RU2548191C1 - Composite agent of fungicidal action for protection of plants against pathogens, including those resistant to commercial fungicides - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: composite agent of fungicidal action comprises the active ingredient, which is used as a complex comprising strobilurins or triazoles fungicide in the concentration of 0.01-3000 ppm and a chemosensitiser in the concentration of 1-1000 ppm, which is used as 2,3-dioxybenzaldehyde-(2,3-DOBA), 4-oxybenzaldehyde (4-OBA), thymol or culture liquid filtrate (CLF) of the strain of fungus Fusarium sambucinum FS-94. The ratio of the fungicide and the chemosensitiser is 1:1-10:1.

EFFECT: invention improves the fungicidal activity and the lifetime of the fungicide, provides overcoming of resistance to fungicides in phytopathogens.

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Description

The invention relates to crop protection products, in particular to fungicidal compositions.

The resistance of phytopathogenic fungi to agricultural fungicides is an important problem for agriculture, ensuring the quality and safety of crop products, as well as for public health. Attempts to solve this problem by using increased doses of commercial antifungal agents often lead to negative environmental side effects due to the toxicity of these agents. This dictates the urgent need to create the latest safe fungicides, or methods that will improve the effectiveness of existing plant protection products.

It is known to use fungicidal compositions containing mixtures based on a salt of copper and phosphorous acid, also called phosphite or phosphonate, with another metal salt of phosphorous acid and one or more fungicidal compounds (RF Patent No. 2403717).

A disadvantage of the known solution is the lack of fungicidal activity of the composition, a short period of protective action.

A fungicidal mixture is known which contains prochloraz or its complex salt, tebuconazole or ciproconazole and thiabendazole. This mixture is synergistic. The fungicidal agent may be presented in the form of a suspension or emulsion. The mixture is used to combat phytopathogenic fungi on plants and seeds of agricultural crops (RF Patent No. 2460293).

The disadvantages of this drug include the need to use the mixture in sufficiently high doses, as well as high toxicity to aquatic organisms.

A synergistic fungicidal composition is known including 2,6-dichloro-N - {[3-chloro-5- (trifluoromethyl) -2-pyridinyl] methyl} benzamide and mancozeb, used in a weight ratio of from 1/100 to 5/1 (Patent RF №2292137).

To ensure long-term and effective protection of crops from diseases, a large number of treatments with this drug are required due to the short protective period of action. In addition, high doses of its use are required.

Known antifungal composition for treating plants, fruits, seeds and parts thereof, containing didecylammonium chloride and a post-harvest antifungal component selected from the group consisting of imazalil, boscalide, fengexamide, pyrimethanil, thiofanate methyl and pyraclostrobin, in appropriate proportions that provide a synergistic effect against (RF patent No. 2361400).

The disadvantage of this solution is the use of the post-harvest component, which significantly reduces the scope of the fungicide and increases the environmental hazard.

Synergistic fungicidal combinations of biologically active substances are known which contain one carboxamide and a biologically active substance selected from strobilurins, triazoles, sulfenamide, valinamides, carboxamides, dithiocarbamates, acylalanines, anilino-pyrimidines, benzimidazole, carbamates, dicarboximide phosphide triazides from compounds: chlorothalonil, spiroxamine, phenamidone, pencicuron, triazolopyrimidines (RF Patent No. 2381650).

The disadvantages of this drug are the need for high doses, a sufficiently high toxicity and environmental hazard of some of the compounds that make up the composition.

This invention is a new fungicidal composition that increases the effectiveness of existing commercial fungicides and is able to enhance the effect of newly created antifungal agents. The invention uses safe natural substances in combination with known antifungal synthetic compounds, which provides a significant increase in the fungicidal action of the latter against phytopathogenic fungi. This process, called "chemosensitization", is that safe natural compounds (chemosensitizing agents) weaken the ability of pathogenic fungi to protect themselves from the effects of chemical compounds exhibiting fungicidal properties.

The technical result of this invention is the increase of fungicidal activity and the duration of the fungicide, as well as overcoming resistance to fungicides in phytopathogens.

The technical result is achieved in that the composite preparation of fungicidal action contains an active substance, which is used as a complex comprising a fungicide - strobilurins or triazoles in a concentration of 0.01 ... 3000 ppm and a chemosensitizer in a concentration of 1 ... 1000 ppm, taken in a ratio of 1: 1 ... 10: 1, while the chemosensitizer is selected from 2,3-dioxibenzaldehyde, 4-hydroxybenzaldehyde, a solution of thymol in dimethyl sulfoxide or a filtrate of the culture fluid of the strain of the fungus Fusarium sambucinum FS-94.

