FIELD OF THE INVENTION
The present invention relates to stabilized or/and synergistic compositions comprising bispyribac-sodium and compounds having sulfonylurea functional group.
BACKGROUND OF THE INVENTION
This section includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the present invention, or that any publication specifically or implicitly referenced is prior art.
Weeds are plants that are considered unwanted when they grow in a human controlled settings like farm fields, gardens, lawns, parks etc. As weeds reproduce quickly and can survive in almost any type of conditions they pose a threat to the yield of crops as they compete with crops for sunlight, nutrients, water etc. supplied to crops. Weeds also provide hosts and vectors for plant pathogens thereby giving them the opportunity to infect and degrade the quality of the products produced by the crops. They also provide food and shelter to various pests which are detrimental to the produce of crops.
Many recurring problems in agriculture involve controlling growth of undesirable vegetation that can, for instance, inhibit crop growth. A wide range of active herbicide compounds have been developed and used to control weeds in the agricultural industry. These active herbicide compounds are commercially available in various forms. While some of these active herbicide compounds are partially successful, their efficacy is limited in controlling certain weeds and the problem of controlling a broad spectrum of weeds still exists. In addition, many herbicidal formulations presently on the market are used in relatively high concentrations and volumes which cause high cost, phytotoxic problem, damage to desirable plant species and their residues detrimental to the succeeding crop.
To enable the efficient elimination or controlling of unwanted weeds in agriculture and related endeavors, it is desirable to use effective herbicides. Formulations containing herbicides are desirable in agricultural and related endeavors in order to effectively distribute the active ingredient to the area where weed control is desired. Physical stability is most important in this type of formulation in order to ensure the small amount of the herbicide is fully effective. A pesticide suspension is a homogeneous mixture of small solid particles of pesticide suspended in a liquid medium. During periods of non-agitation, the solid particles with a density greater than the density of the liquid medium will settle toward the bottom of the container and homogeneity is not maintained. Similarly, solid particles with a density less than the density of the liquid medium will settle toward the top of the container and homogeneity is not maintained. The loss of homogeneity can cause product failure if it results in non-uniform applications of the pesticide, and plugging of strainers and nozzles used with application equipment. The production of a stable suspension concentrate formulation most of times are difficult due to the formation of large crystals while large crystals grow larger or form agglomerates in the process known as Ostwald ripening. The drawbacks to Ostwald ripening include limited utility of the formulation because an acceptable shelf-life may not be obtained. For instance, a two year shelf-life is typically needed for a successful commercial product in agrochemicals. Also, crystals that grow too large may plug spray equipment and may not stay suspended in the spray tank or concentrated formulation. Consequently, there is a need for maintaining a stable suspension concentrate with a uniform particle size distribution (i.e. no large crystals) is most important for this type of formulation in order to prevent settling of particles during storage.
Further, in some cases, herbicidal active compounds have been shown to be more effective in combination than when applied individually and this is referred to as “synergism”. As described in the Herbicide Handbook of the Weed Science Society of America, Eighth Edition, 2002, p.462, “synergism is an interaction of two or more factors such that the effect when combined is greater than the predicted effect based on the response to each factor applied separately.” Especially, in view of the environmental concern and to achieve results in very economical way, various attempts have been made to maximizing the performance of known active ingredients. Thus, there is a need in the art for a new and improved herbicide formulation which in combination exhibit excellent herbicidal activity towards target weeds, exhibits a very strong herbicidal activity to a wide range of agricultural weeds even at a low concentration, better selectivity, lower undesirable impact, lower production and market cost etc. The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
SUMMARY OF THE INVENTION
The present invention relates to stabilized or/and synergistic compositions for achieving effective and economical control of undesired weeds. The non aqueous suspension concentrate formulations of bispyribac sodium known in the art are sterically unstable and undergo separation on standing primarily due to Ostwald ripening and chlorimuron-ethyl is also easily subjected to hydrolysis. It has unexpectedly found that the addition of compounds having sulfonylurea functional group to bispyribac-sodium provide thermodynamic stability in suspension concentrate formulation by exhibiting negligible separation which in turn reduce Ostwald ripening. Moreover, chlorimuron-ethyl in the form of ß-cyclodextrin inclusion complex prevents the hydrolysis of chlorimuron-ethyl. It has also unexpectedly found that composition comprising a bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex leads to much better control of the different weeds in comparison to the individual formulations. Consequently, stabilized formulations of bispyribac-sodium are obtained and as well as the toxic effects of the residues of the active ingredients on the biotic and abiotic part of the ecosystem are minimized.
The existing arts neither disclose that the addition of compounds containing sulfonylurea functional group to bispyribac-sodium provide thermodynamic stability which in turn prevent Ostwald ripening nor they disclose that the combination of bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex provide synergistic effect or use of chlorimuron-ethyl in the form of ß-cyclodextrin inclusion complex prevent the hydrolysis of chlorimuron-ethyl.
In accordance with one of the embodiment of the present invention, the present invention relates to a herbicidal composition comprising bispyribac-sodium, one or more compounds having sulfonylurea functional group and at least one agriculturally acceptable adjuvant.
In accordance with one of the embodiment of the present invention, the compounds having sulfonylurea functional group are sulfonylurea herbicide.

