Seed treatment agent containing metalaxyl-M, benziothiazolinone and pydiflumetofen and application thereof

Abstract

The invention discloses a seed treatment agent containing metalaxyl-M (A), benziothiazolinone (B) and pydiflumetofen (C) and application of the seed treatment agent. The mass ratio of the metalaxyl-M to the benziothiazolinone to the pydiflumetofen is (1-10): (1-5): (1-10). Secondly, the three effective components are compounded and prepared into the seed treatment suspending agent, and the seed treatment suspending agent can effectively prevent and treat rice bakanae disease, rice seedling rot, peanut damping-off and corn stalk rot. Through synergistic interaction of the three components, the bactericidal spectrum is effectively expanded, and the emergence rate of rice, peanut and corn seeds and the stress resistance of crops can be greatly improved, so that the yield is improved.

Description

Technical Field

[0001] This invention belongs to the field of agricultural plant protection technology, specifically relating to a seed treatment agent containing metalaxyl, thiamethoxam and fluopyram, and its application in the prevention and control of rice seedling blight, rice seedling rot, peanut damping-off and corn stem rot. Background Technology

[0002] Metalaxyl-m, chemical formula: C 15 H 21 NO4, the R-isomer of metalaxyl, is a benzamide fungicide isolated and purified from metalaxyl. It is characterized by high efficiency, low toxicity, and broad spectrum. Its main mechanism of action is to effectively inhibit fungal protein synthesis, disrupt cell membrane structure and the affinity of target sites, and exhibits strong bidirectional systemic absorption in crops. After application, it rapidly inhibits the reproduction and spread of pathogens within plant tissues and has a long-lasting effect. In agricultural production, it is commonly used through foliar spraying and seed treatment to control common diseases such as downy mildew, early and late blight, pyogenic, bakanae disease, damping-off, seedling rot, root rot, seedling blight, anthracnose, and wilt in cucumbers, tomatoes, peppers, tobacco, rice, cotton, corn, potatoes, grapes, and citrus. Meanwhile, due to its high efficiency and environmental friendliness, metalaxyl has become a mainstream agent for controlling oomycete diseases, especially suitable for seed treatment and the development and use of compound formulations.

[0003] Benzisothiazolinone (C7H5NOS) is a novel, broad-spectrum fungicide belonging to the benzothiazolinone class. It is primarily 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. Its fungicidal mechanism 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. This compound exhibits a strong stereochemical mode 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.

[0004] Pydiflumetofen, chemical formula: C 16 H 16Cl3F2N3O2, belonging to the SDHI class of fungicides, is a fluopyram-methyl fungicide. As a respiratory inhibitor of pathogens, it suppresses mitochondrial function by interfering with the tricarboxylic acid cycle in respiratory electron transport complex II, preventing energy production, inhibiting pathogen growth, and ultimately leading to pathogen death. In addition, fluopyram-methyl fungicides possess good broad-spectrum, systemic, and highly effective fungicidal properties, and can be used to control diseases caused by various pathogens such as Alternaria and Fusarium. It is currently widely used on crops such as wheat, rapeseed, peanuts, strawberries, grapes, and tomatoes in my country.

[0005] Rice, as a globally important food crop, faces serious diseases during its seedling stage, such as bakanae disease and rice seedling rot. Bakanae disease causes excessive vegetative growth and weak plants, which can severely impact yield and quality. Rice seedling rot causes mass seedling death, increasing planting costs and delaying planting seasons. Peanut damping-off is a common disease in peanut cultivation, causing root and stem rot in peanut seedlings, leading to missing seedlings and significantly impacting yield. Corn stem rot (also known as bacterial wilt) is a significant soil-borne disease affecting corn production in my country, occurring in all corn-growing areas, but particularly severe in the Huang-Huai-Hai summer corn region (Henan, Anhui, Shandong, etc.) and the Northeast spring corn region. Infected areas typically experience yield reductions of 20%–30%, with severe cases resulting in reductions of over 50% or even total crop failure.

[0006] Currently, the long-term use of single-agent treatments for the above-mentioned diseases has led to strong drug resistance in pathogens, resulting in a gradual decline in control efficacy. Simultaneously, some agents suffer from high toxicity and short-lasting effects, posing potential harm not only to the environment and non-target organisms but also failing to meet the agricultural demand for efficient, safe, and long-lasting disease control. Therefore, developing a safe, efficient, and synergistic seed treatment agent to control rice bakanae disease, rice seedling rot, peanut damping-off, and corn stem rot is of great significance. Furthermore, a search of current patents and literature has not revealed any reports of compound seed treatment agents containing metalaxyl, thiamethoxam, and fluopyram. Summary of the Invention

[0007] The purpose of this invention is to provide a seed treatment agent containing metalaxyl, thiamethoxam, and fluopyram and its application. The preferred formulation of this seed treatment agent is a seed treatment suspension, used for coating and mixing rice, peanut, and corn seeds. Indoor toxicity and field efficacy tests have fully demonstrated that the use of this composition can effectively prevent and control rice bakanae disease, rice seedling rot, peanut damping-off, and corn stem rot, while improving the seeds' resistance to adverse external reactions, promoting seed germination, strengthening roots and seedlings, and ultimately achieving increased yield and income.

[0008] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0009] A seed treatment agent containing metalaxyl, thiamethoxam and fluopyram, comprising active ingredients and auxiliary ingredients, wherein the active ingredients are metalaxyl, thiamethoxam and fluopyram, and the mass ratio of the three is 1-10:1-5:1-10.

