Application of flavanones as fungicide synergists in plant disease control

Abstract

The present invention relates to the use of flavanones as fungicide synergists in plant disease control. Specifically, the fungicide synergists are used in combination with substituted aniline fungicides, strobilurin fungicides, triazole fungicides, and substituted benzene fungicides for disease control. Flavanones have a synergistic effect on fungicides. When mixed with fungicides, they can enhance the toxicity of fungicides, increase the sensitivity of resistant strains to fungicides, and improve the fungicide's effectiveness against drug-resistant plant pathogens indoors or in the field. Furthermore, the synergists can effectively reduce the amount of fungicide used, providing a new method for the development and application of new fungicide formulations.

Description

Technical Field

[0001] The present invention relates to the field of plant disease prevention and control, and in particular to the application of flavanone as a fungicide synergist in the treatment of multidrug resistance of pathogens caused by overexpression of cytochrome P450 genes. Background Art

[0002] Cytochrome P450 enzymes, as important enzymes of phase I metabolism, can convert chemical agents into more water-soluble and more easily excreted extracellular compounds through redox and other processes, thereby reducing plant toxicity. Studies have found that overexpression of P450 genes can lead to a significant decrease in the sensitivity of plant pathogens to uncouplers, methoxyacrylate fungicides, cytochrome bc1 Qi-site plastoquinone reductase inhibitors, β-tubulin inhibitors, histidine kinase inhibitors, triazole fungicides and multi-site fungicides, thus producing multidrug resistance in pathogens (Cheng, XK, Dai, T., Hu, ZH, Cui, TS, Wang, WZ, Han, P., et al. (2022). Cytochrome P450and glutathione S-transferase confer metabolic resistance to SYP-14288and multi-drug resistancein Rhizoctonia solani. Front. Microbiol. 13, 806339-806339). Once multidrug resistance (MDR) emerges in the field, disease control becomes even more difficult. Conventional management methods, such as rotating pesticides and mixing them, are unlikely to achieve the desired results, leading to environmental pollution and pesticide residues. Therefore, effective solutions are urgently needed to address MDR caused by the detoxification enzyme P450.

[0003] Detoxification enzyme inhibitors can effectively inhibit the activity of this enzyme, reducing the metabolism of pesticides in pathogens, increasing their sensitivity to pesticides, and restoring fungicide activity against resistant populations, thereby reducing pesticide application rates. This is an effective approach for managing multidrug resistance. Currently, there are few reports on this topic. The development and application of detoxification enzyme inhibitors as fungicide synergists will provide scientific insights and important insights for effectively reducing the damage caused by multidrug-resistant plant disease populations. Summary of the Invention

[0004] Based on the above-mentioned defects, the first purpose of the present invention is to provide the use of flavanones as fungicidal synergists in the management of multidrug resistance of plant diseases caused by overexpression of cytochrome P450 enzymes.

[0005] The plant disease pathogen is a Rhizoctonia solani that is resistant to two or more of oxidative phosphorylation uncouplers, mitochondrial respiration inhibitors, signal transduction inhibitors, β-tubulin inhibitors, ergosterol biosynthesis inhibitors, and multi-site inhibitors;

[0006] And / or, the pathogenic bacteria of the plant disease is Rhizoctonia solani that is resistant to two or more of substituted aniline fungicides, amide fungicides, methoxyacrylate fungicides, imidazole fungicides, pyrrolobenzene fungicides, benzimidazole fungicides, triazole fungicides and substituted benzene fungicides.

[0007] Preferably, the pathogenic bacteria of the plant disease are Rhizoctonia solani that is resistant to two or more of fluazinam (or bifenthion), azoxystrobin, cyazolin, fludioxonil, carbendazim, difenoconazole and thiophanate-methyl.

[0008] More specifically, the present invention provides the use of flavanones as fungicidal synergists in the prevention and treatment of diseases caused by Rhizoctonia solani.

[0009] Flavanone has a significant synergistic effect on a variety of fungicides with different mechanisms of action. Flavanone, also known as 2,3-dihydroflavonoid, has a molecular formula of C 15 H 12 O2, also known as Flavanone, CAS No. 487-26-3. Flavanone compounds are widely present in nature and exhibit many biopharmacological activities.

[0010] After flavanone is mixed with a fungicide, it is found that the mixture has a good synergistic effect on the fungicide's inhibition of the mycelial growth of a multidrug-resistant strain of Rhizoctonia solani, greatly improving the inhibition rate and significantly reducing the dosage of the fungicide.

