The present invention relates to an improved agrochemical formulation. More specifically, the present invention relates to a solid controlled release agrochemical formulation. In a preferred embodiment the agrochemical formulation is a herbicidal formulation, more preferably one which comprises a /7-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor. The present invention further relates to a method of controlling undesirable vegetation at a locus using said formulation. The protection of crops from weeds and other vegetation that inhibits 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. Commercial herbicides and some that are still in development are described in The Pesticide Manual, 12 ^th edition, published in 2000 by the British Crop Protection Council.

Many herbicides also damage crop plants. The control of weeds in a growing crop therefore requires the use of so-called 'selective' herbicides, which are chosen to kill the weeds while leaving the crop undamaged. In practice, few herbicides are fully selective, in that they will kill all the weeds and leave the crop untouched at a particular application rate. The use of most selective herbicides is actually a balance between applying enough herbicide to acceptably control most of the weeds and causing only minimal crop damage. One known selective herbicide is mesotrione, 2-(4-methylsulphonyl-2- nitrobenzoyl)cyclohexane-l ,3-dione, an HPPD inhibitor. Mesotrione is usually formulated for sale as a concentrated suspension of solid mesotrione in water. The concentrate typically contains between 100 and 500g/l of mesotrione. This concentrate is then diluted by the end user, shortly before application, to give a final ready-to-use composition that typically comprises between 1 and lOg/1 of mesotrione.

However, for certain applications, solid herbicidal formulations are preferred. For example, solid formulations - especially granules - can be particularly useful in respect of paddy field applications, where the end-user can apply the herbicide containing granule directly to the paddy field water, wherein the herbicide is subsequently released from the granule in order to provide the necessary weed control.

Solid formulations comprising mesotrione and their use to control weeds in turf have been reported - see WO2007/011847. Furthermore, the use of HPPD inhibitors to control weeds in rice grown in paddy fields is known - see for example WO91/05470 and WO2006/105873. However, one problem associated with granule formulations of HPPD inhibitors - especially to control weeds in rice and especially when grown in a paddy field environment is that it is very difficult to control the release of the active ingredient from the granule in order to confer optimal weed control. With regard to the reported granule formulations the HPPD inhibitor is released from the formulation too fast, which consequently results in far lower herbicidal efficacy than expected. Thus there remains a need to provide a solid formulation which provides slower release of the active ingredient(s).

Thus according to the present invention there is provided an improved solid agrochemical formulation comprising:-

(a) an agrochemical having a pKa from 2 to 7;

(b) a water-soluble aluminium salt; and

(c) a silicate mineral.

The term agrochemical includes, for example, insecticides, fungicides (e.g pyroquilon), herbicides and plant growth regulators (e.g trinexapac-ethyl). It should be understood that many agrochemicals having a pKa from 2 to 7 have potential utility with regard to the controlled release formulation of the present invention. In an especially preferred embodiment, the agrochemical is a herbicide - more preferably one selected from the group consisting of a HPPD inhibitor, glyphosate (including salts therefore and in particular the potassium salt) and a sulphonylurea herbicide (especially bensulfuron- methyl).

In a preferred embodiment of the invention, the herbicide is a HPPD inhibitor is selected from the group consisting of isoxazoles, triketones, pyrazoles, benzobicyclon and ketospiradox. In a preferred embodiment, the isoxazole is a compound of formula (IA)

wherein:

R is hydrogen or -CO ₂ R ; R ¹ is C _L4 alkyl or C _3-6 cycloalkyl optionally substituted by Ci _-6 alkyl;

R ² is independently selected from the group consisting of halogen, nitro, cyano, amino, Ci _-4 alkyl, Ci _-4 haloalkyl, Ci _-6 alkoxy, Ci _-6 alkoxy-Ci- ₆ alkyl, Ci _-6 alkoxy-

C _2-6 alkoxy, C] _-6 alkoxy-C _2-6 -alkoxy-Ci _-6 alkyl, Ci _-4 haloalkoxy, Ci _-4 haloalkoxy-

Ci _-4 alkyl, -(CR ⁴ R ⁵ ) _c S(O) _b R ⁶ , -S(O) _b R ⁶ , -OSO ₂ R ⁶ and -N(R ⁷ )SO ₂ R ⁶ ; R ³ is Ci _-4 alkyl;

R ⁴ and R ⁵ are independently hydrogen or Ci _-4 alkyl;

R ⁶ is C _M alkyl;

R ⁷ is hydrogen or C] _-6 alkyl; a is one, two or three; b is zero, one or two; and c is one or two (where c is two, the groups (CR ⁴ R ⁵ ) may be the same or different).

