A method for controlling Canadian goldenrod using AVG in synergy with SD1 bacteria

Abstract

This invention discloses a method for controlling Canadian goldenrod using AVG in synergy with SD1 bacteria, belonging to the field of biological control technology. This invention utilizes the pathogenic bacterium SD1 combined with 500 μmol / L AVG, opening up a new control pathway for invasive weeds such as Canadian goldenrod. By regulating the synthesis of the endogenous hormone ETH in Canadian goldenrod through AVG, the resistance of ETH in the plant to the pathogenic bacterium SD1 is reduced, thereby enhancing the pathogenicity of SD1 and improving the control efficiency of SD1. Furthermore, this method is environmentally friendly. Using the existing pathogenic bacterium SD1 combined with the ETH inhibitor AVG for integrated biological control of Canadian goldenrod will have significant economic and social benefits, avoiding the need for soil tilling, reducing costs, and greatly increasing the applicability.

Description

Technical Field

[0001] This invention relates to the field of biological control technology, specifically to a method for controlling Canadian goldenrod using AVG in synergy with SD1 bacteria. Background Technology

[0002] Canadian goldenrod (Solidago canadensis L.), a perennial herb belonging to the genus Solidago in the family Asteraceae, is native to North America and is now widely invasive worldwide. As one of the most extensive and damaging invasive alien plants, it is listed in my country's "List of Key Invasive Alien Species under Management." Canadian goldenrod poses a serious threat to my country's biodiversity and ecological balance. This is mainly manifested in two ways: firstly, its invasion of farmland, wasteland, and roadsides, and its rapid expansion, have led to an increase in its ecological status within biological communities. Through allelopathic effects, it inhibits the growth of native plants, reducing local biodiversity and harming the local ecological balance. Secondly, Canadian goldenrod can reproduce both sexually and asexually. It can reproduce by seeds, with a mature plant producing an average of 20,000 seeds, which are small and light, allowing for long-distance dispersal by wind. Simultaneously, its extensive underground rhizomes can rapidly spread and regenerate a large number of new plants, achieving asexual reproduction. After invading unused wasteland, Canadian goldenrod, with its tall stems and extensive underground rhizomes, competes with native plants for nutrients, light, and growing space, leading to reduced crop yields and economic losses.

[0003] Currently, the control of Canadian goldenrod mainly relies on physical and chemical control measures. Physical control primarily involves manual or mechanical removal, which is time-consuming, labor-intensive, and costly. Chemical control agents cause toxic side effects on the soil and ecological environment. Therefore, the development of efficient and environmentally friendly biological control technologies is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for controlling Canadian goldenrod using AVG in synergy with SD1 bacteria.

[0005] The technical solution of the present invention is as follows: A method for controlling Solidago canadensis L. using AVG in combination with SD1 bacteria involves applying a mixture of SD1 bacterial solution and AVG solution to the stem section after cutting the stems of Solidago canadensis L. The SD1 bacterial solution is a biological bacterial solution made using *Sclerotium delphinidin* SD1. The aforementioned *Sclerotium delphinii* SD1, classified as *Sclerotium delphinii*, was deposited on December 28, 2023, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 41076.

[0006] Preferably, the concentration of the AVG solution is 300-500 μmol / L.

[0007] Preferably, the application method is as follows: spray SD1 bacterial solution onto the stem cross-section and then apply AVG solution externally.

[0008] Preferably, the application method is: spraying a mixture of SD1 bacterial solution and AVG solution onto the stem cross-section.

[0009] Preferably, the SD1 bacterial solution is prepared as follows: Inoculate *Sclerotium delphinidin* SD1 onto PDA medium and incubate for 4-5 days. Take the edge of a vigorously growing colony and place it in PDB liquid medium. Incubate on a shaker for 2-3 days until mycelial balls form. Crush the mycelial balls to prepare a uniform mycelial suspension, thus obtaining SD1 bacterial solution.

