A seed treatment agent containing metalaxyl-m, ipconazole and thiamethoxam and its use

Abstract

The application belongs to the field of pesticide preparation, and particularly relates to a seed treatment suspension containing mefenoxam, ipconazole and thiomethon, and application thereof, which comprises the following components: mefenoxam 1%-3%, ipconazole 1%-5%, thiomethon 1%-3%, dispersing agent 5%-12%, wetting agent 2%-5%, film forming agent 3%-8%, thickening agent 0.15%-0.3%, antifreezing agent 2%-6%, preservative 0.1%-0.5%, defoaming agent 0.3%-1.0%, warning color 3%-12%, and the rest is deionized water. The seed treatment agent can effectively prevent and control the occurrence of rice seedling blight and peanut root rot.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulation technology, specifically to a ternary compound seed treatment agent, which is particularly suitable for the prevention and control of rice bakanae disease and peanut root rot. Background Technology

[0002] Metalaxyl-m, chemical formula: C 15 H 21 NO4 is a highly effective, low-toxicity, broad-spectrum systemic aniline fungicide with strong bactericidal and fungal growth-inhibiting capabilities. Its mechanism of action primarily involves inhibiting RNA biosynthesis, thereby preventing fungal sporulation and inhibiting mycelial growth, ultimately leading to pathogen death. It exhibits excellent control effects against seed-borne and soil-borne diseases caused by oomycetes, making it suitable for seed treatment and compound formulation development and application.

[0003] Ipconazole, chemical formula C 18 H 24 ClN3O is a triazole fungicide and an ergosterol biosynthesis inhibitor. Its mechanism of action mainly involves inhibiting the synthesis of ergosterol in pathogenic fungi at different sites of action, thereby causing cell membrane damage and death. It has a broad fungicidal spectrum, good systemic conductivity, and both protective and curative effects, and requires only a small dosage. It can be widely used in rice, cereals, ornamental plants, and non-crop fields to control various seed diseases.

[0004] Benzothiazolinone (C7H5NOS) is a novel, broad-spectrum fungicide belonging to the benzothiazolinone class. Its mechanism of action primarily involves disrupting the nuclear structure of pathogen cells, causing them to lose their "heart" and die, and interfering with the metabolism of pathogen cells, leading to physiological disorders and ultimately death. It is widely used to control various bacterial and fungal diseases, including cucumber downy mildew, bacterial angular leaf spot, tomato bacterial wilt, tobacco wildfire, pear scab, apple scab, rot, citrus canker, anthracnose, grape black rot, rice bacterial blight, and bakanae disease. This compound exhibits a strong stereochemical mechanism of action, making it difficult for pathogens to develop resistance, and it is very safe for crops, thus holding an important position in the control of both fungal and bacterial diseases.

[0005] Seed-borne diseases pose a significant threat to agricultural production. Rice bakanae disease and peanut root rot, in particular, are characterized by their insidious onset and rapid spread, often leading to missing seedlings and yield reductions of 20%–50%. Current control methods mostly employ single fungicides or binary compound formulations, which often exhibit poor formulation stability, frequently exhibiting issues such as water separation or sedimentation, reduced fluidity, and strong resistance. These not only affect the effectiveness of seed coatings but may also lead to reduced or ineffective efficacy. Therefore, it is difficult to meet the current agricultural demand for the most efficient, safe, and long-lasting disease control. Thus, the rational combination of these three active ingredients, through complementary mechanisms of action, can effectively control rice bakanae disease and peanut root rot. Currently, there are no reports of this ternary combination being used for the control of rice and peanut diseases. Summary of the Invention

[0006] This invention addresses the technical shortcomings of current pesticides for controlling rice bakanae disease and peanut root rot, such as poor synergistic effects in compound formulations, insufficient formulation stability, and high risk of resistance. By screening the compound ratio of active ingredients, optimizing the adjuvant system, and refining the preparation process, this invention provides a ternary compound seed treatment suspension that achieves highly efficient synergistic control of both diseases, while simultaneously improving seed germination rate and crop yield. The specific technical solution is as follows:

[0007] One aspect of this invention relates to a seed treatment agent containing metalaxyl, tebuconazole and thiamethoxam, wherein the active ingredients of the seed treatment agent are metalaxyl, tebuconazole and thiamethoxam, and the mass ratio of the three is 1~3:1~5:1~3.

