The technical points of use of biological pesticides are as follows:
(1) Select suitable biological pesticide varieties. Different vegetable pests have different sensitivity to biological pesticides. Therefore, it is very important to select suitable bio-pesticides for different control objects. For example, cabbage caterpillar should be controlled with avermectin and BT. Beauveria bassiana does not have obvious control effect on cabbage caterpillar, while underground pests, Spodoptera litura, and beet armyworm should be controlled by Beauveria bassiana.
(2) Reasonably master the concentration of application. Different types of pests, different pests of the same pest, are not sensitive to biological pesticides. The appropriate concentration must be selected according to the sensitivity of the pests in order to receive good control effects. For example, cabbage caterpillar is more sensitive to avermectin and BT, and can be controlled by avermectin 3500-4000 times solution or BT500-1000 times solution, while Spodoptera litura is not sensitive to avermectin and BT, and it is necessary to use Avermectin. 100-200 times liquid can receive good anti-effect.
(3) Determine the appropriate period of prevention and treatment. Compared with chemical pesticides, biological pesticides play a slower effect on insecticides, so the application period must be appropriately advanced. In general, bio-pesticides are more effective against young larvae than younger larvae, so the best period of application is from the larval hatching period to the younger larval stage.
(4) Choose the appropriate climatic conditions. The biological activity of biological pesticides is related to temperature and humidity. The higher the temperature, the stronger the biological activity at the same concentration. Therefore, the biological pesticide is more suitable for use in summer and autumn with high temperature and humidity. When the temperature is above 25 °C, in order to avoid the killing of pathogenic microorganisms by strong ultraviolet rays, it is suitable to apply at about 5 pm, and it can be applied throughout the day on cloudy days. Most bio-pesticides require high humidity, so the application is better after rain. However, it must be replenished in the rain shortly after application.
(5) Standardize the method of application. Since bio-pesticide is mainly based on stomach poisoning and contact killing, it is necessary to pay attention to uniform spraying when spraying, and spray the front and back sides of the blade. In order to improve the adhesion of bio-pesticide, a little vegetable oil can be added when the avermectin solution is used. Powders and granules of BT should be applied after dew and rain in the morning and evening. For vegetable varieties with thick waxy layers, adding a little detergent powder when formulating biological pesticides is beneficial to improve the adhesion of the medicament.
(6) When mixed with a small amount of chemical agents, when large pests occur and a mixture of various pests occurs, the use of biological pesticides alone will be slow due to the efficacy of the drugs, and it is difficult to effectively control the pests. Therefore, it is necessary to be efficient, low-toxic, and low. Residual chemical pesticides are used in combination. For example, when the hybrid of Plutella xylostella and Beet armyworm occurs, avermectin can be used as a supplement, and BT plus insecticide can be used as a mixture. Note that biological pesticides cannot be mixed with alkaline pesticides and generally cannot be mixed with fungicides.
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