WO2011030094A2

WO2011030094A2 - Fungicidal mixtures

Info

Publication number: WO2011030094A2
Application number: PCT/GB2010/001685
Authority: WO
Inventors: David Beattie; Alexander Cornish; Andrew John Corran; Patrick Joseph Mulqueen; Andrew John Leadbeater; Stephen John Maund; Leslie Francis May; Naomi Pain; David Philip John Pearson; David Stock; Gina Mercia Swart; Martin Werle; Jayne Ann Wright; Richard Brian Perry
Original assignee: Syngenta Participations AG; Syngenta Ltd
Current assignee: Syngenta Participations AG; Syngenta Ltd
Priority date: 2009-09-09
Filing date: 2010-09-06
Publication date: 2011-03-17
Anticipated expiration: 2012-03-09
Also published as: WO2011030094A3

Abstract

A composition comprising a polymeric biguanide (PB) or salt thereof and a fungicide selected from the group consisting of a phenyl amide (acylalanine) fungicide, a strobilurin fungicide, Mandipropamid, a triazole fungicide, bion, cyprondinil and a carboxamide (SDHI inhibitor) fungicide.

Description

FUNGICIDAL MIXTURES

The present invention relates to agrochemical compositions comprising fungicides. The invention also relates to the preparation of the compositions, and the use of the compositions in agriculture or horticulture for preventing infestation of plants, harvested food crops, seeds or non living materials, by phytopathogenic micro-organisms, particularly fungi.

It has now been surprisingly discovered that a combination of a polymeric biguanide (PB) and or salts thereof and specific fungicides provide a fungicidal effect significantly greater than that expected merely from the combination of the individual components.

According to the present invention there is provided a composition comprising a PB or salt thereof and a fungicide selected from the group consisting of a phenyl amide (acylalanine) fungicide, a strobilurin fungicide, Mandipropamid, a triazole fungicide, bion, cyprodinil and a carboxamide (SDHI inhibitor) fungicide.

By PB is meant a polymeric biguanide or a salt thereof, which is in its free base form has a recurring polymer unit represented by the formula:

— X— NH-C-NH-C— NH-Y-NH-C— NH-C-NH

NH NH NH NH

wherein X and Y, which may be the same or different, represent bridging groups - (CH₂)_n and (CH₂)m respectively, n and m having values from 3 to 12, or X and Y represent other bridging groups in which, taken together, the total number of carbon atoms directly interposed (as defined herein) between the pairs of nitrogen atoms linked by X and Y is from 10 to 16, and wherein the polymeric biguanide comprises a mixture of polymers in which the individual polymer chains are of different lengths, the number of individual polymer units:

— X— NH— C— NH— C-NH

NH NH

and

NH— C— NH— C— NH

I I I I NH NH taken together in any polymer chain being from 3 to 80, and wherein the groups terminating the polymer chains, which groups may be the same or different, are selected from

— NH₂— NH— C— NHCN and— NH— C— NH— C— NR NR

II II II

NH NH NH

wherein R, is hydrogen or a substituted or unsubstituted aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radical containing from 1 to 18 carbon atoms and R₂ is a substituted or unsubstituted aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radical containing from 1 to 18 carbon atoms.

In particular the PB may be a polymeric biguanide or a salt thereof which, in its free base form, has a recurring polymer unit represented by the formula:

X— NH— C— NH— C— NH— Y— NH— C— NH— C— NH

II II II II

NH NH NH NH

wherein X and Y are hexamethylene, hereinafter "PHMB".

The present compositions can be used in the agricultural sector and related fields of use e.g. as a combined active ingredient for controlling plant pests or on non-living materials for control of spoilage microorganisms or organisms potentially harmful to man. The compositions are distinguished by excellent activity at low rates of application, by being well tolerated by plants and by being environmentally safe. They may exhibit useful curative, preventive and systemic properties and may be used for protecting numerous cultivated plants. The compositions can be used to inhibit or destroy the pests that occur on plants or parts of plants (fruit, blossoms, leaves, stems, tubers, roots) of different crops of useful plants, while at the same time protecting also those parts of the plants that grow later e.g. from phytopathogenic microorganisms.