[0008] In the mass ratios described in this invention, the mass ratio values ​​of metalaxyl-M can be selected from 1, 1.5, 2, 2.5, 3, etc.; the mass ratio values ​​of tebuconazole can be selected from 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc.; the mass ratio values ​​of thiamethoxam can be selected from 1, 1.5, 2, 2.5, 3, etc. (For example, if the mass ratio value of metalaxyl-M is a, the mass ratio value of tebuconazole is b, and the mass ratio value of thiamethoxam is c, then the mass ratio of metalaxyl-M, tebuconazole, and thiamethoxam is a:b:c).

[0009] In one embodiment of the present invention, the mass ratio of metalaxyl, tebuconazole and thiamethoxam in the seed treatment agent of the present invention is preferably 3:5:3, 3:5:2, 3:5:1, 3:4:3, 3:4:2, 3:4:1, 3:3:2, 3:2:1, 1:1:1, 2:5:3, 2:5:1, 2:4:3, 2:1:2, 2:3:2, 1:5:3; more preferably 3:4:3.

[0010] In one embodiment of the present invention, the three active ingredients account for 1% to 85% of the total mass of the seed treatment agent, and the remainder are auxiliary ingredients that are permissible to be added in agricultural production.

[0011] The seed treatment agent of the present invention can be prepared into seed treatment suspension, seed treatment dry powder, seed treatment soluble agent and seed treatment soluble powder, preferably prepared into seed treatment suspension.

[0012] Therefore, in a preferred embodiment of the present invention,

[0013] This invention relates to a seed treatment suspension containing metalaxyl, tebuconazole, and thiamethoxam. The raw material composition comprises the following components and their weight percentages: metalaxyl 1%~3%, tebuconazole 1%~5%, thiamethoxam 1%~3%, dispersant 5%~12%, wetting agent 2%~5%, film-forming agent 3%~8%, thickener 0.2%~5%, antifreeze 2%~6%, preservative 0.1%~0.5%, defoamer 0.3%~1.0%, warning color 3%~12%, with the balance being deionized water.

[0014] The mass ratio of the three compounds, namely metalaxyl, tebuconazole, and thiamethoxam, is as described above, and:

[0015] The dispersant is selected from one or two of sodium lignosulfonate, naphthalene sulfonate formaldehyde condensate, polycarboxylate, sulfate ester, and alkylphenol polyoxyethylene ether formaldehyde condensate sulfate.

[0016] The wetting agent is selected from one or two of sodium dodecyl sulfate, nonylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate, pull-apart powder BX, fatty alcohol polyoxyethylene ether, and block polyether;

[0017] The film-forming agent is selected from one or two of polyvinyl alcohol, polyethylene glycol, chitosan oligosaccharide, sodium carboxymethyl cellulose, gum arabic, and sodium alginate;

[0018] The thickener is selected from one or two of xanthan gum, hydroxypropyl methylcellulose, magnesium aluminum silicate, sodium carboxymethyl cellulose, and attapulgite.

[0019] The antifreeze is selected from one or two of ethylene glycol, glycerol, propylene glycol, urea, and calcium chloride;

[0020] The preservative is selected from one or two of isothiazolinones, sodium benzoate, potassium sorbate, and paraformaldehyde;

[0021] The defoamer is selected from one or two of the following: organosilicon, polyether, fatty acid ester, and dimethyl silicone oil;

[0022] The warning color is selected from one or two of the following: basic rose essence, acid red, magenta, brilliant blue, water-based rose red, and lemon yellow.

[0023] Another aspect of the present invention relates to a method for preparing the seed treatment suspension, wherein the specific preparation method is as follows: Other components besides the film-forming agent and warning color, including metalaxyl, tebuconazole, thiamethoxam, dispersant, wetting agent, thickener, antifreeze, preservative, defoamer, and deionized water, are accurately weighed according to the specified ratio. The mixture is then homogenized and dispersed in a high-speed shear emulsifying disperser for approximately 30 minutes. Zirconium beads at a weight ratio of 1:1.5 are then added, and the mixture is milled for approximately 1.5 hours. The mixture is then filtered and collected. Finally, the film-forming agent and warning color are added to the collected sample in proportion, and the mixture is homogenized and stirred for approximately 30 minutes. After thorough mixing, the final seed treatment suspension sample is obtained.

