WO2008058617A2

WO2008058617A2 - Herbicidal synergistic composition comprising a sulfonylurea herbicide and pretilachlor

Info

Publication number: WO2008058617A2
Application number: PCT/EP2007/009262
Authority: WO
Inventors: Georg Rüdiger KOTZIAN
Original assignee: Syngenta Participations AG
Current assignee: Syngenta Participations AG
Priority date: 2006-11-13
Filing date: 2007-10-25
Publication date: 2008-05-22
Anticipated expiration: 2009-05-13
Also published as: CN101528036B; WO2008058617A3; MY158096A; CN101528036A; TW200833247A

Abstract

The present invention relates to the use of (i) a compound of formula I, wherein M, n, r and s are as defined in the claims, to synergistically enhance the herbicidal activity of a composition comprising pretilachlor, and to the use of pretilachor to synergistically enhance the herbicidal activity of a composition comprising a compound of formula (I). The invention thus extends to novel herbicidal synergistic compositions comprising as active ingredients (i) a compound of formula I and (ii) a synergistically effective amount of pretilachlor. The invention also relates to such compositions when formulated, as well as the use of such compositions and formulations in the control of undesired plant growth in crops of useful plants.

Description

HERBICIDAL SYNERGISTIC COMPOSITION

The present invention relates to the use of (i) a compound of formula

wherein M is an alkali metal or alkaline earth metal; n is 1 or 2; r and s are each independently of the other 0, ¹A 1 , 114, 2, 2% or 3; and L is ethyl acetate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, acetone, butanone, methylene chloride, trichloromethane, trichloroethane, tetrahydrofuran, diethyl ether, 1 ,2-dimethoxyethane, dioxane, methyl tert-butyl ether, chlorobenzene, toluene or xylene; to synergistically enhance the herbicidal activity of a composition comprising pretilachlor, and to the use of pretilachor to synergistically enhance the herbicidal activity of a composition comprising a compound of formula (I). The invention thus extends to novel herbicidal synergistic compositions comprising as active ingredients (i) a compound of formula I and (ii) a synergistically effective amount of pretilachlor. The invention also relates to such compositions when formulated, as well as the use of such compositions and formulations in the control of undesired plant growth such as weeds (e.g. grasses and broad-leaved weeds) in crops of useful plants, in particular in crops of rice.

Compounds of formula I have herbicidal activity and are known from WO 00/52006. Trifloxysulfuron-sodium (1-(4,6-dimethoxtpyrimid-2-yl)-3-[3-(2,2,2-trifluoroethoxy)-2- pyridylsulfonyl] urea, sodium salt) is an example of a compound of formula I.

Pretilachlor (2-chloro-2',6'-diethyl-N-(2-propoxyethyl)acetanilide) also exhibits herbicidal activity and is described for example in GB-A-1 438 311 and GB-A-1 438 312.

Trifloxysulfuron-sodium (833) and pretilachlor (656), as well as agronomically acceptable salts thereof, are also described, in "The e-Pesticide Manual", version 3.1 , 13th Edition, Ed. CDC Tomlin, British Crop Protection Council, 2004-2005. Synergisitic herbicidal compositions comprsing other herbicides are known from the prior art, for example, WO 03/028461 describes synergistic herbicidal compositions comprising pyriftalid as a synergic herbicide, and discloses a four-way mixture of pyriftalid, cinosulfuron, pretilachlor and trifloxysulfuron.

The present invention is based on the surprising observation that a compound of formula I is synergic with respect to the herbicidal activity of pretilachlor and vice versa (i.e. pretilachlor is synergic with repect to the herbicidal activity of a compound of formula I. Thus, compounds of formula I and pretilachlor may be used to enhance in a synergistic manner the herbicidal activity of each other. This unexpected synergistic effect is capable of controlling, both pre-emergence and post-emergence, the majority of weeds occurring in crops of useful plants without significantly damaging the useful plants.

Thus, according to one aspect of the present invention, there is provided an herbicidal synergistic composition comprising as active ingredients a mixture of: (i) a compound of formula I

wherein, M is an alkali metal or alkaline earth metal; n is 1 or 2; r and s are each independently of the other O, V₂, 1 , VA, 2, 2V* or 3; and L is ethyl acetate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, acetone, butanone, methylene chloride, trichloromethane, trichloroethane, tetrahydrofuran, diethyl ether, 1 ,2-dimethoxyethane, dioxane, methyl tert-butyl ether, chlorobenzene, toluene or xylene; and (ii) a synergistically effective amount of pretilachlor, or salt thereof, with the proviso that said herbicidal synergistic composition does not consist of as active ingredients: pyriftalid, cinosulfuron, pretilachlor and trifloxysulfuron.

M is defined herein as an alkali metal or alkaline earth metal, preferably sodium, potassium, magnesium or calcium, most preferably sodium. In some embodiments, the compounds of formula I employed in the invention are those wherein L is dioxane or tetrahydrofuran. In further embodiments, compounds of formula I wherein n is 1 , and M is sodium are especially preffered. It is particularly preferred that the compound of formula I is one wherein M is sodium, n is 1 , r is 0 and s is 0, or one wherein M is Na, n is 1 , r is 0 and s is 1. This latter compound (which is most preferred for use in the invention) is commonly known as trifloxysulfuron sodium.

