WO2017107580A1

WO2017107580A1 - Herbicidal composition and use thereof

Info

Publication number: WO2017107580A1
Application number: PCT/CN2016/098774
Authority: WO
Inventors: James Timothy BRISTOW
Original assignee: Rotam Agrochem International Company Limited
Priority date: 2015-12-23
Filing date: 2016-09-13
Publication date: 2017-06-29
Also published as: GB201522829D0; GB2545732B; GB2545732A

Abstract

A herbicidal composition is provided, the composition comprising (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin in a herbicidally effective amount. A method of controlling unwanted plant growth comprises applying to the plants or a locus thereof a herbicidally amount of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin.

Description

HERBICIDAL COMPOSITION AND USE THEREOF

Cross Reference of related application

The present application claims the priority of UK Patent Application No. GB1522829.9, filed on December 23, 2015, the contents of which are incorporated herein by reference in its entirety.

The present invention relates to a herbicidal composition comprising a synergistic mixture of a plurality of active ingredients. The invention also relates to a method of controlling the growth of undesirable plants using a combination of the aforementioned active ingredients, particularly in crops, including using the aforementioned composition.

The protection of crops from undesirable plants, which inhibits crop growth, is a constantly recurring problem in agriculture. To solve this problem, researchers are trying to produce an extensive variety of chemicals and chemical formulations effective in the control of such undesirable plant growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use.

Mesosulfuron, iodosulfuron and metribuzin are compounds known to be herbicidally active and to be of use in the control of unwanted plant growth, for example in the protection of a range of crops.

Mesosulfuron and iodosulfuron are branched chain amino acid synthesis (ALS) inhibitors. Both compounds are sulfonylureas and act by inhibiting biosynthesis of the essential amino acids valine and isoleucine, with the effect of stopping cell division of the plant and plant growth.

Metribuzin is a triazinone and acts as an inhibitor of photosynthesis. Metribuzin can be absorbed by the roots and leaves of plants to which it is applied and is then translocated in the xylem. Metribuzin is known to be useful in the control of grasses and broad-leaved weeds.

It has now surprisingly been found that mesosulfuron, iodosulfuron and metribuzin display a synergistic effect in the control of plant growth when applied in combination, for example in a composition comprising all three compounds or when applied separately to a locus to be treated.

The synergistic effects of the combination of mesosulfuron, iodosulfuron and metribuzin forming the basis of the present invention can provide one or more of a number of advantages over the use of each component (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin alone. In particular, the rates of application of each component can be markedly reduced, when the three compounds are used in combination, while maintaining a high level of herbicidal efficacy. More especially, the use of the combination of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin has the potential to control weed species at a low application rate, in particular at a rate of application at which the individual components alone are ineffective. A treatment using (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin can exhibit a considerably broader weed spectrum than the components when used alone. The use of a composition comprising the three aforementioned active components also has a speed of action which is faster than that which would have been predicted from the speed of each component used individually.

In a first aspect, the present invention provides a composition comprising a herbicidally effective amount of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin.

“Herbicide” as used herein, refers to a compound that controls the growth of plants.

“Herbicidally effective amount” as used herein, refers to the quantity of such a compound or combination of such compounds that is capable of producing a controlling effect on the growth of plants.

The “controlling effects” include all deviations from the natural development of the target plants, for example killing, retardation of one or more aspects of the development and growth of the plant, leaf burn, albinism, dwarfing and the like.

The term “plants” refers to all physical parts of a plant, including shoots, leaves, needles, stalks, stems, fruit bodies, fruits, seeds, roots, tubers and rhizomes.

If the abbreviation of the "common name" of the herbicides is used in the present specification, it is to be understood as including all conventional derivatives, such as the esters and salts, and isomers, in particular the optical isomers, and all commercially available form or forms of the compound. If the "common name" refers to an ester or salt, this also includes all of the other usual derivatives, such as other esters and salts, the free acids, neutral compounds and isomers, in particular optical isomers, and all commercially available form or forms. The chemical compound names stated refer at least to one of the compounds encompassed by the "common name" , frequently to a preferred compound. In the case of sulfonamides, such as sulfonylureas, salts also include those which are formed by exchanging a hydrogen atom on the sulfonamide group by a cation.

