A seed treatment agent containing isotianil, thiamethoxam and thiacloprid and its use

Abstract

The application belongs to the technical field of crop disease and pest control, and specifically discloses a ternary compound seed treatment agent containing isotianil (A), thiabendazole (B) and thiamethoxam (C) and application thereof. The seed treatment agent takes isotianil, thiabendazole and thiamethoxam as core active ingredients, the mass ratio of the three is 1-3:1-5:1-30, the total active ingredients account for 3%-40% of the total mass of the treatment agent, and the rest are auxiliary ingredients allowed to be added in agricultural production. The seed treatment agent can effectively prevent and control the damage of rice seedling blight, rice bacterial leaf streak and thrips to rice before rice seedling stage through seed coating or seed soaking, thereby significantly improving the seedling emergence rate and yield of rice seeds.

Description

Technical Field

[0001] This invention belongs to the field of crop disease and pest control technology, specifically relating to a ternary compound seed treatment agent, which is particularly suitable for the prevention and control of rice bakanae disease, rice bacterial leaf streak, and thrips pests. It can be applied to rice production through seed coating or seed soaking. Background Technology

[0002] Rice, as a major grain crop in my country, is severely affected by seedling diseases and pests, which significantly impact seedling survival rate and later yield. Rice bakanae disease, caused by *Gibberella fujikuroi*, a fungus belonging to the Ascomycota, is a typical seed-borne disease. Traditional single-agent fungicides easily lead to the development of pathogen resistance. Existing SDHI fungicides such as fluopyram require rotation with agents having different crop mechanisms to delay resistance development. Bacterial leaf streak of rice, caused by *Xanthomonas aeruginosa*, is characterized by rapid spread and difficulty in control; conventional fungicides have limited inhibitory effects on the bacteria. Thrips, a major piercing-sucking pest in rice seedlings, cause leaf chlorosis and curling by scraping and sucking rice sap. While neonicotinoid insecticides such as thiamethoxam are effective against thrips, spraying results in low utilization rates and short-lasting effects.

[0003] In existing technologies, isothiazine, as an inducible resistance fungicide, can stimulate the rice's own defense mechanisms and has a long-lasting control effect on fungal diseases. Furthermore, when combined with thiamethoxam, it exhibits a synergistic effect against rice bakanae disease and rice blast. Thiamethoxam, as a heterocyclic thiazolinone fungicide, can disrupt the cell nucleus structure of pathogens, exhibiting good inhibitory effects against both bacteria and fungi, and is highly safe with no residue risk. Thiamethoxam has systemic properties, killing piercing-sucking pests through stomach poison and contact action, but there are no reports of its combined application for seed treatment. Currently, there are no known technical solutions for combining these three fungicides for seed treatment to simultaneously control fungal diseases, bacterial diseases, and insect pests in rice seedlings. Therefore, developing a ternary compound seed treatment agent to achieve "one-mix, multiple protections," reduce pesticide dosage, and delay resistance development is of significant practical importance. Summary of the Invention

[0004] The purpose of this invention is to provide a seed treatment agent containing isothiazamine, thiamethoxam, and thiamethoxam. Through the ternary compound, it achieves synergistic effect and broadens the control spectrum. At the same time, it effectively improves the control of rice bakanae disease, rice bacterial leaf streak, and thrips, reduces the amount of pesticide used, improves the safety of rice seeds and seedlings, and solves the technical problems of narrow control spectrum and high resistance risk in the prior art.

[0005] To achieve the objectives of this invention, the technical solution adopted is as follows: One aspect of this invention relates to a seed treatment agent containing isothiazamine, thiamethoxam and thiamethoxam, wherein the active ingredients of the seed treatment agent are isothiazamine, thiamethoxam and thiamethoxam, and the mass ratio of the three is 1~3:1~5:1~30.

[0006] In the mass ratios described in this invention, the mass ratio values ​​of isothiazamide can be selected from 1, 1.5, 2, 2.5, 3, etc.; the mass ratio values ​​of thiamethoxam can be selected from 1, 2, 3, 4, 5, etc.; the mass ratio values ​​of thiamethoxam can be selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, etc. (For example, if the mass ratio value of isothiazamide is a, the mass ratio value of thiamethoxam is b, and the mass ratio value of thiamethoxam is c, then the mass ratio of thiamethoxam, tebuconazole, and thiamethoxam is a:b:c).