In a preferred embodiment R is hydrogen; R ¹ is cyclopropyl; R ² is halogen (preferably chloro), or Ci _-4 haloalkyl (preferably trifluorom ethyl); and a is two.

Particularly preferred compounds of formula (IA) include 5-cyclopropyl-4-(2- methylsulfonyl-4-trifluoromethyl)benzoylisoxazole (isoxaflutole) and 4-(2-chloro-4- methylsulphonyl)benzoyl-5-cyclopropylisoxazole (isoxachlortole), especially isoxaflutole. In a preferred embodiment, the triketone is a 2 -benzoyl- 1 ,3-cyclohexanedione of formula (IB),

(IB) wherein:

R ⁸ is selected from the group consisting of halogen, nitro, Ci _-4 alkyl, Ci _-4 haloalkyl, Ci _-6 alkoxy, Ci _-6 alkoxy-Ci _-6 alkyl, Ci _-6 alkoxy-C _2-6 alkoxy, Ci _-6 alkoxy-C _2-6 -alkoxy-Ci _-6 alkyl, Ci _-4 haloalkoxy and Ci _-4 haloalkoxy-Ci _-4 alkyl.

Preferably, R ⁸ is chloro or nitro.

With regard to compounds of formula (IB) R ² is preferably selected from the group consisting Of -SO ₂ CH ₃ , CF ₃ and 2,2,2 trifluoroethoxymethyl.

Preferred compounds of formula (IB) are 2-(2'-nitro-4'- methylsulphonylbenzoyl)-l,3-cyclohexanedione (mesotrione), 2-(2'-nitro-4'- methylsulphonyloxybenzoyl)-l,3-cyclohexanedione, 2-(2'-chloro-4'- methylsulphonylbenzoyl)-l ,3-cyclohexanedione (sulcotrione), 2-[2-chloro-4- (methylsuphonyl)-3-[2,2,2-trifluoroethoxy]methyl]benzoyl]-l, 3-cyclohexanedione (tembotrione), 4,4-dimethyl-2-(4-methanesulphonyl-2-nitrobenzoyl)-l,3- cyclohexanedione, 2-(2-chloro-3-ethoxy-4- methanesulphonylbenzoyl)-5-methyl-l ,3- cyclohexanedione and 2-(2-chloro-3-ethoxy-4-ethanesulphonylbenzoyl)-5-methyl- 1 ,3- cyclohexanedione

The triketone may also be of formula (IC)

With regard to compounds of formula (IC) R ² is preferably selected from the group consisting of -SO ₂ CH ₃ , CF ₃ and methoxyethoxymethyl.

In a particularly preferred embodiment the triketone of formula (IC) is 4- Hydroxy-3-[2-(2-methoxyethoxymethyl)-6-trifluoromethylpyridi ne-3-carbonyl]- bicyclo[3.2.1 ]oct-3-en-2-one).

Suitably, the pyrazole is a compound of formula (ID) wherein:

R ⁹ and R ¹⁰ are each independently selected from the group consisting of hydrogen, halo and Ci _-4 alkyl;

With regard to compounds of formula (ID) R ² is preferably selected from the group consisting of methyl, -SO ₂ CH ₃ and CF ₃ .

In a particularly preferred embodiment the pyrazole of formula (ID) is 5- hydroxyl- 1 ,3-dimethyl- 1 H-pyrazol-4-yl)[2-(methylsulfonyl)-4- 'i(trifluoromethyl)phenyl]methanone (pyrasulfotole).

Further examples of pyrazoles are compounds of formula (IE)

wherein:

R ¹¹ is Ci _-2 alkyl or chloro; R ¹² is hydrogen or Ci _-4 alkyl; and R ¹³ is C _{1 -4} alkyl.

In a preferred embodiment the pyrazole of compound (IE) is [3-(4,5-dihydro-3- isoxazolyl)-2-methyl-4-(methylsulfonyl)phenyl](5-hydroxy-l -methyl- lH-pyrazol-4- yl)methanone (topramesone).

