Bactericidal composition for preventing and treating corn stalk rot and application thereof

Abstract

The invention discloses a bactericidal composition for preventing and treating corn stalk rot and application of the bactericidal composition. The bactericidal composition is formed by compounding hymexazol and benzovindiflupyr according to the weight ratio of (1-20): (1-25). The invention finds that the effect of the mixture of hymexazol and benzovindiflupyr for preventing and treating corn stalk rot caused by infection of pythium and fusarium is obviously higher than that of a single component, the mixture of hymexazol and benzovindiflupyr has a remarkable synergistic effect on pythium and fusarium when the ratio of hymexazol to benzovindiflupyr is (1: 1)-(1: 20) and (1: 1)-(15: 1), the composition has an excellent prevention and treatment effect on corn stalk rot caused by common infection of pythium and fusarium, and the safety to crops and the environment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of pesticides, and in particular to a fungicide composition for preventing and treating corn stalk rot and application thereof. Background Art

[0002] Corn stalk rot, also known as corn stalk rot or corn bacterial wilt, is a soil-borne fungal disease caused by a combination of multiple pathogens. It occurs in corn-producing areas around the world. In the 1950s, the disease broke out in corn-producing areas in the United States, causing a 20-30% reduction in corn yield. There are different reports on the pathogens of corn stalk rot at home and abroad. Foreign research results show that the pathogens causing corn stalk rot are Fusarium spp. and Pythium spp. (Devay et al., 1957; Kommedahl et al., 1978; Koehler, 1960). American scholars believe that the pathogens of corn stalk rot are mainly Fusarium graminearum, Fusarium verticillioides, Diplodia maydis and Fusarium moniliforme (Toman et al., 1993). In Japan, P. aphanidermatum and P. graminicola are the main pathogens. In Brazil, the main pathogen is F. culmorum. In India and other countries, Erwinia is the main pathogen (Cook, 1978; Lal et al., 1984).

[0003] In 1962, the occurrence of corn stalk rot was first reported in my country (Xia Jinhong et al., 1962). The pathogen composition and dominant pathogens of corn stalk rot are different under different planting environments in China. The pathogens in Northeast China are Fusarium and Pythium (Bai Jinkai et al., 1988; Jiang Jingchun et al., 1995; Chen Nan et al., 2015; Zhang Ruiying et al., 1993); the isolation results in Henan, Hebei, Shaanxi, Gansu, Yunnan and other provinces and cities are mainly Fusarium (Yuan Hongxia et al., 2011; Fan Zhiye et al., 2014; Zhang Mingzhi et al., 1988; Shi Jie et al., 2002; Ma Bingyuan et al., 1991; Guo Manku et al., 2011; He Juan et al., 2017); Guangxi reported that Fusarium verticillasteri is the main pathogen of corn stalk rot in the region (Zhang Chaochong et al., 1990). In Beijing and Xinjiang, the main pathogens are Fusarium (Wu Quanan et al., 1997; Yang et al., 1997). Liu Shusen et al. (2019) studied corn stalk rot samples from three provinces (Hebei, Henan, and Shandong) in the main summer corn producing areas of the Huanghuaihai region. The results showed that the main pathogens of stalk rot in the main summer corn producing areas of the Huanghuaihai region were Fusarium complex species and Fusarium.

[0004] Corn stalk rot is a disease that affects the whole growth period. It usually starts to occur during the grain filling period of corn, and the peak of symptoms is from the late milky stage to the waxy stage. Therefore, the pathogen infection period of this disease is very long, and it occurs in all corn producing areas in my country. The incidence rate in general years is 10% to 20%, and it is serious in rainy years, up to 80% or more, and even causes total production. After the disease occurs, it causes lodging, which seriously affects mechanical harvesting. In terms of quality, the pathogen produces harmful substances such as deoxynivalenol, which causes serious harm to humans and livestock. The disease has a tendency to worsen year by year, and has posed a serious threat to my country's corn production and even food security.

[0005] At present, the prevention and control measures for corn stalk rot include selecting disease-resistant varieties, seed coating or seed mixing, root irrigation and pesticide application in the early stage of the disease, etc., but there are very few corn varieties with the characteristics of resistant stalk rot. Therefore, selecting suitable pesticides for coating, seed mixing or root irrigation is the main measure for the prevention and control of corn stalk rot. However, since the occurrence of corn stalk rot in the field is relatively complicated, it is not only greatly affected by the environment, but also Fusarium and Pythium can also cause combined infection and cause the disease. The prevention and control effect of a single agent on the disease caused by combined infection is limited, and long-term use of the same agent is likely to make the pathogen resistant. Therefore, screening new agents for the prevention and control of corn stalk rot is an urgent problem to be solved. Summary of the invention

[0006] In view of the above prior art, the purpose of the present invention is to provide a fungicide composition for preventing and treating corn stalk rot and its application. The present invention combines oxadipazole and benzovindiflupyr as a fungicide composition, which has a significant synergistic effect on the prevention and treatment of corn stalk rot.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a fungicide composition for preventing and treating corn stalk rot, wherein the fungicide composition is compounded by oxadipazole and benzovindiflupyr in a weight ratio of (1-20): (1-25).

