Agrochemical compositions and methods employing the dihydrate of the calcium salt of 3-hydroxy-5- methylisoxazole

Abstract: A combination of 3-hydroxy-5-methylisoxazole has with an antimicrobial agent has good agricultural fungicidal activity which lasts longer than 3-hydroxy-5-methylisoxazole alone. The dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole has advantages over the free 3-hydroxy-5-methylisoxazole, other salts and the anhydrous compound.

Description: The present invention relates to a specific hydrate of the calcium salt of 3-hydroxy-5-methylisoxazole and to certain new compositions and methods employing said compound. 3-Hydroxy-5-methylisoxazole, which is also known by the common name "hymexazol" and is sold by Sankyo Co. Ltd. under the trade name "Tachigaren", is disclosed, inter alia , in British Patent Specification No. 1 113 618. Subsequent British Patent Specifications No. 1 199 737 and 1 256 835 disclose other methods of preparing it and disclose its alkali metal salts. Japanese Patent Applications No. Sho 45-38953, Sho 45-72625, Sho 39-73350, Sho 45-29263 and Sho 45-108798 disclose various specific uses for this compound for the treatment or prevention of various plant diseases or as a plant growth regulator; these applications also disclose the calcium salt of 3-hydroxy-5-methylisoxazole as being especially useful, although no disclosure is made of any hydrate of the compounds. A complete review of the uses and activities of 3-hydroxy-5-methylisoxazole appears in Ann. Sankyo Res. Lab., 25 , 1 - 51 (1973). Soil-borne diseases affecting various kinds of crops and caused by soil-inhabiting pathogens have resulted in major problems for a long time in crop culture and agricultural administration, because they cause considerable damage and because they are difficult to control adequately. These problems have been made worse by the tendency, in recent years, to adopt schemes of intensive or mono- culture which result in a single type of crop being cultivated for many years continuously on the same soil, either in greenhouses or in open fields. As a consequence, occurrences of soil-borne diseases have greatly increased, and these have resulted in much damage and financial loss, since they can lead to a reduced or non-existent harvest. Typical soil inhabiting pathogens causing such soil-borne diseases include microorganisms belonging to the genera Fusarium , Pythium , Aphanomyces and Rhizoctonia . 3-Hydroxy-5-methylisoxazole is at present widely used to prevent a wide range of soil-borne diseases caused by such soil inhabiting pathogens because it is both effective and highly safe. For example, it is used, inter alia , for the prevention of seedling damping-off of rice and other crops caused by Pythium and Fusarium spp ., Fusarium wilts of various crops caused by Fusarium sp . and sugar beat damping-off caused by Aphanomyces sp . 3-Hydroxy-5-methylisoxazole can prevent these soil-borne diseases not only by direct application to the soil, but also by treatment of seeds of potentially affected plants. For example, seed treatment with 3-hydroxy-5-methylisoxazole will very effectively control seedling damping off of sugar beet caused by Aphanomyces and Pythium sp. . Accordingly, a seed dressing of 3-hydroxy-5-methyl- isoxazole is widely used in Japan and in many European countries. In addition 3-hydroxy-5-methylisoxazole is known to have some physiological effects on various crop plants. For example, it will promote the growth of roots and will enhance the physiological activities of roots. Accordingly, it is very common in Japan to treat rice seeds with 3-hydroxy-5-methylisoxazole prior to sowing them in flooded paddy fields; and it is known that this treatment is effective to stabilise the establishment of rice seedlings. Furthermore, when 3-hydroxy-5-methylisoxazole and/or salts thereof are used in hydroponics, they show an algicidal effect against, for example, pond scum. The calcium salt of 3-hydroxy-5-methylisoxazole is known, as mentioned in Japanese Patent Application Kokai No. Sho 48-38148, to have similar activities to 3-hydroxy-5-methylisoxazole itself against plant diseases affecting various kinds of crops. In addition, since the calcium salt of 3-hydroxy-5-methylisoxazole has a lower volatility than 3-hydroxy-5-methylisoxazole, the salt has practical advantages when used for seed treatment. In soil, however, 3-hydroxy-5-methylisoxazole is rapidly decomposed by soil microorganisms. This is a factor which limits its residual effectiveness, as reported in Ann. Sankyo Res. Lab. 25 , 42 - 45. If the dose of 3-hydroxy-5-methylisoxazole is greatly increased in order to prolong the residual effectiveness, phytotoxicity, such as growth inhibition or delayed germination, may occur on the treated plant, especially with seed treatment. The calcium salt of 3-hydroxy-5-methylisoxazole is, in this respect also, better than 3-hydroxy-5-methylisoxazole, because the phytotoxicity caused by the calcium salt with seed treatment is lower than that caused by 3-hydroxy-5-methylisoxazole. However, if used in a large amount, even the calcium salt sometimes causes phytotoxicity. It is, therefore, difficult to prolong the residual effectiveness by much increasing the amount of 3-hydroxy-5-methylisoxazole or of its calcium salt. Despite the usefulness of 3-hydroxy-5-methylisoxazole and derivatives thereof, there is, therefore, a need to improve the residual effectiveness of these compounds. Hitherto, it has been considered an advantage of 3-hydroxy-5-methylisoxazole and derivatives thereof that these compounds are readily decomposed in the soil, ultimately to carbon dioxide, thus leaving few residues and reducing take-up by the plants, which could lead to incorporation of the compounds in the food chain. Such incorporation is always thought to be best avoided even though these compounds are notably non-toxic to animals, including humans. Synergistic mixtures of 3-hydroxy-5-methylisoxazole and salts thereof with various antimicrobial agents have been disclosed in FR 2088407, JP 56087506, JP 56079605 and JP 49001728. We have now discovered that the hitherto unknown dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole has particular advantages over the 3-hydroxy-5-methylisoxazole itself and its known salts, as explained in detail hereafter. Accordingly, in one aspect, the present invention provides, as a new composition of matter, the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. The present invention also provides an agrochemical composition comprising the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. In another aspect, the present invention provides a soil fungicidal composition comprising the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole in admixture with or in association with an antimicrobial agent. The dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole may be represented by the formula (II): The dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole can be prepared by reacting a calcium