[0010] Preferably, in step S1, the PDA culture medium has the following weight composition: 200-220 g potato, 20-25 g glucose, 15-20 g agar, 1000 ml distilled water, sterilized at 115-120℃ for 20-25 min, and then cooled for later use.

[0011] Preferably, in step S1, the PDB culture medium has the following weight composition: 300-315 grams of potato, 20-25 grams of glucose, dissolved in water to 1L, autoclaved at 121°C for 20-25 minutes, and cooled to approximately 50-55°C for later use.

[0012] Preferably, the spraying is carried out during or before the flowering period of Canadian goldenrod, and when the outdoor temperature is 30-35°C.

[0013] Preferably, the application rate of the AVG solution is 2.5-5 L / acre / time, applied once every 6-8 days, for a total of 4-6 times.

[0014] The beneficial effects of this invention are: (1) The main component of the present invention, SD1 bacterial solution, has a good control effect on Canadian goldenrod, but it is still far from the ideal control effect. By applying AVG solution, the content of ETH in Canadian goldenrod plants can be reduced, thereby reducing the resistance to SD1 bacterial solution infection, thus enhancing the pathogenicity of SD1 bacterial solution on Canadian goldenrod and achieving stable effect.

[0015] (2) The application of SD1 bacterial solution and AVG in combination with spraying equipment will open up a new control pathway for invasive weeds such as Canadian goldenrod. Currently, there are no reports at home and abroad on using hormone inhibitors as synergists for biological herbicides to control Canadian goldenrod. Therefore, using ETH synthesis inhibitor AVG as a synergist for SD1 bacterial solution in the biological control of Canadian goldenrod will have significant economic and social benefits.

[0016] (3) Applying 500 μmol / L AVG to pathogenic bacterium SD1 will open up a new control pathway for invasive weeds such as Canadian goldenrod. By regulating the synthesis of endogenous hormone ETH in Canadian goldenrod through AVG, the resistance of ETH in Canadian goldenrod to pathogenic bacterium SD1 is reduced, thereby enhancing the pathogenicity of SD1 bacterial solution to Canadian goldenrod and improving the control efficiency of pathogenic bacterium SD1. It is also environmentally friendly. Using the existing pathogenic bacterium SD1 in combination with the ETH inhibitor AVG for integrated biological control of Canadian goldenrod will have extremely significant economic and social benefits. It can avoid the step of tilling the habitat soil, reduce cost input, and greatly expand the scope of application. Attached Figure Description

[0017] Figure 1 Growth performance under different treatments; Figure 2 For the root performance of different treatments, different capital letters in the figure indicate significant differences (p < 0.01). Figure 3 Percentage of SD1-infected lesions at different time periods; Figure 4 The effects of different concentrations of AVG on SD1 infection and growth; Figure 5 The effects of different concentrations of AVG on SD1-infected roots; Figure 6 Percentage of lesions at different times with different concentrations of AVG; Figure 7 The effects of different dosages of AVG on SD1 infection and growth; Figure 8 The effects of different dosages of AVG on SD1-infected roots; Figure 9 The percentage of lesions at different stages of AVG administration at different dosages; different capital letters in the figure indicate significant differences (p < 0.01). Figure 10 For the control effect in wild habitats; Figure 11 For the control of root diseases in wild habitats; Figure 12 The figures show the number of regenerated seedlings and buds at each stage; different capital letters in the figure indicate significant differences (p < 0.01). Figure 13 The control efficacy of each treatment fresh weight imitation and correction strain is shown; different capital letters in the figure indicate significant differences (p < 0.01). Detailed Implementation

[0018] Previous studies in our laboratory have found that the natural pathogenic fungus *Sclerotium delphinii* (SD1) of *Solidago canadensis* has a good lethal effect on *Solidago canadensis*. Therefore, it is urgent to develop a control agent based on SD1 for prevention and control. However, the control effect of applying this agent alone is limited. It is necessary to screen and develop a highly efficient and environmentally friendly synergist to improve the control efficiency of the SD1 control agent.