[0024] Another aspect of this invention relates to the application of the seed treatment agent or seed treatment suspension of this invention in seed coating for the prevention and control of crop diseases. Preferably, the seed treatment agent or seed treatment suspension of this invention is used to coat rice seeds to prevent the occurrence of rice bakanae disease; or, the seed treatment agent or seed treatment suspension of this invention is used to coat peanut seeds to prevent the occurrence of peanut root rot.

[0025] By adopting the above technical solution, the seed treatment suspension of this application can effectively protect rice and peanut seeds from rice bakanae disease and peanut root rot, promote seed germination and growth, and improve seed stress resistance and crop yield. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer and easier to understand, specific indoor activity assays and field efficacy trials will be used to fully demonstrate them below. However, this invention is not limited to the embodiments described below. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0027] I. Indoor bioassay activity determination

[0028] Example 1: Screening of compound ratios of metalaxyl, cymoxanil, and thiamethoxam against rice bakanae disease and determination of co-toxicity coefficients.

[0029] 1. Test conditions

[0030] 1.1 Test Target

[0031] The tested rice bakanae disease was caused by *Gibberella fujikuroi*, a fungus belonging to the Ascomycota. The pathogen was provided by the Plant Pathology Laboratory, Department of Plant Protection, Fujian Agriculture and Forestry University.

[0032] 1.2 Cultivation Conditions

[0033] Before the assay, the mycelium was inoculated on PDA medium plates and pre-cultured at 26°C for 4 days. A 5 mm diameter mycelial block was taken from the edge of the colony for assay.

[0034] 1.3 Instruments and Equipment

[0035] Biochemical incubator, SW-CJ-2F double-sided clean bench, as well as Eppendorf pipettes, oven, punch, petri dishes, etc.

[0036] 2. Experimental Design

[0037] 2.1 Test reagents

[0038] 96% metalaxyl technical grade (Hebei Xingbai Agricultural Technology Co., Ltd.), 96.5% cymoxanil technical grade (Zhejiang Yulong Biotechnology Co., Ltd.), 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.).

[0039] 2.2 Test Treatment

[0040] 2.2.1 Dosage setting

[0041] The test agents metalaxyl, tebuconazole, and thiamethoxam were prepared into a stock solution with acetone, and then diluted with 2% Tween 80 sterile water. Metalaxyl, tebuconazole, and thiamethoxam were then compounded in 15 different ratios, namely 3:5:3, 3:5:2, 3:5:1, 3:4:3, 3:4:2, 3:4:1, 3:3:2, 3:2:1, 1:1:1, 2:5:3, 2:5:1, 2:4:3, 2:1:2, 2:3:2, and 1:5:3. After the reagents were prepared for the tests, 1 ml of each of the designed series of ratios was pipetted into a sterile conical flask containing 44 ml of PDA medium that had been cooled to 40℃~50℃. After thorough mixing, the mixture was poured into three petri dishes to prepare plates with the corresponding concentrations of the drug. The drug-free medium was set as a blank control (sterile water containing 2% Tween 80 was used instead of the reagent).

[0042] 2.2.2 Experimental Repetition

[0043] Each concentration treatment was repeated three times.

[0044] 3. Test Methods

[0045] Refer to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2-2006", mycelial growth rate method.

[0046] Pre-prepared mycelial blocks were inoculated onto PDA agar plates with different drug concentrations and cultured at 26°C for 4 days. Colony diameter was measured using the cross-hatching method, the average colony diameter was calculated, and the EC50 of different drugs on the strains was determined. 50 The co-toxicity coefficient (CTC) of the mixture was calculated using the co-toxicity coefficient calculation method. The synergistic effect of the mixture was determined using the following specific calculation method:

[0047] Using a single agent from the mixture as the standard reagent (usually EC) 50 (The lower one), calculate:

[0048] Single-dose toxicity index = standard agent EC 50 / A single-dose EC 50 ×100

[0049] Actual toxicity index (ATI) = EC of standard single dose 50 EC values / mixtures 50 value × 100

[0050] Theoretical Toxicity Index (TTI) = Toxicity Index of Single Agent A × Proportion of Single Agent A in the Mixture + Toxicity Index of Single Agent B × Proportion of Single Agent B in the Mixture + Toxicity Index of Single Agent C × Proportion of Single Agent C in the Mixture

[0051] Cotoxicity coefficient (CTC) = Measured toxicity index / Theoretical toxicity index × 100

[0052] Co-toxicity coefficient classification: when CTC is greater than 120, the mixture has synergistic effect; when CTC is less than 80, it is antagonistic; and when CTC is between 80 and 120, it has additive effect.

