FIELD OF THE INVENTION
The present invention relates to an herbicidal composition comprising cyclohexanedione class of herbicide such as clethodim, pyrimidinyl benzoate class of herbicide such as pyrithiobac acid or its salt and diphenyl ether class of herbicide such as oxyfluorfen and agriculturally acceptable additives and uses thereof and process of preparing the herbicidal composition.

BACKGROUND OF THE INVENTION
Weeds and other unwanted vegetation inhibiting crop growth is a constantly recurring problem in agriculture. Therefore, the control of weeds or unwanted plants is economically important for the crop productivity. Researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations as solo or in combination of active ingredients for the control of such weeds or unwanted plants. Formulation of chemical herbicides of many types have been disclosed in the literature and a large number of them are in commercial use.
Currently, in order to reduce the risk from increased number of herbicide resistant varieties of weeds, mixtures of different active compounds are nowadays employed for controlling weeds or unwanted plants as known in art. By combining different active compounds having different mechanisms of action, it is possible to ensure successful control of weeds over a relatively longer period of time and preventing development of resistance. However, this requires continuous development of an effective composition with different active ingredients, so as to avoid selection to the particular mechanism of action.
Therefore, there exists a continuous need to develop an herbicidal composition which is compatible and stable, synergistic, broad spectrum, environmentally safe and more effective in control of weeds in crops. The herbicidal compositions must show a broader scope of activity to avoid or to control the development of resistant varieties to the active ingredients or to the mixtures of known active ingredients used by farmer while minimising the doses of chemical products sprayed in the agricultural fields.
As a solution to the above mentioned problems, the inventors of the present invention surprisingly found that composition comprising clethodim, pyrithiobac acid or its salts and oxyfluorfen provides effective control of wide range of weeds or undesired plants.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a combination comprising of clethodim, pyrithiobac acid or its salts and oxyfluorfen.
In one aspect, the present invention provides a composition comprising of clethodim, pyrithiobac acid or its salts and oxyfluorfen with at least one agriculturally acceptable additive.
In another aspect, the composition according to the present invention comprises clethodim in an amount in the range from 5-25% w/w, pyrithiobac acid or its salts in an amount in the range from 1-15% w/w, and oxyfluorfen in an amount in the range from 5-15% w/w.
In an aspect, the composition of the present invention is formulated as Emulsifiable Concentrate (EC).
In another aspect, the composition of the present invention comprises one or more agriculturally acceptable additives selected from the group comprising of solvent(s), emulsifier(s) or a combination thereof and other additives, if required in a formulation.

