GB2122492A - Biologically active compositions containing diazolopyrazine derivatives - Google Patents

Abstract

Biologically active compositions containing a compound of the general formula I, or a metal salt complex or salt thereof: <IMAGE> wherein R<1> represents an optionally substituted alkyl group, an optionally substituted ring having 5 or 6 atoms in the ring at least one of which is nitrogen, oxygen or sulphur, or an optionally substituted phenyl group; R<2> represents a hydrogen atom, a hydroxy group, a halogen atom, an optionally alkyl substituted amino or hydrazino group, an optionally substituted alkyl, alkoxy, or alkylthio group, or an optionally substituted ring having 5 or 6 atoms in the ring at least one of which is nitrogen, oxygen or sulphur; together with a carrier. The compositions exhibit a range of herbicidal, fungicidal and plant growth regulating activities.

Description

SPECIFICATION Biologically active compositions containing diazolopyrazine derivatives The present invention relates two biologically active compositions containing diazolopyrazine derivatives, and to novel diazolopyrazine derivatives.

Certain diazolopyrazine derivatives are disclosed in the literature. There is no suggestion however that these compounds have any use in agriculture, except in U.S. Patent Specification No. 3,850,929, which discloses that certain diazolopyrazines have antimicrobial activity. The specification also states that certain of those compounds have herbicidal properties; the herbicidal activity however is very low for these specific derivatives.

TheApplicants have nowfound that compositions containing certain diazolopyrazine derivatives have useful biological activity. The present invention provides a biologically active composition comprising a compound of the general formula I, or a metal salt complex orsaltthereof

wherein R1 represents an optionally substituted alkyl group or an optionally substituted ring having 5 or 6 atoms in the ring at least one ofwhich is nitrogen, oxygen or sulphur, or an optionally substituted phenyl group;R2 represents a hydrogen atom, a halogen atom, a hydroxy group, an optionally alkyl substituted amino orhydrazino group, an optionally substituted alkyl, alkoxy or alkylthio group oran optionally substituted ring having 5 or 6 atoms in the ring at least one of which is nitrogen, oxygen or sulphur; and X represents an oxygen, sulphur, selenium or tellurium atom; together with a carrier.

Throughoutthis specification, unless otherwise stated, any alkyl, alkoxy or aikylthio group present preferably contains up to 6, especially up to 4, carbon atoms.

Suitable substituents which may be present in an optionally substituted aliphatic group include halogen atoms, alkoxy, alkylthio, cyano, carboxy, alkoxycarbonyl, hydroxy, amino and cycloalkyl groups and optionally substituted phenyl or phenoxy groups. Suitable substituents which may be present in an optionally substituted phenyl group include halogen atoms, hydroxy, methylenedioxy, amino, cyano, alkylsulphonyl, and nitro groups and optionally substituted alkyl, alkenyl, alkynyl, alkoxy, alkylthio, alkoxycarbonyl, phenyl and phenoxy groups.

A phenyl group R' is preferably unsubstituted or substituted by up to 3 ofthe same or different substituents given above. Most preferably it is u nsubstituted, monosubstituted or disubstituted.

Preferred substituents are selected from halogen atoms and nitro, cyano, alkyl, haloalkyl, alkoxy, haloalkoxy and alkylthio groups.

As noted above R1 and/or R2 may represent an optionally substituted ring having 5 or6 atoms inthe ring at least one of which is nitrogen, oxygen or sulphur. Suitable heterocyclic groups in this regard include optionally substituted pyridyl, pyrrolyl, pyrazolyl, imidazolyl, pyrazinyl, pyridazinyl, pyrimidinyl, furyl and thienyl groups, and also the corresponding partially or fully saturated analogues.

A heterocyclic group may be substituted by one or more ofthe substituents given above for a phenyl group; preferably however it is unsubstituted or substituted by one or more alkyl groups or halogen atoms; most preferably such a group is unsubsti- tuted.

A heterocyclic group is preferably bonded through a carbon atom to the diazolopyrazine nucleus of a compound of general formula 1. A nitrogen atom of a heterocyclic group may be substituted by an oxygen atom to give the N-oxide derivative.