In particular the phenylamide fungicide is preferably Metalaxyl, Benalaxyl or

Mefenoxam. Mefenoxam is also known as Metalaxyl M and is a Metalaxyl preparation enriched in the R enantiomer, which inter alia exhibits improved soil degradation characteristics in comparison with the racemate. Metalaxyl is known from the fourteenth edition of the Pesticide Manual, under entry 535, Metalaxyl M (Mefenoxam) from entry 536 and Benalaxyl from entry 56. The PHMB is preferably in the form of a salt, in particular the salt of an organic acid. Whilst many salts are contemplated, in particular the benzoate, oleate and citrate salts are preferred. The PHMB and fungicide present in the composition preferably exhibit a synergistic effect with respect to each other - meaning that for a given degree of fungal control less active ingredient needs to be employed - which provides the farmer with advantages in terms of lower costs and ease of application but is also less of an environmental burden. The present inventive compositions may also contain other active ingredients, for example, other fungicides, insecticides, herbicides, plant growth regulators, nematicides and/or acaricides, as are all well know to the skilled man.

The present invention also includes a method of controlling plant pathogens comprising application to a plant or a locus of the pathogen the present inventive compositions comprising a PB and selected fungicide.

The invention also includes the use of a PB; particularly a PHMB or a salt thereof, or a fungicide selected from the group consisting of a phenyl amide (acylalanine) fungicide, a strobilurin fungicide, Mandipropamid, a triazole fungicide, bion, cyprodinil and a carboxamide (SDHI inhibitor) fungicide in the preparation of the present inventive compositions.

In a preferred embodiment the PB is a PHMB and/or the fungicide is a phenylamide (acylalanine) fungicide.

It is possible to use the present inventive compositions as dressing agents for the treatment of plant propagation material, e.g., seed, such as fruits, tubers or grains, or plant cuttings (for example rice), for the protection against fungal infections as well as against phytopathogenic fungi occurring in the soil. The propagation material can be treated with a composition before planting: seed, for example, can be dressed before being sown. The compositions according to the invention can also be applied to grains (coating), either by impregnating the seeds in a liquid formulation or by coating them with a solid formulation. The compositions can also be applied to the planting site when the propagation material is being planted, for example, to the seed furrow during sowing. The invention relates also to such methods of treating plant propagation material and to the plant propagation material so treated.

Furthermore the compositions according to present invention can be used for controlling fungi in related areas, for example in the protection of technical materials, including wood and wood related technical products, in food storage, and in hygiene

management. In addition, the invention could be used to protect non-living materials from fungal attack, e.g. timber, wall boards and paint. Within the scope of present invention, target crops and/or useful plants to be protected by the present inventive compositions typically comprise the following species of plants: cereal (wheat, barley, rye, oat, rice, maize, sorghum and related species); beet (sugar beet and fodder beet); pomes, drupes and soft fruit (apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries and blackberries); leguminous plants (beans, lentils, peas, soybeans); oil plants (rape, mustard, poppy, olives, sunflowers, coconut, castor oil plants, cocoa beans, groundnuts); cucumber plants (pumpkins, cucumbers, melons); fibre plants (cotton, flax, hemp, jute); citrus fruit (oranges, lemons, grapefruit, mandarins); vegetables (spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, paprika); lauraceae (avocado, cinnamomum, camphor) or plants such as tobacco, nuts, coffee, eggplants, sugar cane, tea, pepper, vines, hops, bananas and natural rubber plants, as well as turf and ornamentals.

The useful plants and / or target crops in accordance with the invention include conventional as well as genetically enhanced (for example herbicide and/or insecticide resistant) or engineered varieties.

The term "locus" of a plant as used herein is intended to embrace the place at which the plants are growing, where the plant propagation materials of the plants are sown or where the plant propagation materials of the plants will be placed into the soil. An example for such a locus is a field, in which crop plants are growing.

The term "plant propagation material" is understood to denote generative parts of the plant, such as seeds, which can be used for the multiplication of the latter, and vegetative material, such as cuttings or tubers, for example potatoes. There may be mentioned for example seeds (in the strict sense), roots, fruits, tubers, bulbs, rhizomes and parts of plants. Germinated plants and young plants which are to be transplanted after germination or after emergence from the soil, may also be mentioned. These young plants may be protected before transplantation by a total or partial treatment by immersion. Preferably "plant propagation material" is understood to denote seeds. The compositions of the invention may be used in unmodified form or, preferably, together with the adjuvants conventionally employed in the art of formulation. To this end they may be conveniently formulated in known manner as emulsifiable

concentrates, coatable pastes, directly sprayable or dilutable solutions or suspensions, dilute emulsions, wettable powders, soluble powders, dusts, granulates, and also encapsulations e.g. in polymeric substances. As with the type 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. The compositions may also contain further adjuvants such as stabilizers, antifoams, viscosity regulators, binders or tackifiers as well as fertilizers, micronutrient donors or other formulations for obtaining special effects.