DETAILED DESCRIPTION OF THE INVENTION
The definitions provided herein for the terminologies used in the present disclosure are for illustrative purpose only and in no manner limit, the scope of the present invention disclosed in the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although other methods and materials similar, or equivalent, to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.
It is to be noted that, as used in the specification and the appended claims, 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.
As used herein, the terms "comprises", "comprising", "includes", "including", or any other variation thereof, are intended to cover a non-exclusive inclusion, subject to any limitation explicitly indicated. For example, a composition or a method that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, or method.
As used herein, the terms “composition” or "formulation" can be used interchangeably, unless stated otherwise, is meant to encompass, and are not limited to, compositions or formulations containing the combination of clethodim, pyrithiobac acid or its salts and oxyfluorfen thereof.
As used herein, the term “agriculturally acceptable additive (s)” refers to inert substances and are auxiliary substances added to the processing or use of pesticide preparations and used to improve the physical and chemical properties of formulations. The auxiliaries themselves are essentially free of biological activity, but can affect the control effect.
As used herein, the term “solvent(s)” refers to liquids chemicals that are added to an herbicidal product to aid in the delivery of the active ingredient.
As used herein, the term “emulsifier(s)” refers to a group of chemicals belonging to the surfactant family and stabilizes emulsions. Emulsifiers blend and hold together ingredients that would not normally mix very well.
The expression of various quantities in terms of “% w/w” or “%” means the percentage by weight, relative to the weight of the total solution or 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 or undesired plants.
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 weeds. 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.
As used herein, the term “herbicide”, refers to any chemical substance used to destroy/kill, delay, reduce, inhibit or otherwise adversely affect the growth of plants, especially weeds.
As used herein, the term “clethodim” encompasses its agrochemically acceptable salts, derivatives or isomeric form or any other modified form of clethodim. Clethodim having IUPAC name (5RS)-2-[(1EZ)-1-[(2E)-3-chloroallyloxyimino] propyl]-5-[(2RS)-2-(ethylthio) propyl]-3-hydroxycyclohex-2-en-1-one, belongs to the group of cyclohexanedione oxime herbicide. It acts by inhibition of acetyl-coenzyme A carboxylase. It is a rapidly absorbed and readily translocated from treated foliage to the root system and growing parts of the plant. It is used for post-emergence control of annual and perennial grass weeds in a wide range of broad leaved crops, including soybeans, cotton, flax, sunflowers, alfalfa, peanuts, oilseed rape, sugar beets, tobacco, potatoes, vegetables, trees and vines.
As used herein, the term “pyrithiobac acid or its salts” encompasses its agrochemically acceptable salts, derivatives or any other modified form of pyrithiobac acid. Pyrithiobac acid having IUPAC name 2-chloro-6-(4,6-dimethoxypyrimidin-2-ylthio)benzoic acid belongs to the group of pyrimidinyl benzoate class of herbicide. It acts by inhibition of Acetolactate Synthase (ALS) or Acetohydroxy Acid Synthase (AHAS) inhibitor. Selectivity is based on differing rates of metabolism. It is rapidly absorbed by both roots and foliage and translocated in both the xylem and phloem to the site of action at the growing points. It is used as a broad spectrum of selectivity and is used at low rates as pre-emergence or post-emergence treatments in many cropping systems, trees and vines, roadsides, range and pasture, turf, and vegetation management, mainly to control annual grasses and broadleaf weeds in cotton.
As used herein, the term “oxyfluorfen” encompasses its agrochemically acceptable salts, derivatives or any other modified form of oxyfluorfen. Oxyfluorfen having IUPAC name 2-chloro-?,?,?-trifluoro-p-tolyl 3-ethoxy-4-nitrophenyl ether belongs to the group of diphenyl ether herbicide. It acts by inhibition of protoporphyrinogen oxidase (PPO). It is absorbed more readily by foliage (and especially the shoots) than by roots with very little translocation. It is used for pre-emergence and post-emergence control of annual broad leaved and grass weeds in tree fruit, citrus, vines, nuts, cereals, maize, soybeans, peanuts, rice, cotton, bananas, peppermint, onions, garlic, ornamentals and conifer seedbeds.
Accordingly, the present invention provides a combination of clethodim, pyrithiobac acid or its salts and oxyfluorfen.
In an embodiment, the present invention provides a synergistic herbicidal composition comprising of clethodim, pyrithiobac acid or its salts and oxyfluorfen and at least one agriculturally acceptable additive.
