Application of SYP-Z048 in resisting cotton verticillium wilt and fusarium wilt and prevention and treatment method

Abstract

The invention discloses application of SYP-Z048 in resisting cotton verticillium wilt and fusarium wilt and a prevention and treatment method. According to the invention, SYP-Z048 is taken as a unique active component, and indoor and field bacteriostasis tests prove that SYP-Z048 can inhibit the growth of verticillium dahliae and fusarium oxysporum, reduce the disease index of cotton verticillium wilt and fusarium oxysporum, reduce the influence of verticillium wilt and fusarium oxysporum on the agronomic traits of cotton plants in the boll stage, and improve the quality of cotton boll stage plants. The method is used for preventing and treating cotton verticillium wilt and fusarium wilt, and is simple and effective.

Description

Technical Field

[0001] The present invention belongs to the field of pesticides, and particularly relates to the application of picoxystrobin in the control of cotton Verticillium wilt and Fusarium wilt and the control method. Background Art

[0002] Cotton Fusarium wilt and Verticillium wilt are important diseases in cotton production, especially Verticillium wilt. Both Fusarium wilt and Verticillium wilt are systemic infection diseases, known as the "cancer" of cotton, often causing serious yield reduction or even crop failure. Cotton Verticillium wilt is a world-wide disease with serious harm, characterized by wide distribution, heavy damage, broad host range, multiple transmission routes, and long survival time. There are 5 strains of cotton Verticillium wilt, among which Verticillium dahliae and Verticillium albo-atrum cause vascular wilt worldwide, and Verticillium dahliae is the main pathogen of cotton Verticillium wilt in the main cotton-producing areas of China (Zhang Maolin, Xia Rizhao, Liao Xiaolan. Research progress on the control methods of cotton Verticillium wilt [J]. Modern Agricultural Science and Technology, 2014, (07): 129-131.). At present, there is no chemical agent with a specific control effect on cotton Verticillium wilt. The reported control agents for cotton Verticillium wilt include: carbendazim, potassium permanganate, prochloraz, and mepiquat chloride, etc. Cotton Fusarium wilt is caused by cotton Fusarium wilt disease, and is one of the devastating cotton diseases with serious harm. The main chemical control agents for cotton Fusarium wilt and Verticillium wilt are hymexazol, carbendazim, thiophanate-methyl, tebuconazole, and cotton wilt cleaner, etc. However, Xinjiang is the core cotton-producing area in China, but most of the cultivated land is soil infected with Fusarium wilt and Verticillium wilt, and cotton Fusarium wilt and Verticillium wilt coexist in cotton fields all year round, and crop rotation is difficult, resulting in serious damage to cotton quality, yield, and economy (Liu et al ., 2023) (LIU H, WU B, ZHANG J, et al. Influence of interlayer soil on the water infiltration characteristics of heavy saline-alkali soil in southern Xinjiang [J]. Agronomy, 2023, 13(7): 1912.). Therefore, chemical agents for the control of cotton Verticillium wilt and Fusarium wilt need to be further developed.

[0003] Picoxystrobin, its chemical name is N-methyl-3-(4-chloro)phenyl-5-methyl-5-pyridin-3-yl-isoxazoline. The chemical structural formula is as follows: .