[0019] Hormones are widely present in plants, playing a regulatory role in various physiological and biochemical processes. Based on their mechanisms of action, they can be divided into two categories: growth hormones and defense hormones. Among defense hormones, typical examples include ethephon (ETH), salicylic acid (SA), and jasmonic acid (JA), which are primarily responsible for responding to and defending against environmental stress. Previous experiments in our laboratory, through hormone regulation analysis of rhizome development and regeneration in *Solidago canadensis* under SD1 bacterium infection stress, found that exogenous addition of 400 μM ETH significantly reduced the pathogenicity of SD1 bacterium to the roots of *Solidago canadensis*. Exogenous addition of other hormones could delay SD1 infection to some extent, but the differences were not statistically significant. Further pot culture experiments with longer incubation periods using different concentrations of exogenous ETH showed that under 300 μM ETH treatment, *Solidago canadensis* rhizomes could develop normally and regenerate new seedlings after 55 days of infection, while those treated with concentrations above 300 μM died before 35 days. Therefore, developing synergists for SD1 control agents targeting ETH inhibitors is the direction for future research.

[0020] ETH inhibitors are divided into ethylene synthesis inhibitors and ethylene receptor inhibitors. The difference lies in that the former inhibits the production of ETH, while the latter blocks the signaling of ethylene. Ethylene synthesis inhibitors mainly include: AVG (aminoethoxyvinylglycine), AOA (aminooxyacetic acid), and Co... 2+ Among them, AVG's mechanism of action is irreversible inhibition of ETH precursor 1-aminocyclopropane-1-carboxylic acid synthase (ACS), blocking the synthesis of ETH precursor 1-aminocyclopropane-1-carboxylic acid (ACC), with good efficacy and high specificity. It can be metabolized and inactivated in plants and has a short residual period in the environment. AOA's mechanism of action is similar to AVG, but its specificity is poor and its inhibitory effect is weaker. Co 2+ The mechanism of action is to replace the copper ion (Cu) at the active site of ACO enzyme. 2+This method inactivates enzymes but poses a risk of heavy metal pollution and has poor environmental friendliness. Ethylene receptor inhibitors mainly include 1-MCP (1-methylcyclopropene) and silver thiosulfate (STS). 1-MCP targets ethylene receptors such as ETR1, and its mechanism of action is to bind to the receptor, thereby blocking ethylene sensing. While this inhibitor has a long-lasting effect, is non-toxic, and has no significant environmental impact, it is a gaseous substance and unstable in the environment, making it unsuitable for field control applications. Silver thiosulfate (STS) works by inactivating Ag... + Cu in the ethylene acceptor + It blocks the binding of ethephon, but easily leaves residual Ag. + It causes environmental pollution, therefore it is not suitable for promotion.

[0021] AVGs play an important role in plant root morphogenesis. In Arabidopsis thaliana, Al 3+ Toxicity rapidly induces ethylene synthesis in root tips, thereby inhibiting root elongation. AVG or Co 2+ Inhibit ethylene synthesis, or Ag + Blocking ethylene signal sensing can significantly alleviate Al 3+ It inhibits root elongation. The most typical application of AVG is to delay fruit ripening, thereby extending the storage and preservation period; it can also reduce fruit drop. Ethylene promotes the development of the abscission layer in the fruit stalk, and AVG treatment can reduce pre-harvest fruit drop, increase fruit set rate, and prolong the fruit's hanging time on the tree. There are almost no reports on the application of AVG in the control of weeds and invasive plants.