Suitable carriers and adjuvants, e.g. for agricultural use, can be solid or liquid and are substances useful in formulation technology, e.g. natural or regenerated mineral substances, solvents, dispersants, wetting agents, tackifiers, thickeners, binders or fertilizers. Such carriers are for example described in WO 97/33890.

The compositions can be applied to the crop area or plant to be treated, simultaneously or in succession with further compounds. These further compounds can be e.g.

fertilizers or micronutrient donors or other preparations, which influence the growth of plants. They can also be selective herbicides or non-selective herbicides as well as insecticides, fungicides, bactericides, nematicides, molluscicides or mixtures of several of these preparations, if desired together with further carriers, surfactants or application promoting adjuvants customarily employed in the art of formulation. Said fungicidal compositions for controlling or protecting against phytopathogenic microorganisms, and at least one of the above-mentioned adjuvants, can be mixed with other fungicides. Mixing components which are particularly preferred are: azoles, pyrimidinyl carbinoles, morpholies, anilinopyrimidines, pyrroles, phenylamides, benzimidazoles, dicarboximides, carboamides, strobilurines, dithiocarbamates, n- halomethylthiotetrahydrophthalimides, copper-compounds, nitrophenol-derivatives, organo-phosphorus-derivates, and triazolopyrimidine derivatives. Within the context of the present invention, controlling or preventing means reducing infestation by phytopathogenic or spoilage microorganisms or organisms potentially harmful to man, especially fungal organisms, to such a level that an improvement is demonstrated.

A preferred method of controlling or preventing an infestation of crop plants by phytopathogenic microorganisms, especially fungal organisms, which comprises the application of the present inventive compositions, is foliar application. The frequency of application and the rate of application will depend on the risk of infestation by the corresponding pathogen. However, the compositions can also penetrate the plant through the roots via the soil (systemic action) by drenching the locus of the plant with a liquid formu}ation, or by applying the compounds in solid form to the soil, e.g. in granular form (soil application). In crops of water rice such granulates can be applied to the flooded rice field. The compositions may also be applied to seeds (coating) by impregnating the seeds or tubers either with a liquid formulation of the fungicide or coating them with a solid formulation.

The agrochemical formulations and/or compositions will usually contain from 0.1 to 99% by weight, preferably from 0.1 to 95% by weight, of the fungicidal constituents, 99.9 to 1 % by weight, preferably 99.8 to 5% by weight, of a solid or liquid adjuvant, and from 0 to 25% by weight, preferably from 0.1 to 25% by weight, of a surfactant.

Advantageous rates of application may be from 5g to 2kg of active ingredient (a.i.) per hectare (ha), preferably from 10g to 1 kg a.i. /ha, most preferably from 20g to

600g a.i./ha. When used as seed drenching agent, convenient dosages are from 10mg to 1 g of active substance per kg of seeds.

Whereas it is preferred to formulate commercial products as concentrates, the end user will normally use dilute formulations.

The invention is further apparent from the following non-limiting examples. Examples:

Experiments were carried out to demonstrate synergistic activity between PHMB and other fungicidal/bactericidal compounds.

Materials and Methods:

Plant growth and selection: 2 week old tomato (var. Outdoor Girl) plants were grown in 1.5 inch diameter mini pots in John Innes potting compost No. 3 (50:50 peat:No.3), in a controlled environment room (day time temperature 21°C 60% Relative Humidity; night time temperature 17°C 95% Relative Humidity; 16 hours day length; l OOumol). Plants of similar size, with the first true leaves nearly fully expanded were selected for use in each test (approx 2 weeks post sowing).

Pathogen production: Sporangia of Phytophthora infestans were produced on tomato leaves. Tomato plants var 'Ailsa Craig' were grown in 5 inch diameter pots and the lower leaves from 6 week old plants were utilised. Leaves were laid in plastic seed trays, abaxial surface upwards, on damp blotting paper, and sprayed with a sporangial suspension at 750 sporangia per ml, using a Devilbiss hand held spray gun at 10psi until fine droplets formed. The trays were placed into thick gauge clear plastic bags and sealed. Trays were incubated in a controlled environment room (day time temperature 21 °C 60% Relative Humidity; night time temperature 17°C 95% Relative Humidity; 16 hours day length; l OOpmol) and covered with perforated thin black plastic until sporangiophores were observed (typically after 4d), after which they are transferred to a 4°C fridge.