The skilled man will appreciate, in particular from WO 00/58066, that the compounds of formula I exist in different crystal forms or modifications. The present invention encompasses the use of any one of the crystal modifications of a compound of formula

In particular, the amorphous solid form of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 0 (i.e. the A modification) may be employed in the invention. The amorphous solid form may also be used in the preparation of other crystal modifications, such as the C modification, which may also be employed in the invention. Details of crystal modifications of particular compounds of formula I₁ which may be used in the invention, are shown below.

a) the B modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 , characterised by the X-ray powder pattern having drAi/intensity: 10.0/medium; 9.2/strong; 8.6/very weak; 8.1/weak; 7.2/strong; 6.9/strong; 6.4/medium; 5.82/strong; 5.75/strong; 5.64/very strong; 5.53/very weak; 5.13/medium; 4.97/very strong; 4.65/medium; 4.30/very strong; 4.22/weak; 4.15/very weak; 4.02/weak; 3.94/weak; 3.79/medium; 3.73/weak; 3.68/medium; 3.61/weak; 3.58/weak; 3.52/very strong; 3.42/very weak; 3.37/weak; 3.31 /very weak; 3.27/very weak; 3.23/weak; 3.18/medium; 3.08/very weak; 3.03/very weak; 2.95/very weak; 2.87/strong; 2.82/very weak; 2.79/very weak; 2.73/very weak; 2.68/very weak; 2.65/very weak; 2.63/very weak; 2.60/weak; 2.57/weak;

b) the J modification of the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is V* and s is 0, characterised by the X-ray powder pattern having drAi/intensitv: 15.7/weak; 10.2/very strong; 8.2/weak; 7.8/weak; 7.3/weak; 6.7/weak; 6.5/very weak; 6.2/medium; 5.64/very weak; 5.53/weak; 5.42/weak; 5.09/weak; 4.96/medium; 4.86/very weak; 4.60/medium; 4.37/medium; 4.24/weak; 4.11 /very strong; 3.95/very weak; 3.90/weak; 3.81 /very weak; 3.71/medium; 3.62/weak; 3.52/very weak; 3.43/strong; 3.37/weak; 3.32/very weak; 3.27/weak; 2.94/very weak; 2.82/medium;

c) the K modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 0, characterised by the X-ray powder pattern having dfAl/intensity: 13.4/weak; 10.1/very weak; 9.3/very strong; 7.8/weak; 6.9/very weak; 6.7/very weak; 5.63/very weak; 5.35/medium; 4.66/weak; 4.44/very weak; 4.35/weak; 4.12/strong; 3.94/strong; 3.87/very weak; 3.76/weak; 3.61/medium; 3.49/very weak; 3.40/very weak;

d) the C modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 , characterised by the X-ray powder pattern having dfAi/intensity: 13.1/medium; 11.0/very strong; 8.8/weak; 7.7/very strong; 7.2/very strong^"; 7.0/weak; 6.4/weak; 6.2/strong; 5.96/weak; 5.90/weak; 5.64/strong; 5.47/weak; 5.34/medium; 5.19/weak; 4.79/weak; 4.74/medium; 4.64/very weak; 4.55/strong; 4.47/weak; 4.35/strong; 4.26/medium; 4.13/weak; 4.06/very weak; 3.92/very strong; 3.87/weak; 3.79/very strong; 3.67/weak; 3.61/medium; 3.58/strong; 3.47/weak; 3.32/very weak; 3.24/medium; 3.14/weak; 3.12/weak; 3.07/weak; 3.04/strong; 2.97/very weak; 2.92/very weak; 2.88/weak; 2.82/weak; 2.77/very weak; 2.74/very weak; 2.69/weak; 2.66/very weak; and

e) the I modification of the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1 and s is 1 , characterised by the X-ray powder pattern having drAi/intensity: 11.6/weak; 9.8/very weak; 8.0/very strong; 7.6/medium; 6.7/strong; 6.4/very weak; 6.3/weak; 6.1/very weak; 5.80/medium; 5.66/very weak; 5.47/strong; 5.12/very weak; 5.08/very weak; 4.84/weak; 4.76/weak; 4.47/strong; 4.40/weak; 4.21/medium; 4.19/medium; 4.15/very weak; 4.00/very weak; 3.93/very weak; 3.84/medium; 3.72/very strong; 3.58/medium; 3.52/medium; 3.32/very weak; 3.28/very weak; 3.25/very weak; 3.11 /very weak; 3.07/very weak; 2.95/very weak; 2.86/weak; 2.82/very weak; 2.75/very weak; 2.57/weak; 2.49/very weak.

In preferred embodiments, the K, C and/or B modifications are used. These may be made as described below. a) the K modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 0, prepared by drying the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1/2 and s is 0 (J modification) at a temperature of from 35⁰C to 65°C in vacuo; b) the C modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 , prepared by either i) bringing the substantially amorphous form (A modification) into contact with air of 98 % relative humidity, or ii) adding water to the K modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 0, in a ratio of water to K modification of from 0.1:1 to 0.4:1 and separating off and drying the resulting product at a temperature of 30-90⁰C and a pressure of from 1 to 10 kPa; c) the B modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1, prepared by adding water to the compound of formula I wherein M is sodium, n is 1 and L, r and s are as defined for formula I, in a ratio of water to that compound of from 0.5 : 1 to 20 : 1 , filtering, and drying the filtration residue at a temperature of 30- 90⁰C and a pressure of from 1 to 10 kPa, or preferably prepared by adding water to the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1/2 and s is 0 (K modification), or to the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1/2 and s is 0 (J modification), or to the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1 and s is 1 (I modification), or to the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 (C modification), in a ratio of water to K, J, I or C modification of from 0.5 : 1 to 20 : 1 , filtering, and drying the filtration residue at a temperature of 30-90⁰C and a pressure of from 1 to 10 kPa.

The K modification, has surprisingly high thermodynamic stability and non-hygroscopic properties. A high degree of stability, especially in the presence of water, is also exhibited by the B modification. Such properties are especially advantageous for the preparation of formulations of not only the active ingredient of formula I, but also in preparing formulations comprising herbicidal synergistic compositions of the invention.

The compounds of formula I can be prepared in accordance with a general process by reacting a compound of formula III

in ethyl acetate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, acetone, butanone, methylene chloride, trichloromethane, trichloroethane, tetrahydrofuran, diethyl ether, 1 ,2-dimethoxyethane, dioxane, methyl tert-butyl ether, chlorobenzene, toluene or xylene, with a compound of formula V

wherein M is as defined herein for formula I.