[0007] In one embodiment of the present invention, the mass ratio of isothiazamine, thiamethoxam, and thiamethoxam in the seed treatment agent of the present invention is preferably 3:5:30, 3:2:25, 3:1:15, 3:1:30, 2.5:4:25, 2.5:2:15, 2.5:1:30, 2:5:30, 2:3:15, 2:1:25, 1.5:4:15, 1.5:2:25, 1.5:1:30, 1:1:1, 1:5:30, 1:4:15, or 1:2:25; more preferably 1.5:2:25 or 2:5:30; and even more preferably 1.5:2:25.

[0008] In one embodiment of the present invention, the three active ingredients account for 3% to 40% of the total mass of the treatment agent, and the remainder are auxiliary ingredients that are permissible to be added in agricultural production.

[0009] 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.

[0010] In this invention, the auxiliary ingredients that may be added to the agricultural production are one or more of the following: wetting agents, dispersants, antifreeze agents, preservatives, defoamers, thickeners, warning colors, film-forming agents, stabilizers, and deionized water.

[0011] Further, the seed treatment agent comprises the following components and their weight percentages: 1%~40% active ingredient, 1%~10% wetting agent, 1%~8% dispersant, 1%~6% antifreeze agent, 0.2%~1% preservative, 0.1%~1% defoamer, 0.2%~3% thickener, 2%~15% warning color, 3%~6% film-forming agent, 0.2%~3% stabilizer, and deionized water to make up to 100%.

[0012] in: The wetting agent includes one or more of the following: sodium dodecyl sulfate, block polyether, sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, sodium dioctyl succinate sulfonate, fatty alcohol sulfate, and alkyl naphthalene sulfonate. The dispersant includes one or more of the following: lignin sulfonate, naphthalene sulfonate formaldehyde condensate, polycarboxylate, polyoxyethylene polyoxypropylene block copolymer, phosphate salt, alkylphenol polyoxyethylene ether formaldehyde condensate sulfate, sodium methylene bisnaphthalene sulfonate, and lignin derivatives. The antifreeze includes one or more of ethylene glycol, propylene glycol, glycerol, polyethylene glycol, propylene glycol methyl ether, ethylene glycol butyl ether, calcium chloride, and magnesium chloride. The preservatives include one or more of potassium sorbate, Kathon, formaldehyde, benzoic acid, sodium benzoate, sodium sorbate, isothiazolinone, and sodium dehydroacetate; The defoamer includes one or more of the following: organosilicon, polyether, mineral oil, dimethylsiloxane, polyether-modified organosilicon, polyoxyethylene polyoxypropylene glycerol ether, fatty acid ester defoamer, and organosilicon-mineral oil composite defoamer; The thickener includes one or more of xanthan gum, guar gum, sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, sodium polyacrylate, polyacrylamide, fumed silica, bentonite, magnesium aluminum silicate, and attapulgite. The warning colors include one or more of lemon yellow, sunset yellow, carmine, bright blue, water-based rose red, and magenta; The film-forming agent includes one or more of the following: polyvinyl alcohol, polyvinyl acetate emulsion, acrylate copolymer, polyurethane resin, gum arabic, chitosan, and sodium alginate; The stabilizer includes one or more of BHT, citric acid, triethanolamine, potassium dihydrogen phosphate, and titanium dioxide.

[0013] Another aspect of this invention relates to the application of the seed treatment agent in the control of crop diseases and pests. Preferably, the crop diseases are rice bakanae disease and rice bacterial leaf streak before the rice seedling stage. The crop pests are preferably thrips. More specifically, this invention relates to the application of the seed treatment agent in the control of rice bakanae disease, rice bacterial leaf streak, and thrips before the rice seedling stage.

[0014] Another aspect of the present invention relates to the use of the seed treatment agent for improving the growth traits of rice. Preferably, the rice growth traits include: emergence rate, seedling establishment rate, average plant height, average underground root length, and fresh weight per 100 plants, etc., and the seed treatment agent of the present invention can increase the above-mentioned rice growth trait indicators.

[0015] More specifically, the present invention relates to the application of the seed treatment agent in increasing rice emergence rate, seedling establishment rate, average plant height, average underground root length, and fresh weight per 100 plants.