The above mentioned compound (A) encompasses all stereoisomers and their mixtures, in particular also racemic mixtures and, if enantiomers are possible, the particular enantiomer which has a biological action. Examples of compound (A) and its salts are 2- [(4, 6-dimethoxypyrimidin-2-ylcarbamoyl) sulfamoyl] -α-methanesulfonamido-p-toluic acid (mesosulfuron) and its ester or a salt, such as the lower alkyl esters, in particular methyl 2- [(4, 6-dimethoxypyrimidin-2-ylcarbamoyl) sulfamoyl] -α- (methanesulfon amido) -p-toluate (mesosulfuron-methyl) . Preferably, compound (A) is mesosulfuron-methyl.

The above mentioned compound (B) encompasses all stereoisomers and their mixtures, in particular also racemic mixtures, and, in as far as enantiomers are possible, all of the biologically active enantiomers. Examples of compound (B) include its esters, such as the lower alkyl esters, in particular 3- (4-methoxy-6-methyl-1, 3, 5-triazin-2-yl) -1-(2-methoxycarbonyl-5-iodophenylsulfonyl) urea (iodosulfuron-methyl) and its salts, such as the alkali metal salts, in particular the sodium salt (iodosulfuron-methyl-sodium) . Preferably, (B) is iodosulfuron-methyl-sodium. Iodosulfuron-methyl-ester is known in the art, for example from WO 92/13845.

The above mentioned compound (C) encompasses all stereoisomers and their mixtures, in particular also racemic mixtures, and, in as far as enantiomers are possible, all of the biologically active enantiomers, and their salts. Preferably, (C) is metribuzin.

In a further aspect, the present invention provides a method of controlling undesirable plant growth comprising applying to the plants or to the locus thereof herbicidally effective amounts of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin.

In one preferred embodiment of the method, the compounds (A) , (B) and (C) are applied by way of a composition of the first aspect of the present invention.

In a still further aspect, the present invention provides the use of a combination of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin in the control of plant growth, in particular undesirable plant growth.

The composition and methods of the present invention are useful in controlling undesirable plants in a range of crops, including cereals, vegetables, leguminous plants. The control of undesirable plants in such crops may be achieved by applying to the plants or to locus of the plants (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin in suitable amounts. The active compounds may be applied to the locus together or separately. The control may comprise applying to the plants or the locus thereof a herbicidally effective amount of the herbicidal composition of the present invention.

The species spectrums of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin, that is, the monocotyledonous and dicotyledonous undesirable plants that the respective compounds control, are broad and highly complementary. The active ingredients also act efficiently on perennial weeds which produce shoots from rhizomes, rootstocks or other perennial organs and which are difficult to control. The compounds may be applied to the crops or their locus before sowing, pre-emergence or post-emergence. Post-emergence application or pre-emergence application, especially early post-sowing pre-emergence application, are preferred.

Examples of plants generally considered to be undesirable weeds that may be controlled using the present invention include:

Abutilon spp., Agropyron spp., Alopecurus spp., Amaranthus spp., Apera spp., Artemisia spp., Avena spp., Brachiaria spp., Bromus spp., Cenchus spp., Chenopodium spp., Chrysanthemum spp., Cirsium spp., Convolvulus spp., Cynodon spp., Cyperus spp., Digitaria spp., Echinochloa spp., Equinochloa spp., Eragrostis spp., Erichloa spp., Galium spp., Hordeum spp., Imperata spp., Ipomoea spp., Kochia spp., Lamium spp., Leptochlooa spp., Lolium spp., Matricaria spp., Oryza spp., Panicum spp., Phalaris spp., Pharbitis spp., Poa spp., Polygonum spp., Rumex spp., Setaria spp., Sida spp., Sinapis spp., Solanum spp., Sorghum spp., Stellaria spp., Trifolium spp., Tritcum spp., Veronica spp., Viola spp., and Xanthium spp.

Preferred target plants to be controlled include: Bromus spp., Cenchus spp., Cyperus spp., Digitaria spp., Echinochloa spp., Eragrostis spp., Erichloa spp., Hordeum spp., Ipomoea spp., Leptochlooa spp., Lolium spp., Oryza spp., Panicum spp., Rumex spp., Solanum spp., Sorghum spp., Trifolium spp., and Tritcum spp.

