Composition taking flavanone as bactericide synergist and application of composition

Abstract

The invention relates to application of flavanone as a bactericidal synergist in plant disease control. Specifically, the bactericidal synergist, a substituted aniline bactericide, a methoxy acrylate bactericide, a triazole bactericide and a substituted benzene bactericide are jointly applied to prevention and treatment of diseases. Flavanone has a synergistic effect on the bactericide, and can enhance the toxicity of the bactericide, improve the sensitivity of a drug-resistant strain to the bactericide and promote the control effect of the bactericide on indoor or field drug-resistant phytopathogens when being mixed with the bactericide, and can effectively reduce the dosage of the bactericide. And a new method is provided for the development and application of the existing new bactericide preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plant disease control, and in particular to the application of flavanones as fungicide synergists in the management of pathogen multi-drug resistance caused by cytochrome P450 gene overexpression. BACKGROUND

[0002] Cytochrome P450 enzymes, as important enzymes of phase I metabolism, can convert chemical agents into compounds with stronger water solubility and more favorable for being excreted outside the cell through oxidation-reduction and other processes, thereby reducing plant toxicity. Previous studies have found that P450 gene overexpression can lead to a significant decrease in the sensitivity of plant pathogens to uncouplers, strobilurin fungicides, cytochrome bc1 Qi site plastoquinone reductase inhibitors, β-tubulin inhibitors, histidine kinase inhibitors, triazole fungicides, and multi-acting site fungicides, i.e., the development of pathogen multi-drug resistance (Cheng, X. K., Dai, T., Hu, Z. H., Cui, T. S., Wang, W. Z., Han, P., et al. (2022). Cytochrome P450 and glutathione S -transferase confer metabolic resistance to SYP-14288 and multi-drug resistance in Rhizoctonia solani . Front. Microbiol. 13, 806339-806339). Once multi-drug resistance occurs in the field, disease control becomes more difficult, and conventional management methods such as drug rotation and mixed application are difficult to achieve ideal results, which in turn will cause environmental pollution and pesticide residues. Therefore, effective solutions are urgently needed to address multi-drug resistance caused by detoxification enzymes P450.

[0003] Detoxification enzyme inhibitors can effectively inhibit the activity of the enzyme, reduce the metabolism of the agent in the pathogen, increase the sensitivity of the pathogen to the agent, and restore the activity of the fungicide to the resistant population, thereby reducing the amount of pesticide applied, which is an effective way to manage multi-drug resistance. Currently, there are few reports on this aspect, and the development and application of detoxification enzyme inhibitor fungicide synergists will provide scientific reference and important reference for effectively reducing the harm of plant disease multi-drug resistance populations. SUMMARY

[0004] Based on the above-mentioned defects, the first purpose of the present application is to provide the application of flavanones as fungicide synergists in the management of plant disease multi-drug resistance caused by cytochrome P450 enzyme overexpression.

[0005] The plant disease pathogen is resistant to two or more of oxidative phosphorylation uncouplers, mitochondrial respiration inhibitors, signal transduction inhibitors, beta-tubulin inhibitors, ergosterol biosynthesis inhibitors, and multi-site inhibitors. The plant disease pathogen is resistant to two or more of substituted anilide fungicides, amide fungicides, strobilurin fungicides, imidazole fungicides, pyrrole fungicides, benzimidazole fungicides, triazole fungicides, and substituted benzene fungicides.

[0006] Preferably, the plant disease pathogen is resistant to two or more of fluazinam (or, biphenam), azoxystrobin, cyazofamid, fludioxonil, carbendazim, difenoconazole, and chlorothalonil.

[0007] More particularly, the application provides the use of flavanone as a fungicide synergist in the prevention and treatment of diseases caused by Rhizoctonia solani.

[0008] Flavanone has a significant synergistic effect on a variety of fungicides with different mechanisms of action. Flavanone, also known as 2,3-dihydroflavone, has the molecular formula C 15 H 12 O2, English name Flavanone, CAS number 487-26-3. Flavanone compounds are widely present in nature and exhibit many biological and pharmacological activities.

