DESC:FIELD OF INVENTION
The present invention relates to a herbicidal composition, comprising Clodinafop-Propargyl and Carfentrazone-ethyl in a synergistic ratio and a method for preparing such composition.
BACKGROUND OF THE INVENTION
For controlling unwanted plants, e.g., weeds, in agriculture and related endeavours; it is desirable to treat such plants or the locus thereof with chemical herbicides. A common method of herbicidal treatment in agricultural endeavours is to treat a field to remove or control unwanted vegetation as preparation for planting a crop plant, a method otherwise known as “burndown.” However, single herbicides typically lack the weed control spectrum, e.g., the range of weed species effectively controlled by the herbicide, to fully control the diversity of weeds in a field. Therefore, it is common to apply two or more herbicides simultaneously in order to achieve the desired spectrum of control. To facilitate the simultaneous application of two or more herbicides, it is common to package the different herbicides separately as concentrate formulations, which can be admixed with water in a spray tank by the end user, a method also known as tank-mixing. More conveniently, however, the different herbicides can be co-formulated in a single concentrate formulation, requiring only dilution in water by the end user prior to application by spraying. Such a formulation is often known as a package-mix.
Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant hormones. Herbicides used to clear waste ground, industrial sites, railways and railway embankments are non-selective and kill all plant material with which they come into contact. Further, applying combinations of two or more herbicides simultaneously to a field may be necessary or desired for synergistic effects other than an increased control spectrum. For example, some herbicides have prolonged visual symptomology, that is, it takes a relatively long period of time (i.e., up to two weeks or more) for susceptible plants to show the visual effects of treatment. Generally, such extended periods without any visual indication of herbicidal effectiveness detracts from the commercial value of herbicidal product. Therefore, it is often beneficial to combine two or more herbicides in a tank mix or a package-mix that will provide for more rapid burn down and earlier visual symptomology, thus improving the value of the overall herbicidal product.
Package-mix formulations present numerous challenges to the formulator of agricultural chemicals such as herbicides. For example, the formulation should contain the herbicidal active ingredients for maximum convenience to the end user and to minimize packaging and shipping costs, while keeping the active ingredients within the desired weight ratios with respect to each other. Most importantly, the package-mix formulation must exhibit sufficient physical and chemical stability to have an effective shelf life of at least a few months, preferably at least a year, and ideally at least two years.
Unfortunately, many of such herbicides exhibit phytotoxicity to the desired crop as well as to the weeds or grasses sought to be controlled. Phytotoxic means harmful or lethal to plants. Phytotoxicity is the degree to which a chemical or other compound is toxic to plants. Phytotoxic effects caused by herbicides can be from spray droplets, soil residues or vapors contacting sensitive plants. Plants can also be harmed by herbicides which move off target in water or soil or when sensitive crops are planted in fields too soon after herbicide treatment was applied for a previous crop. Phytotoxic effects ranges from slight burning or browning of leaves to death of the plant. Sometimes the damage appears as leaf cupping, crinkling and speckling, distorted leaves, fruit, flowers or stems. Damage symptoms vary with the herbicide and the type of plant that has been affected. High use rates also result in an accumulation of heavy metals in the soil and surrounding environment. Clearly, chemical methods of treatment are lacking in some respects for the control of weeds in cereals with the herbicides presently being used.
Clodinafop-propargyl (IUPAC name: prop-2-ynyl (R)-2-[4-(5-chloro-3-fluoropyridin-2 -yloxy)phenoxy]propionate is disclosed in EP 248968 and United States Patent No. 4713109 belongs to aryloxyphenoxypropionic group of herbicides having following structure.

Clodinafop-propargyl is a compound possessing reported herbicidal activity against grassy weeds in cereals especially in wheat and barley as well as pulses. It is known that it belongs to the oxy phenoxy acid ester group of herbicides which is fatty acid synthesis inhibitor, by inhibiting acetyl co-enzyme A carboxylase, which is essential for the production of lipids or fatty acids needed for plant growth. The selectivity of this herbicide is based on the difference in the speed of herbicide breakdown in the crop versus the weeds. Clodinafop-propargyl converts from the ester form to the active acid and then to biologically inactive compounds. Grass weeds such as wild oats and wild millet cannot effectively break down clodinafop-propargyl, so they are controlled as a lethal dose accumulates at the meristematic growing points. This is a post emergence, selective systemic grass herbicide and is known to control grasses such as green foxtail, barnyard grass, Persian darnel and volunteer canary seed in wheat crops. However, it is known that clodinafop-propargyl is ineffective against several broadleaved weeds.