compound with 3-hydroxy-5-methylisoxazole, and then recovering the desired calcium salt of 3-hydroxy-5-methylisoxazole under conditions favouring the formation of the dihydrate. For example, it may be obtained by the following procedure: one part (molar) of calcium hydroxide and 2 parts (molar) of 3-hydroxy-5-methylisoxazole are added to water and dissolved at a relatively high temperature, preferably from 70 to 90°C, more preferably approximately 80°C; the resulting solution is then filtered whilst still warm, after which the filtrate is cooled to a suitable temperature to promote the formation of crystals of the dihydrate, suitably approximately 0°C; the depositing crystals are then removed by filtration and dried, for example at 50 - 60°C. It should, however, be noted that these conditions are given only by way of example and that the reaction and separation conditions may be varied widely. The process of the present invention embraces all conditions which will produce the desired dihydrate. In one aspect of the present invention, the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole is employed in admixture with or in association with an antimicrobial agent. The nature of the antimicrobial agent will, of course, affect the longevity of the composition of the present invention. However, it may be selected from a wide range of such compounds using criteria well recognised in the art. We prefer to use an antibacterial or antifungal compound which is known to be very safe for industrial use, or a bactericidal or fungicidal compound known for agricultural use. Examples of suitable antimicrobial agents include: aldehydes and compounds capable of releasing aldehydes during use (i.e. when applied to the soil, water, plants, plant material or other material to be treated), alcohols including halogen-substituted nitro-alcohol derivatives and alcohols having an aryl substituent, quaternary ammonium salts, lipophilic weak acids (including benzoic acid, substituted benzoic acids, esters of these acids and phenols), thiazole derivatives (including isothiazolones), epoxides, substituted benzene and pyridine derivatives (especially the halogenated derivatives), compounds capable of releasing carbon disulphide during use including the tetrahydro- thiadiazine thiones, guanidines and biguanides, antimicrobial halogen-substituted amides, organic and inorganic copper compounds, arsenic compounds including arsines, and various other antimicrobial agents including other fungicides and anthelmintics. Specific examples of such compounds include: aldehydes: especially dialdehydes, such as glyoxal, succinic dialdehyde and 1,5-pentanedial; aldehyde releasing compounds: that is compounds which release an aldehyde, especially formaldehyde, during use, for example, 2,5-dimethoxytetrahydrofuran, 5-halo-5-nitrodioxanes (such as 5-bromo-5-nitrodioxane), 2-halo- N -hydroxymethylacetamides (such as 2-chloro- N -hydroxymethylacetamide), 1-hydroxymethyl-5,5-dimethylhydantoin, hexamethylenetetramine, 1-(3-haloallyl)-3,5,7-triaza-1-azoniaadamantane halides [such as 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride], 1,3-bis(hydroxymethyl)-5,5-dimethyl-2,4-imidazolidinedione, 4,4-dimethyl-1,3-oxazolidine and hexahydro-1,3,5-tris(2-hydroxyethyl)- S -triazine; halogen-substituted nitro-alcohol derivatives: for example compounds of formula R a -C(NO 2 )X-CH(OH)-R b in which X represents a halogen atom, preferably a chlorine or bromine atom, R a and R b are the same or different and each represents an alkyl group having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, a hydroxy group, a hydrogen atom or a halogen atom, such as 2-bromo-2-nitro-1,1-propanediol; quaternary ammonium salts: especially compounds of formula R c -N + Me 2 -CH 2 -Ph X - in which X represents a halogen atom, preferably a chlorine atom, Ph represents a phenyl group, and R c represents an alkyl group having from 1 to 20, preferably from 8 to 18, and more preferably from 12 to 14, carbon atoms, and more preferably a benzalkonium halide in which R c represents a mixture of alkyl groups having from 12 to 14 carbon atoms; alcohols having an aryl substituent: especially alcohols having from 1 to 6, more preferably from 1 to 4 carbon atoms, which are substituted by at least one aryloxy or benzyloxy group, such as benzyloxymethanol; lipophilic weak acids: for example, benzoic acid and substituted benzoic acids (preferably hydroxy-substituted benzoic acids) and esters of these acids; examples of esters include the alkyl esters having from 1 to 10 carbon atoms, such as the methyl, ethyl, propyl, butyl, heptyl, octyl and 2-ethylhexyl esters, and aralkyl esters in which an alkyl group having from 1 to 4 carbon atoms is substituted by at least one (and preferably from 1 to 3) aryl groups, preferably phenyl groups, such as benzyl esters; and phenols, especially those in which phenol is substituted by at least one further aryl, preferably phenyl, group, such as o -phenylphenol; isothiazolones: for example, isothiazol-3(2 H )-one, 1,2-benzisothiazol-3(2 H )-one, 5-halo-2-methylisothiazol-3(2 H )-ones [such as 5-chloro-2-methylisothiazol-3(2 H )-one], and 2-alkylisothiazol-3(2 H )-ones in which the alkyl group has from 1 to 10 carbon atoms [such as 2-methylisothiazol-3(2 H )-one]; benzene and pyridine derivatives containing halogen atoms: for example 2,4,5,6-tetrahaloisophthalonitriles (such as 2,4,5,6-tetrachloroisophthalonitrile), haloxylenols, especially p -halo- m -xylenols (such as p -chloro- m -xylenol) and halocresols, especially p -halo- o -cresols and p -halo- m -cresols (such as p -chloro- o -cresol and p -chloro- m -cresol); carbon disulfide releasing compounds: that is compounds which release carbon disulphide during use, such as tetrahydro-3,5-dimethyl-2 H -1,3,5-thiadiazine-2-thione, bis(dimethylthiocarbamoyl) disulphide and salts, especially alkali metal salts, of N -methyldithiocarbamic acid, such as sodium N -methyldithiocarbamate; guanidines and biguanides: for example alkylguanidines, in which the alkyl part has from 1 to 20, preferably from 10 to 20, carbon atoms, such as dodecylguanidine, and bis[5-(halophenyl)-biguanido]hexane dihydrohalides {such as bis[5-( p -chlorophenyl)biguanido]hexane dihydrochloride}; halogen-substituted amides: especially fatty acid amides, for example haloacetamides (such as chloroacetamide or bromoacetamide) and 2,2-dihalo-3-nitrilopropionamides (such as 2,2-dibromo-3-nitrilopropionamide); copper compounds: such as cupric hydroxide, copper sulphate and copper-8-quinolate; arsine compounds: such as 10,10'-oxybis-10 H -phenoxarsine; other antimicrobial agents, including other fungicides and anthelmintics: such as 2-(4-thiazolyl)-1 H -benzimidazole, N -(dichlorofluoromethylthio)phthalimide and N , N -dimethyl- N '-(dichlorofluoromethylthio)sulphamide. Of these, we prefer: 1,5-pentanedial (hereinafter referred to as Compound B-1), 2,5-dimethoxytetrahydrofuran (hereinafter referred to as Compound B-2), glyoxal (hereinafter referred to as Compound B-3), benzalkonium