[0011] The fungicide is a substituted aniline fungicide, a methoxyacrylate fungicide, a triazole fungicide and a substituted benzene fungicide.

[0012] Preferably, the substituted aniline fungicides are difenoconazole and fluazinam;

[0013] Or, the strobilurin fungicide is azoxystrobin;

[0014] Or, the triazole fungicide is difenoconazole;

[0015] Alternatively, the substituted benzene fungicide is chlorothalonil.

[0016] In the application method proposed by the present invention, the Rhizoctonia solani is a strain resistant to two or more of substituted aniline fungicides, strobilurin fungicides, triazole fungicides and substituted benzene fungicides;

[0017] Preferably, the Rhizoctonia solani is a strain resistant to two or more of difenoconazole, fluazinam, azoxystrobin, difenoconazole, and chlorothalonil; and / or, the Rhizoctonia solani is a strain resistant to two or more of substituted aniline fungicides, strobilurin fungicides, triazole fungicides, and substituted benzene fungicides. The application provided by the present invention has excellent antibacterial effects against these resistant strains.

[0018] The second object of the present invention is to provide a composition for preventing and treating multidrug-resistant diseases caused by overexpression of cytochrome P450 genes, comprising (consisting of) flavanones and a fungicide;

[0019] Preferably, the fungicide is a substituted aniline fungicide, a methoxyacrylate fungicide, a triazole fungicide or a substituted benzene fungicide.

[0020] The present invention unexpectedly discovered that flavanones can significantly enhance the antibacterial effects of substituted aniline fungicides, methoxyacrylate fungicides, triazole fungicides, and substituted benzene fungicides.

[0021] In the composition, preferably, the substituted aniline fungicide is diazinon or fluazinam.

[0022] Furthermore, the weight ratio of the flavanone to the substituted aniline fungicide dibenzimid is (1-5000):1. Within this range, the synergistic coefficient of the flavanone can reach a maximum of over 150. Preferably, the weight ratio is (100-5000):1, (20-5000):1, or (20-100):1.

[0023] Furthermore, the weight ratio of the flavanone to the substituted aniline fungicide fluazinam is (1-5000):1. Within this range, the synergistic coefficient of the flavanone can reach a maximum of 60 or more. Preferably, the weight ratio is (100-5000):1, (20-5000):1, or (20-100):1.

[0024] In the composition, preferably, the strobilurin fungicide is azoxystrobin.

[0025] Furthermore, the weight ratio of the flavanone to the strobilurin fungicide is (1-5000):1; within this range, the synergistic coefficient of the flavanone can reach above 60. Preferably, the weight ratio is (20-5000):1, (20-250):1 or (250-5000):1.

[0026] In the composition, preferably, the triazole fungicide is difenoconazole.

[0027] Furthermore, the weight ratio of the flavanone to the triazole fungicide is (1-5000):1; within this range, the synergistic coefficient of the flavanone can reach above 130. Preferably, the weight ratio is (20-5000):1, (20-100):1 or (100-5000):1.

[0028] In the composition, preferably, the substituted benzene fungicide is thiophanate-methyl.

[0029] Furthermore, the weight ratio of the flavanone to the substituted benzene fungicide is (0.4-500):1; within this range, the synergistic coefficient of the flavanone can reach above 39. Preferably, the weight ratio is (10-500):1, (10-50):1 or (50-500):1.

[0030] The present invention unexpectedly discovered that flavanones have a synergistic effect on substituted aniline fungicides, methoxyacrylate fungicides, triazole fungicides and substituted benzene fungicides. When mixed with fungicides, they can enhance the toxicity of the fungicides and restore the sensitivity of multidrug-resistant strains to the drugs. They can be used as synergists of fungicides and are used to control multidrug resistance in plant diseases caused by overexpression of cytochrome P450 enzymes.

[0031] The advantages of the present invention are:

[0032] 1. Flavanones have a synergistic effect on fungicides. When used in combination with fungicides, they can increase the toxicity of fungicides, restore the sensitivity of resistant strains to fungicides, enhance the control effect of fungicides on multidrug resistance of plant diseases caused by overexpression of P450 enzymes, and reduce the dosage of fungicides, providing a new method for the development and application of new formulations of existing fungicides.

