METHYL ESTERS OF ALDIMINO- OR KETIMINO-OXY-ORTHOTOLYLACRYLIC ACID,
MANUFACTURING PROCESS AND FUNGICIDES CONTAINING THEM
The present invention relates to oxime ethers of the general formula I in the form of racemic mixtures thereof or isomers thereof
wherein
R1 is hydrogen, C1-4alkyl, C1- 3 alkoxymethyl, methylthio, cyano, cyclopropyl or trifluoromethyl,
R2 and R3 together with the two carbon atoms to which they are bonded form an
unsubstituted or substituted five- to seven-membered ring comprising 1 or 2 oxygen atoms, and
X is a single bond, -C(R)2-, CO, -CR=CR-, C(R)2O, C(R)2S or C(R)2C(R 2, in which
R is hydrogen and/or C1-3alkyl, with the proviso that X is one of the groups
-C(R)2-, -CR=CR-, C(R)2O, C(R)2S and C(R)2C(R)2, if
R1 is methyl and R2 and R3 together are methylenedioxy.
The compounds according to the invention have fungicidal properties and are suitable as fungicidal active ingredients, especially for use in agriculture and horticulture.
The invention relates also to a process for the preparation of the compounds according to the invention, to fungicidal compositions comprising such compounds as active ingredients, and to the use of such compounds and compositions for controlling phytopathogenic fungi in agriculture and horticulture.
In the above formula I and hereinafter, alkyl or alkoxy groups are, depending on the number of carbon atoms, straight-chained or branched.
Substituents of the oxygen-containing ring are, for example, C1- 4alkyl, C1- 4alkoxy and fluorine; there may be several such substituents which may be identical or different.
Oxime ethers in which the five- to seven-membered ring formed by R2 and R3 is mono- or poly-substituted by C1-C4alkyl, C1-C4alkoxy and/or by fluorine are therefore preferred. (Sub-group IA).
If asymmetric carbon atoms are present in the compounds of formula I, the compounds occur in optically active form. The compounds in any case occur in the [E] or the [Z] form simply as a result of the presence of the aliphatic and the imino double bond. In addition, atropic isomerism may occur. Formula I is to include all those possible isomeric forms and mixtures thereof, for example racemic mixtures and any [E/Z] mixtures.
The process according to the invention for the preparation of the compounds according to the invention comprises reacting an oxime of the general formula π
wherein R1, R2, R3 and X are as defined above, with a benzyl alcohol derivative of the general formula III
wherein U is a leaving group.
This reaction is a nucleophilic substitution which can be carried out under reaction conditions that are customary in this respect. The leaving group U present in the benzyl alcohol derivative of formula III is preferably to be understood as being chlorine, bromine, iodine, methanesulfonyloxy, benzenesulfonyloxy or p-toluenesulfonyloxy. The reaction is advantageously carried out in a basic medium in an inert organic diluent which may be, especially, aliphatic and aromatic, unsubstituted or halogenated hydrocarbons, such as pentane, hexane, heptane, cyclohexane, petroleum ether, petroleum, ligroin, benzene, toluene, methylene chloride, ethylene chloride, chloroform, carbon tetrachloride, chlorobenzene, o-dichlorobenzene, also ethers, such as diethyl and dibutyl ether, glycol dimethyl ether and diglycol dimethyl ether, tetrahydrofuran and dioxane, also ketones, such as acetone, methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone, also nitriles, such as, for example, acetonitrile and propionitrile, benzonitrile, glutaric acid dinitrile, and, in addition, amides, such as, for example, dimethylformamide, dimethylacetamide and N-methylpyrrolidone, as well as dimethyl sulfoxide, tetramethylenesulfone and hexamethylphosphoric acid triamide.