US 4881966 teaches a composition comprising clodinafop-propargyl and a safener, which is cloquintocet-mexyl that accelerates the rate of clodinafop-propargyl break down in wheat, thus preventing the accumulation of a lethal dose. However, the disclosed composition is still not effective in controlling the growth of the broadleaved weeds.
A newer class of herbicides different than those set forth above controls plants by disrupting certain functions in the plant cell. These herbicides are known as inhibitors of the enzyme protoporphyrinogen oxidase (commonly known as PPO- inhibitors), which cause disruption of cell membranes by inducing lipid peroxidation, resulting in death to the plant. An example of an herbicidal PPO-inhibitor is carfentrazone-ethyl, having the following structure:

Carfentrazone-ethyl (IUPAC name: ethyl-(RS)-2-chloro-3-[2-chloro-5-(4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl)-4-fluorophenyl]propionate is disclosed and claimed in US Patent 5,125,958.
It was further found that a major problem with clodinafop-propargyl is that it undergoes hydrolysis in the presence of an aqueous medium in acidic environment rendering it incapable of being formulated as stable formulation along with carfentrazone-ethyl as a stable soluble liquid formulation.
Hitherto, no successful attempts have been made to formulate a combination of clodinafop-propargyl and carfentrazone-ethyl. Therefore, there is a long felt need in the art to provide a stable formulation comprising clodinafop-propargyl and carfentrazone-ethyl that solves the problems mentioned above and solves the existing problem of phytotoxicity induced by these active ingredients.
SUMMARY OF THE INVENTION
According to an embodiment of the present invention, there is provided a method for controlling different weed spectra in a crop, comprising narrow leaved (monocot) and broad leaved (dicot) weeds in a habitat, breeding grounds or locus with a synergistically effective amount of a combination of clodinafop-propargyl and carfentrazone-ethyl.
According to another embodiment of the present invention, there is provided a synergistic herbicidal mixture comprising a herbicidally effective amount of clodinafop-propargyl and carfentrazone-ethyl.
According to another embodiment of the present invention, there is provided a formulation comprising clodinafop-propargyl and carfentrazone-ethyl in a weight ratio from 5:1 to 1:2.
According to another embodiment of the present invention, clodinafop-propargyl is present in the range from 5 to 50%.
According to another embodiment of the present invention, carfentrazone-ethyl is present in the range from 1.0 to 10%.
According to another another embodiment of the present invention, there is provided a synergistic herbicide composition in the form of a water dispersible granule (WGD), further comprising wetting agents, dispersing agents, and fillers.
According to another another embodiment of the present invention, there is provided a synergistic herbicide composition in the form of an emulsifiable concentrate (EC), further comprising emulsifiers, dispersing agents, co-solvents, stabilizers, and solvents.
According to another embodiment of the present invention the synergistic herbicidal composition may be formulated as dust, powder, granules, encapsulated granules, emulsifiable concentrate, pellets, tablets, dry flowable, wettable powder, water dispersible granules and more preferably formulated as emulsifiable concentrate (EC) and water dispersible granules (WDG).
According to another embodiment of the present invention, there is provided a process of preparing water dispersible granular (WDG) composition, comprising the steps of: (a) admixing wetting agent, dispersing agent and filler in a mixing vessel to form a first mixture; (b) homogenizing the first mixture to a powder; (c) admixing said powder, active ingredients and safener to form a second mixture; (d) extruding the second mixture in the form of granules; and (e) drying the granules.
According to another embodiment of the present invention, there is provided a process of preparing emulsifiable concentrate (EC), comprising the steps of: (a) admixing clodinafop-propargyl, carfentrazone-ethyl, safener, solvent, co-solvent, and dispersing agent in a mixing vessel to form a first homogenous liquid; (b) admixing the first homogenous liquid with emulsifiers and stabilizers to form a second homogenous liquid; (c) filtering the second homogenous liquid to form the emulsifiable concentrate (EC).