The reaction of the compound of formula III with the compound of formula IV is carried out at temperatures of from -20⁰C to 180⁰C, a temperature range of 30 - 80⁰C being preferred. The compounds of formulae III and IV can be used in equivalent stoichiometric amounts, but a slight excess of isocyanate may be advantageous.

The preparation of the starting compound of formula III is described, for example, in EP-A-O 232 067, page 29. The compounds of formula IV can be prepared, for example, by converting a compound of formula V

wherein R₁ is -CH₂-phenyl or isopropyl, by aqueous chlorination into the compound of formula Vl

That compound is treated with aqueous ammonia and the resulting sulfonamide is then reacted with 30 % sodium methanolate. Such reactions are known and will be familiar to the person skilled in the art.

Preferred crystal modifications of the compounds of formula I may be prepared as follows:

For example, the J modification of the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is ^ΛA and s is 0 is prepared by adding a 5-25 % by weight solution of 4,6-dimethoxy-pyrimidine-2-isocyanate in anhydrous tetrahydrofuran at a temperature of 35-65°C to a 15-35 % by weight suspension of 3-(2-trifluoroethoxy)- pyridinyl-sulfonamide sodium salt in anhydrous tetrahydrofuran.

After the addition of the 4,6-dimethoxy-pyrimidine-2-isocyanate, the reaction mixture is stirred until the conversion is complete. This process is preferably carried out at a temperature of 40-50⁰C. The J modification so obtained can be separated from the reaction mixture by filtration.

The process for the preparation of the K modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 0 is carried out as follows: a 5-25 % by weight solution of 4,6-dimethoxy-pyrimidine-2-isocyanate in anhydrous tetrahydrofuran is added at a temperature of 35-65⁰C to a 15-35 % by weight suspension of 3-(2- trifluoroethoxy)-pyridinyl-sulfonamide sodium salt in anhydrous tetrahydrofuran, filtration is carried out and the filtration residue (J modification) is then dried at a temperature of 30-90°C and a pressure of from 1 to 10 kPa.

After the addition of the 4,6-dimethoxy-pyrimidine-2-isocyanate, the reaction mixture is stirred until the conversion is complete. For the drying, in this process variant a temperature of 40-60⁰C and a pressure of from 2 to 6 kPa is preferred.

The process for the preparation of the C modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 is carried out as follows: either the substantially amorphous form (A modification) is exposed to air of 98 % relative humidity, or water is added to the K modification in a ratio of water to K modification of from 0.1 : 1 to 0.4 : 1 , filtration is carried out and the filtration residue is then dried at a temperature of 30-90⁰C and a pressure of from 1 to 10 kPa.

For the preparation of the C modification, the ratio of water to K modification may vary from 0.1 : 1 to 0.4 : 1 ; a ratio of from 0.1 : 1 to 0.3 : 1 is especially preferred. The addition of water can take place at a temperature of 0-60⁰C, especially at a temperature of 5-40⁰C. The drying of the C modification is preferably carried out at a temperature of 40-60⁰C and a pressure of 2 to 6 kPa.

The C modification can advantageously also be prepared by adding N-[(4,6-dimethoxy- 2-pyrimidinyl)carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridine-2-sulfonamide to an aqueous sodium hydroxide solution, then concentrating by evaporation in vacuo at a temperature of 50°C, stirring the residue so obtained with diethyl ether, filtering, drying at temperatures of >120°C and then exposing the resulting substantially amorphous salt (A modification) to air of 98 % relative humidity.

The process for the preparation of the I modification of the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1 and s is 1 is carried out as follows: a 5-25 % by weight solution of 4,6-dimethoxy-pyrimidine-2-isocyanate in anhydrous tetrahydrofuran is added at a temperature of from 0 to 30⁰C to a 10-35 % by weight suspension of 3-(2-trifluoroethoxy)-pyridinylsulfonamide sodium salt in anhydrous tetrahydrofuran and then 1-20 molar equivalents of water relative to the 3-(2- trifluoroethoxy)-pyridinylsulfonamide sodium salt are added. In this variant the addition of 2-5 molar equivalents of water is especially preferred.

The process for the preparation of the B modification of the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 is carried out as follows: water is added to the compound of formula I wherein M is sodium, n is 1 and L, r and s are as defined for formula I in a ratio of water to the compound in question of from 0.5 : 1 to 20 : 1 , filtration is carried out and the filtration residue is dried at a temperature of 30-90⁰C and a pressure of from 1 to 10 kPa.

A preferred variant of the process for the preparation of the B modification is carried out as follows: water is added to the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 0 (K modification), or to the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1/2 and s is 0 (J modification), or to the compound of formula I wherein M is sodium, n is 1 , L is tetrahydrofuran, r is 1 and s is 1 (I modification), or to the compound of formula I wherein M is sodium, n is 1 , r is 0 and s is 1 (C modification), in a ratio of water to K, J, I or C modification of from 0.5 : 1 to 20 : 1 , filtration is carried out and the filtration residue is then dried at a temperature of 30-90⁰C and a pressure of from 1 to 1 O kPa.

The temperature for the addition of water can vary from 0 to 80⁰C; a temperature of 5- 4O⁰C is especially preferred. The drying of the filtration residue can be carried out at temperatures of 30-90°C and a pressure of from 1 to 10 kPa; a temperature of 40-60⁰C and a pressure of 2 to 6 kPa is preferred. It is especially advantageous to add seed crystals of the B modification to the suspension in order to accelerate the growth of crystals. The herbicidal synergistic composition according to the invention may have more than two active ingredients, but may not consist solely of pyriftalid, cinosulfuron, pretilachlor and trifloxysulfuron as the active ingredients. Preferably the herbicidal synergistic composition will consist of, as active ingredients, a compound of formula I, and pretilachlor or salt thereof.

The compound of formula I and pretilachlor may be used according to any aspect of the invention as described herein in any desired mixing ratio, usually with an excess of the one component over the other. Preferred mixing ratios between a compound of formula I and pretilachlor are from 1 :75 to 1 :300 and in particular, 1 :150.

