GB2199748A - Microbicidal compositions - Google Patents

Abstract

A combination of the plant microbicide 1,2,5,6-tetrahydro-4H-pyrrolo[3,2,1-i,j]quinolin-4-one (pyroquilon) and the plant microbicide 1-[2-(2',4'-dichlorophenyl)-4-propyl- 1,3-dioxolan-2-yl-methyl]-1H-1,2,4-triazole (propiconazol) results in a synergistically enhanced activity in the control of plant diseases. Microbicidal compositions based on such combinations are especially suitable for controlling rice diseases.

Description

Microbicidal compositions The present invention relates to microbicidal mixtures enhanced synergistic activity against plant diseases and to methods of applying said mixtures.

Specifically, the present invention relates to the control and prevention of diseases in rice crops.

It has been found that a combination of component I, 1,2,5,6-tetra hydro-4H-pyrrolo[ 3,2, 1-i,j quinolin-4-one ("pyroquilon") of formula I

and component II, l-L2-(2',4'-dichlorophenyl)-4-propyl-1,3-dioxolan- 2-ylmethyll-lH-1,2,4-triazole ("propiconazol") of formula II

or a salt thereof, leads to a synergistically enhanced activity in controlling and preventing plant diseases.

Propiconazol (component II) can exist in four stereoisomeric forms, each having different fungicidal activity. The two cis-isomers are preferred, i.e. those enantiomers in which the triazolylmethyl group and the propyl group are situated on the same side of the dioxolane ring.

The invention also encompasses in particular compositions and appropriate methods of application in which component II, propiconazol, is used preponderantly as one of the cis-isomers together with component I, pyroquilon.

The acids which may be used for obtaining salts of formula II are typically: hydrohalic acids such as hydrofluoric acid, hydrochloric acid, hydrobromic acid or hydriodic acid, as well as sulfuric acid, phosphoric acid and nitric acid; and organic acids such as acetic acid, trifluoroacetic acid, trichloroacetic acid, propionic acid, glycolic acid, thiocyanic acid, lactic acid, succinic acid, citric acid, oxalic acid, formic acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, salicylic acid, p-aminosalicylic acid, 2-phenoxybenzoic acid, 2-acetoxybenzoic acid or 1,2-naphthalenedisulfonic acid.

The term "salt" also comprises metal complexes of the basic component II. These complexes consist of the basic organic molecule and an inorganic or organic metal salt, for example the halides, nitrates, sulfates, phosphates, acetates, trifluoroacetates, trichloroacetates, propionates, tartrates, sulfonates, salicylates, benzoates and the like of elements of the second main group of the Periodic Table, for example calcium and magnesium, and of the third and fourth main group, for example aluminium, tin or lead, as well as of the first to eighth auxiliary group, for example chromium, manganese, iron, cobalt, nickel, copper, zinc and the like. Preferred elements are those of the auxiliary groups of the fourth period. The metals may exist in different valence states.The metal complexes can be mononuclear or polynuclear, i.e. they can contain one or more parts of the organic molecule as ligands.

In recent years there has been an intensified search for fungicides that have a systemic action on plants. Pyroquilon (I) as well as propiconazol (II) have a systemic action. By virtue of their capacity to penetrate into the cell structure of the plants and into their sap-flow, they are able to protect all parts of the plants against attack by pathogens or, in the event of attack having already occurred, to prevent the disease from spreading.

Pyroquilon (I) is disclosed as a fungicide in GB patent specification 1 394 373. It acts primarily against Pyricularia oryzae (rice blast) and to a lesser degree against other pathogens of rice diseases.

Propiconazol (II) is disclosed as a fungicide in US patent specification 4 079 062. It has a broad activity against leaf and head diseases in cereals. Although it does act against rice diseases such as Rhizoctonia solani, Cercospora oryzae, Rhynchosporium oryzae, Acrocylindrium oryzae and Helminthosporium, this activity is not entirely satisfactory.

Surprisingly, it has now been found that a combination of both fungicides results in a quite unexpectedly pronounced increase in activity which even makes it possible to lower the rate of application of the total combination to less than 500 g a.i./ha and still to achieve full activity against diseases of cereals, especially rice diseases.