Benzobicyclon is a compound of formula (IF)

Ketospiradox is a compound of formula (IG)

In a preferred embodiment of the present invention the HPPD-inhibiting herbicide is selected from the group consisting of mesotrione, sulcotrione, tembotrione, 4- Hydroxy-3-[2-(2-methoxyethoxymethyl)-6-trifluoromethylpyridi ne-3-carbonyl]- bicyclo[3.2.1]oct-3-en-2-one), isoxaflutole and pyrasulfotole. Particularly preferred is wherein the HPPD-inhibiting herbicide is mesotrione.

It should be understood that reference to the HPPD inhibitors above also includes, for example, reference to tautomers and agriculturally acceptable salts thereof. Examples of agriculturally acceptable salts include alkali metal salts such as sodium or potassium, alkaline earth metal salts such as magnesium or calcium, amine salts such as a monomethyl amine, dimethylamine, tri ethyl amine, ammonium salts or dimethyl ammonium salts. The herbicide may also be provided as a metal chelate. Metal ions which may be useful in forming the metal chelate include di- and trivalent transition metal ions such as Cu ²⁺ , Zn ²⁺ , Co ²⁺ , Fe ²⁺ , Ni ²⁺ and Fe ³⁺ . Examples of water-soluble aluminium salts include, for example, aluminium sulphate, poly aluminium chloride, aluminium silicate, aluminium chloride, aluminium nitrate, sodium aluminate and ammonium aluminium sulphate. Aluminium sulphate and basic aluminium chloride are particularly preferred.

The term "silicate mineral" is taken to mean a silicate-based inorganic substance having adsorptive property or capable of ion exchanging, e.g. bentonite, montmorilonite, zeolite, sepiolite, pyrophilite, kaolinite, talc and hydrotalcite. Bentonite and montmorilonite are particularly preferred. Suitably, the weight ratio of the HPPD inhibitor: silicate mineral in the formulation of the present invention is from 1%: 5% to 1%: 95% w/w and preferably from 1%: 10% to 1%: 70% w/w - more preferably from l%:10% to 1%: 60% w/w.

Suitably, the formulation comprises from 0.1% to 10% w/w of HPPD inhibitor. Suitably, the formulation of the present invention comprises from 1% to 20% w/w of water-soluble aluminium salt preferably from 2% to 10% w/w.

Suitably, the formulation comprises from 5% to 95% w/w of silicate mineral, preferably 10% to 70% w/w. All percentages are expressed as a proportion of the total solid formulation.

In a further embodiment of the method, the herbicidal formulation may further comprise or may be applied in combination with one or more additional active ingredients. Such additional active ingredients include herbicides, fungicides, insecticides and the like. Examples of herbicides include, but are not limited to, Bensulfuron methyl, CNP, Naproanilide, Bifenox, Pyributicarb, Bromobutide, Mefenacet, Daimuron, Imazosulfuron, Pyrazosulfuron ethyl, Simetryn, Prometryn, Dimethametryn, Chlomethoxynil, Oxadiazon, Pyrazolate, Pyrazoxyfen, Clomeprop, Benzofenap,

