DESC:FORM 2

THE PATENTS ACT 1970
(SECTION 39 OF 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(Section 10 and Rule 13)

NOVEL SYNERGISTIC HERBICIDAL COMPOSITION

We, COROMANDEL INTERNATIONAL LIMITED,
an Indian company incorporated under the Companies Act, 1956, and validly existing under the Companies Act, 2013. Having its registered office at Coromandel House, Sardar Patel Road,
Secunderabad – 500 003, Telangana, India

The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF THE INVENTION
The present invention relates to a novel synergistic herbicidal composition.

Particularly the present invention relates to a synergistic composition of propanil, bispyribac sodium and halosulfuron methyl in effective amounts along with adjuvants, and a process for preparation thereof.

More particularly, the present invention provides a method for controlling undesired plants or inhibiting their growth, which comprises applying a herbicidally effective amount of the said composition to the undesired plants or to a place where they grow.

BACKGROUND OF THE INVENTION
Herbicides, or chemical weed killers, have largely replaced mechanical methods of weed control in countries where intensive and highly mechanized agriculture is practiced. They provide a more effective and economical means of weed control than cultivation, hoeing, and hand pulling. Together with fertilizers, other pesticides, and improved plant varieties, they have made an important contribution to the increased yields we now have and serve to combat rising costs and shortages of agricultural labor.

They 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. The term true selectivity refers to the capacity of an herbicide, when applied at the proper dosage and time, to be active only against certain species of plants but not against others. But selectivity can also be achieved by placement, as when a nonselective herbicide is applied such that it reaches the weeds but not the crop.

Burndown, i.e., the complete removal of weeds from the soil by application of herbicides prior to planting or emergence of a crop, is an important tool of modern weed management. Weeds present at planting will generally grow much quicker than crop plants and thus compete very early in the growing season thereby damaging the crop plants and reducing crop yield. Thus, it is desirable to plant the crop in a weed-free seed bed or to assure that essentially no weeds are present when the crop emerges.

At present, many herbicidal compositions have been developed and used, but there are a variety of types of undesired plants represented by weeds to be controlled. Further, undesired plants having lowered sensitivity to herbicides (herbicide-resistant weeds) emerged, and in some applications, practically, herbicides have only insufficient effects. Hence, there is always a need for new active ingredients or new combinations of existing active ingredients to overcome the existing problems faced in the agricultural industry.

Compositions comprising a single herbicidally active component suffer from numerous drawbacks such as formation of resistant weeds, requirement of high amount and concentration of the active ingredient, environmental damage, seepage of the active component into ground water, phytotoxicity and harmful effects on the health of animals and humans.

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.

The synergistic herbicidal composition of the present invention can control a wide range of undesired plants emerging in agricultural fields or non-agricultural fields, and it shows a remarkable herbicidal activity.

Propanil is a highly selective postemergence herbicide that is used extensively to control barnyard grass (Echinochloa crus-galli) and jungle rice (Echinochloa colona) in several crops, especially rice. Propanil belongs to the class of anilides and is a photosynthetic inhibitor that inhibits the photosystem II (PS II) in chloroplasts.

Propanil is chemically known as N-(3,4-dichlorophenyl) propionamide, disclosed in Journal of Agricultural and Food Chemistry (1960), 8, 298-302 and has the following chemical structure.

Bispyribac-sodium is a new post-emergence pyrimidinyl carboxy herbicide for the control of a wide range of weeds, in specifically on Echinochloa crus-galli. Its mode of action consists of the inhibition of the branched amino acid biosynthesis and presents a good eco-toxicology profile.

Bispyribac-sodium is chemically known as Sodium-2,6-bis [(4,6-dimethoxy-2-pyrimidinyl) oxy] benzoate. It’s preparation and use are disclosed in US 4,906,285 and has the following chemical structure.