There may be mentioned as bases: hydroxides, hydrogen carbonates, carbonates and alcoholates of alkali and alkaline earth metals (Li, Na, K, Ca, Mg), sodium hydride, tertiary amines, such as trimethylamine and triethylamine, pyridine, picolines, N-methylmorpholine, N-ethylpyrrolidine, diazabicyclo[4,3,0]undecane (DBU), 1,4-diazabicyclo2,2,2-octane (DABCO), diazabicyclo[3,2,0]nonane (DBN), and organolithium
compounds, such as n-butyllithium.
Furthermore, silver oxide can be used as a catalytically active weak base. The reaction temperature is advantageously in the range of from -20°C to +80°C, preferably from 0°C to +60°C.
Alternatively, the reaction can be carried out with phase transfer catalysis in an organic solvent, such as, for example, methylene chloride, in the presence of an aqueous basic solution, for example sodium hydroxide solution, and a phase transfer catalyst, such as, for example, tetrabutylammonium hydrogen sulfate, at room temperature.
The isolation and purification of the compounds of formula I so obtained can be effected in accordance with methods known per se. Any isomeric mixtures obtained, for example E/Z isomeric mixtures, can be separated into the pure isomers likewise by methods known
per se, for example by chromatography or fractional crystallisation.
The oximes of formula II used as starting materials in the process according to the invention either are known or can be prepared in accordance with methods known per se, for example by reacting the corresponding carbonyl compound R1R2C=O with hydroxyl- amine hydrochloride in the presence of a base, for example sodium or potassium hydroxide or pyridine. Other methods can be found in Houben-Weyl, "Methoden der Organischen Chemie", Vol. X/ 4, pages 3-308 (1968) ("Herstellung und Umwandlung von Oximen" (Preparation and conversion of oximes)). The present invention relates likewise to those compounds of formula H that are novel.
The starting materials of formula m can also be prepared in a manner known per se, for example as described in European Patent Publication No. 203 606 and in the literature cited therein.
An important group of compounds within formula I or the above-mentioned sub-group IA comprises those oxime ethers in which R2 and R3 together are a methylenedioxy or ethylenedioxy bridge bonded by way of oxygen to the phenyl ring, which bridge may be mono- or poly-substituted by methyl, methoxy and/or by fluorine, while R1, X and R are as defined. (Sub-group IB).
Within that group, preferred compounds are those in which X is a single bond or one of the groups -C(R)2-, -CO-, CR2O and CR2CR2, and especially those in which R1 is methyl, isopropyl, methoxymethyl, cyclopropyl or CF3.
Another preferred group within sub-group IB comprises those compounds in which X is one of the groups -CR=CR- and -C(R)2S-, and especially those in which R1 is methyl, isopropyl, methoxymethyl, cyclopropyl or CF3. (Sub-group lb).
Another important group of compounds comprises oxime ethers of formula I or IA in which R2 and R3 together with the two carbon atoms to which they are bonded form a five-membered ring comprising one oxygen atom or a seven-membered ring comprising two oxygen atoms, which rings are unsubstituted or mono- or poly-substituted by methyl, methoxy and/or by fluorine, while R1, X and R are as defined. (Sub-group IC.)
Oxime ethers of formula I or of sub-group IA in which R2 and R3 together with the phenyl
ring to which they are bonded form a benzo-1,3-dioxane ring, while R1, X and R are as defined, also constitute an important range of compounds. (Sub-group ID.)
Compounds nos. 2, 3, 4, 15, 16, 17, 21, 23, 37 and 38 listed in the following Table 1 may be mentioned among the especially preferred compounds.
Typical examples of the novel compounds of the present invention are given in the following Table 1.
The compounds according to the invention have fungicidal action and can accordingly be used to control or prevent fungus infestation in agriculture, in horticulture and in wood protection. They are especially suitable for inhibiting the growth of or for destroying phytopathogenic fungi on parts of plants, for example leaves, stems, roots, tubers, fruit or blossom, and on seed, as well as noxious fungi occurring in the soil. The compounds according to the invention can also be used to control fungi that cause wood to decompose or to become discoloured. The compounds according to the invention are effective, for example, in the control of fungi of the classes Deuteromycetes, Ascomycetes, Basidiomycetes and Phycomycetes.
