Broad-spectrum plant source bactericide and application thereof

Abstract

The present application belongs to the technical field of plant disease and pest control, and particularly relates to a broad-spectrum plant source fungicide suitable for economic forest plants such as polygonatum sibiricum and camellia oleifera and application thereof. The present application verifies through experiments that plant sphingosine has different degrees of inhibitory effect on different plant pathogens, and the inhibition rate increases with the increase of the treatment concentration, showing an obvious dose-effect relationship, and further indicating that the action mechanism has broad spectrum, can effectively prevent and control stem rot, leaf spot and the like caused by fusarium oxysporum, fusarium solani, phoma capitalensis, botryosphaeria dothidea and the like, significantly reduces the pathogen damage level, improves the oxidation resistance and disease resistance of plants, promotes the growth of plants, and improves the crop yield and quality. Compared with traditional chemical pesticides, plant sphingosine as a plant source agent has the outstanding characteristics of low residue, easy degradation and environmental friendliness, and fits the development direction of modern agricultural green prevention and control, and can be used as an effective alternative to chemical pesticides.

Description

Technical Field

[0001] This invention belongs to the field of plant disease and pest control technology, specifically relating to a broad-spectrum plant-derived fungicide applicable to economic forest plants such as Polygonatum sibiricum and Camellia oleifera, and its application. Background Technology

[0002] In recent decades, driven by multiple factors such as climate change, extensive farming practices, and the accelerated adaptive evolution of pathogens, the frequency, severity, and distribution of plant diseases have continued to expand. Global warming, uneven precipitation, and persistent high humidity have reshaped the host-pathogen interaction, both favoring disease outbreaks and weakening the inherent resilience of crops. In the large-scale cultivation of food and medicinal plants, chemical pesticides remain a conventional means of disease control and ensuring stable yields and quality. Conventional fungicides mainly work through systemic absorption, contact, and fumigation. Among these, systemic pesticides can penetrate plant tissues and be transported along the vascular system, exhibiting outstanding efficacy against occult and tissue-colonizing pathogens. Excessive application of these pesticides has led to the accumulation of residues in the edible and medicinal parts of agricultural products, and conventional post-harvest washing is insufficient to effectively remove these compound residues. Therefore, pesticide residue problems not only threaten human health through food and medication but also restrict the standardization, industrialization, and international trade of agricultural products and medicinal herbs. In addition, the long-term overuse of chemical pesticides can disrupt the ecological balance of farmland, accelerate the evolution of pesticide resistance in pathogens, exacerbate the widespread spread of harmful pathogens, and seriously threaten global food security and the stability of agricultural and forestry ecosystems.

[0003] Therefore, current green pest control efforts urgently require the development of novel antibacterial agents that are highly effective, broad-spectrum, stable, environmentally friendly, low-residue, and biosafe. This demand is particularly pressing for high-value horticultural crops and underground rhizomatous economic crops.

[0004] Phytosphingosine, naturally occurring in plants, is a core precursor molecule in plant sphingolipid metabolism, possessing three core functions: structural composition, signal regulation, and immune defense. This substance is not only an important component of the cell membrane but also acts as a second messenger, regulating cell proliferation, differentiation, polar growth, and participating in programmed cell death (PCD). Experiments have shown that phytosphingosine can activate plant defense pathways, induce salicylic acid (SA) and jasmonic acid (JA) signaling, and trigger reactive oxygen species (ROS) bursts. However, its function in controlling plant pathogens and its application in disease management remain unexplored. Summary of the Invention

[0005] This invention aims to provide a broad-spectrum plant-derived fungicide and its application, thereby effectively preventing stem rot and leaf spot caused by Fusarium oxysporum, Fusarium solani, Leucobacterium capitalis, and Botrytis cinerea, significantly reducing the level of pathogen damage, improving the plant's antioxidant and disease resistance, promoting plant growth, and increasing crop yield and quality.

[0006] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution: The application of phytosphingosine in the preparation of a fungicide for controlling plant pathogens, wherein the plant pathogens are selected from at least one of Fusarium oxysporum, Fusarium solani, Leucobacterium capitalis, Staphylococcus aureus, Pseudomonas stolonifera, and Colletotrichum gloeosporioides.

