DESC:FIELD OF THE INVENTION

The present invention relates to a synergistic herbicidal composition comprising a mixture of an isoxazolidinone herbicide, a triazinone herbicide, and a diphenyl ether herbicide. Particularly the present invention relates to a synergistic herbicidal composition comprising of bixlozone, metribuzin and oxyfluorfen in effective amounts along with suitable agrochemical additives and its method thereof.

BACKGROUND OF THE INVENTION

Enhancement of agricultural produce requires the protection of the crops and its produce from pest damage and unwanted vegetation. Various chemicals and their formulations have been developed and are in use currently for the effective management of the same.
Herbicides are also used extensively away from the farm, in areas such as industrial sites, roadsides, ditch banks, irrigation canals, fence lines, recreational areas, lawns, railroad embankments, and power line rights-of-way. Herbicides remove undesirable plants that might cause damage, present fire hazards, or impede work crews. They also reduce costs of labour for mowing. These are classed as selective when they are used to kill weeds without harming the crop and as nonselective when the purpose is to kill all vegetation. Both selective and nonselective materials can be applied to weed foliage or to soil containing weed seeds and seedlings, depending on the mode of action, and intended use pattern.
Another classification of herbicides includes either contact or translocated categories. Contact herbicides kill the plant parts onto whose surfaces the chemical is applied and are most effective against annuals, those weeds that germinate from seeds and grow to maturity each year. Complete coverage is essential in weed control with contact materials. Translocated herbicides are absorbed either by roots or above-ground parts of plants and are circulated within the plant system to distant tissues. Translocated herbicides may be effective against all weed types; however, their greatest advantage is in the control of established perennials, those weeds that continue their growth from year to year. Uniform application is a key requirement in achieving good weed control with translocated herbicides.

Herbicides are also classed according to timing of application, i.e., growth stage of crop or weed development. What constitutes the best timing varies by chemical class of the material and its persistence, the crop, and its tolerance to the herbicide, weed species, cultural practices, climate, and soil type and condition. The three primary categories of application timing are preplanting, preemergence, and post emergence.
Preplanting applications for control of annual weeds are made to an area before the crop is planted, within a few days or weeks of planting and often includes a step to incorporate the herbicide in the soil. In recent years such preplant uses have included making fall applications of herbicides to suppress early weed growth the next spring before corn is planted. Preemergence applications are completed prior to emergence of the crop or weeds, depending on definition, after planting. Postemergence applications are made after the crop or weed emerges from the soil.
Herbicide application based on the area covered involves four categories: band, broadcast, spot treatments, and directed spraying. A band application treats a continuous strip, as along or in a crop row. Broadcast application covers the entire area, including the crops. Spot treatments are confined to small areas of weeds. Directed sprays are applied to crop stems, selected weeds or to the soil to avoid contact with crop foliage.
Active compounds having different mechanisms of action are combined to delay the generation of resistance and reduce the amount of application and prevention and treatment costs. Consequently, research is being conducted to produce herbicides and combinations of herbicides that are safer, that have better performance, that require lower dosages, that are easier to use, and that cost less.
Accordingly, there is a need in the art to provide synergistic herbicidal compositions which are environmentally safer and stable product during storage.
The present invention is based on the synergistic effect of bixlozone, metribuzin and oxyfluorfen when applied in combination.
The synergistic herbicidal composition of the present invention shows enhanced herbicide action in comparison with the herbicide action of solo bixlozone, metribuzin and oxyfluorfen against undesirable vegetation. Moreover, the composition of the invention shows a persistent herbicidal activity, even under difficult weathering conditions, and minimizes the risk of weeds escaping. The composition is generally non-toxic or of low toxicity against mammals. Apart from that, the composition of the present invention shows superior crop compatibility with certain conventional crop plants and with herbicide tolerant crop plants, i.e., their use in these crops leads to a reduced damage of the crop plants and/or does not result in increased damage of the crop plants. Thus, the combinations of the invention can also be applied after the emergence of the crop plants.
The synergistic herbicidal composition of the present invention may also show an accelerated action on harmful plants, i.e., they may affect damage of the harmful plants more quickly in comparison with solo or binary applications of the at least three herbicides involved.