chloride (hereinafter referred to as Compound B-4), 1,2-benzisothiazolin-3-one (hereinafter referred to as Compound B-5), cupric hydroxide (hereinafter referred to as Compound B-6), 4-chloro-2-xylenol (hereinafter referred to as Compound B-7), 4-chloro-2-cresole (hereinafter referred to as Compound B-8), p -hydroxybenzoic acid esters, for example the alkyl esters in which the alkyl part has from 1 to 6 carbon atoms (for example the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, neopentyl, 2-methylbutyl, 1-ethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 2-ethylbutyl, hexyl and isohexyl groups, of which we prefer those alkyl groups having from 1 to 4 carbon atoms, preferably the methyl, ethyl, propyl and butyl groups, and most preferably the propyl group), benzyl esters and aryl esters, particularly the phenyl ester; p -hydroxybenzoic acid is hereinafter referred to as Compound B-9, and tetrahydro-3,5-dimethyl-2 H -1,3,5-thiadiazine-2-thione (hereinafter referred to as Compound B-10). The most preferred antimicrobial agents are Compound B-1 and Compound B-5. It is possible, in accordance with the present invention, to use a single one of these antimicrobial agents or to use a combination of two or more of them. There is no particular restriction on the relative amounts of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole and the antimicrobial agent, and the relative amounts can range from, for example, 99 : 1 to 1 : 99 by weight. However, we prefer that the weight ratio of the amount of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole to the antimicrobial agent should be from 15 : 1 to 1 : 2, more preferably from 13 : 1 to 1 : 1 by weight. It will, of course, be appreciated that the two main active compounds in the composition of the present invention can, and preferably are, supplied to the end user in admixture. However, this is not essential and the benefits of the invention will also be achieved if these two components are supplied separately and applied together. Accordingly, the present invention also embraces the concurrent or essentially concurrent use of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole and the antimicrobial agent for the treatment of soil, plants water or parts, especially the reproductive matter, of plants, as well as the concurrent or effectively concurrent supply of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole and the antimicrobial agent for the treatment of soil, plants water or parts, especially the reproductive matter, of plants. Reflecting the activity of the compositions of the present invention, the invention further provides formulations which contain the compositions of the invention, together with a carrier and optionally other auxiliary agents, if necessary. These compositions may be formulated as preparations of the type commonly employed for agricultural or horticultural use, for instance as dusts, coarse dusts, microgranules, fine microgranules, wettable powders, and various liquid formulations, such as emulsifiable concentrates and aqueous or oily suspensions. The carrier employed in such compositions may be natural or synthetic and organic or inorganic; it is generally employed to assist the active ingredient to reach the substrate to be treated, and to make it easier to store, transport or handle the active compound. It may be solid or liquid. Suitable solid carriers include: inorganic substances, such as clays (examples of which are bentonite, kaolinite, montmorillonite and attapulgite), talc, mica, agalmatolite, pyrophyllite, pumice, vermiculite, gypsum, calcium carbonate, dolomite, diatomaceous earth, magnesium carbonate, apatite, zeolite, silicic anhydride and synthetic calcium silicate; vegetable organic substances, such as nut shells (e.g. of walnuts or other nuts), soybean meal, tobacco powder, walnut powder, wheat flour, wood meal, starch and crystalline cellulose; synthetic or natural high molecular weight polymers, especially resins, such as cumarone resins, petroleum resins, alkyd resins, polyvinyl chloride, polyalkylene glycols, ketone resins, ester gums, xanthan gum, copal gum and dammar gum; waxes such as carnauba wax and beeswax; or urea. Examples of suitable liquid carriers include: paraffinic or naphthenic hydrocarbons, such as kerosene, mineral oil, spindle oil and white oil; aromatic hydrocarbons, such as benzene, toluene, xylene, solvent naphtha, ethylbenzene, cumene and methylnaphthalene; halogenated hydrocarbons, especially chlorinated hydrocarbons, such as carbon tetrachloride, chloroform, trichloroethylene, monochlorobenzene and o -chlorotoluene; ethers such as dioxane and tetrahydrofuran; ketones, such as acetone, methyl ethyl ketone, diisobutyl ketone, cyclohexanone, acetophenone and isophorone; esters such as ethyl acetate, amyl acetate, ethylene glycol acetate, diethylene glycol acetate, dibutyl maleate and diethyl succinate; alcohols such as methanol, ethanol, isopropanol, hexanol, ethylene glycol, diethylene glycol, cyclohexanol, and benzyl alcohol; ether alcohols, such as ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether; other polar solvents, such as dimethylformamide and dimethyl sulphoxide; and water. The compositions of the invention may contain one or more surface active agents and/or polymers to improve the properties of the compositions and help them to disperse, emulsify, spread, penetrate and bind or to control disintegration, improve fluidity or impart corrosion resistance to the composition, or to stabilize the active compound. Any of the conventional classes of surface active agent (non-ionic, anionic, cationic or amphoteric) may be employed, but it is preferred to employ non-ionic and/or anionic surface active agents whereby wetting, adhesion and absorption and desired effects may be improved. Examples of suitable non-ionic surface active agents include: polyoxyethylene alkyl ethers, oxyethylene/oxypropylene block polymers, the polymerisation adducts of ethylene oxide with higher alcohols, such as lauryl alcohol, stearyl alcohol and oleyl alcohol; the polymerisation adducts of ethylene oxide with alkylphenols, such as isooctylphenol or nonylphenol; the polymerisation adducts of ethylene oxide with alkylnaphthols, such as butylnaphthol or octylnaphthol; the polymerisation adducts of ethylene oxide with higher fatty acids, such as palmitic acid, stearic acid or oleic acid; the polymerisation adducts of ethylene oxide with mono- or di- alkylphosphoric acids, such as stearylphosphoric acid or dilauryl- phosphoric acid; the polymerisation adducts of ethylene oxide with amines, such as dodecylamine; amides or ethoxylated amides of higher fatty acids, such as stearylamide; higher fatty acid esters of polyhydric alcohols, such as sorbitan, and the polymerisation adducts of ethylene oxide therewith; higher fatty acid esters of glycerol borates or of ethoxylated glycerol borates; and glycerides and sucrose esters of fatty acids. Examples of suitable anionic surface active agents include: aryl