[0004] This agent is a highly effective and broad-spectrum agricultural fungicide invented by Shenyang Research Institute of Chemical Industry in 1997. It has a novel structure and a unique action mechanism, featuring high efficiency, broad spectrum and good safety. Its technical material (content ≥ 90%) is a brownish-yellow viscous oily substance with some solid precipitates. There are cis- and trans-isomers (Z-form, E-form) in the structure of picoxystrobin, and the technical material is a mixture of Z-form and E-form. There is no significant difference in the biological activity between Z-form and E-form, and they can convert into each other at normal temperature. Melting range: 51 - 65 °C; vapor pressure: 0.48 mPa (20 °C); soluble in acetone, chloroform, ethyl acetate and ether, slightly soluble in petroleum ether, insoluble in water. Stable to acids and bases at normal temperature. Stable in water, sunlight or light. Decomposes at high temperature, and the obvious decomposition temperature ≥ 180 °C. There has been a commercial agent, 25% Junsqi (picoxystrobin) EC, on the market. Patents have been applied for and obtained in China, the United States, Europe, etc. (China Patent CN1280767A, US Patent U127783P, European Patent EP1035122). It has high application value and good application prospects. It has high bactericidal activity, has systemic conduction, has dual activities of protection and treatment, and has excellent control effect on Botrytis cinerea; it can control Botrytis cinerea of tomato, cucumber, strawberry, Chinese chive, tomato leaf mold, apple blotch. Since picoxystrobin came out, many scholars have studied it. Guan Yiming et al. found that the EC50 value of 25% picoxystrobin EC against Alternaria panax was 0.3290 μg / mL, and the field control effect of 2000-fold solution of this agent reached 86.5%. However, the EC50 value of 84% picoxystrobin EC against Ceratocystis fimbriata was 0.1000 μg / mL. Song Weiguo et al. pointed out that 25% picoxystrobin EC can replace carbendazim and thiophanate-methyl at recommended doses for controlling Botrytis cinerea, thus reducing the potential hazards caused by the use of these two agents (excessive use of these two agents will increase the residues in environmental elements and agricultural products). Liu Chunyan et al. found that the field control effects of 25% picoxystrobin on Botrytis cinerea and tomato leaf mold were 85.58 - 89.79% and 83.87 - 89.14% respectively, both superior to the control effects of currently commonly used agents. Currently, there is no relevant literature report on using picoxystrobin to control Verticillium wilt and Fusarium wilt of cotton. Summary of the Invention

[0005] The object of the present invention is to provide the application and control method of picoxystrobin in resisting Verticillium wilt and Fusarium wilt of cotton. Picoxystrobin can inhibit the growth of Verticillium dahliae and Fusarium oxysporum f. sp. vasinfectum, and can be used for controlling Verticillium wilt and Fusarium wilt of cotton.

[0006] In the first aspect, the present invention provides the application of picoxystrobin or a composition containing picoxystrobin in inhibiting the pathogen of Verticillium wilt of cotton.

[0007] In the present invention, the term "composition containing picoxystrobin" may be a picoxystrobin preparation with picoxystrobin as the active ingredient, or a composition in which picoxystrobin is compounded with other active ingredients, or a preparation with such a compounded composition as the active ingredient. The said preparation includes the active ingredient and auxiliaries acceptable in pesticide preparations, including any dosage forms such as aqueous suspension concentrate, dispersible oil suspension concentrate, emulsion in water, microcapsule formulation, microemulsion, wettable powder, soluble powder, water dispersible granule, seed treatment dispersant, suspension seed coating agent, or seed treatment microcapsule suspension, etc. As an example, the picoxystrobin preparation is 25% picoxystrobin emulsion in water.

[0008] In the above application, the pathogen causing cotton verticillium wilt is Verticillium dahliae, preferably physiological race V991.

[0009] Specifically, the inhibition of the pathogen causing cotton verticillium wilt is manifested as the inhibition of the mycelial growth of the pathogen causing cotton verticillium wilt.

[0010] In the second aspect, the present invention provides the application of picoxystrobin or a composition containing picoxystrobin in any one of the following: A1) Controlling cotton verticillium wilt; A2) Improving the agronomic traits of cotton plants at the boll stage with cotton verticillium wilt.

[0011] In the above application, the pathogen causing cotton verticillium wilt is Verticillium dahliae, preferably physiological race V991; The agronomic traits of the cotton plants at the boll stage include one or more of the total number of bolls, the number of effective bolls, the number of fruiting branches, the boll shedding rate, the plant height, and the height of the first fruiting branch.

[0012] In the third aspect, the present invention provides a method for controlling cotton verticillium wilt, including the step of applying picoxystrobin or a composition containing picoxystrobin during the cotton seedling stage.

[0013] In the above method for controlling cotton fusarium wilt, the pathogen causing cotton verticillium wilt is Verticillium dahliae, preferably physiological race V991; As an example, the cotton is cotton with both cotton verticillium wilt and cotton fusarium wilt; As an example, the composition of picoxystrobin is 25% picoxystrobin emulsion in water, and the application method is to irrigate its aqueous solution. The concentration after dilution of 25% picoxystrobin emulsion in water in the aqueous solution is 0.85 - 1.25 ml / L; calculated by picoxystrobin, the irrigation concentration is 208.3 ppm.