In accordance with one of the embodiment of the present invention, the sulfonylurea herbicides are metsulfuron-methyl, chlorimuron-ethyl, azimsulfuron, bensulfuron-methyl, chlorsulfuron, ethametsulfuron-methyl, flupyrsulfuron-methyl, nicosulfuron, rimsulfuron, sulfometuron-methyl, thifensulfuron-methyl, tribenuron-methyl, and triflusulfuron-methyl or its inclusion complex with ß-cyclodextrin.

In accordance with one of the preferred embodiment of the present invention, the sulfonylurea herbicides are metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex.

In accordance with one of the embodiment of the present invention, weight ratio of bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex is in a range from about 1:0.1:0.1 to 1:0.3:0.3.
In accordance with one of the embodiment of the present invention, the bispyribac-sodium is present in an amount of 5-10% by weight of the formulation.
In accordance with one of the embodiment of the present invention, the metsulfuron-methyl is present in an amount of 0.5-5% by weight of the formulation.
In accordance with one of the embodiment of the present invention, the chlorimuron-ethyl ß-cyclodextrin complex is present in an amount of 0.5-6% by weight of the formulation.
In accordance with one of the embodiment of the present invention, the composition is formulated as a suspension concentrate (SC), wettable powder (WP), a micro emulsion (ME), an encapsulated suspension (CS), or a water dispersible granule (WG).
In accordance with one of the preferred embodiment of the present invention, the composition is formulated as a suspension concentrate (SC).
In accordance with one of the embodiment of the present invention, the agriculturally acceptable adjuvants in the suspension concentrate formulation are selected from the group consisting of Adsee 900, lankropol KPH, ethylan 500 LQ, propylene glycol, biocide, silicone defoamer, aluminium oxide and trisiloxane ethoxylate.
The features of the invention will become more apparent from the detailed description set forth herein below.
DESCRIPTION OF THE INVENTION