[0010] As a preferred embodiment of the present invention, the mass ratio of metalaxyl, thiamethoxam and fluopyram is preferably 1-8:1-3:1-5.

[0011] In the seed treatment agent of the present invention, the auxiliary components include one or more of the following: dispersant, wetting agent, penetrant, antifreeze, preservative, thickener, defoamer, film-forming agent, colorant, pH adjuster, and deionized water.

[0012] As a preferred embodiment of the present invention, the seed treatment agent formulation is preferably a seed treatment suspension.

[0013] In the seed treatment agent of the present invention, the seed treatment agent formulation includes: 1% to 30% active ingredient, 2% to 5% dispersant, 2% to 5% wetting agent, 0% to 3% penetrant, 1% to 5% antifreeze agent, 0.1% to 0.3% preservative, 0.1% to 4% thickener, 0.3% to 1% defoamer, 3% to 5% film-forming agent, 3% to 20% colorant, 0% to 3% pH adjuster, and deionized water to make up to 100%.

[0014] This invention also proposes the application of a seed treatment agent containing metalaxyl, thiamethoxam, and fluopyram, which is mainly used for seed coating and mixing of rice, peanut, and corn seeds before seedling raising or sowing to prevent the occurrence and infection of rice bakanae disease, rice seedling rot, peanut damping-off, and corn stem base rot during seed germination. Secondly, it can enhance the stress resistance of seeds, thereby effectively improving the seed emergence rate and achieving increased yield and income.

[0015] Therefore, another aspect of the present invention relates to the use of the seed treatment agent for the prevention and control of crop diseases, wherein the seed treatment agent is used to coat and mix crop seeds before seedling cultivation or sowing.

[0016] According to the uses described in this invention, the crops include rice, peanuts, and corn.

[0017] According to the uses described in this invention, the crop diseases include rice bakanae disease, rice seedling rot, peanut damping-off, and maize stem base rot.

[0018] Another aspect of the present invention relates to the use of the seed treatment agent for improving crop traits, wherein the seed treatment agent is used to coat and mix crop seeds before seedling raising or sowing.

[0019] According to the intended use described in this invention, wherein:

[0020] The crop is rice, and the improved crop traits include one or more of the following: increased emergence rate, increased seedling establishment rate, increased average plant height, increased average underground root length, increased average number of roots, and increased total fresh weight; or, the crop is peanut, and the improved crop traits include one or more of the following: increased emergence rate and increased pod yield per acre; or, the crop is corn, and the improved crop traits include one or more of the following: increased plant height, increased emergence rate, and increased yield per acre.

[0021] Compared with existing technologies, the advantages of this invention are as follows: This ternary compound seed treatment agent, through the triple advantages of multi-target synergy (bacteria + fungi), resistance management (triple mechanism of action), and physiological regulation (root growth promotion + stress resistance), solves the core pain points of existing seed coating agents in the prevention and control of rice seedling blight, rice seedling rot, peanut damping-off, and maize stem rot, such as single efficacy, aggravated resistance, and limited function. It also extends the duration of effect and can cover the critical risk period of the entire seedling stage of rice, peanut, and maize when these diseases are prone to occur, thus protecting the successful germination and vigorous growth of seeds. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer and easier to understand, the technical solutions involved in this invention will be described in detail below with reference to specific indoor bioassay and field efficacy test examples. However, this invention is not limited to the following examples. 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.

[0023] I. Indoor bioassay activity determination

[0024] Example 1: Screening of the compound ratio of metalaxyl, thiamethoxam and fluopyram against rice bakanae disease and determination of co-toxicity coefficient.

[0025] 1. Test conditions

[0026] 1.1 Test Target

[0027] 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.

[0028] 1.2 Cultivation Conditions

[0029] 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.

[0030] 1.3 Instruments and Equipment

[0031] Biochemical incubator, SW-CJ-2F double-sided clean bench, as well as Eppendorf pipettes, oven, punch, petri dishes, etc.

[0032] 2. Experimental Design

[0033] 2.1 Test reagents

[0034] 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 96% metalaxyl technical grade (Hebei Xingbai Agricultural Technology Co., Ltd.), and 98% fluopyram technical grade (Syngenta Nantong Crop Protection Co., Ltd.).

[0035] 2.2 Test Treatment

[0036] 2.2.1 Dosage setting

[0037] The test agents metalaxyl, thiamethoxam, and fluopyram were prepared into stock solutions using methanol, and then diluted with 2% Tween 80 sterile water. Metalaxyl-thiamethoxam·thiamethoxam·fluopyram were then compounded in 15 ratios: 8:3:5, 6:3:5, 4:3:5, 2:3:5, 1:3:5, 1:1:1, 1:2:1, 1:1:3, 2:1:5, 4:1:5, 6:1:3, 8:1:5, 2:3:2, 6:3:2, and 8:3:1. After preliminary tests on each agent, the designed series of ratios were added to PDA medium to prepare drug-containing plates. A blank control (containing 2% Tween 80 sterile water instead of water) was set up.

[0038] 2.2.2 Experimental Repetition

[0039] Each concentration treatment was repeated three times.

[0040] 3. Test Methods

[0041] Refer to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2006", mycelial growth rate method.