The compounds according to the invention are especially suitable for controlling the following pathogens:
True mildew fungi (for example Erysiphe graminis, Erysiphe cichoracearum, Podosphaera leucotricha, Uncinula necator, Sphaerotheca spp.)
Rust fungi (for example Puccinia tritici, Puccinia recondita, Puccinia hordei, Puccinia coronata, Puccinia striiformis, Puccinia arachidis, Hemileia vastatrix, Uromyces fabae)
Scab fungi (for example Venturia inaequalis)
Cercospora spp. (for example Cercospora arachidicola, Cercospora beticola)
Mycosphaerella spp. (for example Mycosphaerella fijiensis)
Alternaria spp. (for example Alternaria brassicae, Alternaria mali)
Septoria spp. (for example Septoria nodorum)
Helminthosporium spp. (for example Helminthosporium teres, Helminthosporium oryzea)
Plasmopara spp. (for example Plasmopara viticola)
Pseudoperonospora spp. (for example Pseudoperonospora cubensis)
Phytophthora spp. (for example Phytophthora infestans)
Pseudocercosporella spp. (for example Pseudocercosporella herpotrichoides)
Piricularia spp. (for example Piricularia oryzae)
The compounds are also effective against, for example, fungi of the genera Tilletia, Ustilago, Rhizoctonia, Verticillium, Fusarium, Pythium, Gaeumannomyces, Sclerotinia, Monilia, Botrytis, Peronospora, Bremia, Gloeosporium, Cercosporidium, Penicillium, Ceratocystis, Rhynchosporium, Pyrenophora, Diaporthe, Ramularia and Leptosphaeria. Certain representatives of the compounds according to the invention are also effective
against wood-destructive fungi, such as, for example, of the genera Coniophora, Gloeophyllum, Poria, Merulius, Trametes, Aureobasidium, Sclerophoma and Trichoderma.
The compounds according to the invention are distinguished by a prophylactic and curative action, but especially by a marked systemic action.
The compounds according to the invention are effective against phytopathogenic fungi under greenhouse conditions at concentrations as low as from 0.5 mg to 500 mg of active ingredient per litre of spray mixture. Under field conditions it is advantageous to use concentrations of from 20 g to 1 kg of compound of formula I per hectare and treatment. In order to control seed-borne and soil-borne fungi by the seed-dressing process, it is advantageous to use concentrations of from 0.001 g to 1.0 g of compound of formula I per kg of seed.
The compounds according to the invention can be formulated into a variety of compositions, for example solutions, suspensions, emulsions, emulsifϊable concentrates and pulverulent preparations. The fungicidal compositions according to the invention comprise an effective amount of at least one compound of the general formula I, as defined above, and formulation auxiliaries. The compositions advantageously comprise at least one of the following formulation auxiliaries:
Solid carriers; solvents or dispersion agents; surfactants (wetting agents and emulsifiers); dispersion agents (without surfactant action); and stabilisers.
Suitable solid carriers are essentially: natural mineral substances, such as kaolin, argillaceous earths, kieselguhr, talcum, bentonite, chalk, for example prepared chalk, magnesium carbonate, limestone, quartz, dolomite, attapulgite, montmorillonite and diatomaceous earth; synthetic mineral substances, such as highly dispersed silicic acid, aluminium oxide and silicates; organic substances, such as cellulose, starch, urea and synthetic resins; and fertilisers, such as phosphates and nitrates, it being possible for such carriers to be present, for example, in the form of granules or powders.
