Trichoderma harzianum and microbial agent for preventing and treating root rot of pasture grasses and application thereof
By using microbial agents made from Trichoderma harzianum to control forage root rot, the serious impact of forage root rot has been solved, achieving effective disease control and sustainable agricultural development.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF PLANT PROTECTION CHINESE ACAD OF AGRI SCI
- Filing Date
- 2025-03-04
- Publication Date
- 2026-05-22
AI Technical Summary
Forage root rot seriously affects forage growth and quality. Existing technologies are insufficient for its effective prevention and control, and modern management methods are lacking.
Microbial inoculants made from Trichoderma harzianum (CGMCC No. 41718) were applied to the soil around the roots of forage grasses to prevent root rot.
Trichoderma harzianum is highly specific for root rot, safe and non-toxic, and harmless to pasture growth, meeting the needs of sustainable agricultural development and significantly reducing the incidence of root rot.
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Figure CN119709436B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of microbial technology, particularly to the field of biocontrol microbial technology, specifically to a Trichoderma harzianum for controlling root rot in forage grasses and a microbial agent thereof, and their application. Background Technology
[0002] Accelerated urbanization and economic development have led to the large-scale occupation and destruction of grasslands, impacting forage production. Simultaneously, forage production technology remains relatively backward, lacking modern management methods and technical support, making it difficult to meet the demand for efficient, high-quality forage. Natural grasslands primarily provide forage for livestock such as cattle, sheep, horses, camels, and yaks; therefore, reducing harmful substances in natural grasslands is a crucial indicator for developing forage production technology.
[0003] Diseases and pests are rampant in forage crops, with root rot being particularly prevalent in summer, reaching 30-50% in some pastures, severely impacting forage growth and quality. To improve natural pasture management techniques and to adhere to green, environmentally friendly, and sustainable agricultural practices, utilizing biological control agents to prevent and control root rot in natural pastures is crucial for both present and future prevention and control of this disease. Summary of the Invention
[0004] The purpose of this disclosure is to provide a Trichoderma harzianum and microbial agent for the prevention and control of root rot in forage grasses.
[0005] To achieve the above objectives, the first aspect of this disclosure provides a Trichoderma harzianum for controlling root rot in forage grasses, the Trichoderma harzianum being classified as Trichoderma harzianum. Trichoderma harzianum The preservation number of the Trichoderma harzianum is CGMCC No. 41718.
[0006] Optionally, the *Trichoderma harzianum* rpb The nucleotide sequence of gene 2 is shown in SEQ ID NO.1; the Trichoderma harzianum... tef The nucleotide sequence of the 1α gene is shown in SEQ ID NO.2; the nucleotide sequence of the ITS gene of the Trichoderma harzianum is shown in SEQ ID NO.3.
[0007] Optionally, the Trichoderma harzianum is circular in shape with regular edges, the front of the colony is green with green aerial hyphae and green spores, and the back of the colony is grayish-white.
[0008] The second aspect of this disclosure provides a microbial inoculant containing Trichoderma harzianum with accession number CGMCC No. 41718 and a culture medium.
[0009] Optionally, the viable count of *Trichoderma harzianum* with accession number CGMCC No. 41718 in each gram of the microbial inoculant is 10. 8 -10 11 CFU.
[0010] Optionally, the culture medium is potato dextrose agar medium and potato dextrose medium.
[0011] The third aspect of this disclosure provides the application of Trichoderma harzianum described in the first aspect or the microbial agents described in the second aspect in the prevention and control of root rot in pasture.
[0012] Optionally, the forage grass is selected from one or more of the following: orchardgrass, chardgrass, Chinese fescue, and icegrass.
[0013] The fourth aspect of this disclosure provides a method for preventing root rot in forage grass, the method comprising: applying the Trichoderma harzianum described in the first aspect or the microbial agent described in the second aspect to the soil around the roots of the forage grass.
[0014] Optionally, the dosage of Trichoderma harzianum is 10. 8 -10 11 CFU / m 2 .
[0015] Through the above technical solution, this disclosure provides a Trichoderma harzianum fungus and a microbial inoculant for controlling root rot in forage grasses. This Trichoderma harzianum fungus exhibits good efficacy in controlling root rot in forage grasses. Furthermore, it is safe and non-toxic to humans and animals, and possesses strong specificity for root rot, meeting the needs of sustainable agricultural development.