The composition and methods of the present invention have been found to be particularly effective in the control of annual ryegrass (Lolium multiflorum) , sub clover (Trifolium subterraneum) , barley grass (Hordeum spp. ) , brome grass (Bromus diandrus) , brome grass (Bromus rigidus) , dock (Rumex spp. ) , summer grasses (Digitaria spp. ) , black nightshade (Solanum nigrum) , ivyleaf morningglory (Ipomoea hederacea) , pitted morningglory (Ipomoea lacunosa) , tall morningglory (Ipomoea purpurea) , cupgrass (Erichloa gracllis) , yellow nutsedge (Cyperus esculentus) , panicum fall (Panicum dichotomiflorum) , Texas panicum (Panicum texanum) , red rice (Oryza sativa) , sandbur (Cenchus spp. ) , shattercane (Sorghum bicolor) , volunteer sorghum (Sorghum spps) , sprangletop (Leptochlooa spp. ) , stinkgrass (Eragrostis spp. ) , volunteer wheat (Tritcum spp. ) , witchgrass (Panicum capillare) , and panicum grass (Echinochloa crus galli) .

The combination of herbicides of the present invention exhibits synergistic effects. The synergistic effects are observed when the herbicides (A) , (B) and (C) are applied together to a plant and/or a locus. The compounds may be applied to the plant or locus at the same time. Alternatively, the compounds may be applied to the target plants and/or locus over a period of time.

The individual herbicides (A) , (B) and (C) or the herbicide combination may be applied in a single treatment or in several treatments (sequential application) , for example one or more pre-emergence applications, followed by one or more post-emergence applications or one or more early post-emergence applications, and/or followed by one or more applications at medium or late post-emergence. Each application may employ one, two or all of the herbicides (A) , (B) and (C) .

Preferably, the compounds (A) , (B) and (C) are applied at the same time, that is simultaneously, or in rapid succession, that is nearly simultaneous application.

The total application rate of compounds (A) and (B) can vary within a wide range, for example from 1 to 500g per hectare (g/ha) . Preferably, the application rate ranges from 2 to 400 g/ha, more preferably from 3 to 300 g/ha, still more preferably from 5 to 200 g/ha. The application rate of compounds (A) and (B) may be the same or different.

The application rate of (C) can vary within a wide range, for example from 10 to 3000 g/ha. Preferably, the application rate ranges from 15 to 2500 g/ha, more preferably from 20 to 2000 g/ha.

Compounds (A) and (B) are preferably applied in a weight ratio of (A) to (B) of from 100: 1 to 1: 100, more preferably from 50: 1 to 1: 50, still more preferably from 25: 1 to 1: 25, more preferably still from 10: 1 to 1: 10, more particularly from 5: 1 to 1: 5, still more particularly from 5: 1 to 1: 1, with weight ratios of 5: 1, 4: 1, 3: 1, 2: 1, and 1: 1, being preferred.

The weight ratio of the total of compounds (A) and (B) to compound (C) as applied is preferably from 100: 1 to 1: 300, more preferably from 50: 1 to 1: 200, still more preferably from 25: 1 to 1: 150, more preferably from 10: 1 to 1: 100, more particularly from 5: 1 to 1: 100, still more particularly 1: 100, 1: 75, 1: 50, 1: 25, 1: 20, 1: 15, and 1: 10.

The active synergistic components may be present in the composition of the present invention in a wide range of amounts. In preferred embodiments, the total amount of (A) , (B) and (C) is from 5％to 95％by weight of the composition. In some preferred embodiments of this invention, the composition comprises, by weight, from 1％to 70％of (A) , from 1％to 70％of (B) and from 10％to 80％of (C) . In some preferred embodiments of this invention, the composition comprises, by weight, from 1％to 50％of (A) , from 1％to 50％of (B) and from 15％to 75％of (C) .

The compositions of this invention can be formulated in conventional manner, for example by mixing (A) , (B) and (C) with appropriate auxiliaries. Suitable auxiliaries will depend upon such factors as the type of formulation and the manner of the end use of the formulation, and will be known to the person skilled in the art.

In particular, the composition may further comprise one or more auxiliaries selected from extenders, carriers, solvents, surfactants, stabilizers, anti-foaming agents, anti-freezing agents, preservatives, antioxidants, colorants, thickeners, solid adherents, fillers, wetting agents, dispersing agents, lubricants, anticaking agents and diluents. Such auxiliaries are known in the art and are commercially available. Their use in the formulation of the compositions of the present invention will be apparent to the person skilled in the art.