Suitable solvents and dispersion agents are essentially: aromatic compounds, such as toluene, xylenes, benzene and alkylnaphthalenes; chlorinated aromatic compounds and chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes and methylene chloride; aliphatic hydrocarbons, such as cyclohexane and paraffins, for
example crude oil fractions; alcohols, such as butanol and glycol, as well as the ethers and esters thereof; ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; and strongly polar solvents and dispersion agents, such as dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide, such solvents and dispersion agents preferably having flash points of at least 30°C and boiling points of at least 50°C, and water. Other suitable solvents and dispersion agents are so-called liquefied gaseous extenders or carriers, which are products that are gaseous at room temperature and under normal pressure. Examples of such products are especially aerosol propellants, such as (halo)hydrocarbons. If water is used as the solvent, it is also possible to use, for example, organic solvents as auxiliary solvents.
The surfactants (wetting agents and emulsifiers) may be non-ionic compounds, such as condensates of fatty acids, fatty alcohols or fatty-substituted phenols with ethylene oxide; fatty acid esters and ethers of sugars or polyhydric alcohols; the products that are obtained from sugars or polyhydric alcohols by condensation with ethylene oxide; block copolymers of ethylene oxide and propylene oxide; or alkyl dimethyl aminoxides.
The surfactants may also be anionic compounds, such as soaps; fatty sulfate esters, for example dodecylsodium sulfate, octadecylsodium sulfate and cetylsodium sulfate; alkyl sulfonates, aryl sulfonates and fatty aromatic sulfonates, such as alkylbenzenesulfonates, for example calcium dodecylbenzenesulfonate, and butylnaphthalenesulfonates; and more complex fatty sulfonates, for example the amide condensates of oleic acid and N-methyltaurin and the sodium sulfonate of dioctyl succinate.
Finally, the surfactants may be cationic compounds, such as alkyldimethylbenzylammonium chlorides, dialkyldimethylammonium chlorides, alkyltrimethylammonium chlorides and ethoxylated quaternary ammonium chlorides.
Suitable dispersion agents (without surfactant action) are essentially: lignin, sodium and ammonium salts of lignosulfonic acid, sodium salts of maleic acid anhydride-diisobutylene copolymers, sodium and ammonium salts of sulfonated polycondensates of naphthalene and formaldehyde, and sulfite waste liquors.
There may be used as dispersion agents that are especially suitable as thickeners or anti-settling agents, for example, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, alginates, caseinates and blood albumin.
Examples of suitable stabilisers are acid-forming agents, for example epichlorohydrin, phenyl glycidyl ethers and soya epoxides; anti-oxidants, for example gallic acid esters and butylhydroxytoluene; UV-absorbers, for example substituted benzophenones, diphenyl- acrylonitrilic acid esters and cinnamic acid esters; and deactivators, for example salts of ethylenediaminetetraacetic acid and polyglycols.
The fungicidal compositions according to the invention may, in addition to the compounds of formula I, also comprise other active ingredients, for example other types of fungicidal composition, insecticidal and acaricidal compositions, bactericides, plant growth regulators and fertilisers. Such combined compositions are suitable for broadening the activity spectrum, or for influencing plant growth in a specific manner.
The fungicidal compositions according to the invention, depending on their type, generally comprise from 0.0001 to 95 % by weight of compound(s) according to the invention as active ingredient(s). They may be in a form suitable for storage and transport. In such forms, for example emulsifiable concentrates, the active ingredient concentration is normally in the upper region of the above concentration range. Those forms can then be diluted with the same or different formulation auxiliaries to give active ingredient concentrations suitable for practical use, and such concentrations normally lie in the lower region of the above concentration range. Emulsifiable concentrates generally comprise from 5 to 85 % by weight, preferably from 25 to 75 % by weight, of the compound(s) according to the invention. Suitable forms of application are, inter alia, ready-for-use solutions, emulsions and suspensions, which are suitable, for example, as spray mixtures. The concentration of active ingredient in such spray mixtures may be, for example, from 0.0001 to 20 % by weight. In the ultra-low-volume process, spray mixtures may be formulated in which the active ingredient concentration is preferably from 0.5 to 20 % by weight, while the spray mixtures formulated in the low-volume process and in the high-volume process preferably have an active ingredient concentration of from 0.02 to 1.0 % by weight and from 0.002 to 0.1 % by weight, respectively.