[0016] Other features and advantages of this disclosure will be described in detail in the following detailed description section.
[0017] Preservation of biological materials
[0018] The *Trichoderma harzianum* disclosed herein is a pure culture isolated by the inventors from soil in Koktokay, Fuyun County, Altay Prefecture, Xinjiang. Its accession number is CGMCC No. 41718, the deposit date is December 13, 2024, and the depositary institution is the China General Microbiological Culture Collection Center, located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. Its classification name is *Trichoderma harzianum*. Trichoderma harzianum . Attached Figure Description
[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:
[0020] Figure 1 This is a colony morphology diagram of Trichoderma published in this paper. Detailed Implementation
[0021] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0022] The inventors of this disclosure isolated a pure culture from the soil of Koktokay, Fuyun County, Altay Prefecture, Xinjiang. The fungus was identified as belonging to the genus Trichoderma. Trichoderma It was named Trichoderma harzianum. Trichoderma harzianum This strain has been deposited at the China General Microbiological Culture Collection Center (CGMCC), the designated depository of the State Intellectual Property Office, on December 13, 2024, with accession number CGMCC No. 41718.
[0023] The first aspect of this disclosure provides a Trichoderma harzianum for controlling root rot in forage grasses, the Trichoderma harzianum being classified as Trichoderma harzianum. Trichoderma harzianum The preservation number of the Trichoderma harzianum is CGMCC No. 41718.
[0024] The *Trichoderma harzianum* disclosed herein can survive and grow in conventional bacterial culture media. As described above, the *Trichoderma harzianum* strain disclosed herein is a biocontrol strain, particularly effective in controlling root rot in forage grasses.
[0025] According to this disclosure, the *Trichoderma harzianum* rpb The nucleotide sequence of gene 2 is shown in SEQ ID NO.1; the Trichoderma harzianum... tef The nucleotide sequence of the 1α gene is shown in SEQ ID NO.2; the nucleotide sequence of the ITS gene of the Trichoderma harzianum is shown in SEQ ID NO.3.
[0026] In one embodiment of this disclosure, such as Figure 1 As shown, the *Trichoderma harzianum* is circular in shape with regular edges. The colony surface is green, with green aerial hyphae and green spores, while the reverse side is grayish-white. Furthermore, the spore yield is high.
[0027] The second aspect of this disclosure provides a microbial inoculant containing Trichoderma harzianum with accession number CGMCC No. 41718 and a culture medium.
[0028] The viable count of *Trichoderma harzianum* in the microbial inoculant can vary within a wide range. In one embodiment of this disclosure, the viable count of *Trichoderma harzianum* with accession number CGMCC No. 41718 is 10 per gram of the microbial inoculant.8 -10 11 CFU.
[0029] According to this disclosure, the culture medium is potato dextrose agar (PDA) and potato dextrose agar (PD).
[0030] Optionally, the potato dextrose agar solid medium (PDA) is prepared as follows: 20g of peeled potatoes are boiled for 20 minutes to extract the juice. The juice is then mixed with 2g of glucose, 1.5g of agar, and water to make 100mL, with a pH of 6.5-7.0. The mixture is then poured into two Erlenmeyer flasks, each containing 50mL, and sterilized to form slant or plate. The potato dextrose liquid medium (PD) is prepared as follows: 20g of peeled potatoes are boiled for 20 minutes to extract the juice. The juice is then mixed with 2g of glucose and water to make 100mL, with a pH of 6.5-7.0. The mixture is then poured into two Erlenmeyer flasks, each containing 50mL, and sterilized.
[0031] Alternatively, the above-mentioned culture media can be sterilized using conventional sterilization methods, such as sterilizing at 115-125°C and 1.5-2 atmospheres for 10-30 minutes.
