Pyrazosulfuron ethyl 0.35% + Atrazine 30% WP
S. No Composition Function % (w/w)
1 Metribuzin Active ingredient 20.0
2 Pyrazosulfuron ethyl Active ingredient 0.35
3 Atrazine Active ingredient 30.0
4 Alkylnaphthalene sulfonate condensate blend Wetting agent 5.0
5 phenol sulfonic acid-formaldehyde-polycondensation as sodium salt Dispersing agent 3.0
6 Acrylate copolymer Dispersing agent 1.0
7 Silicon dioxide Rheology modifier 2.0
8 Oxalic acid Buffer 0.20
9 China clay Filler 38.45
Total 100

[052] Process for manufacture of composition of Table 2 is as follows: 20.0 gm of metribuzin, 0.35 gm of pyrazosulfuron ethyl, 30.0 gm of atrazine, 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 38.45 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/cm2, grinding pressure 6 kg/ cm2) 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.
[053] Table 3: Metribuzin 10% + Pyrazosulfuron ethyl 0.50% + Atrazine 35% WP
S. No Composition Function % (w/w)
1 Metribuzin Active ingredient 10.0
2 Pyrazosulfuron ethyl Active ingredient 0.50
3 Atrazine Active ingredient 35.0
4 Dialkyl naphthalene sulphonate sodium salt Wetting agent 4.5
5 Sodium salt of methyl naphthalene sulfonate Dispersing agent 2.5
6 phenol sulfonic acid-formaldehyde-polycondensation as sodium salt Dispersing agent 2.5
7 Silicon dioxide Rheology modifier 1.8
8 Oxalic acid buffer 0.22
9 China clay Filler 42.98
Total 100

[054] Process for manufacture of composition of Table 3 is as follows: 10.0 gm of metribuzin, 0.50 gm of pyrazosulfuron ethyl, 35.0 gm of atrazine, 4.5 gm of Dialkyl naphthalene sulphonate sodium salt, 2.5 gm of Sodium salt of methyl naphthalene sulfonate, 2.5 gm of phenol sulfonic acid-formaldehyde-polycondensation as sodium salt, 1.8 gm of silicon dioxide, 0.22 gm of oxalic acid and 42.98 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/cm2, grinding pressure 6 kg/ cm2) 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.

[055] Table 4: Metribuzin 15% + Pyrazosulfuron ethyl 0.9% + Atrazine 40% WP
S. No. Composition Function % (w/w)
1 Metribuzin Active ingredient 15.0
2 Pyrazosulfuron ethyl Active ingredient 0.9
3 Atrazine Active ingredient 40.0
4 Linear Alcohol Derivative Wetting agent 4.5
5 Sodium polycarboxylate Dispersing agent 2.5
6 Sodium Methyl Oleoyl Taurate Dispersing agent 3.0
7 Silicon dioxide Rheology modifier 2.5
8 Oxalic acid buffer 0.20
9 China clay Filler 31.40
Total 100

[056] Process for manufacture of composition of Table 4 is as follows: 15.0 gm of metribuzin, 0.9 gm of pyrazosulfuron ethyl, 40.0 gm of atrazine, 4.5 gm of Linear Alcohol Derivative, 2.5 gm of Sodium polycarboxylate, 3.0 gm of Sodium Methyl Oleoyl Taurate, 2.5 gm of silicon dioxide, 0.20 gm of oxalic acid and 31.40 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/cm2, grinding pressure 6 kg/ cm2) 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.

[057] Table 5: Metribuzin 20% + Pyrazosulfuron ethyl 1.10% + Atrazine 45% WP
S. No Composition Function % (w/w)
1 Metribuzin Active ingredient 20.0
2 Pyrazosulfuron ethyl Active ingredient 1.1
3 Atrazine Active ingredient 45.0
4 Polyethylene glycol Nonyl phenyl ether ammonium sulfate Wetting agent 5.0
5 Sodium Ligno sulphonate Dispersing agent 3.0

6 Sodium lauryl sulphate Dispersing agent 1.0
7 Silicon dioxide Rheology modifier 2.5
8 Oxalic acid Buffer 0.21
9 China clay Filler 22.19
Total 100

