A bactericidal composition for preventing and controlling corn bacterial wilt

Abstract

The present invention belongs to the technical field of corn bacterial wilt prevention and control, and specifically relates to a fungicide composition for preventing and controlling corn bacterial wilt. The fungicide composition comprises a compound of psoralen and zoxamide or silthiopyrad as active ingredients. The fungicide composition, which combines psoralen with zoxamide or silthiopyrad, exhibits a co-toxicity coefficient greater than 120 against corn bacterial wilt pathogens, demonstrating a synergistic effect. Compared to single zoxamide or silthiopyrad, the control efficacy is significantly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of corn bacterial wilt prevention and treatment, and particularly relates to a fungicide composition for preventing and treating corn bacterial wilt. Background Art

[0002] Corn bacterial wilt is also known as corn stalk rot. It is the main disease after corn head smut, corn leaf spot and corn leaf spot. According to the different types of pathogens, it can be divided into bacterial stalk rot and fungal stalk rot. According to research, the bacterial stalk rot in Henan Province is caused by the maize pathogenic variant of Erwinia chrysanthemi ( Erwinia chrysanthemi pv.zeae The disease caused by Sabet Victoria primarily affects the leaf sheaths and stems. Typical symptoms include waterlogging, decay, and softening of the central leaf sheaths and stems, accompanied by a strong foul odor. In the early stages of this bacterial corn stalk rot, plants generally fail to ear and set seeds, and in the later stages, organs above the affected area wither and die.

[0003] At present, there are few fungicides for plant bacterial diseases, and with the long-term irrational use of single ingredients, there is a problem of drug resistance. Therefore, there is an urgent need to develop fungicides for preventing and controlling plant bacterial diseases, especially for preventing and controlling corn wilt.

[0004] Psoralen is a funan coumarin compound derived from the fruit of the leguminous plant Psoralea corylifolia. It is a colorless, needle-shaped crystal (in ethanol) that is soluble in ethanol and chloroform and slightly soluble in water, ether, and petroleum ether. Patent CN110178849B discloses the use of psoralen in preventing and controlling plant bacterial diseases. The patent states that psoralen can effectively inhibit the growth of Xanthomonas fungi, including Xanthomonas oryzae, Xanthomonas oryzae bacterial leaf streak, and black rot of cruciferous vegetables, and is therefore suitable as an active ingredient in a botanical fungicide.

[0005] The inventors combined psoralen with zoxamide or silthiopyrad and found that within a certain mass ratio range, the combined formula exhibited a synergistic effect in inhibiting the growth of bacterial stem rot pathogens, providing insights into the development of new fungicides. Currently, there are no reports on the combination of psoralen with zoxamide or silthiopyrad.

[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0007] The object of the present invention is to provide a fungicide composition for preventing and controlling corn bacterial wilt, which can overcome the problems existing in the use of a single-component fungicide.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A bactericidal composition, wherein the active ingredients of the bactericidal composition are compounded with psoralen and zoxamide or silthiopyrad.

[0010] More specifically, the mass ratio of psoralen to zoxamide is 1-40:10-1.

[0011] More specifically, the mass ratio of psoralen to silthiopyrad is 12:9-1.

[0012] The present invention also provides application of the bactericidal composition in preventing or controlling corn bacterial wilt.

[0013] The present invention also provides a fungicide, which comprises auxiliary components and the fungicide composition.

[0014] More specifically, in the fungicide, the mass of the fungicide composition accounts for 0.5-45% of the mass of the fungicide.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The fungicide composition of the present invention is a compound of psoralen with zoxamide or silthiopyrad, and the co-toxicity coefficient against corn bacterial wilt is greater than 120, showing a synergistic effect. Compared with single zoxamide or silthiopyrad, the control effect is significantly improved, the amount of active ingredients used can be reduced, the production cost and the residual amount of pesticide active ingredients in the field can be reduced, and it is of great significance to the sustainable development of the ecological environment.

[0017] (2) The bactericidal composition of the present invention can expand the bactericidal spectrum and can delay the development of drug resistance in pathogens to a certain extent, thereby reducing the risk of drug resistance and facilitating the comprehensive prevention and control of disease resistance. It has a high prospect for promotion and application. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solution of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

[0019] Example: Indoor activity test

[0020] 1. Test pathogens

[0021] The samples of corn bacterial wilt were collected and isolated, purified and identified in the laboratory. The pathogen was identified as Erwinia chrysanthemi pv. maize ( Erwinia chrysanthemi pv.zeae (Sabet) Victoria).

[0022] 2. Culture medium

[0023] LB liquid medium: 10.0 g of tryptone, 10.0 g of NaCl, 5.0 g of yeast extract, adjust the pH to 7.0, and add water to make up to 1000 mL.

[0024] LB solid medium: 10.0 g tryptone, 10.0 g NaCl, 5.0 g yeast extract, 18.0 g agar, adjust the pH to 7.0, and add water to 1000 mL.

[0025] 3. Test agents

[0026] 98% psoralen technical, 97% benzylpyraclostrobin technical, 98% silthiopyrad technical, all of the above agents are commercially available.

[0027] After dissolving the test agents, set up multiple groups of ratios. For each single agent and each group of mixed agents, set up 5 series of mass concentration gradients according to the equal ratio method and set aside.

[0028] 4. Test methods

[0029] The inhibition zone method was used to determine the virulence of single-dose stock solutions and proportioned mixtures against the test strain Erwinia chrysanthemi pv. maydis.

