GB2264641A - Fungicidal compositions - Google Patents

Abstract

Combinations of cyproconazole with flutriafol and combinations of either of these active ingredients with a sterol biosynthesis inhibitor belonging to the triazole family exhibit synergistic fungicidal activity against phytopathogenic fungi. Favorable biological properties are suggesting an application of these combinations for example in cereals. The sterol biosynthesis inhibitors include flutriafol, flusilazole, hexaconazole, triadimenol, propiconazole, epoxiconazole, fenbuconazole, tetraconazole, bromuconazole, diniconazole, difenoconazole and tebuconazole.

Description

FUNGICIDAL COMPOSITIONS The present invention relates to fungicidal compositions, more specifically to fungicidal compositions containing a first fungicidally active compound and a second fungicidally active compound, and a method of combatting phytopathogenic fungi.

All of the fungicidally active compounds contemplated by this application are known as sterol biosynthesis inhibitors belonging to the triazole family. They have, in the past, been used separately to combat various types of pathogenic fungi. It has now been found that certain combinations of such triazoles result in fungicidal compositions that demonstrate unexpected synergistic fungicidal activity.

The fungicidal composition of this invention, accordingly, is characterized in that it comprises a first fungicidally active compound selected from the group consisting of (a) cyproconazole and flutriafol, hereinafter component (a); and a second fungicidally active compound selected from the group consisting of (b) sterol biosynthesis inhibitors belonging to the triazole family, hereinafter component (b); wherein components (a) and (b) are different from each other and are present in the composition in amounts producing a synergistic fungicidal effect.

The triazole family of fungicides includes flutriafol, flusilazole, hexaconazole, triadimenol, propiconazole, epoxiconazole, fenbuconazole, tetraconazole, bromuconazole, diniconazole, difenoconazole and tebuconazole, each of which are known and commercially available.

A preferred combination according to the invention is that of cyproconazole with a triazole selected from the aforementioned group b). Particularly preferred combinations are those of cyproconazole with any one selected from the group comprising flutriafol, flusilazole, propiconazole, difenoconazole and fenbuconazole. Another group of preferred combinations comprises flutriafol as component (a) and any one of the components (b) selected from the group comprising tetraconazole, tebuconazole and epoxiconazole. However, the most preferred combination is that of cyproconazole and flutriafol.

Fungicidal compositions according to the invention are effective in combatting a variety of fungi including Erysiphe graminis f. sp.

hordei in barley, Erysiphe graminis f. sp. tritici in wheat, Cochliobolus sativus in barley, Septoria nodorum and Septoria tritici in wheat and barley, Puccinia striiformis and Puccinia recondita in wheat, Drechslera teres in barley, and Drechstera tritici-repentis in wheat.

The weight ratio of the first fungicidally active compound to the second fungicidally active compound in fungicidal compositions according to the invention will depend on various factors such as the particular active ingredient, the mode of application, the pathogenic fungi to be combatted, the crop, the application time, etc. In general, good results are obtained with compositions containing a weight ratio of component (a) to component (b) ranging from 1:1 to 1:4. More preferably, the weight ratio of component (a) to component (b) will range from 1:1 to 1:2.

Suitable fungicidally effective aggregate amounts of the first and second fungicidally active compounds lie in the range of from 50 to 100 g/ha of crop locus. In general, satisfactory results will be obtained when employing from 20 to 100 g/ha of the first fungicidally active compound, more particularly 60 to 80 g/ha, and from 40 to 150 g/ha of the second fungicidally active compound.

Though formulating the components of the combination into a single combined form and to utilize spray liquors prepared therefrom on cultivated areas is the preferred embodiment of present invention, it is also possible to apply the components separately or in form of a tank-mixture spray being prepared from separate concentrated forms of these components shortly before spraying.

The application rate may also be expressed in terms of concentrations.

Spray liquors suitable for use in, for example, grapevines or cereals comprise from 50 to 250 g per hectoliter. The spray treatment involves usually foliar application until run-off. This corresponds in general with a spray volume of from 600 to 1000 liters per hectare of crop locus, depending upon type of crop, field conditions, etc.