[0009] Preferably, the fungicidal composition is prepared by compounding oxadipamide and benzovintriazole in the weight ratio shown in (1) or (2):

[0010] (1) Oxyprolin: Benzotriazole = 1: (1-20);

[0011] (2) Oxyfop-Zacodyl: Benzovinfluazide = (1-15): 1.

[0012] More preferably, the fungicide composition is prepared by compounding oxadipazole and benzotriazole in a weight ratio of 1:1.

[0013] The bactericidal composition of the present invention can achieve a synergistic bactericidal effect on the pathogenic bacteria of corn stalk rot by adjusting the ratio of oxamexazole and benzovinflumazole: when the weight ratio of oxamexazole and benzovinflumazole is 1:(1-20), the bacteriostatic effect of the composition on Pythium aphaniderans is enhanced; when the weight ratio of oxamexazole and benzovinflumazole is (1-15):1, the bacteriostatic effect of the composition on Fusarium graminearum is enhanced; and when the weight ratio of oxamexazole and benzovinflumazole is 1:1, the bacteriostatic effect of the composition on both Pythium aphaniderans and Fusarium graminearum is enhanced.

[0014] The second aspect of the present invention provides the use of the above-mentioned bactericidal composition in at least one of the following (1)-(3):

[0015] (1) Preparing an antibacterial product that simultaneously inhibits Pythium aphanidermatum and Fusarium graminearum;

[0016] (2) Prevent and control corn stem rot;

[0017] (3) Prepare products for preventing and treating corn stalk rot.

[0018] Corn stalk rot is a fungal disease that seriously affects corn yield and quality, and its pathogenic bacteria are mainly Pythium and Fusarium. Methimazole and benzovindiflupyr are two existing fungicides and pesticides, but there is no report on their use for the prevention and treatment of corn stalk rot. The present invention uses methimazole and benzovindiflupyr in combination, and unexpectedly finds that they have a significant synergistic effect on the prevention and treatment of corn stalk rot caused by Pythium and Fusarium alone or in combination.

[0019] The third aspect of the present invention provides an agent for preventing and treating corn stalk rot, wherein the agent contains an effective amount of the above-mentioned fungicide composition.

[0020] Preferably, in the medicament, the weight percentage of the bactericidal composition is 5-80%.

[0021] Furthermore, the medicament also contains pharmaceutical excipients; optional pharmaceutical excipients include but are not limited to: adhesives, emulsifiers, dispersants, wetting agents, stabilizers, etc.

[0022] Furthermore, the medicament can be prepared into various suitable pharmaceutical dosage forms, such as suspensions, granules, powders, aqueous solutions, aqueous emulsions, sustained-release preparations, tablets, and the like.

[0023] A fourth aspect of the present invention provides a method for preventing and treating corn stalk rot, comprising the following steps:

[0024] Before corn sowing or in the early stage of stem base rot, mix the above-mentioned agents with the seeds or spray them on the above-ground parts of the corn plants.

[0025] Beneficial effects of the present invention:

[0026] The present invention first studies and finds that oxamexazole and benzovinflumazole have high inhibitory activity against Pythium and Fusarium that cause corn stem base rot; the effect of oxamexazole and benzovinflumazole mixed for preventing and controlling corn stem base rot is significantly higher than that of a single component, and the ratio of the two has a significant synergistic effect on Pythium in the range of 1:1 to 1:20, and a significant synergistic effect on Fusarium in the range of 1:1 to 15:1. Among them, 1:1 is the best ratio, which has a synergistic effect on the antibacterial effect of Pythium and Fusarium. By using oxamexazole and benzovinflumazole in combination, the dosage of the agent can be reduced, the control effect can be improved, the use cost can be reduced, the resistance of the agent can be delayed, and the safety to crops and the environment can be improved. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0028] As mentioned above, corn stalk rot is a soil-borne disease mainly caused by single or combined infection of Fusarium and Pythium, which is serious and difficult to prevent and control. Screening an antibacterial agent that has excellent inhibitory effects on both Fusarium and Pythium is an urgent problem to be solved.

[0029] In view of this, the present invention investigates the toxicity effects of various fungicides through indoor toxicity determination tests, and screens out oxadipazole, which has higher activity against Pythium aphaniderma than Fusarium graminearum, and benzovinflumizone, which has higher activity against Fusarium graminearum than Pythium aphaniderma. Further, the present invention uses oxadipazole and benzovinflumizone in combination, and surprisingly finds that, compared with a single pesticide, the combination of the two significantly improves the control effect on corn stem base rot, thereby proposing the present invention.