Hence the present invention constitutes a very substantial enrichment of the art.

Useful mixture ratios of the two active ingredients are: I:II = 25:1 to 1:25, especially I:II = 25:1 to 1:5, preferably 1:11 = 10:1 to 1:1.

Particularly preferred ratios are in the ranges (depending on the type of application and the pathological system) I:II = 4:1 to 3:2, e.g. 1:11 = 5:2, I:II = 6:5 or also I:II = 12:5.

The combinations of I + II of this invention have very useful curative, preventive and systemic fungicidal properties for protecting cultivated plants. With these combinations it is possible to inhibit or destroy the microorganisms which occur in plants or parts of plants (fruit, blossoms, leaves, stems, tubers, roots) in different crops of useful plants, while at the same time the parts of plants which grow later are also protected from attack by such microorganisms.

The combinations are effective against the phytopathogenic fungi belonging to the following classes: Ascomycetes (e.g. Venturia, Podosphaera, Erysiphe, Monilinia, Uncinula): Basidiomycetes (e.g. the genera Hemileia, Rhizoctonia, Puccinia); Fungi imperfecti (e.g. Botrytis, Helminthosporium, Fusarium, Septoria, Cercospora, Alternaria and, especially, Pyricularia). The combinations of this invention are especially well tolerated by plants, in particular by the rice varieties known to be sensitive. No phytotoxicity was observed in treated cereals plants, especially in rice plants, treated with spray mixture at the concentrations of 100-500 g a.i./ha necessary for the effective control and prevention of plant diseases.

Suitable carriers and adjuvants in the compositions of this invention can be solid or liquid and correspond to the substances ordinarily employed in formulation technology, e.g. natural or regenerated mineral substances, solvents, dispersants, wetting agents, tackifiers, thickeners, binders or fertilisers.

The combinations are therefore formulated in known manner e.g. to emulsifiable concentrates, coatable pastes, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granulates, and also encapsulations in e.g. polymer substances, as has already been described in connection with the individual compounds. As with the nature of the compositions, the methods of application, such as spraying, atomising, dusting, scattering, coating or pouring, are chosen in accordance with the intended objectives and the prevailing circumstances.

A preferred method of applying a combination which contains at least one of components I and II is application to the growing parts of plants, especially the leaves (foliar application). The number of applications and the rate of application depend on the biological and climatic life conditions of the pathogen. However, the active components can also penetrate the plant through the roots via the soil (systemic action) by drenching the locus of the plant with a liquid formulation, or by applying the compounds in solid form to the soil, e.g. in granular form (soil application). In addition, further methods of application to plants are possible in special cases, e.g. selective treatment of buds or infructescences (e.g.

panicles). It is also possible to treat the seed beds employed for growing water rice plants very successfully with the combination.

Useful rates of application are generally from 100 g to 1 kg a.i./ha, preferably 100 g to 600 g-a.i.lha, where a.i. will be understood as meaning the total amount of compounds I and II.

The formulations are prepared in known manner, e.g. by homogeneously mixing and/or grinding the active ingredients with extenders, e.g.

solvents, solid carriers and, where appropriate, surface-active compounds (surfactants).

Suitable solvents are: aromatic hydrocarbons, preferably the fractions containing 8 to 12 carbon atoms, e.g. xylene mixtures or substituted naphthalenes, phthalates such as dibutyl phthalate or dioctyl phthalate, aliphatic hydrocarbons such as cyclohexane or paraffins, alcohols and glycols and their ethers and esters, such as ethanol, ethylene glycol monomethyl or monoethyl ether, ketones such as cyclohexanone, strongly polar solvents such as N-methyl-2-pyrro lidone, dimethylsulfoxide or dimethylformamide, as well as vegetable oils or epoxidised vegetable oils such as epoxidised coconut oil or soybean oil; or water.

