A bactericidal composition for preventing and treating tobacco Fusarium root rot and its application

Abstract

The present invention belongs to the field of agricultural fungicides, and particularly relates to a bactericidal composition for preventing and controlling tobacco Fusarium root rot and its application. The active ingredients in the bactericidal composition are composed of difenoconazole and pyraclostrobin, and the mass ratio of difenoconazole to pyraclostrobin is 1:4. The composition has a significant synergistic effect. Adding the synergist tea saponin to the formulation can significantly improve the control effect of the formulation on tobacco Fusarium root rot, effectively reduce the dosage of the active ingredients, and slow down the generation of drug resistance of the pathogen.

Description

Technical Field

[0001] The present invention belongs to the field of agricultural fungicides, and particularly relates to the screening and application of agents for controlling tobacco Fusarium root rot. Background Art

[0002] Tobacco is an important cash crop in China. Tobacco root rot is one of the important diseases causing tobacco yield reduction. Fusarium commune and Fusarium oxysporum are the main pathogenic fungi causing tobacco root rot.

[0003] Difenoconazole, with the English common name Difenoconazole, has the molecular formula C 19 H 17 C l2 N3O3, a relative molecular mass of 406.263, and a CAS number of 119446 - 68 - 3, is a chemical pesticide applicable to the control of crop diseases such as rice, wheat, corn, tomato, pepper, beet, banana, and soybean. Its mechanism of action is to inhibit the synthesis of the fungal cell wall and the function of the cell membrane, thereby playing an antifungal role.

[0004] Pyraclostrobin, with the English common name pyraclostrobine, has the molecular formula C 19 H 18 ClN3O4, a relative molecular mass of 387.817, is a strobilurin fungicide. By inhibiting mitochondrial respiration, it causes cell death and has protective, therapeutic, and leaf penetration and conduction effects. It is mainly used to control various diseases caused by fungi on crops and has good control efficacy against wheat powdery mildew and scab. In addition to having a direct effect on pathogenic bacteria, it can also change the physiological phenomena of many crops, especially cereals, such as increasing the absorption of nitrogen elements, thereby promoting the rapid growth of crops and increasing crop yields, so as to achieve the goal of high crop yields.

[0005] The applicant's previous investigation found that the prior art has disclosed a bactericidal composition containing difenoconazole and pyraclostrobin, but there is no relevant report on the use of the composition for tobacco Fusarium root rot; and through querying the pesticide information network, there is also no relevant product registration of the composition for tobacco Fusarium root rot.

[0006] The applicant has selected a bactericidal composition with excellent bactericidal activity and synergistic effect against tobacco Fusarium root rot through agent screening. Summary of the Invention

[0007] The present invention provides a bactericidal composition for preventing and controlling tobacco Fusarium root rot and its application; the composition has a significant synergistic effect, can effectively reduce the dosage of active ingredients, and slow down the generation of pathogen drug resistance. The specific method is as follows:

[0008] The use of a bactericidal composition for preventing and controlling tobacco Fusarium root rot is characterized in that: the pathogens of the tobacco root rot are Fusarium commune and Fusarium oxysporum; the active ingredients in the bactericidal composition are composed of difenoconazole and pyraclostrobin, and the mass ratio of difenoconazole to pyraclostrobin is 1:2 - 1:4.

[0009] Fusarium commune, its taxonomic name is Fusarium commune G25-2, and it was deposited on January 23, 2024 at the China Center for Type Culture Collection, Wuhan University, Wuhan, Hubei Province, China, with the deposit number CCTCC NO: M 2024127.

[0010] Fusarium oxysporum, its taxonomic name is Fusarium oxysporum G29-3, and it was deposited on January 23, 2024 at the China Center for Type Culture Collection, Wuhan University, Wuhan, Hubei Province, China, with the deposit number CCTCC NO: M 2024128.

[0011] The bactericidal composition contains the synergist tea saponin and is prepared in the form of a pesticide formulation. The percentage content of the active ingredient in the pesticide formulation is 5 - 75%. The pesticide formulation is an emulsifiable concentrate, water dispersible granule, wettable powder, suspension concentrate, or oil suspension concentrate.

[0012] Advantageous technical effects of the present invention:

[0013] The present invention has screened out specific agents for tobacco Fusarium root rot, and has screened out a medicament composition with a synergistic effect and its ratio. The bactericidal composition of the present invention has a significant synergistic effect. Adding the synergist tea saponin to the formulation can significantly improve the control effect of the formulation on tobacco Fusarium root rot, can effectively reduce the dosage of active ingredients, and slow down the generation of pathogen drug resistance. Description of the Drawings

[0014] Figure 1 : Inhibitory diagram of mycelial growth of 6 fungicides against Fusarium commune

[0015] Figure 2 : Inhibitory diagram of mycelial growth of 6 fungicides against Fusarium oxysporum

[0016] Figure 3:Inhibitory effect of the combination of difenoconazole and pyraclostrobin on the mycelial growth of Fusarium commune

[0017] Figure 4 :Inhibitory effect of the combination of difenoconazole and pyraclostrobin on the mycelial growth of Fusarium oxysporum Detailed implementation manners

[0018] The present invention will be further described below in conjunction with specific embodiments.