The active ingredients employed in the present invention can be formulated as water-soluble concentrates (SL) , emulsifiable concentrates (EC) , oil in water emulsions (EW) , micro-emulsions (ME) , suspension concentrates (SC) , oil-based suspension concentrates (OD) , flowable suspensions (FS) , water-dispersible granules (WDG) , water-soluble granules (SG) , wettable powders (WP) , water soluble powders (SP) , granules (GR) , encapsulated granules (CG) , fine granules (FG) , macrogranules (GG) , aqueous suspo-emulsions (SE) , capsule suspensions (CS) and microgranules (MG) . Preferred formulations are suspension concentrates (SC) , water-soluble granules (SG) , water-dispersible granules (WDG) , wettable powders (WP) and oil-based suspension concentrates (OD) . Preferably, the active ingredients are formulated as suspension concentrates (SC) , water-dispersible granules (WDG) , water-soluble granules (SG) , or wettable powders (WP) .

Each of the aforementioned formulations may comprise one, two or all three of the compounds (A) , (B) and (C) , preferably all three compounds.

The composition may comprise one or more inert fillers. Such inert fillers are known in the art and available commercially. Suitable fillers include, for example, natural ground minerals, such as kaolins, aluminas, talc, chalk, quartz, attapulgite, montmorillonite, and diatomaceous earth, or synthetic ground minerals, such as highly dispersed silicic acid, aluminum oxide, silicates, and calcium phosphates and calcium hydrogen phosphates. Suitable inert fillers for granules include, for example, crushed and fractionated natural minerals, such as calcite, marble, pumice, sepiolite, and dolomite, or synthetic granules of inorganic and organic ground materials, as well as granules of organic material, such as sawdust, coconut husks, corn cobs, and tobacco stalks.

The composition may optionally include one or more surfactants which are preferably non-ionic, cationic and/or anionic in nature and surfactant mixtures which have good emulsifying, dispersing and wetting properties, depending upon the active compound/compounds being formulated. Suitable surfactants are known in the art and are commercially available.

Suitable anionic surfactants can be both so-called water-soluble soaps and water-soluble synthetic surface-active compounds. Soaps which may be used include the alkali metal, alkaline earth metal or substituted or unsubstituted ammonium salts of higher fatty acid (C₁₀ to C₂₂) , for example the sodium or potassium salt of oleic or stearic acid, or of natural fatty acid mixtures.

The surfactant may comprise an emulsifier, dispersant or wetting agent of an ionic or nonionic type. Examples of such agents include salts of polyacrylic acids, salts of lignosulphonic acid, salts of phenylsulphonic or naphthalenesulphonic acids, polycondensates of ethylene oxide with fatty alcohols or with fatty acids or with fatty amines, substituted phenols, especially alkylphenols, sulphosuccinic ester salts, taurine derivatives, especially alkyltaurates, and phosphoric esters of polyethoxylated phenols or alcohols.

The presence of at least one surfactant is generally required when the active compound and/or the inert carrier and/or auxiliary/adjuvant are insoluble in water and the vehicle for the final application of the composition is water.

The composition may optionally further comprise one or more polymeric stabilizers. Suitable polymeric stabilizers that may be used in the present invention include, but are not limited to, polypropylene, polyisobutylene, polyisoprene, copolymers of monoolefins and diolefins, polyacrylates, polystyrene, polyvinyl acetate, polyurethanes or polyamides. Suitable stabilizers are known in the art and are commercially available.

The surfactants and polymeric stabilizers mentioned above are generally believed to impart stability to the composition, in turn allowing the composition to be formulated, stored, transported and applied.

Suitable anti-foaming agents for use in the compositions include all substances which can normally be used for this purpose in agrochemical compositions. Suitable anti-foaming agents are known in the art and are available commercially. Particularly preferred anti-foaming agents are mixtures of polydimethylsiloxanes and perfluroalkylphosphonic acids, such as the silicone anti-foaming agents available from GE or Compton.