DETAILED DESCRIPTION OF THE INVENTION
The invention according to its various aspects is particularly pointed out and distinctly claimed in the appended claims read in view of this specification and appropriate equivalents.
It is to be noted, 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. The expression of various quantities in terms of “% w/w” means the percentage by weight, relative to the weight of the total composition unless otherwise specified.
As used herein Gr formulation, CG formulation, DF formulation, WP formulation, WDG formulation, SL formulation, SC formulation and EC formulation are the international denominations adopted by the FAO (Food and Agriculture Organization of the United Nations) to designate granules, encapsulated granules, dry flowable, wettable powder, water dispersible granules, soluble liquid, suspension concentrate and emulsifiable concentrate, respectively.
The term "agro chemically effective amount" is that quantity of active agent, applied in any amount which will provide the required control of broad leaved weeds and grasses. The particular amount is dependent upon many factors including, for example, the crop, weeds sought to be controlled and environmental conditions. The selection of the proper quantity of active agent to be applied, however, is within the expertise of one skilled in the art.
There is provided a novel synergistic herbicidal composition comprising carfentrazone-ethyl and clodinafop-propargyl. There is also provided a method for controlling different weed spectra in a crop, comprising narrow leaved (monocot) and broad leaved (dicot) weeds in a habitat, comprising the step of treating the grounds or locus with a synergistically effective amount of clodinafop-propargyl and carfentrazone-ethyl. Such a synergistic herbicide composition enhances performance of weed control thereby reducing the required application frequency of the composition to control the grassy and broadleaved weeds in a crop field. Such a synergistic herbicid composition also negates the need for the sequential application of herbicides thereby reducing the environmental load of herbicides and thus are environmentally safe. Such a synergistic herbicid composition not only controls grassy and broadleaf weed population in a crop field but also enhances the vigour/yield of the plant. The synergistic herbicidal composition is also non-phytotoxic to the crops.
The herbicidal composition comprises clodinafop-propargyl and carfentrazone-ethyl in a ratio of 5:1 to 1:2, wherein clodinafop-propargyl is present in the range from 5 to 50% and carfentrazone-ethyl is present in the range from 1.0 to 10%.
The synergistic herbicidal composition may be formulated as granules, encapsulated granules, dry flowable, wettable powder, water dispersible granules, soluble liquid and emulsifiable concentrate, and more preferably formulated as emulsifiable concentrate (EC) and water dispersible granules (WDG).
The synergistic herbicidal composition further comprises a plurality of different ingredients such as wetting agents, dispersing agents, and fillers for water dispersible granules (WDG) and emulsifiers, dispersing agents, co-solvents, stabilizers, and solvents for the emulsifiable concentrate (EC).
The novel herbicidal composition of present investigation provides a wide spectrum control of weeds, delaying the pre-eminence of resistant strains, minimizing the risk of development of resistance, achieving desired storage stability along with effective and economical control of undesired vegetation.
The present invention is more particularly described in the following examples that are intented as illustrations only, since numerous modifications and variations within the scope of the present invention will be apparent to those of skill in the art. Unless otherwise noted, all parts, percentages, and ratios reported in the following examples are on a weight basis and all reagent used in the example were obtained or are available from the chemical suppliers.
EXAMPLES
The following examples illustrate embodiments of the proposed invention that are presently best known. However, other embodiments can be practiced that are also within the scope of the present invention. All of the agrochemical formulations, according to the scope of the present invention and exemplified below had excellent storage stability properties.
Example 1:
Table 1: Synergistic herbicidal composition of Clodinafop-propargyl and Carfentrazone-ethyl water dispersible granules (WDG).
S. No. Component Function Example
(DF)