The rate of application can vary within a wide range and depends on the nature of the soil, the type of application (pre- or post-emergence; seed dressing; application to the seed furrow; no tillage application), on the cultivated plant, the weed to be controlled, the prevailing climatic conditions and on other factors determined by the type of application, the time of application and the target crop. In general, a compound of formula I and pretilachlor may be used in combination according to any of the aspect of the invention described herein at a rate of application of from 0.001 to 10kg/ha, preferably from 0.1 to 1.5 kg/ha, more preferably from 0.25 to 1 kg/Ha and most preferably at about 0.3kg/ha (weight of combined active ingredient/ha).

It is extremely surprising that the combination of the active ingredient of formula I with pretilachlor surpasses the additive action on the weeds to be controlled that is to be expected in principle, and this broadens the range of action of both active ingredients in two respects. Firstly, the rates of application of the individual active ingredients

(compound of formula I and/or pretilachlor) may be reduced whilst still achieving a good level of herbicidal activity. Secondly, the composition of the invention achieves a high degree of weed control even in cases where the compounds individually, when used at low rates of application, have become no longer useful from an agronomic standpoint. The result of this is a considerable broadening of the weed spectrum and an additional increase in selectivity for crops of useful plants, as is necessary and desirable in case of inadvertent overdosage of the active ingredient. Furthermore, while maintaining outstanding control of weeds in crops of useful plants, the compositions of the invention permit a greater flexibility with regard to subsequent crops. In addition, the onset of action of the compound of formula I may be accelerated in the presence of pretilachlor. It is thus clear that herbicidal synergistic compositions and herbicidal formulations of the invention are extremely valuable in controlling undesired plant growth, like weeds (e.g. grasses and broad-leaf weeds) and/or volunteer crop plants, in crops of useful plants. Such control of undesired plant growth may non-selective, or preferably it will selective with respect to the crop of useful plants.

In a further aspect the invention thus provides a method of controlling undesired plant growth in a crop of useful plants, which comprises applying an herbicidal synergistic composition or herbicidal formulation as described herein to the crop or the area of cultivation thereof.

Areas under cultivation are to be understood as including land where the crop plants are already growing as well as land intended for the cultivation of those crop plants.

The compositions and formulations according to the invention are suitable for all methods of application typical in agriculture, such as pre-emergence application, post- emergence application and seed dressing.

Furthermore, in order to effect control of undesired plant growth, the combination of compound of formula I and pretilachlor can be applied simultaneously or sequentially, in any order, to wherever the control of undesired plant growth is needed.

Thus in a further aspect the invention provides a method of controlling undesired plant growth in a crop of useful plants, which comprises applying (i) a compound of formula I as defined above and (ii) pretilachlor, either simultaneously or separately in amounts sufficient to effect synergy between the herbicidal activity of the compound of formula I and pretilachlor, to said crop or the area of cultivation thereof.

The skilled man will appreciate that where a compound of formula I and pretilachlor are applied separately to said crop or area of cultivation thereof, the time elapse between application of each compound should be such that both compounds are able to act synergistically on the undesired vegetation.

The method of application of each active ingredient or composition/formulation of the invention to the crop plant or area of cultivation thereof, may be any method routinely used in agriculture, for example by spray or broadcast method typically after suitable dilution of said active ingredient/composition/formulation.

Crops of useful plants upon which herbicidal synergistic compositions and herbicidal formulations of the invention can be used, and to which methods of the invention may be applied include any crop of useful plants, and in particular crops of rice.

In a particularly preferred embodiment, compositions, formulations and/or methods of the invention are employed to achieve post-emergence control of undesired vegetation in rice.

The term "crops" is to be understood as also including crops that have been rendered tolerant to herbicides or classes of herbicides (for example ALS, GS, EPSPS, PPO and HPPD inhibitors) as a result of conventional methods of breeding or genetic engineering. An example of a crop that has been rendered tolerant e.g. to imid- azolinones, such as imazamox, by conventional methods of breeding is Clearfield® summer rape (Canola). Examples of crops that have been rendered tolerant to herbicides by genetic engineering methods include e.g. glyphosate- and glufosinate- resistant maize varieties commercially available under the trade names RoundupReady® and LibertyLink®.

Crops are also to be understood as being those which have been rendered resistant to harmful insects by genetic engineering methods, for example Bt maize (resistant to European corn borer), Bt cotton (resistant to cotton boll weevil) and also Bt potatoes (resistant to Colorado beetle). Examples of Bt maize are the Bt-176 maize hybrids of NK® (Syngenta Seeds). The Bt toxin is a protein that is formed naturally by Bacillus thuringiensis soil bacteria. Examples of toxins and transgenic plants able to synthesise such toxins are described in EP-A-451 878, EP-A-374 753, WO 93/07278, WO 95/34656, WO 03/052073 and EP-A-427 529. Examples of transgenic plants that contain one or more genes which code for an insecticidal resistance and express one or more toxins are KnockOut® (maize), Yield Gard® (maize), NuCOTIN33B® (cotton), Bollgard® (cotton), NewLeaf® (potatoes), NatureGard® and Protexcta®. Plant crops and their seed material can be resistant to herbicides and at the same time also to insect feeding ("stacked" transgenic events). Seed can, for example, have the ability to express an insecticidally active Cry3 protein and at the same time be glyphosate- tolerant. The term "crops" is to be understood as also including crops obtained as a result of conventional methods of breeding or genetic engineering which contain so- called output traits (e.g. improved flavour, storage stability, nutritional content).

Herbicidal synergistic compositions and herbicidal formulations of the invention can be used against a large number of agronomically important weeds. The weeds to be controlled may be both monocotyledonous and dicotyledonous weeds, such as, for example, Alisma spp, Leptochloa chinensis, Stellaria, Nasturtium, Agrostis, Digitaria, Avena, Setaria, Sinapis, Lolium, Solanum, Echinochloa and especially Echinochloa crus-galli or Echinochloa oryzicola, Scirpus and especially Scirpus juncoides, Monochoria and especially Monochoria vaginalis, Sagittaria and especially Sagittaria pygmea, Bromus, Alopecurus, Sorghum, Rottboellia, Cyperus and especially Cyperus iria, Abutilon, Sida, Xanthium, Amaranthus, Chenopodium, Ipomoea, Chrysanthemum, Galium, Viola, Veronica, and lschaemum spp. Compositions of the invention are particularly effective against Echinolchloa spp. and lschaemum spp. as shown herein in the Examples.