All chemosensitizers, except for water-insoluble thymol, are used in the form of aqueous solutions, and thymol is dissolved in 0.5 ... 1% aqueous dimethyl sulfoxide.

The use of a number of fungicides, such as triazoles and strobilurins, widely used in agricultural practice, together with these substances provides a synergistic effect that qualitatively enhances fungicidal properties against phytopathogenic fungi, which cause significant harm to agriculture.

The ability to enhance the fungicidal effect is shown for combinations of thymol (2-isopropyl-5-methylphenol) with azoxystrobin (chemical class: strobilurins) in relation to Phoma glomerata, Bipolaris sorokiniana, Alternaria sp. and Stagonospora nodorum with diphenoconazole 3.0 g / L (chemical class: triazoles) against B. sorokiniana and S. nodorum; as well as tebuconazole (chemical group: triazoles) against Alternaria alternata.

Among these plant pathogens, the greatest synergistic effect was revealed for B. sorokiniana in the combination of thymol and azoxystrobin at concentrations of 10 ppm and 100 ppm, respectively. With individual use of thymol at the indicated concentration, there was practically no delay in the growth of the pathogen. However, a mixture of thymol and azoxystrobin inhibited fungal growth significantly more (40.9%) than the fungicide itself (14.8%).

The same mixture of azoxystrobin with thymol inhibited P. glomerata fungus growth by 88.8%, which was twice as high as inhibition of fungal growth with azoxystrobin alone. This inhibition was 27% higher than the arithmetic sum, which could be due to the additive effect of thymol and azoxystrobin, used separately (12.5% and 48.8%, respectively).

Growth Inhibition Alternaria sp. a mixture of thymol and azoxystrobin (36.4%) also exceeded the arithmetic sum of percent inhibition of fungal growth by each of these substances separately (4.5% + 19.3%).

Thymol (10 ppm) also sensitized B. sorokiniana and S. nodorum to diphenoconazole, and A.alternata to tebuconazole. The combination of diphenoconazole with thymol significantly inhibited the growth of B. sorokiniana and S. nodorum colonies compared to the action of each of these substances separately. Adding diphenoconazole to the nutrient medium to a concentration of 1 ppm in the presence of thymol caused the same fungicidal effect as a 10-fold higher concentration (10 ppm) of diphenoconazole alone.

A similar situation was observed in the case of a combination of thymol with tebuconazole. The fungicide tebuconazole at a concentration of 0.5 ppm caused a 29% inhibition of A. alternata colony growth. When thymol was added to tebuconazole at a concentration of 10 ppm, which slightly inhibited the growth of A. alternata, the inhibition of colony growth of this fungus was approximately 50%. To get this effect from one tebuconazole, its concentration had to be twice as high (1.0 ppm).

The ability of another potential chemosensitizer, 4-BOTH, to increase the fungicity of tebuconazole, was studied against A. alternata and the potentially toxinogenic fungus F. culmorum. The combined use of tebuconazole (0.5 ppm) with 4-BOTH, at a concentration of 200 ppm, which slightly inhibited the growth of these fungi, led to a significant increase in fungicidal activity against both F. culmorum and A. alternata. So, one tebuconazole at a concentration of 0.5 ppm inhibited their growth by about 30%, and in the mixture with 4-BOTH its inhibitory effect was almost twice as high.

The chemosensitizing potential of 2,3-DOBA was evaluated by increasing the growth-inhibitory effect of tebuconazole against A. alternata. Both tebuconazole and this benzaldehyde, when used separately, slightly inhibited fungal growth by 10%, respectively, at 0.5 ppm tebuconazole and 2.5% at 1.0 ppm 2,3-DOBA. However, with the combined use of these compounds, inhibition of fungal growth by approximately 25% was observed.

It was found that metabolites from the culture fluid of the F. sambucinum fungus strain FS-94, which is not pathogenic for wheat, possess chemosensitizing activity and increase the sensitivity of S. nodorum fungus (Septoria pathogen) to some thiazoles, in particular tebuconazole and diphenoconazole, prolonging their fungicidal effect.

