Vegetable pest control agricultural control method
Agricultural control of vegetable pests and diseases can reduce the cost of pest control, save labor and time, reduce environmental pollution, and improve product quality. I. Clear Garden After the harvest of vegetables, many pathogens attached to the residues of vegetables are scattered in the fields and enter the soil, becoming a source of pollution for the squat vegetables. Therefore, vegetable farmers should strengthen disease prevention and control at the later stage of vegetable growth to directly reduce the number of pathogenic bacteria. In addition, after the harvest of each vegetable, the leaves and leaves of the field were completely removed, and the roots of the vegetables susceptible to root diseases were also removed. Second, deep plowing The purpose of deep plowing is to destroy the living environment of the bacteria. Generally, it is required to plow 40 cm deep after each harvest to kill some pathogens by natural conditions such as low temperature and ultraviolet rays. Third, disinfection After the vegetables are changed, the water is poured and the plastic film is used for high-temperature disinfection after deep plowing, so that the maximum temperature of 10 cm at the soil layer reaches 70°C, which can kill a large number of germs. This is a simple and effective method of prevention and control. Fourth, change the soil For some of the more fixed, small selection of varieties and large investment and high efficiency vegetables for facilities cultivation, such as solar greenhouses, can be used to control soil-borne diseases. The plough layer topsoil was replaced and supplemented with nontoxic topsoil.
Preparation of Fenebute
1. Prepare the first intermediate
Benzaldehyde and ethyl acetoacetate into ethanol, stir at room temperature under the catalysis of organic alkali reaction with filter cake filtration after 45 ~ 50 h, after the completion of the filter with ethanol elution filter cake, dry cake solids, then ethanol filtrate concentrated to a quarter of the original volume, to cold, concentrate filtering alcohol washing, solid, merging two solid is the first intermediate; The mole ratio of benzaldehyde, ethyl acetoacetate and ethanol is 1:2.5 -3:12-15.
2. Prepare the second intermediate
The first intermediate is added to the mass concentration of 20% sodium hydroxide solution, and the reaction is stirred at 85-90°C for 2-5 hours. After filtration, the filter cake is used for filtration. After filtration, the filter cake is washed, the filtrate is combined and cooled, and the filtrate is cooled by stirring for 3h. Solid second intermediate; The mass ratio of the first intermediate to the sodium hydroxide solution is I: 1.8-2.0;
3. Prepare the third intermediate
The second intermediate was dissolved in pure acetic anhydride solution for reflux 3 ~ 5h. After the reflux, the acetic anhydride was concentrated and dissolved with toluene. After the dissolution, ammonia water was added, and the reaction took place at 60_65°C for 1 ~ 1.5 h. Filtrate, wash and dry the precipitated solid to get the solid third intermediate; The mass ratio of the second intermediate, pure acetic anhydride solution, toluene and ammonia water is 5:1-1.2:0.5-0.8:0.5-0.8;
4. Prepare Finebute
The third intermediate was dissolved in 25% sodium hydroxide solution and cooled to _5°C ~ 10°C. After cooling, sodium hypochlorite was added slowly within 15-20min for 1h reaction, followed by ice bath reaction of 0.5 ~ 1.5 h and water bath reaction of 0.5 ~ 1.5 h. Finally, the temperature was gradually increased to 60 ~ 80°C for 1-5 h, and the reaction was cooled again after completion. After cooling, hydrochloric acid was added in the ice water bath to adjust the PH to 2, and the decolorization was stirred at room temperature. After filtration, sodium hydroxide was added in the ice water bath to adjust the PH to 6-7, and the cooling was stirred for 2 hours. The mass ratio of the third intermediate, sodium hydroxide solution and sodium hypochlorite is 1.0:0.8-1.0:1.0-1.1.
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