The use of a fumigant to prevent vegetable pests and diseases in greenhouses has the advantages of simple operation, convenience and safety, good efficacy, no increase in indoor humidity, low pesticide residues, and labor saving. The control effect is more obvious during the rainy days or epidemics, and it is an important method for preventing and controlling vegetable pests and diseases in greenhouses. However, if it is used improperly, there will be problems such as lowering of control efficiency or causing injury to medicines. Therefore, the following aspects should be taken into account when using it: 1. Choose the fumigant for symptomatic treatment. During the prevention and treatment, the targeted smoke agents should be selected according to different control objects. Currently, the commonly used fumigants are: 30% chlorothalonil smoke agent, which can prevent fungal diseases of cucumber, tomato, leeks and other crops; 20% shed fungi Smoke agent, can control downy mildew, gray mold, leaf mold, early blight, late blight, epidemic, powdery mildew, anthrax, black spot disease and other diseases; 10% smoke smoke agent can control aphids, Greenhouse whitefly, spotted fly and other pests; 10% smoked smoked agent can control red spider, two-leafhopper and other pests. If multiple pests and diseases occur, compound smoke agents can be used for prevention and control. 2. Strictly control the amount of application. According to the size of the greenhouse space, the effective content of the smoke agent and the different growth periods of the vegetables, the appropriate dosage should be selected in accordance with the principle of economy and efficiency. Such as the control of cucumber downy mildew, disease, tomato early blight, late blight, gray mold, etc., can choose 10% procymidone smoke agent, 250 to 300 grams per acre medication, the incidence of heavy doses of indoor medicine properly increased to 400 ~ 500 grams, such as powdery mildew can choose 15% Keziling smoke agent, 250 ~ 300 grams per acre medication. To control sclerotinia, 10% quick-cyanide smoke can be used, and 250-300 g per mu can be used. In the early stage of vegetable growth, due to thin and tender seedlings, it is easy to cause phytotoxicity, and the dosage should be reduced as appropriate. 3. Reasonably manage the application time. According to the characteristics of vegetable production in the greenhouse, it is best to apply the aerosol agent in the evening after sunset so that it can be smoked during the night, because it is more conducive to the settlement of the mist particles of the smoke agent during this period, and the control effect is more ideal. In the event of cloudy, rain, snow weather, the daytime can be carried out as usual. 4. Correctly grasp the method of application. The smoke agent should be deployed at multiple points, and the distribution should be uniform. Use iron wire, bricks (blocks of wood, bamboo sticks) as the support, and place the smoke agent at a height of 20 to 50 cm from the ground. When it is discharged, it should be from inside to outside. Ignite in order, pay attention to blow out the open flame, make it normal smoke. The shed film was then promptly sealed overnight. After ventilation the next morning, personnel were allowed to enter the shed for agricultural operations. In the rainy days, it should be sealed for 4 to 6 hours after application in the daytime before it can be released. 5. Determine a reasonable number of medications. According to the severity of the occurrence of pests and diseases, the number of medications should be determined, and the prevention and treatment of diseases should be applied at the initial stage of disease. In the early stage of disease, only one discharge can be achieved to achieve the control effect. In the middle and later stages of the disease, it is usually used once every 7 to 10 days, once every 2 to 3 times. If the pests and diseases are serious or the sealing performance of the booth is poor, the dosage may be increased or the application interval may be shortened. Life Vest Jacket,Inflatable Life Vest,Water Rescue Life Vest,Water Rescue Life Jacket jiangyin chenyi medical technology co.,ltd , https://www.chenyimed.com