Halosulfuron methyl is a selective herbicide for post-emergence control of sedges and other weeds in sugarcane crops. It interferes with ALS enzyme, resulting in a rapid cessation of cell division and plant growth in both roots and shoots. The sulfonylurea herbicides are rapidly absorbed by the foliage as well as by the roots of plants. It is readily translocated throughout the plant and inhibits cell division. Decomposition of the sulfonylureas in the soil takes place by both hydrolytic and microbial processes. The rate of degradation is enhanced by increased temperatures, soil moisture content and low soil pH. Its adsorption to clay or soil colloids is relatively low.

Halosulfuron methyl is chemically known as methyl 3-chloro-5-[(4,6-dimethoxypyrimidin-2-yl) carbamoylsulfamoyl]-1-methylpyrazole-4-carboxylate. It’s preparation and use are disclosed in US 4,668,277 and has the following chemical structure:

The inventors of the present invention have surprisingly found that formulation of the three active components propanil, bispyribac sodium, and halosulfuron methyl has its own benefits such as it has lower application rate that not only reduces the amount of an active substance required for application, but as a rule, also reduces the amount of formulation auxiliaries required. Both reduce the economic outlay and improve the eco-friendliness of the herbicide treatment.

OBJECT OF THE INVENTION
It is an object of the present invention to provide a novel synergistic herbicidal composition of propanil, bispyribac sodium and halosulfuron methyl in effective amounts and adjuvants.

It is another object of the present invention to provide a process for the preparation of an herbicidal composition comprising of propanil, bispyribac sodium, and halosulfuron methyl.

It is yet another object of the present invention is to provide a method for controlling undesired plants or inhibiting their growth, which comprises applying a herbicidally effective amount of the said composition to the undesired plants or to a place where they grow.

SUMMARY OF THE INVENTION
The present invention provides a novel synergistic herbicidal composition comprising of propanil, bispyribac sodium and halosulfuron methyl in effective amounts and adjuvants.

In an embodiment, the herbicidal composition of the present invention comprises propanil in a range from 70% to 80% (w/w), bispyribac sodium in a range from 1% to 3% (w/w), and halosulfuron methyl in a range from 1% to 5% (w/w).

In an embodiment of the present invention, the adjuvants are selected from the group comprising wetting agents, dispersing agents, rheology modifiers and a fillers.

In an embodiment of the present invention, the wetting agent is selected from the group comprising sodium alkyl naphthalene sulphonate blend, dialkyl naphthalene sulphonate sodium salt, linear alcohol derivative and polyethylene glycol nonyl phenyl ether ammonium sulfate, present in a range from 5% to 10% (w/w).

In an embodiment of the present invention, the dispersing agent is selected from the group comprising sodium salt of methyl naphthalene sulfonate, sodium ligno sulphonate, acrylate copolymer, phenol sulfonic acid-formaldehyde-polycondensation as sodium salt, a mixture of salt of naphthalene sulphonic acid and phenol sulphonic acid condensation product, sodium poly alkyl naphthalene sulfonate, sodium polycarboxylate, sodium methyl oleoyl Taurate and sodium lauryl sulphate or combination thereof, present in a range from 5% to 10% (w/w).

In an embodiment of the present invention, the rheology modifier is silicon dioxide, present in an amount of 1% to 5% (w/w).

In an embodiment of the present invention, the filler is aluminum silicate (china clay), present in an amount of 2% to 6% (w/w).

In an embodiment of the present invention, the composition is formulated in a wettable powder (WP) form.

In another embodiment, the present invention provides a novel synergistic herbicidal formulation of propanil, bispyribac sodium and halosulfuron methyl with an improved stability and ready to use herbicidal composition, having superior bio-efficacy compared to the individual formulations.

In yet another embodiment, the present invention provides a method for controlling undesired plants or inhibiting their growth, which comprises applying a herbicidally effective amount of the said novel composition to the undesired plants or to a place where they grow.

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 term herbicide, as used herein, means an active ingredient that kills, controls or otherwise adversely modifies the growth of plants. Herbicidally effective or vegetation controlling amount is an amount of one or more active ingredient which causes an adversely modifying effect and includes deviations from natural development, killing, regulation, desiccation, retardation and the like. The terms plants, weeds and vegetation include germinant seeds, emerging seedlings, plants emerging from vegetative propagules and established vegetation.