[0032] The preparation method of the microbial inoculant may include: inoculating *Trichoderma harzianum* with preservation number CGMCC No. 41718 into potato dextrose agar (PDA) solid medium and incubating at 25°C for 7 days; then taking 3-4 mycelial blocks and adding them to a seed bottle; and incubating at 25°C and 180 rpm for 48 hours to prepare a seed culture for later use. The seed culture is then added to a seed fermentation tank at a volume ratio of 1:150 for further cultivation, and then added to a fermentation tank containing chlamydospore fermentation medium (containing 2.5% starch, 1.5% yeast powder, 5.0% corn steep liquor, 0.4% CaCO3, 0.01% ZnSO4, and 0.03% MgSO4 by weight) at a volume ratio of 1:20. The medium is incubated at 28°C for 5 days until 90% of the mycelia have formed chlamydospores, yielding a chlamydospore fermentation broth. The fermentation broth is then adsorbed using diatomaceous earth, centrifuged or filtered through a plate and frame filter, and dried to form a wettable powder.
[0033] In a preferred embodiment, the viable count of *Trichoderma* fungus with accession number CGMCC No. 41718 in each gram of the obtained microbial inoculant can be 10. 8 -10 11 CFU, preferably 10 9 -10 10CFU. During the cultivation process, the viable cell count can be tested using conventional methods, such as hemocytocyte count or OD value observation, to determine the concentration of viable cells. The cultured bacterial solution can be used directly as a microbial inoculant. Preferably, the bacterial solution is further processed into a more convenient storage formulation of the microbial inoculant through steps including aseptic filtration and freeze-drying. There are no particular restrictions on the cultivation conditions for the strain; commonly used conditions in Trichoderma cultivation can be applied, such as shaking culture at a temperature of 25-30°C for 1-2 days.
[0034] The third aspect of this disclosure provides the application of Trichoderma harzianum described in the first aspect or the microbial agents described in the second aspect in the prevention and control of root rot in pasture.
[0035] In one embodiment of this disclosure, the forage grass is a natural forage grass, for example, selected from one or more of orchardgrass, chardgrass, Chinese fescue and ice grass.
[0036] The fourth aspect of this disclosure provides a method for preventing root rot in forage grass, the method comprising: applying the Trichoderma harzianum described in the first aspect or the microbial agent described in the second aspect to the soil around the roots of the forage grass.
[0037] In one embodiment of this disclosure, the amount of Trichoderma harzianum used is 10. 8 -10 11 CFU / m 2 .
[0038] In the above embodiments, the application can be carried out in a manner commonly used by those skilled in the art, such as spraying, root irrigation, or mixing with soil.
[0039] The present invention will be further described in detail below with reference to the embodiments, but the scope of the present invention is not limited to the following embodiments.
[0040] The method for preparing potato dextrose agar (PDA) solid medium used in this embodiment is as follows: Take 20g of peeled potatoes, boil for 20 minutes to extract the juice, add 2g of glucose and 1.5g of agar to the juice, add water to 100mL, the pH is 6.5-7.0, put it into 2 Erlenmeyer flasks, 50mL each, sterilize and make slant or plate.
[0041] The fermenter formula for the thick-walled spore fermentation medium is as follows: by weight, it contains 2.5% starch, 1.5% yeast powder, 5.0% corn steep liquor, 0.4% CaCO3, 0.01% ZnSO4, and 0.03% MgSO4.
[0042] Example 1
[0043] This embodiment illustrates the isolation and purification of Trichoderma harzianum according to this disclosure.
[0044] I. Soil collection and treatment.
[0045] Soil samples were collected in Koktokay, Fuyun County, Altay Prefecture, Xinjiang. The collection method was as follows: at each sampling point, 10m of vegetation was observed... 2 Within the quadrats, the five-point diagonal sampling method was used for soil collection. During sampling, after removing the top 2cm of soil, soil around the plant roots was collected, and soil from the rhizosphere of the host plant at a depth of 20cm was taken. After mixing, 200g of the soil was placed in a sterilized resealable bag, brought back to the laboratory, and recorded (including: collection location, latitude and longitude, altitude, and cover vegetation). The samples were stored at 4℃.
[0046] II. Isolation and purification of strain MCGF-1.
[0047] 1. Soil sample processing:
[0048] Take 10g of cleaned soil and add it to 90mL of sterile water. Shake well to obtain a mixture. Pipette 1mL of this mixture into a test tube containing 9mL of sterile water and mix well to obtain a dilution of 10. -1 The diluted solution was prepared sequentially using the 10-fold dilution method to obtain 10... -2 10 -3 Diluents at different dilution concentrations. Take 10... -3 100 μL of the soil sample dilution was spread onto a PDA medium plate, and then spread evenly with a sterile spreader. This process was repeated three times on the PDA medium. The plate was incubated in a mold incubator at 28°C. After 10 days, the fungal colonies were observed. The suspected Trichoderma colonies appearing on the plate were counted, and further purification was carried out.