[0053] Table 1. Results of toxicity tests of different ratios of metalaxyl, cymoxanil, and thiamethoxam against rice bakanae disease.

[0054] Table 1 shows the EC50 of tebuconazole and thiamethoxam for controlling rice bakanae disease. 50 The concentrations of the three active ingredients were 0.761 mg / L and 3.856 mg / L, respectively. The CTCs produced by mixing the three active ingredients in the preferred ratio of 1~3:1~5:1~3 were all superior to the CTCs produced by mixing them in pairs, showing a significant synergistic effect. In particular, when the ratio of the three ingredients was 3:4:3, the co-toxicity coefficient was the highest at 168.42, showing the best synergistic effect.

[0055] Example 2: Screening of compound ratios of metalaxyl, cymoxanil, and thiamethoxam against peanut root rot and determination of co-toxicity coefficient.

[0056] 1. Test conditions

[0057] 1.1 Test Target

[0058] The tested pathogen for peanut root rot was mainly the common fungus *Pythium myriotylum*, belonging to the Deuteromycetes, and was provided by the Plant Pathology Laboratory of the Department of Plant Protection, Shandong Agricultural University.

[0059] 1.2 Cultivation Conditions

[0060] Before the assay, the mycelium was inoculated on PDA medium plates and pre-cultured at 28°C for 5 days. A 5 mm diameter mycelial block was taken from the edge of the colony for assay.

[0061] 1.3 Instruments and Equipment

[0062] Biochemical incubator, SW-CJ-2F double-sided clean bench, as well as Eppendorf pipettes, oven, punch, petri dishes, etc.

[0063] 2. Experimental Design

[0064] 2.1 Test reagents

[0065] 96% metalaxyl technical grade (Hebei Xingbai Agricultural Technology Co., Ltd.), 96.5% cymoxanil technical grade (Zhejiang Yulong Biotechnology Co., Ltd.), 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.).

[0066] 2.2 Test Treatment

[0067] 2.2.1 Dosage setting

[0068] The test agents metalaxyl, tebuconazole, and thiamethoxam were prepared into a stock solution with acetone, and then diluted with 2% Tween 80 sterile water. Metalaxyl, tebuconazole, and thiamethoxam were then compounded in 15 different ratios, namely 3:5:3, 3:5:2, 3:5:1, 3:4:3, 3:4:2, 3:4:1, 3:3:2, 3:2:1, 1:1:1, 2:5:3, 2:5:1, 2:4:3, 2:1:2, 2:3:2, and 1:5:3. After the reagents were prepared for the tests, 1 ml of each of the designed series of ratios was pipetted into a sterile conical flask containing 44 ml of PDA medium that had been cooled to 40℃~50℃. After thorough mixing, the mixture was poured into three petri dishes to prepare plates with the corresponding concentrations of the drug. The drug-free medium was set as a blank control (sterile water containing 2% Tween 80 was used instead of the reagent).

[0069] 2.2.2 Experimental Repetition

[0070] Each concentration treatment was repeated three times.

[0071] 3. Test Methods

[0072] Refer to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2-2006", mycelial growth rate method.

[0073] Pre-prepared mycelial blocks were inoculated onto PDA agar plates containing different concentrations of the pesticide and cultured at 28°C for 5 days. Colony diameter was measured using the cross-hatching method, the average colony diameter was calculated, and the EC50 of different pesticides on the strains was determined. 50 The co-toxicity coefficient (CTC) of the mixture was calculated using the co-toxicity coefficient calculation method. The synergistic effect of the mixture was determined using the same calculation method as above.

[0074] Table 2. Results of toxicity tests of different ratios of metalaxyl, cymoxanil, and thiamethoxam against peanut root rot.

[0075] Table 2 shows the results of the tests: metalaxyl, cymoxanil, and thiamethoxam have an EC50 effect on peanut root rot. 50 The concentrations were 0.183 mg / L, 0.548 mg / L, and 3.495 mg / L, respectively. After mixing the three active ingredients in the preferred mass ratio of 1~3:1~5:1~3, the co-toxicity coefficients were compared with those of the three active ingredients in pairs. It was found that the co-toxicity coefficients of the three active ingredients in pairs were all >120, which showed a significant synergistic effect. In particular, when the ratio of the three active ingredients was 3:4:3, the co-toxicity coefficient was the largest at 171.86, showing the best synergistic effect.