Compounds of formula I and pretilachlor can be used in unmodified form, i.e. as obtainable from synthesis, but preferably are formulated in any suitable manner using formulation adjuvants, such as carriers, solvents and surface-active substances, for example, as described hereinafter with respect to herbicidal formulations of the invention.

As described above, these active ingredients of a compound of formula I and pretilachlor may be employed separately and sequentially, or together as an herbicidal synergistic composition. When employed as a composition, each active ingredient may be as obtained from synthesis, or may be independently formulated and subsequently combined, or the compound of formula I and pretilachlor may be formulated together.

Thus in a further aspect the invention provides an herbicidal formulation comprising an herbicidal synergistic composition as described hereinbefore, and a formulation adjuvant.

Herbicidal formulations of the invention can be in various physical forms, for example in the form of dusting powders, gels, wettable powders, water-dispersible granules, water- dispersible tablets, effervescent compressed tablets, emulsifiable concentrates, micro- emulsifiable concentrates, oil-in-water emulsions, oil flowables, aqueous dispersions, oily dispersions, suspoemulsions, capsule suspensions, emulsifiable granules, soluble liquids, water-soluble concentrates (with water or a water-miscible organic solvent as carrier), impregnated polymer films or in other forms known, for example, from the Manual on Development and Use of FAO Specifications for Plant Protection Products, 5th Edition, 1999. Such formulations can either be used directly or are diluted prior to use. In certain embodiments, (e.g. where compounds of formula I are pre-mixed with pretilachlor) oil flowable or oily dispersions are the preferred types of formulation for use in the invention. Diluted formulations can be prepared, for example, with water, liquid fertilisers, micronutrients, biological organisms, oils, or suitable solvents.

Such formulations can be prepared, for example, by mixing the active ingredients with formulation adjuvants in order to obtain combinations in the form of finely divided solids, granules, solutions, dispersions or emulsions. The active ingredients can also be formulated with other adjuvants, for example finely divided solids, mineral oils, vegetable oils, modified vegetable oils, organic solvents, water, surface-active substances or combinations thereof. The active ingredients can also be contained in very fine microcapsules consisting of a polymer. Microcapsules contain the active ingredients in a porous carrier. This enables the active ingredients to be released into their surroundings in controlled amounts (e.g. slow release). Microcapsules usually have a diameter of from 0.1 to 500 microns. They contain active ingredients in an amount of about from 25 to 95 % by weight of the capsule weight. The active ingredients can be present in the form of a monolithic solid, in the form of fine particles in solid or liquid dispersion or in the form of a suitable solution. The encapsulating membranes comprise, for example, natural and synthetic gums, cellulose, styrene-butadiene copolymers, polyacrylonitrile, polyacrylate, polyester, polyamides, polyureas, polyurethane or chemically modified polymers and starch xanthates or other polymers that are known to the person skilled in the art in this connection. Alternatively it is possible for very fine microcapsules to be formed wherein the active ingredient is present in the form of finely divided particles in a solid matrix of a base substance, but in that case the microcapsule is not encapsulated.

The formulation adjuvants suitable for use in the invention are known per se. As liquid carriers there may be used: water, toluene, xylene, petroleum ether, vegetable oils, acetone, methyl ethyl ketone, cyclohexanone, acid anhydrides, acetonitrile, acetophenone, amyl acetate, 2-butanone, butylne carbonate, chlorobenzene, cyclo- hexane, cyclohexanol, alkyl esters of acetic acid, diacetone alcohol, 1 ,2- dichloropropane, diethanolamine, p-diethylbenzene, diethylene glycol, diethylene glycol abietate, diethylene glycol butyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ether, N,N-dimethylformamide, dimethyl sulfoxide, 1 ,4-dioxane, dipropylene glycol, dipropylene glycol methyl ether, dipropylene glycol dibenzoate, diproxitol, alkylpyrrolidone, ethyl acetate, 2-ethyl hexanol, ethylene carbonate, 1 ,1 ,1- trichloroethane, 2-heptanone, alpha-pinene, d-limonene, ethyl lactate, ethylene glycol, ethylene glycol butyl ether, ethylene glycol methyl ether, gamma-butyrolactone, glycerol, glycerol acetate, glycerol diacetate, glycerol triacetate, hexadecane, hexylene glycol, isoamyl acetate, isobornyl acetate, isooctane, isophorone, isopropylbenzene, isopropyl myristate, lactic acid, laurylamine, mesityl oxide, methoxypropanol, methyl isoamyl ketone, methyl isobutyl ketone, methyl laurate, methyl octanoate, methyl oleate, methylene chloride, m-xylene, n-hexane, n-octylamine, octadecanoic acid, octylamine acetate, oleic acid, oleylamine, o-xylene, phenol, polyethylene glycol (PEG 400), propionic acid, propyl lactate, propylene carbonate, propylene glycol, propylene glycol methyl ether, p-xylene, toluene, triethyl phosphate, triethylene glycol, xylenesulfonic acid, paraffin, mineral oil, trichloroethylene, perchloroethylene, ethyl acetate, amyl acetate, butyl acetate, propylene glycol methyl ether, diethylene glycol methyl ether, methanol, ethanol, isopropanol, and higher molecular weight alcohols, such as amyl alcohol, tetrahydrofurfuryl alcohol, hexanol, octanol, ethylene glycol, propylene glycol, glycerol, N-methyl-2-pyrrolidone and the like. Water is generally the carrier of choice for the dilution of the concentrates. Suitable solid carriers are, for example, talc, titanium dioxide, pyrophyllite clay, silica, attapulgite clay, kieselguhr, limestone, calcium carbonate, bentonite, calcium montomorillonite, cottonseed husks, wheatmeal, soybean flour, pumice, wood flour, ground walnut shells, lignin and similar materials, as described, for example, in CFR 180.1001. (c) & (d).