[0049] 2. Culture and purification of bacterial strains:
[0050] Suspected Trichoderma harzianum strains were picked from agar plates and transferred to PDA medium for multiple rounds of purification culture until the strain was completely purified, with a total culture period of more than three weeks. The purified Trichoderma harzianum strains were temporarily stored on PDA slants at 4°C, while three aliquots were simultaneously inoculated into 30% glycerol tubes and stored in an ultra-low temperature freezer. Depending on the growth requirements, the strains were cultured in appropriate quantities and at appropriate times, with each Trichoderma strain containing 10... 8 The amount of CFU was applied to the soil around the roots of the forage grass for 40 days by root irrigation. The results showed that strain MCGF-1 was effective in preventing and controlling forage grass root rot (see Example 2 for details). Therefore, strain MCGF-1 was identified as follows.
[0051] III. Identification of strain MCGF-1.
[0052] 1. Morphological identification:
[0053] Take a mycelial disc of the same diameter from the edge of a purified colony of strain MCGF-1 and place it in the center of a medium (PDA medium). Observe the growth rate of the strain, its growth status during the culture process, colony color, mycelial morphology, and other characteristics. The results are as follows: Figure 1 As shown.
[0054] The results showed that after culturing at 27°C for 7 days, the MCGF-1 strain isolated and purified by the above steps exhibited radially circular colonies with regular edges. The front of the colonies was green, with green aerial hyphae and green spores, and the aerial hyphae extended in all directions. The back of the colonies was grayish-white.
[0055] 2. Molecular biological identification:
[0056] DNA extraction: Scrape an appropriate amount of hyphae of strain MCGF-1 and place them in a sterile centrifuge tube. Incubate at 0°C for at least 30 minutes. Before starting DNA extraction, place one steel ball in each centrifuge tube and oscillate at 50 Hz for 3 minutes using a freeze-thaw cell disruptor. After extraction, follow the operating steps of the Fungal Genome Extraction Kit (Adley Fungal DNA Rapid Extraction Kit) sequentially. Collect the DNA in a new centrifuge tube and determine the concentration using a micro spectrophotometer. Once the DNA reaches the acceptable level, PCR amplification can be performed.
[0057] PCR amplification: for the internal transcribed spacer (ITS) of ribosomal RNA-encoding genes, and translation elongation factor 1α (... tef The fourth and fifth introns and most of the last exon of 1α), and rpb The 2 (RNA polymerase second subunit) gene was amplified, and the primer sequences are shown in Table 1:
[0058] Table 1
[0059]
[0060] In the primers mentioned above, Y is T or C; R is G or A; W is A or T; and S is C or G.
[0061] PCR reaction system: 2 μL each of upstream and downstream primers, 25 μL of Taq PCR StarMix (with Loading Dye), 1 μL of bacterial DNA template, 20 μL of ddH2O, and a total system volume of 50 μL.
[0062] PCR amplification program for RPB and TEF genes: 95℃ for 3 min, 95℃ for 30 s, 52℃ for 30 s, 72℃ for 1 min (35 cycles), 72℃ for 5 min.
[0063] PCR amplification program for the ITS sequence: 95℃ for 3 min, 95℃ for 30 s, 50℃ for 30 s, 72℃ for 1 min (35 cycles), 72℃ for 5 min.
[0064] PCR product detection and sequencing: Prepare a 1% agarose gel, add 6 μL of DNA marker to the first or last well, and add 6 μL of PCR product to the other wells. Electrophoresis is performed at 125V for 30 min, and the bands are observed and images are acquired using a gel imaging system.
[0065] After successful sample amplification, it was sent to the company (Qingke Biotechnology) for sequencing, and the strain NY-1 was detected. rpb 2. The sequence is shown in SEQ ID NO.1. tef The 1α sequence is shown in SEQ ID NO.2, and the ITS sequence is shown in SEQ ID NO.3.