[0014] In the fourth aspect, the present invention provides the application of picoxystrobin or a composition containing picoxystrobin in any one of the following: B1) Controlling cotton verticillium wilt and cotton fusarium wilt simultaneously; B2) Improve the agronomic traits of cotton plants during the boll stage with both Verticillium wilt and Fusarium wilt of cotton.

[0015] In the above application, the pathogenic bacterium of the Verticillium wilt of cotton is Verticillium dahliae, preferably physiological race V991; The pathogenic bacterium of the Fusarium wilt of cotton is Fusarium oxysporum f. sp. vasinfectum, preferably physiological race 7; The agronomic traits of the cotton plants during the boll stage include one or more of the total number of bolls, the number of effective bolls, the number of fruiting branches, the boll shedding rate, the plant height, and the height of the first fruiting branch.

[0016] In the fifth aspect, the present invention provides a method for controlling Verticillium wilt and Fusarium wilt of cotton, including the step of applying picoxystrobin or a composition containing picoxystrobin during the cotton seedling stage.

[0017] In the above method for controlling Verticillium wilt and Fusarium wilt of cotton, the pathogenic bacterium of the Verticillium wilt of cotton is Verticillium dahliae, preferably physiological race V991; The pathogenic bacterium of the Fusarium wilt of cotton is Fusarium oxysporum f. sp. vasinfectum, preferably physiological race 7; As an example, the composition of picoxystrobin is 25% picoxystrobin aqueous emulsion, and the application method is to irrigate its aqueous solution. The concentration of the diluted 25% picoxystrobin aqueous emulsion in the aqueous solution is 0.85 - 1.25 ml / L; calculated by picoxystrobin, the irrigation concentration is 208.3 ppm.

[0018] In the sixth aspect, the present invention provides the application of picoxystrobin or a composition containing picoxystrobin in inhibiting the pathogenic bacterium of Fusarium wilt of cotton.

[0019] In the above application, the pathogenic bacterium of the Fusarium wilt of cotton is Fusarium oxysporum f. sp. vasinfectum, preferably physiological race 7.

[0020] Specifically, the inhibition of the pathogenic bacterium of Fusarium wilt of cotton is manifested as inhibiting the mycelial growth of the pathogenic bacterium of Fusarium wilt of cotton.

[0021] In the seventh aspect, the present invention provides the application of picoxystrobin or a composition containing picoxystrobin in any one of the following: C1) Controlling Fusarium wilt of cotton; C2) Improving the agronomic traits of cotton plants during the boll stage with Fusarium wilt of cotton.

[0022] In the above application, the pathogenic bacterium of the Fusarium wilt of cotton is Fusarium oxysporum f. sp. vasinfectum, preferably physiological race 7; The agronomic traits of the cotton plants during the boll stage include one or more of the total number of bolls, the number of effective bolls, the number of fruiting branches, the boll shedding rate, the plant height, and the height of the first fruiting branch.

[0023] In an eighth aspect, a method for controlling cotton fusarium wilt includes the step of applying picoxystrobin or a composition containing picoxystrobin during the seedling stage of cotton.

[0024] In the above method for controlling cotton fusarium wilt, the pathogenic bacterium of cotton fusarium wilt is Fusarium oxysporum f. sp. vasinfectum, preferably physiological race 7. As an example, the cotton is cotton that simultaneously has verticillium wilt and fusarium wilt. As an example, the composition of picoxystrobin is 25% picoxystrobin aqueous emulsion, and the application method is to irrigate its aqueous solution. The concentration after dilution of 25% picoxystrobin aqueous emulsion in the aqueous solution is 0.85 - 1.25 ml / L; calculated by picoxystrobin, the irrigation concentration is 208.3 ppm.