[0016] Compared with the prior art, the advantages of the present invention are: 1. Synergistic effect: The combination of isothiazamine (inducing resistance), thiamethoxam (destroying the cell nucleus), and thiamethoxam (stomach poison, contact and systemic activity) has complementary mechanisms of action, forming a comprehensive control of fungi, bacteria and pests, and the control effect is significantly better than single agents or binary compound agents. 2. "One treatment for multiple preventions": Seed treatment enables simultaneous control of three diseases and pests during the seedling stage, reducing the number of spraying applications, significantly reducing pesticide use, and meeting the requirements of green pest control; 3. Long-lasting effect: The active ingredients are absorbed and transported through the seeds, resulting in a long-lasting effect that covers the critical control period during the rice seedling stage, thus solving the problem of short-lasting effect of conventional spraying. 4. High safety: When used at the recommended dosage, it is safe for rice seeds and seedlings, causes no phytotoxicity, and leaves no residue, making it environmentally friendly. Detailed Implementation

[0017] To better understand the purpose, technical solution, and advantages of this invention, the following detailed description of the invention will be provided in conjunction with specific embodiments. The technical solutions mentioned in the embodiments are not intended to limit the invention. The following description is only for explaining the invention. Any modifications, equivalent substitutions, and improvements made without departing from the spirit and principles of this invention should be included within the scope of protection of this invention.

[0018] I. Indoor bioassay activity determination Example 1: Screening of the ratio of isothiazine, thiamethoxam and thiamethoxam against rice bakanae disease and determination of co-toxicity coefficient. 1. Experimental materials Test target: Rice bakanae disease, caused by *Gibberella fujikuroi*, a fungus belonging to the Ascomycota. Provided by the Plant Pathology Laboratory, Department of Plant Protection, Fujian Agriculture and Forestry University.

[0019] Test reagents: 96% isothiazine technical grade (Bayer AG), 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 98% thiamethoxam technical grade (Shanghai Heteng Fine Chemical Co., Ltd.).

[0020] The test culture medium was potato dextrose agar (PDA) medium.

[0021] 2. Test treatment Dosage setting: The test agents isothiazamine, thiamethoxam and thiamethoxam were prepared into stock solutions with acetone, and then separated with 2% Tween 80 sterile water. Isothiazamine, thiamethoxam and thiamethoxam were then compounded in 17 different ratios, namely 3:5:30, 3:2:25, 3:1:15, 3:1:30, 2.5:4:25, 2.5:2:15, 2.5:1:30, 2:5:30, 2:3:15, 2:1:25, 1.5:4:15, 1.5:2:25, 1.5:1:30, 1:1:1, 1:5:30, 1:4:15 and 1:2:25. 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).

[0022] Experimental replication: Each concentration treatment was replicated 3 times.

[0023] 3. Test Methods Referring to the "Agricultural Industry Standard of the People's Republic of China NY / T1156.2-2006", the mycelial growth rate method was used. Pre-prepared mycelial blocks were inoculated onto PDA medium plates with different concentrations of pesticides and cultured at 26℃ for 4 days. The colony diameter was measured using the cross-crossing 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 following specific calculation method: Using a single agent from the mixture as the standard reagent (usually EC) 50 (The lower one), calculate: Single-dose toxicity index = standard agent EC 50 / A single-dose EC 50 ×100 Actual toxicity index (ATI) = EC of standard single dose 50 EC values / mixtures 50 value × 100 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 Cotoxicity coefficient (CTC) = Measured toxicity index / Theoretical toxicity index × 100 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.

[0024] Table 1. Results of toxicity tests of different ratios of isothiazine, thiamethoxam, and thiamethoxam against rice bakanae disease.

[0025] Table 1 shows that the EC50 of isothiazine, thiamethoxam, and thiamethoxam against rice bakanae disease was determined using the mycelial growth rate method. 50 The concentrations were 6.983 mg / L, 4.635 mg / L, and 213.482 mg / L, respectively. When the mass ratio of the three active ingredients was 1–3:1–5:1–30, the co-toxicity coefficients of the three active ingredients against rice bakanae disease in the laboratory were all greater than 120, indicating a significant synergistic effect. Especially at a mass ratio of 1.5:2:25, the co-toxicity coefficient was the highest at 178.70, showing the best synergistic effect. Therefore, the optimal ratio of 1.5:2:25 was selected for subsequent field efficacy testing.