[0022] The technical solution adopted in this invention is: a method for effectively controlling Canadian goldenrod by applying SD1 bacterial solution combined with AVG, comprising: Sclerotium delphinii (SD1) is a pathogenic fungal strain discovered and isolated by the patent applicant team from diseased plants of Solidago canadensis in nature in 2023. It is currently deposited at the China General Microbiological Culture Collection Center (CGMCC, address: No. 3, No. 1 Beichen Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, 100101, China), with a deposit date of December 28, 2023 and accession number CGMCC No. 41076. The method of effectively controlling Canadian goldenrod by combining SD1 bacterial solution with AVG involves using a lightweight lawnmower to cut the stems of Canadian goldenrod, spraying SD1 bacterial solution onto the cut surface of the stems, and then applying AVG solution. (1) Preparation of SD1 bacterial suspension: SD1 bacteria were inoculated on PDA medium and cultured in an incubator at 30℃ for 4-5 days. Mycelial cakes were taken from the edge of the vigorously growing colonies using a punch with a diameter of 5-7 mm. The mycelial cakes were placed in PDB liquid medium and cultured on a shaker at 30℃ and 180-200 rpm for 2-3 days. After the formation of mycelial balls, the mycelial balls were crushed to make a uniform mycelial suspension, thus obtaining SD1 bacterial suspension.

[0023] (2) Preparation of AVG solution: Preparation of 2L 500μmol / L AVG solution: Weigh 0.1281 g of solid AVG (HPLC≥98%) using an electronic balance, add an appropriate amount of pure water to the AVG powder and stir well, transfer to a 2L volumetric flask and dilute to the target volume; Preparation of 2L 300μmol / L AVG solution: Weigh 0.0769 g of solid AVG (HPLC≥98%) using an electronic balance, add an appropriate amount of pure water to the AVG powder and stir well, transfer to a 2L volumetric flask and dilute to the target volume.

[0024] Preparation of 2L 100μmol / L AVG solution: Weigh 0.256 g of solid AVG (HPLC≥98%) using an electronic balance, add an appropriate amount of pure water to the AVG powder and stir well, transfer to a 2L volumetric flask and dilute to the target volume.

[0025] (3) The weight composition of the above PDA culture medium is: 200-220g potato, 20-25g glucose, 15-20g agar, 1000ml distilled water. After sterilization at 115-120℃ for 20-25 minutes, it is cooled and ready for use.

[0026] (4) The weight composition of the above PDB medium is as follows: each liter of medium contains 300-315 grams of potato and 20-25 grams of glucose. Add water to dissolve to 1L, autoclave at 121℃ for 20-25 minutes, and cool to about 50-55℃ for later use.

[0027] (5) Furthermore, the spraying device used is the Earth Guardian electric sprayer, which includes an electric pressure pump, a nozzle (3.5 cm in diameter), a spray control switch, and a connecting rod.

[0028] In summary, this invention selects ethylene synthesis inhibitor AVG as its research and development target. Research on the application of AVG in the biocontrol of invasive plants has been pioneered and has achieved good progress. Previous studies have shown that under exogenous ETH addition, inoculation with SD1 pathogen significantly reduces the pathogenicity of *Solidago canadensis*, resulting in strong disease resistance. The key step in the biosynthesis of ETH from methionine is the conversion of S-adenosylmethionine to ACC by ACC synthase (ACS), and AVG can block this process. The technical method of this invention reduces ETH production by exogenously applying AVG, thereby weakening the resistance of *Solidago canadensis* to SD1. Field habitat control experiments show that, under the premise of cutting the aboveground stems, the control effect of applying SD1 bacterial solution in combination with AVG is significantly improved compared to applying SD1 bacterial solution alone, achieving stronger control efficiency in inhibiting rhizome seedling regeneration and root-borne disease and mortality in *Solidago canadensis*. This application systematically studies the method of applying AVG in combination with other agents in terms of concentration and dosage, and derives the optimal AVG application scheme. Studies have found that the optimal growth temperature for SD1 bacteria is 25-30℃. Growth slows significantly at 35℃ and above, and ceases completely at 40℃ and above. Therefore, control measures should be implemented during or before the flowering period of Canadian goldenrod, when the outdoor temperature is 30-35℃. SD1 bacterial solution is sprayed in combination with 500 μmol / L AVG at a rate of 2.5-5 L / acre / application. It is recommended to apply every 7 days for a total of 5 applications. After approximately 40 days, the control efficacy can reach over 90%, with a maximum of approximately 95%, and no rhizome regeneration of seedlings is observed, achieving a zero-recurrence effect.