Thenylchlor, Oxaziclomefone, Pentoxazone, Cafenstrol, Azimsulfuron, Pyriminobac methyl, Fentrazamide, Bispyribac sodium, pretilachlor, metolachlor, Prodiamine, Esprocarb, Prosulfocarb, Triclopyr, Fluazifop, Obencarb, Molinate, Dimetinamide, Pelargonic acid, Dalapon, Piperophos, Butamiphos, Glyphosate, Sethoxydim, Clethodim, S-metolachlor, Cinmethylin, TH-547z: l-(2-chloro-6-«-propylimidazo[l,2-b]pyridadin- 3-ylsulfonyl)-3-(4,6-dimethoxypyrimidin-2-yl)urea, NC-620: 3-chloro-4-(5,6-dihydro-5- methyl- 1 ,4,2-dioxadin-3-yl)-N-[[(4,6-dimethoxy-2-pyrimidinyl)amino)c arbonyl]- 1 - methyl- lH-pyrazol-5-sulfonamide and ΗOK-201 : 1 -(2,4-dichlorophenyl)-N-(2,4- difluorophenyl)-l,5-dihydro-N-(l-methylethyl)-5-oxo-4H-l,2,4 -triazol-4-carboxamide . Examples of insecticides include, but are not limited to Cyanophos, Fenthion, Fenitrothion, Dichlofenthion, Primiphos-methyl, Diazinon, Isoxathion, Oxydeprofos, Marathion, Phenthoate, Formothion, Thiometon, Disulfoton, Prothiophos, Sulprofos, Propenofos, Pyraclofos, Dichlorvos, Naled, Chlorfenvinphos, Propaphos, Isofenphos, Etion, Carbosulfan, Benfuracarb, Allethrin, Permethrin, Cyhalothrin, Cyfluthrin, Fenvalerate, Flucythrinate, Fluvalinate, Cycloprothrin, Silafluofen, Propargite, Halfenprox, Ethoprophos and Fosthiazate. Examples of fungicides include, but are not limited to, Cyprodinil, Mepanipyrim, Pyrimethanil, Metalaxyl, Mepronil, Flutolanil, Tecloftalam, Pencycuron, Diclomezine, Triflumizole, Kasugamycin, Validamycin, Probenazole, Isoprothiolane, Cyproconazole, Metconazole, Tricyclazole, Pyroquilon, Oxolinic acid, Ferimzone, Iprodione, Triforine, Picoxystrobin, Azoxystrobin, Kresoxim- methyl, Orysastrobin, Pyraclostrobin, Trifloxystrobin, Metominostrobin, Calcium polysulfide, Ediphenfos, Propiconazole, Pefurazoate, Pyrifenox, Tetreconazloe, Echlomezole, Dinocap, and Metalaxyl-M. The skilled person will further appreciate that the solid herbicidal formulation of the present invention may further comprise various adjuvants and carriers known to or used in the industry for facilitating dispersion. The choice of formulation and mode of application for any given compound may affect its activity, and selection will be made accordingly. For example, the solid herbicidal formulation of this invention may be a dustable powder, a wettable powder, a granule, a water dispersible granule, a water- dispersable or water-foaming tablet, a briquette or other solid forms known in the art. The formulations are prepared by admixing the active ingredients with adjuvants including diluents, extenders, carriers, and conditioning agents to provide formulations in the form of finely-divided particulate solids, granules and pellets. Suitable agricultural adjuvants and carriers that are useful in preparing the formulations of the invention are well known to those skilled in the art.

Suitable solid carriers include talc, titanium dioxide, pyrophyllite clay, kaolin clay, silica, attapulgite clay, kieselguhr, chalk, diatomaceous earth, lime, calcium carbonate, bentonite clay, Fuller's earth, cotton seed hulls, wheat flour, soybean flour, pumice, wood flour, walnut shell flour, lignin, and the like.

A broad range of surface-active agents are advantageously employed in both solid and liquid formulations, especially those designed to be diluted with carrier before application. The surface-active agents can be anionic, cationic, nonionic or polymeric in character and can be employed as emulsifying agents, wetting agents, suspending agents, or for other purposes. Typical surface active agents include salts of alkyl sulfates, such as diethanolammonium lauryl sulfate; alkylarylsulfonate salts, such as calcium dodecylbenzenesulfonate; alkylphenol-alkylene oxide addition products, such as nonylphenol-C.sub.18 ethoxylate; alcohol-alkylene oxide addition products, such as tridecyl alcohol-C.sub.16 ethoxylate; soaps, such as sodium stearate; alkylnaphthalenesulfonate salts, 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 dialkyl phosphate esters.

Other adjuvants commonly utilized in agricultural formulations include crystallization inhibitors, viscosity modifiers, suspending agents, spray droplet modifiers, pigments, antioxidants, foaming agents, light-blocking agents, compatibilizing agents, antifoam agents, sequestering agents, neutralizing agents and buffers, corrosion inhibitors, dyes, odorants, spreading agents, penetration aids, micronutrients, emolients, lubricants, sticking agents, dispersing agents, thickening agents, freezing point depressants, antimicrobial agents, and the like. The formulations can also contain other compatible components, for example, other herbicides, herbicide safeners, plant growth regulants, fungicides, insecticides, and the like and can be formulated with liquid fertilizers or solid, particulate fertilizer carriers such as ammonium nitrate, urea and the like or mixed with sand, or dirt (in the case of solid - granular application).