[0007] This invention, through screening different pathogens and conducting experimental verification, demonstrates that phytosphingosine exhibits clear inhibitory activity against a variety of pathogens, indicating that its mechanism of action is broad-spectrum. This overcomes the limitation of some plant-derived active ingredients having a single target, and is of great significance for developing fungicides that simplify application procedures and address complex infections. Furthermore, this invention, by rationally combining phytosphingosine with specific adjuvants (such as organosilicon surfactants), can significantly improve its bioavailability and control efficacy, enabling the achievement of ideal disease control at more efficient concentrations under actual disease pressure. This invention, through the creative selection of phytosphingosine and precise definition of its highly effective pathogen spectrum, ultimately yields a plant-derived fungicide application scheme with broad-spectrum potential, clear efficacy, and the potential for further optimization through formulation technology. Compared to chemical pesticides, plant-derived fungicides based on phytosphingosine directly kill pathogens and activate the plant's own immunity, possessing both direct bactericidal and disease-inducing effects. This is superior to chemical pesticides with a single mode of action. Furthermore, they are easily degradable, leave no residue, and are less likely to induce resistance, which aligns with the development direction of green pesticides.

[0008] Preferably, the fungicide also contains agriculturally acceptable adjuvants.

[0009] Preferably, the additive is an organosilicon surfactant, which includes at least polyether-modified heptamethyltrisiloxane.

[0010] Preferably, the organosilicon surfactant is a trisiloxane-based super-spreading and penetrating agent.

[0011] As a further preferred option, the trisiloxane-based super-spreading and penetrating agent is polyether-modified heptamethyltrisiloxane.

[0012] Preferably, the fungicide includes phytosphingosine, and the concentration of phytosphingosine in the fungicide is 10~1000 μM.

[0013] Preferably, the concentration of phytosphingosine in the fungicide is 50-600 μM.

[0014] Preferably, the fungicide is used to prevent and control plant diseases caused by the plant pathogens.

[0015] Preferably, the plant disease is leaf spot, stem rot, root rot, or anthracnose.

[0016] Preferably, the application is made to injured tissues of plants.

[0017] Preferably, the object of the application includes at least one of Polygonatum sibiricum and Camellia oleifera.

[0018] Preferably, the application is made from the tubers of Polygonatum odoratum or the leaves of Camellia oleifera.

[0019] A broad-spectrum plant-derived fungicide comprising phytosphingosine as the active ingredient as described above, and an agriculturally acceptable carrier, the fungicide being used to control plant pathogens selected from at least one of Fusarium oxysporum, Fusarium solani, Pseudomonas capitalis, Staphylococcus aureus, Pseudomonas stolonifera, and Colletotrichum gloeosporioides.

[0020] A method for controlling plant diseases includes applying an effective amount of phytosphingosine to the plant or the plant's growing environment to control plant pathogens selected from at least one of Fusarium oxysporum, Fusarium solani, Pseudomonas capsulatum, Botrytis cinerea, Pseudomonas stolonifera, and Colletotrichum gloeosporioides.

[0021] Preferably, the plant sphingosine is applied after being compounded with organosilicon adjuvants.

[0022] Therefore, the present invention has the following beneficial effects: (1) This invention has experimentally verified that phytosphingosine has different degrees of inhibitory effect on different plant pathogens, and the inhibition rate increases with the increase of treatment concentration, showing an obvious dose-response relationship. This indicates that its mechanism of action is broad-spectrum and can effectively prevent and control stem rot and leaf spot caused by Fusarium oxysporum, Fusarium solani, Leucobacterium capitalis, and Botrytis cinerea, significantly reducing the level of pathogen damage, improving the antioxidant and disease resistance of plants, promoting plant growth, and improving crop yield and quality. (2) The plant-derived fungicide of the present invention exhibits broad-spectrum antibacterial activity and has a significant inhibitory effect on a variety of agricultural and forestry pathogens such as leaf spot, anthracnose, stem rot, and root rot. It can meet the disease control needs of a variety of economic crops and horticultural plants such as camellia, polygonatum, and tomato. It is especially suitable for the disease control of high-value-added horticultural crops and medicinal plants and has extremely high promotion value and application prospects. (3) Compared with traditional chemical pesticides, phytosphingosine, as a plant-derived agent, has the outstanding characteristics of low residue, easy degradation and environmental friendliness, which is in line with the development direction of green prevention and control in modern agriculture and can be used as an effective alternative to chemical pesticides. Attached Figure Description