SUMMARY OF THE INVENTION

The present invention is to provide a synergistic herbicidal composition comprising a mixture of an isoxazolidinone herbicide, a triazinone herbicide, a diphenyl ether herbicide in effective amounts, along with suitable agrochemical additives.
According to the present invention, an isoxazolidinone herbicide is bixlozone, a triazinone herbicide is metribuzin, a diphenyl ether herbicide is oxyfluorfen.
In one aspect the present invention provides a synergistic herbicidal composition comprising of (a) bixlozone, (b) metribuzin, and (c) oxyfluorfen with suitable agrochemical additives.
In another aspect the present invention provides a synergistic herbicidal composition comprising of a) bixlozone is present in a range from 30% (w/w) to 40% (w/w); b) metribuzin is present in a range from 8% (w/w) to 12% (w/w); c) oxyfluorfen is present in a range from 2% (w/w) to 6% (w/w); and d) suitable agrochemical additives.
According to the present invention, the suitable agrochemical additives are selected from the group comprising a wetting agent, a dispersing agent, a disintegration agent, a defoamer, an anticaking agent, and a filler.
According to the present invention, the wetting agent is selected from the group comprising of sodium isopropyl naphthalene sulfonate, naphthalene sulfonic acid and phenol sulphonic acid sodium salt, iso decyl alcohol ethoxylates, sodium lauryl sulphate, present in a range from 1% to 3% (w/w).
According to the present invention, the dispersing agent is selected from the group comprising of alkyl naphthalene sulfonate formaldehyde condensate, sodium ligno sulphonates, kraft lignin polymer, mixture of naphthalene sulfonic acid and phenol sulphonic acid condensate sodium salt, modified styrene acrylic polymer, alkyl naphthalene sulphonate sodium salt, kraft lignin sulphonate, and combination thereof, present in a range from 1% to 10% (w/w).
According to the present invention, the disintegration agent is selected from ammonium sulphate, and sodium sulfate, present in a range from 10% to 25% (w/w).
According to the present invention, the defoamer is polydimethyl siloxane, present in a range from 0.1% to 2% (w/w).
According to the present invention, an anti-caking agent is silicon dioxide, present in a range from 0.1% to 5% (w/w).
According to the present invention, the filler is selected from china clay, starch, and aluminium hydroxide, present in Q.S.
In an aspect of the present invention, the composition is formulated as water dispersible granule (WDG).
In another aspect the present invention provides a process for the preparation of an herbicidal composition comprising of bixlozone, metribuzin and oxyfluorfen.
In another aspect the present invention provides a synergistic herbicidal composition of bixlozone, metribuzin and oxyfluorfen with an improved stability and ready to use herbicidal composition, having superior bio-efficacy compared to the individual formulations.
In another aspect the present invention provides a synergistic herbicidal composition of bixlozone, metribuzin and oxyfluorfen for wheat crops through pre-emergent application for the control of grass and broad-leaf weeds.
In yet another aspect the present invention provides a synergistic herbicidal composition of bixlozone, metribuzin and oxyfluorfen for crops through pre-emergent and post-emergent application for the control of grass and broad-leaf weeds, particularly in wheat crop.
In yet another aspect the present invention provides a synergistic herbicidal composition comprising of bixlozone, metribuzin and oxyfluorfen to enable efficient and reliable control of grass and broad-leaf weeds.

DETAILED DESCRIPTION OF THE INVENTION

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.
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.
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.
The expression of various quantities in terms of “% w/w” or “%” means the percentage by weight, relative to the weight of the total composition unless otherwise specified.