[0029] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0030] Example 1

[0031] This example compares the differences in pathogenicity of Canadian goldenrod under conditions of SD1 bacterial suspension combined with ETH and AVG.

[0032] To demonstrate the difference in the control effect of SD1 bacterial solution on Canadian goldenrod under the conditions of exogenous addition of ETH and AVG, a pot experiment was conducted. Roots (with 15cm of stem remaining above ground) of normally growing, disease-free plants were collected from the field and brought back to the laboratory, planted in pots, and four treatments were set up: (1) SD1+ETH, with 50 mL of 400μmol / L ETH applied to the stem section every three days after inoculation with SD1 bacterial solution; (2) SD1+AVG, with 50 mL of 300μmol / L AVG applied to the stem section every three days after inoculation with SD1 bacterial solution; (3) SD1, sprayed with SD1 bacterial solution; (4) CK, sprayed with 50 mL of water. Three biological replicates were performed, with 5 pots per replicate, 1 plant per pot, for 24 days. The percentage of infected lesions was measured every 3 days, and the control effect was observed after 24 days. The results are as follows: Figure 1 , Figure 2 As shown.

[0033] The infection rate was significantly enhanced when SD1 bacterial suspension was combined with AVG compared to when it was combined with ETH or when SD1 bacterial suspension was applied alone. Figure 3 Nine days after infection, the infection rates of the aboveground parts of Canadian goldenrod in treatments (1) and (3) were 14.81% and 21.88%, respectively, with no significant difference. However, the infection rate of treatment (2) was 42.21%, which was significantly different from the other treatments. From day 12 to day 24 after infection, the infection rate of treatment (3) was significantly different from that of treatment (1). However, the lesion rate of treatment (2) was always the highest. On day 18 after infection, the lesion rate of treatment (2) was 90.6%, while that of treatments (1) and (3) was 36.98% and 54.47%, respectively. After 24 days of infection, the lesion rate of SD1 bacterial solution combined with AVG reached 100%.

[0034] The roots of the four treatments were excavated, and the results showed that the proportion of root rot and necrosis in the SD1+AVG treatment was significantly higher than that in the SD1+ETH and SD1 treatments. The aboveground fresh weight control efficacy of the SD1+AVG, SD1+ETH, and SD1 treatments was 75.79%, 39.37%, and 63.79%, respectively, and the underground fresh weight control efficacy was 70.79%, 41.73%, and 59.31%, respectively, all reaching highly significant levels.

[0035] In conclusion, the combined application of AVG to SD1 bacterial suspension significantly enhances the infection and pathogenicity of SD1 bacteria in Goldenrod of Canada, while ETH can significantly alleviate the infection of Goldenrod of Canada by SD1 bacteria.

[0036] Example 2

[0037] This example evaluates the pathogenicity of different concentrations of AVG and SD1 bacterial solutions on goldenrod in Canada.

[0038] To evaluate the control effects of SD1 and different concentrations of AVG on Canadian goldenrod, a pot experiment was conducted. Roots (with 15 cm of above-ground stem retained) of healthy, disease-free plants were collected from the wild and planted in pots. Five treatments were set up in the pot experiment: T1, SD1 + 100 μmol / L AVG, followed by external application of 100 μmol / L AVG 50 mL every 3 days after inoculation with SD1 bacterial solution; T2, SD1 + 300 μmol / L AVG, followed by external application of 300 μmol / L AVG 50 mL every 3 days after inoculation with SD1 bacterial solution; T3, SD1 + 500 μmol / L AVG, followed by external application of 500 μmol / L AVG 50 mL every 3 days after inoculation with SD1 bacterial solution; T4, SD1, inoculated with SD1 bacterial solution; T5, CK, sprayed with 50 mL of water. Each treatment was repeated three times, with five pots per replicate, one plant per pot. Treatment lasted 21 days, and the percentage of infected lesions was measured every three days. The control effect was observed after 21 days. Results are as follows: Figure 4 , Figure 5 As shown.