[0009] The application found that flavanone has a good synergistic effect on fungicides in inhibiting the mycelial growth of multi-drug resistant strains of Rhizoctonia solani, greatly improves the inhibition rate, and can significantly reduce the use dose of fungicides.

[0010] The fungicide is a substituted anilide fungicide, a strobilurin fungicide, a triazole fungicide, and a substituted benzene fungicide.

[0011] Preferably, the substituted anilide fungicide is biphenam and fluazinam; Or, the strobilurin fungicide is azoxystrobin; Or, the triazole fungicide is difenoconazole; Or, the substituted benzene fungicide is chlorothalonil.

[0012] In the application method, the Rhizoctonia solani is resistant to two or more of substituted anilide fungicides, strobilurin fungicides, triazole fungicides, and substituted benzene fungicides. Preferably, the Rhizoctonia solani is a strain resistant to two or more of benthival, fluazinam, azoxystrobin, difenoconazole and chlorothalonil; and / or, the Rhizoctonia solani is a strain resistant to two or more of substituted anilide fungicides, strobilurin fungicides, triazole fungicides and substituted benzene fungicides. The application provided by the present application has excellent fungistatic effect on the above-mentioned resistant strains.

[0013] A second object of the present application is to provide a composition for preventing and treating the multi-drug resistance disease caused by overexpression of cytochrome P450 gene, comprising (consisting of) flavanone and fungicide; Preferably, the fungicide is substituted anilide fungicide, strobilurin fungicide, triazole fungicide or substituted benzene fungicide.

[0014] The present application surprisingly found that flavanone can significantly improve the fungistatic effect of substituted anilide fungicide, strobilurin fungicide, triazole fungicide and substituted benzene fungicide.

[0015] In the composition, preferably, the substituted anilide fungicide is benthival or fluazinam.

[0016] Further, the weight ratio of the flavanone and the substituted anilide fungicide benthival is (1-5000):1; within this range, the synergistic coefficient of flavanone can be up to 150 or more. Preferably, the weight ratio is (100-5000):1, (20-5000):1 or (20-100):1.

[0017] Further, the weight ratio of the flavanone and the substituted anilide fungicide fluazinam is (1-5000):1; within this range, the synergistic coefficient of flavanone can be up to 60 or more. Preferably, the weight ratio is (100-5000):1, (20-5000):1 or (20-100):1.

[0018] In the composition, preferably, the strobilurin fungicide is azoxystrobin.

[0019] Further, the weight ratio of the flavanone and the strobilurin fungicide is (1-5000):1; within this range, the synergistic coefficient of flavanone can be up to 60 or more. Preferably, the weight ratio is (20-5000):1, (20-250):1 or (250-5000):1.

[0020] In the composition, preferably, the triazole fungicide is difenoconazole.

[0021] Further, 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 130 or more. Preferably, the weight ratio is (20-5000):1, (20-100):1 or (100-5000):1.

[0022] In the composition, preferably, the substituted benzene fungicide is chlorothalonil.

[0023] Further, 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 39 or more. Preferably, the weight ratio is (10-500):1, (10-50):1 or (50-500):1.

[0024] The present application surprisingly finds that flavanone has a synergistic effect on substituted aniline fungicides, methoxy acrylate fungicides, triazole fungicides and substituted benzene fungicides. Mixing with fungicides can improve the virulence of fungicides, restore the sensitivity of multiple drug-resistant strains to drugs, and can be used as a synergist for fungicides for the treatment of plant diseases caused by overexpression of cytochrome P450 enzymes.

[0025] The present application has the advantages of: 1. Flavanone has a synergistic effect on fungicides. Mixing with fungicides can improve the virulence of fungicides, restore the sensitivity of drug-resistant strains to fungicides, enhance the control effect of fungicides on plant diseases caused by overexpression of P450 enzymes, and reduce the amount of fungicides, providing a new method for the development and application of existing fungicide formulations.

