NZ244308A - Herbicidal composition comprising a trifluoromethylpyridyloxyphenoxy propionic acid and a hydroxy imino alkylcyclohex-2-enone derivative - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £44308 i 'I 1 \ • I \ i Pr.orit> D:it-^j: v-un^icue Cccc'f.cal.cn PiltJ: Jl'.Vi. 2 7 APR 1995 Publication Date , \ocU P.O. Jo'.ir:--?1.

NO • <®*v * if • y * * V Vf c / /" •■ \ \ ^ /■■>.- , Patents Form No. 5 v*"/ / NEW ZEALAND -j PATENTS ACT 1953 COMPLETE SPECIFICATION SYNERGISTIC INTERACTION OF HERBICIDAL ARYLOXYPROPIONIC ACID DERIVATIVES AND CYCLOHEXANEDIONES WE, IMPERIAL CHEMICAL INDUSTRIES PLC., a British company of Imperial Chemical House, Millbank, London SWIP 3JF, UNITED KINGDOM hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: (followed by page la) -\a- PR-8659 SYNERGISTIC INTERACTION OF HERBICIDAL ARYLOXYPROPIONIC ACID DERIVATIVES AND CYCLOHEXANEDIONES Background of the Invention The protection of crops from weeds and other vegetation which inhibit crop growth is a constantly recurring problem in agriculture. To help combat this problem, researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use.

In some cases, active herbicides have been shown to be more effective in combination than when applied individually. The result is often termed "synergism", since the combination demonstrates a potency or activity level exceeding that which it would be expected to have, based on a knowledge of the individual potencies of the components. The present invention resides in the discovery that certain aryloxypro-pionic acid derivatives and certain cyclohexanediones, already known individually for their herbicidal potency, display a synergistic effect when applied in combination.

Prior Art The two classes of compounds forming the combination which is the subject of the present invention are independently known in the art for their effects on plant growth. Herbicidal aryloxypropionic acid derivatives are disclosed in U.S.

Patents Nos. 4,267,336, 4,317,913 and 4,414,391; British (followed by page 2) n- \ j e~-i "f -j 'v o Patents Nos. 1,599,121 and 2,002,368. Also, see the Pesticide Manual, 9th ed., edited by C. R. Worthing and R. J. Hance, pp. 400, 401 and 463.

Derivatives of cyclohexanediones are disclosed as herbicides in U.S. Patent 3,950,420, EPA 80301, EP-B-85529.

Description of the Invention It has now been discovered that synergism in the control of undesirable vegetation is exhibited by compositions comprising: (a) An aryloxypropionic acid derivative of the formula 0—CH-COOR, I 3 CH„ in which formula X is hydrogen or halogen; R1 is hydrogen, C^-Cg alkyl or C^-Cg alkoxyalkyl; and (b) a cyclohexanedione derivative of the ii (R) in which >&. R £ r ' '• R is independently hydrogen; halogen; nitro; cyano; C -Cf alkyl; or C..-C, alk*/l substituted with a substituenr lb i \ selected from the group consisting of halogen, nitro, hydroxy, C -Q alkoxy and C-C.. alkylthio; C -Cr alkenyl; C.-C, alkynyl; lb ID 2 O 2 o hydroxy; alkoxy; alkoxy substituted with a sub- stituent selected from halogen and C-C,. alkoxy; C_-C,. alkenyl- 16 2 o oxy; -Cg alkynyloxy; C^-C^ alkanoyloxy; (C^-Cg alkoxy)-carbonyl; cj-c6 alkylthio; C^-Cg alkylsulfinyl; C2.-C6 alkyl-sulfonyl; sulfamoyl; X- (C^-C alkyl)suifamovl; l^N-difC^-Cg alkyl)sulfamoyl; benzyloxy, substituted benzyloxy wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, C-C alkyl, C —C alkoxy and C.-C_ haloalkyl; the group 910 9 1 r, 1 O N'R R wherein R and R are independently selected from the group consisting of hydrogen, C.-C, alkyl, C-C, alkanoyl, 1 D 2. D benzoyl and benzyl, or the groups formyl and C--C, alkanoxvl and 2 o the oxime, imine and Schiff base derivatives thereof; R_ is C-C,. alkyl, C -Cc alkenyl, C_-Cc haloalkenyl, 2 ID 2 D 2 D C-C,, alkynyl, C-C.. haloalkynyl, a substituted C-C,. alkyl, 2 b 2 6 X b substituted with halogen, C^-Cg alkoxy, C^-Cg alkylthio, . i or substituted phenyl wherein the phenyl is substituted with halogen, nitro, cyano, C2-C6 alkyl, C^-Cg haloalkyl, C-C, alkoxy and C -Cc alkylthio; lb lb is hydrogen, alkyl, C^-Cg fluoroalkyl, C2-C6 alkenyl, C2~c6 alkynyl or phenyl; R^ is hydrogen or the keto tautomer; C2~C6 alkyl; C-C,. alkenyl; C-C- alkynyl; substituted C-C,. alkyl wherein 2 6 2 6 lb the alkyl group is substituted with C -Cg alkoxy, alkylthio, C -Cg alkoxycarbonyl, phenyl, and substituted phenyl wherein the benzene ring is substituted with 1 to 3 substituents selected from the group consisting of halogen, nitro, cyano, C-C. alkyl, C.-C, haloalkyl, C-C,. alkoxy, and 16 lb lb C-C- alkylthio; C-C-(alkyl) sulfonyl; benzene sulfonyl; 16 lb substituted benzene sulfonyl wherein the benzene ring is substituted with 1 to 3 substituents selected from the group consisting of halogen, nitro, cyano, alkyl, C^-Cg > r - , 1995 haloalkyl, C-C& alkoxy C -C& alkylthio; an acyl group ana an inorganic or organic cation; and n is an integer chosen from 2 to 5.