[0026] Example 2: Screening of the ratio of isothiazine, thiamethoxam and thiamethoxam against bacterial leaf streak in rice and determination of co-toxicity coefficient. 1. Experimental materials Test target: Bacterial leaf streak of rice, caused by *Xanthomonas oryzae* pv. oryzicola, a serious bacterial disease of rice. Provided by the Plant Pathology Laboratory, Department of Plant Protection, Fujian Agriculture and Forestry University.

[0027] Test reagents: 96% isothiazine technical grade (Bayer AG), 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 98% thiamethoxam technical grade (Shanghai Heteng Fine Chemical Co., Ltd.).

[0028] Test medium: NA medium.

[0029] 2. Test treatment Dosage setup: The test agents isothiazamine, thiamethoxam, and thiamethoxam were each prepared as stock solutions with acetone, and then separated by dehydration with 2% Tween 80 sterile water. Isothiazamine, thiamethoxam, and thiamethoxam were then compounded in 17 different ratios: 3:5:30, 3:2:25, 3:1:15, 3:1:30, 2.5:4:25, 2.5:2:15, 2.5:1:30, 1:1:1, 1:5:30, 1:4:15, 1:2:25, 2:5:30, 2:3:15, 2:1:25, 1.5:4:15, 1.5:2:25, and 1.5:1:30. A culture medium without the agents was used as a blank control (sterile water containing 2% Tween 80 was used instead of water).

[0030] 3. Test Methods The inhibition zone method was used to determine the antibacterial effect of different proportions of the agents on the pathogen. A suspension of *Xanthomonas oryzae* with an OD600 of 0.8 was prepared. When the culture medium temperature dropped to approximately 40℃, the prepared suspension was mixed thoroughly with NA medium at a volume ratio of 1:10 to form mixed culture plates. Then, different proportions of the test agents were prepared. Subsequently, three 7mm diameter sterile filter paper discs were placed in 9cm diameter bacterial culture plates. 10µl of each of the different agent ratios was dropped onto the paper disc, with each treatment repeated three times. Sterile water served as a blank control. After incubation at 28℃ for 48 hours, the diameter of the inhibition zone was measured using the cross-hatching method. Changes in the inhibition zone were observed after 3 days. The inhibition rate of each agent treatment on the pathogen was calculated using the following formula, and the EC50 of each treatment on the pathogen was determined. 50 .

[0031]

[0032] Then, following Sun Yunpei's method, the EC values ​​of each treatment were measured. 50 Convert to Actual Toxicity Index (ATI); calculate the Theoretical Toxicity Index (TTI) based on the formulation ratio of the mixture, and calculate the Co-toxicity Coefficient (CTC) of the mixture according to the following formula, with the specific calculation method being the same as in Example 1. Table 2. Toxicity test results of different ratios of isothiazine, thiamethoxam, and thiamethoxam against bacterial leaf streak in rice.

[0033] Table 2 shows that the EC50 of isothiazine, thiamethoxam, and thiamethoxam against bacterial leaf streak of rice was determined using the inhibition zone method. 50The concentrations were 12.198 mg / L, 1.437 mg / L, and 168.552 mg / L, respectively. When the mass ratio of the three active ingredients was 1–3:1–5:1–30, the co-toxicity coefficients of the three active ingredients against bacterial leaf streak in the laboratory were all greater than 120, indicating a significant synergistic effect. Especially at a mass ratio of 1.5:2:25, the co-toxicity coefficient was the highest at 185.97, demonstrating the best synergistic effect. Therefore, the optimal ratio of 1.5:2:25 was selected for later field efficacy testing.

[0034] Example 3: Toxicity determination of thrips by different ratios of isothiazine, thiamethoxam and thiamethoxam 1. Test conditions 1.1 Test insect source and pesticide The test insects were randomly collected from the Yongyou 4949 rice variety in the rice planting base of Longtian Town, Fuzhou City, Fujian Province. Healthy adult insects with relatively uniform size were selected for the test.