[0023] Figure 1 This is a diagram showing the inhibitory effect of phytosphingosine on fungal hyphal growth on PDA medium. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0025] Example 1 The application of phytosphingosine in the preparation of a fungicide for controlling plant pathogens, wherein the plant pathogens are selected from at least one of Fusarium oxysporum, Fusarium solani, Epistylis maxima, Staphylococcus aureus, Epistylis pseudostemum, and Colletotrichum gloeosporioides.

[0026] As one implementation, the fungicide also includes agriculturally acceptable adjuvants, which are organosilicon surfactants, including at least polyether-modified heptamethyltrisiloxane.

[0027] As one implementation method, the organosilicon surfactant is a trisiloxane-based super-spreading and penetrating agent.

[0028] As another implementation method, the trisiloxane-based super-spreading penetrant is polyether-modified heptamethyltrisiloxane.

[0029] As one implementation method, the fungicide includes phytosphingosine, and the concentration of phytosphingosine in the fungicide is 10~1000 μM.

[0030] As another implementation method, the concentration of phytosphingosine in the fungicide is 50~600 μM.

[0031] A broad-spectrum plant-derived fungicide comprising phytosphingosine as the active ingredient as described above, and an agriculturally acceptable carrier, the fungicide being used to control plant pathogens selected from at least one of Fusarium oxysporum, Fusarium solani, Pseudomonas capitalis, Staphylococcus aureus, Pseudomonas stolonifera, and Colletotrichum gloeosporioides.

[0032] The preparation method of the broad-spectrum plant-derived fungicide as described above includes the following steps: S1: Preparation of mother liquor: Accurately weigh the phytosphingosine standard, dissolve it thoroughly in an appropriate amount of dimethyl sulfoxide (DMSO) or ethanol, and bring the volume up to 100 mM or 300 mM with sterile water to make a phytosphingosine stock solution. Store at 4°C in the dark for later use. S2: PDA culture medium preparation: Potato glucose agar (PDA) medium was prepared using conventional methods. 43g of PDA powder (containing agar) was purchased from Hangzhou Microbial Reagent Co., Ltd., and the volume was adjusted to 1 L with distilled water. The medium was then autoclaved at 121℃ for 20 min. S3: Preparation of drug-containing tablets: After the PDA medium has cooled to below 50°C, accurately pipette 100 mM plant sphingosine stock solution into the medium according to the required concentration for the experiment. After shaking well, pour the solution into plates to prepare drug-containing plates with final concentrations of 10, 25, 50, 100, and 200 μM. Use a medium with an equal amount of DMSO added as a blank control. S4: Broad-spectrum plant-derived fungicide: Add 0.05% AgroSpred™ Prime organosilicon adjuvant to 300 mM phytosphingosine stock solution, and dilute with sterile water at ratios of 1:1000 and 1:500 to prepare two concentrations (as treatment solutions): 300 μM (for Fusarium oxysporum) and 600 μM (for Fusarium solani).

[0033] Test strains: *Fusarium oxysporum* and *Fusarium solani* were isolated in July 2023 from diseased *Polygonatum odoratum* plants in a bamboo forest in Qujiang District, Quzhou City, Zhejiang Province. *Phyllosticta capitalensis*, *Botryosphaeria dothidea*, and *Phomopsis sp.* were isolated in July 2022 from leaves of *Camellia oleifera* plants at the Zhejiang Academy of Forestry Sciences. The tested strains are currently preserved at the Institute of Forest Protection, Zhejiang Academy of Forestry Sciences.