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.
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.
As used herein, the terms “herbicide” may be understood as a substance that is toxic to plants, used to destroy unwanted vegetation.
As used herein, “controlling undesirable vegetation” means preventing, reducing, killing, or otherwise adversely modifying the development of plants and vegetation. Described herein are methods of controlling undesirable vegetation through the application of certain herbicide combinations or compositions. Methods of application include, but are not limited to applications to the vegetation or locus thereof, e.g., application to the area adjacent to the vegetation, as well as pre-emergence, post-emergence, foliar (broadcast, directed, banded, spot, mechanical, over-the-top, or rescue), and in-water applications (emerged and submerged vegetation, broadcast, spot, mechanical, water-injected, granular broadcast, granular spot, shaker bottle or stream spray) via hand, backpack, machine, tractor, or aerial application methods.
As used herein, the term “agrochemical additives” may be understood to include a range of surfactants, dispersing agents, organic or inorganic pigments, solvents, de-solvents, defoamers, emulsions, crystallization inhibitors, viscosity modifiers, suspending agents, dyes, antioxidants, foaming agents, light absorbers, mixing aids, neutralizers or pH adjusting substances and buffers, corrosion inhibitors, wetting agents, absorption enhancers, micronutrients, plasticizers, lubricants, thickeners, anti-freezing agents, sterilization agents among others.
Bixlozone is a new herbicide from the isoxazolidinone family and provides unique selective residual weed control solution in a wide range of crops including, cereals, corn, legumes, oilseed rape, rice, and sugarcane, and offer a new mode of action for many of these crops. Bixlozone provides both systemic and contact activity, with residual control and can be applied pre-emergence, early post-emergence or incorporated by sowing, across a wide range of agronomic environments. It controls major problematic grass weeds including ryegrass and blackgrass, and several key broadleaf weeds by inhibiting 1-deoxy-D-xylulose 5-phosphate synthase resulting in the disruption of plastid isoprenoid biosynthesis. It is proposed to be classified as an HRAC Group F4 and will offer a new rotational product tool for resistance management.
Metribuzin is a synthetic organic compound and a widely used herbicide applied in preemergence and postemergence on intensive vegetable crops. It is known for its efficiency and relatively low toxicity. Metribuzin is slightly soluble in water, and slightly soluble in several organic solvents. Because it is available for runoff, contamination of soil, groundwater, and surface waters has been reported. Metribuzin and its degradants are persistent and mobile.
Metribuzin is used both pre- and post-emergence in crops including soyabean, potatoes, tomatoes, and sugar cane.
Oxyfluorfen is a selective pre- and post-emergent herbicide used to control broadleaf and grassy weeds in a variety of nut, tree fruit, vine, and field crops, especially wine grapes and almonds. It is also used for residential weed control. It is a contact herbicide and light is required for it to affect the target plant. It is available in emulsifiable concentrate and granular formulations.
The herbicidal composition of the present invention may be formulated as 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), tablet (TB), water dispersible granules (WG or WDG), 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) among others. Preferably, the composition of the present invention is in form of water dispersible granule (WDG).
In an embodiment the present invention provides a synergistic herbicidal composition comprising a mixture of an isoxazolidinone herbicide, a triazinone herbicide, a diphenyl ether herbicide in effective amounts, along with suitable agrochemical additives.
According to the present embodiment, an isoxazolidinone herbicide is bixlozone, a triazinone herbicide is metribuzin, a diphenyl ether herbicide is oxyfluorfen.
The present invention provides a synergistic herbicidal composition comprising of (a) bixlozone, (b) metribuzin, and (c) oxyfluorfen with suitable agrochemical additives.
In an embodiment the present invention provides a synergistic herbicidal composition comprising of a) bixlozone present in a range from 30% (w/w) to 40% (w/w); b) metribuzin present in a range from 8% (w/w) to 12% (w/w); c) oxyfluorfen present in a range from 2% (w/w) to 6% (w/w), and d) suitable agrochemical additives.
According to the present embodiment, the suitable agrochemical additives are selected from the group comprising a wetting agent, a dispersing agent, a disintegration agent, a defoamer, an anticaking agent, and a filler.
Wetting is the first stage of dispersion, in which the air surrounding the granular composition is substituted with water. Wetting of the herbicidal composition with water cannot occur if the surface tension of the liquid is very high. Hence, it is recommended to add a wetting agent to the herbicidal composition to facilitate the process of dispersion of the granules in the liquid.
Accordingly, the composition of the present invention contains a wetting agent selected from the group comprising of sodium isopropyl naphthalene sulfonate, naphthalene sulfonic acid and phenol sulphonic acid sodium salt, iso decyl alcohol ethoxylates, sodium lauryl sulphate, present in a range from 1% to 3% (w/w).