[0025] The present invention has the following beneficial effects: The present invention uses picoxystrobin as the only active ingredient. It is confirmed by indoor and field antibacterial tests that picoxystrobin can inhibit the growth of Verticillium dahliae and Fusarium oxysporum f. sp. vasinfectum, reduce the disease index of cotton verticillium wilt and fusarium wilt, and reduce the influence of verticillium wilt and fusarium wilt on the agronomic traits of cotton plants during the boll stage. It is used to control cotton verticillium wilt and fusarium wilt, and the control method is simple and effective. Description of the Drawings

[0026] Figure 1 It is the plate inhibition of fusarium wilt bacteria by picoxystrobin aqueous emulsion in Example 1 of the present invention; Note: A: mixture of water and fusarium wilt bacteria; B: mixture of 2.7 ul / ml and fusarium wilt bacteria (drug mixing method); C: mixture of 4 ul / ml and fusarium wilt bacteria (drug mixing method); D: 27 ul / ml + fusarium wilt bacteria (drug mixing method); E: 40 ul / ml + fusarium wilt bacteria (drug mixing method); F: smear 100 ul of water (drug smearing method); G: smear 2.7 ul / ml of 25% picoxystrobin aqueous emulsion (drug smearing method); H: smear 4 ul / ml of 25% picoxystrobin aqueous emulsion; I: smear 27 ul / ml of 25% picoxystrobin aqueous emulsion (drug smearing method); J: smear 40 ul / ml of 25% picoxystrobin aqueous emulsion (drug smearing method).

[0027] Figure 2 It is the plate inhibition of fusarium wilt bacteria by picoxystrobin aqueous emulsion in Example 2 of the present invention (filter paper method); Note: a, c and e: sterile distilled water is dropped on the filter paper; b: 2.7 ul / ml of 25% picoxystrobin aqueous emulsion is dropped; d: 4 ul / ml of 25% picoxystrobin aqueous emulsion is dropped; f: the original solution of 25% picoxystrobin aqueous emulsion is dropped.

[0028] Figure 3For the plate inhibition of Verticillium dahliae by the pyrisoxazole aqueous emulsion in Example 3 of the present invention; Note: A: mixture of water and Verticillium dahliae; B: mixture of 25% pyrisoxazole aqueous emulsion at 2.7 ul / ml and Verticillium dahliae; C: mixture of 25% pyrisoxazole aqueous emulsion at 4 ul / ml and Verticillium dahliae; D: mixture of 25% pyrisoxazole aqueous emulsion at 27 ul / ml and Verticillium dahliae; E: mixture of 25% pyrisoxazole aqueous emulsion at 40 ul / ml and Verticillium dahliae; F: mixture of the original solution of 25% pyrisoxazole aqueous emulsion and Verticillium dahliae.

[0029] Figure 4 For the plate inhibition of Verticillium dahliae by the pyrisoxazole aqueous emulsion in Example 4 of the present invention (filter paper method); Note: a, c, e, g and i: sterile distilled water was dropped on the filter paper; b: 25% pyrisoxazole aqueous emulsion at 2.7 ul / ml; d: 25% pyrisoxazole aqueous emulsion at 4 ul / ml; f: 25% pyrisoxazole aqueous emulsion at 27 ul / ml; h: 25% pyrisoxazole aqueous emulsion at 40 ul / ml; j: original solution of 25% pyrisoxazole aqueous emulsion.

[0030] Figure 5 For the phenotype of the field control effect of pyrisoxazole solution by root irrigation on cotton Verticillium wilt in Example 5 of the present invention; Note: A: control; B: test group (208.3 ppm pyrisoxazole aqueous emulsion).

[0031] Figure 6 Disease index of the field control effect of pyrisoxazole solution by root irrigation on cotton Verticillium wilt in Example 5 of the present invention; Note: Disease index is the disease index, and CK is the control test group.

[0032] Figure 7 Correlation between disease index and agronomic trait indicators in Example 5 of the present invention; Note: DI: disease index; BN: total number of bolls; EBN: effective number of bolls; FBN: number of fruiting branches; BBAR: rate of boll and bud abscission; PH: plant height; HFNFB: height of the first fruiting branch; "-": negative correlation; "+": positive correlation; the size of the blue and red circles: represents the strength of the correlation, the larger the circle, the stronger the correlation, otherwise the correlation is weak. Detailed implementation manners

[0033] The present invention will be further described in detail below in conjunction with the specific implementation manners. The provided examples are only for clarifying the present invention, rather than limiting the scope of the present invention. The following provided examples can be used as a guide for those of ordinary skill in the art to make further improvements, and do not limit the present invention in any way.

