Radish can be cultivated in four seasons and is one of the important vegetables that people eat daily. In the process of radish planting, the species and damage degree of radish pests and diseases in different counties and different plots are different. Prevention and early prevention are the key measures to reduce the losses caused by radish pests and diseases. The current hazards are mainly "four diseases, four insects", "four diseases" are downy mildew, viral diseases, soft rot, black rot, "four insects" are whitefly, aphids, cabbage caterpillars, small Earth tiger. First, the symptoms and occurrence of the main diseases of radish 1. Downy mildew 1) Symptoms. Downy mildew mainly causes white mold layer on the back of radish leaves when the leaves are affected. The pale green spots on the front surface gradually expand into yellow-green to yellow-brown lesions. The lesions are limited by the veins and the polygons are severe. Withered. 2) Incidence conditions. Downy mildew is a fungal disease. The pathogens overwinter with the residue in the soil. In autumn, the radish of the field radishes spreads through the wind and rain. From September to October, it is rainy, exposed, wet, and when the sunshine is insufficient, the epidemic is serious, and the severely infected plots and continuous crops are seriously ill. 2, viral disease 1) Symptoms. The radish seedling stage is most susceptible to disease. The onset of the seedling stage is that the heart leaves are chlorotic along the veins, causing the leaves to produce shades of green patches to form mosaics and shrinkage. The mild diseased plants have slight symptoms of mosaic and shrinkage, and the dwarfing is not obvious; the leaves of the severely diseased plants shrink into a mass or even curl; the severely diseased plants are deformed and stunted and the roots are dysplastic. 2) Incidence conditions. Viral diseases are caused by a variety of viruses. The virus spreads in the seeds, in the field, in winter, by mites, white powder, sucking and contact, and the virus disease is serious. 3, soft rot 1) Symptoms. In the radish radish root enlargement period, the daytime with the daylight increased, the temperature increased, the radish new and old leaves wilted to the ground can be restored at night and can not be restored. Infected with this disease, the inside of the radish root is water-stained brown soft rot often has juice oozing and stench. 2) Incidence conditions. The pathogen of radish soft rot is bacteria. The bacteria mainly overwinter in diseased plant residues, seed plants, soils and under-fertilized soil-fertilized fertilizers. Invasion of radish plants from roots, leaf wounds and rips by watering, rainwater, fertilizer, etc. Spread. The pathogen can grow at temperatures between 9 ° C and 41 ° C. The optimum temperature for the growth of soft rot pathogens is 28 ° C ~ 30 ° C. The terrain is low, the drainage is poor, the soil is sticky, the planting is too early, the pests are high, and the temperature is high. Severe conditions such as wetness, poor lighting, and extensive management. 4, black rot 1) Symptoms. The radish leaves are wilted and the whole plant is killed. The diseased leaf edge has an irregular "V" shape or a round yellowish brown disease. The lesions are yellowish around, and the veins turn black and become net-like dry and fall off. At the same time, the petiole vascular bundle also turns dark brown. The pathogen grows along the vascular bundle from the petiole to the radish pith (the heart of the fleshy root), causing the root to become black and the internal dry rot to soften and form a cavity. Finally, the whole plant is dead but has no odor. 2) Incidence conditions. Black rot pathogens overwinter on seeds, seed plants and diseased plant residues in the soil. They are invaded by rainwater, watering and insects from leaf margin stomata or wounds and fissures. The terrain is low, the drainage is poor, and the weather is long. Sudden rainfall, high temperature and rain, and premature planting, heavy insects occur severely. Black rot can survive for 2 to 3 years. The suitable growth temperature of the pathogen is 25 ° C ~ 30 ° C. Second, the symptoms and occurrence of major pests 1. Whitefly. Whitefly is a white adult with a body length of 1~1.5 mm. It is mainly caused by the chlorosis and yellowing of the damaged leaves on the back of the radish leaves. At present, whitefly has become the most threatening pest in the production of radish. The main occurrence period of whitefly is 7~10 months. It has long hazard, large amount of occurrence, strong fertility, rapid reproduction, large population and clustering. The greatest harm caused by the harm of whitefly is the loss of green color of radish and seriously affect the commercial value of radish. 