[058] Process for manufacture of composition of Table 5 is as follows: 20.0 gm of metribuzin, 1.1 gm of pyrazosulfuron ethyl, 45.0 gm of atrazine, 5.0 gm of Polyethylene glycol Nonyl phenyl ether ammonium sulfate, 3.0 gm of Sodium Ligno sulphonate, 1.0 gm of Sodium lauryl sulphate, 2.5 gm of silicon dioxide, 0.21 gm of oxalic acid and 22.19 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/cm2, grinding pressure 6 kg/ cm2) 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.
[059] Example 3: Efficacy study for combination: Metribuzin + Pyrazosulfuron ethyl + Atrazine
[060] FIELD AND SYNERGY STUDIES
[061] Sugarcane is an important cash crop of India. In India, it is grown on an area of 48.57 lakh ha with an annual production of 399.25 million tonnes (*Source - E&S, DAC, New Delhi, 4th Adv. Est.-2020-21). Successful weed control is most important factor for fruitful sugarcane production because losses due to weeds have been one of the major limiting factors in sugarcane production. Weeds compete with crop for light moisture and nutrients. Being a slow growing & long duration crop, faces severe weed competition during crop growth, resulting in a loss of about 30-35% of the potential yield. 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 Metribuzin, Atrazine & Pyrazosulfuron ethyl. The active ingredient Metribuzin & Atrazine in the combination, belongs to chemical family “Triazinones” with mode of action of inhibition of photosynthesis at PSII synthesis (PSII) inhibitors and Pyrazosulfuron ethyl belongs to chemical family “Sulfonylureas” with Acetolactate synthase (ALS inhibitor) mode of action. This combination helps in controlling the cross-spectrum weeds (broad leaf weeds, grassy weeds, and sedges) in sugarcane when applied in post-emergence application timing at 2-4 weed leaf stage. All the molecules are safe to sugarcane.
[063] The weed control activity of the individual herbicides of the invention and their combinations were evaluated on weeds such as Cyperus rotundus, Parthenium hysterophorus, Dactyloctenium aegyptium, Echinochloa colona and Dinebra retroflexa. 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 at post-emergence (2-4 weed leaf stage) application timing. 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 30 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:
*Gowing, 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 Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 30 days of application. The target weeds were Cyperus rotundus, Parthenium hysterophorus and Amaranthus viridis and the results are recorded in the table 6 below.
Active Dose (GAH) % Weed Control of Cyperus rotundus % Weed Control of Parthenium hysterophorus % Weed Control of Amaranthus viridis
Expected Observed Expected Observed Expected Observed
Metribuzin 750 15 70 70
Atrazine 1500 10 60 65
Pyrazosulfuron ethyl 35 60 10 20
Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP 750 + 1500 + 35 69.4 78 89.2 95

91.6 95
Ratio of O/E 1.12 1.07 1.04
WP – Wettable Powder and GAH – gram active per hectare.
[069] The results in table 6 clearly demonstrates synergy between Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP against weeds like, Cyperus rotundus, Parthenium hysterophorus and Amaranthus viridis. 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 Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 30 days of application. The target weeds were Dinebra retroflexa ,Dactyloctenium aegyptium, and Echinochloa colona and the results are recorded in the table 7 below.
Active Dose (GAH) % Weed Control of Dinebra retroflexa % Weed Control of Dactyloctenium aegyptium % Weed Control of Echinochloa colona
Expected Observed Expected Observed Expected Observed
Metribuzin 750 75 70 72
Atrazine 1500 20 15 15
Pyrazosulfuron ethyl 35 10 10 10
Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP 750 + 1500 + 35 82 85 77 82
78.6
82
Ratio of O/E 1.04 1.06 1.04
WP – Wettable Powder and GAH – gram active per hectare.
[071] The results in table 7 clearly demonstrates efficacy Metribuzin 25% + Pyrazosulfuron ethyl 1.17% + Atrazine 50% WP against weeds like, Dinebra retroflexa, Dactyloctenium aegyptium, and Echinochloa colona. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination.
[072] As show in the efficacy examples the combinations of the present invention have several advantages over solo application of these herbicides. The combination of the present invention shows enhanced herbicide action in comparison with the herbicide action of solo action of pyrazosulfuron ethyl, metribuzin and atrazine against undesirable vegetation. The combinations are generally non-toxic or of low toxicity against mammals and reduce environmental load.
[073] Although the present invention has been described and illustrated with respect to preferred embodiments and a preferred use thereof, it is not to be so limited since modifications and changes can be made therein which are within the full scope of the invention. ,CLAIMS:1. An herbicidal composition comprising a mixture of triazines and a sulfonyl urea in effective amounts and adjuvants.
2. The herbicidal composition as claimed in claim 1, wherein the mixture of triazines comprises of metribuzin and atrazine and the sulfonyl urea is pyrazosulfuron ethyl.
3. The herbicidal composition as claimed in claim 1, wherein the metribuzin is present in a range from 10% (w/w) to 25% (w/w); atrazine is present in a range from 30% (w/w) to 50% (w/w); and pyrazosulfuron ethyl is present in a range from 0.30% (w/w) to 1.2% (w/w).
4. The herbicidal composition as claimed in claim 1, wherein the adjuvants are selected from a wetting agent, a dispersing agent, a rheology modifier, a buffer, and a filler.
5. The herbicidal composition as claimed in claim 4, wherein 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.
6. The herbicidal composition as claimed in claim 4, wherein 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.
7. The herbicidal composition as claimed in claim 4, wherein the rheology modifier is silicon dioxide, present in a range from 1.5% to 2.5% w/w.
8. The herbicidal composition as claimed in claim 4, wherein 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.
9. The herbicidal composition as claimed in claim 4, wherein 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, calcium carbonate, alumina, aluminium silicate, and aluminium hydroxide, present in an amount of 14% to 43% w/w.
10. The herbicidal composition as claimed in claim 1, wherein the composition is formulated as wettable powder.