[0035] Test reagents: 96% isothiazine technical grade (Bayer AG), 95% thiamethoxam technical grade (Shaanxi Xida Huate Technology Industry Co., Ltd.), 98% thiamethoxam technical grade (Shanghai Heteng Fine Chemical Co., Ltd.).

[0036] Dosage setup: The test agents isothiazamine, thiamethoxam, and thiamethoxam were each prepared as stock solutions with acetone, and then separated by dehydration with 2% Tween 80 sterile water. Isothiazamine, thiamethoxam, and thiamethoxam were then compounded in 17 different ratios: 3:5:30, 3:2:25, 3:1:15, 3:1:30, 2.5:4:25, 2.5:2:15, 2.5:1:30, 1:1:1, 1:5:30, 1:4:15, 1:2:25, 2:5:30, 2:3:15, 2:1:25, 1.5:4:15, 1.5:2:25, and 1.5:1:30. A culture medium without the agents was used as a blank control (sterile water containing 2% Tween 80 was used instead of water).

[0037] 1.2 Spray Test Method The experiment was conducted on May 24, 2025, in the Insect Laboratory of the Department of Plant Protection, Fujian Agriculture and Forestry University. Different proportions of pre-prepared pesticides were evenly sprayed onto the leaves of plants carrying thrips. After treatment, the plants were placed in an environment with a room temperature of 23–31℃ and a humidity of 84%–97% for 48 hours. Mortality was then checked; thrips that could not move when lightly touched with the tip of a paintbrush were considered dead. Each treatment consisted of 30 thrips, and the experiment was repeated three times.

[0038] The specific calculation method is as follows: Using a single agent from the mixture as the standard reagent (usually selected by LC) 50 (The lower one), calculate: Single-dose toxicity index = LC50 of standard reagent 50 A single-dose LC 50 ×100 Actual Attractive Toxicity Index (ATI) = LC of a single standard dose 50 LC of values / mixtures 50 value × 100 Theoretical Toxicity Index (TTI) = Toxicity index of fungicide A × Proportion of fungicide A in the mixture + Toxicity index of insecticide B × Proportion of insecticide B in the mixture Cotoxicity coefficient (CTC) = Measured toxicity index / Theoretical toxicity index × 100 Co-toxicity coefficient classification: when CTC≥120, the mixture exhibits a synergistic effect; when CTC≤80, it exhibits an antagonistic effect; and when CTC is between 80 and 120, it exhibits an additive effect.

[0039] Table 3. Toxicity test results of isothiazine, thiamethoxam and thiamethoxam against thrips at different ratios.

[0040] Table 3 shows that the EC50 of rice pest thrips was measured using a bioassay. 50 The effective concentrations were 42.186 mg / L, 35.458 mg / L, and 8.715 mg / L, respectively. When the mass ratio of the three active ingredients was 1–3:1–5:1–30, the co-toxicity coefficients against rice thrips after combination were all greater than 120, indicating a significant synergistic effect. Especially at a mass ratio of 1.5:5:25, the co-toxicity coefficient was the highest at 173.73, demonstrating the best synergistic effect. Therefore, the optimal ratio of 1.5:2:25 was selected for subsequent field efficacy testing.

[0041] II. Field efficacy trials Based on the above examples of indoor toxicity tests of isothiazine, thiamethoxam, and thiamethoxam against rice bakanae disease, rice bacterial leaf streak, and rice thrips, it was found that the optimal control effect against the two diseases and pests was achieved when the mass ratio of the three active ingredients was 1.5:2:25. Therefore, a seed treatment suspension was prepared according to this ratio for subsequent field efficacy trials to fully demonstrate the control effect of the compound composition involved in this invention.

[0042] Homemade medicine example 1: (1.5+2+25)% Isothiazine·Thiamethoxam·Thiamethoxam, Seed Treatment Suspension Concentrate

[0043] Homemade medicine example 2: 5% Thiamethoxam, Seed Treatment Suspension

[0044] Homemade drug example 3: 18% Isothiazine, Seed Treatment Suspension

[0045] Preparation method of seed treatment suspension: The active ingredients, auxiliary ingredients (excluding film-forming agent and warning color) and deionized water are accurately weighed according to the proportion, and then homogenized and dispersed by high-speed shearing. After 30 minutes, zirconium beads with a weight ratio of 1:1.3 are added and the mixture is milled for 1.5 hours. The mixture is then filtered to obtain a white slurry. Finally, the film-forming agent and warning color are added according to the formula proportion and homogenized and stirred for 30 minutes. After mixing evenly, the desired seed treatment suspension is obtained.