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 and vegetation.

As used herein, the term “adjuvants(s)” refers to inert substances which are commonly used as diluent, to provide stability or to increase the activity profile of the composition or formulation with or without having agrochemical activity or direct effect on the undesired weeds.

Unless otherwise specified, % refers to % weight; and % weight refers to % of the weight of the respective component with respect to the total weight of the composition.

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.

In one aspect, the present invention provides a novel synergistic herbicidal combination of propanil, bispyribac sodium, and halosulfuron methyl in effective amounts with adjuvants.

In another aspect, the present invention provides a method for controlling undesirable vegetation in crops, which comprises applying a combination as defined herein to a locus of planted crops where undesirable vegetation occurs or might occur or to a locus where crops will be planted before planting or emergence of the crop.

In another aspect, the present invention provides a weed controlling activity, the said composition comprising herbicidally effective amounts of a combination of propanil, bispyribac sodium and halosulfuron methyl has the potential of controlling the cross-spectrum weeds (broad leaf weeds, grassy weeds, and sedges) in rice. All three molecules are safe to transplant and direct seeded rice when applied in post-emergence (15-20 days after transplanting) application timing.

Accordingly, the inventors of the present invention have formulated a synergistic herbicidal composition, comprising: propanil, bispyribac sodium, halosulfuron methyl and adjuvants; wherein propanilin a range from 70% to 80% (w/w), bispyribac sodium in a range from 1% to 3% (w/w), halosulfuron methyl in a range from 1% to 5% (w/w).

The synergistic herbicidal composition of the present invention may be formulated as Water dispersible granules (WG or WDG), Wettable powder (WP), Water dispersible powder for slurry seed treatment (WS), Water dispersible tablet (WT), Dispersible concentrate (DC), Dustable powder (DP), Powder for dry seed treatment (DS), Granules (GR), Water soluble granule (SG), 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), 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), Soluble concentrate (SL), Spreading oil (SO), Water soluble powder (SP), Water soluble tablet (ST), Ultra-low volume (ULV) Tablet (TB), 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 formulated as a wettable powder (WP).

Preferably, the synergistic herbicidal composition is in the form of a wettable powder and the adjuvants are selected from the group comprising a wetting agent, a dispersing agent, a rheology modifier, 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 preferably contains a wetting agent such as sodium alkyl naphthalene sulphonate blend, dialkyl naphthalene sulphonate sodium salt, linear alcohol derivative and polyethylene glycol nonyl phenyl ether ammonium sulfate. Wetting agent is present in a range from 5% to 10% (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 preferably contains a dispersing agent such as sodium salt of methyl naphthalene sulfonate, sodium ligno sulphonate, acrylate copolymer, phenol sulfonic acid-formaldehyde-polycondensation as sodium salt, a mixture of salt of naphthalene sulphonic acid and phenol sulphonic acid condensation product, sodium poly alkyl naphthalene sulfonate, sodium polycarboxylate, sodium methyl oleoyl Taurate and sodium lauryl sulphate or combination thereof. A dispersing agent is present in a range from 5% to 10% (w/w).

A “rheology modifiers” are designed to bring superior structuring to formulations, allowing to control the viscosity and are easy to use and provide better stability, and suspensibility performance. A rheological modifier suitable for use in the present invention is silicon dioxide present in a range from 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. The filler suitable for use in the present invention is aluminum silicate, present in a range from 2% to 6% (w/w).

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

Herbicides or combination of herbicides can be applied in different ways, for example, sequential application, tank-mix application, and premix application. In sequential application, farmers use different herbicides, wherein the herbicide selection is often not based on the technical know-how. Consequently, herbicides having the same mode of action contribute to resistance development. In tank-mix applications, farmers use different combinations of herbicides, most of the time without having the training to properly mix appropriate products. Homemade tank mixes may therefore not be as stable as a premix. In such cases, the tank-mix application usually results in non-judicious use of individual herbicides and ends up with poor weed control. Moreover, the tank mixture is less convenient and potentially hazardous to people who are not trained to properly mix the products.