1 Clodinofop-propargyl Active Ingredient 15.00
2 Cloquintocet mexyl Safener 4.00
3 Carfentrazone-ethyl Active Ingredient 5.00
4 Lignosulfonate acid, sodium salt Wetting Agent 12.00
5 Alkyl polyglycoside Dispersing Agent 2.00
6 Precipitated silica Filler 5.00
7 China clay Filler Q.S.
Q.S.= quantity sufficient
Table 2: Synergistic herbicidal combination of Clodinafop-propargyl and Carfentrazone-ethyl emulsifiable concentrate (EC) formulation
S. No. Component Function Example
(EC)
1 Clodinafop-propargyl Active Ingredient 15.00
2 Cloquintocet-mexyl Safener 6.00
3 Carfentrazone-ethyl Active Ingredient 5.00
4 Mixture of anionic and non-ionic derivatives Emulsifier 5.30
5 Tristyrylphenol ethoxylate Dispersing Agent 4.70
6 N-methyl-2-pyrrolidone Co-solvent 5.00
7 Ethoxylated Soybean Oil Stabilizer 3.00
8 Solvent C-IX Solvent Q.S.
Q.S.= quantity sufficient

Example 2
Process of manufacturing of synergistic herbicidal combination of Clodinafop-propargyl and Carfentrazone-ethyl:
The noval herbicidal composition(s) of Example 1 are prepared by the process described hereinafter. The process of manufacture 100 kg batch size of herbicidal composition comprising clodinafop-propargyl and carfentrazone-ethyl is provided.
Process 1: Process of manufacturing of Clodinafop-propargyl and Carfentrazone-ethyl water dispersible granular (WDG) formulation
Charge all ingredients except active ingredients and safener in a pre-blender and mix them for 30 minutes. Start milling with air classifier mill (ACM). Collect powder in post blender, mix for 30 minutes. Transfer this powder in a dough mixer. Spray active ingredients and safener to the powder to get dough. Transfer dough to basket extruder by maintaining temperature of extruder below 70 0C. Start granulation with extruder. Dry granules at 70 0C. Subsequently, the sample were further tested for quality parameters for confirmation to the laid down specification and packed as per requirement after approval.
Table 3: Quantities of technical and raw materials charged
Component
CAS No. Function Quantities of raw material charged (Kg/100 kg batch)

Clodinafop-propargyl
(Purity 95.00% w/w) 105512-06-9 Active Ingredient 15.90
Cloquintocet-mexyl
(Purity 95.00% w/w) 99607-70-2 Safener 4.21
Carfentrazone-ethyl
(Purity 90.00% w/w) 128639-02-1 Active Ingredient 5.67
Lignosulfonate acid, sodium salt 8061-51-6 Wetting Agent 12.00
Alkyl polyglycoside 68515-73-1 Dispersing Agent 2.00
Precipitated silica 112926-00-8 Filler 5.00
China clay 1332-58-7 Filler 55.22
Process 2: Process of manufacturing of Clodinafop-propargyl and Carfentrazone-ethyl emulsifiable concentrate (EC) formulation
The required amounts of clodinafop-propargyl and carfentrazone-ethyl (Table 4) are transferred in mixing vessel with required quantity of safener, solvent, co-solvent, and dispersing agent and mix up to a clear homogeneous liquid. Now, add suitable emulsifiers in this clear homogeneous liquid and mix them. Add stabilizer to the clear homogeneous liquid and mix them. After dissolution and homogenization of emulsifier and stabilizer, filter the homogeneous liquid. Subsequently, the sample was further tested for quality parameters for confirmation to the laid down specification and packed as per requirement after approval.
Table 4: Quantities of technical and raw materials charged
Component
CAS No. Function Quantities of raw material charged (Kg/100 kg batch)

Clodinafop-propargyl
(Purity 95.00% w/w) 105512-06-9 Active Ingredient 15.90
Cloquintocet-mexyl
(Purity 95.00% w/w) 99607-70-2 Safener 6.32
Carfentrazone Ethyl
(Purity 90.00% w/w) 128639-02-1 Active Ingrdient 5.67
Mixture of anionic and non-ionic derivatives Not applicable Emulsifier 5.30
Tristyrylphenol ethoxylate 99734-09-5 Dispersing Agent 4.70
N-methyl-2-pyrrolidone 872-50-4 Co-solvent 5.00
Ethoxylated soybean oil 61791-23-9 Stabilizer 3.00
Solvent C-IX 64742 - 94 - 6 Solvent 54.11
Example 3
Method of evaluation of herbicidal composition.