[0034] Test plants: Potted rhizomes of Polygonatum odoratum: collected from the experimental planting site of Polygonatum odoratum under forest cover at the Zhejiang Academy of Forestry Sciences. Potted Camellia oleifera seedlings: the experimental population was cultivated in the artificial greenhouse of the Forest Protection Institute of the Zhejiang Academy of Forestry Sciences.

[0035] Test fungicide: To prepare a 100 mM phytosphingosine-dimethyl sulfoxide (DMSO) working solution, a 100 mM phytosphingosine suspension (i.e., phytosphingosine stock solution, prepared as follows: accurately weigh 250 mg of phytosphingosine standard and dissolve it thoroughly in 7.87 mL of dimethyl sulfoxide (DMSO) to obtain a 100 mM phytosphingosine stock solution) was diluted stepwise at volume ratios of 1:10000, 1:4000, 1:2000, 1:1000, and 1:500. The diluted solution was then added to potato dextrose agar (PDA) medium (main components of PDA medium: 10.0 g / L potato extract; 20.0 g / L glucose; 13 g / L agar; 0.1 g / L chloramphenicol) at a temperature below 50℃ to prepare drug-containing plates with final concentrations of 10, 25, 50, 100, and 200 μM.

[0036] Test adjuvant: AgroSpred TM Prime silicone additives, whose main component is polyether-modified heptamethyltrisiloxane, belong to the trisiloxane class of super spreading and penetrating agents.

[0037] Data processing: Experimental data were statistically analyzed using Excel 2019 and SPSS 26 software.

[0038] I. Control effects of phytosphingosine on six pathogenic fungi, including Fusarium oxysporum and Fusarium solani: To clarify the antibacterial activity of phytosphingosine, mycelial growth inhibition experiments were conducted on potato dextrose agar (PDA) medium against various plant pathogens. The inhibitory effects of different concentrations of phytosphingosine on six plant pathogens were determined using the mycelial growth rate method. The inhibitory effects of phytosphingosine on fungal mycelial growth on PDA medium are shown below. Figure 1 As shown.

[0039] Figure 1 The results showed that phytosphingosine had varying degrees of inhibitory effect on all tested pathogens, and the inhibition rate increased with increasing treatment concentration, exhibiting a clear dose-response relationship. At a concentration of 200 μM, phytosphingosine showed the highest inhibition rate against *Botrytis cinerea* (38.94%), followed by *Piper cuspidatum* (42.81%), *Fusarium oxysporum* (27.90%), and *Fusarium solani* (12.36%). The inhibition rates against *Pseudomonas stolonifer* and *Colletotrichum gloeosporioides* were relatively low, at 10.41% and 6.22%, respectively.

[0040] Regression equation, coefficient of determination, and EC50 of phytosphingosine on pathogen growth inhibition 50 The values ​​are shown in Table 1 below.

[0041] Table 1: Capital Leaf Spot Mold y = 0.206x + 10.25 0.968 192 μM Pseudostem mold y = 0.042x + 9.21 0.79 971 μM Fusarium oxysporum y = 0.139x + 13.02 0.982 266 μM Fusarium solani y = 0.046x + 5.81 0.975 961 μM Colloidal anthrax y = 0.018x + 5.62 0.51 2467 μM Staphylococcus aureus y = 0.195x + 10.88 0.989 200 μM

[0042] The regression analysis in Table 1 shows a significant linear correlation between phytosphingosine concentration and antibacterial rate. Specifically, the coefficient of determination (R²⁺) of the regression equations for *Fusarium solani*, *Fusarium oxysporum*, *Leuciscus capitella*, and *Botrytis cinerea* is shown in Table 1. 2 The values ​​of phytosphingosine and phytosphingosine on Fusarium solani were all greater than 0.95, indicating a good fit. Based on the regression equation, the EC50 of phytosphingosine on Fusarium solani was calculated. 50 The value is 961 μM.