The terms "alkyl", and the like are used herein and branched-chain radicals. "alkoxy", "alkenyl", "alkylthio", to embrace both straight-chain Examples of aryloxypropionic acid derivatives useful in the present invention are: (D)-butyl 2-[4-(5-trifluoromethyl-2-pyridyloxy)-phenoxy]-propionate, (fluazifop-butyl); (fluazifop); (R)-2-[4 -(5-trifluoromethyl-2-pyridyloxy)phenoxy] propionic acid, (fluazifop-P and fluazifop-P-butyl); (RS)-2-[4-(3-chloro-5-trifluoromethyl-2—pyridyloxy) phenoxy]propionic acid, (haloxyfop); haloxyfop-etotyl; haloxyfop-methyl.

These and other aryloxypropionic acid derivatives within the scope of the invention can be prepared by the procedures described in U.S. Patents Nos. 4,267,336, 4,317,913, 4,414,391; EPA 23785; and British Patents Nos. 1,599,121 and 2,002,368. These references are hereby incorporated in their entirety.

Preferred cyclohexanediones included in the present invention are those in which the phenyl group is substituted with methyl groups and include: -(3-acetyl-2,4,6-trimethylphenyl)-2- [1-(ethoxy-imino)-propyl]-3-hydroxycyclohex-2-en-l-one; and 2-[1-(ethoxyimino)propyl]-3-hydroxy-5-(2,4,6-tri-methy1-3-butyrylphenyl)cyclohex-2-enone.

PR-S659 The most preferred substituents are on the 2- and 6-position of the phenyl ring and are preferably selected from halogen, methyl and methoxy.

These and other cyclohexanediones along with their tautomeric forms within the scope of the present invention, can be prepared by the procedures described in U.S. Patent 3,950,420, EP-A-0080301 and EP-B-0085529. These references are hereby incorporated in their entirety.

The terms "synergism" and "synergistic" are used herein to convey the result observed when a combination of herbicides demonstrates a potency in excess of that which the combination would be expected to produce on the basis of the potencies of each herbicide applied individually.

The term "herbicide" is used herein to denote a compound which controls or modifies the growth of plants. The term "herbicidally effective amount" is used to indicate the quantity of such a compound or combination of such compounds which is capable of producing a controlling or modifying effect. Controlling or modifying effects include all deviations from natural development, for example: kill, retardation, leaf burn, dwarfing and the like. The term "plant" refers to all physical parts of a plant, including seeds, seedlings, saplings, roots, tubers, stems, stalks, foliage and fruits.

In the compositions of this invention, the aryloxypropionic acid derivative:cyclohexanedione weight ratio at which the herbicidal response is synergistic, lies within the range of 1:5 to about 30:1, preferably about 1:5 to about 15:1 and most preferably about 1:2 to about 8:1.