[0026] 2. Flavanone compounds exist widely in nature and are one of the effective components of various medicinal plants, having many biological and pharmacological activities such as bactericidal, anti-inflammatory, antitumor, antiviral and antioxidant activities, and are environmentally friendly. The present application provides a new use of the compounds, which can be used for disease control in the agricultural field and provides an effective solution for the treatment of plant diseases caused by overexpression of P450 enzymes. DETAILED DESCRIPTION

[0027] The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0028] In the following examples, "mass parts" are understood in the art as weight units, which can be "g", "kg", "mg", "µg", etc.

[0029] The reagents involved in the following examples and test examples are disclosed as follows: Bismuth subtilis (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 Xinong Chemical Co., Ltd.), chlorothalonil (98.5%, Shandong Weifang Runfeng Chemical Co., Ltd.), flavanone (98%, Shanghai TCI Chemical Industry Development Co., Ltd.).

[0030] The strains were sourced as follows: The susceptible strain X19 of Rhizoctonia solani was collected, isolated, purified, and identified from diseased rice plants in the field, and preserved in the Laboratory of Seed Pathology and Fungicide Pharmacology, China Agricultural University. The multidrug-resistant strain X19-7 was obtained from the susceptible strain X19 through induction and screening with difenoconazole, and can be obtained from the Laboratory of Seed Pathology and Fungicide Pharmacology, China Agricultural University (Cheng, XK, Man, XJ, Wang, ZT, Liang, L., Zhang, F., Wang, ZW, et al. (2020). FungicideSYP-14288 inducing multi-drug resistance in Rhizoctonia solani Plant Dis.doi: 10.1094 / PDIS-01-20-0048-RE). Previous studies have shown that the resistance of X19-7 to bifenthrin and multidrug resistance is due to the overexpression of cytochrome P450 enzymes. Testing revealed that bifenthrin's EC50 value for the resistant strain X19-7... 50 The value was 0.083 μg / mL, with a resistance fold of 19-fold; the EC50 of fluazinam against X19-7 was... 50 The value was 0.179 μg / mL; the EC50 of azoxystrobin against X19-7 was... 50 The value was 0.054 μg / mL; the EC50 of difenoconazole against X19-7 was... 50 The value was 0.177 μg / mL; chlorothalonil's EC50 against X19-7 was... 50 The value was 0.517 μg / mL. Compared with the sensitive strain X19, the polyclonal resistant strain X19-7 showed significantly reduced sensitivity to these different types of fungicides with different mechanisms of action.

[0031] Example 1 This embodiment provides a control composition for plant diseases caused by Rhizoctonia solani, which consists of 5000 parts by weight of flavanone and 1 part by weight of bifenthrin. Example

[0032] This embodiment provides a control composition for plant diseases caused by Rhizoctonia solani, which consists of 100 parts by weight of flavanone and 1 part by weight of bifenthrin. Example

[0033] This embodiment provides a control composition for plant diseases caused by Rhizoctonia solani, which consists of 20 parts by weight of flavanone and 1 part by weight of bifenthrin. Example

[0034] This embodiment provides a control composition for plant diseases caused by Rhizoctonia solani, which consists of 1 part flavanone and 1 part difenoconazole by weight.

[0035] Application Example 1 This application example provides the use of flavanones as a fungicide synergist in the control of rice sheath blight, wherein the fungicide synergist is used in combination with a substituted aniline fungicide for the control of sheath blight.

[0036] Test subjects: the bactericidal compositions provided in Examples 1-4, and single agents of substituted aniline bactericides (bifenthrin) and flavanones.

[0037] Test method: EC 50 Determination: Bismuth subtilis and flavanone were mixed at ratios of 1:1, 1:20, 1:100, and 1:5000, and serially diluted. The final concentration range of bismuth subtilis was 0.00125-1 μg / mL, and the final concentration range of flavanone was 0.01-50 μg / mL. The inhibition rate of fungicide on colony diameter expansion was determined using the mycelial growth rate method. Blank control, bismuth subtilis treatment, flavanone treatment, and bismuth subtilis and flavanone mixture treatment were set up, with each treatment replicated three times. The fungicides were incubated in the dark at 25℃ for 5 days, and the colony diameter was measured. The inhibition rate of each treatment on the strain was calculated, and the EC50 of each ratio of the mixed solution and the single agent solution was calculated. 50 value.