[0039] The lesion percentages in treatments T2 and T3 were 10.10% and 9.02%, respectively, with no significant difference between treatments, but both were significantly higher than those in treatments T1 and T4. Figure 6 After 21 days of treatment, the lesion rate of T2 and T3 treatments reached 100%, which was significantly higher than that of T1 and T4 treatments (72.01% and 72.87%, respectively).

[0040] The control efficacy of the aboveground fresh weight of each treatment was 68.43%, 74.01%, 81.20%, and 50.40%, respectively. The control efficacy of the root fresh weight of each treatment was 36.84%, 49.73%, 57.33%, and 31.76%, respectively. There was no significant difference in the control efficacy between aboveground and underground parts between T3 and T2, but both were significantly different from T1 and T4. The control efficacy of the aboveground and underground parts of treatment T2 was not significantly different from treatments T1 and T3, but was significantly different from treatment T4. The control efficacy of the aboveground part of treatment T1 was significantly different from treatment T4, but there was no significantly different difference in the control efficacy of the underground part between T1 and T4. Treatment T4 showed more obvious rhizome necrosis in *Solidago canadensis*.

[0041] Therefore, the T3 treatment followed by inoculation with SD1 bacterial suspension and application of 500 μmol / L AVG resulted in the strongest pathogenicity and the best control effect against Canadian goldenrod.

[0042] Example 3

[0043] This example evaluates the pathogenicity of Canadian goldenrod by applying different amounts of AVG combined with SD1 bacterial solution.

[0044] A pot experiment was conducted to evaluate the control effects of SD1 bacterial solution and different dosages of AVG on *Solidago canadensis*. Roots (with 15 cm of the above-ground stem retained) from healthy, disease-free mature *Solidago canadensis* plants were collected from the wild and planted in pots. Six treatments were set up in the pot experiment: T1, inoculation with SD1 bacterial solution followed by topical application of 25 mL of 500 μmol / L AVG every 3 days; T2, inoculation with SD1 bacterial solution followed by topical application of 50 mL of 500 μmol / L AVG every 3 days; T3, inoculation with SD1 bacterial solution followed by topical application of 75 mL of 500 μmol / L AVG every 3 days; T4, inoculation with SD1 bacterial solution followed by topical application of 100 mL of 500 μmol / L AVG every 3 days; T5, SD1, inoculation with SD1 bacterial solution; T6, CK, topical application of 50 mL of water every 3 days. Each treatment was repeated three times, with five pots per replicate, one plant per pot. Treatment lasted 24 days, and the percentage of infected lesions was measured every three days. The control effect was observed after 24 days. Results are as follows: Figure 7 , Figure 8 As shown.

[0045] Six days after treatment, the lesion percentages of T2, T3, and T4 treatments were 30.78%, 27.95%, and 28.63%, respectively. There were no significant differences among the three treatments, but all were highly significant compared to T1, T5, and T6. Significant differences also existed between T1 and T5 / T6. Figure 9 After 9-18 days of treatment, there was no significant difference between T1 and T5. After 21 days, the lesion proportions of T2, T3, and T4 treatments all reached 100%, showing a highly significant difference compared to other treatments. The lesion proportions of T1 and T5 were 70.67% and 63.59%, respectively, and were also highly significant.

[0046] The aboveground fresh weight control efficacy for each treatment was 59.03%, 68.22%, 71.42%, 82.30%, and 52.16%, respectively. The aboveground fresh weight control efficacy of treatment T4 (82.30%) was highly significant compared to the other treatments. The underground fresh weight control efficacy was 43.47%, 58.39%, 64.91%, 70.08%, and 40.80%, respectively. The underground fresh weight control efficacy of treatments T3 and T4 was not significantly different from the other treatments, but the differences were significant.