[0066] According to the latest criteria for Trichoderma species classification proposed by Cai and Druzhinina, the following must be met simultaneously: rpb 2≥99%, tef To be identified as a Trichoderma species, three conditions must be met: α ≥ 97%, ITS ≥ 76%. rpb 2 genes, tef1 The α gene and ITS region sequences were compared using NCBI Blast (https: / / blast.ncbi.nlm.nih.gov / Blast.cg), and strain MCGF-1 was found to have... rpb The similarity of gene 2 to *Trichoderma harzianum* is 99.02-99.40%, exceeding 99%, and the strain MCGF-1... tef The 1α gene shares 97-99.91% similarity with *Trichoderma harzianum*, and the ITS sequence of strain MCGF-1 shares 99.20% similarity with *Trichoderma harzianum*. Therefore, we confirm that the classification of the *Trichoderma* species is *Trichoderma harzianum*.
[0067] Based on the above morphological and molecular biological identification, strain MCGF-1 was identified as *Trichoderma*. Trichoderma harzianum This strain was deposited on December 13, 2024, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 41718.
[0068] Example 2
[0069] This example illustrates the preparation of microbial inoculants.
[0070] Trichoderma harzianum with preservation number CGMCC No. 41718 was inoculated into potato dextrose agar (PDA) solid medium and incubated at 25°C for 7 days. Three to four mycelial blocks were then added to a seed bottle. The mixture was incubated at 25°C and 180 rpm for 48 hours to prepare a seed culture. The seed culture was added to a seed fermentation tank at a volume ratio of 1:150 and then added to a fermentation tank containing chlamydospore fermentation medium (containing 2.5% starch, 1.5% yeast extract, 5.0% corn steep liquor, 0.4% CaCO3, 0.01% ZnSO4, and 0.03% MgSO4 by weight) at a volume ratio of 1:20. The mixture was incubated at 28°C for 5 days until 90% of the mycelia had formed chlamydospores, yielding the chlamydospore fermentation broth. The fermentation broth was then adsorbed using diatomaceous earth, centrifuged or filtered through a plate and frame filter, and dried to form a wettable powder. The resulting wettable powder is the microbial inoculant of this embodiment, and the viable count of Trichoderma harzianum in this microbial inoculant is 5 × 10⁻⁶. 9 CFU / g.
[0071] Comparative Example 1
[0072] A strain of *Trichoderma harzianum* (CGMCC No. 40020), purchased from the China Center for Type Culture Collection, was inoculated into potato dextrose agar (PDA) medium and incubated at 25°C for 7 days. Three to four mycelial blocks were then added to a seed bottle. The mixture was shaken at 25°C and 180 rpm for 48 hours to prepare a seed culture. The seed culture was then added to a seed fermentation tank at a volume ratio of 1:150, followed by a 1:20 volume ratio addition to a fermentation tank containing chlamydospore fermentation medium. The mixture was incubated at 28°C for 5 days until 90% of the mycelia formed chlamydospores, yielding the chlamydospore fermentation broth. The broth was then adsorbed with diatomaceous earth, centrifuged or filtered through a plate and frame filter, and dried to form a wettable powder. This wettable powder is the microbial inoculum for this comparative example, containing 5 × 10⁻⁶ viable *Trichoderma harzianum* cells. 9 CFU / g.
[0073] Comparative Examples 2-7
[0074] Six *Trichoderma harzianum* strains isolated together with *Trichoderma harzianum* with accession number CGMCC No. 41718 of this application were inoculated into potato dextrose agar (PDA) solid medium and incubated at 25°C for 7 days. Three to four mycelial blocks were then added to seed bottles. The culture was prepared by shaking at 25°C and 180 rpm for 48 hours to obtain a seed culture. The seed culture was added to a seed fermentation tank at a volume ratio of 1:150 and then added to a fermentation tank containing chlamydospore fermentation medium at a volume ratio of 1:20. The culture was incubated at 28°C for 5 days until 90% of the mycelia formed chlamydospores, yielding a chlamydospore fermentation broth. The fermentation broth was then adsorbed with diatomaceous earth, centrifuged or filtered through a plate and frame filter, and dried to form a wettable powder, resulting in a viable count of 5 × 10⁻⁶ *Trichoderma harzianum*. 9 The wettable powder obtained by measuring CFU / g is the microbial agent of this comparative example.
[0075] Test Example 1
[0076] This test example illustrates that the strain MCGF-1 disclosed herein can control root rot in forage grasses. Tests were conducted using wettable powders from Examples 2 and Comparative Examples 1-7, respectively.
