WO2016125188A1

WO2016125188A1 - Title: synergistic herbicidal composition of pendimethalin and metribuzin

Info

Publication number: WO2016125188A1
Application number: PCT/IN2016/050039
Authority: WO
Inventors: Ajit Singh Gujral; Kenal V. Shah; Bhavesh V. Shah; Arvind DR. SINGH; Dipakkumar Patel
Original assignee: Gsp Crop Science Pvt. Ltd.
Priority date: 2015-02-03
Filing date: 2016-02-03
Publication date: 2016-08-11
Also published as: WO2016125188A4

Abstract

The present invention relates to synergistic herbicidal composition of Pendimethalin and Metribuzin present in bioactive amounts. The invention also relates to the process for the preparation of the said composition containing bioactive amounts of Pendimethalin and Metribuzin. The present invention also relates to the use as a pre-emergence and early post-emergence herbicide against weeds of wheat, potato and maize crops infested by Phalaris minor, Avena fatua, Echinochloa colonum, Digitaria sanguinalis, Dactyloctenium aegyptium, Brachiaria mutica, Chenopodium album, Melilotus indica, Medicago sativa, Trianthema monogyna, Digera arvensis, Commelina spp., Rumex spp.,and other annual Grassy and broad leaf weeds with synergistic effect.

Description

TITLE: SYNERGISTIC HERBICIDAL COMPOSITION OF PENDIMETHALIN AND METRIBUZIN

FIELD OF THE INVENTION:

The present invention relates to synergistic herbicidal composition of Pendimethalin and Metribuzin present in bioactive amounts. The invention also relates to the process for the preparation of the said composition containing bioactive amounts of Pendimethalin and Metribuzin. The present invention also relates to the use as a pre-emergence and early post -emergence herbicide against weeds of wheat, potato and maize crops infested by Phalaris minor, Avena fatua Echinochloa, colonum Digitaria sanguinalis, Dactyloctenium aegyptium, Brachiaria mutica, Chenopodium album, Melilotus indica, Medicago sativa, Trianthema monogyna, Digera arvensis, Commelina spp., Rumex spp.,and other annual Grassy and broad leaf weeds with synergistic effect.

BACKGROUND OF THE INVENTION

Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets, while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic mimics of natural plant hormones. Herbicides can be classified based on activity, use, chemical family, mode of action, or type of vegetation controlled.

By activity:

Contact herbicides: They destroy only the plant tissue in contact with the chemical. Generally, these are the fastest acting herbicides. They are less effective on perennial plants, which are able to regrow from rhizomes, roots or tubers.

Systemic herbicides: They are translocated through the plant, either from foliar application down to the roots, or from soil application up to the leaves. They are capable of controlling perennial plants and may be slower-acting, but ultimately more effective than contact herbicides.

By use:

Soil-applied herbicides: They are applied to the soil and are taken up by the roots and/or hypocotyl of the target plant. The three main types are: Preplant incorporated herbicides: They are soil applied prior to planting and mechanically incorporated into the soil. The objective for incorporation is to prevent dissipation through photodecomposition and/or volatility.

Pre-emergent herbicides: They are applied to the soil before the crop emerges and prevent germination or early growth of weed seeds.

Post-emergent herbicides: They are applied after the crop has emerged.

Their classification by mechanism of action (MO A) indicates the first enzyme, protein, or biochemical step affected in the plant following application. The main mechanisms of action are:

ACCase inhibitors compounds kill grasses. Acetyl coenzyme A carboxylase (ACCase) is part of the first step of lipid synthesis. Thus, ACCase inhibitors affect cell membrane production in the meristems of the grass plant. The ACCases of grasses are sensitive to these herbicides, whereas the ACCases of dicot plants are not.

ALS inhibitors: the acetolactate synthase (ALS) enzyme (also known as acetohydroxyacidsynthase, or AHAS) is the first step in the synthesis of the branched-chain amino acids (valine, leucine, and isoleucine). These herbicides slowly starve affected plants of these amino acids, which eventually leads to inhibition of DNA synthesis. They affect grasses and dicots alike. The ALS inhibitor family includes sulfonylureas, imidazolinones, triazolopyrimidines, pyrimidinyloxybenzoates, and sulfonylamino carbonyl triazolinones. The ALS biological pathway exists only in plants and not animals, thus making the ALS -inhibitors among the safest herbicides.