The fungicidal compositions according to the invention can be prepared by mixing at least one compound according to the invention with formulation auxiliaries.
The compositions can be prepared in known manner, for example by mixing the active ingredients with solid carriers, by dissolving or suspending in suitable solvents or
dispersion agents, optionally with the use of surfactants as wetting agents or emulsifiers or of dispersion agents, by diluting pre-prepared emulsifiable concentrates with solvents or dispersion agents, etc..
In the case of pulverulent compositions, the active ingredient can be mixed with a solid carrier, for example by grinding them with one another; alternatively the solid carrier can be impregnated with a solution or suspension of the active ingredient and then the solvent or dispersion agent can be removed by evaporation, heating or by filtering with suction under reduced pressure. By the addition of surfactants or dispersion agents, such pulverulent compositions can be rendered readily wettable with water so that they can be converted into aqueous suspensions which are suitable, for example, as spraying compositions.
The compounds according to the invention can also be mixed with a surfactant and a solid carrier to form a wettable powder that is dispersible in water, or they can be mixed with a solid pre-granulated carrier to form a product in granule form.
If desired, a compound according to the invention can be dissolved in a water-immiscible solvent, such as, for example, an alicyclic ketone, which advantageously contains dissolved emulsifier, so that the solution has self-emulsifying action when added to water. Alternatively, the active ingredient can be mixed with an emulsifier and the mixture can then be diluted with water to the desired concentration. In addition, the active ingredient can be dissolved in a solvent and then mixed with an emulsifier. Such a mixture can also be diluted with water to the desired concentration. In that manner, emulsifiable
concentrates or ready-for-use emulsions are obtained.
The compositions according to the invention can be used in accordance with the methods of application customary in plant protection or in agriculture. The method according to the invention of controlling fungi comprises treating the material to be protected, for example plants, parts of plants, or seed, with an effective amount of a compound according to the invention or of a composition according to the invention.
The following Examples illustrate the invention.
Preparation of the compounds of formula I:
Example 1 59.92 g (0.21 mol) of 2-(α-bromo-o-tolyl)-3-methoxyacrylic acid methyl ester and 40.6 g (0.21 mol) of 3,4-ethylenedioxyacetophenoneoxime in 210 ml of methylene chloride are stirred intensively at room temperature for 10 minutes with 210 ml of 2.2N sodium hydroxide solution and 92.3 g of tetrabutylammonium hydrogen sulfate. Then the same amounts of methylene chloride, 2.2N sodium hydroxide solution and tetrabutylammonium hydrogen sulfate are added and the batch is stirred for a further 10 minutes. The same amounts of 2.2N sodium hydroxide solution and tetrabutylammonium hydrogen sulfate are then added again, followed, after a further 10 minutes' stirring, by saturated sodium hydrogen carbonate solution.
The mixture is extracted three times with 150 ml of ethyl acetate each time, and the combined organic phases are washed with saturated sodium chloride solution and dried over anhydrous sodium sulfate. After removing the solvent by distillation, the oil that remains is purified by chromatography on silica gel using n-hexane/diethyl ether (3:2) as eluant.
Recrystallisation from diethyl ether/n-hexane yields [E]-3-methoxy-2-[α-{[(α-methyl- 3,4-ethylenedioxybenzyl)imino]oxy}-o-tolyl]-acrylic acid methyl ester in the form of colourless crystals, m.p. 97-98°C. [Comp. No. 2]
The compounds listed in Table 1 can be prepared in an analogous manner.