Field tests of the compositions according to the present invention were conducted at various controlled trial sites. The performance of the herbicidal composition according to the present invention (Clodinafop-propargyl + Carfentrazone-ethyl) was compared against the known compositions of Clodinafop-propargyl 15% WP (TOPIC) and Carfentrazone-ethyl 40% DF (NABOOD), which were evaluated against weed spectrum in wheat crop and also the vigour/yield of the crop were tested. The wheat crop was sown in field and harvested after 128 days. Application was made using high volume knapsack sprayer at 25 days after sowing. Experimental design was in randomized blocks with four replication and each plot measured an area of 100 sq. m. (10 x 10 m). Observation on weed population, dry weight and weed control efficiency (WCE%) was assessed at 15; 30 and 45 days after application (DAA).
Table 5 below summarizes the synergistic effect that exists whenever the action of an active ingredient combination is greater than the sum of the actions of the individual components i.e. Clodinafop-propargyl and Carfentrazone-ethyl against different weed spectrum at different concentrations.
In the field of agriculture, it is often understood that the term "synergy" is as defined by Colby S. R. in an article entitled "Calculation of the synergistic and antagonistic responses of herbicide combinations" published in the journal Weeds, 1967, 15, p. 20-22. The action expected for a given combination of two active components can be calculated as follows:

Where,
E = Expected percentage of herbicidal control for the combination for the combination of the two herbicides at defined doses (for example equal to x and y respectively),
X = percentage of herbicidal control observed by the compound (I) at a defined dose (equal to x),
Y = percentage of herbicidal control observed by the compound (II) at a defined dose (equal to y),
When the percentage of herbicidal control observed for the combination is greater than the expected percentage, there is a synergistic effect.
Weed Control Efficiency
Using the total weed dry weight recorded at 45 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.

Weed control efficiency (%) =
(weed dry weight in untreated plot-weed dry weight in treated plot )/(weed dry weight in untreated plot) x100
For recording weed biomass (dry weight) in different herbicide treatments, a separate area of 0.5 x 0.5 m was marked in each plot and the weeds in each marked quadrant were removed at 45 days after herbicide spray and oven dried at 80? for 72 hours and weighed to estimate the dry weight of weeds. The weed dry weight was expressed in terms of g m-2 area.
Table 5: Synergistic impact of separate and combined treatments for narrow leaved (monocot) and broad leaved (dicot) weed spectrum at different concentrations of synergistic inseticidal composition Clodinafop-propargyl + Carfentrazone-ethyl.
Compound A.I./ha
WCE (%)at 45 DAA* Expected Control (Et) Colby’s Ratio (Ea+b/Et)
Clodinafop propargyl 45 Ea = 41.16 - -
Carfentrazone-ethyl 25 Eb = 48.27 - -
Clodinafop-propargyl + Carfentrazone-ethyl 45 + 25 Ea+b = 66.39 69.56 0.956
Clodinafop-propargyl 75 Ea = 56.09 - -
Carfentrazone-ethyl 15 Eb = 37.63 - -
Clodinafop-propargyl + Carfentrazone-ethyl 75 + 15 Ea+b = 75.81 72.61 1.044
Clodinafop-propargyl 60 Ea = 51.20 - -
Carfentrazone-ethyl 20 Eb = 47.91 - -
Clodinafop-propargyl + Carfentrazone-ethyl 60 + 20 Ea+b = 87.57 74.58 1.174
DAA = Days after application
Ea = % WCE after 45 DAA for Clodinafop-propargyl
Eb = % WCE after 45 DAA for Carfentrazone-ethyl
Ea+b = % WCE after 45 DAA for Clodinafop-propargyl + Carfentrazone-ethyl
Et = Expected %WCE after 45 DAA for Clodinafop-propargyl and Carfentrazone-ethyl in combination from alone
It can be seen from the data presented in Table 5, combination of Clodinafop-propargyl and Carfentrazone-ethyl demonstrate synergistic effect against different weed population.
Example 4: Bio-efficacy of synergistic herbicidal combination of Clodinafop-propargyl and Carfentrazone-ethyl against narrow leaved (monocot) and broad leaved (dicot) weed spectrum in wheat crop
Field tests of the compositions were conducted at various trial sites. The performance of the herbicidal composition according to the present invention (Clodinafop-propargyl + Carfentrazone-ethyl) was compared against the known compositions of Clodinafop-propargyl 15%; and Carfentrazone-ethyl 40% which were evaluated against narrow leaved (monocot) and broad leaved (dicot) weed spectrum and also the vigor/yield of the crop/straw was tested.