A large number of surface-active substances can advantageously be used both in solid and in liquid formulations of the invention, especially in those formulations which can be diluted with a carrier prior to use. Surface-active substances may be anionic, cationic, non-ionic or polymeric and they may be used as emulsifiying, wetting or suspending agents or for other purposes. Typical surface-active substances include, for example, salts of alkyl sulfates, such as diethanolammonium lauryl sulfate; salts of alkylarylsulfonates, such as calcium dodecylbenzenesulfonate; alkylphenol-alkylene oxide addition products, such as nonylphenol ethoxylate; alcohol-alkylene oxide addition products, such as tridecyl alcohol ethoxylate; soaps, such as sodium stearate; salts of alkylnaphthalenesulfonat.es, such as sodium dibutylnaphthalenesulfonate; dialkyl esters of sulfosuccinate salts, such as sodium di(2-ethylhexyl)sulfosuccinate; sorbitol esters, such as sorbitol oleate; quaternary amines, such as lauryl trimethylammonium chloride, polyethylene glycol esters of fatty acids, such as polyethylene glycol stearate; block copolymers of ethylene oxide and propylene oxide; and salts of mono- and di-alkyl phosphate esters; and also further substances described e.g. in "McCutcheon's Detergents and Emulsifiers Annual", MC Publishing Corp., Ridgewood, New Jersey, 1981.

Further adjuvants which can usually be used in pesticidal formulations, and may thus be employed in the present invention, include crystallisation inhibitors, viscosity-modifying substances, suspending agents, dyes, anti-oxidants, foaming agents, light absorbers, mixing aids, anti-foams, complexing agents, neutralising or pH-modifying substances and buffers, corrosion-inhibitors, fragrances, wetting agents, absorption improvers, micronutrients, plasticisers, glidants, lubricants, dispersants, thickeners, anti-freezes, microbiocides and also liquid and solid fertilisers.

Herbicidal formulations of the invention may also comprise additional active substances, for example further herbicides, herbicide safeners, plant growth regulators, fungicides or insecticides.

Herbicidal formulations according to the invention may additionally include an additive comprising an oil of vegetable or animal origin, a mineral oil, alkyl esters of such oils or mixtures of such oils and oil derivatives. The amount of oil additive used in the combination according to the invention is generally from 0.01 to 10 %, based on the spray mixture. For example, the oil additive can be added to the spray tank in the desired concentration after the spray mixture has been prepared. Preferred oil additives comprise mineral oils or an oil of vegetable origin, for example rapeseed oil, olive oil or sunflower oil, emulsified vegetable oil, such as AMIGO® (Rhδne-Poulenc Canada Inc.), alkyl esters of oils of vegetable origin, for example the methyl derivatives, or an oil of animal origin, such as fish oil or beef tallow. A preferred additive contains, for example, as active components essentially 80 % by weight alkyl esters of fish oils and 15 % by weight methylated rapeseed oil, and also 5 % by weight of customary emulsifiers and pH modifiers. Especially preferred oil additives comprise alkyl esters of C₈-C₂₂ fatty acids, especially the methyl derivatives of C₁₂-C₁₈ fatty acids, for example, the methyl esters of lauric acid, palmitic acid and oleic acid, being important; those esters are known as methyl laurate (CAS-11 1-82-0), methyl palmitate (CAS-112-39-0) and methyl oleate (CAS-112-62-9) respectively. A preferred fatty acid methyl ester derivative is Emery® 2230 or 2231 (Cognis GmbH). Those and other oil derivatives are also known from the Compendium of Herbicide Adjuvants, 5th Edition, Southern Illinois University, 2000.

The application and action of the oil additives can be further improved by combining them with surface-active substances, such as non-ionic, anionic or cationic surfactants. Examples of suitable anionic, non-ionic and cationic surfactants are listed on pages 7 and 8 of WO 97/34485. Preferred surface-active substances are anionic surfactants of the dodecylbenzylsulfonate type, especially the calcium salts thereof, and also non-ionic surfactants of the fatty alcohol ethoxylate type. Special preference is given to ethoxylated C₁₂-C₂₂ fatty alcohols having a degree of ethoxylation of from 5 to 40. Examples of commercially available surfactants are the Genapol types (Clariant AG). Also preferred are silicone surfactants, especially polyalkyl-oxide-modified heptamethyltrisiloxanes, which are commercially available e.g. as Silwet L-77®, and also perfluorinated surfactants. The concentration of surface-active substances in relation to the total additive is generally from 1 to 30 % by weight. Examples of oil additives that consist of mixtures of oils or mineral oils or derivatives thereof with surfactants are Edenor ME SU®, Turbocharge® (Syngenta AG, CH) and Actipron® (BP Oil UK Limited, GB).

The said surface-active substances may also be used in the formulations alone, that is to say without oil additives.

Furthermore, the addition of an organic solvent to the oil additive/surfactant mixture can contribute to a further enhancement of action. Suitable solvents are, for example, Solvesso® (ESSO) and Aromatic Solvent® (Exxon Corporation). The concentration of such solvents can be from 10 to 80 % by weight of the total weight. Such oil additives, which may be in admixture with solvents, are described, for example, in US-A- 4 834 908. A commercially available oil additive disclosed therein is known by the name MERGE® (BASF Corporation). A further oil additive that is preferred according to the invention is SCORE® (Syngenta Crop Protection Canada.)

In addition to the oil additives listed above, in order to enhance the activity of the combinations according to the invention it is also possible for formulations of alkylpyrrolidones, (e.g. Agrimax®) to be added to the spray mixture. Formulations of synthetic latices, such as, for example, polyacrylamide, polyvinyl compounds or poly-1- p-menthene (e.g. Bond®, Courier® or Emerald®) can also be used. Solutions that contain propionic acid, for example Eurogkem Pen-e-trate®, can also be mixed into the spray mixture as activity-enhancing agents.