[0047] Therefore, using treatment T4: 100 ml of 500 μmol / L AVG combined with SD1 can enhance the infection of Canadian goldenrod by SD1 bacterial solution, thereby achieving the purpose of preventing mortality.

[0048] Example 4

[0049] This example demonstrates a field control experiment using SD1 bacterial inoculation combined with AVG.

[0050] In July 2025, Canadian goldenrod invaded an area in the suburbs of Nanchang (invasion density > 40 plants / m²). 2 A field demonstration trial of the SD1 bacterial solution combined with AVG application according to the present invention was conducted. The demonstration trial included five treatments: Treatment 1 involved cutting the above-ground stems; Treatment 2 involved inoculation with SD1 bacterial solution (2.5 L / mu); Treatment 3 involved SD1 bacterial solution + water + 500 μmol / L AVG, with a volume ratio of SD1 bacterial solution, water, and 500 μmol / L AVG of 1:1:1 (7.5 L / mu); Treatment 4 involved SD1 bacterial solution + water + 500 μmol / L AVG, with a volume ratio of SD1 bacterial solution, water, and 500 μmol / L AVG of 1:1:2 (10 L / mu); Treatment 5 involved SD1 bacterial solution + 500 μmol / L AVG, with a volume ratio of SD1 bacterial solution and 500 μmol / L AVG of 1:1 (5 L / mu); Treatment 1 served as the control. Each treatment was replicated three times, with each plot measuring 1 m. 2 During the treatment, treatment 2 involved spraying SD1 bacterial solution directly after mowing; treatments 3 and 4 involved spraying SD1 bacterial solution mixed with water first, followed by external application of AVG solution; treatment 5 involved spraying a mixture of AVG solution and SD1 bacterial solution directly. Each treatment was observed and treated with the same volume and concentration of AVG solution every 7 days. A total of 5 observations and applications were conducted during the experiment. Root samples were dug up after 40 days to observe the control effect, examining the control efficacy, the regeneration of new shoots and seedlings, and photographing the control effect. Results are as follows: Figure 10 , Figure 11 As shown.

[0051] The results showed that the mortality rate of the single application of SD1 bacterial solution was significantly lower than that of the combined application of AVG (Table 1). After day 21, the number of regenerated shoots in treatments two, three, four, and five was significantly lower than that in the control mowing treatment. After day 40, the number of regenerated shoots in treatments four and five was further significantly lower than that in treatments two and three. From day 28 onwards, the number of regenerated seedlings in treatments two, three, four, and five was significantly higher than that in treatment one, with treatments four and five showing even stronger performance. After day 21, the number of regenerated seedlings began to be significantly lower than that in other treatments. Figure 12 The aboveground fresh weight control efficacy of each treatment was 57.66%, 71.52%, 76.15%, and 76.84%, respectively. Treatments three, four, and five showed comparable efficacy, and all were significantly higher than treatment two. Root excavation revealed root fresh weight control efficacy of 45.10%, 77.63%, 61.36%, and 73.64%, respectively. Except for treatment four, treatments three and five showed comparable efficacy, and all were significantly higher than treatment two. Corrected plant control efficacy of each treatment was 65.12%, 87.60%, 94.57%, and 91.47%, respectively. Treatments three, four, and five showed comparable efficacy, and all were significantly higher than treatment two. Figure 13Therefore, treatments three, four, and five have similar preventive and control effects.

[0052] Table 1. Mortality rates of Canadian goldenrod in different treatments Note: Different capital letters indicate significant differences (p < 0.01).

[0053] like Figure 11 As shown, the degree of root necrosis and the condition of regenerated seedlings were observed after 40 days of treatment. The root system of the mowing treatment produced the most seedlings and a large number of buds / seedlings. The roots of the SD1 treatment alone had some necrosis, but the mortality rate was low, and some rhizomes sprouted seedlings. The treatment with SD1 bacterial solution mixed with different volumes of AVG had good effects, and the rhizomes were completely necrotic.