Filtrates of the culture fluid (PCF) of strain FS-94 were obtained by filtration of the latter after its growth on a medium with molasses, sucrose and ammonia. To study the effect of PCF on the plant pathogen, strain # 13-1 / 3 S. nodorum was grown on potato-glucose medium (KGA) supplemented with PCF and various doses of fungicides. Solutions of PCF, tebuconazole and diphenoconazole were sterilized by filtration through Millipore membranes with a pore diameter of 0.22 microns, followed by addition to Petri dishes with KHA separately and in combination before sowing S. nodorum.

The combined use of tebuconazole and PCF increased the sensitivity of S. nodorum to fungicide. When using PCF at a concentration of 20 μl / ml together with tebuconazole at a concentration of 0.25 ppm, the inhibition of S. nodorum growth after 9 days significantly exceeded the additive effect. Tebuconazole at a concentration of 0.25 ppm inhibited colony growth by 49%. The combination of tebuconazole with PCF led to inhibition of fungal growth by 75%.

Under the influence of PCF, the sensitivity of S. nodorum also increased to diphenoconazole. The use of its combination with PCF (at a concentration of 0.01 ppm of 20 μl / ml, respectively) led to a strong suppression of the growth of colonies of the pathogen on KHA, which significantly exceeded the suppression of growth when individually using both diphenoconazole and PCF. The fungicidal effect of the mixture of diphenoconazole and PCF was 2.5 times higher than the effect of diphenoconazole alone.

Inhibition of growth by a mixture of PCF with tebuconazole enhanced the fungicidal effect of the latter by prolonging this effect and maintaining it at a higher level. As the fungus grew on the KHA, the growth-inhibitory effect of tebuconazole at a concentration of 0.25 ppm gradually weakened, and the reduction in the diameter of the colonies, compared with the control, decreased by 11 days from 72 to 49%. While the growth-inhibitory effect of tebuconazole at the same concentration in the presence of PCF (20 μl / ml), measured by the reduction in colony diameter, remained at 69%.

The growth-inhibitory effect of diphenoconazole against S. nodorum was prolonged with the combined use of this fungicide with PCF. The prolongation of the fungicidal effect under the influence of PCF is a new, previously unknown property of chemosensitizers. In contrast to the antifungal drugs used in medicine, the use of plant protection products is not designed to completely destroy the pathogen (which is unattainable in natural conditions), but to their ability to delay the onset of the disease as far as possible and slow down its development. The combined use of PCF as a sensitizing agent with agricultural fungicides significantly delays the development of diseases, in particular septoria on wheat.

The sensitizing effect of thymol, which was previously selected in vitro as an effective chemosensitizer of F. culmorum and B. sorokiniana to diphenoconazole, was studied in vegetative experiments on wheat and barley plants.

Phytopathological examination of seedlings grown from seeds treated with a mixture of diphenoconazole with thymol showed that their combined use for seed treatment led to a significantly stronger suppression of the disease on plants compared to its suppression on seedlings grown from seeds treated with only diphenoconazole. The prevalence of B. sorokiniana and the degree of development of the disease on barley plants after combined use of seed fungicide and thymol for seed treatment were three times lower than those on seedlings grown from seeds treated with diphenoconazole alone. The diphenoconazole + thymol mixture was highly active not only against this pathogen prevailing on barley seeds, but also caused a decrease in the prevalence of other pathogens of cereal root rot as effectively as after an individual use of this fungicide at a tenfold higher dose.

As a result of an experiment with wheat seedlings grown from seeds treated with a mixture of diphenoconazole and thymol, it was found that their combined use for seed treatment led to a stronger suppression of the disease on plants compared to its suppression on seedlings grown from seeds treated only diphenoconazole alone.

To determine whether the in vitro sensitized effect of PCF manifests itself in the field, wheat plants were sprayed with a mixture of PCF with tebuconazole in a dose that was 5 times lower than recommended for industrial treatments. The data on the first counts of the symptoms of the disease (2 counts on leaf damage and 1 count on stem damage) showed that the sensitizing effect of PCF detected in the laboratory also manifests itself in the field, at least at some stages of plant development. In particular, treatment with PCF alone did not lead to a decrease in the number of affected stems in phase 71, and the effectiveness of the low concentration of tebuconazole was at 28%. When applied at this concentration together with PCF, the effectiveness of this fungicide against S. nodorum increased to 49%.