The formulation of the present invention can be prepared in various solid forms such as granular formulation, jumbo formulation or the like. Conventional methodology, well known to the skilled person, can be used to prepare the formulation of the present invention. For example, a granular formulation may be prepared in the following manner.

The HPPD inhibitor(s), water soluble aluminium salt (s), silicate mineral(s) and other ingredients are mixed uniformly. Amounts of the ingredients to be mixed are selected such that their contents in the formulation become as those described hereinbefore. If necessary, HPPD inhibitor(s) and other agrochemical(s) are beforehand ground in order for them to be uniformly mixed with other ingredients. Then, water or another suitable solvent is added to the thus obtained uniform mixture, which is then kneaded using a kneader and subsequently subject to extrusion granulation by means of an extruder. The granules thus formed are dried and subject to particle size adjustment, whereby the formulation of the present invention is prepared. However, the formulation can be prepared by any conventional method e.g extruder granulation, compression formation, granulation by fluidized bed, pan granulation or the like. The present invention still further provides a method of controlling undesirable vegetation at a locus which comprises applying to the locus a controlling amount a herbicidal formulation according to the present invention. Preferably, the method relates to selectively controlling weeds in rice, in particular weeds in transplanted and direct- seeded rice. In a preferred embodiment of the method, the herbicidal formulation is applied directly into the paddy field water.

The skilled person will appreciate that solid herbicidal formulations can be applied to the locus using a variety of means - for example by hand or by machine direct.

The method can be used to control weeds in indica-type or japonica-type rice varieties.

The method is particularly suited to the control of undesired weeds emerging in paddy fields such as Amaranthaceae, Caryophyllaceae, Chenopodiaceae, Commelinaceae, Compositae, Convolvulaceae, Cruciferae, Cyperaceae, Equisetaceae, Euphorbiaceae, Gramineae, Labiatae, Leguminosae, Malvaceae, Oxlidaceae, Portulaacaceae, Polygonaceae, Rubiaceae, Scrophulariaceae, Solanaceae, Violaceae and Umbelliferae.

The solid herbicidal formulation of the present invention may be applied to the paddy field water either before or shortly after seeding. In a preferred embodiment, the herbicidal formulation is applied before seeding or after seeding but pre-emergence of the rice crop.

The solid herbicidal formulation of the present invention may be applied to the paddy field water before or after transplanting of rice.

The rate at which the HPPD inhibitor is applied will depend on a number of factors, for example the weeds to be controlled, the climatic conditions etc. In general an application rate of between 0.5g ai/ha and 500g ai/ha is appropriate, for example between 50g and 250g ai/ha. The specific rate to be applied will be readily determinable by the skilled person.

The present invention will now be illustrated further with reference to the following examples. EXAMPLES Example 1

66 parts by weight of clay (NK300, a product of Showa Chemical Co.. Ltd., filler), 25 parts by weight of Na-bentonite (Kunigel V-I, a product of Kunimine Kogyo Co., Ltd., a silicate mineral), 2 parts by weight of dextrin (Dextrin ND-S, a product of Nichiden Kagaku Co., Ltd., a binder material), 3 parts by weight of an anionic surfactant (SORPOL 5060, a product of Toho Chemical Co., Ltd.) and 1.33 parts by weight, of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG. an HPPD inhibitor) are when mixed using a mixer to obtain uniform powder, to which 10 parts by weight of a ca. 30% aqueous aluminium sulfate solution (a product of Toshin Kagaku Co., Ltd.) are added, followed by mixing to obtain a uniform mixture. Then, water is added and the mixture is further subject to mixing. The amount of water added is 15% by weight based on the total weight of the mixture including the water added. The thus prepared mixture is then subject to granulation by means of a basket extruder, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1 % by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione.