Test design: Each synergy experiment consisted of the following treatments: untreated inoculated controls (sprayed with de-ionised water alone); five rates each of PHMB salt- only and partner compound-only treatments (solo treatments); and 19 treatments comprising mixtures of PHMB and the partner compound at these rates in different combinations. The combinations were created to give five different ratios of PHMB-salt to partner compound, applied at different rates (Fig. 1 ). 7 replicate plants were used for each treatment (28 for untreated, inoculated controls). Chemical preparation and spray: Compounds were solubilised in acetone or methanol/acetone to give a l OOOppm stock solution, and treatment solutions (solo and mixtures) were produced from these stock solutions diluted in de-ionised water to give the desired rates. In each case, the rates of the solo treatments were selected as the rates required to give an anticipated level of 30-60% disease control in the single- compound controls, compared to untreated plants.

The compounds and mixtures were applied to the first true leaves of the plants to maximum retention, using an air-pressure powered hand held Devilbiss spray-gun, set to 10psi. After application, the plants were left to dry, randomised, and then incubated in a controlled environment room (day time temperature 21°C 60% Relative Humidity; night time temperature 17°C 95% Relative Humidity; 16 hours day length; l OOpmol) at 17°C overnight. One day after chemical application, the plants were inoculated with sporangia of Phytophthora infestans (isolate number K3067), in de-ionised water at a concentration of 500 sporangia/ml. As with the chemical application, inoculum was applied to maximum retention using a spray-gun at 10psi. Plants were placed overnight in darkness at 100% relative humidity and 22°C to encourage spore germination, and after 24 hours were returned to the controlled environment room (day time temperature 21°C 60% Relative Humidity; night time temperature 17°C 95% Relative Humidity; 16 hours day length; 100μηηοΙ) for a further four days until assessment.

The percentage disease coverage (percentage of the leaf area covered by disease lesions) was assessed as an average for both of the first two true leaves of each plant, 4-5 days after inoculation. Two independent assessments were made, and mean values for the two assessments were used to generate the values for synergy calculations. The percentage disease coverage was converted to a % disease coverage relative to control (PRCO) by comparing to the disease levels obtained to the untreated, inoculated control plants. Synergistic action was determined by use of the Colby formula

+ P₂ - ([Pi x Ρ_∑] / 100), Pi and P₂ being the scores for the compound-only treatments at the appropriate rates). The use of the Colby formula to calculate expected disease control is justified in this case because of the clear difference in mode of action between the two compounds (mefenoxam is thought to inhibit ribosomal RNA in the nucleus, PHMB affects the integrity of the cell membrane). This gives an expected value for disease control from each mixture treatment, based on the scores for the equivalent rates in the single- compound controls. Synergy is considered to have occurred where the observed score for a mixture treatment is clearly greater than the expected score generated by the formula.

Results:

PHMB-Benzoate and mefenoxam: Comparison of observed and expected (as calculated using the Colby formula) levels of disease control demonstrate that synergistic action has occurred between PHMB-Benzoate and mefenoxam. In table 1 , synergy was apparent in every mixture rate involving Mefenoxam at 0.44ppm or less. It is likely that synergy was obscured at higher rates because of the greater than anticipated disease control on the Mefenoxam-only control treatments at 1.0 and 0.67ppm.

Table 1 : Summary of results for the PHMB Benzoate-Mefenoxam synergy test.

¹Observed scores- percent disease control relative to untreated controls, observed in the mixture treatments. ²Expected scores- Colby formula result for single-compound controls at the rates used in the mixture treatment, difference in percentage disease control between observed and expected results for each treatment.

PHMB Citrate and Mefenoxam: Synergistic action was also observed in testing with PHMB-Citrate and mefenoxam (Table 2). In this case, the level of disease control observed in the test was lower throughout, resulting in lower 'expected' scores via the Colby formula. This allowed clear synergy to be observed across all mixture rates and ratios.

Table 2: Summary of results for the PH B Citrate- efenoxam synergy test.

Further experiments were carried out to demonstrate synergistic activity between the free base of PHMB and Mefenoxam, in support of previous work which showed synergy between Mefenoxam and two different salts of PHMB, exemplified by control of

Phytophthora infestans.

Materials and Methods:

Plant growth and selection: 2 week old tomato (var. Outdoor Girl) plants were grown as indicated above. Pathogen production: Sporangia of Phytophthora infestans were produced as indicated above.

