Method for improving clubroot resistance of cruciferous plants

Abstract

The invention provides a method for improving clubroot resistance of cruciferous plants. It is found for the first time that probenazole treatment can improve the resistance of Chinese cabbages to clubroot and inhibit the vitality of plasmodiophora brassicae spores. The morbidity and the disease index of the Chinese cabbage clubroot can be reduced through pretreatment with probenazole of different concentrations and different dosage forms, the disease development is delayed, and adverse effects on the growth of Chinese cabbages cannot be caused. The probenazole suspending agent and the nanocapsule suspending agent prepared by the invention have outstanding prevention and control effects on clubroot of cruciferous plants.

Description

Technical Field

[0001] This invention belongs to the field of plant disease control, and specifically relates to a method for improving the resistance of cruciferous plants to clubroot disease. Background Technology

[0002] Clubroot disease is caused by the fungus *Cladosporium brassicum* (Bacterium tumefaciens). Plasmodiophora brassicae Clubroot (Brassica napus) is one of the most destructive soil-borne diseases affecting cruciferous crops, causing significant losses to global agricultural production. Currently, more than 60 countries worldwide are affected, and it has occurred in more than 20 provinces (autonomous regions and municipalities) in East my country, North China, Central China, and Southwest China. Clubroot, belonging to the class Plasmomycetes of the phylum Uropoda in the kingdom Protozoa, is an obligate parasitic, biotrophic pathogen. Its dormant spores are highly resistant and can survive in the soil for more than ten years. In recent years, with the expansion of cruciferous crop planting areas, the increase in continuous cropping years, the intermodal transport of vegetables between the north and south, and changes in the soil environment, clubroot has spread rapidly and worsened year by year in my country, posing a challenge to its control.

[0003] Allylbenzylthiazide (PBZ, CAS No. 27605-76-1) is an immune-inducing fungicide developed by Meiji Seika Co., Ltd. of Japan. It was first used in Japan in 1975 to control rice blast. Currently, PBZ is only registered for use on rice for the control of rice blast. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the resistance of cruciferous plants to clubroot disease.

[0005] In order to achieve the purpose of this invention, in a first aspect, this invention provides the application of allylbenzylthiazide in the prevention and control of clubroot disease in cruciferous plants (such as Chinese cabbage).

[0006] In this invention, the clubroot disease is caused by *Cladosporium brassicum* (a fungus that causes clubroot infection). Plasmodiophora brassicae Woron. is caused by the infection of plants.

[0007] Secondly, the present invention provides a method for improving the resistance of cruciferous plants (such as Chinese cabbage) to clubroot disease, the method comprising: applying a salicylic acid signaling pathway activator to the cruciferous plants.

[0008] The salicylic acid signaling pathway activator includes allylbenzylthiazol.

[0009] Furthermore, an allylbenzylthiazide solution was applied to the roots of cruciferous plants.

[0010] The application concentration of the allylphenthiazole solution is 100-400 mg / L (preferably 250 mg / L). The allylphenthiazole solution comprises an aqueous solution of allylphenthiazole with a 0.5% acetone content, as well as the allylphenthiazole suspension and allylphenthiazole nanoformulation (allylphenthiazole nanocapsule suspension) prepared according to this invention.

[0011] Furthermore, the clubroot resistance includes delaying the occurrence of clubroot in cruciferous plants and / or alleviating clubroot symptoms.

[0012] Thirdly, the present invention provides a medicament for preventing clubroot disease in cruciferous plants, the medicament comprising allylbenzylthiazide, optionally including excipients.

[0013] Further, the agent is a 1-40% allylphenthiazole suspension or a 1-2% allylphenthiazole nanocapsule suspension. The excipients used to prepare the suspension include any one or more of wetting agents, thickeners, antifreeze agents, preservatives, defoamers, and dispersants.