Into a 500ml bottle made of glass containing 200ml of 3 degree German hardness water, the above formulation is added in an amount of 240mg, which corresponds to a concentration of 12ppm mesotrione when all the mesotrione contained therein is released. The bottle is then left standing in a room kept at a temperature of 25°C, and 5ml of the water are taken away from the bottle using a Pipetteman P-5000, followed by HPLC analyses. 1,2,4 and 7 days, as well as 2 and 4 weeks thereafter. The HPLC analyses are performed under the following conditions:

Column: a tube made of stain- Jess steel having a diameter of 4.6mm and a length of 250mm

Filling material: Nucleosil CIB (5um in particle size)

Column temperature: 45 ^OC

Mobile phase: a 0.2% aqueous phosphoric acid solution/acetonitrile = 50/50 Flow rate: 1.0 ml/min Detection wavelength: 254nm

Injection volume: lOuI

The results from the release tests are as follows:

Time elapsed (days) Mesotrione released (%)

1 26.7

2 45.3

4 68.6

7 83.8

14 91.1

28 92.8

Example 2

Mesotrione released (%)

63 parts by weight of clay (NK300, a product of Showa Chemical (Co., Ltd., filler), 25 parts by weight of Na-bentonite (Kunigel V-I, a product of Kunimine Kogyo Co., Ltd., a silicate mineral), 2 parts by weight of dextrin (Dextrin ND-S, a product of Nichiden Kagaku Co., Ltd., a binder material), 3 parts by weight of an anionic surfactant (SORPOL 5060, a product of Toho Chemical Co., Ltd,) and 1.33 parts by weight of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG, an HPPD inhibitor) are well mixed using a mixer to obtain uniform powder, to which 20 parts by weight of a ca. 30% aqueous aluminium sulphate solution (a product of Toshin Kagaku Co., Ltd,) are added, followed by mixing to obtain a uniform mixture. Then, water is added and the mixture is further subject to mixing. The amount of water added is 10% by weight based on the total weight of the mixture including the water added. The thus prepared mixture is then subject to granulation by means of a twin screw extruder, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1 % by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione in the same manner as in Example 1. The results from the release tests are as follows: Time elapsed (clays ^' ) Mesotrione released (%)

1 34.6

2 42.6

4 58.2

7 69.1

14 74.1

28 76.6

Example 3

61 parts by weight of clay (NK300, a product of Showa Chemical Co., Ltd., filler), 25 parts by weight, of Na-bentonite (Kunigel V-I, a product of Kunimine Kogyo Co., Ltd., a silicate mineral), 2 parts by weight of dextrin (Dextrin ND-S, a product, of Nichiden Kagaku Co., Ltd., a binder material), 3 parts by weight of an anionic surfactant (SORPOL 5060, a product of Toho Chemical Co., Ltd.), 2 parts by weight of citric acid (purity ca. 99%, a product of Merck) and 1.33 parts by weight of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG, an HPPD inhibitor) are well mixed using a mixer to obtain uniform powder, to which 20 parts by weight of a ca. 30% aqueous basic aluminum chloride solution (a product of Toshin Kagaku Co., Ltd.) arc added, followed by mixing to obtain a uniform mixture. Then, water is added and the mixture is further subject to mixing. The amount of water added is 15% by weight based on the total weight of the mixture including the water added.

The thus prepared mixture is then subject to granulation by means of a pan granulator, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1 % by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione in the same manner as in Example 1. The results from the release tests are as follows: Time elapsed (days) Mesotrione released (%)

1 9.4

2 9.8

4 18.8

7 31.4

14 48.1

28 54.8

Example 4

65.5 parts by weight of clay (NK300, a product of Showa Chemical Co., Ltd., filler), 25 parts by weight of montmolironite (Kunipia F, a product of Kunimine Kogyo Co., Ltd., a silicate mineral, 5 parts by weight of starch (Amicol C, a product of Nippon Starch Chemical Co., Ltd., a binder material, 0.5 parts by weight of an anionic surfactant (Newkalgen EP70G, a product of Takemoto Oil & Fat Co., Ltd.) and 1.33 parts by weight of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG, an HPPD inhibitor) are well mixed using a mixer to obtain uniform powder, to which 10 parts by weight of a ca. 30% aqueous polyaluminum chloride solution (a product of Toshin Kagaku Co., Ltd.) are added, followed by mixing to obtain a uniform mixture. Then, water is added and the mixture is further subject to mixing. The amount of water added is 10% by weight based on the total weight of the mixture including the water added. The thus prepared mixture is then subject to granulation by means of a disc pelleter, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1 % by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione in the same manner as in Example 1. The results from the release tests are as follows: Time elapsed Cdavs) Mesotrione released (%)