Application rates will depend upon the particular compounds chosen for use, the particular plant species and degree of control desired. In general, the compositions of the invention are most efficiently employed at a rate of 0.001 PR-8659 to 50 pounds per acre (0.001 to 56 kilograms per hectare), preferably 0.001 to 25 pounds per acre (0.001 to 28 kilograms per hectare).

The following examples provide further illustrations demonstrating the synergistic herbicidal response of the present compositions.

Example I This example demonstrates the synergistic response of butyl (R)-2-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy] propionic acid (fluazifop-P-butyl) and 2-[1-(ethoxyimino)-propyl]-5-(2,4,6-trimethyl-3-butyryl phenyl)-l,3-cyclohexane-dione in combined postemergence application to the plants giant foxtail and shattercane.

Plastic pots were filled with 2 parts sandy loam and 1 part peat moss mixed together containing the commercial fungicide cis-N[(trichloromethyl)thio]-4-cyclohexene-l,2-dicarboximide (Captan®) and 17-17-17 fertilizer (percentages of N-P2OJ--l^O on a weight basis) . Each pot was seeded to a single plant species. The plant species included giant foxtail (Setaria faberi) and shattercane (Sorghum vulgare). The pots were placed in a greenhouse for approximately two weeks where they were watered regularly. The greenhouse temperature was approximately 85° F. day and 80° F. night.

At the end of this period, the fcliage on the emerged plants was sprayed with herbicidal emulsions formed by diluting emulsifiable concentrates of test compounds with adjuvants and water. The dilutions were made such that at a total spray volume of 25 gallons per acre, the amount of each test compound applied per pot corresponded to the desired application rate in ounces per acre. In control pots, the test compounds were applied individually at various application rates, whereas in the test pots, emulsions contained both compounds. Untreated pots were used as standards.

PR-8659 Sixteen days after treatment, the control and test pots were compared to the standards and rated visually in terms of percent control ranging from 0% to 100%, with 0% representing no injury to the plant species and 100% representing complete kill of all plants. All types of plant injury were taken into consideration.

For the plant species, the results of these tests are listed in Table I in the columns headed by the symbol "O" (indicating the "observed" results), each figure represent the average of three replications of the same test. These results are compared with the expected results, shown in the columns headed by the symbol "E", derived from the control data using Limpel's formula (Limpel et al., 1962, "Weed Control by Dimethylchloroterephthalate Alone and in Certain Combinations", Proc. NEWCC., vol. 16, pp. 48-53): E = X + Y - XY 100 where X = observed percent injury when one of the herbicides is used alone, and Y = observed percent injury when the other herbicide is used alone.

An asterisk (*) is used to indicate the tests where the results show synergism, i.e., where the observed result exceeds the expected result by at least 10 percent. It is clear from the table that synergism was observed at many of the application rates tested.

PR-8659 TABLE I Post-emergence Application1: Average of Three Replications 2 Application Rates % Control - 0:Observed. E:Expected (Oz/A) Giant Foxtail Shattercane A B 0 E 0 E Control Data 0.063 — 0 0 0.125 — 0 27 0.250 — 0 82 0.500 — 7 92 1.000 — 37 100 0.016 0 0 — 0.031 0 0 — 0.063 0 0 — 0.125 32 43 — 0.250 100 100 — — 0 0 Test Data 0. 063 0.016 0 0 0 0 0. 063 0. 031 0 0 3 0 0. 063 0. 063 0 23* 0 0. 063 0.125 75* 32 90* 43 0. 063 0.250 100 100 100 100 0.125 0. 016 0 0 27 0. 125 0. 031 0 0 33 27 0. 125 0. 063 13* 0 60* 27 0. 125 0. 125 75* 32 95* 58 0. 125 0.250 100 100 100 100 0. 250 0.016 0 0 85 82 0. 250 0. 031 3 0 85 82 0. 250 0. 063 13* 0 98* 82 0. 250 0. 125 80* 32 98 90 0. 250 0. 250 100 100 100 100 PR-8659 TABLE I (continued) Application Rates % Control - 0: Observed. E: Expected (Oz/h) Giant Foxtail Shattercane A B 0 E 0 E 0. 500 0. 016 7 92 92 0. 500 0. 03 13 7 98 92 0. 500 0. 063 78* 7 100 92 0. 500 0.125 80* 37 100 100 0. 500 0.250 100 100 100 100 1.000 0. 016 43 37 100 100 1.000 0. 031 68* 37 100 100 1. 000 0. 063 93* 37 100 100 1. 000 0. 125 98* 57 100 100 1. 000 0.250 100 100 100 100 2 = Treatments contained 1% Agridex = 16 days after application * = denotes synergistic effect shown A = Fluazifop-P-butyl; butyl (R)-2-[4-(5-trifluoromethyl-2- pyridyloxy)phenoxy]propionic acid B = 2-[l-(ethoxyimino)-propyl]-5-(2,4,6-trimethyl-3-butyryl-phenyl)-1,3-cyclohexanedione Example II In this example, the following formulations were prepared from 2-[1-ethoxyimino) propyl ]-3-hydroxy-5-(2 , 4, 6-trimethy1-3-butyrylphenyl)cyclohex-2-enone (Herbicide A), and the D isomer of butyl 2-[4-(5-trifluoromethyl-2-pyridyloxy)-phenoxy]-propionate (Herbicide B).