sulphonate salts, especially alkylbenzenesulphonates and alkylnaphthalenesulphonate, such as sodium isopropylnaphthalenesulphonate, sodium methylenebisnaphthalenesulphonate, and sodium dodecylbenzenesulphonate; phosphates or sulphates of polyoxyethylenealkyl ethers; β-naphthalenesulphonate-formalin condensate salts; ligninsulphonates, such as sodium ligninsulphonate; polymer surfactants of the polycarboxylate and/or polysulphonate type; condensed phosphates, such as sodium hexametaphosphate or sodium tripolyphosphate; salts of higher fatty acids, i.e. soaps, e.g. sodium oleate; salts, e.g. sodium and calcium salts, of sulphonic acids and the acids themselves, e.g. ligninsulphonic acid, and or alkyl sulphonate salts, especially sodium dialkyl sulphosuccinates, such as sodium dioctyl sulphosuccinate or sodium 2-ethylhexenesulphonate and equivalent salts with metals other than sodium; salts, e.g. sodium, ammonium and amine salts, of polyoxyethylene alkyl aryl ether sulphates or of polyoxyethylene alkyl ether sulphates or the free acids; or salts of polyoxyethylene alkyl aryl ether phosphates or of polyoxyethylene alkyl phosphates; and alkyl sulphate salts, such as sodium lauryl sulphate or oleyl sulphate amine salt. Examples of suitable cationic surfactants include: the higher aliphatic amines and ethylene oxide condensates with such amines; quaternary ammonium salts, e.g. chlorides; N -alkylamine acetates; and N -alkylamine oxides; Examples of amphoteric surfactants include betaines and amino acid-type surfactants. Moreover, the compositions of the present invention may be used in combination with high molecular weight compounds or other formulation agents, for example: protective colloids, such as casein, gelatin, gum arabic, albumin, glue, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose or polyvinyl alcohol; dispersing agents, such as sodium polyphosphate; inorganic dispersing agents, such as bentonite or veegum; stabilizers; binding agents; and anti-freezing agents. For wider applicability and labor saving, the composition of the invention can, if desired, be combined with one or more other agrochemicals, e.g. fungicides, insecticides, herbicides, plant growth regulators and fertilizers. The above-mentioned carriers and various auxiliary agents may be used alone or in any desired combination, depending upon the type of preparation, the application and other factors. Similar factors will also be of importance in determining the concentration of the active compound in the formulation. In general terms, we prefer that the compositions of the present invention should contain one part by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methyl-isoxazole and from 0.01 to 10 parts by weight, more preferably from 0.1 to 1 parts by weight, of the antimicrobial agent(s). The total content of the active ingredients may vary over a wide range and is not critical to the present invention. In general, it will vary depending upon the nature of the formulation. For example: A liquid formulation, such as an emulsifiable concentrate, may conveniently contain, for example, from 1 to 50%, more preferably from 5 to 50%, by weight of the active compounds and from 5 to 20% by weight of an emulsifying agent, the remainder being a liquid carrier, together with, if required, a corrosion inhibitor. Oil preparations may conveniently contain from 0.5 to 5% by weight of the active compounds, the remainder being a liquid carrier such as kerosene. Dusts may conveniently contain from 0.1 to 25%, more preferably from 0.3 to 25%, by weight of the active compounds, the remainder being a solid carrier. Wettable powders may conveniently contain, for example, from 1 to 90%, preferably from 25 to 80%, by weight of the active compounds, the remainder being a solid carrier and a dispersing and wetting agent, if required, together with a protective colloidal agent, a thixotropic agent and an anti-foaming agent. Granules may conveniently contain from 0.3 to 35%, more preferably from 0.3 to 25%, by weight of the active compound, a major portion of the remainder being a solid carrier. The active compound is homogeneously admixed with the solid carrier or is adhered to or adsorbed onto the carrier surface; the diameter of each granule is preferably from 0.2 to 1.5 mm. The soil fungicidal composition of the present invention may be prepared for use by combining the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole with one or more of the aforementioned antimicrobial agents by conventional means; for example, by simple mixing, if desired with other conventional ingredients, as described above, to give conventional agrochemical formulations. These formulations may be mixed with one or more other active components, such as other fungicides, bactericides, insecticides, acaricides, fertilizers and soil conditioners, as well as, if desired, carriers and/or diluents or formulation aids. These formulations may be applied to seeds or soil directly or after dilution to a suitable concentration depending on the purpose. If used for hydroponic culture, direct addition to the nutrient solution may be possible. The timing of the application is not particulary critical, and the formulations can be applied at seeding or at transplanting time. No injury will be caused to crops, even if the formulations are applied during crop growing stages. Many agrochemicals, including 3-hydroxy-5-methylisoxazole, can cause rusting or corrosion of the apparatus used to prepare or apply or store or dispense them. Furthermore, 3-hydroxy-5-methylisoxazole itself is relatively volatile and so will gradually volatilise on storage, which is not viewed favourably by the purchaser. Moreover, 3-hydroxy-5-methylisoxazole and its anhydrous salts readily burn, thus leading to the possibility of a fire hazard. We have now surprisingly discovered that the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole is free from these disadvantages, and, in particular, does not cause or promote rusting or corrosion, even when the active compound is employed in the form of a wettable powder or as water-dispersible granules. 