[0034] The methods used in the following examples are all conventional methods unless otherwise specified, and are carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0035] The cotton variety used in the experiments in the following examples is the cultivated variety (Tahe No. 2), which is disclosed in the literature "Li Qin, Li Daikuo, Xu Anyang, et al. Breeding and Cultivation Techniques of New Cotton Variety Tahe No. 2 [J]. China Cotton, 2020, 47(10): 30+41." The fusarium wilt pathogen strain used in the experiment is Fusarium oxysporum f. sp. vasinfectum, physiological race 7, which is disclosed in the literature "Feng Jie, Chen Qi. General Situation of Basic Research on Cotton Fusarium Wilt in China [J]. Acta Gossypii Sinica, 1994(02): 65-69."; the Verticillium wilt pathogen strain used is Verticillium dahliae, physiological race V991, which is disclosed in the literature "Zhang Xin Z X, Jian GuiLiang J GL, Lin Ling L L, et al. Detection of defoliating pathotype of Verticillium dahliae in soil by nested-PCR [J]. 2011."; these Verticillium and fusarium wilt pathogen strains are provided by the Key Laboratory of Cotton of Xinjiang Agricultural University.

[0036] The field disease nursery is a natural disease nursery with mixed Verticillium and fusarium wilt, and the cotton field has been diseased all year round and the disease is serious.

[0037] The 25% picoxystrobin aqueous emulsion is purchased from Sinochem Crop Protection Co., Ltd.

[0038] Example 1 Plate Inhibition Experiment of Picoxystrobin Aqueous Emulsion against Fusarium Wilt Pathogen Fermentation of fusarium wilt pathogen strain: Weigh 17.5 g of Czapek's liquid medium (purchased from Haibo Biotech) and dissolve it in 500 ml of distilled water, and sterilize it at 115-116 °C for 30 min. After cooling, place it in a laminar flow hood, and pick 1 piece of fusarium wilt pathogen block on a PDA solid medium (20 mL) into the sterilized Czapek's liquid medium, and culture it in a constant temperature shaker at 28 °C and 120 rpm / min for 3-5 d. Obtain a bacterial suspension, and after vacuum filtration through double-layer filter paper, prepare a spore suspension with a concentration of 1x10 2 cfu / ml for standby. 7

[0039] Take 2.7, 4, 27, and 40 μl of 25% picoxystrobin aqueous emulsion, dissolve them in 1 ml of water, and prepare picoxystrobin aqueous emulsion solutions with concentrations of 2.7 μl / ml, 4 μl / ml, 27 μl / ml, and 40 μl / ml. (1) Agent mixing method: Mix the 4 prepared concentrations (2.7 μl / ml, 4 μl / ml, 27 μl / ml, and 40 μl / ml) with the same amount of Fusarium oxysporum f. sp. vasinfectum (1 x 10 7 CFU / ml) in a 1:1 ratio to set up the experimental groups, and mix sterile water with the same amount of Fusarium oxysporum f. sp. vasinfectum in a 1:1 ratio to set up the control group. After placing for 24 hours, pipette 20 μl of the mixed solution and drop it in the center of a PDA solid medium, then invert and culture it in an incubator at 28°C. Observe after 7 days. The results of the antibacterial test show that chalcone can inhibit the growth of Fusarium oxysporum f. sp. vasinfectum. (2) Agent coating method: Pipette 100 μl of picoxystrobin aqueous emulsion solutions with different concentrations (0 μl / ml, 2.7 μl / ml, 4 μl / ml, 27 μl / ml, and 40 μl / ml) and evenly coat them on the PDA solid medium. After the PDA solid medium completely absorbs the drug, pipette 20 μl of Fusarium oxysporum f. sp. vasinfectum (1 x 10 7 CFU / ml) and drop it in the center of the treated PDA solid medium, then invert and culture it in an incubator at 28°C. Observe after 7 days. Picoxystrobin has a certain inhibitory effect on Fusarium oxysporum f. sp. vasinfectum (race 7) ( Figure 1 ). The inhibition rate (%) = (colony diameter of CK - colony diameter of treatment) / colony diameter of CK. According to the agent mixing method, it can be observed that the colony diameter of the control group A in Figure A is 9 cm, the colony diameters of the experimental groups B and C in Figures B and C are both 4.5 cm, and the inhibition rates are both 50%. The absence of colonies in the experimental groups D and F in Figures D and F indicates that the sterilization rate is 100%. According to the agent coating method, it can be observed that the colony diameter of the control group F in Figure F is 9 cm, the colony diameters of the experimental groups G, H, I, and J in Figures G, H, I, and J are 6 cm, 3.5 cm, 1.9 cm, and 1.7 cm respectively, and the inhibition rates are 33.3%, 61.1%, 78.9%, and 81.1% respectively.