It has been surprisingly found that composition comprising of clethodim, pyrithiobac acid or its salts and oxyfluorfen not only provides effective control of weeds or undesired plants but also such combination is synergistic in nature.
In an embodiment, the composition according to the present invention comprises clethodim in an amount in the range from 5-25% w/w, pyrithiobac acid or its salts in an amount in the range from 1-15% w/w, and oxyfluorfen in an amount in the range from 5-15% w/w.
In yet another embodiment, the composition of the present invention is selected from a group comprising:
clethodim present in an amount 12% w/w, pyrithiobac sodium present in an amount 6.25% w/w and oxyfluorfen present in an amount 8% w/w and at least one agriculturally acceptable additive.
clethodim present in an amount 5% w/w, pyrithiobac sodium present in an amount 15% w/w and oxyfluorfen present in an amount 15% w/w and at least one agriculturally acceptable additive.
clethodim present in an amount 18% w/w, pyrithiobac sodium present in an amount 7.5% w/w and oxyfluorfen present in an amount 6.25% w/w and at least one agriculturally acceptable additive.
clethodim present in an amount 25% w/w, pyrithiobac sodium present in an amount 1% w/w and oxyfluorfen present in an amount 5% w/w and at least one agriculturally acceptable additive.
clethodim present in an amount 15% w/w, pyrithiobac sodium present in an amount 10% w/w and oxyfluorfen present in an amount 10% w/w and at least one agriculturally acceptable additive.
In yet another embodiment, the composition of the present invention is formulated as Emulsifiable Concentrate (EC).
The composition of the present invention comprises agriculturally acceptable additives selected from the group comprising of solvent(s), emulsifier(s), or a combination thereof and other additives, if required in a formulation.
Solvent(s) is selected from the group comprising of, but not limited to alcohols such as ethanol, propanol, butanol, n-octanol, isopropanol, glycol ether based solvent such as ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerine; polyol ethers such as ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, dipropylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone; ethers such as dipropyl ether, dioxane, tetrahydrofuran; aliphatic hydrocarbons such as normal paraffin, isoparaffin, kerosene, mineral oils; vegetable oils such as epoxidized soybean oil (ESBO/ESO); aromatic hydrocarbons such as solvent naphtha, aromatic heavy naphtha, solvent C9, solvent C10, solvent C12, solvesso 100, solvesso 150, solvesso 200; chlorinated aliphatic or aromatic hydrocarbons such as chlorobenzene, chloroethylene, methylene chloride; esters such as ethyl acetate, diisopropyl phthalate, dimethyl adipate, methyl oleate, methyl tallowate; lactones such as gamma-butyrolactone; amides such as dimethylformamide, N-methyl-2-pyrrolidone (NMP), N-octylpyrolidone, decanamide, N,N-dimethyldecanamide; nitriles such as acetonitrile; organosulfur compound such as dimethyl sulfoxide. These solvents may be used alone or in combination thereof or as a co-solvent and combination of solvents. The solvent(s) may be used in an amount of quantity sufficient to make 100%w/w formulation.
Emulsifier is selected from the group comprising of, but not limited to, Polyalkylene oxide block copolymer, High molecular weight polymer, PEG-10, PPG-5 cetyl phosphate, nonionic emulsifier such as Tristyryl phenolethoxylate, Blend of nonionic-anionic emulsifiers such as castor oil ethoxylates, alkoxylated alcohols, ethoxylated amines, ethoxylated tristyrylphenol, fatty acid ethoxylates, calcium salts of dodecylbenzene sulphonate, salts of phosphate esters of ethoxylated tristyrylphenol. These emulsifiers may be used alone or in combination thereof. The emulsifier is present in an amount in the range from 1 to 20% w/w.
The composition of the present invention can be applied by any one of the methods selected from atomization, spreading, dusting, spraying, diffusion, immersion, irrigation, injection, mixing, sprinkling (water immersion), foaming, dressing, coating, blasting, fumigation, smoking, smog and painting.
The present invention also provides a process of preparing a composition comprising: a) clethodim, pyrithiobac acid or its salts and oxyfluorfen and b) at least one agriculturally acceptable additive.
In another embodiment, the composition of the present invention is effective in the management of post-emergent, monocotyledonous and dicotyledonous weeds.
In an embodiment of the present invention, the composition used for the post-emergence control of variety of crops, including but not limited to, weeds in cotton, soybean, cereals, oilseeds, fibre crops, sugar crops, sugarcane, rubber, oil palms, non-crop land, as well as protecting crops from herbicidal injury caused by any of the individual components.
The rate of dosage of formulation varies depending on, for example, the blending ratio of active ingredients, meteorological condition, a dosage form, application time, application method, application place, weed to be controlled, and a target crop, in ordinary cases.