Formulation Examples
F1:
An emulsifiable concentrate has, for example, the following composition:
g/litre
compound of Table 1 100
nonylphenol-(10)ethoxylate
(non-ionic emulsifier) 50
calcium dodecylbenzenesulfonate
(anionic emulsifier) 25
N-methyl-2-pyrrolidone (solubiliser) 200
mixture of alkylbenzenes (solvent) ad 1 litre
The active ingredient and the emulsifiers are dissolved in the solvent and in the solubiliser. A ready-for-use spray mixture of any desired dilution can be prepared by emulsifying this concentrate in water. F2:
A wettable powder has, for example, the following composition:
% by weight
compound of Table 1 25.0 silicic acid (hydrated; carrier) 20.0 sodium laurylsulfate (wetting agent) 2.0 sodium lignosulfonate (dispersion agent) 4.0 kaolin (carrier) 49.0
The components are mixed with one another and finely ground in a suitable mill. A suspension that is suitable as a ready-for-use spray mixture is produced by dispersing the mixture in water.
Biological Examples:
Example BI: Action against Puccinia graminis in wheat
a) Residual-protective action
Wheat plants are sprayed 6 days after sowing with a spray mixture (0.02 % active ingredient) prepared from a wettable powder formulation of the test compound. After 24 hours the treated plants are infected with a uredospore suspension of the fungus. The infected plants are incubated for 48 hours at 95-100 % relative humidity and about 20°C and then stood in a greenhouse at about 22°C. Evaluation of rust pustule development is made 12 days after infection. b) Systemic action
Wheat plants are watered 5 days after sowing with a spray mixture (0.006 % active ingredient, based on the volume of the soil) prepared from a wettable powder formulation of the test compound. After 48 hours the treated plants are infected with a uredospore suspension of the fungus. The infected plants are then incubated for 48 hours at 95-100 %
relative humidity and about 20°C and then stood in a greenhouse at about 22°C.
Evaluation of rust pustule development is made 12 days after infection.
Puccinia attack is 100 % on untreated and infected control plants. Compounds of Table 1 exhibit good activity against Puccinia fungi. The following compounds inhibit Puccinia infestation to less than 20 %: nos. 1, 2, 3, 9, 10, 13, 15, 16, 21, 23, 36, 37, 38, 39, 41, 42, 43 and 44.
Example B2: Action against Cercospora arachidicola on
groundnut plants
a) Residual-protective action
Groundnut plants 10-15 cm in height are sprayed with a spray mixture (0.02 % active ingredient) prepared from a wettable powder formulation of the test compound, and infected 48 hours later with a conidia suspension of the fungus. The infected plants are incubated for 72 hours at about 21°C and high humidity and then stood in a greenhouse until the typical leaf specks occur. Evaluation of the fungicidal action is made 12 days after infection and is based on the number and size of the specks. b) Systemic action
Groundnut plants 10-15 cm in height are watered with a spray mixture (0.06 % active ingredient, based on the volume of the soil) prepared from a wettable powder formulation of the test compound. The treated plants are infected 48 hours later with a conidia suspension of the fungus and then incubated for 72 hours at about 21°C and high humidity. The plants are then stood in a greenhouse and evaluation of fungus infestation is made 11 days later.
Compared with untreated and infected control plants (number and size of the specks = 100 %), Cercospora infestation on groundnut plants treated with compounds of Table 1 is substantially reduced. The Cercospora infestation is inhibited to less than 20 % with compounds nos. 1, 2, 3, 10, 11, 12, 13, 15, 16, 21, 23, 36, 37, 38, 39, 41, 42, 43, 44, 57, 58 and 59.