The 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 cereals, such as wheat, barley, rye, oats, corn/maize, rice, sorghum, triticale and related crops; fruit, such as pomes, stone fruit and soft fruit, for example apples, grapes, pears, plums, peaches, almonds, cherries, and berries, for example strawberries, raspberries and blackberries; leguminous plants, for examples beans, lentils, peas, soybeans, peanut; oil plants, for example rape, mustard, and sunflower; cucurbitaceae, for example marrows, cucumbers, melons; fibre plants, for example cotton, flax, hemp, jute; citrus fruit, for example oranges, lemons, grapefruit and mandarins; vegetable, for example spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, paparika; as well as ornamentals, such as flowers, shrubs, broad-leaved trees and evergreens, for example conifers, pastures, grasslands, rangelands, fallow and, turf, tree and vine orchards, 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. It has been surprisingly found that the novel herbicidal composition of the present invention delays the appearance of the resistant strains of weeds and achieves effective and economical control of undesired weeds.

The 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 labor cost, saving in applicator’s time and loss caused by mechanical damage to the crop and soil.

The present 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 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 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.

PROCEEDURE:

Preparation of composition of propanil, bispyribac sodium, and halosulfuron methyl in a wettable powder (WP) form:
Step 1: weighing the raw materials according to the batch size as follows:
a. filler,
b. wetting agent,
c. dispersing agents,
d. rheology modifier,
e. propanil,
f. bispyribac sodium, and
g. halosulfuron methyl.
weighing all this raw material in a pre-blender and mixing it for 1 hour,
Step 2: Milling the sample through air jet mill instrument at Inlet pressure 2-3 kg/cm2, grinding pressure 6 kg/ cm2, and checking the particle size < 15 microns,
Step 3: Collecting the milled material, and post blending the sample for 1 hour,
Step 4: Sending the sample to the quality analysis,
Step 5: Packing the formulated material in suitable packaging.

Examples: Formulation of propanil 75%, bispyribac sodium 1.5%, and halosulfuron methyl 3% in a wettable powder (WP) form:

The illustrative embodiments show the composition of propanil, bispyribac sodium, and halosulfuron methyl in a wettable powder form in different amount as shown in Table 1 to 5 following the process given above.

Table-1: Propanil 75% + Bispyribac sodium 1.5% + Halosulfuron methyl 3% (WP):

S. No. Ingredients Function Quantity (in %w/w)
1. Propanil @98% Active ingredient 75.0
2. Bispyribac sodium @ 95% Active ingredient 1.5
3. Halosulfuron Methyl @98% Active ingredient 3.0
4. sodium alkyl naphthalene sulphonate blend Wetting agent 6.0
5. A mixture of salt of naphthalene sulphonic acid and phenol sulphonic acid condensation product. Dispersing agent 6.0
6. Sodium poly alkyl naphthalene sulphonate Dispersing agent 2.0
7. Silicon dioxide Rheology modifier 1.0
8. Aluminum silicate (china clay) Filler 5.5
Total 100

Table-2: Propanil 75% + Bispyribac sodium 1.5% + Halosulfuron methyl 3% (WP):
S. No. Ingredients Function Quantity (in %w/w)
1. Propanil @98% Active ingredient 75.0
2. Bispyribac sodium @95% Active ingredient 1.5
3. Halosulfuron Methyl @98% Active ingredient 3.0
4. sodium alkylnaphthalene sulphonate blend Wetting agent 5.0
5. phenol sulfonic acid-formaldehyde-polycondensation as sodium salt Dispersing agent 5.0
6. Acrylate copolymer Dispersing agent 4.0
7. Silicon dioxide Rheology modifier 1.0
8. Aluminum silicate (china clay) Filler 5.5
Total 100