In all cases of joint application of the same dose of tebuconazole together with PCF on leaves, stems and spike, almost the same antiseptoric effect was achieved as after application of a 5 times higher concentration of fungicide. Thus, field experiments showed that the combined use of PCF of strain FS-94 can reduce the dose of tebuconazole fungicide by 5 times without reducing its protective effect. On leaves treated with one fungicide, the average R value (degree of disease development) reached 50.5%, while after its combined use with thymol, the average R value was only 32.3%. In one experiment, the combined use was as effective as a 2 times higher concentration of tebuconazole. The suppressive effect of tebuconazole after combined use exceeded the expected additive effect by 20%.

When a wild strain of S. nodorum was cultured on a medium with diphenoconazole, a mutant was isolated whose growth was more intense than the growth of the original strain. At a concentration of this fungicide in a medium of 0.5 ppm, the average diameter of the colonies of the resistant mutant was 3 times greater than the diameter of the colonies of the original strain growing on similar media with fungicide. The growth of the latter stopped at a concentration of diphenoconazole of 1 ppm, and the growth of the mutant clone continued even in the presence of fungicide at a concentration of 5 ppm. To make sure that the resistance of this clone is due to genetic mutation, and not physiological adaptation, it was sown and grown on KGA without diphenoconazole. After passage on the KGA, the strain was again plated on the KGA with fungicide. The resistance of the strain did not change, which indicates that it is a true genetic mutant in resistance.

The combined use of diphenoconazole and thymol led to an increase in the sensitivity of the resistant mutant to the level of the natural (non-resistant) strain of S. nodorum. So, diphenoconazole at a concentration of 0.005 ppm inhibited the growth of the original strain by 23%), and the growth of the resistant mutant by 0.9%. When using diphenoconazole in the same concentration with thymol at a concentration of 10 ppm, which did not affect the development of the fungus, the growth of the mutant was suppressed by 20%.

The table shows the test results of the drug in the declared concentrations and proportions. In comparison, parameters are indicated that are beyond the scope of the declared, as well as a fungicide in its pure form without a chemosensitizer.

Table Fungicide, concentration, ppm Chemosensitization
torus, concentration, ppm Proportion Fungicide:
chemosensitizer Fungicidal effect,% The period of protective action, day one 2 3 four 5 Tebuconazole 0.1 Thymol 10.0 10: 1 64 fourteen 1,0 2,3-ADD 1.0 1: 1 25 fourteen 0.5 4-BOTH 200.0 1: 1 60 fourteen 20,0 FCL 20.0 5: 2 75 9 Comparison of tebuconazole 0.0025 Thymol 2.5 45: 1 8 5 FCL 0.2 7: 4 5 5 No additives 10 5 Difenoconazole 3000.0 Thymol 50.0 6: 1 80 fourteen 0.01 2,3-ADD 1.0 3: 2 36 fourteen 0.1 4-BOTH 900.0 1: 1 43 fourteen 0.01 FCL 20.0 9: 5 fifty 23 Comparison of diphenoconazole 0.005 2,3-ADD 0.05 3: 1 23 10 Thymol 0.3 25: 3 12 7 No additives - 25 10 one 2 3 four 5 Azoxystrobin 100.0 Thymol 10.0 1:10 41 fourteen 0.01 2,3-ADD 3.0 1: 1 48 fourteen 10.0 4-BOTH 1000.0 1: 1 58 fourteen 0.05 FCL 20.0 5: 1 35 twenty Comparison
azoxystrobin 0.004 4-BOTH 0.4 15: 1 13 7 FCL 0.2 1: 1 0 0 No additives - fifteen fourteen

As follows from the above data, the effect of a significant increase in the activity and duration of the protective effect is observed when using the claimed drug within the ranges of the concentration of the chemosensitizer solution and the proportion of the latter with the active agent.

Claims (1)

A composite preparation of fungicidal action to protect plants from pathogens, including those resistant to commercial fungicides, containing the active substance, which is used as a complex comprising strobilurins or triazoles at a concentration of 0.01-3000 ppm and a chemosensitizer at a concentration of 1-1000 ppm, taken in a ratio of 1: 1-10: 1, while the chemosensitizer is selected from 2,3-dioxibenzaldehyde, 4-hydroxybenzaldehyde, a solution of thymol in dimethyl sulfoxide or a filtrate of the culture fluid of the fungus strain Fusarium sambucinum FS-94.