[0014] By employing the above technical solution, the present invention has at least the following advantages and beneficial effects: This invention provides a method for improving the resistance of cruciferous plants to clubroot disease. This is the first report of the use of allylphenthiazole, an activator of the salicylic acid signaling pathway, in the control of clubroot disease in cruciferous plants. The efficacy of allylphenthiazole in controlling clubroot disease in Chinese cabbage was verified by applying different concentrations to the roots of clubroot-susceptible Chinese cabbage; the effects of different concentrations of allylphenthiazole on the growth of Chinese cabbage were also investigated. Experimental results showed that root irrigation with a 250 mg / L allylphenthiazole solution significantly reduced the incidence and disease index of clubroot disease and had a killing effect on clubroot spores. Furthermore, both allylphenthiazole suspension and nanocapsule suspension treatments showed good control effects against clubroot disease in cruciferous plants; in particular, the nanocapsule suspension significantly improved the resistance of cruciferous plants to clubroot disease. This invention provides a new strategy for the control of clubroot disease in cruciferous plants. Attached Figure Description

[0015] Figure 1 This invention illustrates the effect of different concentrations of PBZ on the plant height and crown width of Chinese cabbage in a preferred embodiment. A represents the plant height of Chinese cabbage; B represents the crown width of Chinese cabbage.

[0016] Figure 2 The effects of different concentrations of PBZ on the stem diameter, leaf length, and leaf width of Chinese cabbage are shown in the preferred embodiment of the present invention. A represents the stem diameter of Chinese cabbage; B represents the leaf length of Chinese cabbage; and C represents the leaf width of Chinese cabbage.

[0017] Figure 3 This invention illustrates the effect of different concentrations of PBZ treatment on the fresh weight of the above-ground parts and root length of Chinese cabbage in a preferred embodiment. A represents the fresh weight of the above-ground parts; B represents the root length.

[0018] Figure 4 This invention illustrates the effects of different concentrations of PBZ treatment on electrolyte leakage and chlorophyll content in Chinese cabbage leaves in a preferred embodiment. A represents the electrolyte leakage rate; B represents the chlorophyll content.

[0019] Figure 5 This invention illustrates the occurrence of clubroot disease in Chinese cabbage after treatment with different concentrations of PBZ in a preferred embodiment. A represents the disease phenotype of the Chinese cabbage roots 30 days after inoculation with clubroot fungus; B represents the percentage of disease severity grades in different PBZ treatment groups 30 days after inoculation with clubroot fungus; C represents the incidence rate of disease in different PBZ treatment groups 30 days after inoculation with clubroot fungus; and D represents the disease index of different PBZ treatment groups 30 days after inoculation with clubroot fungus.

[0020] Figure 6 This is a preferred embodiment of the invention showing the viability of *Plasmodiophora* spores after PBZ treatment. A shows trypan blue staining of *Plasmodiophora* spores in the control group; B shows trypan blue staining of *Plasmodiophora* spores in the PBZ group; C shows the survival rate statistics of spores in the two treatment groups. Obvious blue deposition inside the spores indicates that the spores have lost their viability.

[0021] Figure 5 and Figure 6 In the text, * indicates P <0.05, ** indicates P <0.01. Detailed Implementation

[0022] This invention provides a novel method for controlling clubroot disease in cruciferous vegetables. During previous research on the interaction mechanism between clubroot pathogens and Chinese cabbage, the inventors discovered that the salicylic acid pathway is activated and plays a positive role in the resistance of Chinese cabbage to clubroot pathogens. It is hypothesized that exogenous application of salicylic acid pathway activators can enhance the resistance of cruciferous vegetables to clubroot disease. Therefore, the following research was conducted, proposing a new technical means for the control of clubroot disease in cruciferous plants such as Chinese cabbage.

[0023] The present invention adopts the following technical solution: This invention provides a method for preventing clubroot disease in cruciferous plants, comprising the method and steps of applying a salicylic acid signaling pathway activator to the roots of the cruciferous plants.

[0024] The salicylic acid signaling pathway activator mentioned above includes allylbenzylthiazol.

[0025] Furthermore, the application concentration of the allylphenthiazide is 100-400 mg / L (preferably 250 mg / L).

[0026] The cruciferous plants mentioned include Chinese cabbage.

[0027] This invention also provides the application of allylbenzylthiazol in improving plant resistance to clubroot disease.

[0028] Furthermore, the clubroot resistance includes delaying the onset of clubroot and / or alleviating clubroot symptoms.

[0029] The present invention also provides a medicament for preventing clubroot disease in cruciferous plants, the medicament comprising allylbenzylthiazide.

[0030] Furthermore, the pharmaceutical preparation also contains excipients.

[0031] Furthermore, the excipients include any one or more of wetting agents, thickeners, antifreeze agents, preservatives, defoamers, and dispersants.

[0032] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0033] The allylphenthiazole solutions applied in the following examples include an allylphenthiazole aqueous solution with an acetone content of 0.5%, as well as the allylphenthiazole suspension and allylphenthiazole nanocapsule suspension prepared in this invention.