1 12.7

2 23.6

4 37.2

7 54.2

14 70.2

28 79.5

COMPARATIVE EXAMPLES

In order to confirm the effect and advantage of the present invention, release behaviour of an HPPD inhibitor in the absence of the combination, a cationic substance with a silicate mineral, will be illustrated by means of the following comparative examples:

Comparative Example 1

93.5 parts by weight of clay (NK300, a product of Showa Chemical Co., Ltd., filler), 2 parts by weight of dextrin (Dextrin ND-S, a product of Nichiden Kagaku Co., Ltd., a binder material), 0.5 parts by weight of an anionic surfactant. (Newkalgen EP70G, a product of Takemoto Oil & Fat Co., Ltd,) and 1.33 parts by weight of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG, an HPPD inhibitor) are well mixed using a mixer to obtain uniform powder, to which 10 parts by weight of a ca. 30% aqueous aluminium sulfate solution (a product of Toshin Kagaku Co., Ltd.) are added, followed by mixing to obtain a uniform mixture. Then, water is added and the mixture is further subject to mixing. The amount of water added is 15% by weight based on the total weight of the mixture including the water added.

The thus prepared mixture is then subject to granulation by means of a basket extruder, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1 % by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione in the same manner as in Example 1. The results from the release tests are as follows: Time elapsed (days) Mesotπone released (%)

1 89.8

2 96.3

4 99.7

7 100.0

14 100.0

28 100.0

Comparative Example 2

71.5 parts by weight of clay (NK300, a product of Show a Chemical Co., Ltd., filler), 25 parts by weight of Na-bentonite (Kunigel V-I, a product of Kunimine Kogyo Co., Ltd., a silicate mineral), 2 parts by weight of dextrin (Dextrin ND-S, a product of Nichiden Kagaku Co., Ltd., a binder material), 0.5 parts by weight of an anionic surfactant (Newkalgen EP7OG, a product of Takemoto Oil & Fat Co., Ltd,) and 1.33 parts by weight of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG, an HPPD inhibitor) are well mixed using a mixer to obtain uniform powder, to which 10 parts by weight of water are added, followed by mixing to obtain a uniform mixture. The thus prepared mixture is then subject to granulation by means of a basket extruder, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1 % by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione in the same manner as in Example 1. The results from the release tests are as follows:

Time elapsed (days) Mesotrione released (%)

1 95.1

2 97.7 4 98.8

7 99.0

14 100.0

28 100.0 Comparative Example 3

59 parts by weight of kaolin clay (NK300, a product of Showa Chemical Co., Ltd., filler), 25 parts by weight of Na-bentonite (Kunigel V-I, a product of Kunimine Kogyo Co., Ltd., a silicate mineral), 2 parts by weight of dextrin (Dextrin ND-S, a product of Nichiden Kagaku Co., Ltd., a binder material), 3 parts by weight of an anionic surfactant (SORPOL 5060, a product of Toho Chemical Co., Ltd.), 10 parts by weight of calcium chloride, 1.33 parts by weight of mesotrione (purity ca. 75%, a product of Syngenta Crop Protection AG, an HPPD inhibitor) and 23 parts by weight of water are well mixed using a mixer to obtain a uniform mixture. The thus prepared mixture is then subject to granulation by means of a basket extruder, followed by drying and sieving, whereby a granular formulation containing mesotrione in an amount of 1% by weight, based on the total weight of the formulation, is obtained.

Subsequently, the above prepared formulation is subject to release tests to measure the release behaviour of mesotrione in the same manner as in Example 1. The results from the release tests are as follows:

Time elapsed (days) Mesotrione released (%)

1 85

2 100

These results show that the formulations of the present invention exhibit much preferred controlled release of the active ingredient from the formulation.

EXAMPLES WITH OTHER ACTIVE INGREDIENTS.

Additional tests were performed to understand the utility of other Active Ingredients with the controlled formulation of the present invention. Tests procedures were similar to those already described. The tables indicate the % active ingredient released from the formulation comprising (i) 20% polyaluminium chloride (PAC), (ii) 20% aluminium sulphate (AS) or (ii) no water soluble aluminium salt at a given time (days) following application. As can be seen - the release of the active ingredient is delayed when the formulation of the present invention is used.

Potassium-Glyphosate

Bensulfuron-methyl

Pyroquilon

Trinexapac-ethyl.