The synergistic composition of the present invention provides a number of other advantages:
Increased efficacy in comparison to the other formulations tested during the trial.
Economically beneficial to the farmers as it provides better yield of the crop with reduction in the number of sprays.
Reduction in quantity of water required for sprays.
Reduced possibility of hazards to the farmers due to occupational exposure because of reduction in the number of sprays.
Is storage stable.
Is non-phytotoxic.
Environmental friendly.
Easily applied using drone or by any other aerial means.
Reduction in generation of empty pesticide containers, thereby, reducing environmental concerns for their disposal.
The embodiments of the present invention are more particularly described in the following examples that are intended as illustrations only, since numerous modifications and variations within the scope of the present invention will be apparent to those of skilled in the art. Unless otherwise noted, all parts, percentages and ratio reported in the following examples are on a weight basis and all agriculturally acceptable additive used in the examples were obtained or are available from the chemical suppliers.
EXAMPLES
The synergistic herbicidal composition of the present invention comprising a) clethodim, pyrithiobac acid or its salts and oxyfluorfen and b) at least one agriculturally acceptable additives to make Emulsifiable Concentrate (EC) formulation is provided in table 1-2 and example 1 to 5. The unit of each component of the composition are expressed in “% w/w” i.e. the percentage by weight, relative to the weight of the total solution or composition.
Examples 1 to 5
Table 1: Clethodim + Pyrithiobac Sodium + Oxyfluorfen EC
S. N. Ingredients Eg: 1 Eg: 2 Eg: 3 Eg: 4 Eg: 5
% w/w % w/w % w/w % w/w % w/w
1 Clethodim Technical (100% Basis) 12 5 18 25 15
2 Pyrithiobac Sodium Technical (100% Basis) 6.25 15 7.5 1 10
3 Oxyfluorfen Technical (100% Basis) 8 15 6.25 5 10
4 Emulsifier (Blend of non-ionic and anionic examples: castor oil ethoxylates, alkoxylated alcohols, ethoxylated amines, ethoxylated tristyrylphenol, fatty acid ethoxylates, calcium salts of dodecylbenzene sulphonate, salts of phosphate esters of ethoxylated tristyrylphenol etc.) 10 14 12 12 14
5 Co-solvent (NMP, butanol, cyclohexanone vegetable oil) 10 15 10 10 15
6 Solvent (aromatic heavy naptha, C-9, glycol ether based solvent, decanamide, isophorone etc.) Q.S. to make 100% Q.S. to make 100% Q.S. to make 100% Q.S. to make 100% Q.S. to make 100%
Total 100 100 100 100 100
Q.S.: quantity sufficient required to make 100% w/w formulation
Process of preparing synergistic Emulsifiable Concentrate (EC) herbicidal composition comprising Clethodim + Pyrithiobac Sodium + Oxyfluorfen
Table 2 provides quantities of active ingredients and raw material charged to prepare the synergistic herbicidal composition of the present invention in Emulsifiable Concentrate form. In table 2, active ingredients Clethodim + Pyrithiobac Sodium + Oxyfluorfen each are in technical grades form and their purity considered accordingly to make the formulation. Example 1-5 of table 1 corresponds to column A-E in table 2.