The following is a description of embodiments of the present invention. The embodiments are in such details as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.
As used herein, the term "stable composition" refers to compositions that are stable physically and / or chemically for defined periods of time to the environments in which they are produced, transported and/ or stored. Aspects of "stable compositions" include, but are not limited to: physical stability at temperatures that range from about 0° C. to about 60° C , homogeneity, pourability, liquids that do not exhibit appreciable sedimentation or Ostwald ripening of the dispersed particles, compositions that form little or no precipitated solids or exhibit phase separation, compositions that readily disperse when poured into a spray tank of water and retain their biological efficacy when applied, for example, by spray application to target pests.
Unless specifically defined otherwise, all technical and scientific terms used herein shall be taken to have the same meaning as commonly understood by one of ordinary skill in the art (e.g., in agricultural chemistry, dendrimer chemistry, pesticide chemistry and formulations, and biochemistry).
Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including”, but not limited to.”
As used in the description herein and throughout the claims that follow, the meaning of “a”, “an” and “the” includes plural reference unless the context clearly dictates otherwise.
In some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment.
As used herein, the term "herbicide" or related terms means capable of being toxic to a plant (e.g., a weeds), controlling a plant, killing a plant, inhibiting the growth of a plant, and/or inhibiting the reproduction of a plant.
As used herein, the term "weed" means any plant targeted for treatment with a formulation of the invention. Target plants can be nuisance, unwanted, noxious, weedy, invasive, or harmful plant or vegetation (e.g., harmful to animals, harmful to ornamental plants, crops, etc.).
In accordance with an embodiment of the invention, the active ingredients/compounds used in the present invention are in the form of a free acid, salt, or an ester.
In accordance with an embodiment of the invention, there is provided a stabilized composition comprising of bispyribac-sodium and compounds having sulfonylurea functional group.
In accordance with a preferred embodiment of the invention, the compounds having sulfonylurea functional group include but not limited to sulfonylurea herbicide such as metsulfuron-methyl and chlorimuron-ethyl, azimsulfuron, bensulfuron-methyl, chlorsulfuron, ethametsulfuron-methyl, flupyrsulfuron-methyl, nicosulfuron, rimsulfuron, sulfometuron-methyl, thifensulfuron-methyl, tribenuron-methyl, and triflusulfuron-methyl or its inclusion complex with ß-cyclodextrin.
In accordance with an embodiment of the invention, the stabilized composition comprising of bispyribac-sodium and compounds having sulfonylurea functional group is present in suspension-concentrate formulation .
In accordance with an embodiment of the invention, there is provided a synergistic herbicidal composition comprising of bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex.
In accordance with an embodiment of the invention, there is provided a stabilized and synergistic herbicidal composition comprising of bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex.
In some embodiments of the present invention, the concentration of active ingredients in the composition is from about 5 to 15 percent by weight of all components in the composition.
In some embodiments of the invention, the concentration of bispyribac-sodium is from about 5% weight to about 10% weight of all components in the composition, the concentration of metsulfuron-methyl is from about 0.5% weight to about 5% weight of all components in the composition, and the concentration of chlorimuron-ethyl ß-cyclodextrin complex is from about 0.5% weight to about 6% weight of all components in the composition.
In some embodiments of the invention, the weight ratio of bispyribac-sodium to metsulfuron-methyl to chlorimuron-ethyl ß-cyclodextrin complex in the composition is within the range from about 1:0.1:0.1 to about 1:0.3:0.3.
In a preferred embodiment of the present invention, the composition as discussed herein also contain one or more auxiliaries. The auxiliaries employed in the composition will depend upon the type of formulation and/or the manner in which the formulation is to be applied by the end user. Suitable auxiliaries which may be comprised in the composition according to the invention are all customary formulation adjuvants or components, such as extenders, carriers, solvents, surfactants, stabilizers, anti-foaming agents, anti-freezing agents, preservatives, antioxidants, colorants, thickners, solid adherents and inert fillers.
The herbicidal composition of the present invention may also comprise further active ingredients such as other herbicides and /or insecticides.
The following examples of formulations according to the invention are presented to illustrate, but not to restrict, this invention:
FORMULATION EXAMPLES
A suspension concentrate formulation was prepared having the composition summarized in the following Table:
Ingredient Concentration (% w/w)
Bispyribac-sodium 9.1
Metsulfuron-methyl 1.2
Chlorimuron-ethyl ß-cyclodextrin complex 4.8
Adsee 900 (alcohol ethoxylate) 41.2
Lankropol KPH (sodium di-octyl sulphosuccinate) 25
Ethylan 500 LQ (polyalkoxylated butyl ether) 10
Propylene glycol 3
Biocide 0.2
Silicone defoamer 0.5
Aluminium oxide 3.0
Trisiloxane ethoxylate 2.0
Preparation of chlorimuron-ethyl ß-cyclodextrin complex: To 20 ml of N,N-dimethylacetamide was added 3.6g of ß-cyclodextrin and 1.4 g of chlorimuron-ethyl. The mixture was stirred at 25-60ºC for 4 hours and allowed to stand overnight, 200 ml of water was added and the inclusion complex of chlorimuron-ethyl ß-cyclodextrin complex was separated.
Further, 41.2 parts by weight of an alcohol ethoxylate such as Adsee 900, 25 parts by weight of sodium dioctyl sulfosuccinate such as Lankropol KPH and 10 parts by weight of an polyoxyalkylene glycolbutyl ether such as Ethylan 500LQ were mixed and 3.0 by parts of propylene glycol, 0.5 parts by weight of a silicone defoamer, 0.2 parts by weight of a biocide and 3.0 parts by weight of Aluminium oxide was added and the material was homogenized. To the above suspension, 1.2 parts by weight of metsulfuran-methyl, 4.8 parts by weight of chlorimuron-ethyl ß-cyclodextrin complex, and 9.1 parts by weight of bispyribac-sodium were added. The material was mixed and pulverized in a bead mill to a particle size D90 less than 10 micron. The pulverized material was post blended and under gentle stirring 2.0 parts by weight of Trisiloxane ethoxylate was added.
The suspension stability of bispyribac sodium 10% SC w/v prepared in absence of compounds having sulfonylurea functional group and that prepared with compounds having sulfonylurea functional group and suspension stability was checked. Surprisingly, it was found that the compounds having sulfonylurea functional group such as sulfonylurea herbicides helped in stabilization of bispyribac sodium. Moreover, chlorimuron-ethyl in the form of ß-cyclodextrin inclusion complex prevents the hydrolysis of chlorimuron-ethyl.
The compositions comprising bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin inclusion complex are also tested to evaluate the bio-efficacies for the control of the weeds. The expected efficacies for active ingredient combinations were determined using Colby’s formula (Colby, S.R. (Calculating synergistic and antagonistic responses of herbicide combinations, Weeds, 15, pp. 20-22, 1967) and compared with observed efficacies and it was found that formulations comprising bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex of the present invention were effective against weeds, in fact, synergistic effect was obtained.
Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto.