[0030] Pick 2 loops of colonies and inoculate them into LB liquid medium, shake and culture at 28°C and 180 rpm until OD 600 The value was 0.6, and the concentration of bacterial suspension was adjusted to 3×10 8 cfu / mL. Mix the prepared bacterial suspension and sterilized LB solid medium cooled to about 45-50°C at a volume ratio of 1:30. Pour 15 mL into a 9 cm diameter Petri dish. After cooling and solidification, the plate containing bacteria is obtained.

[0031] Use a hole punch to punch out 5mm diameter sterile drug-susceptibility filter paper discs (each disc absorbs approximately 20μL of water). Place the discs on bacterial plates. Place two discs with 15μL of solution and one disc with an equal amount of sterile water (blank control) on each plate. Arrange the three discs in an equilateral triangle. Repeat 3-5 times per treatment. After incubation at 28°C for 48 hours, measure the diameter of the inhibition zone using the cross-hatch method and calculate the inhibition rate.

[0032]

[0033] 4. Data Analysis

[0034] The concentration of the drug was converted into a logarithmic value, and the corresponding inhibition rate was converted into a probability value. Then regression analysis was performed to calculate the EC of each treatment agent. 50 , the co-toxicity coefficient (CTC) of the mixture was calculated according to Sun Yunpei's method.

[0035]

[0036] In the above formula: ATI --The measured toxicity index of the mixture; S --EC of standard medicine 50 , unit is mg / L; M --EC of the mixture 50 , unit is mg / L.

[0037]

[0038] In the above formula: TTI --Theoretical toxicological index of the mixture; TI A --Toxicity index of agent A; P A --The percentage of agent A in the mixture, in percentage (%); TI B --Toxicity index of agent B; P B --The percentage of agent B in the mixture, in percentage (%).

[0039]

[0040] In the above formula: CTC --Co-toxicity coefficient; ATI --Measured toxicity index of the mixture; TTI --Theoretical toxicity index of the mixture.

[0041] 5. Effect evaluation

[0042] The synergistic effect of the agents was evaluated based on the calculated co-toxicity coefficient (CTC value): CTC ≤ 80 indicates an antagonistic effect; 80 < CTC < 120 indicates an additive effect; and CTC ≥ 120 indicates a synergistic effect. The results are shown in Table 1-2.

[0043] Table 1 Indoor bioactivity test of psoralen and zoxamide complex against bacterial wilt of corn

[0044] Drug name and ratio <![CDATA[EC 50 (mg / L)]]> ATI TTI CTC Psoralen 31.7974 100.0000 -- -- zoxamide 4.1855 759.7037 -- -- Psoralen 1: Benzamide 10 2.8114 1131.0166 699.7307 161.6360 Psoralen 1: Benzamide 5 3.6610 868.5441 649.7531 133.6729 Psoralen 1: Benzamide 3 4.3553 730.0852 594.7778 122.7492 Psoralen 1: Benzamide 1 5.2997 599.9849 429.8519 139.5795 Psoralen 3: Benzamide 1 7.6359 416.4198 264.9259 157.1835 Psoralen 5: Benzamide 1 12.4517 255.3659 209.9506 121.6314 Psoralen 10: Benzamide 1 15.5298 204.7509 159.9731 127.9908 Psoralen 20: Benzamide 1 19.7569 160.9433 131.4145 122.4700 Psoralen 40: Benzamide 1 20.4225 155.6979 116.0903 134.1179

[0045] As shown in Table 1, after the active ingredient psoralen is compounded with benzylpyradifur, the co-toxicity coefficient against corn bacterial wilt pathogen is greater than 120 within the mass ratio range of 1-40:10-1, showing a synergistic effect.

[0046] Table 2 Indoor bioactivity test of the combination of psoralen and silthiopyrad against bacterial wilt of corn

[0047] Drug name and ratio <![CDATA[EC 50 (mg / L)]]> ATI TTI CTC Psoralen 31.7974 100.0000 -- -- Silthiovax 13.5106 235.3515 -- -- Psoralen 12: Silothiopyrad 9 11.8726 267.8217 158.0078 169.4991 Psoralen 12: Sithiopyrad 7 13.6349 233.2060 149.8663 155.6093 Psoralen 12: Silothiopyrad 3 18.7450 169.6314 127.0703 133.4941 Psoralen 12: Silthiazolamide 1 23.4185 135.7790 110.4117 122.9752

[0048] As shown in Table 2, after the active ingredient psoralen is compounded with silthiopyrad, the co-toxicity coefficient against corn bacterial wilt pathogen is greater than 120 within the mass ratio range of 12:9-1, showing a synergistic effect.

[0049] In summary, the fungicidal composition of the present invention, which combines psoralen with zoxamide or silthiopyrad, has a cotoxicity coefficient of greater than 120 against bacterial wilt of corn, showing a synergistic effect. Compared with single zoxamide or silthiopyrad, the control efficacy is significantly improved, and the amount of active ingredient used can be reduced, thereby reducing production costs and the amount of pesticide active ingredient residues in the field. This is of great significance to the sustainable development of the ecological environment.

[0050] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A bactericidal composition, characterized in that The active ingredient of the bactericidal composition is prepared by compounding psoralen and zoxamide, and the mass ratio of psoralen to zoxamide is 1-40:10-1.