[0040] Example 2 Plate inhibition experiment of picoxystrobin aqueous emulsion against Fusarium oxysporum f. sp. vasinfectum (filter paper method) Prepare a plate of Fusarium oxysporum f. sp. vasinfectum: Pipette 100 μl of Fusarium oxysporum f. sp. vasinfectum of cotton (spore concentration of 1 x 10 7Drop the spore suspension (at a concentration of Figure 2 cfu / mL) onto the PDA solid medium (20 mL). Use a spreading rod to evenly spread the spore suspension on the PDA solid medium (20 mL) until the PDA solid medium (20 mL) completely absorbs the spore suspension without any flowing liquid, indicating the completion of the preparation of the pathogen plate. After the plate is air-dried, place 2 sterile filter papers with a diameter of 10 mm. Drop sterile distilled water on one filter paper, and drop 20 μL each of the original solution of picoxystrobin aqueous emulsion with concentrations of 2.7 μL / mL, 4 μL / mL, and 25% on the other filter paper. Incubate the plate upside down in an incubator at 28 °C and observe after 7 days. The results show that the sterile filter papers (A-a, B-c, and C-e) with clear water control drops are covered with pathogens, while the sterile filter papers (A-b, B-d, and C-f) with picoxystrobin aqueous emulsion solution drops have no pathogens growing on them, indicating that the picoxystrobin aqueous emulsion solution can inhibit the growth of Figure 2 Verticillium wilt pathogens of cotton. The inhibition rate = (diameter of the inhibition zone - diameter of the Oxford cup / diameter of the filter paper) / diameter of the inhibition zone × 100%. For Figure A-b, the diameter of the inhibition zone is approximately 4.4 cm, and the inhibition rate is approximately 77.3%. For Figures B-d and C-f, the diameter of the inhibition zone is approximately 4.6 cm, and the inhibition rate is approximately 78.3% (

[0041] Example 3 Plate inhibition experiment of picoxystrobin aqueous emulsion against Verticillium wilt pathogens Fermentation of Verticillium wilt pathogen strains: Weigh 17.5 g of Czapek's liquid medium (purchased from Haibo Biology) and dissolve it in 500 mL of distilled water. Autoclave at 115 - 116 °C for 30 min. After cooling, place it in a laminar flow hood, pick out 1 block of Verticillium wilt pathogen block on the PDA solid medium (20 mL) and transfer it to the sterilized Czapek's liquid medium. Incubate in a constant temperature shaker at 28 °C and 120 rpm / min for 5 - 7 d. Obtain the bacterial suspension, and after vacuum filtration through double-layer filter paper, prepare a spore suspension with a concentration of 1×10 2 cfu / mL for standby. 7

[0042] Take 2.7, 4, 27, and 40 μL of 25% picoxystrobin aqueous emulsion and dissolve them in 1 mL of water to prepare picoxystrobin aqueous emulsion solutions with concentrations of 2.7 μL / mL, 4 μL / mL, 27 μL / mL, and 40 μL / mL. (1) Mix the prepared picoxystrobin aqueous emulsion solutions with concentrations of 2.7 μL / mL, 4 μL / mL, 27 μL / mL, 40 μL / mL, and the undiluted original concentration with the same amount of Verticillium wilt pathogens (1×10 7 ​Mix them at a ratio of 1:1 to set up the experimental group, and mix sterile water with the same amount of Verticillium dahliae at a ratio of 1:1 to set up the control group. After standing for 24 hours respectively, aspirate 20 μl of the mixed solution and drop it onto the center of the PDA solid medium, then invert and culture it in an incubator at 28 °C. Observe after 14 days. The results of the antibacterial test show that the picoxystrobin aqueous emulsion solution can inhibit the growth of Verticillium dahliae in cotton ( Figure 3 ). The calculation method of the antibacterial rate is the same as that in Example 1. Among them, the colony diameter in Figure A is 6.3 cm, the colony diameter in Figure B is 1.4 cm, the antibacterial rate is 77.7%, and the fact that there is no colony growth in Figures C, D, E, and F indicates that the sterilization rate is 100%.

