FIELD OF INVENTION
The invention relates to an herbicidal combination for effective control of weeds more specifically in rice crop.
BACKGROUND OF THE INVENTION
The use of herbicide combinations is a widespread and documented practice in the agricultural community. Herbicidal combinations offer significant advantages over individual applications including improved and extended weed control, reduced herbicide rates and application costs, shorter contact times for improved results in flowing water, less stringent use restrictions, improved selectivity, improved spectrum of weeds controlled, reduced cost and reduced residue problems. However, identifying appropriate herbicide application rates and combinations is essential to achieve synergistic weed control.

In recent times the trend of growing resistance to all kinds of Herbicides, control of multiple weeds of different types on same host, formation of residues are great concern and utmost challenge to the scientist community as a whole. With rapid urbanization there is a constant erosion of farming land and at the same time increasing population has created a growing demand of farm products r cultivations of crops which favours numerous weeds attack on crop plant.

The diversity of weeds and their potential for causing serious loss of crop yield in combination or singly has resulted in the need for broad-spectrum weeds control. There are numerous chemical compounds (Herbicides), which aid in preventing weeds of plants, however most of them have practical deficiencies, which restricts their applicatfori. The inability of any one Herbicide to control Sill of th"^ potehtially sertous-weeds on one-crop makes the use of combinations or mixtures of Herbicides a part of normal control practice. Further, continuous uses of Herbicide, which has one way

mode of action, always lead the resistance development in target weed. This is one of the many sufferings of the prior art.

OBJECTIVES OF THE INVENTION
The main objective of this invention is to use a combination or mixture of the herbicide which has different mode of action on target weed and can prevent resistance development in harmful weeds.

The other main objective of this invention is to provide a broad spectrum herbicidal composition. Another objective of the present invention is to provide a synergistic Herbicide combination, the bio-efficacy of which is superior to the mixture of the individual formulations at reduced rate of application of individual active in combination which will prevent accumulations of residue in plant and its harvests. Another objective of the present invention is to provide an improved, stable and ready to use herbicidal composition effective against a wide spectrum control of annual and perennial broad-leaved weeds and sedges, pre- or post-emergence, in wet-sown and transplanted rice crops. Another objective of the present inventions is to prevent resistant development in weeds, more particularly in Cereals crop like rice.
Pyrazosulfuron ethyl is a new rice herbicide belong in the sulfonylurea group, it has eminent activity against a broad spectrum of annual and perennial rice paddy weeds, especially broad leaf weeds and sedges, with pre-emergence and early post-emergence application and at extremely low use rates. The activity of this compound is good at higher application dose which some time led the accumulation of residue resulted harmful for human consumptions; however, at lower application dose, and only take care of broad leaves weeds.

Bispyribac sodium Effective control over grasses, sedges and broad leaved weeds infesting rice fields in nursery and main field Excellent rice crop selectivity. Flexibility in application time It has wide application window and can be used in early post emergent segment compatible with other plant protection chemicals including Carbamates and Organo-phosphate Pesticide without any adverse effect in rice.

Still further objective of the invention to load less actives and more efficacy in a single formulation.
Still further objective is to check out the physical compatibility of the actives.
Still further objective is to check out the chemical compatibility of the actives.
Still further objective is to select the type of formulation for such a combination of actives for optimum result and process development.
Still further objective is to develop the stable recipe of the actives.
Still further objective is to make eco-friendly Formulation.
Still further objective to make user friendly Formulation.

SUMMARY OF THE INVENTION
One possibility for overcoming such difficulties is to alternate the active compounds used, so that the development of resistance can be prevented or atleast slowed down. However, this requires the continual development of new active compounds, so as to avoid selection to the particular mechanism of action.

In contrast, it is more sensible to be able to employ combination which has proven sufficiently effective and able to control multiple weeds for as long as possible, especially when it has shown itself to be environmentally compatible to a particularly high degree and to possess only minimal side-effects.

Pyrazosulfuron ethyl is a new rice herbicide belong in the sulfonylurea group. It has eminent activity against a broad spectrum of annual and perennial rice paddy weeds, especially broad leaf weeds and sedges, with pre-emergence and early post-emergence application and at extremely low use rates The activity of this compound is good at higher application dose which some time led the accumulation of residue resulted harmful for human consumptions; however, at lower application dose, it is sometimes unsatisfactory to control the weeds and only take care of broad leaves weeds.

Bispyribac-sodium — good watergrass herbicide that can be useful to suppress herbicide-resistant forms of these weeds. It is a post emergence herbicide that is also effective on barnyardgrass and moderately active on rice field bulrush. However, it is an ALS inhibitor and resistant watergrass biotypes have been detected. Repeated use on the same area must be avoided.