[0076] II. Field efficacy trials

[0077] Based on the indoor toxicity tests of metalaxyl, thiamethoxam, and tebuconazole against rice bakanae disease and peanut root rot, the co-toxicity coefficient and synergistic effect were found to be highest when the ratio of the three active ingredients was 3:4:3. Therefore, further screening of the optimal stable formulation and field efficacy under different adjuvant systems was conducted for this ratio. Specific formulation examples are as follows:

[0078] Homemade Reagent Example 1: 3% metalaxyl-M, 4% thiamethoxam, 3% tebuconazole, 3% ammonium polycarboxylate, 2% sodium sulfate, 2.5% nonylphenol EO-PO block polyether, 0.22% xanthan gum, 2% magnesium aluminum silicate, 4% glycerol, 0.2% Kathon, 0.3% silicone defoamer, 5% sodium alginate, 4% Acid Red, with the remainder being deionized water.

[0079] Homemade Reagent Example 2: 3% metalaxyl-M, 4% thiamethoxam, 3% tebuconazole, 5% sodium polycarboxylate, 2% nonylphenol EO-PO block polyether, 0.25% xanthan gum, 2% magnesium aluminum silicate, 4% urea, 0.2% Kathon, 0.3% silicone defoamer, 5% sodium alginate, 4% tartrazine, with the remainder made up with deionized water.

[0080] Homemade Reagent Example 3: 3% metalaxyl-M, 4% thiamethoxam, 3% tebuconazole, 6% sodium polycarboxylate, 2% nonylphenol polyoxyethylene ether, 0.22% xanthan gum, 2% magnesium aluminum silicate, 4% glycerol, 0.2% Kathon, 0.3% silicone defoamer, 5% chitosan oligosaccharide, 2% water-based rose red, 5% acid red, with the remainder being deionized water.

[0081] Homemade Reagent Example 4: 3% metalaxyl-M, 4% thiamethoxam, 3% tebuconazole, 5% sodium lignosulfonate, 2% nonylphenol polyoxyethylene ether, 2.5% nonylphenol EO-PO block polyether, 0.25% xanthan gum, 1.8% magnesium aluminum silicate, 4% glycerol, 0.2% Kathon, 0.3% silicone defoamer, 5% chitosan oligosaccharide, 5% Acid Red, with the remainder being deionized water.

[0082] Homemade Reagent Example 5: 3% metalaxyl-M, 4% thiamethoxam, 3% tebuconazole, 5.5% sodium lignosulfonate, 2.5% sodium dodecylbenzenesulfonate, 2.5% fatty alcohol polyoxyethylene ether, 0.2% xanthan gum, 2% magnesium aluminum silicate, 4% glycerol, 0.2% Kathon, 0.3% silicone defoamer, 5% sodium carboxymethyl cellulose, 2% water-based rose red, 5% acid red, with the remainder being deionized water.

[0083] The preparation methods of Examples 1-5 are as follows: All components except the film-forming agent and warning color, including metalaxyl, tebuconazole, thiamethoxam, dispersant, wetting agent, thickener, antifreeze, preservative, defoamer, and deionized water, are accurately weighed according to the specified ratio. The mixture is then homogenized and dispersed in a high-speed shear emulsifying disperser for approximately 30 minutes. Zirconium beads at a weight ratio of 1:1.5 are then added, and the mixture is milled for approximately 1.5 hours. The mixture is then filtered and collected. Finally, the film-forming agent and warning color are added to the collected sample in proportion, and the mixture is homogenized and stirred for approximately 30 minutes. After thorough mixing, the final seed treatment suspension sample is obtained.

[0084] Table 3. Quality control indicators for seed treatment suspension formulations under different adjuvant systems.

[0085] Example 1: Field efficacy trial of metalaxyl, cymoxanil and thiamethoxam against rice bakanae disease

[0086] 1.1 Test reagents and treatment

[0087] Table 4 Test reagents and treatments

[0088] 1.2 Test Methods

[0089] Rice variety tested: Heliangyou 631

[0090] Experimental site selection: The experimental site was located in Shunchang, Fujian Province. The soil in the experimental field was red soil with medium to high fertility and a pH value of 6.3. The previous crop was rice.