[0033] 2. Flavanone compounds are widely found in nature and are active ingredients in many medicinal plants. They possess numerous biopharmacological activities, including antibacterial, anti-inflammatory, anti-tumor, antiviral, and antioxidant activities, and are environmentally friendly. This invention provides new uses for these compounds, including their potential application in agricultural disease control and offers an effective solution for managing multidrug resistance in plant diseases caused by overexpression of P450 enzymes. DETAILED DESCRIPTION

[0034] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0035] In the following embodiments, the “parts by mass” mentioned herein is a unit of weight as understood in the art, and may be “g”, “kg”, “mg”, “μg”, ​​etc.

[0036] The reagents involved in the following embodiments and test examples are disclosed as follows:

[0037] Bifenthionil (98%, Shenyang Chemical Research Institute Co., Ltd.), fluazinam (98%, Jiangsu Ruibang Agrochemical Co., Ltd.), azoxystrobin (96.5%, Jiangsu Huifeng Agrochemical Co., Ltd.), difenoconazole (96%, Jiangsu Xinnong Chemical Co., Ltd.), chlorothalonil (98.5%, Shandong Weifang Runfeng Chemical Co., Ltd.), flavanone (98%, Shanghai TCI Chemical Industry Development Co., Ltd.).

[0038] The strains were sourced as follows:

[0039] The sensitive strain X19 of Rhizoctonia solani was collected, isolated, purified and identified from diseased rice plants in the field, and stored in the Seed Pathology Fungicide Pharmacology Laboratory of China Agricultural University; the multidrug-resistant strain X19-7 was obtained by induction screening of dimethomorph from the sensitive strain X19 and can be obtained from the Seed Pathology Fungicide Pharmacology Laboratory of China Agricultural University (Cheng, XK, Man, XJ, Wang, ZT, Liang, L., Zhang, F., Wang, ZW, et al. (2020). Fungicide SYP-14288 inducing multi-drug resistance in Rhizoctonia solani. Plant Dis. doi: 10.1094 / PDIS-01-20-0048-RE). Previous studies have shown that X19-7's resistance to dimethomorph and multidrug resistance are caused by overexpression of cytochrome P450 enzymes. After testing, the EC of dimethomorph-resistant strain X19-7 was obtained. 50 The value was 0.083 μg / mL, and the resistance multiple was 19 times; the EC value of fluazinam against X19-7 was 0.083 μg / mL, and the resistance multiple was 19 times; 50 The value was 0.179 μg / mL; the EC of azoxystrobin against X19-7 50 The value was 0.054 μg / mL; the EC value of difenoconazole for X19-7 50 The value was 0.177 μg / mL; the EC value of chlorothalonil against X19-7 50 The value was 0.517 μg / mL. Compared with the sensitive strain X19, the multi-resistant strain X19-7 had significantly lower sensitivity to these fungicides with different mechanisms of action.

[0040] Example 1

[0041] This embodiment provides a composition for preventing and controlling plant diseases caused by Rhizoctonia solani, which is composed of 5000 parts by mass of flavanone and 1 part of diphenylpyralid.

[0042] Example 2

[0043] This embodiment provides a composition for preventing and controlling plant diseases caused by Rhizoctonia solani, which is composed of 100 parts by mass of flavanone and 1 part of diphenylpyralid.

[0044] Example 3

[0045] This embodiment provides a composition for preventing and controlling plant diseases caused by Rhizoctonia solani, which is composed of 20 parts by mass of flavanone and 1 part of diphenylpyralid.

[0046] Example 4

[0047] This embodiment provides a composition for preventing and controlling plant diseases caused by Rhizoctonia solani, which is composed of 1 part by mass of flavanone and 1 part by mass of bifenthion.

[0048] Application Example 1

[0049] This application example provides the use of flavanone as a fungicide synergist for the prevention and treatment of rice sheath blight, wherein the fungicide synergist and a substituted aniline fungicide are used in the form of a composition for the prevention and treatment of sheath blight.

[0050] Test subjects: the fungicide compositions provided in Examples 1-4, and a single dose of a substituted aniline fungicide (diphenylpyraclostrobin) and a single dose of flavanone.

[0051] Test method:

[0052] EC 50 Determination of: Dimethoprim and flavanone were compounded at ratios of 1:1, 1:20, 1:100 and 1:5000, respectively, and serial dilutions were performed. The final concentration range of dimethoprim used in the test was 0.00125-1μg / mL, and the final concentration range of flavanone was 0.01-50μg / mL. The mycelial growth rate method was used to determine the inhibition rate of fungicides on the expansion of colony diameter. Blank control, dimethoprim treatment, flavanone treatment, and dimethoprim and flavanone compound treatment were set up. Each treatment was repeated 3 times and cultured in the dark in a 25°C incubator. The colony diameter was measured after 5 days, and the inhibition rate of each treatment on the strain was calculated. The EC value of the compound solution at each ratio and the single-dose solution was also calculated. 50 value.