Efficacy of the combination formulations in present invention are depends upon the use of proper quantities of ingredients of individual active. There are practical problems in dispensing exact quantities of the individual herbicidal formulation as tank mix by the farmer in the field. Use of the higher quantities of the individual Herbicide then recommended dose can result in phyto-toxicity, accumulation of residue in plant as well as lead wastage and hence higher cost. There are also possibilities of using Herbicides with lower dose than recommended dosage, which can lead to fast resistance, insufficient weed control and crop yield loss.

Therefore, considering the importance of effective control of a wide spectrum of weeds like Post-emergence, annual and perennial weeds., simultaneously need for an herbicidal composition which is stable, synergistic, broad spectrum, eco-friendly, and ready to use and less expensive was felt.

DESCRIPTION OF THE INVENTION
The present invention relates to herbicidal mixtures for controllingof wide range weeds specially Echinocloa sp., stunt the growth of weeds in non-crop situation, annual, perennial broad leaves weeds, sedges, pre or post-emergence in wet sown and transplanted rice crops.
1. The Pyrazosulfuron ethyl of the formula I and
2. Bispyribac sodium of the formula II,

The following specification describes the invention and discloses a synergistic herbicidal combination comprising pyrazosulfuron ethyl and Bispyribac Sodium which are at weight ratio of 1:5-5:4 molar ratio of first active ingredient to the second active ingredient, more preferably in the ratio of 181:221. The synergistic effect of the pesticide combination can be prepared to Water dispersible powder and water dispersible granules. Compared with the existing single preparation, the combination not only has obvious herbicidal effect but also has excellent synergistic effect & reduces the development of resistance, has less amount of residue and causes less contamination to the crops, so the combination is safe & environment friendly. The active compound combinations according to the invention have very good herbicidal properties and can be employed for controlling 5f wide range weeds specially Echinocloa sp., stunt the growth of weeds in non-crop situation, annual, perennial broad leaves weeds, sedges, pre or post-emergence in wet sown and transplanted rice crops.
In a synergistically effective amount. Moreover, the invention relates to a method for
controllingof wide range weeds specially Echinocloa sp.t stunt the growth of weeds in
non-crop situation, annual, perennial broad leaves weeds, sedges, pre or post-
emergence in wet sow^ a^^^ using mixtures of the compound I
with the compound II preparing such mixtures and compositions comprising these
mixtures.

(a) Pyrazosulfuron ethyl in the range of 1 to 20% of the total mass of the composition.
(b) Bispyribac sodium in the range of 1 to 40 % of the total mass of the composition.
(c) Atleast one wetting agent with 0.5 to 5 % of total mass of the composition.
(d) Atleast one dispersing agent with 0.5 to 6 % of the total mass of the composition.
(e) Atleast one De-foamer with 0.1 to 1.0 %of the total mass of the composition.
(f) Optionally Filler with 10 to 55% of the mass of the composition.

In preferred embodiment of the present invention, pyrazosulfuron ethyl is preferably in the range of 1 to 20% of the total mass of the composition.

In preferred embodiment of the present invention, Bispyribac sodium is preferably in the range of 1to 40%of the total mass of the composition.

Typically, the wetting agent is atleast one compound selected from a group of compounds consisting of alcohol alkylate ,fatty alcohol ethoxylates, alkyl naphthalene sulfonate, sodium lauryl sulphates, sodium dodecyl benzene sulfonate and sodium dialkylnaphthalenesulfonate, blend of Polymeric Surfactants. Typically, the Dispersing agent is atleast one compound selected from a group of compounds consisting of sodium lignosulfonate, calcium lignosulfonate, sodium salt of alkyl naphthalene sulfonate condensate, Lignosulfonic acid, sodium salt suIfomethylated, sulfonated aromatic polymer, sodium salt; alcohol ethoxylates and fatty alcohol ethoxylates, blends of polymeric surfactants.

Typically, the filler used is atleast one compound or multiple selected from China Clay, Precipitated Silica, Lactose-Monohydrate, Lactose Anhydrous, Starch of different grades & origin, Ammonium Sulphate, Sodium Sulphate, Magnesium Sulphate, Attapulgite Clay, talc. Typically, the WDG composition has two actives, which can be formulated asWP, WDG. Typically, the Water DisperSibte Granules (WDG) has a solid pesticide micronized to powder through air jet milling and extruded from basket-extruder, In accordance with another aspect of the present invention there is provided a

process for preparing a synergistic herbicidal composition, said process comprising the following steps:
a) Blending atleast Technical Herbicide selected from the group consisting of Bispyribac Sodium and Pyrazosulfuron ethyl, with atleast one surfactant selected from the group consisting of wetting agents, Dispersing agents, anti-foaming agent, and fillers to obtain homo'geri©us riiixture

b) Grinding the mixture by atleast one process selected from the group consisting of pulverizing and Air Jet milling, to obtain a grinded mixture; and get the pulverised homogenous wettable Powder. This can be tested for all in accordance with FAO guidelines.