[0034] Example 1: Effect of allylphenthiazide on the growth of Chinese cabbage

[0035] 1. Germination

[0036] The Chinese cabbage used in the experiment was a clubroot-susceptible variety (Zhongbai 76), purchased from China Vegetable Seed Industry Technology (Beijing) Co., Ltd. Plump Chinese cabbage seeds were selected, disinfected with 75% ethanol for 5 minutes, and then rinsed 3-5 times with sterile water. Two layers of filter paper were placed in a petri dish, with a small amount of sterile water added to keep the filter paper moist. The disinfected seeds were then evenly placed on the filter paper, and covered with another layer of moistened filter paper. Germination was carried out at 25℃ in the dark for three days.

[0037] 2. Sowing

[0038] Sow the uniformly sized seedlings after germination in 5 cm square flowerpots using a general-purpose seedling substrate. Water every three days.

[0039] 3. Administration of allylphenthiazide

[0040] When Chinese cabbage reaches the two-leaf-one-heart stage, roots are treated with 100 mg / L and 250 mg / L allylbenzylthiazide solutions, 2 mL per plant, for a total of three treatments, with an interval of three days. The control is treated with a 0.5% acetone aqueous solution.

[0041] 4. Measurement of physiological indicators

[0042] To further evaluate the safety of allylbenzylthiazide application on Chinese cabbage, a cruciferous vegetable, plant height, crown width, stem diameter, leaf length, and leaf width were measured after 10, 20, 25, and 30 days of root drenching with different concentrations of allylbenzylthiazide aqueous solution. On day 15, chlorophyll content and electrolyte leakage were measured.

[0043] (1) Determination of chlorophyll content

[0044] Fifteen days after treatment with allylbenzylthiazide, 0.1 g of leaf samples were ground with liquid nitrogen, and then extracted with an extraction buffer (acetone:ethanol:water = 4.5:4.5:1, volume ratio) by vortexing for 1 min. The mixture was then centrifuged at 6000 rpm for 5 min, and the supernatant was retained. Using the extract as a blank control, the absorbance of the supernatant at 645 nm and 663 nm was measured using a UV spectrophotometer. The total chlorophyll content was calculated.

[0045] Total chlorophyll content (mg / g FW) = (20.29A) 645 +8.05A 663 )×V / (W×1000)

[0046] (2) Determination of electrolyte leakage in leaves

[0047] To investigate whether high concentrations of allylphenthiazole affected the cell membranes of Chinese cabbage leaves, the electrolyte leakage rate of the leaves was measured after 15 days of allylphenthiazole treatment. Approximately 0.1 g of intact leaves were soaked in water at room temperature for 2 hours, and the conductivity (C1) was measured. The solution was then boiled in a boiling water bath for 20 minutes, cooled, and the conductivity was measured again (C2). Electrolyte leakage rate in leaves (%) = C1 / C2 × 100%

[0048] 5. Experimental Results

[0049] The physiological indicators of Chinese cabbage were investigated after treatment with allylphenthiazide for different durations. The results showed that treatments with 100 mg / L and 250 mg / L of allylphenthiazide did not affect the plant height or crown width of Chinese cabbage. Figure 1 ), stem thickness, leaf length and leaf width ( Figure 2 This had an impact. After 15 days of allylbenzylthiazide treatment, there was no significant difference in electrolyte leakage in Chinese cabbage leaves compared to the control group, but the total chlorophyll content increased slightly. Figure 3 After 30 days of treatment, the fresh weight of the above-ground parts of the Chinese cabbage in the treatment group was not different from that in the control group, but the root length increased slightly. Figure 4 ).

[0050] Example 2: Control effect of allylbenzylthiazide on clubroot disease in Chinese cabbage

[0051] 1. Germination

[0052] After disinfecting the Chinese cabbage (Zhongbai 76) with 95% ethanol, it was cultured in the dark in sterilized moist filter paper to promote germination.

[0053] 2. Sowing

[0054] Select uniformly sprouted cabbage seedlings and sow them in 5 cm square flowerpots. Use a general-purpose seedling substrate and water every three days. Cultivate in a plant light incubator with 16 hours of light and 8 hours of darkness at a temperature of 22ºC-25ºC.