Suitable solvents for use in the compositions may be selected from all customary organic solvents which thoroughly dissolve one or more of the active compounds employed. Again, suitable organic solvents for compounds (A) , (B) and (C) are known in the art. The following may be mentioned as being preferred: N-methyl pyrrolidone, N-octyl pyrrolidone, cyclohexyl-1-pyrrolidone； and a mixture of paraffinic, isoparaffinic, cycloparaffinic and aromatic hydrocarbons (available commercially as SOLVESSO^TM200) . Suitable solvents are commercially available.

Suitable preservatives include all substances which can normally be used for this purpose in agrochemical compositions of this type and again are well known in the art. Suitable examples that may be mentioned include

(from Bayer AG) and

(from Bayer AG) .

The compositions may comprise an antioxidant. Suitable antioxidants are all substances which can normally be used for this purpose in agrochemical compositions, as is known in the art. Preference is given to butylated hydroxytoluene.

Suitable thickeners for use in the compositions include all substances which can normally be used for this purpose in agrochemical compositions. Examples include xanthan gum, PVOH, cellulose and its derivatives, clay hydrated silicates, magnesium aluminum silicates or a mixture thereof. Again, such thickeners are known in the art and available commercially.

The compositions may further comprise one or more solid adherents. Such adherents are known in the art and available commercially. They include organic adhesives, including tackifiers, such as celluloses or substituted celluloses, natural and synthetic polymers in the form of powders, granules, or lattices, and inorganic adhesives such as gypsum, silica, or cement.

In the method and use of the present invention, the combination of the active ingredients (A) , (B) and (C) can be applied to the locus where control is desired, such as to the leaves of plants and/or the surrounding soil, by any convenient method. The “locus” refers to the place where the plants are growing, the place where the plant propagation materials of the plants being protected are sown or the place where the plant propagation materials of the plants being protected will be sown.

For use of compounds (A) , (B) and (C) or their salts in plant crops, it is expedient, depending on the plant crop, to apply a safener from certain application rates upwards, in order to reduce or to avoid damage to the crop plants. Examples of suitable safeners are those which have a safener action in combination with sulfonylurea herbicides. Suitable safeners are disclosed in WO 96/14747 and the literature cited therein.

The compositions and methods of the present invention are suitable for controlling harmful plants in crops of a range of valuable plants, for example in economically important crops such as cereals (wheat, barley, rye, oats, maize, rice, sorghum, triticale and related crops) ； fruit, such as pomes, stone fruit and soft fruit, such as apples, grapes, pears, plums, peaches, almonds, pistachio, cherries, and berries, for example strawberries, raspberries and blackberries, bell pepper, red pepper； leguminous plants (beans, lentils, peas, soybeans) ； oil plants (rape, mustard, sunflowers) ； cucurbitaceae (marrows, cucumbers, melons) ； fibre plants (cotton, flax, hemp, jute) ； citrus, such as calamondin, citrus citron, citrus hybrids (includes chironja, tangelo, tangor) , grapefruit, kumquat, lemon, lime, mandarin (tangerine) , sour orange, sweet orange, pummelo, and satsuma mandarin； vegetables (spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, paprika) ； coffee； sugarcane； as well as ornamentals (flowers, such as rose, shrubs, broad-leaved trees and evergreens, such as conifers) .

The present invention is particularly advantageous in the protection of cereals, vegetables, leguminous plants and sugarcane, more preferably maize, rice, wheat, barley, durum, triticale, oat, asparagus, potato, tomato, soybean, peas and sugarcane.

Also encompassed by the invention are those herbicide combinations which additionally contain one or more further agrochemical active compounds, such as herbicides, insecticides, nematicides, fungicides, safeners, growth factor enhancers and fertilizers, in addition to the components (A) , (B) and (C) .

Suitable crops for treatment using the composition and method of the present invention include those which are tolerant to (A) , (B) and/or (C) . The tolerance can be a natural tolerance produced by selective breeding or can be artificially introduced by genetic modification of the crop. In this respect, tolerance means a low susceptibility to damage caused by a particular herbicide.

The active ingredients and compositions employed in the practice of the present invention can be applied in a variety of ways known to those skilled in the art, at various concentrations. The method and compositions of the present invention are useful in controlling the growth of undesirable plants by pre-planting, pre-emergence and/or post-emergence application to the plants and/or their locus where control is desired. The active ingredients (A) , (B) and (C) may be applied to the plants and/or their locus by conventional methods, including coating, spraying, sprinkling, dipping, soaking, injection, irrigation, and the like.