EPSPS inhibitors: The enolpyruvylshikimate 3-phosphate synthase enzyme EPSPS is used in the synthesis of the amino acids tryptophan, phenylalanine and tyrosine. They affect grasses and dicots alike. Glyphosate (Roundup) is a systemic EPSPS inhibitor inactivated by soil contact.

Synthetic auxins inaugurated the era of organic herbicides. They were discovered in the 1940s after a long study of the plant growth regulator auxin. Synthetic auxins mimic this plant hormone. They have several points of action on the cell membrane, and are effective in the control of dicot plants. 2,4- D is a synthetic auxin herbicide.

Photosystemll inhibitors reduce electron flow from water to NADPH2+ at the photochemical step in photosynthesis. They bind to the Qb site on the Dl protein, and prevent quinone from binding to this site. Therefore, this group of compounds causes electrons to accumulate on chlorophyll molecules. As a consequence, oxidation reactions in excess of those normally tolerated by the cell occur, and the plant dies. The triazine herbicides (including atrazine) and urea derivatives (diuron) are photosystem II inhibitors.

Photosystem I inhibitors steal electrons from the normal pathway through FeS - Fdx - NADP leading to direct discharge of electrons on oxygen. As a result, reactive oxygen species are produced and oxidation reactions in excess of those normally tolerated by the cell occur, leading to plant death.

Pendimethalin, chemically known as N-(l-ethylpropyl)-2,6-dinitro-3,4-xylidine and having chemical structure as below;

Pendimethalin is a selective herbicide, absorbed by the roots and leaves. Affected plants die shortly after germination or following emergence from the soil.

Pendimethalin is used to control of most annual grasses and many annual broad-leaved weeds at 0.4- 2.0 kg a.i./ha in cereals, onions, leeks, garlic, fennel, maize, sorghum, rice, soya beans, peanuts, brassicas, carrots, celery, black salsify, peas, field beans, lupins, evening primrose, tulips, potatoes, cotton, hops, pome fruit, stone fruit, berry fruit (including strawberries), citrus fruit, lettuce, aubergines, capsicums, established turf, and in transplanted tomatoes, sunflowers, and tobacco, applied pre-plant incorporated, pre-emergence, pre-transplanting, or early post-emergence. Also, Pendimethalin is used for control of suckers in tobacco. Pendimethalin is used by farmers to control a wide variety of weeds. Pendimethalin plays an important role in weed management for numerous major crops such as rice, wheat, maize and soybean as well as minor crops such as fruits and vegetables. Pendimethalin is available in USA market as Pendulin® 2G Granules and Pendulum® AquaCap™ Further Pendimethalin is also available as EC formulation, SC formulation and CS formulation.

Indian patent application 768/MUM/2000, describes improved process of manufacturing herbicidal composition comprising the following steps: Step 1 : Preparation of the slurry with Metribuzin powder and adjuvants and fillers as per our formula. Step 2: Mixing of the water to make homogenous slurry. Step 3: Grinding with correct media size and strength to get the range of particle size as required for the efficient bioefficacy. Step 4: Removal of moisture and first stage of granulation. Step 5: Further second stage granulation to achieve bigger granules as combination of Raspberry type and onion skin type. Step 6: Removal of fine dust and recycling the same into the dryer. Step 7: The standard air with very little fines is passed through a venturi and/or a packed column. Step 8 : The finished product is collected and bagged or packed as required. Indian patent application 2178/KOLNP/201 ldiscloses aqueous flowable concentrate compositions of a microencapsulated dinitroanline herbicide, in particular pendimethalin, which are flow-able and have improved storage stability.

Indian patent application 2251 /MUM/2011 describes a capsule suspension formulation comprising pendimethalin in combination with clomazone. More particularly, the present invention relates to a storage stable, improved non-staining and non-volatile capsule suspension formulation comprising pendimethalin in combination with clomazone.

Indian patent application 2792/CHENP/2006disclosesemulsifiableconcentrates comprising an active ingredient being a dinitroanifine compound, preferably selected from the group consisting of pendimethalin, trifluralin and mixtures thereof, an emulsifier or an emulsifier mixture, and a solvent.