2, mites. Aphids include radish, peach, and soot. Radish pupa occurs in 10 years and more than 10 generations in the greenhouse. Radish mites have a tendency to concentrate on the heart and inflorescence of vegetables. Aphids can breed for 1 to 4 days at temperatures between 15 ° C and 26 ° C. Aphids have strong tropism for yellow and orange and negative for silver gray. Therefore, this feature can be used to control aphids. The radish seedling stage is a large-scale occurrence of aphids. The aphids can curl the leaves of the affected leaves, shrink the leaves and gradually die, causing the radish plants to grow short and stunted. Aphids can also spread viral diseases to make the radish skin rough and affect quality and yield. 3, cabbage caterpillars. Cabbage worm is the larva of the cabbage butterfly is a chewing mouthworm. The larvae eat the residual epidermis in the back of the leaf. When they grow up, the food intake increases and the leaves are eaten into a net or nick. In severe cases, only the veins and petioles are left to cause the radish seedlings to die. The wound caused by the larvae damaging the roots of radish can induce soft rot and cause scarring. Cabbage worms generally occur in the first three to four generations of warmth. When the temperature is between 15 °C and 25 °C, their growth, development and reproduction speed up. In the late autumn, the mature larvae will be wintering in the walls, trunks and wind barriers near the vegetable fields. . 4, small tiger. The small tiger is also called the silkworm. The small ground tigers occur in 3 to 4 generations in 1 year, and the larvae of the cockroaches or the mature larvae are wintering until the end of August to the beginning of September. The small larvae bite the heart of the radish and eat the radish leaves, and the leaves are eaten into small holes or nicks. The larvae grow up after eating, and hide in the depth of 2~6 cm from the soil at night to the ground, especially in the sky. The dew is often the most harmful, often biting off the tender stems of the radish seedlings, the heart leaves causing scars and lack of seedlings and ridges. Third, the comprehensive prevention and control of pests and diseases In view of the occurrence law of radish "four diseases, four insects" and combined with the actual operation in production, in order to improve production efficiency and control effect, it is advisable to adopt integrated prevention and control measures for foliar spray fertilizer and pest control. The time, frequency and dosage of radish spray spray are mainly determined by the growth and development of pests and diseases. In general, the autumn radish cultivation in autumn is planted on August 23~24, firstly underground pests occur. The earliest white mites begin to harm after emergence. In early and mid-September, soft rot, black rot, viral diseases begin to occur, and middle and late Downy mildew began to occur. In view of the occurrence time of the above major pests and diseases, the following points should be mastered in the comprehensive prevention and control: 1. After sowing, immediately after the smear of the head water is infiltrated, the underground pests are controlled on the ground, and the common insecticide can be mixed with the bran and sprinkled on the ground. 2. When the radish grows a true leaf, 5~6 days after emergence, if it is found, the whitefly should be sprayed immediately, and then sprayed once every 2~3 days to spray imidacloprid and acetamiprid and alternately use the medicine. If the amount of occurrence is small, the prevention and control of whitefly can be extended as long as it occurs. 3, about half a month after sowing, in the first half of September, when spraying with pesticides, add foliar fertilizer, and add agricultural streptomycin to control soft rot, black rot, etc., then spray once every 10 days. Spray 3 times. 4. Add poisonous tyrants or virus K to prevent and cure viral diseases about 20 days after sowing, and then spray 3 times every 10 days. 5, 30 days after sowing, start to control downy mildew disease plus carbendazim or toxic mycelium and other drugs, and then spray once every 10 d for 2 to 3 times. At present, the commonly used drugs for controlling whitefly mites are imidacloprid, acetamiprid, cockroach, cockroach, etc.; the drugs for controlling soft rot and black rot are mainly agricultural streptomycin, neomycin, Bacterium Kejing, Nongkang 120, etc.; the main drugs for controlling downy mildew include dystrophic acid, ethyl aluminum phosphate, anti-virus cream, chlorothalonil, decanoyl morpholine, etc. The main drugs for preventing and treating viral diseases are virus K and drug tyrant. Dragon, virus raw powder, etc. When administering the drug, it should be used according to the instructions to avoid causing fat damage. At the same time, it should be noted that avoiding long-term administration of the same drug to avoid pest and disease resistance, it is better to alternately apply different types of drugs. Low Power Ptz Camera,Wifi Cameras Waterproof,Security Camera For Home,Outdoor Wireless Security Camera Shenzhen Zuomi Technology Co., Ltd. , https://www.bkvis.com