Table 2: Quantities of active ingredients and raw material charged
S. N. Ingredients Quantity (g)
A
B C D E
1 Clethodim Technical (37% Basis) 32.44 13.52 48.65 67.57 40.55
2 Pyrithiobac Sodium Technical (95% Basis) 06.58 15.79 07.90 01.06 10.53
3 Oxyfluorfen Technical (97% Basis) 08.25 15.47 06.45 05.16 10.31
4 Emulsifier (Blend of non-ionic and anionic) 10.00 14.00 12.00 12.00 14.00
5 Co-solvent (NMP) 10.00 15.00 10.00 10.00 15.00
6 Solvent (aromatic heavy naptha) 32.73 26.22 15.00 04.21 09.61
Total 100.00 100.00 100.00 100.00 100.00

The ingredients were weighed and taken as per table 2. In a container, solvent and co-solvent were taken and Clethodim, Pyrithiobac Sodium and Oxyfluorfen were added under stirring. Emulsifier was added under stirring. The mixture was stirred to obtain a homogeneous solution. The homogenous solution was filtered to obtain title herbicidal composition.
Bio-efficacy of the herbicidal composition of the present invention
Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC
Experimental trial was conducted to evaluate the herbicidal composition of the present invention in India against major weeds in cotton crop in variety Bio Seed 11 with solo and binary formulations for comparison and ternary formulations of the present invention as per the details provided in Table 3-8.
The experiment was laid out in Randomized Block Design (RBD). The plot size was 10 m x 10 m and the spacing was 90 cm × 60 cm. All the recommended agronomic practices were followed throughout the cropping period. A separate area of 0.5 x 0.5 m was marked in each plot and the species-wise weed (broad leaved and grassy weeds separately) in each marked quadrant were removed at 15, 30, 45 and 60 days after application of herbicide (DAHA) and oven dried at 80? for 72 hours and weighed to estimate the dry weight of weeds. Using the species-wise weed dry weight recorded at 15, 30, 45 and 60 days after spray of herbicide under absolute control and the respective treatments, the weed control efficiency (% WCE) for each treatment was worked out by using formula given below.
WCE (%) = (Weed dry weight in the untreated plot-Weed dry weight in the treated plot)/(Weed dry weight in the untreated plot) x 100
Yield: The Cumulative yield of Cotton from individual plots leaving aside border rows were separately recorded and expressed in kg ha-1.
Table 3: Treatment Details
S.N Treatments No. Treatment Details
1 T1 Clethodim 12%+Pyrithiobac Sodium 6.25% +Oxyfluorfen 8 % EC
2 T2 Clethodim 25% EC
3 T3 Pyrithiobac Sodium 10% EC
4 T4 Oxyflourfen 23.5% EC
5 T5 Clethodim 25% EC + Pyrithiobac Sodium 10% EC
6 T6 Clethodim 25% EC + Oxyflourfen 23.5% EC
7 T7 Pyrithiobac Sodium 10% EC + Oxyflourfen 23.5% EC
8 T8 Control

Table 4: Effect of treatment on weed control efficiency against Narrow leaved weeds at different days after herbicides application
Treatments Dose 15 DAHA 30 DAHA 45 DAHA 60 DAHA
Formulation, ml/ha a.i., g/ha
T1 1000 120 + 62.5 + 80 86.97 85.81 81.86 80.26
T2 500 120 70.05 67.25 60.52 58.10
T3 625 62.5 20.20 19.18 18.44 17.58
T4 340 80 26.48 23.93 23.19 20.53
T5 500 + 625 120 + 62.5 74.25 70.61 62.94 60.42
T6 500 + 340 120 + 80 77.05 72.63 64.76 63.33
T7 625 + 340 62.5 + 80 31.25 27.75 26.43 23.00
T8 - - - - - -

Table 5: Effect of treatment on weed control efficiency against Sedges at different days after herbicides application
Treatments Dose 15 DAHA 30 DAHA 45 DAHA 60 DAHA
Formulation, ml/ha a.i., g/ha
T1 1000 120 + 62.5 + 80 75.66 74.65 71.22 69.83
T2 500 120 58.14 55.15 49.02 46.48
T3 625 62.5 14.54 13.81 12.91 12.31
T4 340 80 21.98 19.62 18.78 16.42
T5 500 + 625 120 + 62.5 59.40 55.78 49.72 46.52
T6 500 + 340 120 + 80 61.64 57.38 51.16 48.76
T7 625 + 340 62.5 + 80 25.00 21.92 20.88 17.71
T8 - - - - - -

Table 6: Effect of treatment on weed control efficiency against Broad Leaved weeds at different days after herbicides application
Treatments Dose 15 DAHA 30 DAHA 45 DAHA 60 DAHA
Formulation, ml/ha a.i., g/ha
T1 1000 120 + 62.5 + 80 90.79 90.92 89.03 87.29
T2 500 120 11.63 11.58 10.78 10.69
T3 625 62.5 59.61 58.00 55.51 54.16
T4 340 80 50.55 51.01 48.83 47.62
T5 500 + 625 120 + 62.5 62.59 60.90 58.29 56.87
T6 500 + 340 120 + 80 55.10 55.60 53.22 51.90
T7 625 + 340 62.5 + 80 74.45 74.47 72.91 71.58
T8 - - - - - -