Table-3: Propanil 75% + Bispyribac sodium 1.5% + Halosulfuron methyl 3% (WP):
S. No. Ingredients Function Quantity (in %w/w)
1. Propanil @98% Active ingredient 75.0
2. Bispyribac sodium @ 95% Active ingredient 1.5
3. Halosulfuron Methyl @98% Active ingredient 3.0
4. Dialkyl naphthalene sulphonate sodium salt Wetting agent 6.0
5. Sodium salt of methyl naphthalene sulfonate Dispersing agent 6.0
6. phenol sulfonic acid-formaldehyde-polycondensation as sodium salt Dispersing agent 3.0
7. Silicon dioxide Rheology modifier 1.0
8. Aluminum silicate (china clay) Filler 4.5
Total 100

Table-4: Propanil 75% + Bispyribac sodium 1.5% + Halosulfuron methyl 3% (WP):
S. No. Ingredients Function Quantity (in %w/w)
1. Propanil @98% Active ingredient 75.0
2. Bispyribac sodium @ 95% Active ingredient 1.5
3. Halosulfuron Methyl @98% Active ingredient 3.0
4. Linear Alcohol Derivative Wetting agent 6.0
5. Sodium polycarboxylate Dispersing agent 6.0
6. Sodium Methyl Oleoyl Taurate Dispersing agent 3.0
7. Silicon dioxide Rheology modifier 1.0
8. Aluminum silicate (china clay) Filler 4.5
Total 100

Table-5: Propanil 75% + Bispyribac sodium 1.5% + Halosulfuron methyl 3% (WP):
S. No. Ingredients Function Quantity (in %w/w)
1. Propanil @98% Active ingredient 75.0
2. Bispyribac sodium @ 95% Active ingredient 1.5
3. Halosulfuron Methyl @98% Active ingredient 3.0
4. Polyethylene glycol Nonylphenol ether ammonium sulfate Wetting agent 6.0
5. Sodium Ligno sulphonate Dispersing agent 6.0
6. Sodium lauryl sulphate Dispersing agent 3.0
7. Silicon dioxide Rheology modifier 3.0
8. Aluminum silicate (china clay) Filler 2.5
Total 100

Efficacy study for combination of propanil 75%, bispyribac sodium 1.5%, and halosulfuron methyl 3% (WP):

FIELD AND SYNERGY STUDIES
Weeds were reported to reduce rice yields by 12 to 98%, depending on type method of rice establishment. Rice yield losses due to uncontrolled weed growth and weed competition were least (12%) in transplanted rice and highest in aerobic direct-seeded rice. Traditionally, weed control in India has been largely dependent on manual weeding. However, increased labour scarcity and costs are encouraging farmers to adopt herbicides.

The field studies were conducted to compare the weed controlling activity of the combination of Propanil, Bispyribac sodium & Halosulfuron methyl. The active ingredient, Propanil belongs to chemical family “Amides” with mode of action PS-II inhibitors (inhibition of Photosystem II), Bispyribac sodium & Halosulfuron methyl belongs to chemical family “Pyrimidinyl benzoates” & “Sulfonylurea” respectively having ALS (inhibition of acetolactate synthase) mode of action. The combination has the potential of controlling the cross-spectrum weeds (broad leaf weeds, grassy weeds, and sedges) in rice. All three molecules are safe to transplant & direct seeded rice when applied in post-emergence (15-20 days after transplanting) application timing.

The weed control activity of the individual herbicides of the invention and their combinations were evaluated on weeds such as Cyperus difformis, Cyperus iria, Echinochloa colonum, Echinochloa crusgalli, Monochoria vaginalis, Ludwigia parviflora & Eclipta alba. Trials were conducted with randomized block design with net plot size of 5m x 6m. Each trial was replicated four times and conducted under GEP guidelines. Spraying was done with manual operated backpack knapsack sprayer with 375 L of water spray volume per hectare at post-emergence (15-20 days after transplanting) 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 21 days after application. These observations are to be taken from the 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 the 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) ***

Three-way combination:
(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.

Two-way combination:

If A1 = the percent inhibition of growth by herbicide A at given rate
B1 = the percent inhibition of growth by herbicide B at given rate then,
B1 (100 – A1)
E = A1 +
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.
C = observed efficacy of active ingredient C at the same concentration as used in the mixture.