[0053] The inhibition rate was calculated according to the following formula:

[0054]

[0055] Synergistic effect determination: Determination of the EC of a single dose of dibenzamide and a single dose of flavanone against the multi-resistant strain X19-7 of Rhizoctonia solani 50 The Wadley method was used to evaluate the interaction degree after compounding. The formula used is as follows:

[0056]

[0057]

[0058] Among them, EC 50 (TH) is the theoretical value of the combination of fungicide and synergist, EC 50 (OB) is the observed value of the fungicide-synergist combination, the synergistic coefficient (SR) represents the degree of interaction between the fungicide and synergist, and A and B represent the proportions of the fungicide and synergist in the combination, respectively. An SR ≥ 1.5 indicates a synergistic effect between the two compounds; an SR < 0.5 indicates an antagonistic effect; and an SR between 0.5 and 1.5 indicates an additive effect.

[0059] Test results:

[0060] Table 1 shows the results of the synergistic effect of diphenylpyralid and flavanones. These results demonstrate that flavanones significantly enhance the toxicity of diphenylpyralid against the multi-resistant Rhizoctonia solani strain X19-7. When diphenylpyralid and flavanones were combined at ratios of 1:20, 1:100, and 1:5000, respectively, the SRs were 57.53, 159.26, and 1.75, all demonstrating high synergistic activity. The best synergistic effect was achieved when diphenylpyralid and flavanones were combined at a ratio of 1:100.

[0061] Table 1 The synergistic effect of flavanone on the inhibition of multi-resistant Rhizoctonia solani strain X19-7 by diphenylpyradan

[0062]

[0063] Note: “-” means not suitable.

[0064] Example 5

[0065] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 5000 parts by mass of flavanone and 1 part by mass of fluazinam.

[0066] Example 6

[0067] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 100 parts by mass of flavanone and 1 part by mass of fluazinam.

[0068] Example 7

[0069] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 20 parts by mass of flavanone and 1 part by mass of fluazinam.

[0070] Example 8

[0071] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 1 part by weight of flavanone and 1 part by weight of fluazinam.

[0072] Application Example 2

[0073] This application example provides the use of flavanone as a fungicide synergist for the prevention and treatment of rice sheath blight, wherein the fungicide synergist and a substituted aniline fungicide are used in the form of a composition for the prevention and treatment of sheath blight.

[0074] Test subjects: single dose of oxidative phosphorylation uncoupling agent (fluazinam), the composition provided in Examples 5-8, and single dose of flavanone.

[0075] Test method:

[0076] EC 50 Determination of the inhibitory effect: Fluazinam and flavanone were mixed at a ratio of 1:1, 1:20, 1:100, and 1:5000, and serially diluted. The final concentration range of fluazinam used in the experiment was 0.00125-1μg / mL, and the final concentration range of flavanone was 0.01-50μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC of the mixed solution and the single-dose solution at each ratio was calculated. 50 value.

[0077] Synergistic effect determination: The EC of fluazinam and flavanones against the multi-resistant strain X19-7 of Rhizoctonia solani were determined according to the method described in Application Example 1. 50 The Wadley method was used to evaluate the interaction degree after compounding.

[0078] Test results:

[0079] The results of the synergistic effect assay between fluazinam and flavanones are shown in Table 2. Flavanones significantly enhanced the toxicity of fluazinam against the multi-resistant Rhizoctonia solani strain X19-7. When fluazinam and flavanones were mixed at ratios of 1:20, 1:100, and 1:5000, the SRs were 3.97, 65.88, and 1.56, respectively, demonstrating high synergistic activity. The synergistic effect was greatest when fluazinam and flavanones were mixed at a ratio of 1:100.

[0080] Table 2 The synergistic effect of flavanone on the inhibition of fluazinam on the multi-resistant strain X19-7 of Rhizoctonia solani

[0081]

[0082]

[0083] Note: “-” means not suitable.

[0084] Example 9

[0085] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 5000 parts by mass of flavanone and 1 part by mass of azoxystrobin.

[0086] Example 10

[0087] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 250 parts by mass of flavanone and 1 part by mass of azoxystrobin.