Compositions according to the invention may be formulated in any conventional form, for example in the form of a twin pack, or of an emulsifiable concentrate, a soluble concentrate, a wettable powder or water dispersible granule. Such compostions can be formulated using adjuvents and formulation techniques that are known in the art for individually formulating the fungicidally active compounds, for example by mixing the first fungicidally active compound with the second fungicidally active compound together with diluents and optionally other formulating ingredients such as surfactants.

The term diluent as used herein means any liquid or solid agriculturally acceptable material - including carriers which may be added to the fungicidally active compounds to bring them in a suitable application or commercial form. Diluents include talc, kaolin, diatomaceous earth, mineral oil and water.

Formulations to be applied in spraying forms such as water dispersible concentrates or wettable powders may contain surfactants such as wetting and dispersing agents, e.g. the condensation product of formaldehyde with naphthalene sulponate, an alkylarylsulphonate, a lignin sulphonate, a fatty sulphate, an ethoxylated alkylphenol and an ethoxylated fatty alcohol.

In general, the formulation include from 0.01 to 90% by weight of fungicidally active compounds, from 0 to 20% agriculturally acceptable surfactant and 10 to 99.99D solid or liquid diluent. The formulations may additionally contain additives such as pigments, thickeners and the like.

The formulations listed below are representative of suitable formulations for use in the invention, and are admixed and agitated in accordance with conventional methods to obtain fungicidal compositions.

Formulation 1 200 g/l cyproconazole 200 g/l flutriafol 55 g/l nonionic polymeric emulsifier blend (polyalkylene glycol ether/polyoxyethylene alkylaryl ether blend) 66 g/l antifreeze (1,2-propanediol) 3 g/l thickening agent (xanthane gum) 1 g/l bactericide (1,2-benzisothiazolin-3-one sodium salt) 4 g/l antifoam agent (polysiloxane) balance water Formulation 2 25 g/l cyproconazole 50 g/l flusilazole 57 g/l emulsifier (nonylphenol-polyoxyethylene-phosphates) 96 g/l solvent (N-methyl-2-pyrrolidone) balance solvent (polyethyleneglycole) Formulation 3 (emulsifiable concentrate) 25 g/l cyproconazole 100 g/l triadimenol 74 g/l emulsifier (nonylphenyl-polyoxyethylene-phosphates) 92 g/l emulsifier (alkyl-polyoxyethylene-phosphates) 46 g/l solvent (hexanol) 101 g/l solvent (N-methyl-2-pyrrolidone) balance solvent (mixture of Cg to C11 fatty alcohols) Formulation 4 (wettable granules) 5 % cyproconazole 10 % propiconazole 15 X dispersing agent (sodium lignin sulfonate) 70 % carrier (calcium magnesium carbonate) The combinations of active ingredients as indicated above are effective in combatting various type of fungi including the following fungi and the symptoms to which they lead.

Fungicidal testing The efficiency of the mixture according to the invention in controlling various pathogenic fungi is demonstrated using the following procedure.

In vivo tests: Erysiphe graminis in wheat or barley Wheat or barley is cultivated for 8-10 days in a mixture of peat and sand in plastic pots of 6 cm diameter. The plants are spray treated with aqueous spray liquors containing a compound A, a compound B or mixtures thereof (hereinafter a.i.) in various concentrations. The treatment comprises foliar spraying to near runoff. After drying (24h), the plants are inoculated in a settling tower with dry spores of Erysiphe graminis and are then incubated for 7 days in a growth chamber at 60-80% relative humidity, 16 hours daylight and 200C. The efficacy of the a.i. is determined by comparing the degree of fungal attack on the treated plants with that on untreated, similarly inoculated and incubated check plants. Each a.i. is tested in 4 to 5 concentrations.This allows for the determination of the experimental EC 90 value (EC 90 exp.), i.e. the concentration of each a.i.

providing 90% disease control.