[0038] The inhibition rate is calculated using the following formula:

[0039] Synergistic effect assay: The EC50 of the combined agent of bispyribac-methyl and flavanone against the multi-resistant strain X19-7 of Rhizoctonia solani was determined. 50 The interaction value was used to evaluate the degree of interaction after complexation according to the Wadley method. The formula used is as follows:

[0040] Among them, EC 50 (TH) represents the theoretical value of a combination of bactericide and synergist, EC 50(OB) represents the actual observed value of the combination of fungicide and synergist. The synergistic coefficient SR represents the degree of interaction between the fungicide and synergist. A and B represent the proportions of the fungicide and synergist in the combination, respectively. If SR ≥ 1.5, it indicates that the two have a synergistic effect; if SR < 0.5, it indicates that the two have an antagonistic effect; if SR is between 0.5 and 1.5, it indicates that the two have an additive effect.

[0041] Experimental results: The synergistic effect of bifenthrin and flavanone is shown in Table 1. The results indicate that flavanone significantly enhances the toxicity of bifenthrin against the multi-resistant strain X19-7 of Rhizoctonia solani. When bifenthrin and flavanone are combined at ratios of 1:20, 1:100, and 1:5000, the SR values ​​are 57.53, 159.26, and 1.75, respectively, all showing high synergistic effects. The optimal synergistic effect is observed when bifenthrin and flavanone are combined at a ratio of 1:100.

[0042] Table 1. Synergistic effect of flavanones on the inhibition of multi-resistant strain X19-7 of Rhizoctonia solani by difenoconazole. Treatment Boscalid: Flavanone EC 50 (μg / mL) SR Boscalid 1：0 0.083 - Flavanone 0：1 37.037 - Boscalid + Flavanone 1：5000 19.468 1.75 Boscalid + Flavanone 1：100 0.043 159.26 Boscalid + Flavanone 1：20 0.029 57.53 Boscalid + Flavanone 1：1 0.128 1.29 Note: "-" indicates that it is not suitable.

[0043] Example 5 This embodiment provides a composition for the control of rice sheath blight, consisting of 5000 parts by weight of flavanone and 1 part by weight of fluazinam.

[0044] Example 6 This embodiment provides a composition for the control of rice sheath blight, consisting of 100 parts by weight of flavanone and 1 part by weight of fluazinam.

[0045] Example 7 This embodiment provides a composition for the control of rice sheath blight, consisting of 20 parts by weight of flavanone and 1 part by weight of fluazinam.

[0046] Example 8 This embodiment provides a composition for the control of rice sheath blight, which consists of 1 part flavanone and 1 part fluazinam by weight.

[0047] Application Example 2 This application example provides the use of flavanones as a fungicide synergist in the control of rice sheath blight, wherein the fungicide synergist is used in combination with a substituted aniline fungicide for the control of sheath blight.

[0048] Test subjects: oxidative phosphorylation uncoupling agent (fluridinium), the compositions provided in Examples 5-8, and flavanone agents.

[0049] Test method: EC 50 Determination: Fluazinam and flavanone were compounded at ratios of 1:1, 1:20, 1:100, and 1:5000, and serially diluted. The final concentration range of fluazinam used in the experiment was 0.00125-1 μg / mL, and the final concentration range of flavanone was 0.01-50 μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC50 of each compounded drug solution and single-dose drug solution was calculated. 50 value.

[0050] Synergistic effect assay: The EC50 of fluazinam and flavanone alone against Rhizoctonia solani multi-resistant strain X19-7 was determined according to the method described in Application Example 1. 50 The value was used to evaluate the degree of interaction after complexation according to the Wadley method.