[0088] Example 11

[0089] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 20 parts by mass of flavanone and 1 part by mass of azoxystrobin.

[0090] Example 12

[0091] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 1 part by mass of flavanone and 1 part by mass of azoxystrobin.

[0092] Application Example 3

[0093] This application example provides the application of flavanone as a fungicide synergist for the prevention and treatment of rice sheath blight, wherein the fungicide synergist and a strobilurin fungicide are used in the form of a composition for the prevention and treatment of sheath blight.

[0094] Test subjects: single-dose of strobilurin fungicide (azoxystrobin), the composition provided in Examples 9-12, and single-dose of flavanone.

[0095] Test method:

[0096] EC 50 Determination of the inhibitory effect: Azoxystrobin and flavanone were mixed at a ratio of 1:1, 1:20, 1:250, and 1:5000, respectively, and serially diluted. The final concentration range of the azoxystrobin used in the test was 0.00125-1μg / mL, and the final concentration range of the flavanone was 0.001-50μg / mL. At the same time, salicylic acid was added at a final concentration of 100μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC values ​​of the mixed solutions and single-dose solutions at each ratio were calculated. 50 value.

[0097] Synergistic effect determination: The EC of azoxystrobin and flavanones against the multi-resistant strain X19-7 of Rhizoctonia solani were determined according to the method described in Application Example 1. 50 The Wadley method was used to evaluate the interaction degree after compounding.

[0098] Test results:

[0099] The results of the synergistic effect of azoxystrobin and flavanones are shown in Table 3. Flavanones significantly enhanced the toxicity of azoxystrobin against the multi-resistant Rhizoctonia solani strain X19-7. When azoxystrobin and flavanones were mixed at a ratio of 1:20, 1:250, and 1:5000, the SRs were 55.09, 60.57, and 1.58, respectively, all demonstrating high synergistic activity. The best synergistic effect was observed when azoxystrobin and flavanones were mixed at a ratio of 1:250.

[0100] Table 3 The synergistic effect of flavanones on the inhibition of multi-resistant Rhizoctonia solani strain X19-7 by azoxystrobin

[0101]

[0102] Note: “-” means not suitable.

[0103] Example 13

[0104] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 5000 parts by mass of flavanone and 1 part by mass of difenoconazole.

[0105] Example 14

[0106] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 100 parts by mass of flavanone and 1 part by mass of difenoconazole.

[0107] Example 15

[0108] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 20 parts by mass of flavanone and 1 part by mass of difenoconazole.

[0109] Example 16

[0110] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 1 part by mass of flavanone and 1 part by mass of difenoconazole.

[0111] Application Example 4

[0112] This application example provides the application of flavanone as a fungicide synergist for the prevention and treatment of rice sheath blight, wherein the fungicide synergist and a triazole fungicide are used in the form of a composition for the prevention and treatment of sheath blight.

[0113] Test subjects: a single dose of a triazole fungicide (difenoconazole), the compositions provided in Examples 13-16, and a single dose of flavanone.

[0114] Test method:

[0115] EC 50Determination of the inhibitory effect: Difenoconazole and flavanone were mixed at a ratio of 1:1, 1:20, 1:100, and 1:5000, and serially diluted. The final concentration range of difenoconazole used in the experiment was 0.001-1μg / mL, and the final concentration range of flavanone was 0.001-50μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC values ​​of the mixed solutions and single-dose solutions at each ratio were calculated. 50 value.

[0116] Synergistic effect determination: The EC of difenoconazole and flavanones against the multi-resistant strain X19-7 of Rhizoctonia solani were determined according to the method described in Application Example 1. 50 The Wadley method was used to evaluate the interaction degree after compounding.

[0117] Test results:

[0118] The results of the synergistic effect of difenoconazole and flavanones are shown in Table 4. Flavanones significantly enhanced the toxicity of difenoconazole against the multi-resistant Rhizoctonia solani strain X19-7. When difenoconazole and flavanones were mixed at ratios of 1:20, 1:100, and 1:5000, the SRs were 24.76, 135.91, and 1.60, respectively, demonstrating high synergistic activity. The best synergistic effect was achieved when difenoconazole and flavanones were mixed at a ratio of 1:100.

[0119] Table 4 The synergistic effect of flavanones on the inhibition of Rhizoctonia solani multi-resistant strain X19-7 by difenoconazole

[0120]

[0121] Note: “-” means not suitable.