When the percentage of pesticidal 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 tables:

Table 6: Demonstrates synergy on weeds using the combination of Propanil, Bispyribac sodium and Halosulfuron methyl with their two-way and three-way combinations. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 21 days of application. The target weeds were Cyperus iria and Cyperus difformis and the results are recorded in the below table.

Active Dose (GAH) % Weed Control of Cyperus iria % Weed Control of Cyperus difformis
Expected Observed Expected Observed
Propanil 80% DF 1500 -- 50 -- 40
Bispyribac sodium 10% SC 30 -- 75 -- 65
Halosulfuron methyl 75% WDG 60 -- 70 -- 70
Propanil 80% DF + Bispyribac sodium 10% SC 1500 + 30 87.5 85 79 75
Ratio of O/E 0.97 0.94
Bispyribac sodium 10% SC + Halosulfuron methyl 75% WDG 30 + 60 92.5 90 89.5 85
Ratio of O/E 0.97 0.94
Propanil 80% DF + Halosulfuron methyl 75% WDG 1500 + 60 85 80 82 80
Ratio of O/E 0.94 0.97
Bispyribac sodium 1.5% + Propanil 75% + Halosulfuron methyl 3% WP 30 +1500 + 60 96.25 100 93.7 95
Ratio of O/E 1.03 1.01
WP – Wettable powder; DF – Dry flow; WDG – Water dispersible granules; SC – Suspension concentrate; and GAH – Gram active per hectare.

The results in table 6 clearly demonstrate synergy between 3-way combination of Propanil, Bispyribac sodium and Halosulfuron methyl against weeds like, Cyperus iria and Cyperus difformis. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination. However, all 2-way combinations showed lower ratio of the observed and the expected efficacy, which clearly showed the no synergistic effect of the combination against weeds like Cyperus iria and Cyperus difformis.

Table 7: Demonstrates synergy on weeds using the combination of Propanil, Bispyribac sodium and Halosulfuron methyl with their two-way and three-way combinations. The percentage efficacy was calculated after 21 days of application. The target weeds were Echinochloa colonum, Echinochloa colonum and Leptochloa chinensis. The results are recorded in the below table.

Active Dose (GAH) % Weed Control of Echinochloa colonum % Weed Control of Echinochloa crusgalli % Weed Control of Leptochloa chinensis
Expected Observed Expected Observed Expected Observed
Propanil 80% DF 1500 -- 50 -- 40 -- 45
Bispyribac sodium 10% SC 30 -- 70 -- 60 -- 20
Halosulfuron methyl 75% WDG 60 -- 5 -- 10 -- 0
Propanil 80% DF + Bispyribac sodium 10% SC 1500 + 30 85 82 76 75 56 50
Ratio of O/E 0.96 0.98 0.89
Bispyribac sodium 10% SC + Halosulfuron methyl 75% WDG 30 + 60 71.5 70 64 60 20 20
Ratio of O/E 0.97 0.93 1.00
Propanil 80% DF + Halosulfuron methyl 75% WDG 1500 + 60 52.5 50 46 45 45 45
Ratio of O/E 0.95 0.97 1.00
Bispyribac sodium 1.5% + Propanil 75% + Halosulfuron methyl 3% WP 30 +1500 + 60 85.75 90 78.4 80 56 60
Ratio of O/E 1.04 1.02 1.07
WP – Wettable powder; DF – Dry flow; WDG – Water dispersible granules; SC – Suspension concentrate; and GAH – Gram active per hectare.

The results in table 7 clearly demonstrate synergy between a three-way combination of Propanil, Bispyribac sodium and Halosulfuron methyl against weeds like Echinochloa colonum, Echinochloa colonum and Leptochloa chinensis. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination. However, all two-way combinations showed lower ratio of the observed and the expected efficacy, which clearly showed the no synergistic effect of the combination against weeds like, Echinochloa colonum, Echinochloa colonum and Leptochloa chinensis.

Table 8: Demonstrates synergy on weeds using the combination Propanil, Bispyribac sodium and Halosulfuron methyl with their two-way and three-way combinations. The field trials were carried out in India at various locations. The percentage efficacy was calculated after 21 days of application. The target weeds were Monochoria vaginalis, Ludwigia parviflora and Eclipta alba. The results are recorded in the below table.