The herbicidal formulations of the invention generally contain from 0.1 to 99 % by weight, especially from 0.1 to 95 % by weight, of an active ingredient mixture of the combinations according to the invention and from 1 to 99.9 % by weight of formulation adjuvant. In a preferred embodiment the formulation adjuvant comprises an oil. In further preferred embodiments, herbicidal formulations of the invention preferably include from 0 to 25 % by weight of a surface-active substance. Whereas commercial products will preferably be formulated as concentrates, the end user will normally employ dilute formulations. The present invention extends to such dilute formulations as well as to their use as described herein.

Examples of some preferred herbicidal formulations of the invention are described below:

(% = percent by weight; "active ingredient mixture" denotes a mixture of compound of formula I and pretilachlor as described hereinbefore):

Emulsifiable concentrates: active ingredient mixture: 1 to 95 %, preferably 60 to 90 % surface-active agent: 1 to 30 %, preferably 5 to 20 % liquid carrier: balance

Dusts: active ingredient mixture: 0.1 to 10 %, preferably 0.1 to 5 % solid carrier: 99.9 to 90 %, preferably 99.9 to 99 %

Suspension concentrates: a) aqueous active ingredient mixture: 5 to 75 %, preferably 10 to 50 % surface-active agent: 1 to 40 %, preferably 2 to 30 % water: balance b) oil-based active ingredient mixture: 5 to 75 %, preferably 10 to 50 % surface-active agent: 1 to 40 %, preferably 2 to 30 % oil: balance

Wettable powders: active ingredient mixture: 0.5 to 90 %, preferably 1 to 80 % surface-active agent: 0.5 to 20 %, preferably 1 to 15 % solid carrier: balance

Granules: active ingredient mixture: 0.1 to 30 %, preferably 0.5 to 15 % solid carrier: 99.9 to 70 %, preferably 99,5 to 85 %

FORMULATION EXAMPLES

The following examples are intended to further illustrate, but not limit, the invention.

F1. Emulsifiable concentrates a) b) c) d) active ingredient mixture 5 % 10 % 25 % 50 % calcium dodecylbenzene- sulfonate 6 % 8 % 6 % 8 % castor oil polyglycol ether 4 % - 4 % 4 %

(36 mol of ethylene oxide) octylphenol polyglycol ether - 4 % - 2 % (7-8 mol of ethylene oxide)

NMP - - 10 % 20% arom. hydrocarbon 85 % 78 % 55 % 16% mixture C₉-C₁₂

Emulsions of any desired concentration can be prepared from such concentrates by dilution with water.

F2. Solutions a) b) c) d) active ingredient mixture 5 % 10 % 50 % 90 % 1-methoxy-3-(3-methoxy- propoxy)-propane - 20 % 20 % polyethylene glycol MW 400 20 % 10 %

NMP 30 % 10% arom. hydrocarbon 75 % 60 % mixture C₉-C₁₂

The solutions are suitable for application in the form of microdrops.

F3. Wettable powders a) b) c) d) active ingredient mixture 5 % 25 % 50 % 80 % sodium lignosulfonate 4 % - 3 % - sodium lauryl sulfate 2 % 3 % - 4 % sodium diisobutylnaphthalene- sulfonate - 6 % 5 % 6 % octylphenol polyglycol ether - 1 % 2 % - (7-8 mol of ethylene oxide) highly disperse silicic acid 1 % 3 % 5 % 10 % kaolin 88 % 62 % 35 %

The active ingredient is thoroughly mixed with the adjuvants and the mixture is thoroughly ground in a suitable mill, yielding wettable powders which can be diluted with water to give suspensions of any desired concentration.

F4. Coated qranules a) b) c) active ingredient mixture 0.1 % 5 % 15 % highly disperse silicic acid 0.9 % 2 % 2 % inorg. carrier 99.0 % 93 % 83 %

(diameter 0.1 - 1 mm) e.g. CaCO₃ or SiO₂

The active ingredient is dissolved in methylene chloride, the solution is sprayed onto the carrier and the solvent is subsequently evaporated off in vacuo.

F5. Coated αranules a) b) c) active ingredient mixture 0.1 % 5 % 15 % polyethylene glycol MW 200 1.0 % 2 % 3 % highly disperse silicic acid 0.9 % 1 % 2 % inorg. carrier 98.0 % 92% 80% (diameter 0.1 - 1 mm) e.g. CaCO₃ or SiO₂

The finely ground active ingredient is applied uniformly, in a mixer, to the carrier moistened with polyethylene glycol. Non-dusty coated granules are obtained in this manner.

F6. Extruder qranules a) b) c) d) active ingredient mixture 0.1 % 3% 5 % 15 % sodium lignosulfonate 1.5 % 2% 3 % 4 % carboxymethylcellulose 1.4 % 2% 2 % 2 % kaolin 97. 0% 93% 90 % 79 %

The active ingredient is mixed and ground with the adjuvants and the mixture is moistened with water. The resulting mixture is extruded and then dried in a stream of air.

F7. Dusts a) b) c) active ingredient mixture 0.1 % 1 % 5% talcum 39.9 % 49% 35% kaolin 60.0 % 50% 60%

Ready-to-use dusts are obtained by mixing the active ingredient with the carriers and grinding the mixture in a suitable mill.

F8. Suspension concentrates a) b) c) d) active ingredient mixture 3 % 10% 25% 50% ethylene glycol 5 % 5% 5% 5% nonylphenol polyglycol ether - 1 % 2% -

(15 mol of ethylene oxide) sodium lignosulfonate 3 % 3% 4% 5% carboxymethylcellulose 1 % 1 % 1 % 1 %

37 % aqueous formaldehyde 0 .2% 0.2 % 0.2 % 0.2 % solution silicone oil emulsion 0. 8% 0.8 % 0.8 % 0.8 % water 87 % 79 % 62 % 38 %

The finely ground active ingredient is intimately mixed with the adjuvants, yielding a suspension concentrate from which suspensions of any desired concentration can be prepared by dilution with water.