Formulation (a): Herbicide (A), 125 g/1; nonionic emulsifier (methyl capped derivative of Renex 650), 20 g/1; Aerosol OT 100, 30 g/1; and Teneco 500/100 to l liter.

Formulation (b): Herbicide (B), 125 g/1; phenyl sulfonate CALX, 45 g/1; Geopon SF 365, 45 g/1; Synperionic NPE 1800, 10 g/1 and Solvesso 100 to 1.0 liter.

Field plots 2m x 2m were seeded with oilseed rape (Brassica campestris) and the plant species, perennial ryegrass (Loiimn perenne) and annual bluegrass (Poa annua). At the PR-865S time of spraying, the oilseed rape was at the 2-true leaf growth stage, the annual bluegrass was at the 3-leaf, 2-tiller stage of growth, and the ryegrass was at the 2-leaf growth stage. Formulations (a) and (b) above were each blended separately with 0.1% by weight of Agral and the resulting solutions were applied sequentially at various rates. Injury ratings were taken by visual determination 87 days after treatment. A scale of 0 to 10 is used where 10 is equivalent to complete kill (or 100 percent control) and 0 indicates no visual injury (or 0 percent control) as compared to untreated control plants.

For the plant species, the results of these tests are listed in Table II in the columns headed by the symbol "O" (indicating the "observed" results). These results are compared with the expected results, shown in the columns headed by the symbol "E", as determined by the Colby formula.

The Colby formula is utilized to demonstrate the presence or absence of synergism (Colby, R. S., "Calculating Synergistic and Antagonistic Responses of Herbicide Combinations", 1967 Weeds, vol. 15, pp. 20-22): Expected effect = X + (10° X)Y 100 where X = observed effect of A and Y = observed effect of B The basis of demonstration by comparison with the Colby formula is that Herbicide (A) tested alone will kill a proportion of the target weeds and leave a proportion (a%) as survivors. Similarly, Herbicide (B) tested alone will leave (b%) as survivors. When combined, A + B will, however, if synergy is absent, act independently on the target weed, component A again leaving a% survivors, which survivors will be controlled by component B, with an overall effect of a% x b% 100 If, in practice, the percent control (degree of kill) is greater than that predicted by the Colby formula, PR-8659 synergism is provided by the difference between the observed and expected (Colby determined) results. As can be seen from Table II, synergism is widely evident.

TABLE II 2 Degree of Kill Application Rates 0;Observed. E:Expected (a/ha) Ryegrass Bluegrass A B 0 E O E 8 16 7 4 5 2 8 31 9 8 9 6 8 62.5 10 10 10 9 16 16 7 5 5 4 16 31 9 8 9 7 16 62.5 10 10 10 9 31 16 8 5 8 4 31 31 10 8 10 7 31 62.5 10 10 9 9 62.5 62.5 9 6 9 5 62.5 62.5 10 8 10 8 62.5 62.5 10 10 10 9 A = 2-[1-(ethoxyimino)propyl]-3-hydroxy-5-(2,4,6-trimethyl- 3-butyrylpheny1)cyclohex-2-enone.

B = D isomer of butyl-2-[4-(5-trifluoromethyl-2-pyridyloxy) phenoxy]propionate where O = no injury = complete kill PR-8659 Example III This example demonstrates the synergistic response of Herbicide (B) used in Example I and 5-(3-acetyl-2,4,6-trimethylpheny1)-2-[1-(ethoxyimino)-propyl]-3-hydroxycyclohex-2-en-l-one (Herbicide C).