[0042] 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. 50The 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:

[0043] Using a single agent from the mixture as the standard reagent (usually EC) 50 For the lower one, perform the calculation:

[0044] Single-dose toxicity index = EC of standard drug 50 / A single-dose EC 50 ×100

[0045] Actual toxicity index (ATI) = EC5 of standard single dose 50 EC values / mixtures 50 value × 100

[0046] 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

[0047] Cotoxicity coefficient (CTC) = Measured toxicity index / Theoretical toxicity index × 100

[0048] 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.

[0049] Table 1. Results of toxicity tests of different ratios of metalaxyl, thiamethoxam, and fluopyram against rice bakanae disease.

[0050]

[0051]

[0052] Table 1 shows the test results: Metalaxyl does not inhibit the mycelial growth of the rice bakanae disease pathogen, while thiamethoxam and fluopyram control the EC50 of rice bakanae disease. 50 The concentrations of CTCs were 14.632 ug / mL and 0.027 ug / mL, respectively. The CTCs produced by mixing the three active ingredients in an optimal ratio of 1–8:1–3:1–5 were superior to those produced by mixing them in pairs (80–120, additive effect), demonstrating a significant synergistic effect. In particular, when the ratio of the three ingredients was 6:3:5, the co-toxicity coefficient was the highest at 157.326, exhibiting the best synergistic effect. Example 2: Screening of the compound ratio of metalaxyl-M, thiamethoxam, and fluopyram against rice seedling blight and determination of co-toxicity coefficient.

[0053] 1. Test conditions

[0054] 1.1 Test Target

[0055] The tested rice seedling rot disease was caused by the common fungus *Pythium oryzae et Tokun*, which was collected and isolated from Nanchang County, Jiangxi Province, and stored at room temperature.

[0056] 1.2 Cultivation Conditions

[0057] Before the assay, the mycelium was inoculated on PDA medium plates and pre-cultured at 26°C for 3 days. A 5 mm diameter mycelial block was taken from the edge of the colony for assay.

[0058] 1.3 Instruments and Equipment

[0059] Biochemical incubator, SW-CJ-2F double-sided clean bench, as well as Eppendorf pipettes, oven, punch, petri dishes, etc.

[0060] 2. Experimental Design

[0061] 2.1 Test reagents

[0062] 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 96% metalaxyl technical grade (Hebei Xingbai Agricultural Technology Co., Ltd.), and 98% fluopyram technical grade (Syngenta Nantong Crop Protection Co., Ltd.).

[0063] 2.2 Test Treatment

[0064] 2.2.1 Dosage setting

[0065] The test agents metalaxyl, thiamethoxam, and fluopyram were prepared into stock solutions using methanol, and then diluted with 2% Tween 80 sterile water. Metalaxyl-thiamethoxam·thiamethoxam·fluopyram were then compounded in 15 ratios: 8:3:5, 6:3:5, 4:3:5, 2:3:5, 1:3:5, 1:1:1, 1:2:1, 1:1:3, 2:1:5, 4:1:5, 6:1:3, 8:1:5, 2:3:2, 6:3:2, and 8:3:1. After preliminary tests on each agent, the designed series of ratios were added to PDA medium to prepare drug-containing plates. A blank control (containing 2% Tween 80 sterile water instead of water) was set up.

[0066] 2.2.2 Experimental Repetition

[0067] Each concentration treatment was repeated three times.

[0068] 3. Test Methods

[0069] Refer to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2006", mycelial growth rate method.

[0070] Pre-prepared mycelial blocks were inoculated onto PDA agar plates containing different concentrations of the drug and cultured at 26°C for 3 days. Colony diameters were measured using the cross-sectional method, and the average colony diameter was calculated. The EC50 of different drugs on the strains was also determined. 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.

[0071] Table 2. Results of toxicity tests of different ratios of metalaxyl, thiamethoxam, and fluopyram against rice seedling blight.

[0072]

[0073]

[0074] Table 2 shows the results of the tests: metalaxyl, thiamethoxam, and fluopyram have an effect on the EC50 of rice seedling blight. 50 The concentrations were 0.105 ug / mL, 4.684 ug / mL, and 97.523 ug / mL, respectively. When the effective components were mixed in the preferred ratio of 1-8:1-3:1-5, the co-toxicity coefficients (80-120, additive effect) of the three effective components were compared with those of the three effective components in pairs. It was found that the co-toxicity coefficients of the three effective components were all >120, which showed a significant synergistic effect. In particular, when the ratio of the three effective components was 6:3:5, the co-toxicity coefficient was the largest at 165.333, which showed the best synergistic effect.

[0075] Example 3: Screening of the compound ratio of metalaxyl, thiamethoxam and fluopyram against peanut damping-off and determination of co-toxicity coefficient.

[0076] 1. Test conditions

[0077] 1.1 Test Target

[0078] The pathogen of peanut damping-off was *Rhizoctonia solani* kühn, a member of the Deuteromycetes, and was provided by the Plant Protection and Pathology Laboratory of Henan Agricultural University.

[0079] 1.2 Cultivation Conditions

[0080] Before the assay, the mycelium was inoculated on PDA medium plates and pre-cultured at 25°C for 5 days. A 5 mm diameter mycelial block was taken from the edge of the colony for assay.

[0081] 1.3 Instruments and Equipment

[0082] Biochemical incubator, SW-CJ-2F double-sided clean bench, as well as Eppendorf pipettes, oven, punch, petri dishes, etc.

[0083] 2. Experimental Design

[0084] 2.1 Test reagents

[0085] 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 96% metalaxyl technical grade (Hebei Xingbai Agricultural Technology Co., Ltd.), and 98% fluopyram technical grade (Syngenta Nantong Crop Protection Co., Ltd.).