[0043] Example 4: Plate inhibition experiment of picoxystrobin aqueous emulsion against Verticillium dahliae (filter paper method) Prepare a Verticillium dahliae pathogen plate: Drop 100 μl of a suspension of Verticillium dahliae (spore concentration is 1×10 7 CFU / mL) on the PDA solid medium (20 mL), and use a spreader to evenly smear the spore suspension on the PDA solid medium (20 mL) until the PDA solid medium (20 mL) completely absorbs the spore suspension and there is no flowing liquid, that is, the preparation of the pathogen plate is completed. After the plate is dried, place 2 sterile filter papers with a diameter of 10 mm. Drop 20 μL of sterile distilled water on one filter paper, and drop 20 μL of picoxystrobin aqueous emulsion solutions with concentrations of 2.7 μl / ml, 4 μl / ml, 27 μl / ml, 40 μl / ml and the undiluted original concentration on the other filter paper respectively. Invert and culture it in an incubator at 28 °C. Observe after 21 days. The results show that the sterile filter papers (A-a, B-c, C-e, D-g and E-i) with clear water control drops are covered with bacteria, while the sterile filter papers (A-b, B-d, C-f, D-h and E-j) with picoxystrobin aqueous emulsion solution drops have no bacteria growth, and an antibacterial circle is produced, indicating that the picoxystrobin aqueous emulsion solution can inhibit the growth of Verticillium dahliae in cotton ( Figure 4 ). The calculation method of the antibacterial rate is the same as that in Example 2. The antibacterial circle diameters of A-b, B-d, C-f, D-h, and E-j are approximately 4.6 cm, 4.7 cm, 5.5 cm, 5.8 cm and 6.2 cm respectively, and the antibacterial rates are approximately 78.3%, 78.7%, 81.8%, 82.8% and 83.9% respectively.

[0044] Example 5: Field control effect experiment of picoxystrobin solution by root irrigation on cotton verticillium wilt and fusarium wilt This experiment was conducted in the Changji experimental field in 2024 (where Verticillium wilt and Fusarium wilt occur frequently and severely), using the conventional field variety (Tahe No. 2) as the experimental material. Three membranes were selected for the experiment at the seedling stage (i.e., 3 replicates, with about 120 cotton plants per treatment). The cotton material irrigated with clear water was used as the control group (CK), and the cotton material irrigated with 208.3 ppm of picoxystrobin emulsion (25% picoxystrobin emulsion diluted 1200 times) was used as the experimental group. 30 cotton seedlings were randomly selected from each replicate for investigation.

[0045] Refer to the method disclosed in the literature "Peng Zhen, Jiao Guangjing, Jin Yilong, et al. Preliminary report on the experiment and demonstration of Mianweike in controlling Verticillium wilt and Fusarium wilt of cotton [J]. Bulletin of Agricultural Science and Technology, 2016, (05): 92-94." to investigate the Fusarium wilt and Verticillium wilt of the control group and the experimental group, and determine the grading and calculate the disease index according to the following standards and formulas: The disease grading standard for Verticillium wilt and Fusarium wilt of cotton is as follows: Grade 0, disease-free; Grade 1, the number of diseased leaves is less than 10% of the total number of leaves; Grade 2, the number of diseased leaves accounts for 10% - 25% of the total number of leaves; Grade 3, the number of diseased leaves accounts for 25% - 50% of the total number of leaves; Grade 4: The number of diseased leaves accounts for more than 50% of the total number of leaves, and the leaves, buds and bolls fall off until the plants die.

