Herbicidal compositions

Details Herbicidal compositions Herbicidal compositions

2001-06-07

2003-04-08

Pryor, Alton (Department: 1616)

Plant protecting and regulating compositions

Plant growth regulating compositions

Plural active ingredients

Reexamination Certificate

active

06544929

ABSTRACT:

CROSS-REFERENCE TO PRIORITY APPLICATION
This application claims priority under 35 U.S.C. §119 of European Application No. EP 00112181.3, filed Jun. 7, 2000, the entire disclosure of which is hereby expressly incorporated by reference.
This invention relates to novel herbicidal compositions comprising isoxaflutole, glyphosate or glufosinate herbicide and a stabilizing agent.
In PCT/EP 98/07514 there are described compositions comprising isoxaflutole and glyphosate. Results are disclosed of tank mixture trials of the herbicides which demonstrated a biological synergy between the mixtures.
A problem however, which may exist with isoxazole derivatives such as isoxaflutole, is their instability under certain conditions. For example, in the presence of bases and certain adjuvants, the compounds can undergo ring opening to give a 1,3-dione compound. This can lead to difficulties in producing pre-mixed formulations containing an isoxazole and a partner herbicide.
Mixtures of glyphosate and a partner herbicide may provide an effective level of weed control, however, problems may arise where the two component formulations, e.g. of glyphosate and the partner herbicide, are incompatible, e.g. physically or chemically, with each other. For example, in a tank mix formulation, isoxaflutole may be degraded by the presence of certain adjuvant components necessary for glyphosate efficacy.
Chemical or physical incompatibility may also be significant in “pre-mix” formulations comprising two or more herbicides. Such formulations are often preferred as they ensure correct application rates of herbicides are applied to the locus.
The applicants have found that the presence of glycol, or polymers thereof and/or glycerol in “pre-mix” compositions comprising isoxaflutole and glyphosate or glufosinate improve the stability of isoxaflutole. Furthermore, activity on certain grass and broad leaf weeds may be improved.
Thus according to the invention there is provided a composition comprising:
(a) isoxaflutole;
(b) glyphosate or glufosinate and salts thereof; and
(c) a stabilizing amount of at least one compound selected from
(i) glycol,
(ii) polyethylene glycol,
(iii) polypropylene glycol,
(iv) glycerol,
(v) esters of (i) to (iv), and
(vi) ethers of (i) to (iv).
In the description that follows, unless otherwise specified, the percentages are by weight.
The compositions of the invention generally contain up to 90%, especially up to 75%, of active ingredients (i.e. components (a), (b) and (c) above), although it will be understood that this amount may vary depending on the nature of the composition and the solubility and/or dispersibility of the various components. Preferably the composition contains up to 55% of active ingredients, more preferably from 20 to 55%.
It will be understood that the glycol is generally a polymer of formula (I) or (II);
H[OCH
2
(CH
2
)
X
]
n
OH  (I)
H[OCH
2
CH(CH
3
)]
n
OH  (II)
wherein x is preferably one or two;
and n is such that the overall weight of the molecule is from 50 to 10,000, preferably from 200 to 600.
Examples of esters of the glycols or glycerol include allate, caprylate, cocoate, laurate, myristate, oleate, ricinolate and stearate esters. Compositions comprising polyethylene glycol are generally preferred.
Generally the amount of (c) is from 15 to 65% of the composition weight, although the exact amount may vary depending on the specific glycol present and the nature of the other formulants present.
Glyphosate which is N-(phosphonomethyl)glycine, is usually present in its acid form or as a derivative thereof, such as the isopropylammonium salt or the trimesium (trimethylsulfoxonium) salt. Glufosinate which is 4-[hydroxy(methyl)phosphinoyl]-DL-homoalanine, is usually present as the ammonium salt.
It will be understood that in certain cases the stability of the glyphosate or glufosinate herbicide may also depend on factors such as pH, and that the pH of the mixture may need to be adjusted by the skilled worker accordingly. Preferably the pH of the composition is in the range from 2 to 7, more preferably from 2.0 to 5.0.
The compositions of the invention are preferably provided in the form of pre-mixed formulations. Preferred formulations are in the form of suspension concentrates, emulsifiable concentrates, a gel, a suspo-emulsion, an emulsion concentrate, a wettable powder or a water dispersible granule or powder. Compositions in the form of suspension concentrates are particularly preferred.
Compositions of the present invention may be in association with, and are preferably homogeneously dispersed in, one or more compatible agriculturally-acceptable diluents or carrier and/or surface active agents [i.e. diluents or carriers and/or surface active agents of the type generally accepted in the art as being suitable for use on herbicidal compositions and which are compatible with components (a), (b) and (c)]. The term “homogeneously dispersed” is used to include compositions in which the components (a), (b) and (c) are dissolved in other components. The term “herbicidal compositions” is used in a broad sense to include not only compositions which are ready for use as herbicides but also concentrates which must be diluted before use. The herbicidal compositions may contain both a diluent or carrier and surface-active (e.g. wetting, dispersing, or emulsifying) agent. Surface-active agents which may be present in herbicidal compositions of the present invention may be of the ionic or non-ionic types, for example sulphoricinoleates, quaternary ammonium derivatives, products based on condensates of ethythene oxide with alkyl and polyaryl phenols, e.g. nonyl- or octyl-phenols, tristyryl phenols, condensates of ethylene oxide with alcohols, or carboxylic acid esters of any hydrosorbitols which have been rendered soluble by etherification of the free hydroxy groups by condensation with ethylene oxide, alkali and alkaline earth metal salts of sulphuric acid esters and sulphonic acids such as dinonyl- and dioctyl-sodium sulphonosuccinates and alkali and alkaline earth metal salts of high molecular weight sulphonic acid derivatives such as sodium and calcium lignosulphonates and sodium and calcium alkylbenzene sulphonates.
Suitably, the herbicidal compositions according to the present invention may comprise up to 10% by weight, e.g. from 0.05% to 10% by weight, of surface-active agent but, if desired, herbicidal compositions according to the present invention may comprise higher portions of surface-active agent, for example up to 15% by weight in liquid emulsifiable suspension concentrates and up to 25% by weight in liquid water soluble concentrates.
Examples of suitable solid diluents or carriers are aluminium silicate, microfine silicon dioxide, talc, chalk, calcined magnesia, kieselguhr, tricalcium phosphate, powdered cork, adsorbent carbon black and clays such as kaolin, attapulgite, diatomaceous earth, mica, alumina oxide, titanium oxide and bentonite. The solid compositions (which may take the form of dusts, granules or wettable powders) are preferably prepared by grinding the components (a), (b) and (c) with solid diluents or by impregnating the solid diluents or carriers with solutions of components (a), (b) and (c) in volatile solvents, evaporating the solvents and if necessary, grinding the products so as to obtain powders. Granular formulations may be prepared by absorbing components (a), (b) and (c) dissolved in suitable solvents, (which may, if desired, be volatile) onto the solid diluents or carriers in granular form and, if desired, evaporating the solvents, or by granulating compositions in powder form obtained as described above. Solid herbicidal compositions, particularly wettable powders and granules, may contain wetting or dispersing agents (for example of the types described above), which may also, when solid, serve as diluents or carriers.
Liquid compositions according to the invention may take the form of aqueous, organic or aqueous-organic solutions, suspensions and emulsions which may incorpo

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