[0051] Experimental results: The results of the synergistic effect determination of fluazinam and flavanone are shown in Table 2. Flavanone significantly enhanced the virulence of fluazinam against the polyresistant strain X19-7 of Rhizoctonia solani. When fluazinam and flavanone were combined at ratios of 1:20, 1:100, and 1:5000, the SR values ​​were 3.97, 65.88, and 1.56, respectively, all showing high synergistic effects. Furthermore, the synergistic effect was greatest when fluazinam and flavanone were combined at a ratio of 1:100.

[0052] Table 2 Synergistic effect of flavanones on fluazinam's inhibition of multi-resistant strain X19-7 of Rhizoctonia solani. Treatment Flufenoxuron: Flavanone EC 50 (μg / mL) SR Flufenoxuron 1：0 0.179 - Flavanone 0：1 37.037 - Flufenoxuron + Flavanone 1：5000 22.851 1.56 Flufenoxuron + Flavanone 1：100 0.185 65.88 Flufenoxuron + Flavanone 1：20 0.863 3.97 Flufenoxuron + Flavanone 1：1 0.272 1.31 Note: "-" indicates that it is not suitable.

[0053] Example 9 This embodiment provides a composition for the control of rice sheath blight, consisting of 5000 parts by weight of flavanone and 1 part by weight of azoxystrobin.

[0054] Example 10 This embodiment provides a composition for the control of rice sheath blight, consisting of 250 parts by weight of flavanone and 1 part by weight of azoxystrobin.

[0055] Example 11 This embodiment provides a composition for the control of rice sheath blight, consisting of 20 parts by weight of flavanone and 1 part by weight of pyraclostrobin.

[0056] Example 12 This embodiment provides a composition for the control of rice sheath blight, consisting of 1 part by weight of flavanone and 1 part by weight of azoxystrobin.

[0057] Application Example 3 This application example provides the use of flavanones as a fungicide synergist in the control of rice sheath blight, wherein the fungicide synergist is applied in combination with a methoxyacrylate fungicide for the control of sheath blight.

[0058] Test subjects: methoxyacrylate fungicide (pyraclostrobin) single agent, the composition provided in Examples 9-12, and flavanone single agent.

[0059] Test method: EC 50 Determination: Azoxystrobin and flavanone were compounded at ratios of 1:1, 1:20, 1:250, and 1:5000, and serially diluted. The final concentration range of azoxystrobin used in the experiment was 0.00125-1 μg / mL, and the final concentration range of flavanone was 0.001-50 μg / mL. Salicylic acid was added simultaneously at a final concentration of 100 μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC50 of each compounded solution and single-agent solution was calculated. 50 value.

[0060] Synergistic effect test: The EC50 of azoxystrobin single agent and flavanone single agent combined against Rhizoctonia solani multi-resistant strain X19-7 was determined according to the method described in Application Example 1. 50 The value was used to evaluate the degree of interaction after complexation according to the Wadley method.

[0061] Experimental results: The results of the synergistic effect determination of azoxystrobin and flavanone are shown in Table 3. Flavanone significantly enhanced the toxicity of azoxystrobin against the polyresistant strain X19-7 of Rhizoctonia solani. When azoxystrobin and flavanone were combined at ratios of 1:20, 1:250, and 1:5000, the SR values ​​were 55.09, 60.57, and 1.58, respectively, all showing high synergistic effects. The synergistic effect was best when azoxystrobin and flavanone were combined at a ratio of 1:250.

[0062] Table 3. Synergistic effect of flavanones on the inhibition of Rhizoctonia solani multi-resistant strain X19-7 by azoxystrobin Treatment Azoxystrobin: Flavanone EC 50 (μg / mL) SR Azoxystrobin 1：0 0.054 - Flavanone 0：1 37.037 - Azoxystrobin + Flavanone 1：5000 20.676 1.58 Azoxystrobin + Flavanone 1：250 0.164 60.57 Azoxystrobin + Flavanone 1：20 0.020 55.09 Azoxystrobin + Flavanone 1：1 0.324 0.33 Note: "-" indicates that it is not suitable.