Table 7: Effect of treatments on lint yield at harvest
Treatments Dose Lint yield % increase against control
Formulation, ml/ha a.i., g/ha kg/ha
T1 1000 120 + 62.5 + 80 1061 78.02
T2 500 120 752 26.17
T3 625 62.5 727 21.98
T4 340 80 808 35.57
T5 500 + 625 120 + 62.5 772 29.53
T6 500 + 340 120 + 80 818 37.25
T7 625 + 340 62.5 + 80 814 36.58
T8- Control - - 596 -
SEM 9.938 -
CD5% 30.435 -
SEM- Standard error of mean; CD5%: Critical Difference
Separate trials to assess the phyto-toxicity of Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC at different doses were conducted. Results are presented below in table 8a-8d.
Table 8: Phyto-toxicity studies of treatments on Cotton crop

Table 8a: Epinasty

Treatments Treatment Details Dose /ha Epinasty
0 DAHA 1 DAHA 7 DAHA 10 DAHA 15 DAHA
T1 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 800 ml 0 0 0 0 0
T2 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1000 ml 0 0 0 0 0
T3 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1200 ml 0 0 0 0 0
T4 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 2000 ml 0 0 0 0 0
T5 Control - 0 0 0 0 0
0-No Phyto-toxicity 10-Complete kill the plant

Table 8b: Hyponasty

Treatments Treatment details Dose /ha Hyponasty
0 DAHA 1 DAHA 7 DAHA 10 DAHA 15 DAHA
T1 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 800 ml 0 0 0 0 0
T2 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1000 ml 0 0 0 0 0
T3 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1200 ml 0 0 0 0 0
T4 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 2000 ml 0 0 0 0 0
T5 Control - 0 0 0 0 0
0-No Phyto-toxicity 10-Complete kill the plant

Table 8c: Necrosis

Treatments Treatment details Dose /ha Necrosis
0 DAHA 1 DAHA 7 DAHA 10 DAHA 15 DAHA
T1 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 800 ml 0 0 0 0 0
T2 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1000 ml 0 0 0 0 0
T3 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1200 ml 0 0 0 0 0
T4 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 2000 ml 0 0 0 0 0
T5 Control - 0 0 0 0 0
0-No Phyto-toxicity 10-Complete kill the plant

Table 8d: Vein clearing & Wilting

Treatments Treatments Dose /ha Vein clearing & Wilting
0 DAHA 1 DAHA 7 DAHA 10 DAHA 15 DAHA
T1 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 800 ml 0 0 0 0 0
T2 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1000 ml 0 0 0 0 0
T3 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 1200 ml 0 0 0 0 0
T4 Clethodim 12% + Pyrithiobac Sodium 6.25% + Oxyfluorfen 8% EC 2000 ml 0 0 0 0 0
T5 Control - 0 0 0 0 0
0-No Phyto-toxicity 10-Complete kill the plant

Evaluation of synergistic effect
A synergistic effect exists whenever the action of an active ingredient combination is greater than the sum of the actions of the individual components. Synergism was calculated by using Colby’s method, Weeds, vol. 15 No. 1(Jan 1967), pp. 20-2.
The synergistic action expected for a given combination of two active components can be calculated as follows:
?(E=(X+Y) - ((XY))/100 ) ?( )
The synergistic action expected for a given combination of three active components can be calculated as follows:
?(E=(X+Y+Z) - ((XY+YZ+XZ))/100 +) ?( XYZ/10000)
Where:
E represents expected percentage of control for the combination of the two/three active ingredients at defined doses (for example equal to x, y and z respectively),
X is the percentage of control observed by the compound (I) at a defined dose (equal to x),
Y is the percentage of control observed by the compound (II) at a defined dose (equal to y),
Z is the percentage of control observed by the compound (III) at a defined dose (equal to z).
If observed control of the combination > Expected control, the combination is synergistic
If observed control of the combination < Expected control, the combination is antagonistic
If observed control of the combination = Expected control, the combination is additive