Indian patent application 284/MUM/2010 relates to a capsule suspension formulation comprising pendimethalin. More particularly, the present invention relates to a storage stable, improved non- staining capsule suspension formulation comprising pendimethalin.

Further the staining nature of pendimethalin creates a challenge to preparing the formulation which minimizes the staining during manufacturing process of the composition as well as during the end use. Metribuzin, chemically known as 4-amino-6-tert-butyl-3-methylsulfanyl-l,2,4-triazin-5-one and having chemical structure as below;

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. Herbicides with this mechanism of action are referred to in the literature as group 5, photosystem inhibitor. 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. Chemical degradation by hydrolysis is does not occur between soil pH 5 to 9. Metribuzin half-life in soils under optimum degradation conditions can be 14 to 28 days. However persistence is increased with cool temperature and low soil moisture conditions since both microbial and chemical degradation are limited in those circumstance.

Karakotov S Det al {Novel formulation for enhancing efficiency of metribuzin: Commun Agric Appl Biol Sci. 2006;71(2 Pt A):31-7.) had studied the biological efficiency of systemic herbicide metribuzin in water dispersible granules (WG) and solution colloid concentrate (SCC) formulations was studied in field experiments. Metribuzin formulation in SCC state was prepared by the addition of a mixture of anionic and non-ionic surfactants and alkoxylated sorbitan esters as specific adjuvants. The ability of herbicide formulation containing Metribuzin in SCC state to provide increases in control of broadleaf and grassy weeds in comparison to WG was observed. The possibility to reduce application rate of Metribuzin from high-dose to low-dose without losing efficacy of weed control was demonstrated.

Metribuzin is available in Emulsifiable concentrate (EC), 14-15%; flowable concentrate (FC), 41%; water dispersable granules (dry flowable) 64.3 to 75%; wettable powder, 50 to70%.

Indian patent application 538/DEL/2010 describes herbicidal composition and a process for preparing the same. More particularly, the present invention pertains to a homogenous wettable powder form of herbicidal composition comprising prop-2-ynyl(R)-2-l4-(5-chloro-3-fluoro-2-pyridyloxy) phenoxy] propionate (commonly known as Clodinafop-propargyl) and 4-amino-6-tert-butyl-4,5-dihydro-3- methylthio-l,2,4-triazin-5-one (commonly known as Metribuzin). Indian patent application 696/DEL/2011 discloses a liquid herbicidal emulsifiable concentrate comprising (a) the herbicidal active substance metribuzin, (b) one or more herbicidal active substances selected from the group consisting of the ACCase inhibitors (bl), (b2) and (b3): (bl) esters of fenoxaprop-P and esters of fenoxaprop, (b2) esters of clodinafop, (b3) pinoxaden, (c) optionally other active ingredients, which do not substantially interfere with the stability of the co-formulation, (d) one or more non-polar organic solvent, (e) one or more polar organic co-solvent, (f) one or more non-ionic emulsifiers, (g) one or more anionic emulsifiers, and (h) optionally further formulation auxiliaries.

US patent no. 6071858discloses a stable dry composition of herbicides where N-(4-fluorophenyl)-N- (l-methylethyl)-2[[5-(trifluoromethyl)-l,3,4-thiadiazol-2-yl]oxy]acetamide, also known as "Fluthiamide" or "Flufenacet," and 4-amino-6-(l,l-dimethylethyl)-3-(methylthio)-l,2,4-triazin-5- (4H)-one, also known as "Metribuzin," are two selective herbicides, which are highly effective against a range of broadleaf and grassy weeds found in corn and soybeans. In the said composition these two pesticides is to dissolve in a solvent and then intermix this solution with an aqueous lignosulfonate solution to obtain an emulsion from which the solvent and water are evaporated leaving a dry powder containing a mixture of fine particles of the pesticide intermixed intimately with the lignosulfonate.

Metribuzin is herbicide used both pre- and post-emergence in crops including soy bean, potatoes, tomatoes and sugar cane. It acts by inhibiting photosynthesis by disrupting photosystem II.