[0043] Based on the combined antibacterial effects and regression analysis results, the sensitivity of the six pathogens to phytosphingosine, from highest to lowest, was: *Pseudomonas capsulatum* > *Botrytis cinerea* > *Fusarium oxysporum* > *Fusarium solani* > *Pseudomonas stolonifer* > *Colletotrichum gloeosporioides*.

[0044] II. Pesticide adjuvants significantly improve the inhibition efficiency of pathogens: The test adjuvant was added at a ratio of 0.05% (v / v) and thoroughly mixed with a 200 μM phytosphingosine solution (i.e., a 100 mM phytosphingosine-DMSO stock solution diluted 1:500) to prepare the phytosphingosine agent. The regression equation, coefficient of determination, and EC50 of the mixed solution on the inhibition of pathogen growth were determined. 50 The values ​​are shown in Table 2 below.

[0045] Table 2: Capital Leaf Spot Mold y = 0.378x + 12.35 0.989 99.6 μM Pseudostem mold y = 0.169x + 17.22 0.962 193.9 μM Fusarium oxysporum y = 0.324x + 23.55 0.992 81.6 μM Fusarium solani y = 0.171x + 13.22 0.985 215.1 μM Colloidal anthrax y = 0.144x + 14.33 0.978 247.7 μM Staphylococcus aureus y = 0.341x + 11.55 0.995 112.7 μM

[0046] Analysis of Table 2 shows that the addition of the tested adjuvants significantly improved the fungicidal effect of the plant-derived agents, and the inhibition rate increased significantly with increasing concentration. The sensitivity, from highest to lowest, was: *Fusarium oxysporum* > *Pseudomonas capsulatum* > *Botrytis cinerea* > *Pseudomonas stolonifer* > *Fusarium solani* > *Colletotrichum gloeosporioides*. Regression analysis showed a significant linear correlation between concentration and inhibition rate, R0. 2 All values ​​> 0.96, indicating good fit. *Fusarium oxysporum* was the most sensitive, with EC50 values ​​> 0.96. 50 The concentration was only 81.6 μM, indicating that the compound agent has the potential to effectively inhibit Fusarium pathogens.

[0047] The fungicide formulation of this invention exhibits broad-spectrum antibacterial activity, showing significant inhibitory effects against various agricultural and forestry pathogens, including leaf spot, anthracnose, stem rot, and root rot. It is suitable for disease control needs in various economic crops and horticultural plants such as camellia oleifera, polygonatum, and tomato. Compared to traditional chemical pesticides, phytosphingosine, as a plant-derived agent, has the outstanding characteristics of low residue, easy degradation, and environmental friendliness, aligning with the development direction of green pest control in modern agriculture and serving as an effective alternative to chemical pesticides. In the future, it can be applied in various scenarios such as protected cultivation, field planting, and understory economic crop cultivation through foliar spraying, root application, etc., and is particularly suitable for disease control of high-value-added horticultural crops and medicinal plants, possessing extremely high promotional value and application prospects.

[0048] III. Control effects of phytosphingosine on two pathogenic fungi of Polygonatum rhizome inoculation with wounds: Experimental Design: The tested plant material was the tubers of potted *Polygonatum cyrtonema* seedlings, which were surface-sterilized before use. The tested pathogens included *Fusarium oxysporum* and *Fusarium solani*. The concentration of the spore suspensions (prepared as follows: activated pathogen strains were inoculated onto PDA plates, incubated at 25°C for 7 days, spores were washed off with sterile water, mycelia were removed by filtration through four layers of gauze, spores were counted using a hemocytometer, and the spore concentration was adjusted) was 1×10⁻⁶. 6 CFU / mL. The test adjuvant was AgroSpred. TM Prime organosilicon adjuvant, added at a concentration of 0.05%. The test reagent was phytosphingosine emulsion (prepared as follows: phytosphingosine standard was dissolved in ethanol, 0.05% AgroSpred™ Prime organosilicon adjuvant was added, and the volume was adjusted to 300 mM phytosphingosine stock solution with sterile water). It was diluted at ratios of 1:1000 and 1:500 to prepare two concentrations: 300 μM (for *Fusarium oxysporum*) and 600 μM (for *Fusarium solani*) (as treatment solutions). The experiment used a wound inoculation method. After artificially creating tiny wounds on the surface of *Polygonatum sibiricum* tubers, 20 μL of spore suspension was added to each tuber, along with 20 μL of either the treatment solution or the control solution, and the mixture was kept moist for 48 h. Each treatment had 30 plants, replicated three times, with 10 plants per replicate. The disease incidence was assessed 30 days after inoculation. Disease was defined as the appearance of typical browning, rotting, or visible mycelial coverage on the tuber. In the Fusarium oxysporum test, the treatment group used 300 μM phytosphingosine emulsion, while the control group used an equal volume of sterile water (both containing 0.05% AgroSpred). TMPrime); In the Fusarium rot test, the treatment group used 600 μM phytosphingosine emulsion, while the control group used an equal volume of sterile water (containing 0.05% AgroSpred). TM The comparison of the incidence rates of two pathogens after inoculation of Polygonatum rhizome with phytosphingosine emulsion is shown in Table 3 below.