[0086] 2.2 Test Treatment

[0087] 2.2.1 Dosage setting

[0088] The test agents metalaxyl, thiamethoxam, and fluopyram were prepared into stock solutions using methanol, and then diluted with 2% Tween 80 sterile water. Metalaxyl-thiamethoxam·thiamethoxam·fluopyram were then compounded in 15 ratios: 8:3:5, 6:3:5, 4:3:5, 2:3:5, 1:3:5, 1:1:1, 1:2:1, 1:1:3, 2:1:5, 4:1:5, 6:1:3, 8:1:5, 2:3:2, 6:3:2, and 8:3:1. After preliminary tests on each agent, the designed series of ratios were added to PDA medium to prepare drug-containing plates. A blank control (containing 2% Tween 80 sterile water instead of water) was set up.

[0089] 2.2.2 Experimental Repetition

[0090] Each concentration treatment was repeated three times.

[0091] 3. Test Methods

[0092] Refer to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2006", mycelial growth rate method.

[0093] Pre-prepared mycelial blocks were inoculated onto PDA agar plates containing different concentrations of the drug and cultured at 25°C for 5 days. Colony diameters were measured using the cross-sectional method, and the average colony diameter was calculated. The EC50 of different drugs on the strains was also determined. 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.

[0094] Table 3. Toxicity test results of different ratios of metalaxyl, thiamethoxam, and fluopyram against peanut damping-off.

[0095]

[0096] Table 3 shows the test results: Metalaxyl does not inhibit the mycelial growth of peanut damping-off pathogen, while thiamethoxam and fluopyram control the EC50 of peanut damping-off. 50The concentrations were 7.592 ug / mL and 0.315 ug / mL, respectively. A comparison of the co-toxicity coefficients (80–120, additive effect) of the three active ingredients mixed in the optimal active ingredient mass ratio of 1–8:1–3:1–5 with those of the three active ingredients combined in pairs revealed that the co-toxicity coefficients of all three active ingredients were >120, indicating a significant synergistic effect. The co-toxicity coefficient was highest at 151.244 when the ratio of the three active ingredients was 6:3:5, demonstrating the best synergistic effect.

[0097] Example 4: Screening of the compound ratio of metalaxyl, thiamethoxam and fluopyram against maize stalk rot and determination of co-toxicity coefficient.

[0098] 1. Test conditions

[0099] 1.1 Test Target

[0100] The tested pathogen for maize stalk base rot was Pythium spp., provided by the Plant Protection and Pathology Laboratory of Henan Agricultural University.

[0101] 1.2 Cultivation Conditions

[0102] Before the assay, the mycelium was inoculated on PDA medium plates and pre-cultured at 25°C for 5 days. A 5 mm diameter mycelial block was taken from the edge of the colony for assay.

[0103] 1.3 Instruments and Equipment

[0104] Biochemical incubator, SW-CJ-2F double-sided clean bench, as well as Eppendorf pipettes, oven, punch, petri dishes, etc.

[0105] 2. Experimental Design

[0106] 2.1 Test reagents

[0107] 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 96% metalaxyl technical grade (Hebei Xingbai Agricultural Technology Co., Ltd.), and 98% fluopyram technical grade (Syngenta Nantong Crop Protection Co., Ltd.).

[0108] 2.2 Test Treatment

[0109] 2.2.1 Dosage setting

[0110] The test agents metalaxyl, thiamethoxam, and fluopyram were prepared into stock solutions using DMF, and then diluted with 2% Tween 80 sterile water. Metalaxyl-thiamethoxam·thiamethoxam·fluopyram were then compounded in 15 ratios: 8:3:5, 6:3:5, 4:3:5, 2:3:5, 1:3:5, 1:1:1, 1:2:1, 1:1:3, 2:1:5, 4:1:5, 6:1:3, 8:1:5, 2:3:2, 6:3:2, and 8:3:1. After preliminary testing of each agent, the designed series of ratios were added to PDA medium to prepare drug-containing plates. A blank control (containing 2% Tween 80 sterile water instead of water) was set up.

[0111] 2.2.2 Experimental Repetition

[0112] Each concentration treatment was repeated three times.

[0113] 3. Test Methods

[0114] Refer to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2006", mycelial growth rate method.

[0115] Pre-prepared mycelial blocks were inoculated onto PDA agar plates containing different concentrations of the drug and cultured at 25°C for 5 days. Colony diameters were measured using the cross-sectional method, and the average colony diameter was calculated. The EC50 of different drugs on the strains was also determined. 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.

[0116] Table 4. Toxicity test results of different ratios of metalaxyl, thiamethoxam, and fluopyram against maize stalk rot.

[0117]

[0118] Table 4 shows the EC50 values ​​of metalaxyl, thiamethoxam, and fluopyram for controlling corn stalk rot. 50 The concentrations were 5.613 ug / mL, 12.582 ug / mL, and 0.479 ug / mL, respectively. The CTC values ​​obtained after mixing the active ingredients in optimal ratios of 1–8:1–3:1–5 were superior to the co-toxicity coefficients (80–120, additive effect) of pairwise combinations of active ingredients, with all co-toxicity coefficients >120, demonstrating a significant synergistic effect. Especially when the ratio of the three active ingredients was 6:3:5, the co-toxicity coefficient was the highest at 146.427, exhibiting the best synergistic effect.

