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Spotted flies are a major pest that harms green onions. The larvae are mothed into the leaf, and the moth eats the fleshy tissue of the two layers of epidermis, showing a curved or chaotic tunnel, destroying the green tissue of the leaf and seriously affecting the growth of green onions.
1. Agricultural control. Remove diseased leaf remnants: During the growth period of green onions, when it is found that there are leaves that have been eaten by larvae, they should be immediately taken out of the field and buried deeply. After harvesting, clean up the remnants of the plants, use them for fertilizer or burn, reduce the source of insects, and turn the soil deeply, and try to freeze the overwintering pupae in winter;
2. Physical prevention and control. The implementation of steam high temperature disinfection of the seedling substrate can kill the spotted fly pupae in the substrate, and can also treat soil-borne diseases and underground pests; the adult spotted fly can be trapped by yellow plate during the peak period, which can play a better control effect;
3. Chemical control. The appropriate period for the prevention and control of adult insect feathering begins to start control, every 5-7 days of control once, a total of 2-3 times, the best period for medication is the sunny morning dew dry to 2 o'clock in the afternoon before the peak of adult activity, and for the middle and lower parts of the plant. Agents may use biopesticides or permissible low-toxicity pesticides. It is recommended to use 75% latent pesticides, dilute 3000 times liquid, spray; can also be controlled with 0.9% avermectin 1500 times liquid.