[0049] Table 3:

[0050] Note: Incidence rate = number of infected plants / total number of plants; Average incidence rate = (total number of infected plants / total number of plants) × 100%.

[0051] The relative protective efficacy is calculated using the following formula: Relative efficacy = (control incidence rate - treatment incidence rate) / control incidence rate × 100%.

[0052] Based on the data in Table 3, calculate the relative control efficacy of phytosphingosine emulsion against Fusarium oxysporum and Fusarium solani. The relative efficacy against Fusarium oxysporum = (incidence rate in the control group - incidence rate in the treatment group) / incidence rate in the control group × 100% = (83.3% - 26.7%) / 83.3% × 100% = 67.9%; The relative control efficacy against Fusarium solani = (incidence rate of control group - incidence rate of treatment group) / incidence rate of control group × 100% = (83.3% - 46.7%) / 83.3% × 100% = 43.9%.

[0053] Based on the data in Table 3, 30 days after inoculation with Fusarium oxysporum, the average disease incidence rate of Polygonatum rhizomes in the control group was 83.3%, while the average disease incidence rate in the Polygonatum rhizomes treated with phytosphingosine emulsion (300 μM) was 26.7%, with a relative control efficacy of 67.9%. Independent samples t-tests performed using SPSS 26 software showed a highly significant difference between the two groups (t=12.02, df=4, p<0.01).

[0054] Thirty days after inoculation with Fusarium solani, the average disease incidence rate of Polygonatum rhizome in the control group was 83.3%, while that in the group treated with phytosphingosine emulsion (600 μM) was 46.7%, with a relative control efficacy of 43.9%. The t-test results showed that the difference between the two groups was also highly significant (t=7.78, df=4, p<0.01).

[0055] Under the conditions of this experiment, phytosphingosine emulsion showed significant control effects against both Fusarium oxysporum and Fusarium solani fungi on Polygonatum tubers after wound inoculation, but the control efficacy differed significantly: the relative control efficacy of phytosphingosine emulsion against Fusarium oxysporum was 67.9%, while that against Fusarium solani was 43.9%. The incidence rate in the control groups remained stable at 83.3% in both experiments, indicating that the wound inoculation model was stable and reliable. In conclusion, phytosphingosine emulsion can effectively inhibit the infection of Polygonatum tubers by Fusarium oxysporum and Fusarium solani fungi, especially showing excellent protection against rot caused by Fusarium oxysporum, and has the potential to be developed into a green control agent for Fusarium solani diseases in Polygonatum.