[0046] Disease index = [Σ (number of diseased plants at each level × relative grade value) / (total number of plants investigated × 4)] × 100.

[0047] The disease index and prevalence rate of different treatments are shown in the following table.

[0048] Table 1. Disease index and prevalence rate of different treatments

[0049] The cotton material irrigated with clear water was used as the control group (CK), and the cotton material irrigated with 208.3 ppm of picoxystrobin emulsion (25% picoxystrobin emulsion diluted 1200 times) was used as the experimental group. Irrigation was carried out when the cotton had grown 6 - 7 true leaves, and a total of 2 irrigations were carried out, with an interval of 15 days. Each treatment was irrigated with 12 L each time.

[0050] When the cotton was in the boll stage, observe the plant phenotype and measure the agronomic traits. There were 3 replicates for both the control group and the experimental group. 10 plants were randomly selected from each replicate to measure the total number of bolls, the number of effective bolls, the number of fruiting branches, and the boll shedding rate. At the same time, 5 plants were randomly selected to measure the plant height and the height of the first fruiting branch. The results are shown in the following table.

[0051] Table 2. Agronomic traits of different treatments

[0052] The phenotypic observation of cotton plants is as follows Figure 5 shown. Compared with the control, the cotton materials in the experimental group had stronger plants, and less leaf and bud boll abscission (Table 2). According to the investigation of the disease index in the cotton field, it was found that the disease index of the cotton materials in the experimental group was significantly lower than that of the control (Table 1 and Figure 6 ), indicating that irrigating with 208.3 ppm of picoxystrobin emulsion in water could inhibit the invasion of Verticillium wilt and Fusarium wilt pathogens on cotton. Through the correlation analysis of the disease index and agronomic trait indicators, it was found that the disease index was negatively correlated with the total boll number and the effective boll number, and significantly positively correlated with the bud boll abscission rate. This shows that the greater the disease index, the fewer the total boll number and the effective boll number, and the higher the bud boll abscission rate ( Figure 7 ).

[0053] The above has described the present invention in detail. For those skilled in the art, within the scope of not departing from the purpose and spirit of the present invention, the present invention can be implemented within a relatively wide range under equivalent parameters, concentrations and conditions. Although specific embodiments of the present invention are given, it should be understood that the present invention can be further improved. In short, according to the principle of the present invention, this application intends to cover any change, use or improvement of the present invention, including changes made with conventional techniques known in the art that are outside the scope disclosed in this application.

Claims

1. Application of picoxystrobin or a composition containing picoxystrobin in inhibiting the pathogen causing Verticillium wilt of cotton.

2. The application according to claim 1, wherein: The pathogen causing Verticillium wilt of cotton is Verticillium dahliae, preferably physiological race V991.

3. Application of picoxystrobin or a composition containing picoxystrobin in any of the following: A1) Controlling Verticillium wilt of cotton; A2) Improving the agronomic traits of cotton plants at the boll stage with Verticillium wilt.

4. A method for controlling Verticillium wilt of cotton, comprising the step of applying picoxystrobin or a composition containing picoxystrobin at the seedling stage of cotton.

5. Application of picoxystrobin or a composition containing picoxystrobin in any of the following: B1) Simultaneously controlling Verticillium wilt and Fusarium wilt of cotton; B2) Improving the agronomic traits of cotton plants at the boll stage with both Verticillium wilt and Fusarium wilt.

6. A method for controlling Verticillium wilt and Fusarium wilt of cotton, comprising the step of applying picoxystrobin or a composition containing picoxystrobin at the seedling stage of cotton.

7. Application of picoxystrobin or a composition containing picoxystrobin in inhibiting the pathogen causing Fusarium wilt of cotton.

8. The application according to claim 7, wherein: The pathogen causing Fusarium wilt of cotton is Fusarium oxysporum f. sp. vasinfectum, preferably physiological race 7.

9. Application of picoxystrobin or a composition containing picoxystrobin in any of the following: C1) Controlling Fusarium wilt of cotton; C2) Improving the agronomic traits of cotton plants at the boll stage with Fusarium wilt.

10. A method for controlling Fusarium wilt of cotton, comprising the step of applying picoxystrobin or a composition containing picoxystrobin at the seedling stage of cotton.

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