However there is still need for the effective and synergistic composition with herbicidal effect and also is comparatively easy to manufacture as large scale and overcome the problems described in the prior arts. In general use, the herbicides are used in the form of a dilute aqueous composition because it can attain a good interaction with the target organism, such as plants, fungi and insects. However, most active herbicidal compounds that are used as herbicide are only sparingly or even insoluble in water. The low solubility of such compounds present the challenges and difficulties to formulator in formulating pesticide compounds in stable formulations that can be easily stored for a long time and which still have a high stability and effective activity until end use. This problem especially occurs and may get worsen if more than one active compound is present in the composition and further if any of the active is having certain characteristics like highly staining as like in pendimethalin, if further add in to the challenge. For the reasons mentioned above there is a need to provide a synergistic herbicidal composition of two actives, Pendimethalin and Metribuzin. This object is achieved according to the invention by providing the present composition as described.

OBJECT OF THE INVENTION In an object of the present invention is enclosed synergistic herbicidal composition of Pendimethalin and Metribuzin present in bioactive amounts and also in dry form.

In another object of the present invention is disclosed synergistic herbicidal composition of Pendimethalin and Metribuzin in any of the form selected from wettable powder (WP), Water dispersible granules (WG/WDG) and soil applied granules (SAG) having synergistic effect.

In further object of the present invention is disclosed synergistic herbicidal compositions of Pendimethalin and Metribuzin in any of the form selected from wettable powder (WP), Water dispersible granules (WG/WDG) and soil applied granules (SAG), wherein Pendimethalin and Metribuzin are present in the ratio of 20:1 to 1 :20.

In still further object of the present invention is disclosed synergistic herbicidal compositions of Pendimethalin and Metribuzin in any of the form selected from wettable powder (WP), Water dispersible granules (WG/WDG) and soil applied granules (SAG), which are compatible and stable.

In yet another embodiment of the present invention is disclosed process of preparing synergistic herbicidal composition of Pendimethalin and Metribuzin. In still another embodiment of the present invention is disclosed use of synergistic herbicidal composition of Pendimethalin and Metribuzin in the treatment of weeds of wheat, potato and maize crops infested by Phalaris minor, Avena fatua, Echinochloa colonum, Digitaria sanguinalis, Dactyloctenium aegyptium, Brachiaria mutica, Chenopodium album, Melilotus indica, Medicago sativa, Trianthema monogyna, Digera arvensis, Commelina spp., Rumex spp., and other annual Grassy and broad leaf weeds with synergistic effect.

SUMMARY OF THE INVENTION

The present invention relates to a synergistic herbicidal compositions comprising (a) Pendimethalin (b) Metribuzin present in bioactive amounts with one or more inactive ingredients.

One more aspect of the present invention is to provide a dry composition comprising of bioactive amounts of Pendimethalin and Metribuzin with inactive excipients wherein, the ratio of Pendimethalin to Metribuzin is in the ratio from 20: 1 to 1 : 20. The present invention also relates to process for preparing the synergistic herbicidal compositions comprising of Pendimethalin and Metribuzin in bioactive amounts.

DETAILED DESCRIPTION OF THE INVENTION

Any herbicide, to become widely accepted, must be available to the end user in a form which is easy to handle and apply, it may find limited utility if it cannot be easily handled or effectively applied by the normally used methods.

Herbicides are commonly marketed in a liquid form or dry form which can be used for spraying or dusting or upon addition to water will form dispersions or emulsions for spray application. To obtain an acceptable product, it is necessary to have the herbicide in appropriate particle size. The small particle size is necessary to obtain a relatively stable emulsion or dispersion to permit the spraying of the dispersion without the pesticide settling out. Unless stable emulsions or dispersions are obtained, uniform application of the herbicide cannot be made, even though the settling may not be sufficient to result in plugging of the spray nozzles. It is also essential that the herbicide be readily wettable or miscible with liquids. Another important factor for the acceptability of a dry composition of herbicide is to have the product relatively dust-free. Often the pesticides are irritating chemicals and are very undesirable and hazardous to handle it dusty. In addition, it is also desirable to have a product that is relatively dense which not only minimizes the packaging problems but is more desirable for shipping and hence all these properties can be obtained in its granulated form.