Preferably R1 represents an optionally substituted alkyl group of unto 6carbon atoms oran unsubstituted pyridyl orfuryl group or an optionallysubstituted phenyl group; preferably R2 represents a hydrogen atom, a hydroxy group, an optionally alkyl-substituted amino or hydrazino group, an optionally substituted alkyl group of to 6 carbon atoms, oran unsubstituted pyridyl orfuryl group.

More preferably R' is an unsubstituted alkyl group of up to 4 carbon atoms, especially a methyl or ethyl group or an unsubstituted pyridyl, furyl or phenyl group; more preferably R2 is a hydrogen atom oran unsubstituted alkyl group of up to 4carbon atoms, especially a methyl or ethyl group, or an unsubstituted pyridyl orfuryl group.

Xis preferably a sulphur or oxygen atom, especially a sulphur atom.

As stated above, the invention includescomposi- tions containing metal salt complexes and salts of compounds ofthe general formula I. Suitable salts include salts with sulphonic acids, for example benzene- or toluene-sulphonic acid, carboxylic acids, for exampletartaric or acetic acids, or inorganic acids, for example sulphuric acid orthe hydrohalic acids.

Suitable metal salts which form complexes with compounds ofthe general formula I includethose of heavy metals such as iron, copper, zinc and manganese, in which the anions may for example be derived from one ofthose acids given above.

Most of the compounds of the general formula I are believed to be novel. Therefore the invention also provides a novel compound ofthe general formula I or a metal salt complex or salt thereof wherein R7, R2 and X are as defined above provided that when R1 and R2are both methyl groupsxis not sulphur and when R1 is an optionallysubsituted phenyl group and R2 is a hydrogen atom, or when R' is an unsubstituted phenyl group and R2 is a methyl group, Xis not oxygen.

The invention further provides a process for the preparation of a novel compound according to the invention which comprises reacting a compound of the general formula Certain of the /The Chemical/mathematical formula(e) appearing in the printed specification was/were submitted after the date of filing, the formula(e) origingally submitted being incapable of being satisfactorily reproduced.

with a dicarbonyl derivative ofthe general formula

in which R1, R2 and X have the meanings given for the novel compounds of the general formula I; and if desired converting the resulting compound accord ingtotheinvention into any other compound according to the invention.

The molar ratio of the reactants is not critical and mayforexample be in the range offrom 5:1 to 1:5, especially 2:1 to 1:2.

The reaction is suitably carried out in the presence of a solvent, for example an acid, such as acetic acid, an alcohol, such as methanol or ethanol, a hydrocarbon of chlorinated hydrocarbon, such as methylene chloride, or an ether or ester, such as ethyl acetate.

Mixtures of solvents may be suitable.

The reaction is preferably carried out at a temperature in the range offrom 0 to 1 80"C, preferablyfrom 60 to 130"C. It may in some cases be convenientto carry out the reaction atthe refluxtemperature ofthe solvent used.

Compounds oftheformulae II and Ill may be prepared by methods analogous to methods known in the art.

A resulting free base of formula I may be converted into an acid addition salt or metal salt complex thereof by methods analogous to known methods, for example by reaction with the appropriate acid or salt. A resulting acid addition salt can be converted into the free base by reaction with an acid binding agentora base.

The compounds and compositions of the invention have been found to show interesting biological activity as herbicidesand/orfungicides and/or plant growth regulants. The invention therefore also provides a method of combating undesired plant growth and/or combating fungal attack and/or regulating plant growth at a locus, which comprises treating the locus with a compound or a composition according to the invention; the locus may, for example, be a crop area.

Application may be pre-emergence or, preferably, post-emergence. Application rates are preferably in the range offrom 0.1 to 4kg/ha active material.

A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated, which may for example be a plant, seed or soil, orto facilitate storage, transport or handling.Acarrier may be a solid ora liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any ofthe carriers normally used in formulating biologically active compositions may be used. Preferably compositions according to the invention contain 0.5 to 95% byweightofactive ingredient.

Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceousearths; magnesium silicates, for exampletalcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montomorillonites and micas; calcium carbonate; calcium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes, for example beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones,for exam ple acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for carbon tetrachloride, perchlororethylene and trichloroethane. Mixtures of different liquids are often suitable.

Agricultural compositions are often formulated and transported in a concentrated from which is subsequently diluted bythe user before application.

The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution. Thus preferably at least one carrier in a composition according to the invention is a surfaceactive agent. For example the composition may contain at leasttwo carriers, at least one ofwhich is a surface-active agent.