[0055] 3. Administration of allylphenthiazide

[0056] When Chinese cabbage reaches the two-leaf-one-heart stage, roots are treated with 100 mg / L and 250 mg / L allylbenzylthiazide solutions, 2 mL per plant, for a total of three treatments, with an interval of three days. The control is treated with a 0.5% acetone aqueous solution.

[0057] 4. Inoculation with clubroot pathogen

[0058] The clubroot tissue was collected from Xia Dabai Village, Songhua Township, Panlong District, Kunming City, Yunnan Province, and stored at -20℃. After being removed from the storage, the clubroots were incubated for three days in a constant temperature incubator at 26-28℃, protected from light. The mixture was then homogenized using a high-speed blender, a small amount of sterile water was added, and the mixture was filtered through eight layers of gauze. The residue was discarded, and the spores were counted using a hemocytometer. The concentration of the spore suspension was adjusted to 10. 7 Prepare spores / mL for use. Five days after application of the agent, inoculate the roots with the prepared spore suspension, using 2 mL of bacterial suspension per cabbage plant. The control treatment is treated with 2 mL of sterile water.

[0059] 5. Disease investigation

[0060] Disease resistance was assessed 30 days after inoculation, and was graded into four levels: Level 0, no symptoms, i.e., resistant and immune; Level 1, small nodules on fibrous roots, no visible nodules on the taproot and hypocotyl; Level 2, taproot slightly swollen, fibrous roots with large or small nodules; Level 3, hypocotyl and taproot significantly swollen, fibrous root nodules prominent, plant growth affected; Level 4, large root swellings on the hypocotyl, roots completely destroyed, plant withered. The disease level of each plant was recorded, and the disease index and incidence rate were calculated.

[0061] Incidence rate (%) = Number of infected plants / Total number of plants × 100%

[0062] Disease index = [Σ(Number of diseased plants at each level × Disease level value) / (Total number of plants surveyed × Highest level value)] × 100

[0063] 6. Experimental Results

[0064] Different concentrations of allylphenthiazide were used to drench the roots of infected Chinese cabbage. Five days after treatment, the cabbage was inoculated with clubroot pathogens, and the incidence of clubroot disease was investigated. The results showed that allylphenthiazide treatment enhanced the resistance of Chinese cabbage to clubroot disease. Drenching with 250 mg / L allylphenthiazide significantly reduced the incidence and disease index of clubroot disease, and the clubroot phenotype in Chinese cabbage was significantly weakened. Figure 5 ).

[0065] Example 3: Effect of allylphenthiazide on the spore viability of *Plasmodiophora*

[0066] 1. Preparation of root exudates

[0067] Line a petri dish with three layers of sterilized filter paper. Disinfect Chinese cabbage seeds with 75% alcohol for 8–10 minutes, rinse 6–7 times with sterile water, and place 50 seeds per dish in the petri dish to germinate. After germination, transfer to MS medium for culture. Once the seeds have developed two true leaves (approximately one week), collect the culture medium and filter it through a 0.22 μm bacterial filter to obtain the root exudate solution. Store this solution at 4°C for later use.

[0068] 2. Preparation and purification of *Plasmodiophora* spores

[0069] Tissue samples of clubroot diseased Chinese cabbage were collected from a severely diseased field in Xia Dabai Village, Songhua Township, Kunming City, Yunnan Province (25° N, 102° E). ​​The dominant physiological race 11 was identified as the clubroot pathogen. (Yuan Jiasheng, He Saiya, Zhang Jinhao, Qiu Yue, Wang Bowen, Meng Han, Wei Lanfang, Ji Guanghai. Identification of Pseudomonas brassicae JP2 and its control effect on clubroot disease of Chinese cabbage [J / OL]. Acta Phytopathologica Sinica). Take clubroot diseased tissue from Chinese cabbage, wash it, and incubate it in a constant temperature incubator at 26-28℃ for 3 days in the dark. After it rots, add water and blend it into a homogenate using a high-speed blender. Filter the homogenate through 8 layers of gauze, discard the residue, and transfer the filtrate into 50 mL sterile centrifuge tubes, 25-30 mL per tube. Centrifuge at 500 rpm for 10 min, discard the precipitate, and transfer the supernatant to a new 50 mL centrifuge tube. Centrifuge the transferred supernatant at 5000 rpm for 15 min, discard the supernatant, and resuspend the precipitate thoroughly in distilled water. Repeat this step 2-3 times. Discard the supernatant, resuspend the precipitate thoroughly in 50% (w / v) sucrose solution, centrifuge at 5000 rpm for 15 min, transfer the supernatant to a new 50 mL centrifuge tube, add an equal or greater volume of sterile water to the supernatant, mix thoroughly, and centrifuge at 5000 rpm for 15 min. Repeat this operation 5 times to wash away the sucrose; discard the supernatant, suspend the spores in root exudate, and adjust the spore concentration of the suspension to 10 using a hemocytometer. 7 per mL.