[0119] II. Field efficacy trials

[0120] The indoor toxicity tests of metalaxyl, thiamethoxam, and fluopyram against rice bakanae disease, rice seedling blight, peanut damping-off, and corn stem rot show that although metalaxyl is not effective in controlling rice bakanae disease and peanut damping-off, a reasonable combination with thiamethoxam and fluopyram can achieve a certain synergistic effect. Therefore, through indoor toxicity tests on these four crop diseases, the optimal ratio of the three active ingredients was determined to be 6:3:5, i.e., metalaxyl 3%, thiamethoxam 1.5%, and fluopyram 2.5%. A seed treatment suspension will be prepared according to this ratio for subsequent field efficacy trials to fully demonstrate the control effect of the compound composition.

[0121] Homemade medicine example 1:

[0122] (3+1.5+2.5)% Metalaxyl·Thiamethoxam·Fluoxam Hydroxylamine, Seed Treatment Suspension Concentrate

[0123] Homemade Reagent Example 2: 5% Thiamethoxam, Seed Treatment Suspension

[0124]

[0125] Preparation method of seed treatment suspension: The active ingredients, auxiliary ingredients excluding film-forming agents and colorants, and deionized water are accurately weighed according to the specified ratio. Then, the mixture is homogenized and dispersed using a high-speed shear emulsifying disperser. After 30 minutes, zirconium beads at a weight ratio of 1:1.3 are added and the mixture is milled for 1.5 hours. After sampling and testing, if the particle size is ≤5μm, the mixture is filtered to obtain a white slurry. Finally, film-forming agents and colorants are added according to the formula ratio and homogenized for 30 minutes. After thorough mixing, the desired seed treatment suspension is obtained. Example 1: Field efficacy test of metalaxyl, thiamethoxam, and fluopyram against rice bakanae disease 1.1 Test agents and treatments

[0126] Table 5 Test reagents and treatments

[0127]

[0128]

[0129] 1.2 Test Methods

[0130] Rice variety tested: Fudao 41

[0131] Experimental site selection: The experimental site was located in Jianning, Fujian Province. The soil in the experimental field was brown sandy loam with medium to high fertility and a pH value of 6.3. The previous crop was rice.

[0132] Experimental Design: The experiment included five treatments: 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension, 200 g / L fluoxadiazon seed treatment suspension, 5% thiamethoxam SC, 10% metalaxyl-mancozeb seed treatment suspension, and a water control (CK). The seed treatment methods listed in Table 4 were used, and all treatments were performed once 1 day before sowing. For each treatment, 2 kg of rice seeds were weighed and added to a seed treatment machine, followed by water at a machine-to-seed ratio of 1:50. The mixture was thoroughly mixed with the seeds, dried, and then sown. On April 12, 2023, 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.

[0133] 1.3 Survey Methods

[0134] Emergence rate survey: Sowing was carried out on April 12th, and rice emergence was observed in each treatment area on April 28th. 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, total number of roots, and total fresh weight. Finally, the impact of the pesticide on rice emergence was evaluated.

[0135] Control Efficacy Survey: Rice seedlings were transplanted on May 3rd. 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:

[0136] Grade 0: Disease-free plants, with a disease incidence rate of 0%.

[0137] 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.

[0138] Grade 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.

[0139] 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.

[0140] Level 9: Disease incidence exceeds 50%. Diseased plants exhibit severely abnormal growth, almost all of them wither and die, and obvious symptoms are observed in the field.

[0141] 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.

[0142] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100

[0143] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0144] Disease index = 100 × ∑(number of diseased plants at each level × relative level value) / (highest disease level × total number of plants surveyed)

[0145] Control efficacy (%) = (Disease index in control area - Disease index in pesticide-treated area) / Disease index in control area × 100 Table 6 Effects of different treatments on rice seed germination and emergence

[0146]

[0147] Note: Lowercase letters indicate significant differences (P < 0.05).

[0148] Table 7. Control effects of different treatments on rice bakanae disease.

[0149]

[0150]

[0151] Note: ① Lowercase letters indicate significant differences (P < 0.05), and uppercase letters indicate significant differences (P < 0.01).

[0152] ② The actual field control efficacy of 10% metalaxyl seed treatment suspension for controlling peanut seedling blight, combined with indoor toxicity testing, was not significantly different from the control (CK) and can be disregarded.

[0153] Observations in Tables 6 and 7 show that the 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension significantly promoted the germination and growth of rice seeds. Compared with the control agent and the water control, the rice seeds treated with the 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension had a seedling emergence rate of 97.95% and a seedling establishment rate of 96.49%, both superior to the control group. Furthermore, the treated rice seeds showed significantly better growth in later stages, with superior plant height, underground root length, root number, and fresh weight compared to the control group, and exhibited uniform and healthy growth. In addition, this composition showed the best control effect against rice bakanae disease at the early and peak stages of the disease, with control efficiencies of 90.79% and 88.61%, respectively. This demonstrates that the rational combination of these three compounds results in a good dosage-reduction and synergistic effect. Moreover, no phytotoxicity was observed during the entire efficacy investigation, therefore farmers can use it with confidence.

[0154] Example 2: Field efficacy trials of metalaxyl, thiamethoxam, and fluopyram against rice seedling blight.

[0155] 2.1 Test reagents and treatment

[0156] Same as "Table 4 Test Reagents and Treatments".

[0157] 2.2 Test Methods

[0158] Rice variety tested: Jinggang soft sticky rice

[0159] Experimental site: Ji'an, Jiangxi Province. The experimental site is a rice-continuous cropping field where rice seedling rot disease occurs year-round. Mechanized seedling trays were used for seedling raising. The seedling soil was the same as that used in local agricultural production areas. The planting methods, cultivation, and water and fertilizer management conditions were also the same.