CLAIMS:
1. A herbicidal composition comprising:
(a) bispyribac-sodium;
(b) one or more compounds having sulfonylurea functional group; and
(c) at least one agriculturally acceptable adjuvant.

2. The herbicidal composition as claimed in claim 1, wherein compounds having sulfonylurea functional group are sulfonylurea herbicide.

3. The herbicidal composition as claimed in claim 2, wherein sulfonylurea herbicides are metsulfuron-methyl, chlorimuron-ethyl, azimsulfuron, bensulfuron-methyl, chlorsulfuron, ethametsulfuron-methyl, flupyrsulfuron-methyl, nicosulfuron, rimsulfuron, sulfometuron-methyl, thifensulfuron-methyl, tribenuron-methyl, and triflusulfuron-methyl or its inclusion complex with ß-cyclodextrin.

4. The herbicidal composition as claimed in claim 3, wherein sulfonylurea herbicides are metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex.

5. The herbicidal composition as claimed in any of the preceding claims, wherein weight ratio of bispyribac-sodium, metsulfuron-methyl and chlorimuron-ethyl ß-cyclodextrin complex is in a range from about 1:0.1:0.1 to 1:0.3:0.3.

6. The synergistic herbicidal composition as claimed in any of the preceding claims, wherein the bispyribac-sodium is present in an amount of 5-10% by weight of the formulation.

7. The synergistic herbicidal composition as claimed in any of the preceding claims, wherein the metsulfuron-methyl is present in an amount of 0.5-5% by weight of the formulation.

8. The synergistic herbicidal composition as claimed in any of the preceding claims, wherein the chlorimuron-ethyl ß-cyclodextrin complex is present in an amount of 0.5-6% by weight of the formulation.

9. The synergistic herbicidal composition as claimed in any of the preceding claims, wherein the composition is formulated as a suspension concentrate (SC), wettable powder (WP), a micro emulsion (ME), an encapsulated suspension (CS), or a water dispersible granule (WG).

10. The synergistic herbicidal composition as claimed in any of the preceding claims, wherein the composition is formulated as a suspension concentrate (SC).

11. The synergistic herbicidal composition as claimed in claim 10, wherein agriculturally acceptable adjuvants are selected from the group consisting of Adsee 900, lankropol KPH, ethylan 500 LQ, propylene glycol, biocide, silicone defoamer, aluminium oxide and trisiloxane ethoxylate.