[0019] The test materials are as follows:

[0020] (1) Test strains

[0021] The test pathogens of tobacco root rot (Fusarium commune CCTCC NO: M 2024127 and Fusarium oxysporum CCTCC NO: M 2024128) were provided by the strain bank of the College of Plant Protection, Anhui Agricultural University.

[0022] (2) Test agents

[0023] Technical materials: fludioxonil, fluazinam, cyenopyrafen, difenoconazole, pyraclostrobin, fluxapyroxad;

[0024] Reagents: methanol (analytical grade), 36% hydrochloric acid;

[0025] Example 1

[0026] Fungicide screening

[0027] The indoor toxicity of the test fungicides against Fusarium was determined by the mycelial growth rate method. The specific method is as follows:

[0028] (1) Weigh 0.05 g of the fungicide technical material into a 10 mL centrifuge tube, and use a 5 mL pipette to suck 5 mL of methanol and add it to shake until it is completely dissolved. This solution A is the 10000 mg / L mother liquor; according to the set plate concentration, dilute and configure several concentrations of the mother liquor;

[0029] (2) Shake the mother liquor well before adding the agent to the culture medium. According to the set plate concentration, suck 0.2 mL of the mother liquor from the corresponding mother liquor and add it to 200 mL of PDA culture medium, mix well and pour it evenly into 12 petri dishes with a diameter of 90 mm, and wait for the plate to cool and solidify;

[0030] (3) Select a colony with a colony diameter of about 2 / 3 of the petri dish, punch a 6 mm mycelial disc at the colony edge, pick up the mycelial disc and place it in the center of a 90 mm diameter petri dish, seal it, and invert the plate and put it into a 25 °C dark constant temperature incubator;

[0031] (4) When the diameter of the CK colonies grows to about 2 / 3 of the culture dish, measure the colony diameter at each concentration by the cross method;

[0032] (5) Obtain the inhibition rate, corresponding probability value, concentration logarithm, virulence regression equation, correlation coefficient, and EC 50 value through relevant software.

[0033] As Figure 1 shown in Table 1, the EC 50 values of the 6 fungicides against Fusarium commune in tobacco from small to large are fludioxonil (0.0589 mg / L), fluazinam (0.0919 mg / L), cyenopyrafen (0.1593 mg / L), difenoconazole (0.4740 mg / L), fluxapyroxad (1.0622 mg / L), and pyraclostrobin (1.2252 mg / L).

[0034] Table 1 Indoor toxicity determination of 6 fungicides against Fusarium commune

[0035]

[0036] As Figure 2 shown in Table 2, the EC 50 values of the 6 fungicides against Fusarium oxysporum in tobacco from small to large are fludioxonil (0.0237 mg / L), difenoconazole (0.1767 mg / L), fluazinam (0.1885 mg / L), pyraclostrobin (0.2979 mg / L), fluxapyroxad (1.9075 mg / L), and cyenopyrafen (2.2241 mg / L).

[0037] Table 2 Indoor toxicity determination of 6 fungicides against Fusarium oxysporum

[0038]

[0039]

[0040] According to the indoor toxicity determination of the 6 fungicides, 5 fungicides, namely fluazinam, fludioxonil, difenoconazole, pyraclostrobin, and cyenopyrafen, have good inhibitory effects on the colonies of Fusarium. Among them, the protective fungicides fludioxonil and fluazinam have lower EC 50The value is the smallest and the effect is the best. However, during the experiment, it was found that when the concentration of fludioxonil reached a certain level, the inhibitory effect would decrease instead as the concentration increased, and the chemical concentrations at the turning points of different strains were also different, so it should be used with caution. Fluazinam is a broad-spectrum and highly effective protective fungicide, which is extremely resistant to rain erosion and has a long residual effect period. It is suitable for use as a foliar spray pesticide. Moreover, existing data shows that its effect is not ideal in the pot experiment for pesticide efficacy control. Difenoconazole, pyraclostrobin, and cyenopyrafen are systemic fungicides. Among them, existing data shows that cyenopyrafen is prohibited from root irrigation during the seedling stage of crops, otherwise it is likely to cause serious phytotoxicity, and tobacco is prone to disease during the seedling stage, so it has certain limitations. After considering various factors, difenoconazole and pyraclostrobin were finally selected for the screening of compound agents.