[0077] The specific method is as follows:
[0078] Preparation of root rot pathogen suspension: The root rot pathogen was isolated from alfalfa plants showing root rot and cultured in LB medium until the bacterial density reached OD. 600 The value is 2. The obtained bacterial solution is diluted 2000 times to obtain the pathogenic bacterial solution.
[0079] Experiments were conducted using wettable powders from Examples 2 and Comparative Examples 1-7, respectively. Three natural grasslands of the same species and with consistent growth were selected, each 2m² in size. 2 The experimental group received wettable powder treatment at a rate of 2 g / m³. 2 (i.e. 10 8 CFU / m 2 The control group did not receive wettable powder treatment; all other conditions, including field management, were the same. 25 days after wettable powder application, both the experimental and control groups received 2 L / m³ of wettable powder. 2 After applying the pathogenic bacterial solution, the control effect on forage root rot was observed between the experimental group and the control group 30 days later. A control group without the bacterial solution was set up.
[0080] The effectiveness of Trichoderma harzianum in controlling root rot in forage grasses was characterized by relative control effect and disease index.
[0081] Relative prevention and control effect (%) = (Control disease index - Treatment disease index) / Control disease index.
[0082] The disease severity index is a comprehensive indicator that takes into account both the incidence and severity of the disease. When the severity is represented by a graded representative value, the disease severity index = 100 × ∑ (number of disease roots at each grade × representative value at each grade) / (total number of disease roots investigated × highest grade representative value).
[0083] Among them, level 0 represents a healthy plant;
[0084] Grade 1: Lesions appear on the main root or localized parts of the rhizome, with the lesion area less than 10%;
[0085] Grade 2 is characterized by 10%-30% of the main root or rhizome showing contiguous lesions;
[0086] Grade 3 is characterized by 30%-50% of the main root and rhizome showing lesions;
[0087] Grade 4 is characterized by lesions appearing on 50%-70% of the main root and rhizome.
[0088] Level 5 is characterized by 70%-90% of the main root and rhizome showing lesions;
[0089] Level 6 indicates that more than 90% of the main root and rhizome have lesions.
[0090] The results are shown in Table 2.
[0091] Table 2
[0092]
[0093] As shown in Table 2, the disease index of forage root rot was lowest in Example 2 and Comparative Examples 1-7, and Example 2 had the highest relative efficacy, with a relative control effect of 66%. Therefore, the *Trichoderma harzianum* with accession number CGMCC No. 41718 disclosed herein can control forage root rot, and the *Trichoderma harzianum* disclosed herein has a control effect on forage root rot.
[0094] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0095] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0096] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. The application of Trichoderma harzianum or a microbial inoculant in the control of forage root rot, characterized in that, The fungus *Trichoderma harzianum* is classified as *Trichoderma harzianum*. Trichodermaharzianum The preservation number of the *Trichoderma harzianum* is CGMCC No. 41718. The nucleotide sequence of the rpb2 gene of *Trichoderma harzianum* is shown in SEQ ID NO. 1; The nucleotide sequence of the tef1α gene of *Trichoderma harzianum* is shown in SEQ ID NO. 2; The nucleotide sequence of the ITS gene of *Trichoderma harzianum* is shown in SEQ ID NO. 3; The microbial inoculant contains Trichoderma harzianum with preservation number CGMCC No. 41718 and a culture medium; The forage grass is selected from one or more of the following: orchardgrass, chardgrass, Chinese sheep fescue and ice grass; Of which, per gram of the microbial inoculant, the viable count of *Trichoderma harzianum* with preservation number CGMCCNo.41718 is [missing information]. - CFU.
2. The application according to claim 1, wherein, The Trichoderma harzianum is round in shape with regular edges. The front of the colony is green with green aerial hyphae and green spores, while the back of the colony is grayish-white.
3. The microbial agent according to claim 1, wherein, The culture media are potato dextrose agar medium and potato dextrose medium.
4. A method for preventing and controlling root rot in forage grass, characterized in that, The method includes applying the Trichoderma harzianum or microbial agent as described in claim 1 to the soil around the roots of the forage grass.
5. The method according to claim 4, wherein, The dosage of Trichoderma harzianum is as follows: - CFU / .