Asurface-active agent may be an emulsifying agent, a dispersing agent ora wetting agent; it may be nonionic or ionic. Examples of suitable surfaceactive agents include the sodium orcalcium salts of polyacrylic acids and lignin sulphonic acids; the condensation offatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the moleculewith ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaeryth ritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol oralkyl phenols, for example p-octyl phenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates ofthese condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric of sulphonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as sodium dodecylbenzenesulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions ofthe invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, sus pension concentrates and aerosols. Wettable powders usually contain 25,50 or 75% w of active ingredientand usuallycontain in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabiliser(s) and/or other additives such as penetrants or stickers.Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the fieid with further solid carrierto give a composition usually containing 1/2-10% wofactive ingredient. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676-0.152 mm), and maybe manufactured by agglomeration or impregnation techniques. Generally, granules will contain 1/2-25% w active ingredient and 0-10% w of additives such as stabilisers, slow release modifiers and binding agents.Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, co solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors. Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% wactive ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents,0-10% 0-10% of other additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation or as anti-freeze agentsfor water Aqueous dispersions and emulsions, for example compositions obtained bydiluting a wettable powder or a concentrate according to the invention with water, also lie within the scope ofthe present invention. The said emulsions may be ofthe water-inoil oroftheoil-in-watertype, and mayhaveathick 'mayon naise'-like consistency.

The composition of the invention may also contain other ingredients, for example, other compounds possessing herbicidal, plant growth regulating, insecticidal orfungicidal properties.

The following Examples illustrate the invention.

Example 1 Preparation of5,6- di(oc - pyridyl) (1,2,5Jthiadazolo(3,4 - b)pyrazine Thiadazolo(3,4-c)thiadazole (6.0was refluxed for 5 minutes in 3 molar aqueous ammonia solution (120cm3).Thewaterwas removed using rotary evaporation and the residue of diamine dissolved in glacial acetic acid (240cm3) and 2,2'-(o: - pyridyl) ethane dione (8.8g); the mixture was refluxed fo r 21/2 hours, cooled and water added.The product was extracted twice with chloroform.

The extractwas dried using sodium sulphate and the solvent evaporated off. The extract was purified by chromatography on neutral alumina using chloroform as an eluent.

The yield of 5,6 - di(oc - pyridyl) - (1,2,5)thiadazole (3,4 - b) - pyrazine was 6.8g (corresponding to 56.7% ), melting point212-216"C; the following elemental analysis results were obtained: Calculated: C: 57.5 H: 2.7 N: 28.8 Found: C: 57.3 H: 2.8 N: 28.6 Example 2 Preparation ofthe N-oxide ofthe compound of Example 1 5,6 - di(a - pyridyl) - (1 ,2,5)thiadiazolo(3,4,-b)pyr- azine (1.5g)was dissolved in methylene chloride (30cm3). Metachloroperbenzoic acid (1 .0g) was dissolved in methylene chloride (20cm3) and added to the first solution; the mixture was stirred for 22 hours at room temperature.

The product was washed with saturated sodium bicarbonate solution and methylenechloridesolu- tion and dried using sodium sulphate.

The solvent was evaporated off and the product purified by chromatography on neutral alumina using methylene chloride and methanol (98:2) as an eluent.