The solid carriers used e.g. for dusts and dispersible powders are normally natural mineral fillers such as calcite, talcum, kaolin, montmorillonite or attapulgite. To improve the physical properties it is also possible to add highly dispersed silicic acid or highly dispersed absorbent polymers. Suitable granulated adsorptive carriers are porous types, for example pumice, broken brick, sepiolite or bentonite; and suitable nonsorbent carriers are materials such as calcite or sand. In addition, a great number of pregranulated materials of inorganic or organic nature can be used, e.g. especially dolomite or pulverised plant residues.Particularly advantageous application promoting adjuvants which are able to reduce substantially the rate of application are also natural (animal or vegetable) or synthetic phospholipids of the series of the cephalins and lecithins, e.g. phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl choline, sphingomyeline, phosphatidyl inisotol, phosphatidyl glycerol, lysolecithin, plasmalogenes or cardiolipin, which can be obtained e.g. from animal or plant cells, in particular from the brain, heart, liver, egg yokes or soya beans.

Examples of useful physical forms are phosphatidyl choline mixtures.

Examples of synthetic phospholipids are dioctanoylphosphatidyl choline and dipalmitoylphosphatidyl choline.

Depending on the nature of the compounds of formulae I and II to be formulated, suitable surface-active compounds are nonionic, cationic and/or anionic sufactants having good emulsifying, dispersing and wetting properties. The term "surfactants" will also be understood as comprising mixtures of surfaxtants.

Furthermore, the present invention also embraces a method of treating plant diseases, which comprises applying the compounds of formulae I and II and the compositions containing them to the locus already infected or in danger of infection. The application of both compounds I and II can be made in any order or simultaneously.

The invention also relates to the preparation of agrochemical compositions, which comprises intimately mixing the active components with one or more carriers or diluents described herein.

Target crops to be protected within the scope of the present invention comprise e.g. the following species of plants: cereals (wheat, barley, rye, oats, rice, sorghum and related crops); beet (sugar beet and fodder beet); drupes, soft fruit and, in particular, pomes, plums, peaches, almonds, cherries, strawberries, raspberries, blackberries, in particular apples and pears); leguminous plants (beans, lentils, peas, soybeans); oil plants (rape, mustard, poppy, olives, sunflowers, coconuts, castor oil plants, cocoa beans, groundnuts), cucumber plants (cucumber, marrows, melons); fibre plants (cotton, flax, hemp, jute); citrus fruit (oranges, lemons, grapefruit, mandarins); vegetables (spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, paprika); lauraceae (avocados, cinnamon, camphor); or plants such as maize, tobacco, nuts, coffee, sugar cane, tea, vines, hops, bananas and natural rubber plants, as well as ornamentals.

The combinations are normally applied in the form of compositions and can be applied to the crop area or plants to be treated, simultaneously or in succession, if desired together with further carriers, surfactants or application promoting adjuvants customarily employed in the art of formulation. These further compounds can be fertilisers as well as micronutrient donors or other substances that influence plant growth. They can also be selective herbicides, insecticides, fungicides, bactericides, nematicides, molluscicides or mixtures of several of these substances.

In the following Formulation Examples, the term "active ingredient" denotes a mixture of pyroquilon I and propiconazol II in the ratio 3:1 to 1:1.

Wettable powders a) b) c) active ingredient 25 % 50 % 75 % sodium lignosulfonate 5 % 5 sodium lauryl sulfate 3 % - 5 % sodium diisobutylnaphthalenesulfonate - 6 % 10 % octylphenol polyethylene glycol ether (7-8 moles of ethylene oxide) - 2 % highly dispersed silicic acid 5 % 10 % 10 % kaolin 62 % 27 % The active ingredient is thoroughly mixed with the adjuvants and the mixtures is thoroughly ground in a suitable mill, affording wettable powders which can be diluted with water to give suspensions of the desired concentration.

Emulsifiable concentrate active ingredient 10 % octylphenol polyethlene glycol ether (4-5 moles of ethylene oxide) 3 % calcium dodecylbenzenesulfonate 3 % castor oil polyglycol ether (36 moles of ethylene oxide) 4 cyclohexanone 30 % xylene mixture 50 % Emulsions of any required concentration can be obtained from this concentrate by dilution with water.