The following formulations were prepared: Formulation (b) included Herbicide (B), 125 g/1; emulsifier 50 g/1; made up to 1.0 liter with Solvesso 100; and formulation (c) included Herbicide (C), 125 g/1; non-ionic emulsifier, 110 g/1; anisole, 400 g/1 made up to 1.0 liter with Solvesso 150.

Pots in the greenhouse were seeded with large crabgrass (Diaitaria sanguinalis), barnyardgrass (Echinochloa crusgalli), goosegrass IEleusine indica), guineagrass (Panicum maximum), and johnsongrass fSorghum halepense).

At the time of spraying, each plant species had 4 -5 leaves per plant. The above formulations were blended and the final solution blended with 0.1% by weight of AGRAL 90 and 1.0% by weight of ACTIPON. The final solution was applied through a greenhouse track sprayer at a volume of 2 00 liters per hectare.

Nineteen days after treatment, the degree of injury was rated visually in terms of percent control ranging from 0 to 100%, with 0% representing no control and 100% representing complete kill of all plants in the pot. The degree of kill was then assessed and compared with the expected kill as determined by the Colby formula presented in Example II. It is clear from Table III that synergism was observed at many of the application rates tested.

PR-8659 TABLE III Postemeraence Application 2 Application % Control - O:Observed; E:Expected Rates Crab- Goose- Guinea- Johnson- fa/ha) arass Millet arass arass arass B C 0 E 0 E O E 0 E 0 E 1 7 0 32* 7 45* 55* 8 1 - - 52* 17 97 92 48* 24 63 59 1 52* 7 100* 75 95* 78 95* 79 100 97 2 50* 3 98* 47 93* 85* 57 85* 37 2 60* 8 * 53 97 93 97* 65 100 70 2 92* 100* 66 98* 80 100* 90 100 98 B = Fluazifop-P-butyl; (D) butyl 2-[4(5-trifluoromethyl-2- pyridyloxy)phenoxy]-propionate C = 5-(3-acetyl-2,4,6-trimethylphenyl)-2-[1-ethoxyimino)-propyl]-3-hydroxycyclohex-2-en-l-one = 19 days after treatment * = Synergistic effect shown, the observed result exceeded the expected result by at least 10 percent The compositions of this invention are useful as herbicides demonstrating synergistic activity for the control of undesirable vegetation. The compositions can be formulated in the same manner in which herbicides are generally formulated. The compounds may be applied either separately or combined as part of a two-part herbicidal system.

The object of the formulation is to apply the compositions to the locus where control is desired by a convenient method. The "locus" is intended to include soil, seeds, and seedlings, as well as established vegetation.

Formulations will generally contain several additives. Among these are some inert ingredients and diluent carriers such as organic solvents, water, oil and water, water in oil emulsions, carriers of dust and granules, and surface active, wetting, dispersing, and emulsifying agents.

PR-8 659 i Fertilizers, such as ammonium nitrate, urea, potash and superphosphates may also be added.

Aids to rooting and growth, such as compost, manure, humus, sand, etc. may likewise be added.

The formulations are commonly dusts, wettable powders, granules, solutions or emulsifiable concentrates.

Dusts are free-flowing powder compositions containing the herbicidal compound impregnated on a particulate carrier. The particle size of the carrier is usually in the approximate range of 30 to 50 microns. Examples of suitable carriers are talc, bentonite, diatomaceous earth, and pyrophyl-lite. Anticaking and antistatic agents can be added, if desired. The composition generally contains up to 50% of active ingredient. Dusts, like liquid compositions, can be applied by spraying from boom sprayers, hand sprayers or airplanes.

Wettable powders are finely divided compositions comprising a particulate carrier impregnated with the herbicidal compound and additionally containing one or more surface active agents. The surface active agent promotes rapid dispersion of the powder in agueous medium to form stable, sprayable suspensions. A wide variety of surface active agents can be used, for example, long chain fatty alcohols; salts of sulfonic acid; esters of long chain fatty acids; and polyhydric alcohols, in which the alcohol groups are free, omega-substituted polyethylene glycols of relatively long chain length.

Granules comprise the herbicidal composition impregnated on a particulate inert carrier having a particle size of about 1 to 2 millimeters in diameter. The granules can be made by spraying a solution of the active ingredient in a volatile solvent onto the granular carrier. Suitable carriers in preparation of granules include clay, vermiculite, sawdust, granular carbon, etc.