Analogous tests are run with Septoria nodorum on wheat. In these tests, the inoculation of the plants is done by spray application of a spore suspension containing 1 x 105 spores/ml.

Activity of the a.i. against Puccinia striiformis or Puccinia recondita on wheat is tested analogously, but on detached leaves.

Wheat plants are cultivated and spray treated in accordance with the above mentioned methods. After drying, the primary leaves of the plants are detached, inoculated in a spore-settling tower and incubated on water agar for 20 days at 100C.

In vitro tests: Activity of the a.i. against Septoria tritici, Septoria nodorum, Drechslera teres and Drechslera tritici-repentis is tested in vitro.

Potato dextrose agar medium (PDA) is prepared and cooled to 550C.

Quantities of fungicide solutions in water are added to give the following concentrations in the agar medium: 0.01, 0.1, 1, 10 and 100 ppm a.i. Agar plugs are cut from the edge of growing colonies of the fungi to be tested using a cork borer. These plugs are placed on the fungicide-amended agar media. The radial mycelial growth is measured after incubation for 7 days at 200C in the dark and compared to the growth on PDA without fungicides. The EC 90 exp. value is calculated.

Calculation of synergistic effects: The experimental result (EC 90 exp.) for a given weight ratio of Compound A : Compound B is compared with the corresponding EC 90 theor. value, i.e. the concentration of that particular mixture allowing 90% disease control calculated according to Wadley: a+b EC (A+B) 90 theor. = a + b EC(A)90 exp. EC(B)90 exp.

wherein a and b are the ratios of Compund A and Compound B in the mixture and the indexes (A) (B) and (A+B) refer to the EC 90 values of Compound A, Compound B and the a:b mixture of Compound A and Compound B, respectively. In case of synergism EC(A+B)90 theor. is greater than EC(A+B)90 exp., or EC(A+B)90 theor.

Synergy-factor (SF) = ~~~~~~~~~~~~~~~ > 1.

EC(A+C)90 exp.

According to these tests, the mixtures of the invention show an activity which is markedly superior to the sum of the activity of each of the active agents when taken individually.

Claims (11)

WHAT IS CLAIMED IS:

1. A fungicidal composition characterized in that it comprises a first fungicidally active compound selected from the group consisting of (a) cyproconazole and flutriafol, hereinafter component (a); and a second fungicidally active compound selected from the group consisting of (b) sterol biosynthesis inhibitors belonging to the triazole family, hereinafter component (b); wherein components (a) and (b) are different from each other and are present in the composition in amounts producing a synergistic fungicidal effect.

2. A fungicidal composition according to claim 1 wherein component (b) is selected from the group consisting of flutriafol, flusilazole, hexaconazole, triadimenol, propiconazole, epoxiconazole, fenbuconazole, tetraconazole, bromuconazole, diniconazole, difenoconazole and tebuconazole.

3. A fungicidal composition according to claims 1 or 2 wherein component (a) is cyproconazole.

4. A fungicidal composition according to claim 3 wherein component (b) is flutriafol.

5. A fungicidal composition according to claim 3 wherein component (b) is selected from the group comprising flutriafol, flusilazole, propiconazole, difenoconazole and fenbuconazole.

6. A fungicidal composition according to claims 1 or 2 wherein component (a) is flutriafol.

7. A fungicidal composition according to claim 6 wherein component (b) is selected from the group comprising tetraconazole, tebuconazole and epoxiconazole.

8. A fungicidal composition according to claim 1 comprising a combination of cyproconazole and flutriafol.

9. A fungicidal composition according to any one of claims 1 to 8 wherein the weight ratio of component (a) to component (b) ranges from 1:1 to 1:4.

10. A fungicidal composition according to claim 9 wherein the weight ratio of component (a) to component (b) ranges from 1:1 to 1:2.

11. A method of combating phytopathogenic fungi which comprises applying an fungicidally effective amount of a composition according to Claim 1 to crop plants or the locus thereof being infested with said phytopathogenic fungi.