[0160] Experimental Design: The experiment included five treatments: 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension, 200 g / L fluoxadiazon seed treatment suspension, 5% thiamethoxam SC, 10% metalaxyl-mancozeb seed treatment suspension, and a water control (CK). The seed treatment methods listed in Table 4 were used, and all treatments were applied once 1 day before sowing. For each treatment, 4 kg of rice seeds were weighed and added to a seed treatment machine, followed by water at a machine-to-seed ratio of 1:50. The mixture was thoroughly mixed with the seeds, dried, and then sown. On March 10, 2024, the treated rice seeds were sown in machine-transplanted plastic trays. Each treatment had 15 trays, with three replicates. Each tray contained 100 seeds 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℃. After 15 days, the non-woven fabric was removed for hardening off.

[0161] 2.3 Survey Methods

[0162] Emergence rate and control effect survey: Rice seedling rot disease is prone to occur during the rice seedling stage. Therefore, the experiment began with sowing on March 10th, and the rice seedling emergence in each treatment area was observed on March 25th. The occurrence of rice seedling rot disease was investigated 15 days and 24 days after emergence. The initial emergence rate survey used 70% of the emergence rate in the control area as a baseline to begin calculating the rice seedling emergence rate for each treatment. Secondly, 30 representative rice plants were selected from each treatment area to investigate plant height, root length, total number of roots, etc. Finally, the effect of the pesticide on rice seedling emergence was evaluated. To control the occurrence of rice seedling rot disease, 30 hills were surveyed for each treatment, and the total number of plants surveyed and the number of diseased plants were recorded to facilitate the calculation of the incidence rate and control effect.

[0163] The data were statistically analyzed using EXCEL and SPSS software, and the Duncan's New Multiple Range (DMRT) method was used to analyze the experimental data.

[0164] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100

[0165] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0166] Control efficacy (%) = (Disease incidence in control area after treatment - Disease incidence in treated area after treatment) / Disease incidence in control area after treatment × 100

[0167] Table 8 Effects of different treatments on rice seed germination and emergence.

[0168]

[0169]

[0170] Note: Lowercase letters indicate significant differences (P < 0.05).

[0171] Table 9. Control effects of different treatments on rice seedling blight.

[0172]

[0173] Note: Lowercase letters indicate significant differences (P < 0.05), and uppercase letters indicate significant differences (P < 0.01).

[0174] Observations in Tables 8 and 9 show that the 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension significantly promoted the germination and growth of rice seeds. Compared with the control agent and the water control, the rice seeds treated with the 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension had a seedling emergence rate of 97.29% and a seedling establishment rate of 95.15%, both superior to the control group. Furthermore, the treated rice seeds showed significantly better growth in later stages, with superior plant height, underground root length, root number, and total fresh weight compared to the other control groups, and the overall growth was also more uniform. In addition, an investigation into the control efficacy against rice seedling rot at 15 and 24 days after emergence revealed that this combination effectively controlled the occurrence of rice seedling rot and showed the best effect compared to other agents, with control efficacies of 83.79% and 89.37%, respectively. Therefore, the above analysis shows that the reasonable combination of these three compounds has an excellent synergistic effect. Furthermore, no phytotoxicity occurred during the entire application process, making it safe to use.

[0175] Example 3: Field efficacy trials of metalaxyl, thiamethoxam, and fluopyram against peanut damping-off 3.1 Test agents and treatments

[0176] Same as "Table 4 Test Reagents and Treatments".

[0177] 3.2 Test Methods

[0178] Peanut variety tested: Haihua No. 1

[0179] Experimental site: Zhumadian, Henan Province. The previous crop was corn. The soil was sandy loam with a pH of 6.7 and moderate fertility. Peanuts were planted using the same method: manual ridging, with ridges 55cm wide and 20cm high, double rows per ridge, and holes spaced 20cm apart, with 2 seeds per hole. Soil, cultivation, and water and fertilizer management conditions were consistent across all experimental areas.

[0180] Experimental Design: The experiment included five treatments: 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension, 200 g / L fluoxadiazon seed treatment suspension, 5% thiamethoxam SC, 10% metalaxyl-mancozeb seed treatment suspension, and a water control (CK). The seed treatment ratio was as described in Table 4 above. All treatments were applied as a single seed treatment 3 days before sowing, strictly adhering to the commonly used concentrations or dosages of each pesticide. For each treatment, 5 kg of peanut seeds were weighed and placed in a seed treatment machine, then water was added at a machine-to-seed-pesticide ratio of 1:100. The mixture was thoroughly mixed with the seeds, dried, and then sown. A randomized block design was used, with four replicates per treatment and a plot area of ​​30 m². 2 .

[0181] 3.3 Survey Methods

[0182] Emergence rate survey: Seed treatment was carried out on April 15, 2024, and sowing was completed on April 17. After sowing, the emergence rate of each treatment was observed and recorded regularly; on May 3, 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.

[0183] Control efficacy survey: During the peanut seedling stage, a 5-point "Z" shaped sampling method was used, with 30 plants surveyed per plot to investigate the occurrence of peanut damping-off in the field. The number of diseased plants was counted, and the incidence rate and control efficacy were calculated. The classification standards for peanut damping-off are as follows:

[0184] Grade 0: Disease-free, healthy plants, with no lesions or symptoms;

[0185] Level 1: Mild disease, with a small number of lesions on the plant, and the lesion area accounting for less than 5% of the total plant area.