Dusts a) b) active ingredient 5 % 8 % talcum 95 % kaolin - 92 % Ready-for-use dusts are obtained by mixing the active ingredient with the carriers, and grinding the mixture in a suitable mill.

Extruder granulate active ingredient 10 % sodium lignosulfonate 2 % carboxymethylcellulose 1 % kaolin 87 % The active ingredient is mixed and ground with the adjuvants, and the mixture is subsequently moistened with water. The mixture is extruded and then dried in a stream of air.

Coated granulate active ingredient 3 % polyethylene glycol 200 (mol wt.) 3 % kaolin 94 % The finely ground active ingredient is uniformly applied, in a mixer, to the kaolin moistened with polyethylene glycol. Non-dusty coated granulates are obtained in this manner.

Biological Examples Fungicides always have a synergistic effect if the fungicidal activity of the combined formulation is greater than the sum of the activity of the individually applied fungicides.

The expected activity E for a given combined formulation, e.g.

consisting of two fungicides, obeys the COLBY formula and can be calculated as follows (COLBY, L.R. "Calculating synergistic and antagonistic responses-of a herbicide combination", Weeds 15, pp. 20-22), (LINTEL et al., 1062 "Weeds control by ... certain combinations", Proc.NEWCL, Vol. 16, pp. 48-53): (g of a.i./ha = grams of active ingredient per hectolitre of spray mixture) X = percentage activity of fungicide I at a rate of application of p g of a.i./ha Y = percentage activity of fungicide II at a rate of application of q g of a.i./ha E = expected activity of fungicides I + II at a rate of application of p+g g of a.i./ha then according to Colby: E = X + Y - X10OY 100 If the actually observed activity (0) is greater than that calculated, then the activity of the combined formulation is greater than additive, i.e. there is synergism.

Test in water rice The following test was carried out in Japan.

A field of water rice plants, which had been planted from a seed bed on May 28, was divided into plots measuring 10 m2. An aqueous solution of a specic concentration of compound I or II or a combination of I and II was sprayed on to the plants on July 4, July 11, August 28 and September 3 (foliar treatment). Evaluation was made 91 days after the first application (the untreated control plants were naturally infested by Helminthosporium oryzae and Piricularia oryzae). The individual results were as follows: Compound g of a.i./ha Activity against Helminthosporium (%) E O I (pyroquilon) 300 g - 62 150 g - 33 II (propiconazol) 300 g - 70 125 g - 48 I + II 300 g + 125 g 80 95 150 g + 125 g 65 97 As is evident, a synergistically enhanced fungicidal activity of 95 % and 97 % was achieved at quite different mixture ratios.

The treated plots exhibited no Pyricularia attack.

Claims (9)

What is claimed is:

1. A microbicidal composition comprising at least two active components, wherein one component (I) is 1,2,5,6-tetrahydro-4H pyrrolo[3,2,1-i,jjquinolin-4-one of formula I

and the other component (II) is 1-[2-(2',4'-dichlorophenyl)-4-prop- yl-1,3-dioxolan-2-ylmethyl]-lH-1,2,4-triazole of formula II

or a salt thereof, together with a suitable carrier therefor.

2. A composition according to claim 1, wherein the weight ratio of I:II is 25:1 to 1:25.

3. A composition according to claim 2, wherein the weight ratio of I:II is 25:1 to 1:5.

4. A composition according to claim 3, wherein the weight ratio of 1:11 is 10:1 to 1:1.

5. A composition according to claim 1, which contains component II preponderantly or completely as cis-enantiomer.

6. P method of controlling or preventing plant diseases at a locus, which comprises treating the locus which is already infected or is liable to be infected, in any order or simultaneously, at least with one compound of formula I and one compound of formula II according to claim 1.

7. A method according to claim 6, which comprises treating rice plants or the locus thereof.

8. A composition according to claim 1 substantially as described with reference to any of the Formulation Examples.

9. A method according to claim 6 substantially as described with reference to any of the Biological Examples.