Table 9: Synergistic effect of Clethodim 12%+Pyrithiobac Sodium 6.25% +Oxyfluorfen 8% EC composition against Narrow Leaved weeds at different days after herbicides application
*Treatments Dose ml/ha Dose
(a.i. g/ ha) 15 DAHA 30 DAHA 45 DAHA 60 DAHA
Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%)
T1 1000 120 + 62.5 + 80 86.97 82.43 85.81 79.87 81.86 75.27 80.26 72.56
T2 500 120 70.05 - 67.25 - 60.52 - 58.10 -
T3 625 62.5 20.20 - 19.18 - 18.44 - 17.58 -
T4 340 80 26.48 - 23.93 - 23.19 - 20.53 -
T5 500 + 625 120 + 62.5 74.25 76.10 70.61 73.53 62.94 67.80 60.42 65.47
T6 500 + 340 120 + 80 77.05 77.98
72.63 75.09
64.76 69.68
63.33 66.70

T7 625 + 340 62.5 + 80 31.25 41.33 27.75 38.52 26.43 37.35 23.00 34.50
T8 - - - - - - - - - -
*For details Refer Table 3. # Calculated using Colby Formula
Table 10: Synergistic effect of Clethodim 12%+Pyrithiobac Sodium 6.25% +Oxyfluorfen 8 % EC composition against Sedges at different days after herbicides application
*Treatments Dose ml/ha Dose
(a.i. g/ ha) 15 DAHA 30 DAHA 45 DAHA 60 DAHA
Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) Observed
WCE (%)
T1 1000 120 + 62.5 + 80 75.66 72.09 74.65 68.93 71.22 63.94 69.83 60.77
T2 500 120 58.14 - 55.15 - 49.02 - 46.48 -
T3 625 62.5 14.54 - 13.81 - 12.91 - 12.31 -
T4 340 80 21.98 - 19.62 - 18.78 - 16.42 -
T5 500 + 625 120 + 62.5 59.40 64.23 55.78 61.34 49.72 55.60 46.52 53.07
T6 500 + 340 120 + 80 61.64 67.34
57.38 63.95
51.16 58.59
48.76 55.27

T7 625 + 340 62.5 + 80 25.00 33.32 21.92 30.72 20.88 29.27 17.71 26.71
T8 - - - - - - - - - -
*For details Refer Table 3. # Calculated using Colby Formula
Table 11: Synergistic effect of Clethodim 12%+Pyrithiobac Sodium 6.25% +Oxyfluorfen 8 % EC composition against Broad Leaved weeds at different days after herbicides application
*Treatments Dose ml/ha Dose
(a.i. g/ ha) 15 DAHA 30 DAHA 45 DAHA 60 DAHA
Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) #Expected
WCE (%) Observed
WCE (%) Observed
WCE (%)
T1 1000 120 + 62.5 + 80 90.79 82.35 90.92 81.81 89.03 79.69 87.29 78.56
T2 500 120 11.63 - 11.58 - 10.78 - 10.69 -
T3 625 62.5 59.61 - 58.00 - 55.51 - 54.16 -
T4 340 80 50.55 - 51.01 - 48.83 - 47.62 -
T5 500 + 625 120 + 62.5 62.59 64.31 60.90 62.86 58.29 60.31 56.87 59.06
T6 500 + 340 120 + 80 55.10 56.30
55.60 56.68
53.22 54.35
51.90 53.22

T7 625 + 340 62.5 + 80 74.45 80.03 74.47 79.42 72.91 77.23 71.58 75.99
T8 - - - - - - - - - -
*For details Refer Table 3. # Calculated using Colby Formula
It is evident from table 9-11 that the observed weed control efficiency (% WCE) is more than the expected weed control efficiency (% WCE), hence, the composition of present invention is synergistic.
From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the scope of the novel concepts of the present invention. It is to be understood that no limitations with respect to the specific embodiments illustrated is intended or should be inferred. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.

WE CLAIMS:

1. A synergistic herbicidal composition comprising of:
a. Clethodim;
b. Pyrithiobac Sodium;
c. Oxyfluorfen; and
d. agriculturally acceptable additives.