Whilst the desired synergistic effect between a compound of formula I and pretilachlor may be achieved through (i) the application of one of these active ingredients followed by the other (preferably with each being formulated) or (ii) separate active ingredients (again, preferably formulated) applied simultaneously, it is often more practical for the active ingredients to be formulated separately and to be brought together in the desired mixing ratio in the applicator in the form of a "tank mixture" in water shortly before application and this forms yet another aspect of the invention. In yet a further aspect, the active ingredients will be in the form of a pre-mix combination wherein the compound of formula I and pretilachlor are formulated together. Preferably such an herbicidal formulation will be an oil-based formulation.

BIOLOGICAL EXAMPLES

A synergistic effect exists whenever the action of, for example, the active ingredient combination of the compounds according to the combinations of the instant invention is greater than the sum of the actions of the active ingredients applied separately.

The herbicidal action to be expected, We, for a given combination of two herbicides (I) and (II) can be calculated as follows (see COLBY, S.R., "Calculating synergistic and antagonistic response of herbicide combinations", Weeds 15, pages 20-22, 1967):

We = X + [Y» (l00- X) / l00]

wherein:

X = percentage herbicidal action on treatment with compound (I) at a rate of application of p kg per hectare, compared with the untreated control (= 0 %).

Y = percentage herbicidal action on treatment with a compound (II) at a rate of application of q kg per hectare, compared with the untreated control.

Thus, if the observed activity is greater than that the expected from the Colby formula, then synergism is present.

Example B1 : Pre-emerqence test:

The test plants (weeds) are sown in seed trays under greenhouse conditions. A standard soil is used as cultivation substrate. At a pre-emergence stage, the herbicides, both alone and in admixture, are applied to the surface of the soil. The rates of application are governed by the optimum concentrations determined under field or greenhouse conditions. The tests are evaluated 2 to 4 weeks later (100 % = plant is completely dead; 0 % = no phytotoxic action on the plant).

Example B2: Early post-emergence herbicidal action:

The field tests were carried out in water-saturated ground standing under about 5 cm of water (saturated conditions). Test crop plants were rice, and variety was Oryza sativa L indica - IR-64.

At an early post-emergence stage (2- to 3-leaf stage), the herbicides, both on their own and in admixture, are applied to the test plants under water-saturated ground conditions using a foliar spray at 2272l/ha. The rates of application depend on the optimum concentrations ascertained under field conditions. The tests are evaluated after 21 days (100 % action = plant is completely dead; 0 % action = no phytotoxic action) for activity against Echinochloa spp and lschaemum spp. The results are shown below in Tables B1 and B2.

Table B1 : Early post-emergence herbicidal action of the combination according to the invention comprising trifloxysulfuron-sodium and pretilachlor at 21 days after application (21 DAA):

Table B2: Early post-emergence herbicidal action of the combination according to the invention comprising trifloxysulfuron-sodium and pretilachlor at 21 days after application (21 DAA):

Claims

1. An herbicidal synergistic composition comprising as active ingredients a mixture of (i) a compound of formula I

wherein

M is an alkali metal or alkaline earth metal; n is 1 or 2; r and s are each independently of the other O₁ J4, 1 , 1 V≥_t 2, 2^Λ/≥ or 3; and

L is ethyl acetate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, acetone, butanone, methylene chloride, trichloromethane, trichloroethane, tetrahydrofuran, diethyl ether, 1 ,2- dimethoxyethane, dioxane, methyl tert-butyl ether, chlorobenzene, toluene or xylene; and

(ii) a synergistically effective amount of pretilachlor, or salt thereof, with the proviso that said herbicidal synergistic composition does not consist of as active ingredients: pyriftalid, cinosulfuron, pretilachlor and trifloxysulfuron.

2. An herbicidal synergistic composition consisting of as active ingredients a mixture of (i) a compound of formula I as defined in claim 1 and (ii) a synergistically effective amount of pretilachlor.

The herbicidal synergistic composition according to claim 1 or claim 2, wherein M is Na, n is 1 , r is 0, s is 0.

4. The herbicidal synergistic composition according to claim 1 or claim 2, wherein M is Na, n is 1 , r is 0, s is 1.

5. The herbicidal synergistic composition according to any one of the preceding claims, wherein the ratio of the compound of formula I to pretilachlor is in the range of 1 :75 to 1 :300.

6. An herbicidal formulation comprising an herbicidal synergistic composition as defined in any one of the preceding claims, and a formulation adjuvant.

7. The herbicidal formulation according to claim 6, which is formulated as an oil- based formulation.

8. The herbicidal formulation according to claim 6 or claim 7, which is diluted with an agriculturally acceptable diluent.

9. A method of controlling undesired plant growth in a crop of useful plants, which comprises applying an herbicidal synergistic composition as defined in any one of the previous claims, to the crop or the area of cultivation thereof.

10. The method according to claim 9, wherein said herbicidal composition is applied at a rate of from 0.001 to 10kg of active ingredient per hectare.

11. A method of controlling undesired plant growth in a crop of useful plants, which comprises applying (i) a compound of formula I as defined in claim 1 and (ii) pretilachlor, either simultaneously or separately in amounts sufficient to effect synergy between the herbicidal activity of the compound of formula I and pretilachlor, to said crop or the area of cultivation thereof.

12. The method according to claim 11 , wherein the ratio of the compound of formula

I to pretilachlor which is applied to said crop or the area of cultivation thereof is in the range 1 :75 to 1 :300.

13. The method according to claim 12, wherein said ratio is 1 :150.

14. The method according to any one of claims 9 to 13, wherein the crop is rice.

15. Use of a compound of formula I as defined in claim 1 to enhance in a synergistic manner the herbicidal activity of a composition comprising pretilachlor or a salt thereof.

16. Use of pretilachlor or a salt thereof to enhance in a synergistic manner the herbicidal activity of a composition comprising a compound of formula I as defined in claim 1.