[0041] Example 2

[0042] Screening of compound agents

[0043] The joint toxicity of compound agents with different ratios to Fusarium was determined by the method of Sun Yunpei:

[0044] Prepare stock solutions B and C with a concentration of 1000 mg / L. Pipette 10 mL of stock solution B and 1 mL of stock solution C and mix them to obtain a stock solution with a mass ratio of B:C of 10:1. Similarly, obtain solutions with ratios of 8:1, 6:1, 4:1, 2:1, 1:2, 1:4, 1:6, 1:8, and 1:10. The concentration of all solutions is 1000 mg / L.

[0045] The experiment was repeated 3 times.

[0046] Theoretical EC 50 value and synergistic coefficient SR, and the calculation methods are as follows:

[0047] Note: a: content of technical material A in the ratio; b: content of technical material B in the ratio; A1: EC 50 of technical material A; B1: EC 50 of technical material B.

[0048] Note: SR > 1.5 indicates synergistic effect;

[0049] 0.5 ≤ SR ≤ 1.5 indicates additive effect;

[0050] [[ID=3,6]]SR < 0.5 indicates antagonistic effect.

[0051] The specific experimental results of the screening of compound agents are summarized as follows:

[0052] (1) Toxicity determination results of the compound agent of difenoconazole and pyraclostrobin

[0053] As Figure 3As shown in Table 3, among the compounding ratios of difenoconazole and pyraclostrobin, all 10 compounding ratios have synergistic effects. The order of the synergistic coefficient from small to large is 1:10 < 8:1 < 10:1 < 6:1 < 4:1 < 1:2 < 2:1 < 1:8 < 1:6 < 1:4. Among them, the compounding ratio of 1:4 has the largest synergistic coefficient of 2.47, and the compounding ratio with the smallest synergistic coefficient is 1.52 for 1:10. The compounding ratios of 4:1, 1:2, 2:1, 1:8, 1:6, and 1:4 all have relatively high synergistic coefficients, with the synergistic coefficient above 2.0.

[0054] Table 3 Joint toxicity determination of difenoconazole and pyraclostrobin compound on Fusarium commune

[0055] <{

[0056] As Figure 4 As shown in Table 4, among the compounding ratios of difenoconazole and pyraclostrobin, 2 compounding ratios have synergistic effects. The order of the synergistic coefficient from small to large is 1:2 < 1:4. Among them, the compounding ratio of 1:4 has the largest synergistic coefficient of 1.67, and the compounding ratio with the smallest synergistic coefficient is 1.61 for 1:2. The compounding ratios of 10:1, 8:1, 6:1, 4:1, 2:1, 1:6, 1:8, and 1:10 all show additive effects, and the synergistic coefficients are all above 1.

[0057] Table 4 Joint toxicity determination of difenoconazole and pyraclostrobin compound on Fusarium oxysporum

[0058]

[0059]

[0060] To sum up, in the screening of all compound agents, the best compounding ratio finally determined is difenoconazole∶pyraclostrobin = 1∶4. Based on this, the preparation experiment of the preparation will continue.

[0061] Example 3: Field control effect of difenoconazole and pyraclostrobin compound agent on tobacco Fusarium root rot ))

[0062] Test crop: Tobacco variety "Jiyan 9", ridge width 1.2 m, plant spacing 0.6 m. <{

[0063] Test agents:

[0064] Test agent 1:

[0065] 35% difenoconazole·pyraclostrobin emulsifiable concentrate, containing the following components by weight percentage:

[0066] Difenoconazole 7%, Pyraclostrobin 28%, synergist tea saponin 2%, agricultural emulsifier 1601# 6%, Tween 80 2%, Ethylan NS-500LQ 2%, soybean oil to make up 100%.

[0067] Test agent 2:

[0068] 35% difenoconazole·pyraclostrobin suspension, containing the following components by weight percentage:

[0069] Difenoconazole 7%, Pyraclostrobin 28%, synergist tea saponin 2%, Morwet EFW 3%, Tersperse 4894 2%, xanthan gum 1%, ethylene glycol 4%, sodium benzoate 0.5%, organic bentonite 0.5%, deionized water to make up 100%.

[0070] Comparison agent 1:

[0071] 35% difenoconazole·pyraclostrobin emulsifiable concentrate, containing the following components by weight percentage:

[0072] Difenoconazole 7%, Pyraclostrobin 28%, agricultural emulsifier 1601# 6%, Tween 80 2%, Ethylan NS-500LQ 2%, soybean oil to make up 100%.

