In the rainy season of high temperature and high humidity in summer and autumn, the scallions are prone to outbreaks of the popular scallion plague, which can make the original green oily scallions become yellow spots in 2-3 days, then turn white, green onion leaves are coveted, and even rot, resulting in Serious loss.
The scallion disease mainly affects onion leaves and pedicels. In the early stage of onion disease, there are spots that are not obvious in white and white. When enlarged, it becomes grayish white spots. It spreads along the vertical direction of onion leaves and quickly becomes a long white spot. The width is more than half of the circumference of the onion tube, or even larger; causing the onion leaves to droop and wither; When the cotton is wet or the humidity is high, the disease minister produces white cotton hairy mold; when the weather is dry, the white hair disappears, but the diseased leaves can still be seen with white cotton mycelium inside the onion tube leaves.
The disease is caused by a fungus called Phytophthora nicotianae, which is a malignant infectious disease with strong pathogenicity. The bacteria are overwintered by spores or mycelium in the sick body. In the warm winter, the bacteria can be dyed for the anniversary, the onion of the seedlings. It can also carry germs. The spores of the bacteria can be spread by wind and rain. The spores produce germ tubes after germination, and penetrate the epidermis of the onion leaves to invade the host directly. Under high temperature and high humidity conditions, the onion is quickly caused, and spores are rapidly formed in the lesions. Contagion, expand the hazard, 25 ° C -32 ° C is most suitable for the onset. High temperature, high humidity and rain are continuous, the disease is the most popular; planting density is high, the terrain is low, and the water in the field is conducive to the disease; too much fertilizer is applied, the nitrogen fertilizer is heavy, and the disease is heavier when the plant is weak.
The control of scallion disease requires that the planting area be well drained, the sorghum deep trenches are prepared, the rainwater drains in time to reduce the humidity in the field; the field stalks are completely removed and the non-onion garlic vegetables are rotated, and the rational formula fertilization is used to increase the phosphorus and potassium fertilizers and trace elements. Fertilizer, avoid partial application of nitrogen fertilizer. The application of grass ash is also beneficial to improve disease resistance. Once the epidemic situation is discovered, it is necessary to hurry up immediately. Use the following agents to spray the control: frost exhaust (60% dimethomorph manganese zinc wettable powder) 800-1000 times, Tianke manganese zinc (60% wettable powder) 700-800 times , frost dew speed net (72% wettable powder) 1000-1200 times, cardinal pass (64% wettable powder) 700-800 times, retinococcus (58% wettable powder) 500-600 times, preferably each Spray once every 7 days for 2-3 consecutive times. In addition, Baikunning (40% suspending agent), ethyl phosphine aluminum manganese zinc (70% wettable powder), Jiadaning and other agents have a good control effect on the disease.
The scallion disease mainly affects onion leaves and pedicels. In the early stage of onion disease, there are spots that are not obvious in white and white. When enlarged, it becomes grayish white spots. It spreads along the vertical direction of onion leaves and quickly becomes a long white spot. The width is more than half of the circumference of the onion tube, or even larger; causing the onion leaves to droop and wither; When the cotton is wet or the humidity is high, the disease minister produces white cotton hairy mold; when the weather is dry, the white hair disappears, but the diseased leaves can still be seen with white cotton mycelium inside the onion tube leaves.
The disease is caused by a fungus called Phytophthora nicotianae, which is a malignant infectious disease with strong pathogenicity. The bacteria are overwintered by spores or mycelium in the sick body. In the warm winter, the bacteria can be dyed for the anniversary, the onion of the seedlings. It can also carry germs. The spores of the bacteria can be spread by wind and rain. The spores produce germ tubes after germination, and penetrate the epidermis of the onion leaves to invade the host directly. Under high temperature and high humidity conditions, the onion is quickly caused, and spores are rapidly formed in the lesions. Contagion, expand the hazard, 25 ° C -32 ° C is most suitable for the onset. High temperature, high humidity and rain are continuous, the disease is the most popular; planting density is high, the terrain is low, and the water in the field is conducive to the disease; too much fertilizer is applied, the nitrogen fertilizer is heavy, and the disease is heavier when the plant is weak.
The control of scallion disease requires that the planting area be well drained, the sorghum deep trenches are prepared, the rainwater drains in time to reduce the humidity in the field; the field stalks are completely removed and the non-onion garlic vegetables are rotated, and the rational formula fertilization is used to increase the phosphorus and potassium fertilizers and trace elements. Fertilizer, avoid partial application of nitrogen fertilizer. The application of grass ash is also beneficial to improve disease resistance. Once the epidemic situation is discovered, it is necessary to hurry up immediately. Use the following agents to spray the control: frost exhaust (60% dimethomorph manganese zinc wettable powder) 800-1000 times, Tianke manganese zinc (60% wettable powder) 700-800 times , frost dew speed net (72% wettable powder) 1000-1200 times, cardinal pass (64% wettable powder) 700-800 times, retinococcus (58% wettable powder) 500-600 times, preferably each Spray once every 7 days for 2-3 consecutive times. In addition, Baikunning (40% suspending agent), ethyl phosphine aluminum manganese zinc (70% wettable powder), Jiadaning and other agents have a good control effect on the disease.
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