[0091] Experimental Design: The experiment included nine treatments: Examples 1-5, 10% metalaxyl seed treatment suspension, 5% thiamethoxam seed treatment suspension, 41% tebuconazole seed treatment suspension, and a water control (CK). The seed-to-pesticide ratio was as described in Table 4 above. All treatments involved a single seed dressing one day before sowing. For each treatment, 2 kg of rice seeds were weighed and added to a seed dressing machine, followed by water at a machine-to-seed-to-pesticide ratio of 1:50. The mixture was thoroughly mixed with the seeds, dried, and then sown. On April 15, 2024, the treated rice seeds were sown in machine-transplanted plastic trays. Each treatment had 15 trays, with 100 seeds per tray for easy observation of germination rate. After even watering, the trays were placed in the seedbed and covered with non-woven fabric to control the temperature below 35℃. The non-woven fabric was removed after 15 days for hardening off.

[0092] 1.3 Survey Methods

[0093] Emergence rate survey: Sowing was carried out on April 15th, and rice emergence was observed in each treatment area on May 3rd. Using the 70% emergence rate in the water control area as a baseline, the emergence rate and seedling establishment rate of rice in each treatment were statistically analyzed. Next, 30 representative rice plants were selected from each treatment area to investigate plant height, root length, and fresh weight per 100 plants. Finally, the impact of the pesticide on rice emergence was evaluated.

[0094] Control Efficacy Survey: Rice seedlings were transplanted on May 8th. The incidence of bakanae disease was investigated at the initial and peak stages of the disease. 30 hills were surveyed per treatment, and the total number of plants surveyed and the number of diseased plants were recorded. The incidence rate and control efficacy were calculated. The disease grading standards for rice bakanae disease are as follows:

[0095] Grade 0: Disease-free plants with a disease incidence rate of 0%.

[0096] Grade 1: Disease incidence rate is between 1% and 5%. Diseased plants show slight excessive growth, are slightly taller than healthy plants, have thinner stems, and pale green leaves.

[0097] Level 3: Disease incidence rate is between 6% and 15%. Diseased plants are significantly elongated, 10% to 20% taller than healthy plants, with thin and weak stems, some leaves turning yellow, and reduced tillering.

[0098] Level 5: Disease incidence rate is between 16% and 30%. Diseased plants are 20% to 30% taller than healthy plants, with significantly thin and weak stems, yellowing or curled leaves, and most diseased plants produce few or no tillers. Some diseased plants begin to wither.

[0099] Level 7: Disease incidence rate is between 30% and 50%, diseased plants are 30% to 40% taller than healthy plants, stems grow abnormally, and some wither and die.

[0100] Level 9: Disease incidence exceeds 50%. Diseased plants exhibit severely abnormal growth, with almost all of them withering and dying, showing obvious symptoms in the field.

[0101] After statistically recording the diseased plants according to the relevant national field trial standards, the disease index and control effect were calculated, and the significance of the control effect was analyzed using the Duncan's multiple range test (DMRT) method.

[0102] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100

[0103] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0104] Disease index = 100 × ∑(number of diseased plants at each level × relative level value) / (highest disease level × total number of plants surveyed)

[0105] Control efficacy (%) = (Disease index in control area - Disease index in drug-treated area) / Disease index in control area × 100

[0106] Table 5 Effects of different treatments on rice seed germination and emergence

[0107] Table 6. Control effects of different treatments on rice bakanae disease

[0108] Note: Lowercase letters indicate significant differences (P < 0.05), and uppercase letters indicate significant differences (P < 0.01).

[0109] Observations in Tables 5 and 6 show that, for Examples 1-5 with the same active ingredient content but different adjuvant systems, the rice seeds treated with the suspension in Example 3 exhibited superior germination rate and growth compared to other examples and the control. The emergence rate and seedling establishment rate were 95.33% and 92.67%, respectively. Furthermore, the average plant height, underground root length, and fresh weight per 100 plants of the treated rice seeds were significantly better than those of other examples and the control, and the overall growth was uniform and good. In addition, Example 3 showed the best control effect against rice bakanae disease at the early and peak stages of the disease, with control efficiencies of 94.11% and 92.11%, respectively. Therefore, the above analysis demonstrates that the rational combination of these three active ingredients has a good effect of reducing dosage and increasing efficacy. Moreover, no phytotoxicity was observed during the entire experimental investigation.