[0046] Example 1: Field efficacy trials of different agents against rice bakanae disease, rice bacterial leaf streak, and thrips. 1.1 Test reagents and treatment Table 4 Test reagents and treatments

[0047] 1.2 Test Methods Rice variety tested: Yongyou 4949 Experimental site selection: The experimental site was located in Longkou Town, Fujian Province. The soil in the experimental field was clay loam with moderate fertility and a pH value of 6.53. The previous crop was rice, and rice bakanae disease and rice bacterial leaf streak occurred every year. The cultivation and field water and fertilizer management conditions were the same.

[0048] Experimental design: The experiment included five treatments: 28.5% isothiazine·thiamethoxam·thiamethoxam seed treatment suspension, 18% isothiazine seed treatment suspension, 5% thiamethoxam seed treatment suspension, 30% thiamethoxam seed treatment suspension, and a water control (CK). The ratio of the drug to the seed was as shown in Table 4 above.

[0049] Seed dressing: Mechanical seed dressing. On May 13, one day before sowing, add 3 kg of rice seeds to be dressed for each treatment into the seed dressing machine. Dilute the agent with water at 3% of the seed weight to form a slurry, then pour it into the seed dressing agent to ensure that the agent and seeds are fully mixed evenly. Finally, spread them out to dry for 2 hours before use.

[0050] Sowing: On May 14th, rice seeds were placed in transplanting trays, with 25 trays set up for each treatment. One tray was also set up separately for observing the rice germination rate. Each tray contained 100 rice seeds. Specific procedures: First, the substrate was evenly distributed in the trays, then the seeds were sown, covered with the substrate, and placed in the seedbed. The trays were then covered with non-woven fabric. After 15 days, the non-woven fabric was removed for hardening off the seedlings. After 3 days of hardening off, the rice seedlings were transplanted into the field.

[0051] 1.3 Survey Methods Emergence rate survey: 15 days after sowing, observe the emergence, plant height, root length, etc. of rice seeds under each treatment agent, and calculate the emergence rate.

[0052] Disease survey: 15 days and 30 days after transplanting, survey 50 hills per treatment, record the total number of plants and the number of diseased plants, and calculate the disease incidence rate and control efficacy. The specific disease classification standards for rice bakanae disease and rice bacterial leaf streak are as follows: Grading standards for rice seedling blight: Grade 0: Disease-free plants with a disease incidence rate of 0%.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] Grading standards for bacterial leaf streak of rice: Grade 0: Leaves show no disease spots; Grade 1: The leaves have only small, transparent water stains, accounting for less than 1% of the leaf area; Grade 3: The leaves have scattered short and narrow striped spots, covering 1% to 5% of the leaf area; Level 5: Numerous leaf spots, covering 6% to 25% of the leaf area; Grade 7: Dysfunction spots are dense on the leaves, covering 26% to 50% of the leaf area; Level 9: The leaves are covered with dense lesions, accounting for more than 51% of the leaf area. The leaves turn orange-brown, curl, and die.

[0059] Thrips pest survey: 30 days after transplanting (i.e., after investigating the control effect on thrips 30 days after pesticide application on the two diseases), a parallel skip method was used to survey 10 points, each 0.1m in diameter. 2The total number of leaves (fully expanded leaves) and the number of leaves with rolled tips were investigated in the rice plantation, and the tip rolling rate was calculated. At the same time, the number of live thrips was investigated, and the insect control effect was calculated.

[0060] After statistically recording the diseased plants according to the relevant national field trial standards, the disease index, disease control effect, and insect control effect were calculated. The significance of the control effect was analyzed using Duncan's multiple range test (DMRT).