[0070] 3. Detection of Plasmodium spore viability

[0071] Mix the prepared allylbenzylthiazide reagent with the spore suspension to achieve a reagent concentration of 250 mg / L, and incubate at 25ºC in the dark for 3 days. Add 0.4% trypan blue solution to the cultured spore suspension at a 1:1 ratio, mix well, and incubate at room temperature for 5-10 min. Observe the staining of the spores under a microscope and record the number of dead and live spores. Spore survival rate (%) = (Number of live spores / Total number of spores investigated) × 100%.

[0072] 4. Experimental Results

[0073] Incubation of a suspension of *Plasmodiophora* spores with 250 mg / L allylphenthiazide and subsequent trypan blue staining revealed a significant decrease in spore viability after allylphenthiazide treatment, indicating that allylphenthiazide has a toxic effect on *Plasmodiophora* spores. Figure 6 ).

[0074] Example 4: Comparison of the control effects of allylbenzylthiazide and benzothiadiazole on clubroot disease in Chinese cabbage

[0075] Benzothiadiazole (BTH) is a synthetic functional analogue of salicylic acid that can induce durable disease resistance in various plants (Zhang Yue, Yang Dongyan, Zhang Nailou, Qi Xin, Hao Zesheng, Chen Lei, Fan Zhijin. Research progress on plant disease resistance activators [J]. China Science Foundation, 2020, 34 (04): 519-528). Following the treatment and inoculation methods in Example 2, Chinese cabbage was treated with root irrigation using 50 mg / L BTH solution and 250 mg / L allylbenzylthiazide solution, respectively. Disease development was investigated 20 and 30 days after inoculation. The results showed that on day 20 after inoculation, the disease incidence in the allylbenzylthiazide treatment group was significantly lower than that in the BTH and CK groups. On day 30 after inoculation, most Chinese cabbage in different treatment groups showed disease symptoms. Comparatively, the allylbenzylthiazide treatment group had the lowest disease index, followed by the BTH treatment group, while the CK group had the most severe disease (Table 1). The results showed that both BTH and allylphenthiazide could enhance the resistance of Chinese cabbage to clubroot and delay the development of the disease; compared with BTH treatment, allylphenthiazide treatment was more effective in inducing resistance in Chinese cabbage.

[0076] Table 1. Disease progression of clubroot disease in Chinese cabbage after treatment with PBZ and benzothiadiazole (BTH)

[0077] Example 5 Preparation of allylbenzylthiazol suspension

[0078] The formulation of allylbenzylthiazide suspension concentrate is as follows (mass percentage): Allylphenthiazide 1~40%

[0079] Atlox 4913 dispersant 3%

[0080] Atlox 4894 2% wetting and dispersing agent

[0081] Thickener xanthan gum 0.05%

[0082] Antifreeze ethylene glycol 5%

[0083] Preservative Benzisothiazolin-3-one 0.1%

[0084] Defoamer SAG1572 0.1%

[0085] Replenish water to 100%.

[0086] Weigh the materials according to the above proportions. After weighing, use high-speed shearing to mix the materials evenly. Wet grind for 2-3 hours and discharge the material to obtain allylbenzylthiazol suspension.

[0087] Example 6 Preparation of allylbenzylthiazol nanocapsule suspension

[0088] The formulation of 1-2% allylbenzylthiazol nanocapsule suspension is as follows (mass percentage): Allylphenidazole 1-2%

[0089] Solvent: 10% cyclohexanone

[0090] Solvent S-150 1%

[0091] Emulsifier Agricultural Emulsion 601# 5%

[0092] 4% MDI trimer in wall materials

[0093] Dibutyltin dilaurate 0.02%

[0094] Dispersant WG4 2%

[0095] Thickener xanthan gum 0.1%

[0096] Antifreeze ethylene glycol 5%

[0097] Defoamer SAG1572 0.1%

[0098] Replenish deionized water to 100%.

