Specific embodiments: combined toxicity of triflumid and fluthiazol in different ratios
 1.1 Drugs to be tested
 95.7% of the original drug of triflumidazol, 95% of the original drug of fluthiazol.
 1.2 Source of tested insects
 Tomato root-knot nematodes with consistent individual size and physiological state were continuously fed for 5 generations indoors.
 1.3 Two single-dose indoor toxicity assays
 The two original drugs were dissolved with a small amount of acetone by the worm soaking method, and then diluted with 0.1% Tween aqueous solution to form solutions of 5 equal concentrations, which were diluted in beakers for later use, and clear water was used as a control. Immerse tomato root-knot nematodes of the same size in the liquid medicine soaked in the insect cage for 5 seconds. After absorbing the excess liquid medicine, place them in a petri dish with a diameter of 12 cm. The dish is covered with fresh tomato roots. Each concentration treated 10 heads and repeated 4 times. A blank control was set up. at ( 27±1 ) o C kept in the light incubator for 48 hours to check the mortality rate, and those who did not respond to the worm body with a dial needle were considered dead. The mortality rate was corrected by Abbott's formula, and then according to the concentration logarithm-mortality probability value analysis (Bliss) method, the toxicity regression equation and the lethal median LC were obtained 50 value.
 2 Optimal ratio screening
 Mixing optimization was carried out by mixing in proportion (Crafte), and the best mixing ratio of triflumidazolamide and fluthiazol was screened out. 48-hour Indoor Toxicity LC of Triflumid and Fluthiazol against Tomato Meloidogyne 50 They are a and b respectively. When the two agents are mixed, they are mixed according to the following proportions to form 11 formulas, that is, a+0, 0.9a+0.1b, 0.8a+0.2b, 0.7a+0.3b, 0.6a+0.4b , 0.5a+0.5b, 0.4a+0.6b, 0.3a+0.7b, 0.2a+0.8b, 0.1a+0.9b, 0+b. Each proportioned medicinal solution was tested for toxicity according to the above-mentioned method, and the death result of tomato root-knot nematode was checked after 24 hours, and the toxicity ratio Table 1 of each proportioning was obtained.
 Table 1 LC 50 dose of triflumid with LC 50 Indoor Toxicity Test Results of Fluthiazol in Different Proportions of Doses to Meloidogyne Nematode of Tomato
 According to the results in Table 1, two single-dose LC 50 Based on the different ratios of the composition, the toxicity of root-knot nematode to tomato root-knot nematode is determined. It can be seen from the table that the mixtures of different ratios all have synergistic effects, and their actual inhibition rates are greater than or close to 50%. The toxicity ratio are greater than 1. Among them, the mixture of 0.5a+0.5b had the highest actual mortality rate.
 Therefore, the optimal ratio of the mixture is trifluoroimidinamide LC 50 50% of the value plus fluthiazol LC 50 50% of the value, the ratio of active ingredients converted into two single doses is 1:4.56. Referring to the results of the optimal ratio, actually mix with triflumid : fluthiazol = 1: 4.56 (active ingredient), and the mixed preparation is diluted with acetone to a series of concentrations with a certain gradient, and then the indoor toxicity test is carried out , toxicity regression equation for mixture determination, LC 50 And the co-toxicity coefficient and calculate the co-toxicity coefficient (CTC) according to Sun Yunpei's method. Co-toxicity coefficient CTC, the calculation formula is as follows: (Triflumid is used as the standard drug, and its toxicity index is 100):
 Toxicity index (TI) for fluthiazol = LC for triflumidazol 50 / LC of fluthiazol 50 ×100
 Actual Toxicity Index (ATI) of M = LC of Triflumid 50 /M LC 50 ×100
 Theoretical toxicity index (TTI) of M = TI of triflumidazolamide × P of triflumidazolamide + TI of fluthiazol sulfone × P of fluthiazol
 M's co-toxicity coefficient (CTC) =M's ATI/M's TTI×100
 In the formula:
 M is a mixture of different ratios of fluthiazol and triflumid
 P Fluthiazol is the proportion of fluthiazol in the mixture
 P Triflumid is the proportion of triflumid in the mixture shown in Table 2.
 Table 2 Laboratory toxicity test results of triflumid, fluthiazol and their mixture against tomato root-knot nematode
 Table 2 shows that the actual compounding with triflumid : fluthiazol = 1: 4.56 (active ingredient), and then the indoor toxicity test, the co-toxicity coefficient is 196.0131, and its synergistic effect is obvious.
 3.1 Field experiment to control corn root rot nematode