The yield of 5 - (oc - pyridyl) - 6 - (os - pyridyl - N - oxide) - (1,2,5) -thiadiazolo(3,4-b)pyrazine was 0.79 (corresponding to 76.7%); melting point230'C; the following elemental analysis results were obtained: Calculated: C: 54.5 H: 2.6 N: 27.3 Found: C: 54.4 H: 2.5 N: 27.2 Example 3 Preparation of5 - phenyl - (1,Z5)oxadizolo(3,4- b)pyrazine (a) Oxamide dioxime (35.49) was refluxed for 18 hours with sodium hydroxide (12.0g) in a minimum amount of water (1 Ocm3) and ethylene glycol (300cm3).The reaction mixture was cooled to room temperature and ethylene glycol was removed under high vacuum at 66"C/0.9mm Hg to leave a pale brown residue which was recrystallised from water to yield 16.29 of 3,4 diamino[1,2,5]oxadiazole, (corresponding to 54%); melting point 176"C; the following elemental analysis results were obtained: Calculated: C: 24.0 H: 4.0 N: 56.0 Found: C: 23.8 H: 4.0 N: 55.8 (b) 3,4diamino[1,2,5]oxadiazole (2.0g) was dissolved in glacial acetic acid (60cm3); phenylglyoxal (2.79) was dissolved in warm glacial acetic acid (60cm3) and added to the diamine solution and the mixture was refluxed with stirring for 21/2 hours.The acetic acid was removed by rotary evaporation, saturated sodium bicarbonate solution added to the orange residue and the product was extracted three times with chloroform. The extract was washed with bicarbonate solution, dried using sodium sulphate and the chloroform removed. The pale yellowfrac- tion was collected and recrystallised from methanol (130cm3) as yellow needles to yield 2.lug (corresponding to 53%) of 5 - phenyl - (1 ,2,5)oxadiazolo(3,4-b) pyrazine; melting point 139-142"C; the following elemental analysis results were obtained.

Calculated: C: 60.6 H: 3.0 N: 28.3 Found: C: 60.5 H: 2.9 N: 28.3 Examples 4 to 8 By methods analogous to those described in Examplesl to3,thefollowingcompoundsofthe general formula I were prepared. Analysis and physical data figures are given in Table I.

TABLE I

Example No. R R2 X Elemental Analysis Physical data C H N 4 II H S Calm: 56.1 2.8 26.2 Mpt: iis0c Found: 56.3 2.6 26.1 5 e 5 S Calm: 53.3 2.2 20.7 Mpt: 178-184 C Found: 53.4 2.1 20.8 6 Me Me S Calc: 43.4 3.6 33.7 Mpt: 118-120 e Found: 43.1 3.6 33.6 7 r 7cH3o S Calc: 54.1 3.3 22.9 Mpt: 11000 Found: 53.8 3.2 22.6 8 i}~ Cl S Calm: 48.3 2.0 22.5 Yellow oil Found: 47.6 2.2 22.0 Example 9 HerbicidalActivity To evaluate their herbicidal activity, compounds according to the invention were tested using as a representative range of plants: maize, Zea mays (MZ); rice, Oryzasativa (R); barnyard grass, Echinochloa crusgalli (BG); oat, Avena sativa (0); linseed, Linum usitatissimum (L); mustard, Sinapsis alba (M); sugar beet, Beta vulgaris (SB) and soya bean, Glycine max (S).

The test fall into two categories, pre-emergence and post-emergence. The pre-emergence tests involved spraying a liquid formulation of the compound onto the soil in which the seeds of the plant species mentioned above had recently been sown.

The post-emergence tests involved two types of test, viz., soil drench and foliar spray tests. In the soil drench teststhesoil in which the seedling plants of the above species were growing, was drenched with a liquid formulation containing a compound of the invention, and in thefoliarsprayteststhe seedling plants were sprayed with such a formulation.

The soil used in the tests was a prepared horticultu ral loam.

The formulations used in the tests were prepared by diluting with water, solutions ofthe test compounds in acetone containing 0.2% by weight of an alkylphenol/ethylene oxide condensate available underthetrade markTRITON X-1 55. The acetone solutions were diluted with water and the resulting formulations applied at dosage levels corresponding to 5 kg and 1 kg of active material per hectare in a volume equivalentto 650 litres per hectare in the soil spray and foliarspray tests, and at a dosage level equivalentto 10 kilograms of active material per hectare in a volume equivalentto approximately 3,000 litres per hectare in the soil drench tests.

In the pre-emergencetests untreated sown soil and in the post-emergence tests untreated soil bearing seedlings plants were used as controls.

The herbicidal effects of the test compounds were assessed visually twelve days after spraying the soil and the foliage and thirteen days after drenching the soil and were recorded on a linear 0-9 scale. A rating 0 indicates growth as untreated control, a rating 9 indicates death.