The wheat crop was sown in and harvested after 128 days. Application was made using spray method at 25 days after sowing. Experimental design was in randomized blocks with seven replication and each plot measured an area of 100 sq. m. (10 x 10 m). The formulations tested were weighed according to doses and diluted in water and applied using high volume knapsack sprayer and evaluated for % WCE in wheat. The reported results were mean of four replications of each evaluation designed in randomized complete blocks. The species-wise weed flora population/count (broad leaved and grassy weeds separately) was recorded before application of herbicide and also at at 15DAA (days after application), 30 DAA and 45 DAA after application of herbicides. For recording the weed population, an area of 0.5 x 0.5 m (0.25 m2) was marked at three spots in each treatment and weed observations were made from the same marked area and average was worked out and expressed in weed number per m2 area.
Details of Experiment
Target weeds: narrow leaved (monocot) and broad leaved (dicot) weeds
Crop: Wheat
Application Method: high volume knapsack sprayer fitted with flat fan nozzle
The treatment details are tabulated in Table 6 below.
Table 6: Treatment details for evaluation of Bio-efficacy of new herbicide against narrow leaved (monocot) and broad leaved (dicot) weed spectrum in Wheat
Particular Treatment Dose a.i./Acre Time of Application
T1 Clodinafop-propargyl + Carfentrazone-ethyl (20%) 18 + 6 g 25 DAS
T2 Clodinafop-propargyl + Carfentrazone-ethyl (20%) 24 + 8 g 25 DAS
T3 Clodinafop-propargyl + Carfentrazone-ethyl (20%) 30 + 10 g 25 DAS
T4 Clodinafop-propargyl 15% WP 24 g 25 DAS
T5 Clodinafop-propargyl 15% WP 30 g 25 DAS
T6 Carfentrazone-ethyl 40% DF 8 g 25 DAS
T7 Carfentrazone-ethyl 40% DF 10 g 25 DAS
T8 Hand Weeding @ 20 & 40 DAS -- --
T9 Control (No Treatment) -- --
The bio-efficacy effect of different treatment schedules on wheat crop and the treatment wise yield data of wheat crop is summarized in Table 7-11 below.
Table 7: Effect of new herbicide against narrow leaved (monocot) and broad leaved (dicot) weed spectrum (no./m2) in Wheat crop
S. No. Treatments Dose (g/acre) Weed Population (no./m2)
15 DAA* 30 DAA* 45 DAA*
Monocot Dicot Monocot Dicot Monocot Dicot
1 T1 120 g 12.40
(3.59) 7.60
(2.85) 10.30
(3.29) 7.50
(2.83) 11.60
(3.48) 8.90
(3.07)
2 T2 160 g 6.10
(2.57) 4.00
(2.12) 4.90
(2.32) 3.00
(1.87) 5.00
(2.35) 3.00
(1.87)
3 T3 200 g 5.60
(2.47) 3.90
(2.10) 4.70
(2.28) 3.00
(1.87) 4.50
(2.24) 2.80
(1.82)
4 T4 160 g 6.20
(2.59) 24.70
(5.02) 5.80
(2.51) 26.50
(5.20) 6.60
(2.66) 27.00
(5.24)
5 T5 200 g 5.90
(2.53) 23.80
(4.93) 5.20
(2.39) 26.00
(5.15) 5.40
(2.43) 25.40
(5.09)
6 T6 20 g 38.10
(6.21) 4.80
(2.30) 39.80
(6.35) 4.60
(2.26) 38.90
(6.28) 5.00
(2.35)
7 T7 25 g 37.00
(6.12) 4.30
(2.19) 37.20
(6.14) 3.40
(1.97) 38.00
(6.20) 4.80
(2.30)
8 T8 -- 3.20
(1.92) 2.80
(1.82) 16.80
(4.16) 11.30
(3.44) 18.10
(4.31) 15.20
(3.96)
9 T9 -- 41.40
(6.47) 25.60
(5.11) 43.20
(6.61) 26.70
(5.22) 44.00
(6.67) 27.30
(5.27)
DAA = Days after application
g = Gram
Values in parenthesis are square root transformed values