[0110] Example 2: Field efficacy trials of metalaxyl, cymoxanil, and thiamethoxam against peanut root rot.

[0111] 2.1 Test reagents and treatment

[0112] Same as "Table 4 Test reagents and treatment".

[0113] 2.2 Test Methods

[0114] Peanut variety tested: Huayu 25.

[0115] Experimental site: Weihai, Shandong Province. The soil in the experimental field is sandy loam with moderate fertility and a pH of 6.1. The previous crop was corn.

[0116] Experimental Design: The experiment included nine treatments: Examples 1-5, 10% metalaxyl seed treatment suspension, 5% thiamethoxam seed treatment suspension, 41% tebuconazole seed treatment suspension, and a water control (CK). The seed treatment methods listed in Table 4 were used, and all seeds were treated once before sowing. For each treatment, 10 kg of peanut seeds were weighed and added to a seed mixer, followed by water at a ratio of 1:100 (machine-to-seed ratio). The mixture was thoroughly mixed with the seeds, dried, and then sown. Sowing took place on May 10, 2024. Each of the nine treatments was replicated three times, resulting in 27 plots. Each plot had three rows and an area of ​​30 m². 2 Each neighborhood is arranged using a randomized block grouping.

[0117] 2.3 Survey Methods

[0118] Emergence rate survey: Sowing was completed on May 10. After sowing, the emergence rate of each treatment was observed and recorded regularly; on May 25, the peanut emergence rate was counted. Five points were randomly selected from each plot, and 25 holes were investigated at each point to evaluate the effect of the pesticide on the peanut emergence rate and observe the peanut growth.

[0119] Control effect survey: During the peanut seedling stage, a 5-point sampling method with a "Z" pattern was used to investigate 30 plants in each plot to investigate the occurrence of peanut root rot in the field, count the number of diseased plants, and calculate the incidence rate and control effect.

[0120] The classification standards for peanut root rot disease are as follows:

[0121] Level 0: No diseases or pests;

[0122] Grade 1: The roots are slightly discolored, with the discolored roots accounting for less than 10% of the total root system, and the plant is not wilting;

[0123] Level 3: The roots are noticeably brown, accounting for 10.1% to 30% of the total root system, and the plant begins to wilt;

[0124] Level 5: Discolored roots account for 30.1% to 50% of the total root system, and the plant is noticeably wilted;

[0125] Level 7: Discolored roots account for 50.1% to 80% of the total root system, and the plant wilts;

[0126] Level 9: The entire plant has died.

[0127] Yield survey: After harvesting peanuts from each plot, all mature pods were picked, brought indoors to dry, and used for seed testing and yield measurement.

[0128] After statistically recording the diseased plants according to the relevant national field trial standards, the disease index and control effect were calculated, and the significance of the control effect was analyzed using the Duncan's multiple range test (DMRT) method.

[0129] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100

[0130] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0131] Disease index = 100 × ∑(number of diseased plants at each level × relative level value) / (highest disease level × total number of plants surveyed)

[0132] Control efficacy (%) = (Disease index in control area - Disease index in drug-treated area) / Disease index in control area × 100

[0133] When the peanuts are harvested, the pod yield of each plot is measured, the actual yield per hectare is calculated, and the yield increase rate is calculated.

[0134] Yield increase rate (%) = (Pod yield in treatment area - Pod yield in control area) / Pod yield in control area × 100

[0135] Table 7. Control efficacy of different treatments on peanut field emergence rate and peanut root rot.

[0136] Table 8 Effects of different treatments on peanut yield

[0137] Note: Lowercase letters indicate significant differences (P < 0.05), and uppercase letters indicate significant differences (P < 0.01).

[0138] Observations in Tables 7 and 8 show that, among Examples 1-5 and the other three control agents with the same active ingredient content but different adjuvant systems, the peanut seeds treated in Example 3 showed a significantly higher germination rate and control efficiency against peanut root rot 15 days after sowing (95.20% and 93.21%, respectively), both significantly better than the other examples and control agents. Furthermore, the treatment significantly reduced the incidence of diseased plants. In addition, yield measurements after peanut harvest showed that the peanut seeds treated in Example 3 had a yield increase of 41.90%, also significantly better than other agents, and no phytotoxicity occurred during use, indicating safe application.