The results of the test are set out in Table II below. TABLE II

:ompound Soil Drench IDcsage I Foliar Spray Pre-emergence ,f lo kg/hs kg/ha Example No. Mz R BG O L M SB S Mz R BG O L M SB S Mz R BG O L M SB S 1 2 2 5 3 4 4 2 1 5 6 5 g 7 g g g 7 o o 4 o o 3 3 2 4 o 8 6 8 8 6 6 o o o o o 2 0 0 2 4 4 6 6 7 7 6 4 5 5 3 4 6 8 9 9 5 o o o o 2 3 2 2 1 3 2 4 5 7 8 9 3 0 O o O 0 0 0 0 3 0 O O 0 4 6 4 3 5 4 o 8 3 7 9 3 5 0 0 0 0 o o 0 0 1 2 0 8 2 7 8 14 0 0 o 0 o o 0 o 4 2 2 4 o 5 2 o 2 5 3 4 9 3 8 9 8 7 o o 5 3 4 o o o 1 3 2 8 0 7 8 6 6 o o 4 2 3 0 D O 5 6 2 7 4 7 8 5 4 5 3 0 5 3 3 5 0 2 0 0 0 0 0 0 0 0 1 o o 4 3 3 4 o o o o o o o o o o 6 4 2 5 3 4 5 4 5 5 - 2 2 6 3 5 7 5 7 2 0 4 3 4 5 6 3 i 1 1 o 5 2 3 5 2 6 2 0 1 3 0 3 4 1 1 l 0 5 2 3 5 2 6 2 0 1 3 0 3 4 1 7 4 0 3 0 0 4 0 0 5 0 0 0 3 6 4 2 3 o 6 2 3 6 B 2 1 o o o o 5 3 o o o 3 o o 4 3 o Example 10 The fungicidal activity of compounds ofthe invention is illustrated bythefollowing tests which were carried out.

(a) Activityagainst vine downy mildew (Plasmo- para viticola; P.v.a.) The test is a direct antisporulant one using a foliar spray. The lower surfaces of leaves of whole vine plants are inoculated by spraying with an aqueous suspension containing 105zoosporangia/ml 2 days priortotreatmentwiththetestcompound. The inoculated plants are kept for 24 hours in a high humidity compartment, and then 24 hours at glasshouse ambient temperature and humidity.The plants arethen dried and infected leaves detached and sprayed on the lower surfaces with a solution of active material in 1:1 water/acetone containing 0.04% Triton X-155. The spraying is carried outwith a moving tracksprayerwhich delivers 620 I/ha, and the concentration of active material is calculated to give an application rateof 1kg/ha.Afterdrying,the petioles ofthe sprayed leaves are dipped in water and the leaves returned to high humidity for a further96 hours incubation, followed by assessment. Assessment is based on the percentage ofthe leaf area covered bysporulation compared with thaton control leaves.

(b) Activity against vine greymould (Botrytis cinerea; B.c.) The test is a direct eradicant one using a foliar spray. The under-surface of the detached vine leaves are inoculated by pipetting ten large drops of an aqueous suspension containing 5 x 105 conidia/ml on tothem. The inoculated leaves kept uncovered overnight during which time the fungus has penetrated the leaf and a visible necrotic lesion may be apparentwherethe drop was made. The infected regions are sprayed directly with a dosage of 1 kg of active material perhectate using a track sprayer as described under (a). When the spray has dried the leaves are covered with petri dish lids and the disease allowed to develop under these humid conditions.

Theextentofthe necrotic lesion beyondtheoriginal drop together with the degree ofsporulation is compared with that on control leaves.

(c) Activity against barley powdery mildew (Ery siphe graminis; E.g.) The test measures the direct antisporulant activity of compounds applied as a foliarspray. For each compound about 40 barley seedlings were grown to the one-leaf stage in a plastic pot of sterile potting compost. Inoculation was effected by dusting the leaves with conidia of Erysiphe graminis, spp. hordei.

24 hours after inoculation the seedlings were sprayed with a solution ofthe compound in a mixture of acetone (50%), surfactant (0.04%) and water using a track sprayer as described under (a). The rate of application was equivalent to 1 kg of active material per hectare. First assessment of disease was made 5 days after treatment, when the overall level of sporulation on the treated plants was compared with that on control plants.

(d) Activity against apple powderymildew (Podosphaera leucotrica; P.l.) The test is a direct anti-sporulant one using a foliar spray. The upper surfaces of leaves of whole apple seedlings are inoculated by spraying with an aqueous suspension containing 105 conidia/ml 2 days priorto treatment with the test compound. The inoculated plants are immediately dried and kept at glasshouse ambienttemperatures and humidity prior to treatment. The plants are sprayed at a dosage of 1 kilogram of active material per hectare using a track sprayer. After drying the plants are returned to a compartment at ambienttemperature and humidity for up to 9 days, followed by assessment. Assessment is based on the percentage ofthe leafarea covered by sporulation compared with that on leaves of control plants.