[0056] IV. The control effect of phytosphingosine on four pathogens of tea leaves after inoculation with wounds: Experimental Design: Using detached leaves of Camellia oleifera as material, after surface sterilization, uniform punctures (5 puncture points per leaf) were made on the upper surface of the leaves using a sterile needle. Spore suspensions of four pathogens (Phomacapituliformis, Phopsis sp., Colletotrichum gloeosporioides, and Botryosphaeria dothidea) were prepared separately (the preparation method is as follows: the tested pathogen strains were inoculated into PDA medium and cultured at 25℃ for 7-10 days; the spores were washed with sterile 0.05% Tween-80 aqueous solution; and mycelial fragments were removed by filtration through four layers of sterile gauze to prepare the spore suspension). The concentration was adjusted to 1×10⁻⁶ using a hemocytometer. 6 CFU / mL, refrigerated at 4℃ for later use. The treatment group used phytosphingosine emulsion (300 μM, supplemented with 0.05% AgroSpred). TM Prime was used as a spreading agent (i.e., an adjuvant) as the treatment solution, while the control group used an equal volume of sterile water (containing the same concentration of AgroSpred). TM Prime was used as a control solution. After each leaf was punctured, 20 μL of spore suspension was added, along with 20 μL of either the treatment solution or the control solution, and the mixture was kept moist for 48 h. Each group had 30 leaves per pathogen, with three replicates (10 leaves per replicate). Leaf disease incidence was assessed 14 days after inoculation (the appearance of typical lesions or tissue necrosis was considered diseased). The comparison of disease incidence rates after inoculation of four pathogens onto *Tea oleifera* leaves treated with phytosphingosine emulsion (300 μM) is shown in Table 4 below.

[0057] Table 4:

[0058] Note: Incidence rate = number of infected plants / total number of plants; Average incidence rate = (total number of infected plants / total number of plants) × 100%.

[0059] The relative protective efficacy is calculated using the following formula: Relative efficacy = (control incidence rate - treatment incidence rate) / control incidence rate × 100%.

[0060] Analysis of the data in Table 4 shows that at a concentration of 300 μM, phytosphingosine emulsion has a significant control effect on all four pathogens of Camellia oleifera, but the differences in control efficacy are similar to those observed in vitro EC. 50 The trends were consistent: the highest control efficacy (84.7%) was observed against the most sensitive *Pseudomonas capsulatum*, followed by *Botrytis cinerea* (72.0%), and the control efficacy against the less sensitive *Pseudomonas stolonifer* and *Colletotrichum gloeosporioides* was 52.2% and 43.9%, respectively. These results indicate that phytosphingosine can effectively reduce the risk of disease after inoculation with wounded *Camellia oleifera* leaves, and its in vivo protective effect is positively correlated with its in vitro antibacterial activity.

[0061] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. The application of phytosphingosine in the preparation of fungicides for controlling plant pathogens, characterized in that, The plant pathogens are selected from at least one of Fusarium oxysporum, Fusarium solani, Epistylis maxima, Staphylococcus aureus, Epistylis pseudostemia, and Colletotrichum gloeosporioides.

2. The application according to claim 1, characterized in that, The fungicide also contains agriculturally acceptable adjuvants.

3. The application according to claim 2, characterized in that, The additive is an organosilicon surfactant, which includes at least polyether-modified heptamethyltrisiloxane.

4. The application according to claim 1 or 2, characterized in that, The fungicide includes phytosphingosine, and the concentration of phytosphingosine in the fungicide is 10~1000 μM.

5. The application according to claim 4, characterized in that, The concentration of phytosphingosine in the fungicide is 50-600 μM.

6. The application according to claim 1 or 2, characterized in that, The fungicide is used to prevent and control plant diseases caused by the plant pathogens.

7. The application according to claim 6, characterized in that, The plant diseases mentioned are leaf spot, stem rot, root rot, or anthracnose.

8. The application according to claim 1, characterized in that, The objects to be applied include at least one of Polygonatum sibiricum and Camellia oleifera.

9. The application according to claim 8, characterized in that, The application targets are the tubers of Polygonatum odoratum or the leaves of Camellia oleifera.

10. A broad-spectrum plant-derived fungicide, characterized in that, The fungicide comprises phytosphingosine as an active ingredient in any one of claims 1 to 9, and an agriculturally acceptable carrier, for controlling plant pathogens selected from at least one of Fusarium oxysporum, Fusarium solani, Pseudomonas capitalis, Staphylococcus aureus, Pseudomonas stolonifera, and Colletotrichum gloeosporioides.

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