3-Hydroxy-5-methylisoxazole has hitherto been employed as dust formulations, dust coating formulations and liquid formulations. However, since 3-hydroxy-5-methylisoxazole has an acidic hydroxy group in its molecule, it exhibits such disadvantages as causing rust and/or corrosion of the apparatus used for preparing these formulations. Water-dispersible granules have many advantages, such as: 1) they do not give rise to dust when handled; 2) they are not bulky, since the apparent specific gravity is as small as 1/2 to 1/3 that of wettable powders; and 3) easy preparation of homogenous dispersions is possible by the addition of water. In general, this type of formulation is prepared by adding water to a mixture of the active compound, a filler, a dispersing agent and a binder, forming the mixture into granules, and then drying them and passing them through a sieve. However, since the vapor pressure of 3-hydroxy-5-methylisoxazole is relatively high, i.e. 0.133 Pa at 25°C, there are problems arising from evaporation of the active ingredient in the drying step of this preparation time. Hitherto, it has not been advantageous to use 3-hydroxy-5-methylisoxazole in such water-dispersible granules because it causes rusting and/or corrosion of apparatus, particularly that used to prepare the formulations. However, we have now surprisingly found that the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole can overcome these problems. Thus, in accordance with a further aspect of the present invention there is provided a fungicidal and bacteriocidal composition for agricultural and horticultural use characterised in that it comprises the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. In a burning test, anhydrous forms of 3-hydroxy-5-methylisoxazole, its sodium salt, its potassium salt and its calcium salt all kindle and burn easily to make a fire when briefly contacted with a slightly live coal. On the other hand, the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole is almost impossible to set fire to and burns only reluctantly. Furthermore, the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole has considerable physicochemical stability and is not hygroscopic at a relative humidity of 80% at 40°C. Moreover, it will not lose its water of crystallisation below 40°C, even at a relative humidity of 5%. When the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole is used, no rusting or corrosion of the apparatus is observed during the preparation of agrochemical formulations containing it, and the active ingredient does not evaporate during the drying step involved in the preparation of water dispersible granular formulations. In contrast, the sodium and potassium salts of 3-hydroxy-5-methylisoxazole cannot be used economically because of their strongly hygroscopic nature. The dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole can be prepared by reacting a calcium compound with 3-hydroxy-5-methylisoxazole, and then recovering the desired calcium salt of 3-hydroxy-5-methylisoxazole under conditions favouring the formation of the dihydrate. For example, it may be obtained by the following procedure: one part (molar) of calcium hydroxide and 2 parts (molar) of 3-hydroxy-5-methylisoxazole are added to water and dissolved at a relatively high temperature, preferably from 70 to 90°C, more preferably approximately 80°C; the resulting solution is then filtered whilst still warm, after which the filtrate is cooled to a suitable temperature to promote the formation of crystals of the dihydrate, suitably approximately 0°C; the depositing crystals are then removed by filtration and dried, for example at 50 - 60°C. It should, however, be noted that these conditions are given only by way of example and that the reaction and separation conditions may be varied widely. The process of the present invention embraces all conditions which will produce the desired dihydrate. The resulting dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole is a whitish crystalline substance, and can be formulated into any conventional agrochemical preparation known for 3-hydroxy-5-methylisoxazole itself, for example, it can be formulated as dusts, dust coatings, wettable granules and liquid formulations according to conventional means. If desired, other agrochemicals (for example, fungicides such as metalaxyl, oxadixyl, triadimefon, prochloraz, benomyl and thiophanate-methyl, and insecticides such as furathiocarb, benfuracarb and carbosulphan) can be incorporated in the formulation, as described generally above. Examples of methods which may be used to prepare the formulations of the present invention are as follows. The same methods may also be used to prepare similar formulations in accordance with the first aspect of the present invention. A dust formulation can be obtained by mixing the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole with a fine powder of a mineral substance, for example, clay, talc or calcium carbonate, preferably less than 45 µm in diameter, after which the mixture is pulverised, preferably using a pulverizer of the swing-hammer type. A dust coating formulation can be obtained by mixing the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole with any other conventional additives, optionally after adding a filler. Examples of fillers which may be employed for the preparation of a dust coating formulation, include: fine dusts of a mineral substance less than 45 µm in diameter, such as clay, talc, calcium carbonate, white carbon or titanium dioxide; a starch derivative, such as starch or an esterified starch; or a sugar, such as dextrin, glucose, fructose or saccharose. Additives which may be used for the preparation of dust coating formulations include surfactants, such as the non-ionic surfactant and anionic surfactants exemplified above; binders and thermoplastic resin powders. Examples of binders which may be employed for maintaining and binding the active ingredients onto the surfaces of seeds, include water-soluble high molecular weight compounds, for example, water-soluble polysaccharides, such as alginic acid and salts thereof, carboxymethylcellulose and salts thereof, methylcellulose, polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone or xanthan gum. Examples of thermoplastic resin powders having a membrane-forming capacity which may be employed include ethylene - vinyl chloride copolymer resin powder, ethylene - vinyl acetate copolymer resin powder and vinyl chloride resin powder. The dust coating formulation may be prepared by combining the active ingredient with one or more of these additives, depending on the purpose of the formulation. In general, the ranges which may be employed are from 10 to 95%, from 0 to 90%, from 0 to 20% and from 0 to 70% for the active ingredient, filler, wet dispersing agent, binder and thermoplastic resin powder respectively. A water-dispersible granular formulation can be prepared by mixing the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole with one or more additives selected from fillers, wet dispersing agents and binders, as described above in relation to the dust coating formulation, and then pulverizing the mixture. The pulverised mixture is then preferably added to an agitating fluidised bed granulator, water is added, and the whole is mixed and granulated, after which it is dried and sieved. The water-dispersible granules usually have a particle diameter from 63 to 1700 µm. For preparation of the liquid formulation, selection of the solvent is most important. The solvent must have the following properties: it must be capable of dissolving the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole; it must not affect the stability of the active ingredient; it must mix well with water; it must have a low phytotoxicity; and it must have a relatively high boiling point. Examples of solvents which satisfy these conditions include ethylene glycol, propylene