[0186] Level 2: Moderate disease, with numerous lesions on the plant, covering 5% to 25% of the total plant area.

[0187] Level 3: Severe disease, with numerous lesions on the plant, covering 25% to 50% of the total plant area.

[0188] Level 4: Extremely severe disease. The plant has very serious lesions, covering more than 50% of the total plant area. Some plants may have already died.

[0189] 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.

[0190] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100

[0191] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0192] Disease index = 100 × ∑(number of diseased plants at each level × relative level value) / (highest disease level × total number of plants surveyed)

[0193] Control efficacy (%) = (Disease index in control area - Disease index in drug-treated area) / Disease index in control area × 100

[0194] 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.

[0195] Yield increase rate (%) = (pod yield in treatment area - pod yield in control area) / pod yield in control area × 100 Table 10: Efficacy of different treatments on peanut field emergence rate and control of peanut damping-off disease

[0196]

[0197] Note: The actual field control efficacy of 10% metalaxyl seed treatment suspension for controlling peanut damping-off, combined with indoor toxicity testing, was not significantly different from the control (CK) and can be disregarded.

[0198] Table 11 Effects of different treatments on peanut yield

[0199]

[0200] Note: Lowercase letters indicate significant differences (P < 0.05), and uppercase letters indicate significant differences (P < 0.01).

[0201] Observations in Tables 10 and 11 show that the 7% metalaxyl-M·thiamethoxam·fluoxadiazon seed treatment suspension exhibits the best control and yield-increasing effects against peanut damping-off, with a control efficacy of 92.66%. Compared to the control group (CK), the yield increase rate is 16.68%, significantly better than other control groups. Furthermore, this combination of agents significantly reduces the incidence of diseased plants and effectively increases the peanut emergence rate to 96.35%. Therefore, the above analysis demonstrates that the rational combination of these three compounds has a good synergistic effect. Moreover, no phytotoxicity was observed during the entire application process, indicating safe use.

[0202] Example 4: Field efficacy trials of metalaxyl, thiamethoxam, and fluopyram against maize stalk rot 4.1 Test agents and treatments

[0203] Same as "Table 4 Test Reagents and Treatments".

[0204] 4.2 Test Methods

[0205] The maize variety tested was Zhengdan 958.

[0206] Experimental site: Xinxiang, Henan Province. The previous crop was maize. The soil was brown loam with a pH of 6.7 and an organic matter content of 12 g / kg. The soil, cultivation, and water and fertilizer management conditions were consistent across all experimental areas.

[0207] Experimental Design: The experiment included five treatments: 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension, 200 g / L fluoxadiazon seed treatment suspension, 5% thiamethoxam SC, 10% metalaxyl-mancozeb seed treatment suspension, and a water control (CK). The seed treatment ratio was as described in Table 4 above. All treatments were applied once before sowing, with the dosage strictly adhering to the commonly used concentrations or dosages of each pesticide. For each treatment, the same weight of corn seeds was weighed and placed in a seed treatment machine. Water was added at a machine-to-seed-pesticide ratio of 1:50, and the mixture was thoroughly mixed with the seeds. After drying, the seeds were sown. A randomized block design was used, with four replicates per treatment. Each plot was 15 m long and 3 m wide (5 rows), with an area of ​​45 m². 2 3.3 Survey Methods

[0208] Emergence rate survey: Seed treatment was performed on April 17, 2024, and sowing was completed on April 18. After sowing, the emergence status of each treatment was observed and recorded regularly. Once all seedlings had emerged, the emergence rate and plant height of the maize were tallied on May 8. Five points were randomly selected from each plot, with each point covering an area of ​​4m². 2 The effects of each agent on corn emergence rate were evaluated and the growth of corn was observed.

[0209] Control efficacy survey: At the late milk stage of maize, a 5-point "Z"-shaped sampling method was used, with 30 plants surveyed in each plot to investigate the occurrence of maize stalk rot in the field. The number of diseased plants was counted, and the incidence rate and control efficacy were calculated. The disease classification standards for maize stalk rot are as follows:

[0210] Grade 1: The whole plant is growing normally, but the middle and lower leaves show symptoms of wilting / yellowing. The stem base is growing normally, and the fruit bunches are growing normally.

[0211] Level 3: All leaves of the plant show signs of wilting, but the stem base and fruit ears grow normally.

[0212] Level 5: The leaves of the whole plant show typical symptoms of wilting, the base of the stem is discolored and slightly water-soaked, and the fruit bunches are basically normal.

[0213] Level 7: The leaves of the plant show typical symptoms of wilting, the base of the stem is obviously softened but does not fall over, the ears of fruit droop, and the kernels are not plump.

[0214] Level 9: The entire plant dies and falls over, the vascular bundles at the base of the stem are ruptured, and the seeds are shriveled.

[0215] Table 12 Resistance Evaluation Criteria (Based on Population Disease Rate)

[0216] Disease incidence 40.1％～100％ 30.1％～40.0％ 10.1％～30.0％ 5.1％～10.0％ 0～5.0％ level extremely weak weak middle powerful Extremely strong code 1 3 5 7 9

[0217] 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.

[0218] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100

[0219] Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100

[0220] Control efficacy (%) = (Disease incidence in control area after treatment - Disease incidence in treated area after treatment) / Disease incidence in control area after treatment × 100

[0221] After the corn matured, measurements were taken in four replicates per treatment plot, with each replicate being 45 m. 2 The average yield of corn was calculated, and then the actual yield per hectare was calculated to determine the yield increase rate.