PR-8659 Microcapsules and other slow release formulations are advantageous as formulations to deliver and distribute the active ingredients. Microcapsules consist of fully enclosed droplets or granules containing the active materials in which the enclosing material is an inert porous membrane, arranged to allow escape of the enclosed materials to the surrounding medium at controlled rates over a specified period of time. Encapsulated droplets are typically about 1 to 50 microns in diameter. The enclosed liquid typically constitutes about 50 to 9 5% of the weight of the entire capsule, and may contain an amount of solvent in addition to the active materials. Encapsulated granules are characterized by porous membranes sealing the openings of the granule carrier pores, trapping the liquid containing the active components inside for controlled release. A typical granule size ranges from 1 millimeter to l centimeter in diameter. In agricultural usage, the granule size is generally about 1 to 2 millimeters in diameter. Granules formed by extrusion, agglomeration or prilling are useful in the present invention as well as materials in their naturally occurring form. Examples of such carriers are vermiculite, starch sintered clay granules, kaolin, attapul-gite clay, sawdust and granular carbon. Useful encapsulating materials include natural and synthetic rubbers, cellulosic materials, styrene-butadiene copolymers, polyacrylonitriles, polyacrylates, polyesters, polyamides, polyureas, polyurethanes and starch xanthates.

The herbicidal compositions can also be applied to the soil in the form of a solution in a suitable solvent. Solvents frequently used in herbicidal formulations include kerosene, fuel oil, xylene, petroleum fractions with boiling ranges above xylene, and aromatic petroleum fractions rich in methylated naphthalenes.

Emulsifiable concentrates consist of an oil solution of the herbicide along with an emulsifying agent. Prior to use, the concentrate is diluted with water to form a suspended emulsion of oil droplets. The emulsifiers used are usually a mixture of anionic and nonionic surfactants. Other additives

Claims (15)

PR-8659 such as spreading agents and stickers can be included in the emulsifiable concentrate. It is not necessary that the compositions be admixed with the soil particles. After application by the above-discussed methods, they may be distributed below the soil surface to a depth of at least one-half inch by conventional means such as discing, dragging, or mixing.

1. A synergistic herbicidal composition comprising: (a) An aryloxypropionic acid derivative of the formula O—CH-COOR, V in which formula X is hydrogen or halogen; Rx is hydrogen, C^-Cg alkyl or Cj-Cg alkoxyalkyl; and (b) a cyclohexanedione derivative of the u in which R is independently hydrogen; halogen; nitro; cyano; C-C, alkyl; C-C, alkyl substituted with a substituent 16 lo selected from the group consisting of halogen, nitro, hydroxy, C-C, alkoxy and C-C, alkylthio; C--C, alkenyl; C-C, alkynyl 16 lb Z b Z o hydroxy; C^-C^ alkoxy; c1~c& alkoxy substituted with a substituent selected from halogen and C-C, alkoxy; C-C, alkenyl- 1 o Z o oxy; C2~C6 alkynyloxy; C2~C6 alkan°yloxy' (Ci-C6 alkoxy)~ carbonyl; C "Cg alkylthio; C1~C6 alkylsulfinyl; C^-Cg alkyl-sulfonyl; sulfamoyl; N-(C1~C6 alkyl)sulfamoyl; N,N-di(C1~C6 alky1)sulfamoyl; benzyloxy, substituted benzyloxy wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, - 17 - $ / <~-l r\ f\ L Li "t O U 0 c1~cg alkoxy and haloalkyl; the group NR R wherein R9 and are independently selected from the group consisting of hydrogen, C^-Cg alkyl, C2~Cg alkanoyl, • • i — t : r [roups rormyl and C,,-c - alkanoyl and the oxime, inline and Schiff base derivatives thereof; R2 is C^—Cg alkyl, C^-C^ alkenyl, C2~cg haloalkenyl, C2~Cg alkynyl, C2~C6 haloalkynyl, a substituted alkyl, substituted with halogen, C^-Cg alkoxy, c1~c6 alkylthio, phenyl or substituted phenyl wherein the phenyl is substituted with halogen, nitro, cyano, C1-Cg alkyl, haloalkyl, C -C alkoxy and C-C, alkylthio; lb lb R3 is hydrogen, C^-Cg alkyl, C1~Cg fluoroalkyl, C2-C6 alkenyl, C2~C6 alkynyl or phenyl; R. is hydrogen or the keto tautomer; C1~Cg alkyl; H C2"C , alkenyl; C-C, alkynyl; substituted C-C.. alkyl wherein b Z O 1 O the alkyl group is substituted with C-j.~C6 alkoxy, alkylthio, C^-Cg alkoxycarbonyl, phenyl, and substituted phenyl wherein the benzene ring is substituted with 1 to 3 substituents selected from the group consisting of halogen, nitro, cyano, C-C- alkyl, C-C,. haloalkyl, C-C,. alkoxy, and lo ID lb C1~Cg alkylthio; C-^-Cg (alkyl) sulfonyl; benzene sulfonyl; substituted benzene sulfonyl wherein the benzene ring is substituted with 1 to 3 substituents selected from the group consisting of halogen, nitro, cyano, C-^-Cg alkyl, c1_c6 haloalkyl, C-C, alkoxy or C-C, alkylthio; an acyl group and Id lb an inorganic or organic cation; and n is an integer chosen from 2 to 5. - 18 -