Data presented in table 7 shows that over all weed population was significantly affected by all the treatments against control when observed at 15, 30 and 45 days after application (DAA). At 45 DAA clodinafop-propargyl + carfentrazone-ethyl (20%) formulation @ 200 gm recorded lowest weed population comprising both narrow leaved (monocot) and broad leaved (dicot) weeds closely followed by clodinafop-propargyl + carfentrazone-ethyl (20%) formulation @ 160 gm. Similar, results were observed in Clodinafop-propargyl 15% WP @ 200 gm and

Table 8: Effect of herbicide against total weed dry weight/Biomass (g/m2) in Wheat crop
S. No. Treatments Dose (g/acre) Weed Dry Weight/Biomass (g/m2)
15 DAA* 30 DAA* 45 DAA*
Monocot Dicot Monocot Dicot Monocot Dicot
1 T1 120 g 18.64 9.37 17.73 10.20 19.68 12.39
2 T2 160 g 7.43 5.57 6.75 5.09 6.80 5.18
3 T3 200 g 6.73 4.51 6.37 4.31 6.48 3.90
4 T4 160 g 7.65 29.19 7.80 32.45 8.13 33.21
5 T5 200 g 6.98 28.81 7.03 30.96 7.83 32.04
6 T6 20 g 42.61 5.83 43.61 5.91 44.86 6.10
7 T7 25 g 41.27 5.52 42.18 5.06 42.87 5.68
8 T8 -- 4.50 3.67 17.26 12.06 26.43 22.18
9 T9 -- 48.29 32.09 48.72 38.18 53.61 40.49
SEm ± 0.05 0.05 0.04 0.03 0.03 0.02
CD5% 0.15 0.14 0.11 0.09 0.09 0.07
SEm+: Standard Error of Mean; CD @ 5%: Critical Difference
DAA = Days after application g = Gram
160 gm for narrow leaved (monocot) weeds, but as already stated no effect was seen against broad leaved (dicot) weeds. Similarly, in case of carfentrazone-ethyl 40% DF no/minimal effect was observed in narrow leaved (monocot) weeds. Data presented in table 8 and 9 further concludes that both the commercial formulations target only specific group of weeds and had minimal effect on over all weed control; whereas clodinafop-propargyl + carfentrazone-ethyl (20%) @ all the doses, significantly controls the overall weed problem comprising both narrow leaved (monocot) and broad leaved (dicot) weeds and thereby more efficacious as compared to available commercial formulation and also reduces the repeated/multiple application of the herbicides commonly practiced by the farmers. From the results presented in Table 7-9 and in table 10-11, it is evident that the application of clodinafop-propargyl + carfentrazone-ethyl (20%) @ all the doses significantly affects the yield attributes with more number of tiller/m2 and better grain and straw yield in compression to other treatments, with no phyto-toxicty at X, 1.25 X, 2 X and 2.5 X the recommended dose.
Table 9: Effect of Clodinafop-propargyl + Carfentrazone-ethyl (20%) (3:1) on the Weed Control Efficacy (WCE) (%) against narrow leaved (monocot) and broad leaved (dicot) weed spectrum in Wheat crop
S. No. Treatments Dose (g/acre) Weed Control Efficacy (WCE) (%)
15 DAA* 30 DAA* 45 DAA*
Monocot Dicot Monocot Dicot Monocot Dicot
1 T1 120 g 61.40 70.80 63.61 73.28 63.29 69.40
2 T2 160 g 84.61 82.64 86.15 86.67 87.32 87.21
3 T3 200 g 86.06 85.95 86.93 88.71 87.91 90.37
4 T4 160 g 84.16 9.04 83.99 15.01 84.83 17.98
5 T5 200 g 85.55 10.22 85.57 18.91 85.39 20.87
6 T6 20 g 11.76 81.83 10.49 84.52 16.32 84.93
7 T7 25 g 14.54 82.80 13.42 86.75 20.03 85.97
8 T8 -- 90.68 88.56 64.57 68.41 50.70 45.22
9 T9 -- - - - - - -
SEm ±
CD5%
SEm+: Standard Error of Mean; CD @ 5%: Critical Difference
DAA = Days after application g = Gram

It was surprisingly found that the percent weed control of narrow leaved (monocot) and broad leaved (dicot) weeds of wheat by clodinafop-propargyl + carfentrazone-ethyl (20%) (@160 g/Acre) is 87.32% and 87.21% was significantly at par with its higher dose (@ 200 g/Acre) and other market checks.