[0054] Through comprehensive analysis of root mortality rate, number of regenerated buds, number of regenerated seedlings, fresh weight efficacy against both imitation and corrected plants, and the degree of root mortality after treatment, treatments three, four, and five showed comparable and strongest control efficiency against Canadian goldenrod. This indicates that the combined application of AVG enhanced the infection efficiency and control effect of SD1 bacterial solution against Canadian goldenrod. In conclusion, the combined application of SD1 bacterial solution and AVG is highly efficient in controlling Canadian goldenrod in the field, completely killing the stubborn roots with almost no regeneration of buds.

[0055] In summary, the SD1 bacterial solution of this invention can be mass-produced and, when combined with 500 μmol / L AVG, can be used for highly effective control of Canadian goldenrod. The treatment with a volume ratio of SD1 bacterial solution + water + 500 μmol / L AVG of 1:1:2 (10 L / acre) showed the best control effect, achieving a control efficacy of approximately 95% in field-corrected plants. The next best control efficacy was achieved with a volume ratio of SD1 bacterial solution + 500 μmol / L AVG of 1:1 (5 L / acre) at approximately 92%, and with a volume ratio of SD1 bacterial solution + water + 500 μmol / L AVG of 1:1:1 (7.5 L / acre) at approximately 88%. The study in Case 4 revealed that the effectiveness of this technology in controlling Canadian goldenrod was independent of the application method of 500 μmol / L AVG. Considering economic costs, the preferred control formula is SD1 bacterial solution + 500 μmol / L AVG (5 L / mu). The next best formulas are SD1 bacterial solution + water + 500 μmol / L AVG in a volume ratio of 1:1:2 (10 L / mu) and SD1 bacterial solution + water + 500 μmol / L AVG in a volume ratio of 1:1:1 (7.5 L / mu).

[0056] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A method for controlling Canadian goldenrod (Solidago canadensis L.) using AVG in synergy with SD1 bacteria, characterized in that, After cutting the stems of Canadian goldenrod, SD1 bacterial solution and AVG solution were applied to the stem cross-section. The SD1 bacterial solution is a biological bacterial solution made using *Sclerotium delphinidin* SD1. The aforementioned *Sclerotium delphinii* SD1, classified as *Sclerotium delphinii*, was deposited on December 28, 2023, at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 41076.

2. The method according to claim 1, characterized in that, The concentration of the AVG solution is 300-500 μmol / L.

3. The method according to claim 1, characterized in that, The application method is as follows: spray SD1 bacterial solution onto the stem section and then apply AVG solution externally.

4. The method according to claim 1, characterized in that, The application method is as follows: spray a mixture of SD1 bacterial solution and AVG solution onto the stem cross-section.

5. The method according to claim 1, characterized in that, The method for preparing the SD1 bacterial culture is as follows: Inoculate *Sclerotium delphinidin* SD1 onto PDA medium and incubate for 4-5 days. Take the edge of a vigorously growing colony and place it in PDB liquid medium. Incubate on a shaker for 2-3 days until mycelial balls form. Crush the mycelial balls to prepare a uniform mycelial suspension, thus obtaining SD1 bacterial solution.

6. The method according to claim 5, characterized in that, In step S1, the PDA culture medium consists of the following weight components: 200-220g potato, 20-25g glucose, 15-20g agar, and 1000ml distilled water. After sterilization at 115-120℃ for 20-25min, the medium is cooled for later use.

7. The method according to claim 5, characterized in that, In step S1, the PDB culture medium consists of the following weight components: 300-315 grams of potato, 20-25 grams of glucose, dissolved in water to 1L, autoclaved at 121°C for 20-25 minutes, and cooled to approximately 50-55°C for later use.

8. The method according to claim 1, characterized in that, The spraying is specifically carried out during or before the flowering period of Canadian goldenrod, when the outdoor temperature is 30-35℃.

9. The application according to claim 1, characterized in that, The AVG solution is applied at a rate of 2.5-5 L / acre / time, once every 6-8 days, for a total of 4-6 times.

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