[0222] Yield increase rate (%) = (Production in treatment area - Production in control area) / Production in control area × 100

[0223] Table 13. Control efficacy of different treatments on maize plant height, emergence rate, and maize stalk rot in the field.

[0224]

[0225] By observing Table 13, it can be concluded that: 15 days after corn sowing and during the milk stage of corn, the plant height, emergence rate, disease incidence, and control efficacy of different treatments were investigated. The results showed that the blank control had a plant height of 28.74 cm, an emergence rate of 81.56%, and a disease incidence of 36.56%. The plant height and emergence rate of each treatment were higher than those of the blank control, while the disease incidence was lower than that of the blank control. Among them, the 7% metalaxyl-mancozeb-thiamethoxam-fluopyram seed treatment suspension showed the best corn growth, emergence, and disease control effects, significantly outperforming other agents. The measured plant height was 30.28 cm, the emergence rate was 93.13%, and the control efficacy was 86.32%. Based on a disease incidence rate of 5%, and referring to Table 11, it can be concluded that the 7% metalaxyl-mancozeb-thiamethoxam-fluopyram seed treatment suspension exhibits extremely strong resistance to corn stalk rot. Therefore, using this agent can effectively control or prevent the occurrence of corn stalk rot, greatly improving pesticide utilization and reducing excessive environmental pollution.

[0226] Table 14 Effects of different treatments on maize yield

[0227]

[0228] Note: Lowercase letters indicate significant differences (P < 0.05), and uppercase letters indicate significant differences (P < 0.01).

[0229] Observation of Table 14 shows that all four tested agents can increase maize yield. Among them, the 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension showed the best yield increase rate compared to the blank control, at 13.91%. The 200g / L fluoxadiazon seed treatment suspension showed the second best yield increase rate at 10.83%. The 5% thiamethoxam seed treatment suspension and the 10% metalaxyl-mancozeb seed treatment suspension were similar, at 5.69% and 7.85%, respectively. Therefore, combined with Tables 12 and 13, it can be concluded that the 7% metalaxyl-mancozeb·thiamethoxam·fluoxadiazon seed treatment suspension not only has a significant effect on the control of maize stalk rot, but also has a significant effect on increasing maize yield. Therefore, the use of this agent can help farmers increase production and income.

[0230] The seed treatment agent of this invention, through a rational formulation of metalaxyl, thiamethoxam, and fluopyram, has demonstrated a significant synergistic effect among the three agents in indoor toxicity and field efficacy trials. It effectively controls rice bakanae disease, rice seedling rot, peanut damping-off, and corn stem rot with excellent control efficacy. Simultaneously, this seed treatment agent is highly safe, has no adverse effects on crop growth, helps improve crop yield and quality, reduces the use of chemical pesticides, and lowers the risk of pathogen resistance development. It offers significant economic and ecological benefits and has broad application prospects in agricultural production.

Claims

1. A seed treatment comprising mefenoxam, thiamethoxam and fluazinam, characterized in that: The seed treatment agent is composed of an effective component and an auxiliary component, the effective component is metalaxyl-M, thiabendazole and fluazinam, and the mass ratio among the three is 1-10:1-5:1-10.

2. The seed treatment of claim 1, wherein: The mass ratio of the metalaxyl-M, thiabendazole and fluazinam is preferably 1-8:1-3:1-5.

3. The seed treatment of claim 1, wherein: The auxiliary component includes one or more of dispersing agent, wetting agent, penetrating agent, antifreezing agent, preservative, thickening agent, defoaming agent, film forming agent, coloring agent, pH regulator, deionized water.

4. The seed treatment of claim 1, wherein: The formulation form of the seed treatment agent containing metalaxyl-M, thiabendazole and fluazinam is preferably seed treatment suspension.

5. The seed treatment of claim 1, wherein: The seed treatment agent formula includes: effective component 1-30%, dispersing agent 2-5%, wetting agent 2-5%, penetrating agent 0-3%, antifreezing agent 1-5%, preservative 0.1-0.3%, thickening agent 0.1-4%, defoaming agent 0.3-1%, film forming agent 3-5%, coloring agent 3-20%, pH regulator 0-3%, and deionized water is supplemented to 100%.

6. Use of the seed treatment agent of claim 1 for controlling crop diseases, characterized in that: The seed treatment agent is used for coating and seed dressing treatment of crop seeds before seedling or sowing.

7. Use according to claim 6, characterized in that: The crop includes rice, peanut and corn.

8. Use according to claim 6, characterized in that: The crop diseases include rice seedling disease, rice seedling rot disease, peanut wilt disease and corn basal rot disease.

9. Use of the seed treatment agent of claim 1 for improving crop traits, characterized in that: The seed treatment agent is used for coating and seed dressing treatment of crop seeds before seedling or sowing.

10. The use according to claim 9, characterized in that: The crop is rice, and the improved crop traits include one or more of the following: improving the seedling emergence rate, improving the seedling rate, increasing the average plant height, increasing the average underground root length, increasing the average root number, and increasing the total fresh weight. Alternatively, the crop is peanut, and the improved crop traits include one or more of the following: improving the seedling emergence rate and increasing the pod yield per mu. Alternatively, the crop is corn, and the improved crop traits include one or more of the following: increasing the plant height, improving the seedling emergence rate, and improving the yield per mu.

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