Clodinafop-propargyl + Carfentrazone-ethyl (20%) in the dose of 160 gm/acre also showed increased weed control at par with that of its higher dose for over all weed population of wheat than the single application of available market samples of both the actives.
Table 10: Effect of Clodinafop-propargyl + Carfentrazone-ethyl (20%) (3:1) herbicide on the Yield attributes in Wheat crop
S. No. Treatments Dose (g/acre) Yield Attributes
Plant Height (cm) Effective tiller (no./m2) Grain yield
(kg/ha) Straw yield
(kg/ha)
1 T1 120 g 77.18 76 3586 4862
2 T2 160 g 77.89 88 3935 5385
3 T3 200 g 76.20 89 4019 5342
4 T4 160 g 78.23 82 3626 4952
5 T5 200 g 77.01 84 3682 5012
6 T6 20 g 76.51 80 3561 4892
7 T7 25 g 79.86 82 3619 4937
8 T8 -- 77.68 84 3586 4906
9 T9 -- 76.24 68 3127 3766
SEM 5.87 0.02 20.82 44.59
CD5% NS 0.07 62.41 133.68

SEm+: Standard Error of Mean; CD @ 5%: Critical Difference
DAA = Days after application g = Gram
Highest grain and straw yield of wheat was recorded in treatment of Clodinafop-propargyl + Carfentrazone-ethyl (20%) in the dose of 200 gm/acre; i.e. 4019 and 5342 kg/ha respectively, which was statistically significant over all other treatments.
Table 11: Effect of Clodinafop-propargyl + Carfentrazone-ethyl (20%) (3:1) herbicide on the Phytotoxicity in Wheat crop
S. No. Treatments Dose (g/acre) Phytotoxicity (Days after Application)
1 DAA 3 DAA 7 DAA 14 DAA 21 DAA
1 Clodinafop- propargyl + Carfentrazone- ethyl (20%) 160 g 0 0 0 0 0
2 200 g 0 0 0 0 0
3 320 g 0 0 0 0 0
4 400 g 0 0 0 0 0
5 Control - 0 0 0 0 0
From the results in table 11, it is evident that the synergistic herbicidal composition of the present invention is non-phytotoxic in wheat crop.
It was thus concluded that Clodinafop-propargyl + Carfentrazone-ethyl (20%) at 160 mg/acre was the best combination dose over all other tested dose of Clodinafop- propargyl + Carfentrazone-ethyl to control both narrow leaved (monocot) and broad leaved (dicot) weeds of wheat and to obtain better yield attributes.
From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present investigation. It is to be understood that no limitations with respect to the specific embodiment 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.

CLAIMS:
1. A synergistic herbicidal composition comprising clodinafop-propargyl and carfentrazone-ethyl in a ratio of 5:1 to 1:2.
2. The synergistic herbicidal composition as claimed in claim 1, wherein clodinafop-propargyl and carfentrazone-ethyl are preferably in a ratio of 3:1.
3. The synergistic herbicidal composition as claimed in claim 1, wherein clodinafop-propargyl is present in an amount in the range from 5-50% w/w.
4. The synergistic herbicidal composition as claimed in claim 1, wherein carfentrazone-ethyl is present in an amount in the range from 1-10% w/w.
5. The synergistic herbicidal composition as claimed in any of the claims 1-4, wherein the composition is formulated as a water dispersible granule (WDG) or emulsifiable concentrate (EC).
6. The synergistic herbicidal composition as claimed in any of the claims 1-5, wherein the composition optionally comprises a safener, a wetting agent, a dispersing agent and a filler to form a water dispersible granule (WDG) formulation.
7. The synergistic herbicidal composition as claimed in claim 1-5, wherein the composition optionally comprises a safener, an emulsifier, a dispersing agent, a co-solvent, a stabilizer and a solvent to form the emulsifiable concentrate (EC) formulation.
8. The synergistic herbicidal composition as claimed in claims 1-7, wherein the composition is non-phytotoxic.
9. A method for controlling weeds, comprising treating the weeds with a composition comprising a synergistically effective amount of clodinafop-propargyl and carfentrazone-ethyl as claimed in claims 1-7.