[0073] Comparison agent 2:

[0074] 35% difenoconazole·pyraclostrobin suspension, containing the following components by weight percentage:

[0075] Difenoconazole 7%, Pyraclostrobin 28%, Morwet EFW 3%, Tersperse 4894 2%, xanthan gum 1%, ethylene glycol 4%, sodium benzoate 0.5%, organic bentonite 0.5%, deionized water to make up 100%.

[0076] Comparison agent 3:

[0077] Tea saponin 2%, agricultural emulsifier 1601# 6%, Tween 80 2%, Ethylan NS-500LQ 2%, soybean oil to make up 100%.

[0078] Test method: Test plot: Ridge width 1.2m, plant spacing 0.6m; Each dosage has 4 replicates, and each plot is randomly arranged. Each plot has 50 tobacco plants. The medicine is applied by root irrigation, with clear water treatment as the control. The transplanting time is May 10, 2022, and the medicine is applied on May 25 and June 10 respectively, with a total of 2 applications.

[0079] All 50 tobacco plants in each plot are investigated at the harvest stage. The disease grading standard is as follows:

[0080] Grade 0, no disease, normal plant growth;

[0081] Level 1: The plant growth is basically normal or slightly dwarfed, with a small number of necrotic roots, and the middle and lower leaves turn chlorotic (or discolored);

[0082] Level 3: The height of the diseased plant is 1 / 4 - 1 / 3 shorter than that of the healthy plant, or half of the roots are necrotic, 1 / 2 - 2 / 3 or more of the leaves wilt, and the middle leaves have slightly dried tips and edges;

[0083] Level 5: The height of the diseased plant is 1 / 3 - 1 / 2 shorter than that of the healthy plant, most of the roots are necrotic, more than 2 / 3 wilt, and there are obvious dried tips and edges;

[0084] Level 7: The height of the diseased plant is more than 1 / 2 shorter than that of the healthy plant, all the leaves of the whole plant wither, all the roots are necrotic, and the secondary roots near the ground surface are significantly damaged;

[0085] Level 9: The diseased plant is basically dead.

[0086] Calculate the disease index and control effect according to the following formula.

[0087]

[0088]

[0089] Test results: As shown in Table 5, the control effects of Test Agent 1 and Test Agent 2 on tobacco Fusarium root rot are 90.2% and 89.4% respectively; the control effects of Comparative Agents 1, 2, and 3 on tobacco Fusarium root rot are 80.9%, 78.5%, and 2.1% respectively. According to the comparison, adding the synergist tea saponin to the preparation can significantly improve the control effect of the preparation on tobacco Fusarium root rot.

[0090] Table 5: Field control effects of the compound agent of difenoconazole and pyraclostrobin on tobacco Fusarium root rot

[0091] Treatment Dilution ratio Disease index Field control efficacy % Test agent 1 1000 1.82 90.2 Test agent 2 1000 1.97 89.4 Comparison agent 1 1000 3.56 80.9 Comparison agent 2 1000 4.01 78.5 Comparison agent 3 1000 18.25 2.1 CK - 18.64 -

[0092] The above content further elaborates on the present invention in combination with specific implementation manners. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as falling within the protection scope determined by the claims submitted for the present invention.

Claims

1. Use of a bactericidal composition for controlling tobacco Fusarium root rot, characterized in that: The pathogen causing tobacco root rot is Fusarium commune; the active ingredients in the bactericidal composition are composed of difenoconazole and pyraclostrobin, and the mass ratio of difenoconazole to pyraclostrobin is 1:2 - 1:4; The bactericidal composition also contains the synergist tea saponin and is prepared in the form of a pesticide preparation.

2. The use according to claim 1, wherein: The percentage content of the active ingredients in the pesticide preparation is 5 - 75%.

3. The use according to claim 2, wherein: The pesticide preparation is an emulsifiable concentrate, water dispersible granules, wettable powder, suspension concentrate, or oil suspension concentrate.

4. The use according to claim 2, wherein: The pesticide preparation is 35% difenoconazole·pyraclostrobin emulsifiable concentrate, containing the following components by weight percentage: difenoconazole 7%, pyraclostrobin 28%, synergist tea saponin 2%, agricultural emulsifier 1601# 6%, Tween 80 2%, Ethylan NS - 500LQ 2%, soybean oil to make up 100%; Or the pesticide preparation is 35% difenoconazole·pyraclostrobin suspension concentrate, containing the following components by weight percentage: difenoconazole 7%, pyraclostrobin 28%, synergist tea saponin 2%, Morwet EFW 3%, Tersperse 4894 2%, xanthan gum 1%, ethylene glycol 4%, sodium benzoate 0.5%, organic bentonite 0.5%, deionized water to make up 100%.

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