Embodiments of the present invention will now be described, for illustrative purposes only, by way of the following examples.

Percentages are percentage by weight, unless otherwise indicated.

EXAMPLES

Formulation Examples

Preparation of Wettable Powder (WP)

A wettable powder (WP) was prepared from the following components by mixing and milling under compressed air.

Preparation of Water-Dispersible Granules (WDG)

A water-dispersible granule (WDG) formulation was prepared by mixing and milling the following components under the action of compressed air. The resulting mixture was wetted to form a paste, extruded and dried to obtain the granules.

Preparation of Suspension Concentrate (SC)

An aqueous suspension concentrate (SC) was prepared by mixing the following components.

Preparation of Water-Soluble Granules (SG)

Water-soluble granules (SG) were prepared by mixing and milling the following components under compressed air, then wetting, extruding and drying to obtain the granules.

The procedures described above were used to prepare a range of formulations, designated as Examples 1 to 17, the details of which are summarized in Table A below.

Table A

		(A)	(B)	(C)
Example	Formulation Type	Mesosulfuron (％)	Iodosulfuron (％)	Metribuzin (％)
1	SC	4	0	0
2	WDG	0	4	0
3	WDG	0	0	75
4	WP	0	1.0	75.0
5	SC	0	1.0	37.5
6	WP	1.0	0	75.0
7	SC	1.0	0	37.5
8	SC	0.2	1.0	50.0
9	SC	1.0	0.2	45.0
10	SC	1.0	1.0	40.0
11	WP	0.5	1.0	75.0
12	SG	2.0	1.0	37.5
13	WDG	0.5	2.0	60.0
14	WP	0.5	0.1	70.0
15	WDG	4.0	0.4	50.0
16	WP	1.0	0.5	75.0
17	SC	1.0	4.0	37.5

Biological Examples

The formulations of Examples 1 to 17 were tested for their biological activity, as follows:

Biological Example 1

Barley, wheat, sugarcane and oat plants were sown side by side in beds in the field. The different types of weeds present in the beds and their relative densities were recorded, the details of which are set out in Table 1 below.

The formulations of Examples 1 to 17 were applied 50 days after planting. After spraying the plants, the beds were maintained for about 2 weeks.

Two weeks after application, the beds were examined to determine the efficiency of the treatment in controlling each weed species. The efficiency indicated is the percentage of the weed species killed by the treatment, with an efficiency of 0％indicating no reduction in the weed population and 100％indicating all the weed plants being killed as a result of the treatment. The results are set forth below in Table 2 below.

Table 1

Type of weed	Relative density (％)
Annual ryegrass (Lolium multiflorum)	25
Brome grass (Bromus rigidus)	5
Summer grasses (Digitaria spp. )	10
Black nightshade (Solanum nigrum)	10
Ivyleaf morningglory (Ipomoea hederacea)	25
Pitted morningglory (Ipomoea lacunosa)	10
Volunteer sorghum (Sorghum spps. )	15

The data summarized in Table 2 demonstrate that the combination of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin exhibits significant synergy in the control of weeds.

Biological Example 2

Maize, soybean, peas and triticale plants were sown side by side in beds in the field. The different types of weeds present in the beds and their relative densities were recorded and are listed in Table 3 below.

Two weeks after application, the beds were examined to determine the efficiency of the treatment, as in Biological Example 1. The results are set forth below in Table 4 below.

Table 3

Type of weed	Relative density (％)
Sub clover (Trifolium subterraneum)	15
Cupgrass (Erichloa gracllis)	20
Red rice (Oryza sativa)	15
Shattercane (Sorghum bicolor)	15
Panicum grass (Echinochloa crus galli)	35

The data summarized in Table 4 demonstrate that the combination of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin exhibits significant synergy in the control of weeds.

Biological Example 3

Durum, asparagus, potato, tomato plants were sown side by side in beds in the field. The different types of weeds present in the beds and their relative densities were recorded and are listed in Table 5 below.

Two weeks after application, the beds were examined to determine the efficiency of the treatment, as in Biological Example 1. The results are set forth below in Table 6 below.