[0139] This invention's seed treatment suspension, through a rational formulation of metalaxyl, tebuconazole, and thiamethoxam, and after indoor toxicity and optimal adjuvant system screening and field efficacy trials, has demonstrated that "Example 3," where the ratio of metalaxyl:tebuconazole:thiamethoxam is 3:4:3, exhibits a significant synergistic effect among the three agents, effectively controlling rice bakanae disease and peanut root rot with excellent control efficacy. Simultaneously, this seed treatment suspension demonstrates high safety, has no adverse effects on crop growth, helps improve crop yield and quality, reduces the use of chemical pesticides, lowers the risk of pathogen resistance development, and possesses good economic and ecological benefits, showing broad application prospects in agricultural production.

Claims

1. A seed treatment agent containing metalaxyl, tebuconazole and thiamethoxam, wherein the active ingredients of the seed treatment agent are metalaxyl, tebuconazole and thiamethoxam, and the mass ratio of the three is 1~3:1~5:1~3.

2. The seed treatment agent according to claim 1, characterized in that: The three active ingredients account for 1-85% of the total mass of the treatment agent, and the remainder are auxiliary ingredients that are permitted to be added in agricultural production.

3. The seed treatment agent according to claim 1, characterized in that: The seed treatment agent can be prepared as a seed treatment suspension, a seed treatment dry powder, a seed treatment soluble solution, and a seed treatment soluble powder.

4. The seed treatment agent according to claim 3, characterized in that: The seed treatment agent is preferably prepared as a seed treatment suspension.

5. A seed treatment suspension containing metalaxyl, tebuconazole, and thiamethoxam, characterized in that, It contains the following ingredients and their weight percentages: metalaxyl 1%~3%, tebuconazole 1%~5%, thiamethoxam 1%~3%, dispersant 5%~12%, wetting agent 2%~5%, film-forming agent 3%~8%, thickener 0.15%~0.3%, antifreeze 2%~6%, preservative 0.1%~0.5%, defoamer 0.3%~1.0%, warning color 3%~12%, with the balance being deionized water.

6. The seed treatment suspension according to claim 5, characterized in that, The dispersant is selected from one or two of sodium lignosulfonate, naphthalene sulfonate formaldehyde condensate, polycarboxylate, and alkylphenol polyoxyethylene ether formaldehyde condensate sulfate. The wetting agent is selected from one or two of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, pull-out powder BX, fatty alcohol polyoxyethylene ether, and block polyether; The film-forming agent is selected from one or two of polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, gum arabic, and sodium alginate; The thickener is selected from one or two of xanthan gum, hydroxypropyl methylcellulose, magnesium aluminum silicate, sodium carboxymethyl cellulose, and attapulgite. The antifreeze is selected from one or two of ethylene glycol, glycerol, propylene glycol, urea, and calcium chloride; The preservative is selected from one or two of isothiazolinones, sodium benzoate, potassium sorbate, and paraformaldehyde; The defoamer is selected from one or two of the following: organosilicon, polyether, fatty acid ester, and dimethyl silicone oil; The warning color is selected from one or two of the following: basic rose essence, acid red, magenta, brilliant blue, water-based rose red, and lemon yellow.

7. A method for preparing the seed treatment suspension according to claim 5, characterized in that, The process includes the following steps: Accurately weigh all ingredients except the film-forming agent and warning color, including metalaxyl, tebuconazole, thiamethoxam, dispersant, wetting agent, thickener, antifreeze, preservative, defoamer, and deionized water, according to the specified proportions. Then, homogenize and disperse these ingredients in a high-speed shear emulsifying disperser for approximately 30 minutes. Finally, add an ingredient with a weight ratio of 1: Zirconium beads of 1.5 mm were sand-milled for about 1.5 hours, then filtered and collected. Finally, film-forming agent and warning color were added to the collected sample in proportion and homogenized and stirred for about 30 minutes. After being mixed evenly, the sample was discharged to obtain the final seed treatment suspension sample.

8. The application of the seed treatment agent according to any one of claims 1-4 or the seed treatment suspension according to any one of claims 5-6 for seed coating to prevent crop diseases.

9. The application according to claim 8, characterized in that, It is preferred for coating rice seeds to prevent the occurrence of rice bakanae disease.

10. The application according to claim 8, characterized in that, It is preferred for coating peanut seeds to prevent peanut root rot.

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