Active Dose (GAH) % Weed Control of Monochoria vaginalis % Weed Control of Ludwigia parviflora % Weed Control of Eclipta alba
Expected Observed Expected Observed Expected Observed
Propanil 80% DF 1500 30 50 60
Bispyribac sodium 10% SC 30 70 75 70
Halosulfuron methyl 75% WDG 60 20 10 10
Propanil 80% DF + Bispyribac sodium 10% SC 1500 + 30 79 75 87.5 85 88 85
Ratio of O/E 0.94 0.97 0.96
Bispyribac sodium 10% SC + Halosulfuron methyl 75% WDG 30 + 60 76 75 77.5 75 73 70
Ratio of O/E 0.98 0.96 0.95
Propanil 80% DF + Halosulfuron methyl 75% WDG 1500 + 60 44 40 55 55 64 60
Ratio of O/E 0.90 1.00 0.93
Bispyribac sodium 1.5% + Propanil 75% + Halosulfuron methyl 3% WP 30 +1500 + 60 83.2 85 88.75 90 89.2 95
Ratio of O/E 1.02 1.01 1.06
WP – Wettable powder; DF – Dry flow; WDG – Water dispersible granules; SC – Suspension concentrate; and GAH – Gram active per hectare.

The results in table 8 clearly demonstrate synergy between a three-way combination of Propanil, Bispyribac sodium and Halosulfuron methyl against weeds like Monochoria vaginalis, Ludwigia parviflora and Eclipta alba. The higher ratio of the observed and the expected efficacy clearly demonstrates the synergistic effect of the combination. However, all two-way combinations showed lower ratio of the observed and the expected efficacy, which clearly showed the no synergistic effect of the combination against weeds like, Monochoria vaginalis, Ludwigia parviflora and Eclipta alba.

Although the present invention has been described and illustrated with respect to preferred embodiments and a preferred use thereof, it is not to be so limited since modifications and changes can be made therein which are within the full scope of the invention. ,CLAIMS:We claim:
1. A synergistic herbicidal composition comprising a combination of propanil, bispyribac sodium, and halosulfuron methyl in effective amounts and adjuvants.

2. The composition as claimed in claim 1, wherein propanil is present in a range from 70% to 80% (w/w), bispyribac sodium is present in a range from 1% to 3% (w/w), and halosulfuron methyl is present in a range from 1% to 5% (w/w).

3. The composition as claimed in claim 1, wherein the adjuvants are selected from the group comprising a wetting agent, a dispersing agent, a rheology modifier, and a filler.

4. The composition as claimed in claim 1, wherein the wetting agent is selected from the group comprising sodium alkyl naphthalene sulfonate blend, dialkyl naphthalene sulphonate sodium salt, linear alcohol derivative and polyethylene glycol nonyl phenyl ether ammonium sulfate, present in a range from 5% to 10% (w/w).

5. The composition as claimed in claim 3, wherein the dispersing agent is selected from the group comprising sodium salt of methyl naphthalene sulfonate, sodium ligno sulphonate, acrylate copolymer, phenol sulfonic acid-formaldehyde-polycondensation as sodium salt, a mixture of salt of naphthalene sulphonic acid and phenol sulphonic acid condensation product, sodium poly alkyl naphthalene sulfonate, sodium polycarboxylate, sodium methyl oleoyl taurate and sodium lauryl sulphate or combination thereof, present in a range from 5% to 10% (w/w).

6. The composition as claimed in claim 3, wherein the rheology modifier is silicon dioxide, present in an amount of 1% to 5% (w/w).

7. The composition as claimed in claim 3, wherein the filler is aluminum silicate, present in an amount of 2% to 6% (w/w).

8. The composition as claimed in claim 1, wherein the composition is formulated as wettable powder form.

9. The composition as claimed in claim 1, is used for controlling weeds.

Dated this Eighteenth (18th) day of August, 2023

_____________________________
Dr. S. Padmaja
Agent for the Applicant
IN/PA/883