(e) Activity against vine downy mildew (Plasmopara viticola; Pv.t) Thetest is a translaminar protectant one using a foliarspray.The upper surfaces of leaves of whole vine plants are sprayed at a dosage of 1 kilogram of active material per hectare using a track sprayer. The lowersurfaces ofthe leaves are then inoculated, upto 6 hours after treatment with the test compound, by spraying with an aqueous suspension containing 105 zoosporangia/ml. The inoculated plants are keptfor 24 hours in a high humidity compartment, 4 days at glasshouse ambienttemperature and humidity and then returned for a further 24 hours to high humidity.

Assessment is based on the percentage of leaf area covered bysporulation compared with that on control leaves.

(f) Activity against peanut leafspot (Cercospora arachidicola; Ca) The tests is a direct eradicantone using afoliar spray. The uppersurfaces ofthe leaves of peanut plants (12-20cms high, monopots) are inoculated by spraying with an aqueous suspension containing 105 conidia/ml 4043 hours prior to treatment with the test compound. The inoculated plants are kept at high humidity and then allowed to dry during the interval between inoculation and treatment by spraying at a dosage of 1 kg of active material per hectare using a track sprayer. After spraying the plants are moved to a humid compartment at 25-28 C for a further period of up to 10 days. Assessment is based on a comparison between the levels of disease on the treated and control plants.

(g) Activityagainstpotato late blight (Phytophtora infestans; P. i. p.) The test measures the direct protectant activity of compounds applied as a foliar spray. Tomato plants, CultivarAilsa Craig, 1-1 Scms high, in monopots are used. The whole plant is sprayed at a dosage of 1 kilogram of active material per hectare using a track sprayer. The plant is then inoculated upto 6 hours aftertreatmentwith the test compound, by spraying with an aqueous suspension containing 5 x 1 103 zoosporangia/ml. The inoculated plants are kept in high humidityfor3days.Assessmentis based on comparison between the levels of disease on the treated and control plants.

(h) Activity against wheat brown rust (Puccinia recondita P.rJ Thetest is a directantisporulantone using afoliar spray. Pots containing about 25 wheat seedlings per pot, atfirst leaf stage, were inoculated by spraying the leaves with an aqueous suspension, containing 105 spores/ml plus a little Triton X-1 55,20-24 hours before treatment with the compound under test. The inoculated plants were kept overnight in a high humidity compartment, dried at glasshouse ambient temperature and then sprayed art a dosage of 1 kilogram of active material per hectare using a track-sprayer. After treatment the plants were kept at glasshouse ambienttemperature and assessment made about 11 days after treatment.Assessment is based on the relative density of sporulating pustules per plant compared with that on control plants.

The extent of disease control achieved in these tests is expressed as a control rating in Table Ill below; greaterthan 80% disease control is given the rating 2 afterthetest; control of between 50 and 80% is given the rating 1 afterthetest.

TABLE III

Compound of Greater than 5DP disease control temple No. achieved in the belowindicated tests 1 P.v.a. (2); B.c. (1); E.g. (1).

2 P.r. (l).

3 P.v.t (1).

4 P.v.a. (2); E.g (1); P.1. (2).

8 P.v.a. (2); P.v.t. (1); B.c. (2); P.i.p. (1); C.a. (1). Example 11 Plant Growth RegulatingActivity To evaluate plant growth regulating activity wheat seeds were sown in 7cm monopots and grown at constanttemperature (185C) and light exposure (18 hours per day). When the plants had reached the 3 leaf stage, (a) one batch of 6 plants was sprayed with 0.3kg ha-1 ofthe compound undertest in 40% acetone and 0.4% TritonX-100.

(b) one batch of 6 plants was sprayed with 3kg ha1 of the compound under test in 40% active and 0.4% Triton X-100.

(c) The remainder were left as untreated controls. 40 days after sowing an assessment ofthe number of visible tillers (side shoots) per plant was made.