The formulation or composition of the present invention can be used as a pre-emergence and early post-emergence herbicide against weeds of wheat, potato and maize crops infested by Phalaris minor, Avena fatua, Echinochloa colonum, Digitaria sanguinalis, Dactyloctenium aegyptium, Brachiaria mutica, Chenopodium album, Melilotus indica, Medicago sativa, Trianthema monogyna, Digera arvensis, Commelina spp., Rumex spp.,and other annual Grassy and broad leaf weeds with synergistic effect.

The synergistic compositions as per the present invention can be in any of the form selected from wettable powder (WP), Water dispersible granules (WG/WDG) and soil applied granules (SAG) which are in dry form.

The term "composition" and "formulation" as used herein can be used interchangeably. "Bioactive amounts" as mentioned herein means that amount which, when applied treatment of crops, is sufficient to effect such treatment.

The term "synergistic", as used herein, refers the combined action of two or more active agents blended together and administered conjointly that is greater than the sum of their individual effects.

The synergistic composition of the present invention can be any of the below form.

WP - Wettable powders:

A solid pesticide formulation - micronized to powder form and typically applied as suspended particles after dispersion in water.

WG or WDG - Water dispersible granule:

A pesticidal formulation consisting of granules to be applied after disintegration and dispersion in water. Water dispersible granules can be formed by a) agglomeration, b) spray drying, or c) extrusion techniques. It can also be termed as water soluble granules (WSG) or soluble granules (SG).

SAG (Soil applied granules)

Soil-applied granules may be prepared by optionally adsorbing a higher use level active ingredient directly on the clay granule or adsorbing as a diluted solution in an appropriate solvent. These soil applied granules ready to use form which can be directly applied.

The synergistic herbicidal composition of the present invention can be intended for application after disintegration and dispersion in water by conventional spraying equipment or directly to the soils.

The synergistic herbicidal composition of the present invention is formulated in many different ways depending on the physico-chemical properties of the active ingredient and the manufacturing equipment available. This can lead to products of differing appearances and differing particle size ranges.

Pendimethalin and Metribuzin which are active ingredients of the present composition are present in ratio of 20: 1 to 1 : 20 most preferably are present in ratio of 6:1 to 3:1.

The formulations of Pendimethalin and Metribuzin of present this invention is applied in the treatment of weeds in the crops, Wheat (Triticum aestavum), Potato (Solanum tubersoum), Sugarcane (Saccharum officinarum), Maize (Zea mays), Sunflower (Helianthus annuus), Soybean (Glycin max), Peanut (Arachis hypogaea) infested by Phalaris minor, Avena fatua, Echinochloa colonum, Digitaria sanguinalis, Dactyloctenium aegyptium, Brachiaria mutica, Chenopodium album, Melilotus indica, Medicago sativa, Trianthema monogyna, Digera arvensis, Commelina spp., Rumex spp.,and other annual Grassy and broad leaf weeds with synergistic effect.

The formulations of this invention may also be applied in con- junction with other inactive agents commonly employed in the art. Examples of such ingredients include filler, binder, wetting agent, dispersing or suspending agent, stabilizer, carrier, anti-foaming agent and solvent.

Filler are finely divided filler particles, and can include inert mineral fillers. The particle size of the filler will depend upon the ultimate use of the end product. The fillers can be inert compounds that, upon application, break down over time, but provide no other interfering properties, or they can themselves provide a useful function beyond merely breaking down over time to release the pesticidally active material. Fillers as used herein for the present invention can be selected from Mineral earths and clays such as bentonite, kaolin, attapulgite, diatomaceous earth, zeolites, calcium carbonate, talc, china clay, mineral components such as dolomite and limestone, light weight additives such as expanded silica, fly ash, hydrated lime, wheat flour, wood flour, ground wheat straw, cellulose and soy flour, muscovite mica and manufactured materials such as precipitated silicas and silicates, fused sodium potassium, aluminum silicate (heat processed perlite) or organic materials such as coals, lignites and plastics can also be used.