[0099] 1-2 g of allylphenthiazole was mixed with 10 g of cyclohexanone and 1 g of S-150, and stirred until the drug was dissolved. Then, 4 g of MDI trimer (Wanhua), 5 g of agricultural emulsion 601#, and 0.02 g of dibutyltin dilaurate were added and stirred until homogeneous to prepare the oil phase. 2 g of dispersant WG4 (Jieshi Chemical (Shanghai) Co., Ltd.) was dissolved in deionized water and stirred until dissolved to prepare the aqueous phase. The oil phase was poured into the aqueous phase at a shear rate of 20,000 rpm and sheared for 3 min to obtain an emulsion. The emulsion was heated to 55°C with stirring at 300 rpm and kept at that temperature for 2 h. After heating was stopped and the mixture was cooled to room temperature, the remaining components, including thickener, antifreeze, preservative, and defoamer, were added in proportion and stirred until homogeneous to obtain a 1% allylphenthiazole nanocapsule suspension.

[0100] Example 7: Control efficacy of two allylbenzylthiazol suspensions against clubroot disease in Chinese cabbage.

[0101] 1. Preparation of the medicine

[0102] Dilute 30% allylphenthiazole suspension 1200 times with water and stir thoroughly to achieve a final concentration of 250 mg / L for the active ingredient. Dilute 2% allylphenthiazole nanocapsule suspension 80 times with water and stir thoroughly to achieve a final concentration of 250 mg / L for the active ingredient.

[0103] 2. Inoculation and disease investigation of *Plasmodiophora stylosa*

[0104] Following the method described in Example 2, Chinese cabbage was planted, and clubroot spores were isolated and collected. At the two-leaf-one-heart stage of the Chinese cabbage, roots were drenched with 2 mL of 250 mg / L allylphenthiazole microcapsule suspension, 250 mg / L allylphenthiazole microcapsule suspension, and a water control, respectively, for a total of three treatments, with an interval of three days. Five days after treatment, clubroot was inoculated, and disease control was assessed at 30 and 50 days.

[0105] Prevention and control efficacy (%) = (Control group disease index - Treatment group disease index) / Control group disease index × 100%

[0106] Table 2 shows that, 30 days after inoculation, the control efficacy of allylbenzylthiazole suspension against clubroot disease in Chinese cabbage was 51.78%; however, after 50 days, the control efficacy decreased to 39.61%. The control efficacy of allylbenzylthiazole nanocapsule suspension against clubroot disease in Chinese cabbage was 62.33% after 30 days and 50.39% after 50 days. Compared to allylbenzylthiazole suspension, the nanocapsule suspension showed better control efficacy against clubroot disease.

[0107] Table 2. Control effects of PBZ suspension (SC) and nanocapsule suspension (NCS) on clubroot disease in Chinese cabbage.

[0108] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. Application of allylbenzylthiazide in the control of clubroot disease in cruciferous plants.

2. A method for improving the resistance of cruciferous plants to clubroot disease, characterized in that, The method includes: applying a salicylic acid signaling pathway activator to cruciferous plants; The salicylic acid signaling pathway activator includes allylphenthiazole.

3. The method according to claim 2, characterized in that, Apply allylbenzylthiazide solution to the roots of cruciferous plants.

4. The method according to claim 3, characterized in that, The application concentration of allylbenzylthiazide solution is 100-400 mg / L; The allylbenzylthiazole solution includes an allylbenzylthiazole aqueous solution with an acetone content of 0.5%, an allylbenzylthiazole suspension, and an allylbenzylthiazole nanoformulation.

5. The method according to claim 2, characterized in that, The cruciferous plants mentioned include Chinese cabbage.

6. The method according to claim 2, characterized in that, The clubroot resistance includes delaying the onset of clubroot and / or alleviating clubroot symptoms.

7. The method according to any one of claims 2-6, characterized in that, The clubroot disease is caused by the fungus *Cladophora brassicae* (…). Plasmodiophora brassicae Woron. is caused by the infection of plants.

8. A fungicide for controlling clubroot disease in cruciferous plants, characterized in that, The pharmaceutical preparation contains allylphenthiazide, with optional excipients.

9. The pharmaceutical preparation according to claim 8, characterized in that, The agent is 1-40% allylbenzylthiazide suspension or 1-2% allylbenzylthiazide nanocapsule suspension; The excipients used to prepare the suspension include any one or more of wetting agents, thickeners, preservatives, defoamers, antifreeze agents, and dispersants.

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