On each assessment, the number of tillers visible on the plants sprayed at 0.3kg ha-1 was found not be to significantly differentfrom the number on the untreated controls. The results below in Table IV showthe number of tillers visible on the plants sprayed at 3kg ha-1 expressed as a percentage ofthe control. The results show a marked reduction in the numberoftillers produced.

Compound of Example Do. Tillers visible on plants sprayed at 3kg ha l expressed as S of control 1 58% 2 25is

Claims (15)

1. A biologically active composition comprising a compound of the general formula I or a metal salt complex or saltthereof,

wherein R1 represents an optionally substituted alkyl group, an optionally substituted ring having 5or6 atoms in the ring at least one of which is nitrogen, oxygen or sulphur, or an optionally substituted phenyl group; R2 represents a hydrogen atom, a halogen atom, a hydroxy group, an optionally alkyl substituted amino or hydrazino group, an optionally substituted alkyl, alkoxy or alkylthio group, or an optionally substituted ring having 5 or 6 atoms in the ring at least one of which is nitrogen, oxygen or sulphur; and X represents an oxygen, sulphur, selenium ortellurium atom; together with a carrier.

2. A composition as claimed in claim 1, in which any aliphatic group R1 and/or R2 is unsubstituted or substituted by one or more ofthe same or different substituents selected from halogen atoms, alkoxy, alkylthio, cyano, carboxy, alkoxycarbonyl, hydroxy, amino and cycloalkyl groups and optionally substituted phenyl and phenoxy groups; and a phenyl or heterocyclic group R1 and/or R2 is unsubstituted or substituted by up to 3 of the same or different su bstituents selected from halogen atoms, hydroxy, amino, cyano, nitro, methylenedioxy and alkylsulphonyl groups and optionally substituted alkyl, alkenyl, alkynyl, alkoxy, alkylthio, alkoxycarbonyl, phenyl and phenoxygroups.

3. A composition as claimed in claim 1 or claim 2 in which R' represents an optionally substituted alkyl group of up to 6 carbon atoms or an unsubstituted pyridyl orfuryl group oran optionally substituted phenyl group.

4. A composition as claimed in claim 3 in which R1 represents an unsubstituted alkyl group of upto 4 carbon atoms or an unsubstituted pyridyl,furyl or phenyl group.

5. A composition as claimed in any one of the preceding claims in which R2 represents a hydrogen atom, a hydroxy group, an optionally alkyl substituted amino or hydrazino group, an optionally substituted alkyl group of to 6carbon atoms, a pyridyl N-oxide group, or an unsu bstituted pyridyl or furyl group.

6. A composition as claimed in claim 5 in which R2 represents a hydrogen atom or an unsubstituted alkyl group of up to 4 carbon atoms, a pyridyl N-oxide group, oran unsubstituted pyridyl orfuryl group.

7. A composition as claimed in any one of the preceding claims in which X represents an oxygen or sulphur atom.

8. A composition as claimed in any one of the preceding claims, in which the active ingredient is any one ofthose given in Examples 1 to 8 herein.

9. A composition as claimed in any one of claims 1 to 8, which comprises at least two carriers, at least one of which is a surface-active agent.

10. Acompound ofthe general formula I or a metal salt complex or acid addition salt thereof, wherein R7, R2 and X are as defined in Claim 1 providedthatwhen R1 and R1 are both methyl groups, Xis notsulphur, and when R1 is an optionally substituted phenyl group and R2 is hydrogen or when R1 is an unsubstituted phenyl group and R2 is a methyl group, Xis not oxygen.

11. Acompound as claimed in claim 10 and named in any one of Examples 1,2,4,5,7 and 8 herein.

12. A processforthe preparation ofa compound as claimed in claim 10 which comprises reacting a compound ofthe general formula

with a dicarbonyl derivative ofthe general formula

in which R1, R2 and X have the meanings given in claim 10; and if desired converting the resulting compound according to the invention into any other compound according to the invention.

13. A process as claimed in claim 12 substantially as described in Example 1 or Example 3 herein.

14. A compound as claimed in claim 10, whenever prepared by a process as claimed in either claim 12 or claim 13.

15. Amethodofcombating undesired plant growth and/or combating fungal attack and/or regulating plant growth art a locus which comprises treating the locus with a compound as claimed in any one of claims 10,11 and 14,ora composition as claimed in any one of claims 1 to 9.