Test design: Each synergy experiment consisted of the following treatments: untreated inoculated controls; five rates each of PHMB-only and mefenoxam-only treatments (solo treatments); and 19 treatments comprising mixtures of PHMB and mefenoxam at these rates in different combinations. The combinations were created to give five different ratios of PHMB to partner compound, applied at different rates (Fig. 2). 7 replicate plants were used for each treatment (28 for untreated, inoculated controls). Chemical preparation and spray: PHMB free base was dissolved in methanol and mefenoxam in acetone to give l OOOppm stock solutions, and treatment solutions (solo and mixtures) were produced from these stock solutions diluted in de-ionised water to give the desired rates (the pH of the water was checked before use to ensure that it was not acidic, and that the PHMB free base would not be forming salts within the treatment formulation). In each case, the rates of the solo treatments were selected as the rates required to produce an anticipated level of disease control spanning 60-30%, based on prior experiments and siting tests.

The compounds and mixtures were applied to the first true leaves of the plants to maximum retention, using an air-pressure powered hand held Devilbiss spray-gun, set to 10psi. After application, the plants were left to dry, randomised, and then incubated in the dark in a controlled environment room at 17°C overnight. One day after chemical application, the plants were inoculated with sporangia of Phytophthora infestans (isolate number K3067), in de-ionised water at a concentration of 500 sporangia/ml. As with the chemical application, inoculum was applied to maximum retention using a spray-gun at 10psi. Plants were placed overnight in darkness at 100% relative humidity and 22°C to encourage spore germination, and after 24 hours were returned to the a 21 °C controlled environment room for a further four days until assessment.

The percentage disease coverage (percentage of the leaf area covered by disease lesions) was assessed as an average for both of the first two true leaves of each plant, 5 days after inoculation. Two independent assessments were made. The percentage disease coverage was converted to percent disease coverage relative to control (PRCO) by comparing to the disease levels obtained to the untreated, inoculated control plants.

As above, synergistic action was determined by use of the Colby formula.

Results: The level of disease control throughout the mixture treatments was

consistently higher than would be expected from the independent action of the two test compounds (Table 3). Although the difference between observed and expected values is lower in treatments with high rates of mefenoxam, this is most likely due to the high levels of disease control in the independent treatments raising the expected value to a point where synergy is difficult to observe.

Table 3: Summary of results for the PH B free base-mefenoxam synergy test.

Observed scores- percent disease control relative to untreated controls, observed in the mixture treatments. ²Expected scores- Colby formula result for single-compound controls at the rates used in the mixture treatment^, difference in percentage disease control between observed and expected results for each treatment.

Discussion:

The presence of better-than-expected disease control in the salts of PHMB and the free base when combined with mefenoxam, occurring at several different rates and across five ratios, leads us to conclude that synergism is detected between such mixtures, exemplified by their effect on Phytophthora infestans.

Claims

A composition comprising a polymeric biguanide (PB) or a salt thereof and a fungicide selected from the group consisting of a phenyl amide (acylalanine) fungicide, a strobilurin fungicide, Mandipropamid, a triazole fungicide, bion, cyprodinil and a carboxamide (SDHI inhibitor) fungicide.

A composition according to claim 1 , wherein the PB is a poly hexamethylene biguanide (PHMB).

A composition according to either of claims 1 or 2, wherein the fungicide is a phenyl amide (acylalanine) fungicide.

A composition according to any one of claims 1 to 3, wherein the fungicide is Metalaxyl or Mefenoxam.

A composition according to any one of claims 2 to 4, wherein the PHMB is in the form of a salt.

A composition according to the preceding claim, wherein the salt is an organic acid salt.

A composition according to the preceding claim, wherein the salt is a benzoate, oleate or citrate salt.

A composition according to any preceding claim, wherein the PB and fungicide are present in the composition in an amount capable of exhibiting a synergistic effect.

A composition according to any preceding claim, further comprising at least one further fungicide, insecticide, herbicide, plant growth regulator, nematicide or acaricide.

A method of controlling a plant pathogen comprising application to a plant or a locus of the pathogen the composition of any one of claims 1 to 9.

1 1. Use of the composition according to any one of claims 1 to 9 in the preparation of a composition to control plant pathogens.

12. Use of a PB or salt/or a fungicide selected from the group consisting of a phenyl amide (acylalanine) fungicide, a strobilurin fungicide, Mandipropamid, a triazole fungicide, bion, cyprodinil and a carboxamide (SDHI inhibitor) fungicide in the preparation of the composition of any one of claims 1 to 9. 3. A method of making the composition of any one of claims 1 to 9, comprising adding (i) a PB to (ii) a fungicide selected from the group consisting of a phenyl amide (acylalanine) fungicide, a strobilurin fungicide, Mandipropamid, a triazole fungicide, bion, cyprodinil and a carboxamide (SDHI inhibitor) fungicide or vice versa.