Binders will facilitate to optimize the availability and absorption/adsorption of herbicides contents through soils to the germinating weeds. Binders as used herein can be selected from the group comprising of polyvinyl pyrrolidone, trisiliconealkoxylate, polyvinyl alcohol, alcohol ethoxylate, nonionic block copolymer and the like ormixtures thereof. The amount of the binder in the product must be sufficient to hold the pesticide and to prevent its immediate release and to maintain the efficacy of the product. A wetting agent is a substance that when added to a liquid increases the spreading or penetration power of the liquid by reducing the interfacial tension between the liquid and the surface on which it is spreading. Wetting agents are used for two main functions in agrochemical compositions: during processing and manufacture to increase the rate of wetting of powders in water to make concentrates for soluble liquids or suspension concentrates; and during mixing of a product with water in a spray tank or other vessel to reduce the wetting time of wettable powders and to improve the penetration of water into water-dispersible granules. Examples of wetting agents used in wettable powder, suspension concentrate, and water-dispersible granule compositions include but not limited to sodium lauryl sulphate; sodium dioctylsulphosuccinate; alkyl phenol ethoxylates; and aliphatic alcohol ethoxylates or mixtures thereof.

Dispersing or suspending agent is a substance which adsorbs onto the surface of particles and helps to preserve the state of dispersion of the particles and prevents them from re-aggregating. Dispersing agents are added to agrochemical compositions to facilitate dispersion and suspension during manufacture, and to ensure the particles re-disperse into water in a spray tank. They are widely used in wettable powders, suspension concentrates and water-dispersible granules. Surfactants that are used as dispersants have the ability to adsorb strongly onto a particle surface and provide a charged or steric barrier to re-aggregation of particles. The most commonly used surfactants are anionic, non-ionic, or mixtures of the two types. For wettable powder compositions, the most common dispersants are sodium lignosulphonates. For suspension concentrates, very good adsorption and stabilization are obtained using poly electrolytes, such as sodium naphthalene sulphonate formaldehyde condensates. Tristyrylphenolethoxylate phosphate esters are also used. Nonionics such as alkylarylethylene oxide condensates and EO-PO block copolymers are sometimes combined with anionics as dispersing agents. In recent years, new types of very high molecular weight polymeric surfactants have been developed as dispersing agent. These have very long hydrophobic 'backbones' and a large number of ethylene oxide chains forming the 'teeth' of a 'comb' surfactant. These high molecular weight polymers can give very good long-term stability because the hydrophobic backbones have many anchoring points onto the particle surfaces. Examples of dispersing agents or suspending agents used herein include but not limited to sodium lignosulphonates; sodium naphthalene sulphonate formaldehyde condensates; tristyrylphenolethoxylate phosphate esters; aliphatic alcohol ethoxylates; alky ethoxylates; styrine acrylic polymer, EO-PO block copolymers; and graft copolymers or mixtures thereof.

Stabilizers as used herein are selected from the group comprising of Potassiumsorbate, alcohol ethoxylate, Epichlorohydrin, Epoxidised soybean oil or mixtures thereof.

Carriers as used herein for the present invention can be selected from clays, attapulgite, bentonite, kaolin, sepiolite, kieselguhr, diatomaceous earth, river sand, talc, brick fragments sand, white carbon and vermiculite, corn cobs, walnut shells, rice hulls, and wood, starch natural plant fibers and pumice. Anti-foaming agent as used herein is used for reducing or preventing the formation of foam within the mixture and can be selected from the group comprising of silicone emulsion, perfluoroalkylphosphonic acids, perfluoroalkyl phosphinic acids and perfluoroaliphatic polymeric esters or mixtures thereof. The anti-foaming agent may also facilitate movement of entrapped air out of the mixture. The antifoaming agent may enable the wetting agent and the dispersant, when included, to function properly within the mixture, and may facilitate spraying of the insecticide while reducing the chances of the sprayer becoming clogged with foam or entrained air.

The solvent for the composition of the present invention may include water, water-soluble alcohols and dihydroxy alcohol ethers. The water-soluble alcohol which can be used in the present invention may be lower alcohols or water-soluble macromolecular alcohols. The term "lower alcohol", as used herein, represents an alcohol having 1-4 carbon atoms, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, etc. Macromolecular alcohol is not limited, as long as it may be dissolved in water in a suitable amount range, e.g., polyethylene glycol, sorbitol, glucitol, etc. The examples of suitable dihydroxy alcohol ethers used in the present invention may be dihydroxy alcohol alkyl ethers or dihydroxy alcohol aryl ethers. The examples of dihydroxy alcohol alkyl ether include ethylene glycol methyl ether, diethylene glycol methyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol ethyl ether, propylene glycol ethyl ether, dipropylene glycol ethyl ether, etc. The examples of dihydroxy alcohol aryl ethers include ethylene glycol phenyl ether, diethylene glycol phenyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, and the like. Any of the above mentioned solvent can be used either alone or in combination thereof.