[0122] Example 17

[0123] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 500 parts by mass of flavanone and 1 part by mass of thiophanate-methyl.

[0124] Example 18

[0125] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 50 parts by mass of flavanone and 1 part by mass of thiophanate-methyl.

[0126] Example 19

[0127] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 10 parts by mass of flavanone and 1 part by mass of thiophanate-methyl.

[0128] Example 20

[0129] This embodiment provides a composition for preventing and controlling rice sheath blight, which is composed of 0.4 parts by weight of flavanone and 1 part by weight of thiophanate-methyl.

[0130] Application Example 5

[0131] This application example provides the application of flavanone as a fungicide synergist for the prevention and treatment of rice sheath blight, wherein the fungicide synergist and a substituted benzene fungicide are used in the form of a composition for the prevention and treatment of sheath blight.

[0132] Test subjects: a single dose of a substituted benzene fungicide (chlorothalonil), the compositions provided in Examples 17-20, and a single dose of flavanone.

[0133] Test method:

[0134] EC 50 Determination of the inhibitory effect: Chlorothalonil and flavanone were mixed at a ratio of 2.5:1, 1:10, 1:50 and 1:500, respectively, and serial dilutions were performed. The final concentration range of the chlorothalonil used in the test was 0.01-2.5 μg / mL, and the final concentration range of the flavanone was 0.01-50 μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC values ​​of the mixed solutions and single-dose solutions at each ratio were calculated. 50 value.

[0135] Synergistic effect determination: The EC of the compound of chlorothalonil and flavanone against the multi-resistant strain X19-7 of Rhizoctonia solani was determined according to the method described in Application Example 1. 50 The Wadley method was used to evaluate the interaction degree after compounding.

[0136] Test results:

[0137] Table 5 shows the results of the synergistic effect of chlorothalonil and flavanones. Flavanones significantly enhanced the toxicity of chlorothalonil against the multi-resistant Rhizoctonia solani strain X19-7. When chlorothalonil and flavanones were mixed at a ratio of 1:10, 1:50, and 1:500, respectively, the SRs were 7.65, 39.02, and 1.53, all demonstrating high synergistic activity. The synergistic effect was greatest when chlorothalonil and flavanones were mixed at a ratio of 1:50.

[0138] Table 5 The synergistic effect of flavanones on the inhibition of chlorothalonil on the multi-resistant strain X19-7 of Rhizoctonia solani

[0139]

[0140]

[0141] Note: “-” means not suitable.

[0142] While the present invention has been described in detail above, including general descriptions, specific embodiments, and tests, it will be readily apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, any such modifications and improvements, without departing from the spirit of the present invention, are intended to fall within the scope of the present invention.

Claims

1. Use of flavanones as fungicide synergists for fungicides in the prevention and control of plant diseases caused by Rhizoctonia solani; the fungicide is a strobilurin fungicide; the strobilurin fungicide is azoxystrobin; The weight ratio of the flavanone to the methoxyacrylate fungicide is (20-250):

1.

2. The use according to claim 1, characterized in that The pathogenic bacteria of the plant disease have overexpression of their cytochrome P450 genes, which leads to resistance to two or more of oxidative phosphorylation uncouplers, mitochondrial complex II inhibitors, mitochondrial complex III inhibitors, signal transduction inhibitors, β-tubulin inhibitors, ergosterol biosynthesis inhibitors and multi-site inhibitors.

3. The use according to claim 2, characterized in that The pathogenic bacteria of the plant disease have overexpression of their cytochrome P450 genes, which leads to resistance to two or more of substituted aniline fungicides, amide fungicides, methoxyacrylate fungicides, imidazole fungicides, pyrrolobenzene fungicides, benzimidazole fungicides, triazole fungicides and substituted benzene fungicides.

4. The use according to claim 3, characterized in that The pathogenic bacteria of the plant disease have overexpression of their cytochrome P450 genes, resulting in resistance to two or more of fluazinam, bifenthionil, thiophanate-methyl, azoxystrobin, cyazolin, fludioxonil, carbendazim, difenoconazole and thiophanate-methyl.

5. A composition for preventing and treating multidrug-resistant plant diseases caused by overexpression of cytochrome P450 genes of plant pathogens, characterized in that: including flavanones and fungicides; The fungicide is a methoxyacrylate fungicide; the methoxyacrylate fungicide is azoxystrobin; the weight ratio of the flavanone to the methoxyacrylate fungicide is (20-250):1.

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