2. The synergistic herbicidal composition as claimed in claim 1, comprising: 5 to 25% w/w of Clethodim; 1 to 15% w/w of Pyrithiobac Sodium; and 5 to 15% w/w of Oxyfluorfen.

3. The synergistic herbicidal composition as claimed in claim 1, wherein the composition is selected from a group comprising:
a. 12% w/w of Clethodim, 6.25% w/w of Pyrithiobac Sodium, 8% w/w of Oxyfluorfen and agriculturally acceptable additives;
b. 5% w/w of Clethodim, 15% w/w of Pyrithiobac Sodium, 15% w/w of Oxyfluorfen and agriculturally acceptable additives;
c. 18% w/w of Clethodim, 7.5% w/w of Pyrithiobac Sodium, 6.25% w/w of Oxyfluorfen and agriculturally acceptable additives;
d. 25% w/w of Clethodim, 1% w/w of Pyrithiobac Sodium, 5% w/w of Oxyfluorfen and agriculturally acceptable additives; and
e. 15% w/w of Clethodim, 10% w/w of Pyrithiobac Sodium, 10% w/w of Oxyfluorfen and agriculturally acceptable additives;

4. The synergistic herbicidal composition as claimed in claim 1, wherein the agriculturally acceptable additives is selected from the group comprising of:
a. emulsifiers present in an amount in the range from 1 to 20% w/w; and
b. solvents present in an amount of quantity sufficient to make 100% w/w formulation.

5. The synergistic herbicidal composition as claimed in claim 4, wherein:
a. the emulsifier is selected from the group comprising blend of non-ionic and anionic such as castor oil ethoxylates, alkoxylated alcohols, ethoxylated amines, ethoxylated tristyrylphenol, fatty acid ethoxylates, calcium salts of dodecylbenzene sulphonate, salts of phosphate esters of ethoxylated tristyrylphenol or a combination thereof; and
b. the solvent is selected from the group comprising butanol, glycol ether based solvent, heavy aromatic naphtha, vegetable oils, decanamide, N-methyl-2-pyrrolidone, isophorone, cyclohexanone, solvent C9 or a combination thereof.

6. The synergistic herbicidal composition as claimed in claim 1, wherein the composition is formulated as Emulsifiable Concentrate (EC).

7. The synergistic herbicidal composition as claimed in claim 1 or 6, wherein the composition is in Emulsifiable Concentrate (EC) form selected from a group comprising:
a. 12% w/w of Clethodim, 6.25% w/w of Pyrithiobac Sodium; 8% w/w of Oxyfluorfen, 10% w/w of blend of non-ionic and anionic emulsifier, 10% w/w of N-methyl-2-pyrrolidone, QS% w/w of heavy aromatic naphtha.
b. 5% w/w of Clethodim, 15% w/w of Pyrithiobac Sodium; 15% w/w of Oxyfluorfen, 14 % w/w of blend of non-ionic and anionic emulsifier, 15% w/w of N-methyl-2-pyrrolidone, QS% w/w of heavy aromatic naphtha.
c. 18% w/w of Clethodim, 7.5% w/w of Pyrithiobac Sodium; 6.25% w/w of Oxyfluorfen, 12% w/w of blend of non-ionic and anionic emulsifier, 10% w/w of N-methyl-2-pyrrolidone, QS% w/w of heavy aromatic naphtha.
d. 25% w/w of Clethodim, 1% w/w of Pyrithiobac Sodium; 5% w/w of Oxyfluorfen, 12% w/w of blend of non-ionic and anionic emulsifier, 10% w/w of N-methyl-2-pyrrolidone, QS% w/w of heavy aromatic naphtha.
e. 15% w/w of Clethodim, 10% w/w of Pyrithiobac Sodium; 10% w/w of Oxyfluorfen, 14% w/w of blend of non-ionic and anionic emulsifier, 15% w/w of N-methyl-2-pyrrolidone, QS% w/w of heavy aromatic naphtha.