Table 5

Type of weed	Relative density (％)
Brome grass (Bromus diandrus )	10
Dock (Rumex spp. )	5
Tall morningglory (Ipomoea purpurea)	15
Yellow nutsedge (Cyperus esculentus)	15
Texas panicum (Panicum texanum)	10
Sandbur (Cenchus spp. )	25
Sprangletop (Leptochlooa spp. )	20

The data summarized in Table 6 demonstrate that the combination of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin exhibits significant synergy in the control of weeds.

Biological Example 4

Rice plants were sown side by side in beds in the field. The different types of weeds present in the beds and their relative densities were recorded and are listed in Table 7 below.

The formulations of Examples 1 to 17 were applied to the beds 50 days after planting. After spraying the plants, the beds were maintained for about 2 weeks.

Two weeks after application, the beds were examined to determine the efficiency of the treatment, as in Biological Example 1. The results are set forth below in Table 8 below.

Table 7

Type of weed	Relative density (％)
Stinkgrass (Eragrostis spp. )	15
Volunteer wheat (Tritcum spp. )	25
Witchgrass (Panicum capillare)	25
Barley grass (Hordeum spp. )	10
Fall panicum (Panicum dichotomiflorum)	25

The data summarized in Table 8 demonstrate that the combination of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin exhibits significant synergy in the control of weeds.

Claims

A herbicidal composition comprising (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin in a herbicidally effective amount.
The herbicidal composition according to claim 1, wherein (A) is selected from 2- [ (4, 6-dimethoxypyrimidin-2-ylcarbamoyl) sulfamoyl] -α-methanesulfonamido-p-toluic acid (mesosulfuron) , its esters, its salts, and mixtures thereof.
The herbicidal composition according to claim 2, wherein (A) comprises mesosulfuron-methyl.
The herbicidal composition according to any preceding claim, wherein (B) is selected from iodosulfuron, its esters, its salts, and mixtures thereof.
The herbicidal composition according to claim 4, wherein (B) is selected from 3- (4-methoxy-6-methyl-1, 3, 5-triazin-2-yl) -1- (2-methoxycarbonyl-5-iodophenylsulfonyl) urea (iodosulfuron-methyl) and its salts.
The herbicidal composition according to claim 5, wherein (B) comprises an alkali metal salt of iodosulfuron-methyl.
The herbicidal composition according to claim 6, wherein (B) comprises iodosulfuron-methyl-sodium.
The composition according to any preceding claim, wherein the weight ratio of (A) to (B) is from 100: 1 to 1: 100.
The composition according to claim 8, wherein the weight ratio of (A) to (B) is from 10: 1 to 1: 10.
The composition according to claim 9, wherein the weight ratio of (A) to (B) is from 5: 1 to 1: 5.
The composition according to any preceding claim, wherein the weight ratio of (A) + (B) to (C) is from 25: 1 to 1: 150.
The composition according to claim 11, wherein the weight ratio of (A) + (B) to (C) is from 10: 1 to 1: 100.
The composition according to claim 12, wherein the weight ratio of (A) + (B) to (C) is from 5: 1 to 1: 100.
The composition according to any preceding claim, comprising components (A) , (B) and (C) in an amount of from 5％ to 95％ by weight of the composition.
The composition according to claim 14, comprising from 1％ to 70％ by weight of (A) , from 1％ to 70％ by weight of (B) and from 10％ to 80％ by weight of (C) .
The composition according to claim 15, comprising from 1％ to 50％ by weight of (A) , from 1％ to 50％ by weight of (B) and from 15％ to 75％ by weight of (C) .
The composition according to any preceding claim, further comprising one or more auxiliaries selected from extenders, carriers, solvents, surfactants, stabilizers, anti-foaming agents, anti-freezing agents, preservatives, antioxidants, colorants, thickeners, solid adherents, fillers, wetting agents, dispersing agents, lubricants, anticaking agents, emulsifier, diluents and fillers.
The composition according to any preceding claim, wherein the composition is formulated as a suspension concentrate (SC) , water-dispersible granules (WDG) , water-soluble granules (SG) , or a wettable powder (WP) .
Use of (A) mesosulfuron, (B) iodosulfuron, and (C) metribuzin in a herbicidally effective amount for controlling undesired plant growth.
The use according to claim 19, wherein components (A) , (B) and (C) are employed by way of a composition according to any of claims 1 to 18.
The use according to either of claims 19 or 20, wherein the components (A) , (B) and (C) are applied to a locus comprising one or more crops selected from cereals, fruit, leguminous plants, oil plants, cucurbitaceae, fibre plants, citrus, citrus hybrids, vegetables, coffee, sugarcane, and ornamentals.
The use according to any of claims 19 to 21, wherein the undesired plant being controlled is one or more of Abutilon spp., Agropyron spp., Alopecurus spp., Amaranthus spp., Apera app., Artemisia spp., Avena spp., Brachiaria spp., Bromus spp., Cenchus spp., Chenopodium spp., Chrysanthemum spp., Cirsium spp., Convolvulus spp., Cynodon spp., Cyperus spp., Digitaria spp., Echinochloa spp., Equinochloa spp., Eragrostis spp., Erichloa spp., Galium spp., Hordeum spp., Imperata spp., Ipomoea spp., Kochia spp., Lamium spp., Leptochlooa spp., Lolium spp., Matricaria spp., Oryza spp., Panicum spp., Phalaris spp., Pharbitis spp., Poa spp., Polygonum spp., Rumex spp., Setaria spp., Sida spp., Sinapis spp., Solanum spp., Sorghum spp., Stellaria spp., Trifolium spp., Tritcum spp., Veronica spp., Viola spp., Xanthium spp.
A method for controlling unwanted plant growth, comprising applying to the plants or a locus thereof a herbicidally amount of (A) mesosulfuron, (B) iodosulfuron and (C) metribuzin.
The method according to claim 23, wherein the locus is selected from the place where the plants are growing, the place where the plant propagation materials of the plants being protected are sown or the place where the plant propagation materials of the plants being protected will be sown.
The method according to either of claims 23 or 24, wherein the components (A) , (B) and (C) are applied sequentially and/or simultaneously.
The method according to any of claims 23 to 25, wherein one or more of the components (A) , (B) and (C) are applied at one or more of the following stages in the development of the plants:

(a) pre-emergence,

(b) post-emergence or early post-emergence,

(c) medium or late post-emergence.
The method according to any of claims 23 to 26, wherein the unwanted plant being controlled is one or more of Abutilon spp., Agropyron spp., Alopecurus spp., Amaranthus spp., Apera app., Artemisia spp., Avena spp., Brachiaria spp., Bromus spp., Cenchus spp., Chenopodium spp., Chrysanthemum spp., Cirsium spp., Convolvulus spp., Cynodon spp., Cyperus spp., Digitaria spp., Echinochloa spp., Equinochloa spp., Eragrostis spp., Erichloa spp., Galium spp., Hordeum spp., Imperata spp., Ipomoea spp., Kochia spp., Lamium spp., Leptochlooa spp., Lolium spp., Matricaria spp., Oryza spp., Panicum spp., Phalaris spp., Pharbitis spp., Poa spp., Polygonum spp., Rumex spp., Setaria spp., Sida spp., Sinapis spp., Solanum spp., Sorghum spp., Stellaria spp., Trifolium spp., Tritcum spp., Veronica spp., Viola spp., Xanthium spp.
The method according to any of claims 23 to 27, wherein the total application rate of components (A) and (B) is from 5 to 200 g/ha.
The method according to any of claims 23 to 28, wherein the application rate of component (C) is from 20 to 2000 g/ha.
The method according to any of claims 23 to 29, wherein the weight ratio of (A) to (B) is from 100: 1 to 1: 100.
The method according to claim 30, wherein the weight ratio of (A) to (B) is from 10: 1 to 1: 10.
The method according to claim 31, wherein the weight ratio of (A) to (B) is from 5: 1 to 1: 5.
The method according to any of claims 23 to 32, wherein the weight ratio of (A) + (B) to (C) is from about 25: 1 to about 1: 150.
The method according to claim 33, wherein the weight ratio of (A) + (B) to (C) is from 10: 1 to 1: 100.
The method according to claim 34, wherein the weight ratio of (A) + (B) to (C) is from 5: 1 to 1: 100.
A herbicidal composition substantially as hereinbefore described.
A method for controlling undesirable plant growth substantially as hereinbefore described.
A use of (A) mesosulfuron, (B) iodosulfuron, and (C) metribuzin substantially as hereinbefore described.