glycol and dipropylene glycol. The liquid formulation can be prepared by dissolving the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole in one or more of the solvents mentioned above or in a mixture of one or more of these solvents with water. During the preparation of the liquid formulation, an antimicrobial agent, such as a lower alkyl (methyl, ethyl, propyl or butyl) ester of para-hydroxybenzoic acid, or 1,2-benzisothiazolin-3-one (B.I.T.) may be added. The invention is further illustrated by the following non-limiting Examples, in which all parts and percentages are by weight. The antimicrobial agents used are identified by the codes assigned to them above. EXAMPLE 1 5.2 parts of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (prepared as described in Example 1A), 4 parts of Protectol GDA (a Trade name for an antimicrobial agent containing 50% of Compound B-1, a product of BASF Japan Co., Ltd.), 4 parts of Carplex #80 (a Trade name for a hydrated amorphous silicon dioxide; a product of Shionogi & Co., Ltd.) and 86.8 parts of Zeeklite NG (a Trade name for a fine dust containing kaolinite and cesosite as the main ingredients; a product of Zeeklite Co., Ltd.) were mixed and pulverised by a hammer mill to prepare a dust formulation of the present invention. EXAMPLE 2 Sixty five parts of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (prepared as described in Example 1A), 10 parts of Protectol GDA, 2 parts of Gohsenol GL-05S (a Trade name for polyvinyl alcohol; a product of Nippon Synthetic Chemical Industry Co., Ltd.)and 23 parts of Carplex #80-S were mixed and pulverised by a hammer mill to obtain a wettable powder formulation of the present invention. EXAMPLE 3 Sixty five parts of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (prepared as described in Example 1A), 25 parts of Proxel GXL (a Trade name for an antimicrobial agent containing 20% of Compound B-5; a product of ICI Japan Co., Ltd.), 2 parts of Gohsenol GL-05S and 8 parts of Carplex #80-S were mixed and pulverised by a hammer mill to obtain a wettable powder fromulation of the present invention. COMPARATIVE EXAMPLE 1 Using 4 parts of Protectol GDA, 4 parts of Carplex #80 and 92 parts of Zeeklite NG, a dust formulation was obtained by following a procedure similar to that described in Example 1. COMPARATIVE EXAMPLE 2 Using 5.2 parts of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (prepared as described in Example 1A) and 94.8 parts of Zeeklite NG, a dust formulation was obtained by following a similar procedure to that described in Example 2. COMPARATIVE EXAMPLE 3 Using 65 parts of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (prepared as described in Example 1A), 2 parts of Gohsenol GL-05S and 33 parts of Carplex #80-S, a wettable powder formulation was obtained by following a similar procedure to that described in Example 3. COMPARATIVE EXAMPLE 4 Using 10 parts of Protectol GDA, 2 parts of Gohsenol GL05S and 88 parts of Carplex #80-S, a wettable powder formulation was obtained by following a similar procedure to that described in Example 2. COMPARATIVE EXAMPLE 5 Using 25 parts of Proxel GXL, 2 parts of Gohsenol GL-05S and 73 parts of Carplex #80-S, a wettable powder formulation was obtained by following a similar procedure to that described in Example 3. ACTIVITY DATA The composition of the present invention can greatly enhance and prolong the disease controlling effect and physiological activities of 3-hydroxy-5-methylisoxazole and salts thereof, and can improve the residual effect. These properties permit the compositions of the present invention to be used in amounts corresponding to lower doses of 3-hydroxy-5-methylisoxazole or salt thereof than was hitherto possible. EXPERIMENT 1 Control of Rice seedling damping-off (Dust formulation) A culture of Pythium graminicola (previously cultivated with shaking in a potato-sucrose medium) was homogenised using a blender to obtain a suspension of its hyphae. This suspension was mixed with sterilised soil. The soil sample inoculated with the pathogen was packed in a small plastic nursery box, 20 x 20 cm, 3 cm deep. The infested soil was treated with the dust formulation of Example 1 and the dust formulation of Comparative Examples 1 and 2. Rice seeds (var.: Koshihikari ), which had been previously immersed for germination, were then immediately sown at the rate of 30 g of dry rough rice seeds per box. The seedlings were grown in a glass-house kept at 20°C in the daytime and 15°C in the night. The diseased area resulting from the rice seedling damping-off was measured 2 or 3, and 5 weeks after sowing. The inhibition of growth of the rice seedlings was examined 2 weeks after sowing by comparison with a control free from the pathogen. As is shown in Table 1, the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole exhibited poor residual effectiveness when applied alone. Also all of the antibacterial ingredients used in this test had a weak controlling effect when applied alone. However, when the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole was combined with any of the antibacterial ingredients, the controlling effect of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole was greatly increased including its residual effectiveness. In addition, no phytotoxicity, such as rice seedling growth inhibition, was observed after application of any of the other compositions. On the contrary, growth of the roots was promoted and healthy seedlings were obtained. The results are shown in Table 1. In the following Table, the inhibition of rice seedling growth is reported using the following symbols: -: No growth inhibition is observed. ±: Slight growth inhibition is observed. +: Seedling height is no more than 2/3 of normal ++: Seedling height is no more than 1/3 of normal +++: No germination Compound D is the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. Test compound Area affected by rice seedling damping-off (%) Rice seedling growth inhibition Dosage 2 weeks after sowing 5 weeks after sowing (Compound D) (Compound B-1) Example No.1 10 5 0 0 - 20 10 0 0 - (Compound B-1) Comp. Example No.1 5 40 100 - 10 30 80 - (Compound D) Comp. Example No.2 10 18 80 - 20 5 65 - Untreated control 50 100 - EXPERIMENT 2 Control of Sugar beet seedling damping-off (Wettable powder) A suspension of the pathogen (which had previously been cultured with shaking in a potato-sucrose medium was mixed with sterilised soil. The soil sample was packed into a plastic pot (size 2 litres). Sugar beet seeds (var.: Monomidori and Hokkai No. 51) were coated with the wettable powder formulations obtained as described in Examples 2 and 3 and Comparative Examples 3, 4 and 5 together with 2% gum arabic liquid. The coated sugar beet seeds were sown at the rate of 60 seeds per pot. After culture in a greenhouse for 6 weeks, the number of healthy seedlings was determined. The results were averaged over 3 identically treated pots in each case. As is shown in Table 2, the soil fungicidal composition of the present invention