Example B3: Action against Erysiphe graminis on barley
a) Residual-protective action
Barley plants about 8 cm in height are sprayed with a spray mixture (0.02 % active ingredient) prepared from a wettable powder formulation of the test compound. The
treated plants are dusted with conidia of the fungus after 3 to 4 hours. The infected barley plants are stood in a greenhouse at about 22°C. The fungus attack is evaluated after 10 days. b) Systemic action
A spray mixture (0.006 % active ingredient, based on the volume of the soil) prepared from a wettable powder formulation of the test compound is used to water barley plants about 8 cm in height. Care is taken that the spray mixture does not come into contact with the parts of the plants above the soil. The treated plants are dusted 48 hours later with conidia of the fungus. The infected barley plants are then stood in a greenhouse at about 22°C and evaluation of fungus infestation is made after 10 days.
Compounds of formula I exhibit good activity against Erysiphe fungi. The Erysiphe infestation is 100 % on untreated and infected control plants. The fungus infestation in barley is substantially inhibited by compounds of Table 1. The fungus infestation is inhibited to 0-5 % by compounds nos. 1, 3, 4, 10, 11, 13, 15, 16, 21, 37, 38, 39, 41, 42, 43, 44, 59 and 61.
Example B4: Residual-protective action against Venturia
inaequalis on apple shoots
Apple cuttings with 10-20 cm long fresh shoots are sprayed with a spray mixture (0.06 % active ingredient) prepared from a wettable powder formulation of the test compound. The treated plants are infected 24 hours later with a conidia suspension of the fungus. The plants are then incubated for 5 days at 90-100 % relative humidity and stood in a greenhouse for a further 10 days at 20-24°C. Scab infestation is evaluated 15 days after infection. Compounds of Table 1 inhibit the Venturia infestation to a substantial degree. Compounds nos. 1, 3, 21, 36, 37, 38, 39, 41, 42, 43, 44 and others limit the infestation to less than 20 %.
Example B5: Action against Botrytis cinerea on beans.
Residual-protective action
Bean plants about 10 cm in height are sprayed with a spray mixture (0.02 % active ingredient) prepared from a wettable powder formulation of the test compound. After 48 hours the treated plants are infected with a conidia suspension of the fungus. The infected plants are incubated for 3 days at 95-100 % relative humidity and 21°C and then evaluated for fungus infestation.
The Botrytis infestation on untreated and infected bean plants is 100 %. After treatment with one of compounds nos.4, 13, 17, 21, 23, 24, 28, 36, 59 and 61 of formula I, the infestation is less than 20 %.
Example B6: Action against Rhizoctonia solani (soil fungus on rice plants)
a) Protective-local soil application
A spray mixture prepared from a formulation of the test compound (0.006 % active ingredient) is used to water 12-day-old rice plants without wetting the parts of the plants above the soil. A suspension of mycelium and sclerotia of R. solani is applied to the surface of the soil in order to infect the treated plants. The plants are incubated for 6 days at 27°C (day) and 23°C (night) and 100 % relative humidity (humidity box) in a climatic chamber and then evaluation is made of the fungus infestation on the leaf sheath, leaves and stems. b) Protective-local foliar application
12-day-old rice plants are sprayed with the spray mixture mentioned under a). The treated plants are infected one day later with a suspension of mycelium and sclerotia of R. solani. The plants are incubated for 6 days at 27°C (day) and 23°C (night) and 100 % relative humidity (humidity box) in a climatic chamber and then evaluation is made of the fungus infestation on the leaf sheath, leaves and stems.
Compounds of Table 1 exhibit good activity by inhibiting the Rhizoctonia infestation. By contrast, infestation is 100 % on the untreated and infected control plants. The fungus infestation is inhibited to substantially below 20 % by compounds nos. 2, 9, 17, 23, 24, 59, 61 and 63.