It is generally observed that solid particles in a liquid undergo spontaneous aggregation to form lumps. Hence it is recommended to add a dispersant or a dispersing agent which prevents aggregation of solid particles and keeps them suspended in the fluid.
Accordingly, the composition of the present invention contains a dispersing agent is selected from the group comprising of alkyl naphthalene sulfonate formaldehyde condensate, sodium ligno sulphonates, kraft lignin polymer, mixture of naphthalene sulfonic acid and phenol sulphonic acid condensate sodium salt, modified styrene acrylic polymer, alkyl naphthalene sulphonate sodium salt, kraft lignin sulphonate, and combination thereof, present in a range from 1% to 10% (w/w).
The alkyl naphthalene sulfonates to be used in the compositions preferably have alkyl groups with 1 to 10 carbon atoms, such as methyl, isopropyl, n-butyl, sec-butyl, and nonyl. Especially preferred products are sodium butyl naphthalene sulfonate and sodium nonyl naphthalene sulfonate.
Disintegrating agent are additive that can be some time useful for improving dispersibility of herbicide formulation. Accordingly, the composition of the present invention contains a disintegrating agent selected from ammonium sulphate, and sodium sulfate, present in a range from 10% to 25% (w/w).
Defoamer is a chemical reagent developed for defoaming and foam suppression based on the principle of foaming. The defoamer suitable for the purpose of the present invention is polydimethyl siloxane, present in a range from 0.1% to 2% (w/w).
An anti-caking agent is an additive used in the pesticide industry to avoid the formation of lumps. The anti-caking agent suitable for the purpose of the present invention is silicon dioxide, present in a range from 0.1% to 5% (w/w).
A “filler” refers to solid chemicals that are added to an herbicide formulation to aid in the delivery of the active ingredient. Accordingly, the composition of the present invention contains a filler selected from china clay, starch, and aluminium hydroxide, present in Q.S.
In an embodiment of the present invention, the composition is formulated as water dispersible granule (WDG).
In another embodiment, the present invention provides a process for the preparation of an herbicidal composition comprising bixlozone, metribuzin and oxyfluorfen.
In another embodiment, the present invention provides a synergistic herbicidal composition for wheat crops through pre-emergent application for the control of grass and broad-leaf weeds.
In yet another embodiment, the synergistic herbicidal composition of the present invention helps in controlling undesired vegetation when applying before and after germination of undesired vegetation, i.e. as pre-emergence (before weed and crop germination), post-emergence (after weed and crop germination)

In yet another embodiment, the synergistic herbicidal composition of the present invention is effective for controlling undesired vegetation including weeds such as grassy weeds, broad leaved weeds, and sedges; and a one-shot formulation effective for controlling undesired vegetation including weeds such as grassy weeds, broad leaved weeds, and sedges.

In yet another embodiment, the synergistic herbicidal composition of present invention has improved stability and is a ready to use herbicidal composition, having superior bio-efficacy compared to the individual formulations.

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

The synergistic herbicidal composition of the present invention and method provided may be utilized to control weeds or battle undesired vegetation in crops or other settings, including but not limited to turf, citrus, grapes, olives, sugarcane, maize, soyabeans, wheat, triticale, potatoes, barley, asparagus, tomatoes, peas, lentils, non-cropped areas, and industrial vegetation management. Preferably, the undesirable vegetation includes species from the families of broadleaved and grass weeds, more preferably from the families of Aeschynomene, Ageratum, Amaranthus, Bidens, Brachiaria, Cenchrus, Cyperus, Digitaria, Echinochloa, Eclipta, Eleusine, Eragrostis Fimbristylis, Galinsoga, Ischaemum, Leptochloa, Monochoria, Panicum, Paspalum, Polygonum, Portulaca, Richardia, Sesbania, Setaria, Sida, Sorghum, most preferably Echinochloa, Leptochloa, Ischaemum, Monochoria, and Cyperus, or combinations thereof.
The synergistic herbicidal composition achieves improved biological activity by enhancing overall control of weeds over a shorter period. Additional benefits of using the herbicidal composition of the present invention includes reduced risk of occupational hazard, lower cost of application, better cost: benefit ratio to the end user, reduced fuel, and labour cost, saving in applicator’s time and loss caused by mechanical damage to the crop and soil.
The present synergistic herbicidal compositions can be applied to the undesirable vegetation and/or weeds or their locus using 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.
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.

Examples:
Example 1: Bixlozone 35%+ Metribuzin 10.5% + Oxyfluorfen 4.5% WDG

S. No. Composition Function Charge in (%)
1. Bixlozone 35% Active ingredient 35.0
2. Metribuzin 10.5% Active ingredient 10.5
3. Oxyfluorfen 4.5% Active ingredient 4.5
4. Sodium isopropyl naphthalene sulfonate Wetting agent 3.0
5. Alkyl naphthalene sulfonate formaldehyde condensate Dispersing agent 5.0
6. Ammonium sulphate Disintegrating Agent 15.0
7. Polydimethyl siloxane emulsion Defoamer 0.5
8. Silicon dioxide Anti caking agent 3.0
9. China clay Filler Q.S.