exhibited a remarkable activity against damping-off of sugar beet seedlings, and, moreover, no phytotoxicity was observed. Test compound Monomidori Hokkai 51 Dosage % of healthy seedlings Phytotoxicity % of healthy seedlings Phytotoxicity (Cpd. D) (Cpd. B-1) Ex. 2 1.0 0.1 90 - 93 - 1.5 0.15 93 - 95 - (Cpd. D) (Cpd. B-5) Ex. 3 1.0 0.1 85 - 90 - 1.5 0.15 95 - 95 - (Compound D) Comp. Ex. 3 1.0 50 - 75 - 1.5 55 - 80 - (Compound B-1) Comp. 0.1 8 - 10 - Ex. 4 0.15 10 - 14 - (Compound B-5) Comp. Ex. 5 0.1 7 - 11 - 0.15 10 - 13 - Untreated control 5 - 8 - EXAMPLE 1A 5.7 kg of water, 0.57 kg of calcium hydroxide and 1.4 kg of 3-hydroxy-5-methylisoxazole were added to a 10 liter glass flask, and the mixture was heated to 80°C until the solids had dissolved. It was then filtered whilst still warm. The filtrate was then cooled to 0°C. The crystals which separated were collected by filtration and dried for 2 hours at 55°C to obtain 1.0 kg of crude white crystals. These were recrystallised from water and then dried for 2 hours at 55°C to afford white crystals, melting at 280°C (with decomposition). Elemental analysis: Calculated for C 8 H 8 N 2 O 4 Ca.4H 2 O: C, 31.17%; H, 5.23%; N, 9.09%. Found: C, 31.09%; H, 5.24%; N: 9.07%. Infrared Absorption Spectrum (KBr), ν max cm -1 : 3377(s), 3220(w), 1650(w), 1626(s), 1510(s), 1410(s), 1255(s), 1150(s), 1025(s), 900(s) Nuclear Magnetic Resonance spectrum (D 2 O), δ ppm: 2.11 (3H, doublet, J = 0.8 Hz); 5.36 (1H, quartet, J = 0.8 Hz). Water content by Karl-Fischer method Calculated (%): 23.37 Found (%) : 23.62. From these analytical data, the compound obtained was confirmed to be the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. EXAMPLE 2A 6.5 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (the crude white crystals obtained as described in Example 1A; 97.8% purity, calculated as the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole) and 93.5 parts by weight of Zeeklite NG (a Trade name for a fine dust containing kaolinite and sericite as the main ingredients; a product of Zeeklite Co., Ltd.) were mixed and then finely powdered, using a hammermill-type pulverizer (Ecksample mill Type KII-1; Product of Fuji Powdal Co., Ltd.), to obtain a dust formulation. EXAMPLE 3A 64.5 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (purity 97.8%) and 35.5 parts by weight of Carplex #80 (a Trade name for a hydrated amorphous silicon dioxide; a product of Shionogi & Co., Ltd.) were mixed and then finely powdered, using an Ecksample mill Type KII-1, to obtain a dust coating formulation. EXAMPLE 4A 80.0 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (purity 98.8%), 19.0 parts by weight of Carplex #80 and 1.0 parts by weight of Gohsenol GL-05S (a Trade name for a polyvinyl alcohol; a product of Nippon Synthetic Chemical Industry Co., Ltd.) were mixed and then finely powdered, using an Ecksample mill Type KII-1, to obtain a dust coating formulation. EXAMPLE 5A 90.0 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (purity 98.8%), 7 parts by weight of FARZYM-T (a Trade Name for a denatured starch; a product of Matsutani Chem. Ind. Co., Ltd.) and 3 parts by weight of Neogen Powder (a Trade Name for sodium alkyl[C 12 ]benzenesulphonate; a product of Dai-Ichi Kogyo Seiyaku Co., Ltd.) were mixed and then finely powdered, using an Ecksample mill Type KII-1, to obtain a dust coating formulation. EXAMPLE 6A 50.0 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (purity 98.8%), 45.0 parts by weight of Caoline KCS (a Trade Name for a fine powder of kaolinite clay; a product of Matsumura Ind. Co., Ltd.) and 5.0 parts by weight of Labelin FAN (a Trade Name for a sodium salt of a condensation product of naphthalenesulphonic acid and formalin; a product of Dai-Ichi Kogyo Seiyaku Co., Ltd.) were mixed, and the mixture was pulverised, using an Ecksample mill Type KII-1, to obtain 1000 g of a pulverised product. This product was charged into a Vertical Granulator Type FM-VG-05 (an agitating granulator; a product of Powrex Co. Ltd.), 150 g of water were added, mixed with stirring for 3 minutes at a blade speed of 800 rpm and at a cross screw speed of 3000 rpm. The granular product obtained was dried using a fluidised bed dryer, Mizet Dryer Type MD-B-400 (a product of Fuji Powdal Co., Ltd.) until at an inlet air temperature of 60°C, an outlet air temperature of 50°C was achieved. The product was sieved to select particles of diameter from 105 µm to 840 µm, and thus to obtain the desired water-dispersible granular formulation. EXAMPLE 7A 26 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (purity 97.8%) were added to a mixture of 53 parts by weight of ethylene glycol and 21 parts by weight of water and dissolved, to obtain a liquid formulation. COMPARATIVE EXAMPLE 1A A procedure similar to that described in Example 6A was repeated, except that 50.0 parts by weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole (purity 98.8%) were replaced by 32.0 parts by weight of 3-hydroxy-5-methylisoxazole (purity 98.7%) and that 45.0 parts by weight of Caoline KCS were replaced by 63.0 parts by weight of Caoline KCS, a water-dispersible granular formulation was obtained. EXPERIMENT 1A Evaporation of active compound in the drying process The theoretical content of active compounds in the products of Example 6A and Comparative Example 1A were compared to the actual content of active compound by measuring the actual content of active compound both before and after the drying process using a fluidised bed dryer and described in Example 6A. The theoretical and actual contents of the active compounds were calculated without regard to the water content because the water content was less than 1.0%. In the products of Example 6A and Comparative Example 1A, when the water content of the samples was 1.5% or more, caking (where particles adhered to each other) was observed during storage of the water-dispersible granular formulation. To maintain a satisfactory quality, it is necessary to have a water content less than 1.0%. The water content of the samples was measured as follows. About 5 g of each sample was allowed to stand for 48 hours in a desiccator containing phosphorus pentoxide at ambient temperature, and the difference between the weight before and after standing in the desiccator was assumed to be the water content. On standing for 48 hour in a desiccator, hardly any evaporation of the active compound occurred because phosphorus pentoxide only absorbs water and does not absorb 3-hydroxy-5-methylisoxazole. Accordingly, the content of active compound after standing in a desiccator is almost the same as that before. The content of the active compound, the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole in the composition of Example 6A or 3-hydroxy-5-methylisoxazole itself in the composition of Comparative Example 1A, was measured as follows. 3-Hydroxy-5-methylisoxazole About 0.7 g of the sample was extracted with 50 ml of methanol. 