Typically, in step b) the mixture is make wet by water to obtain dough having a moisture atleast in the range of 5 -20 % by total composition.

In accordance with the preferred embodiment of the process of the present invention, the ^Jough is atleast extrucleci, spray dried, or granulise^ by Pan-granuiatot to get the stable formulation.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 illustrates a synergistic herbicidal composition of Pyrozosulfuron ethyl and Bispyribac sodium WP formulating using Air-jet- Mill labmodel equipment.

Figure 2 illustrates a synergistic herbicidal composition of Pyrozosulfuron ethyl and Bispyribac sodium WDG formulating using Air-jet- Mill labmodel equipment.

DETAILED DESCRIPTION OF THE INVENTION:

Herbicides: I
IUPAC NAME: ethyl 5-(4, 6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-
methylpyrazole-4-carboxylate.
CAS Number: [98389-04-9]
Molecular weight: 414.4
Molecular formula: CuHieNeOyS Molecular Structure:
Form: Colorless crystals
MP. 177.8-179.5 °C V.p. 4.2 x lO"5mPa (25 °C) Kow logP = 3.16 (hplc method) S.g./density 1.46 (20 °C) Solubility In water 9.76 mg/l (20 °C). In methanol 4.32, hexane 0.0185, benzene 15.6, chloroform 200, acetone 33.7 (all in g/l, 20 °C). Stability Stable at 50 °C for 6 months. Relatively stable at pH 7. Unstable in acidic or alkaline media. pKa 3.7

Biochemistry Branched chain amino acid synthesis (ALS or AHAS) inhibitor. Acts by inhibiting biosynthesis of the essential amino acids valine and isoleucine, hence stopping cell division and plant growth. Selectivity derives from rapid metabolism (demethylation of methoxy group) in the crop. Metabolic basis of selectivity in sulfonylureas reviewed (M. K. Koeppe& H. M. Brown, Agro-Food-lndustry, 1995, 6, 9-14).

Mode of action Systemic herbicide, absorbed by roots and/or leaves and trah'srocated to the rheristertis.

Uses Control of annual and perennial broad-leaved weeds and sedges, pre- or
post-emergence, in wet-sown and transplanted rice crops, at 15-30 g/ha.
Herbicides: II
IUPAC Name: Sodium 2, 6-bis (4, 6-dimethoxypyrimidin-2-yloxy) benzoate
CAS Number: [125401-75-4]acid; [125401-92-5]sodium salt
Molecular weight: 452.4
Molecular formula: CigHi/N^NaOs

Molecular Structure:
Form White odourless powder. MP. 223-224 °C V.P. 5.05 x 10"6mPa (25 °C) KowJogP = -1.03 (23 °C) Henry 3 x 1a11 Pa m3 mol"1 (calc.) S.gr./density 1.47 Solubility in water 68.7 g/l (20 °C, distilled water). In methanol 25 g/l (20 °C); in ethyl acetate 6.1 x 10~2, n-hexane 8.34 x 10~3, acetone 1.4, toluene <1.0 x 10~6, dichloromethane 1.3 (all in mg/l, 25 °C). Stability Decomposes at 223 °C. Hydrolysis DTsn>1 y (£H 7 and 9, 25 °C), 88 d (pH 4, 25 °C).Aqueous photolysis DTgn 42 d in natural water, 499 d in distilled water (both 25 °C, 1.53 W/m2, 260-365 nm).pKa3.35 (20 °C).Uses: Early post-emergence control of broad-leaved weeds in rice crop.

This invention relates to an herbicidal composition containing a combination of Herbicides such as Pyrazosulfuron ethyl and bispyribac sddium Which mutually affect . each other when used together and display a biological activity greater than the sum of the activities when used alone. They target both the types of the weeds occurs in rice crop etc.

In the course of our studies of Herbicides we have found, that the combination of Pyrazosulfuron ethyl and Bispyribac Sodium, results in a synergistic mixture which is remarkably more effective than the individual compounds at the considered doses

The weight ratio of the components A and B depends on the sensitivity and resistance of the plants, the time of application, the climatic conditions and the soil conditions.

The synergistic composition of the present invention is prepared by initially mixing one of the active ingredients with wetting agent / Dispersing agent / filler in a vessel. The mixture is then pre blended, then micronizied to require particle through a Jet-mill. Mixture obtained is then mixed again in vessel to yield th