The process for manufacture of the composition is as follows: 35.0 gm of Bixlozone, 10.5 gm of Metribuzin, 4.5 gm of Oxyfluorfen, 3.0 gm of sodium isopropyl naphthalene sulfonate, 5.0 gm of Alkyl naphthalene sulfonate formaldehyde condensate, 15.0 gm of Ammonium sulphate, 0.5 gm of polydimethyl siloxane emulsion, 3.0 gm of silicon dioxide, and required quantity 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 < 12 microns). Collecting the milled material and post blending the material for 1 hour. Extruding the granule at 35 rpm (1.0 mesh), collecting the water dispersible granules, and drying at 50 °C for 30 min (moisture content should be < 5%) followed by packing the material in a suitable package.

Example-2: Bixlozone 30%+ Metribuzin 12% + Oxyfluorfen 6% WDG

S. No. Composition Function Charge in (%)
1. Bixlozone 30% Active ingredient 30.0
2. Metribuzin 12% Active ingredient 12.0
3. Oxyfluorfen 6% Active ingredient 6.0
4. Sodium isopropyl naphthalene sulfonate Wetting agent 2.0
5. Alkyl naphthalene sulfonate formaldehyde condensate Dispersing agent 4.0
6. Ammonium sulphate Disintegrating Agent 15.0
7. Polydimethyl siloxane emulsion Defoamer 0.5
8. Silicon dioxide Anti caking agent 3.0
9. China clay Filler Q.S.

The process for manufacture of composition is as follows: 30.0 gm of Bixlozone, 12.0 gm of Metribuzin, 6.0 gm of Oxyfluorfen, 2.0 gm of sodium isopropyl naphthalene sulfonate, 4.0 gm of alkyl naphthalene sulfonate formaldehyde condensate, 15.0 gm of ammonium sulphate, 0.5 gm of polydimethyl siloxane emulsion, 3.0 gm of silicon dioxide, and required quantity 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 < 12 microns). Collecting the milled material and post blending the material for 1 hour. Extruding the granule at 35 rpm (1.0 mesh), collecting the water dispersible granules, and drying at 50 °C for 30 min (moisture content should be < 5%) followed by packing the material in a suitable package.

Example-3: Bixlozone 40%+ Metribuzin 8% + Oxyfluorfen 2% WDG
S. No. Composition Function Charge in (%)
1. Bixlozone 40% Active ingredient 40.0
2. Metribuzin 8% Active ingredient 8.0
3. Oxyfluorfen 2% Active ingredient 2.0
4. Kraft lignin Polymer Dispersing agent 2.0
5. Sodium ligno sulphonates Dispersing agent 3.0
6. Sodium isopropyl naphthalene sulfonate Wetting agent 3.0
7. Ammonium sulphate Disintegrating Agent 15.0
8. Polydimethyl siloxane emulsion Defoamer 0.5
9. Silicon dioxide Anti caking agent 2.0
10. China clay Filler Q.S.

The process for manufacture of composition is as follows: 40.0 gm of Bixlozone, 8.0 gm of Metribuzin, 2.0 gm of Oxyfluorfen, 2.0 gm of kraft lignin polymer 3.0 gm sodium ligno sulphonates, 3.0 gm of sodium isopropyl naphthalene sulfonate, 15.0 gm of ammonium sulphate, 0.5 gm of polydimethyl siloxane emulsion, 2.0 gm of silicon dioxide, and required quantity 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 < 12 microns). Collecting the milled material and post blending the material for 1 hour. Extruding the granule at 35 rpm (1.0 mesh), collecting the water dispersible granules, and drying at 50 °C for 30 min (moisture content should be < 5%) followed by packing the material in a suitable package.