[0063] Example 13 This embodiment provides a composition for the control of rice sheath blight, consisting of 5000 parts by weight of flavanone and 1 part by weight of difenoconazole.

[0064] Example 14 This embodiment provides a composition for the control of rice sheath blight, consisting of 100 parts by weight of flavanone and 1 part by weight of difenoconazole.

[0065] Example 15 This embodiment provides a composition for the control of rice sheath blight, consisting of 20 parts by weight of flavanone and 1 part by weight of difenoconazole.

[0066] Example 16 This embodiment provides a composition for the control of rice sheath blight, which consists of 1 part flavanone and 1 part difenoconazole by weight.

[0067] Application Example 4 This application example provides the use of flavanones as a fungicide synergist in the control of rice sheath blight, wherein the fungicide synergist is used in combination with a triazole fungicide for the control of sheath blight.

[0068] Test subjects: triazole fungicide (difenoconazole) single agent, the composition provided in Examples 13-16, and flavanone single agent.

[0069] Test method: EC 50 Determination: Difenoconazole and flavanone were compounded at ratios of 1:1, 1:20, 1:100, and 1:5000, and serially diluted. The final concentration range of difenoconazole used in the experiment was 0.001-1 μg / mL, and the final concentration range of flavanone was 0.001-50 μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC50 of each compounded solution and single-dose solution was calculated. 50 value.

[0070] Synergistic effect assay: The EC50 of difenoconazole alone and flavanone alone against Rhizoctonia solani multi-resistant strain X19-7 was determined according to the method described in Application Example 1. 50 The value was used to evaluate the degree of interaction after complexation according to the Wadley method.

[0071] Experimental results: The results of the synergistic effect determination of difenoconazole and flavanone are shown in Table 4. Flavanone significantly enhanced the virulence of difenoconazole against the multi-resistant strain X19-7 of Rhizoctonia solani. When difenoconazole and flavanone were combined at ratios of 1:20, 1:100, and 1:5000, the SR values ​​were 24.76, 135.91, and 1.60, respectively, all showing high synergistic effects. The optimal synergistic effect was observed when difenoconazole and flavanone were combined at a ratio of 1:100.

[0072] Table 4. Synergistic effect of flavanones on difenoconazole in inhibiting the multi-resistant strain X19-7 of Rhizoctonia solani. Treatment Difenoconazole: Flavanone EC 50 (μg / mL) SR Difenoconazole 1：0 0.177 - Flavanone 0：1 37.037 - Difenoconazole + Flavanone 1：5000 22.291 1.60 Difenoconazole + Flavanone 1：100 0.089 135.91 Difenoconazole + Flavanone 1：20 0.137 24.76 Difenoconazole + Flavanone 1：1 1.482 0.24 Note: "-" indicates that it is not suitable.

[0073] Example 17 This embodiment provides a composition for the control of rice sheath blight, consisting of 500 parts by weight of flavanone and 1 part by weight of chlorothalonil.

[0074] Example 18 This embodiment provides a composition for the control of rice sheath blight, consisting of 50 parts by weight of flavanone and 1 part by weight of chlorothalonil.

[0075] Example 19 This embodiment provides a composition for the control of rice sheath blight, consisting of 10 parts by weight of flavanone and 1 part by weight of chlorothalonil.

[0076] Example 20 This embodiment provides a composition for the control of rice sheath blight, which consists of 0.4 parts by weight of flavanone and 1 part by weight of chlorothalonil.

[0077] Application Example 5 This application example provides the use of flavanones as a fungicide synergist in the control of rice sheath blight, wherein the fungicide synergist is used in combination with a substituted benzene fungicide for the control of sheath blight.

[0078] Test subjects: single agent of benzene-substituted fungicide (chlorothalonil), the compositions provided in Examples 17-20, and single agent of flavanone.