2. formula A synergistic herbicidal composition comprising: (a) An aryloxypropionic acid derivative of the 0—CH-C00R, I 1 CH3 in which X is hydrogen or halogen; is hydrogen, C^-Cg alkyl or C^-Cg alkoxyalkyl; and (b) a cyclohexanedione of the formula R CH. •CH. 0 ^N0R2 in which R is formyl or C2-Cg alkanoyl; alkyl; alkyl; jen or ■ at a weight ratio of (a) to (b) of from 1.0:0.001 to 20:1, R2 is C -Cg alkyl; R3 is C1~C6 R^ is hydrogen or the keto tautomer

3. A composition according to Claim 2 further comprising adjuvants.

4. A composition according to Claim 2 in which (a) is the D isomer of butyl 2-[4-(5-trifluoromethyl-2-pyridyloxy) phenoxy]-propionate. ■V^ - 19 - V." '

5. A composition according to Claim 4 in which (b) is 2-[1-(ethoxyimino)propyl]-3-hydroxy-5-(2,4,6-trimethyl-3-butyrylphenyl)cyclohex-2-enone or the keto tautomer.

6. A composition according to Claim 4 in which (b) is 2-[1-(ethoxyimino)propyl]-3-hydroxy-5-(2,4,6-trimethyl-3-acetylphenyl)cyclohex-2-enone.

7. A composition according to Claim 2 in which X is hydrogen or chlorine and R1 is hydrogen.

8. A composition according to Claim 7 in which R is acetyl or butyryl; R2 and R3 are ethyl; and R4 hydrogen or the keto tautomer.

9. A composition according to Claim 8 in which the weight ratio of (a) to (b) is from 1:2 to 8:1.

10. A composition according to Claim 9 further comprising adjuvants.

11. A synergistic herbicidal composition comprising (a) A 5-trifluoro-substituted-2-pyridyloxy-phenoxy propionic acid derivative optionally substituted at the 3-position with halogen; and (b) a tetrasubstituted 5-phenyl-[2-(l-alkoxy-iminoalkyl) cyclohexanedione derivative at a weight ratio of (a) to (b) of 1:2 to 8:1. - 20 - 2 4 4 J 0 8PR-8659

12. A method of controlling undesirable vegetation which comprises applying to the locus where control is desired an herbicidal composition comprising a mixture of: formula (a) An aryloxypropionic acid derivative of the 0—CH-COOR I ] CH„ in which X is hydrogen or halogen; Rx is hydrogen, C^Cg alkyl or alkoxyalkyl; and (b) a cyclohexanedione of the formula in which R is formyl or c2~c6 alkanoyl; R2 is alkyl; R3 is C^-Cg alkyl; and R, is hydrogen or the keto tautomer at a weight ratio of (a) to (b) of from 1.0 to 0.001 to 20:1.

13. A method according to Claim 12 wherein (a) is the D isomer of butyl 2-[4-(5-trif luoromethyl-2-pyridyloxy)-phenoxy ]-propionate and (b) is 2-[ 1-(ethoxyimino) propyl]-3-hydroxy-5- (2,4, 6-trimethyl-3-butyrylphenyl) cyclohex-2-enone or the keto tautomer. - 21 - r : " n fl 22

14. A synergistic herbicidal composition as claimed in any one of claims 1-11, substantially as herein described.

15. A method of controlling undesired vegetation as claimed in claim 12 or claim 13, substantially as herein described with reference to the Examples* IMPERIAL CHEMICAL INDUSTRIES PLC Their Attorneys BALDWIN, SON & CAREY