The present invention will now be explained in detail by reference to the following formulation examples, which should not be construed as limiting the scope of the present invention. EXAMPLES

Example 1: WP (Wettable Powder) composition

Lignosulfonic acid,

5.00 5.00 5.00 5.00 5.00 5.00 sodium salt

Sodium

alkylnaphthalenesulfonate 4.00 4.00 4.00 4.00 4.00 4.00

, formaldehyde condensate

Silicone based antifoam 0.50 0.50 0.50 0.50 0.50 0.50

PPT silica 30.00 30.00 30.00 30.00 30.00 30.00

China clay 38.85 38.20 37.80 43.95 43.30 42.90

TOTAL 100.00 100.00 100.00 100.00 100.00 100.00

Procedure:

Example 2: Water Dispersible Granules (WDG) composition

Procedure

Example 3: Soil Applied Granules (SAG) formulation

Procedure:

Example 4: Stability Study of Example 1-3

4.1) Storage stability Study Data of Pendimethalin 15% + Metribuzin 3% WP (Wettable Powder)

Room Temperature storage data

4.2) Storage stability Study of Pendimethalin 15% + Metribuzin 3 % WG (Wettable Granules)

Room Temperature storage data

4.3) Storage stability Study of Pendimethalin 2% + Metribuzin 0.6% SAG (Soil Applied Granules)

Room Temperature Storage Data

Example 5: Field efficacy trials

Wheat is an important cereal crops in India. Weeds are one of the main problems to maintaining wheat productivity and among these, Phalaris minor Retz. (Little seed canary grass) is the most noxious weed of wheat in north-western India. It has developed extensive Isoproturon resistance due to continuous Isoproturon use. Now a day's reduced efficacy of several herbicides including Sulfosulfuron, Clodinafop-Propinyl and Pinoxaden is a main concern for wheat growers. Growers are forced to apply higher doses of Sulfosulfuron, Clodinafop-Propinyl and Pinoxaden because of limited option available to control Phalaris minor. Phalaris minor has developed multiple resistances to above mentioned herbicides.

Looking to the above problem of wheat growers, various dry formulations, like wettable powder (WP), wettable granules (WG) and soil applied granules (SAG) have been developed. These premixes novel formulations were evaluated for its efficacy against different weed flora in major wheat growing area of north India. The field trial was conducted with Randomized Block Design with plot size 10 meter x 5 meter. Wheat crop was raised with standard agronomic practice. The treatments were applied as early post- emergence (10 days after sowing). Periodic observations recorded on species wise weed populations at 30 and 60 days after application of treatments in 5 randomly selected 1 sq m area spot per plot. The treatment details and field observation were presented in table given below.

Table 1 - Sample composition of dry formulations of Pendimethalin + Metribuzin

WP- Wettable Podwer, WG- Wettable Granules, SAG- Soil applied granules, EC- Emulsifiable concentrate, g- gram, PM 1 to 12- Sample code for different formulation of Pendimethalin+Metribuzin Table 2 - Effect of various dry formulations of Pendimethalin+Methribuzin on weed population in wheat crop

Note: DAS- Days after Sowing Grasses comprises of Phalaris minor and Broad leaf weeds comprises of Chenopodium spp., Rumex spp., Melilotus spp., Medicago spp.

Efficacy trail on weed population counts indicates that all the dry formulations (WP, WG and SAG) effectively controls both the grasses and broad leaf weeds in wheat and observed better than all prior art. The formulation ratio of Pendimethalin+Metribuzin varies from 6: 1 to 3: 1 provides excellent control of Phalaris minor and broad leaf weeds also. Table 3 - Impact of dry formulation of Pendimethalin+Metribuzin on Effective tiller count and yield of wheat crop

All the dry formulations of Pendimethalin+Metribuzin gave significantly better grain yield compared to all prior art treatments.

Claims

We claim:

1) A dry composition comprising synergistic bioactive amounts of Pendimethalin and Metribuzin with inactive excipients.