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments. If the specific experimental conditions are not specified in the embodiments, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments and application examples can be obtained through commercial channels unless otherwise specified. Among them:

[0031] The CAS number of oxadiazine is 10004-44-1; the CAS number of benzotriazole is 1072957-71-1.

[0032] The number of Pythium aphanidermatum in the China Agricultural Microbiological Culture Collection is ACCC38064; the number of Fusarium moniliforme in the China Agricultural Microbiological Culture Collection is ACCC38871.

[0033] Example 1: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0034] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 5:1 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0035] Example 2: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0036] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 1:1 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0037] Example 3: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0038] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 1:5 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0039] Example 4: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0040] The mixture of oxadipamide and benzotriazole in a weight ratio of 1:10 is used as a fungicide composition for preventing and controlling corn stalk rot.

[0041] Example 5: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0042] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 1:15 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0043] Example 6: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0044] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 1:20 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0045] Example 7: Preparation of a fungicidal composition for preventing and controlling corn stalk rot

[0046] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 1:25 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0047] Example 8: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0048] The mixture of oxadipazole and benzovintriazole in a weight ratio of 5:1 was used as a fungicide composition for preventing and controlling corn stalk rot.

[0049] Example 9: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0050] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 10:1 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0051] Example 10: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0052] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 15:1 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0053] Example 11: Preparation of a fungicide composition for preventing and controlling corn stalk rot

[0054] The mixture of oxadipamide and benzotriazole was mixed in a weight ratio of 20:1 to prepare a fungicide composition for preventing and controlling corn stalk rot.

[0055] Application Example 1: Indoor toxicity test of a mixture of oxadipazole and benzovindiflupyr against the pathogen of corn stalk rot

[0056] 1. Test pathogens: Pythium aphanidermatum and Fusarium moniliforme. They were used as test strains after continuous transfer culture for two generations in PDA medium at 23±1℃.

[0057] 2. Test methods:

[0058] Refer to the "Pesticide Indoor Bioassay Test Guidelines Fungicides" plate method (NY / T 1156.2-2006) and the combined action determination of fungicide mixtures (NY / T 1156.6-2006).

[0059] Under aseptic operation conditions, use a pipette to add 5.0 mL of different concentrations of drug solution to a pre-calibrated 100 mL sterile conical flask (calibrated volume is 50 mL), then add the culture medium that has been melted and cooled to an appropriate temperature to the conical flask to the calibrated 50 mL mark, shake well, and pour equal amounts into 4 culture dishes. PDA plates containing drugs of corresponding concentrations were prepared. Each concentration treatment was divided into 4 replicates, and the component without active ingredients of the drug was used as a blank control.

[0060] Pre-cultured *Pythium aphanidermatum* and *Fusarium graminearum* were cut into 5-mm-diameter disks with a sterilized borer under aseptic conditions from the edge of the colony. The disks were inoculated onto the center of the drug-containing plate with an inoculator, with the mycelial side facing up. The petri dish lid was covered, and the plate was placed in a biochemical incubator at 23 ± 1°C and 80% relative humidity for dark incubation, and the test results were observed.

[0061] The test was terminated when the colony in the control treatment petri dish grew to 2 / 3 - 4 / 5 of the diameter of the petri dish. The colony diameter (cm) was measured with a ruler. The diameter of each colony was measured vertically once using the cross method, and the average value was taken (subtracting the 5-mm diameter of the disk each time).

[0062] Based on the investigation results, the mycelial growth inhibition rate of each treatment against the test strains was calculated. Then, the DPS data processing software was used to calculate the test results, and the corrected inhibition rate of each treatment was obtained. The toxicity regression equations, EC 50 and EC 90 of the single agent of the test chemical and the mixed agents with different ratios were obtained respectively, as well as the 95% confidence limits. The co-toxicity coefficient (CTC) of different ratios of the two chemicals was calculated to screen out the optimal ratio of the test chemical. And the original data of all replicates of each treatment were recorded.

[0063] The co-toxicity coefficient (CTC) of the compound chemical mixture was calculated according to the Sun Yunpei method. The formula for calculating the co-toxicity coefficient (CTC) is as follows:

[0064] Actual toxicity index (ATI) = (EC 50 of the standard chemical / EC 50 of the test chemical) × 100

[0065] Theoretical toxicity index (TTI) = toxicity index of chemical A × percentage content of chemical A in the mixture + toxicity index of chemical B × percentage content of chemical B in the mixture

[0066] Co-toxicity coefficient (CTC) = (ATI / TTI) × 100

[0067] According to the classification standard of the co-toxicity coefficient (CTC), CTC ≤ 80 indicates antagonism, 80 < CTC < 120 indicates additive effect, and CTC ≥ 120 indicates synergistic effect.