Bio-efficacy study of Bixlozone + Metribuzin + Oxyfluorfen herbicidal combination:

Field and Synergy Studies:
Wheat is the main cereal crop in India. In India, it is grown on an area of 31.6 million hectare with an annual production of 106.84 million tonnes. Successful weed control is most important factor for fruitful wheat production because losses due to weeds have been one of the major limiting factors in wheat production. Weeds compete with crop for light moisture and nutrients. It was concluded that weeds exhibit the economic yield losses to the wheat crop, which may range from 24-39.95% and these must be controlled during the full growing season of the crop for achieving satisfactory crop yields. 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.
The field studies were conducted to compare the weed controlling activity of the combination of Bixlozone, Metribuzin, and Oxyfluorfen. The active ingredient Bixlozone in the combination, belongs to chemical family “Isoxazolidinone” with mode of action of inhibition of Deoxy-D-Xylulose Phosphate Synthase inhibitors, Metribuzin belonging to chemical family “Triazinones” with PS II inhibitor (inhibition of photosystem-II) mode of action and Oxyfluorfen belongs to chemical family “Aryloxy phenoxy-propionates” with PPO (protoporphyrinogen oxidase) inhibitor mode of action. Combination has the potential of controlling the cross-spectrum weeds (broad leaf weeds and grassy weeds) in wheat at the pre-emergence (0-3 DAS) application timing. All the molecules are safe to wheat when applied at their recommended dose rate in pre-emergence (0-3 DAS) application timing.
The weed control activity of the individual herbicides of the invention and their combinations were evaluated on weeds such as Phalaris minor, Chenopodium album, Melilotus alba, Rumex dentatus, Vicia sativa and Lathyrus aphaca. Trials were conducted with randomized block design with net plot size of 5 m x 6 m. 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 pre-emergence application timing. Such field trials were carried out at various locations to generate independent data, the locations were chosen randomly across India.
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.
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 two formulae’s for determining the synergy between 2-way and 3-way combinations, *(Jerry Flint et al, 1988) ***

The synergistic action expected for a given combination of three active components can be calculated as follows:

(AB + AC + BC) ABC
Expected (E) = A + B + C - +
100 10000

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.

The synergistic action expected for given combination of two active components can be calculated as follows:

AB
Expected (E) = A + B –
100
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.

When the percentage of herbicidal 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

The herbicide combinations, application rates, plant species tested, and results are given in the following table:
The field trials were carried out in India at various locations. The percentage efficacy was calculated after 30 days of application. The target weed was Phalaris minor, Chenopodium album, Vicia sativa and Lathyrus aphaca and the synergy effect of three-way combination of Bixlozone, Metribuzin and Oxyfluorfen on weeds in pre-emergence application window are as follows:
Table 1:

Active Dose (GAH) % Weed Control of Phalaris minor % Weed Control of Chenopodium album % Weed Control of Vicia sativa % Weed Control of Lathyrus aphaca
Expected Observed Expected Observed Expected Observed Expected Observed
Bixlozone 40% SC 700 70 10 25 30
Metribuzin 70% WP 210 10 40 45 50
Oxyfluorfen 23.5% EC 90 60 75 75 75
Bixlozone 40% SC + Metribuzin 70% WP 700 + 210 73 72 46 45 58.75 55 65 62
Ratio of O/E 0.98 0.97 0.93 0.95
Metribuzin 70% WP + Oxyfluorfen 23.5% EC 210 + 90 64 63 85 82 86.25 85 87.5 85
Ratio of O/E 0.98 0.96 0.98 0.97
Bixlozone 40% SC + Oxyfluorfen 23.5% EC 700 + 90 88 87 77.5 75 81.25 80 82.5 82
Ratio of O/E 0.98 0.97 0.98 0.99
Bixlozone 35%+ Metribuzin 10.5% + Oxyfluorfen 4.5% WDG 700 + 210 + 90 89.2 95 86.5 90 89.6 95 91.25 95
Ratio of O/E 1.06 1.04 1.06 1.04

Table 2:

Active Dose (GAH) % Weed Control of Phalaris minor % Weed Control of Chenopodium album % Weed Control of Vicia sativa % Weed Control of Lathyrus aphaca
Expected Observed Expected Observed Expected Observed Expected Observed
Bixlozone 40% SC 600 60 10 15 20
Metribuzin 70% WP 240 20 40 55 55
Oxyfluorfen 23.5% EC 120 70 80 80 80
Bixlozone 40% SC+ Metribuzin 70% WP 600+240 68 65 46 45 61.75 60 64 63
Ratio of O/E 0.95 0.97 0.97 0.98
Metribuzin 70% WP + Oxyfluorfen 23.5% EC 240+120 76 75 89 88 91 89.5 91 89
Ratio of O/E 0.98 0.98 0.98 0.97
Bixlozone 40% SC + Oxyfluorfen 23.5% SC 600+120 88 85 81 79 83 82 84 82.5
Ratio of O/E 0.96 0.97 0.98 0.98
Bixlozone 30%+ Metribuzin 12% + Oxyfluorfen 6% WDG 600+240+
120 90.4 92 89.2 93 92.35 95 92.8 95
Ratio of O/E 1.01 1.04 1.02 1.02

Table 3:

Active Dose (GAH) % Weed Control of Phalaris minor % Weed Control of Chenopodium album % Weed Control of Vicia sativa % Weed Control of Lathyrus aphaca
Expected Observed Expected Observed Expected Observed Expected Observed
Bixlozone 40% SC 800 65 20 40 45
Metribuzin 70% WP 160 10 20 25 30
Oxyfluorfen 23.5 % EC 40 45 60 60 55
Bixlozone 40% SC + Metribuzin 70% WP 800+160 68.5 67 36 35 55 52 61.5 60
Ratio of O/E 0.97 0.97 0.94 0.97
Metribuzin 70% WP + Oxyfluorfen 23.5% EC 160+40 45 42 68 67 70 68.5 68.5 67
Ratio of O/E 0.93 0.98 0.97 0.97
Bixlozone 40% SC + Oxyfluorfen 23.5% EC 800+40 86.25 85 68 67 76 75 75.25 74
Ratio of O/E 0.98 0.98 0.98 0.98
Bixlozone 40%+ Metribuzin 8% + Oxyfluorfen 2% WDG 800+160 + 40 82.65 88 74.4 78 82 85 82.67 90
Ratio of O/E 1.06 1.04 1.03 1.08

From the above results in tables 1 to 3 its clearly demonstrates the synergy between of three-way combination of Bixlozone + Oxyfluorfen + Metribuzin WDG against weeds like, Phalaris minor, Chenopodium album & Vicia sativa and Lathyrus aphaca. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination. ,CLAIMS:We Claim:
1. A synergistic herbicidal composition comprising bixlozone, metribuzin, and oxyfluorfen with agrochemical additives.
2. The herbicidal composition as claimed in claim 1, wherein in the composition bixlozone is present in a range from 30% (w/w) to 40% (w/w), metribuzin is present in a range from 8% (w/w) to 12% (w/w), oxyfluorfen is present in a range from 2% (w/w) to 6% (w/w), and agrochemical additives.
3. The herbicidal composition as claimed in claim 1, wherein the composition is formulated as water dispersible granules (WDG) form.
4. The herbicidal composition as claimed in claim 1, wherein the agrochemical additives are selected from a wetting agent, a dispersing agent, a disintegration agent, a defoamer, an anticaking agent, and a filler.
5. The herbicidal composition as claimed in claim 4, wherein the wetting agent is selected from the group comprising of sodium isopropyl naphthalene sulfonate, naphthalene sulfonic acid and phenol sulphonic acid sodium salt, iso decyl alcohol ethoxylates, sodium lauryl sulphate, present in a range from 1% to 3% (w/w).
6. The herbicidal composition as claimed in claim 4, wherein the dispersing agent is selected from the group comprising of alkyl naphthalene sulfonate formaldehyde condensate, Sodium ligno sulphonates, kraft lignin polymer, mixture of naphthalene sulfonic acid and phenol sulphonic acid condensate sodium salt, modified styrene acrylic polymer, alkyl naphthalene sulphonate sodium salt, kraft lignin sulphonate, and combination thereof, present in a range from 1% to 10% (w/w).
7. The herbicidal composition as claimed in claim 4, wherein the disintegration agent is ammonium sulphate, present in a range from 10% to 25% (w/w).
8. The herbicidal composition as claimed in claim 4, wherein the defoamer is polydimethyl siloxane, present in a range from 0.1% to 2% (w/w).
9. The herbicidal composition as claimed in claim 4, wherein the anti-caking agent is silicon dioxide, present in a range from 0.1% to 5% (w/w).
10. The herbicidal composition as claimed in claim 4, wherein filler is china clay, present in Q.S.