Example B7: Action against Phytophthora infestans on tomatoes
a) Curative action
Tomato plants of the "Roter Gnom" variety are reared for three weeks and then sprayed with a zoospore suspension of the fungus and incubated in a chamber at 18 to 20°C and saturation humidity. Humidity is discontinued after 24 hours. When the plants have dried they are sprayed with a mixture comprising a wettable powder formulation of the test compound at a concentration of 200 ppm. After the spray coating has dried, the plants are placed in the humidity chamber again for 4 days. The number and size of the typical leaf specks that have occurred after this period are used as a standard for evaluating the
activity of the test compounds. b) Preventive systemic action
A wettable powder formulation of the test compound is applied at a concentration of 60 ppm (based on the volume of the soil) to the soil surface of three-week-old tomato plants of the "Roter Gnom" variety in pots. After a waiting period of three days, the undersides of the leaves are sprayed with a zoospore suspension of Phytophthora infestans. They are then kept in a spray chamber for 5 days at 18 to 20°C and saturation humidity. At the end of this period typical leaf specks form, the number and size of which are used to evaluate the activity of the test compounds.
Compounds of Table 1, for example compounds nos. 4, 9, 11, 13, 15, 16, 17, 23, 24, 28, 36, 57, 59, 61, 62 and 63, inhibit the Phytophthora infestation to less than 20 %.
Example B8: Action against Plasmopara viticola (Bert, et Curt.) (Berl. et Detoni) on vines a) Residual-preventive action
Vine cuttings of the "Chasselas" variety are reared in a greenhouse. At the 10-leaf stage, 3 plants are sprayed with a mixture (200 ppm active ingredient) prepared from a wettable powder formulation of the test compound. After the spray coating has dried, the undersides of the leaves are uniformly infected with a spore suspension of the fungus. The plants are then kept for 8 days in a humidity chamber. At the end of this period clear symptoms of the disease appear on the control plants. The number and size of the infected sites on the treated plants are used as a standard for evaluating the activity of the test compounds. b) Curative action
Vine cuttings of the "Chasselas" variety are reared in a greenhouse and, at the 10-leaf stage, the undersides of the leaves are infected with a spore suspension of Plasmopara viticola. After 24 hours in the humidity chamber, the plants are sprayed with an active ingredient mixture prepared from a wettable powder formulation of the test compound (500 ppm active ingredient). The plants are then kept for a further 7 days in the humidity chamber. At the end of this period, the symptoms of the disease appear on the control plants. The number and size of the infected sites on the treated plants are used as a standard for evaluating the activity of the test compounds.
The compounds of formula I, especially compounds nos. 1, 2, 3, 4, 9, 10, 11, 13, 15, 16,
17, 23, 24, 28, 36, 37, 38, 41, 42, 43, 44, 56, 57, 58, 59, 60, 61, 62 and 63, strongly inhibit the Plasmopara infestation to, in some cases, less than 10 %.
Example B9: Action against Pythium debaryanum on sugarbeet
(Beta vulgaris)
a) Action after soil application
The fungus is cultivated on sterile oat grains and added to a mixture of earth and sand. The earth so infected is introduced into flowerpots and sown with sugarbeet seeds. Immediately after sowing, an aqueous suspension (20 ppm active ingredient based on the volume of the earth) prepared from a wettable powder formulation of the test preparation is poured over the earth. The pots are then stood in a greenhouse at 20-24°C for 2-3 weeks. The earth is kept constantly and uniformly moist by light spraying with water. The test is evaluated by determining the rate of emergence of the sugarbeet plants and the proportion of healthy and diseased plants. b) Action after dressing application
The fungus is cultivated on sterile oat grains and added to a mixture of earth and sand. The earth so infected is introduced into flowerpots and sown with sugarbeet seed which has been dressed with a dressing powder formulation of the test preparation (1000 ppm active ingredient based on the weight of the seed). The pots containing the seeds are stood in a greenhouse for 2-3 weeks at 20-24°C. The earth is kept uniformly moist by light spraying with water. The test is evaluated by determining the rate of emergence of the sugarbeet plants and the proportion of healthy and diseased plants.
A rate of emergence of more than 80 % is achieved with compounds of Table 1. The corresponding control plants have a rate of emergence of less than 30 % and an unhealthy appearance.