[0061] Emergence rate (%) = Number of seedlings germinating in one treatment / Total number of seedlings surveyed × 100 Disease incidence rate (%) = (Number of diseased plants / Total number of plants surveyed) × 100 Disease index = 100 × ∑(number of diseased plants at each level × relative level value) / (highest disease level × total number of plants surveyed) Disease prevention efficacy (%) = (Disease index in control area - Disease index in drug-treated area) / Disease index in control area × 100 Insect control efficacy (%) = (Tilt curl rate (insect quantity) in blank control area - Tilt curl rate (insect quantity) in pesticide-treated area) / Tilt curl rate (insect quantity) in blank control area × 100 Table 5 Effects of different treatment agents on rice emergence rate

[0062] Table 5 shows that different treatment agents all have a certain promoting effect on rice seedling emergence rate. Among them, the seedling emergence rate of rice seeds treated with 28.5% isothiazine·thiamethoxam·thiamethoxam seed treatment agent is the best at 96.33%, and the corresponding rice seedling rate is also better than other agents at 92%. The average plant height is 13.27 cm, the average underground root length is 11.42 cm, and the fresh weight of 100 plants is 12.53 g, all of which are better than other control agents.

[0063] Table 6. Control effects of different pesticide treatments on rice bakanae disease, rice bacterial leaf streak, and thrips.

[0064] Table 6 shows that after treating rice seeds with four different agents and a blank control, the 28.5% isothiazine·thiamethoxam·thiamethoxam seed treatment suspension, the 18% isothiazine seed treatment suspension, and the 5% thiamethoxam seed treatment suspension showed good control effects against rice bakanae disease and rice bacterial leaf streak. Among them, the 28.5% isothiazine·thiamethoxam·thiamethoxam seed treatment suspension showed the best control efficacy, with control efficacies of 92.94% and 87.90% and 95.33% and 91.74% for the two diseases at 15 days and 30 days after transplanting, respectively. The 5% thiamethoxam seed treatment suspension showed the second best control efficacy, with efficacies of 87.88% and 76.85% and 88.67% and 82.32%, respectively, while the 18% isothiazine seed treatment suspension showed efficacies of 85.65% and 71.47% and 82.38% and 76.77%, respectively. The 30% thiamethoxam seed treatment suspension showed the worst control efficacy against both diseases, similar to the control (CK). Finally, a field survey of thrips control in the treated areas revealed that rice treated with the 28.5% isothiazine·thiamethoxam·thiamethoxam seed treatment suspension achieved a field control efficacy of 87.05% against thrips, significantly better than the 64.03% efficacy of the single-agent 30% thiamethoxam seed treatment suspension. The other two agents, 18% isothiazine seed treatment suspension and 5% thiamethoxam seed treatment suspension, had almost no effect on thrips.

Claims

1. A seed treatment agent containing isothiazamine, thiamethoxam, and thiamethoxam, characterized in that: The active ingredients of the seed treatment agent are isothiazamine, thiamethoxam and thiamethoxam, with a mass ratio of 1~3:1~5:1~30.

2. The seed treatment agent according to claim 1, characterized in that: The three active ingredients account for 3% to 40% 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. The seed treatment agent according to claim 2, characterized in that: The permitted auxiliary ingredients to be added to agricultural production include one or more of the following: wetting agents, dispersants, antifreeze agents, preservatives, defoamers, thickeners, warning colors, film-forming agents, stabilizers, and deionized water.

6. The seed treatment agent according to claim 5, characterized in that: The seed treatment agent comprises the following components and their weight percentages: 1%~40% active ingredient, 1%~10% wetting agent, 1%~8% dispersant, 1%~6% antifreeze, 0.2%~1% preservative, 0.1%~1% defoamer, 0.2%~3% thickener, 2%~15% warning color, 3%~6% film-forming agent, 0.2%~3% stabilizer, and deionized water to make up to 100%.

7. The use of a seed treatment agent containing isothiazamine, thiamethoxam and thiamethoxam as described in any one of claims 1 to 6 for the prevention and control of crop diseases and pests.

8. The use according to claim 7, characterized in that, The preferred crop diseases are rice bakanae disease and rice bacterial leaf streak before the rice seedling stage; the preferred crop pests are thrips.

9. The application of a seed treatment agent containing isothiazamine, thiamethoxam and thiamethoxam according to any one of claims 1 to 6 in the control of rice bakanae disease, rice bacterial leaf streak and thrips before the rice seedling stage.

10. The use of a seed treatment agent containing isothiazamine, thiamethoxam and thiamethoxam as described in any one of claims 1 to 6 for improving the growth traits of rice.

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