2) The dry composition according to claim 1 , wherein the ratio of Pendimethalin to Metribuzin is in the ratio from 20:1 to 1:20 preferably 6: 1 to 3:1.

3) A dry composition according to claim 1 wherein, inactive excipients comprises of filler, binder, wetting agent, dispersing or suspending agent, stabilizer, carrier, anti-foaming agent and solvent.

4) A dry composition according to claim 3 wherein, filler is selected from Mineral earths and clays such as bentonite, kaolin, attapulgite, diatomaceous earth, zeolites, calcium carbonate, talc, china clay, mineral components such as dolomite and limestone, light weight additives such as expanded silica, fly ash, hydrated lime, wheat flour, wood flour, ground wheat straw, cellulose and soy flour, muscovite mica, precipitated silicas, silicates, fused sodium potassium, aluminum silicate or coals, lignites and plastics.

5) A dry composition according to claim 3 wherein, Binders are selected from the group comprising of polyvinyl pyrrolidone, trisiliconealkoxylate, polyvinyl alcohol, alcohol ethoxylate, nonionic block copolymer.

6) A dry composition according to claim 3 wherein, wetting agent are selected from the group comprising sodium lauryl sulphate; sodium dioctylsulphosuccinate; alkyl phenol ethoxylates; and aliphatic alcohol ethoxylates or mixtures thereof.

7) A dry composition according to claim 3 wherein, Dispersing agent are selected from the group comprising of sodium lignosulphonates, naphthalene sulphonate formaldehyde, Tristyrylphenolethoxylate phosphate esters, alkylarylethylene oxide, sodium lignosulphonates; sodium naphthalene sulphonate formaldehyde condensates; tristyrylphenolethoxylate phosphate esters; aliphatic alcohol ethoxylates; alky ethoxylates; styrine acrylic polymer, EO-PO block copolymers; and graft copolymers or mixtures thereof.

8) A dry composition according to claim 3 wherein, Stabilizer is selected from the group comprising of Potassiumsorbate, alcohol ethoxylate, Epichlorohydrin, Epoxidised soybean oil or mixtures thereof. 9) A dry composition according to claim 3 wherein, Carrier is selected from the group comprising of clays, attapulgite, bentonite, kaolin, sepiolite, kieselguhr, diatomaceous earth, river sand, talc, brick fragments sand, white carbon and vermiculite, corn cobs, walnut shells, rice hulls, and wood, starch natural plant fibers and pumice.

10) A dry composition according to claim 3 wherein, Anti-foaming agent is selected from the group comprising of silicone emulsion, perfluoroalkylphosphonic acids, perfluoroalkylphosphinic acids and perfluoroaliphatic polymeric esters or mixtures thereof.

11) A dry composition according to claim 3 wherein, solvents are selected from the group comprising of water, water-soluble alcohols and dihydroxy alcohol ethers; wherein water-soluble alcohol are methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, polyethylene glycol, sorbitol, glucitol, and dihydroxy alcohol ethers are ethylene glycol methyl ether, diethylene glycol methyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol ethyl ether, propylene glycol ethyl ether, dipropylene glycol ethyl ether, ethylene glycol phenyl ether, diethylene glycol phenyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, solvent can be used either alone or in combination thereof.

12) The dry composition as claimed in claim 1 or 2 wherein the composition may be selected from Wettable powders (WP), Water dispersible granules (WG or WDG) and Soil Applied Granules (SAG).

13) The dry composition as claimed in claim 1, wherein the said composition is used for control of Weeds in the crops, Wheat (Triticum aestavum), Potato (Solanum tubersoum), Sugarcane (Saccharum officinarum), Maize (Zea mays), Sunflower (Helianthus annuus), Soybean (Glycin max), Peanut (Arachis hypogaea)

14) The dry composition as claimed in claim 1 , wherein plant disease controlling effect, comprises Phalaris minor, Avena fatua, Echinochloa colonum, Digitaria sanguinalis, Dactyloctenium aegyptium, Brachiaria mutica, Chenopodium album, Melilotus indica, Medicago sativa, Trianthema monogyna, Digera arvensis, Commelina spp., Rumex spp.

15) The dry composition of Pendimethalin and Metribuzin as claimed in any of the preceding claims and exemplified with working examples as disclosed.