5 ml of this solution were charged into a 50 ml Erlenmeyer flask, 5 ml of a methanolic solution containing 10 mg of phthalic acid, 1.0 ml of 0.1 N aqueous sulphuric acid and 19 ml of water (for use as an internal standard) were then added to the flask. 5 µl of this solution was injected into a high performance liquid chromatography (HPLC) column. The eluted active compound and phthalic acid were detected and quantified with an ultraviolet monitor (240 nm) and a digital integrator. A calibration curve prepared from standard solutions was used in order to determine the amount of the active compound in the sample. HPLC conditions: column : 4.6 x 250 mm Zorbax ODS (Trade Mark) Mobil phase : methanol, water and 1% phosphoric acid, in a ratio of 30 : 68 : 2 by volume; Flow rate : 1 ml/minute. Dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole As the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole is changed to 3-hydroxy-5-methylisoxazole in an acidic solution, the analytical method for this compound is the same as that for 3-hydroxy-5-methylisoxazole. The percentage content (D%) of the dihydrate of the calcium salt is calculated as follows; D% = A x B / C where A : content of 3-hydroxy-5-methylisoxazole (wt%); B : molecular weight of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole; C : molecular weight of 3-hydroxy-5-methylisoxazole. The "remaining rate" means the content of active compound after the drying process expressed as a percentage of the content of active compound before the drying process. The theoretical content of active compound after the drying process was 49.4% and 31.6% in Example 6A and Comparative Example 1A, respectively. The results are shown in the following Table 3. Example 6A Comp. Example 1A Water content (%) 0.9 0.9 Active cpd. content (%) 49.4 26.3 Remaining rate 100.0 83.2 In Example 6A, no evaporation of the active compound was observed during the drying process, but in Comparative Example 1A, 16.8% of the active compound was lost during the drying process. EXPERIMENT 2A 5 g samples of the anhydrous potassium, sodium and calcium salts of 3-hydroxy-5-methylisoxazole and the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole were placed on a porcelain dish (10 cm diameter). The compounds were set fire to with a match and their combustibilities were compared. The results were as follows: 1) Potassium salt of 3-hydroxy-5-methylisoxazole (water content: 1.5%): This compound burned explosively with white smoke, and had totally evaporated almost immediately. 2) Sodium salt of 3-hydroxy-5-methylisoxazole (water content: 1.0%): This compound burned explosively with white smoke, and had totally evaporated almost immediately. 3) Calcium salt of 3-hydroxy-5-methylisoxazole (anhydrous): This compound burned vigorously with black smoke. 4) Calcium salt of 3-hydroxy-5-methylisoxazole (dihydrate): Although it sometimes gave off sooty smoke, this compound did not burn. Repeated attempts to set fire to it, even as many as 5 times, caused no burning, although it ultimately resulted in evaporation of the compound. EXPERIMENT 3A 5 g samples of the anhydrous potassium and sodium salts of 3-hydroxy-5-methylisoxazole and the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole were placed on a glass dish and allowed to stand in a desiccator kept at a relative humidity of 80% at 40°C. The water content of the anhydrous potassium and sodium salts increased rapidly, and had increased by about 90% after 48 hours. The rate of increase then began to reduce, but the total increase in water content after 96 hours was over 100% (sodium salt) or almost 100% (potassium salt). On the contrary, the water content of the calcium salt dihydrate showed essentially no increase over the whole period of the test (96 hours). From these results, it is clear that the anhydrous potassium and sodium salts of 3-hydroxy-5-methylisoxazole were hygroscopic, however, no hygroscopicity was found in the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. It is also clear that neither the potassium salt nor the sodium salt of 3-hydroxy-5-methylisoxazole forms a stable hydrate.

Claims: The dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. A process for the preparation of the compound of Claim 1, in which one part (molar) of calcium hydroxide and 2 parts (molar) of 3-hydroxy-5-methylisoxazole are added to water, and dissolved at 70 - 90°C, the resulting solution is filtered, whilst still warm, the filtrate is cooled to approximately 0°C and the crystals of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole are removed by filtration and dried. An agrochemical composition comprising the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. A soil fungicidal composition comprising the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole in admixture with or in association with an antimicrobial agent. The composition of Claim 4 wherein the ratio of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole to the antimicrobial agent is from 15 : 1 to 1 : 2. The composition of Claim 5, wherein the ratio of the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole to the antimicrobial agent is from 13 : 1 to 1 : 1. The composition of any one of Claims 4 to 6, wherein the antimicrobial agent is selected from 1,5-pentanedial, 2,5-dimethoxytetrahydrofuran, glyoxal, benzalkonium chloride, 1,2-benzisothiazolin-3-one, cupric hydroxide, 4-chloro-2-xylenol, 4-chloro-2-cresole, p -hydroxybenzoic acid esters and tetrahydro-3,5-dimethyl-2 H -1,3,5-thiadiazine-2-thione. The composition of Claim 7, wherein the antimicrobial agent is selected from 1,5-pentanedial and 1,2-benzisothiazolin-3-one. A method of protecting crops, other plants, soil or other agricultural media from fungal attack by applying to plants, parts of plants, soil or water the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole. A method of protecting crops, other plants, soil of other agriculutral media from fungal attack by applying to plants, parts of plants, soil or water the dihydrate of the calcium salt of 3-hydroxy-5-methylisoxazole in admixture with or in association with an antimicrobial agent.

Inventors: FUJIMOTO MASAHIKO, HOSODA HITOSHI, KATO SHIGEHIRO, KOBAYASHI KOZO, KONDO YASUHIKO, OHKOUCHI TAKEO, SABI HIROSHI, TAKAHI YUKIYOSHI, TANIZAWA KINJI, YASUI KENJI, FUJIMOTO, MASAHIKO, HOSODA, HITOSHI, KATO, SHIGEHIRO, KOBAYASHI, KOZO, KONDO, YASUHIKO, OHKOUCHI, TAKEO, SABI, HIROSHI, TAKAHI, YUKIYOSHI, TANIZAWA, KINJI, YASUI, KENJI, Fujimoto, Masahiko, c/o Sankyo Company Limited, Hosoda, Hitoshi, c/o Sankyo Company Limited, KATO, SHIGEHIRO, C/O SANKYO COMPANY LIMITED, Kobayashi, Kozo, c/o Sankyo Company Limited, KONDO, YASUHIKO, C/O SANKYO COMPANY LIMITED, OHKOUCHI, TAKEO, C/O SANKYO COMPANY LIMITED, Sabi, Hiroshi, c/o Sankyo Company Limited, TAKAHI, YUKIYOSHI, C/O SANKYO COMPANY LIMITED, Tanizawa, Kinji, c/o Sankyo Company Limited, Yasui, Kenji, c/o Sankyo Company Limited
Applicants: SANKYO CO, SANKYO COMPANY LIMITED
Application year: 1993
Main classification: A01N43
IPC codes: A01N43, A01N37, A01N59, C07D261, A01N33, A01P3, A01N31, A01N35