[0079] Test method: EC 50 Determination: Chlorothalonil and flavanone were compounded at ratios of 2.5:1, 1:10, 1:50, and 1:500, and serially diluted. The final concentration range of chlorothalonil used in the experiment was 0.01-2.5 μg / mL, and the final concentration range of flavanone was 0.01-50 μg / mL. The inhibition rate was determined according to the method described in Application Example 1, and the EC50 of each compound solution and single-agent solution was calculated. 50 value.

[0080] Synergistic effect test: The EC50 of the chlorothalonil single agent and the flavanone single agent combined with the chlorothalonil single agent against the multi-resistant strain X19-7 of Rhizoctonia solani was determined according to the method described in Application Example 1. 50 The value was used to evaluate the degree of interaction after complexation according to the Wadley method.

[0081] Experimental results: The results of the synergistic effect determination of chlorothalonil and flavanone are shown in Table 5. Flavanone significantly enhanced the virulence of chlorothalonil against the multi-resistant strain X19-7 of Rhizoctonia solani. When chlorothalonil and flavanone were combined at ratios of 1:10, 1:50, and 1:500, the SR values ​​were 7.65, 39.02, and 1.53, respectively, all showing high synergistic effects. The synergistic effect was best when chlorothalonil and flavanone were combined at a ratio of 1:50.

[0082] Table 5. Synergistic effect of flavanones on the inhibition of multi-resistant strain X19-7 of Rhizoctonia solani by chlorothalonil Treatment Chlorothalonil: Flavanone EC 50 (μg / mL) SR Chlorothalonil 1：0 0.517 - Flavanone 0：1 37.037 - Chlorothalonil + Flavanone 1：500 21.255 1.53 Chlorothalonil + Flavanone 1：50 0.398 39.02 Chlorothalonil + Flavanone 1：10 0.652 7.65 Chlorothalonil + Flavanone 2.5：1 1.647 0.44 Note: "-" indicates that it is not suitable.

[0083] Although the present invention has been described in detail above from three aspects: general description, specific implementation, and experiments, some modifications or improvements can be made based on the present invention, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. Use of flavanone as fungicide synergist in the prevention of plant diseases caused by Rhizoctonia solani; the fungicide is one or more of substituted anilide fungicides, triazole fungicides and substituted benzene fungicides; The substituted anilide fungicide is bifenahm; The triazole fungicide is difenoconazole; The substituted benzene fungicide is chlorothalonil; The weight ratio of the flavanone to the substituted anilide fungicide is (20-100): 1; The weight ratio of the flavanone to the triazole fungicide is (20-100): 1; The weight ratio of the flavanone to the substituted benzene fungicide is (10-50):

1.

2. Use according to claim 1, characterized in that, The pathogenic bacteria of the plant disease cause 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 due to overexpression of cytochrome P450 genes.

3. Use according to claim 2, characterized in that, The pathogenic bacteria of the plant disease cause resistance to two or more of substituted anilide fungicides, amide fungicides, strobilurin fungicides, imidazole fungicides, pyrrole fungicides, benzimidazole fungicides, triazole fungicides and substituted benzene fungicides due to overexpression of cytochrome P450 genes.

4. Use according to claim 3, characterized in that, The pathogenic bacteria of the plant disease cause resistance to two or more of fluazinam, bifenahm, thifluzamide, azoxystrobin, cyazofamid, fludioxonil, carbendazim, difenoconazole and chlorothalonil due to overexpression of cytochrome P450 genes.

5. A composition for the control of plant diseases caused by overexpression of cytochrome P450 genes of plant pathogenic fungi, characterized in that, The fungicide comprises flavanone and fungicide; The fungicide is one or more of substituted anilide fungicides, strobilurin fungicides, triazole fungicides and substituted benzene fungicides; the substituted anilide fungicide is bifenahm; the strobilurin fungicide is azoxystrobin; the triazole fungicide is difenoconazole; the substituted benzene fungicide is chlorothalonil; the weight ratio of the flavanone to the substituted anilide fungicide is (20-100): 1; The weight ratio of the flavanone to the triazole fungicide is (20-100): 1; The weight ratio of the flavanone to the substituted benzene fungicide is (10-50): 1.

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