[0068] 3. Test results:

[0069] The test results are shown in Table 1 and Table 2.

[0070] Table 1: Results of in vitro combined toxicity determination of hymexazol and benzovindiflupyr against the pathogen of maize basal rot (*Pythium aphanidermatum*)

[0071]

[0072] Table 2: Results of indoor joint toxicity test of the mixture of oxadipazole and benzovindiflupyr against the pathogen of corn stalk rot (Fusarium graminearum)

[0073]

[0074] From the results in Table 1, it can be seen that oxadipazole and benzovindiflupyr have high activity in inhibiting the mycelial growth of corn stalk rot pathogen (Pythium aphanidermatum). 50 The ratios of the two are 3.0432 mg / L and 40.4628 mg / L respectively. The co-toxicity coefficient (CTC) of the two in the range of 1:1 to 1:20 is greater than 120, and the synergistic effect is significant. They show high activity against the corn stalk rot pathogen (Pythium aphanidermatum). For corn stalk rot caused mainly by Pythium aphanidermatum, the two can be mixed in this ratio range.

[0075] From the results in Table 2, it can be seen that oxadipazole and benzovindiflupyr have high activity in inhibiting the mycelial growth of corn stalk rot pathogen (Fusarium graminearum). 50 The concentrations of the two are 15.0330mg / L and 5.0100mg / L respectively. The co-toxicity coefficient (CTC) of the two in the range of 1:1 to 15:1 is greater than 120, and the synergistic effect is significant. They show high activity against the pathogen of corn stalk rot (Fusarium graminearum). For corn stalk rot mainly caused by Fusarium, this ratio range can be used to mix the two.

[0076] For corn stalk rot caused by co-infection of Pythium and Fusarium, a 1:1 mixture of oxadipamide and benzotriazole can be used.

[0077] In summary, the fungicidal composition of the present invention, which is a combination of oxadipamide and benzovindiflupyr, has a significant synergistic effect, can reduce the dosage of the agent, improve the effect of preventing and controlling corn stalk rot, reduce the cost of use, delay the resistance of the agent, and improve the safety to crops and the environment.

[0078] Application example 2: Field control effectiveness test

[0079] The test agents of oxadipamide, benzovintriazole, and the three selected mixtures were formulated according to the dosage design in Table 3, and an appropriate amount of film-forming agent was added to coat the corn seeds. The coated seeds were sown on the same day. At the same time as sowing, the aphanidermatum and graminearum Fusarium cultured with sterilized corn kernels were inoculated into the corn sowing furrow, and each corn plant was inoculated with one corn kernel with aphanidermatum and graminearum Fusarium. The treatment without coating but inoculation was used as a blank control. The incidence of corn plants in the field was investigated during the milky stage of corn, and the control effect was calculated.

[0080]

[0081] Where: CK1--disease index of blank control area after application;

[0082] PT1--Disease index after application of pesticide in the treatment area.

[0083] Table 3: Control results of corn stalk rot by seed coating with a mixture of oxadipazole and benzovindiflupyr

[0084]

[0085] The above results show that the combined use of oxadipamide and benzopyrene has the effect of reducing the amount and increasing the efficiency for field control of corn stalk rot.

[0086] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fungicidal composition for preventing and treating corn stalk rot, characterized in that: The bactericidal composition is prepared by compounding oxadipazole and benzovintriazole in a weight ratio of (1-20): (1-25).

2. The bactericidal composition according to claim 1, characterized in that The bactericidal composition is prepared by compounding oxadipazole and benzovintriazole in the following weight ratio as shown in (1) or (2): (1) Oxyprolin: Benzotriazole = 1: (1-20); (2) Oxyfop-Zacodyl: Benzovinfluazide = (1-15):

1.

3. The bactericidal composition according to claim 1 or 2, characterized in that The bactericidal composition is prepared by compounding oxadipazole and benzovintriazole in a weight ratio of 1:

1.

4. Use of the bactericidal composition according to any one of claims 1 to 3 in at least one of the following (1) to (3): (1) Preparing an antibacterial product that simultaneously inhibits Pythium aphanidermatum and Fusarium graminearum; (2) Prevent and control corn stem rot; (3) Prepare products for preventing and treating corn stalk rot.

5. A medicament for preventing and treating corn stalk rot, characterized in that: The medicament contains an effective amount of the bactericidal composition according to any one of claims 1 to 3.

6. A method for preventing and treating corn stalk rot, characterized in that: The following steps are involved: Before corn is sown or at the early stage of stem base rot, the agent of claim 5 is mixed with seeds or sprayed on the above-ground part of corn plants.

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