The incidence of solitary ding disease in Chinese cabbage is high. How to reduce the loss of yield reduction?

Chinese cabbage is a native vegetable in China, which has a long history of cultivation, including two categories: heading and non-heading. Feeding on tender leaves, rosette leaves or flower stems. In winter in northern China, Chinese cabbage is a frequent visitor on the table. Therefore, "Chinese cabbage is as beautiful as winter bamboo shoots" and has high nutritional value. As the saying goes, "a hundred dishes are not as good as Chinese cabbage", which is favored by consumers and widely planted in rural areas. In fact, the symptom of Chinese cabbage mentioned above is solitary ding disease, which can occur at seedling stage and adult stage, seriously threatening the normal growth of Chinese cabbage and bringing serious economic losses to vegetable farmers. So what scientific and effective preventive measures should vegetable farmers take to avoid the loss of production reduction?

1. What is Chinese cabbage solitary disease? Chinese cabbage solitary disease, also called virus disease and convulsion disease in some places, is one of the three major diseases of cruciferous vegetables, which is universal and contagious. Once Chinese cabbage is infected with this disease, the yield loss can be less than 25%, and the diseased plant rate and yield loss of Chinese cabbage with serious disease can reach more than 50%. Therefore, we must pay attention to the prevention and treatment of parthenogenetic disease in Chinese cabbage.

The pathogen of Chinese cabbage solitary top disease is mainly turnip mosaic virus, cucumber mosaic virus, tobacco mosaic virus or cucumber mosaic virus, all of which are the same disease. The outbreak of pathogens is closely related to the ground temperature. When the soil temperature reaches 30℃, the incidence of highly susceptible Chinese cabbage varieties is twice as high as that at 15℃, and the development is the best and the infection is the fastest at 28℃. Especially in autumn, Chinese cabbage is the most susceptible to this disease. The disease not only harms Chinese cabbage, but also affects other cruciferous vegetables such as Chinese cabbage and mustard.

Second, the onset conditions and climatic reasons of Chinese cabbage solitary ding disease 1:

Climate plays an important role in the incidence and severity of the disease. When the field is relatively hot and dry, the bacteria of orphan disease will multiply and spread in large numbers. Especially in autumn, the outdoor temperature is 25℃-28℃, the soil temperature is 28℃-30℃, the soil is lack of fertilizer and water, the soil is sticky, the plant growth is weak, and the aphid density is high. Early sowing is beneficial to the spread of diseases. At the same time, if Chinese cabbage or Chinese cabbage is planted near the white vegetable garden, diseases will also prevail.

2, cultivation management reasons:

Disease-resistant varieties were not selected for sowing, the planting area planning was unreasonable, sowing was too early or too late, fertilization was insufficient, watering was not timely and daily management was extensive. All these factors provide favorable conditions for disease pathogens, which makes Chinese cabbage disease pathogens take advantage of it.

3. The main source of infection:

Cabbage orphan disease is a bacterial virus. The perennial roots of Chinese cabbage or cabbage and perennial cruciferous weeds are important places for orphan viruses to overwinter, and can also overwinter on some cruciferous vegetables cultivated in winter. When the temperature and humidity are suitable in the coming year, the infected plants will form initial infection and spread to Chinese cabbage, radish or Chinese cabbage planted in summer through aphids. After planting Chinese cabbage in autumn, aphids spread to Chinese cabbage and reinfected many times, and the incubation period of the disease was short.

Third, the symptoms of Chinese cabbage solitary disease The incubation period of Chinese cabbage solitary disease is short and the incidence range is wide. It can occur from seedling stage to adult stage of Chinese cabbage, but the degree of disease is different in different stages, and the seedling stage is the most harmful.

1, seedling stage

At seedling stage, the disease usually starts from the tender heart leaves, and the young leaves gradually turn green and yellow. At the beginning of the disease, some brown necrotic stripes or brown necrotic spots appeared on the leaves, and the leaves shrank and twisted to one side. Gradually, the heart leaves appear pale green mottled, and the green leaves are thick and dense, which leads to slow growth, serious dwarfing of plants, inability to wrap their hearts, and serious death in the later stage.

2. adulthood

Adult leaves are susceptible to diseases, early leaf shrinkage, hard texture and easy to break. In the early stage, many brown spots were produced on the leaves, brown necrotic stripes were produced on the main veins of the back of the leaves, and the diseased spots were slightly depressed. The diseased plants were obviously dwarfed and deformed, and could not form balls or loose balls. Infected late, sometimes only on one side or half of the plant, deformed by shrinkage, defoliation and defoliation, but still able to bear balls, and sometimes brown spots appear in the inner leaves; When the seed plants are infected or planted with diseased mother plants, the bolting is slow, the flower buds are short, the pedicels are shriveled, the plants are short, the new leaves and leaves are severely shriveled, the buds are poorly developed or the petals are deformed, the pods are not knotted or thin, and the seeds are not full.

4. The transmission route of Chinese cabbage's mycosis is that the pathogen of mycosis mainly overwinters on the seeds of Chinese cabbage, cabbage or radish stored in winter and the perennial roots of weeds in the field, or overwinters on cruciferous vegetables planted in winter, which will become the initial source of infection of mycosis in the coming year.

This pathogen is very important to Chinese cabbage and can harm Chinese cabbage plants. Air flow, dust or agricultural operations invade Chinese cabbage plants from wounds or stomata, which sometimes helps winged aphids to spread and reinfect many times in the field.

If the seedling stage encounters high temperature and dry weather, the disease will be more serious, because high temperature is beneficial to the reproduction of aphids and the proliferation and symptoms of the disease.

Five, the prevention and control methods of Chinese cabbage solitary ding disease 1, variety selection:

Disease-resistant varieties are the basis of disease prevention and high yield, so choose varieties that are disease-resistant and suitable for local sowing and consumption habits before sowing. Generally, green cabbage is more disease-resistant than white cabbage, and late-maturing varieties are more disease-resistant than early-maturing varieties. Farmers should carry out trial planting according to the length of the local growth period and the number of days required for the growth of this variety, and strengthen the breeding of improved varieties.

2, agricultural prevention and control:

① Soil: Before sowing, use 3 kg of 6% 666 powder per mu and spray it on the ground to reduce the number of germs;

② Good planting planning: Good vegetable planting planning is helpful to reduce the occurrence of orphan disease in agricultural areas where vegetables are mainly grown. Generally, cabbage is planted in spring, but it is more serious in summer. If Chinese cabbage is planted in spring and onion, garlic and eggplant are planted in summer, there will be fewer diseases. In addition, it is necessary to stay away from Chinese cabbage planting plots, and at the same time thoroughly remove weeds in the fields to reduce the parasitic places of viruses.

③ Sowing in time: Sowing in time, too early or too late will aggravate the occurrence of solitary ding disease, and the disease will be serious if sown early, but mild if sown late. In the range suitable for sowing, plots with fertile soil or good cultivation conditions can be sown at a later time.

④ Watering: In the years of high temperature and drought, we should pay attention to a small amount of watering at the seedling stage. Generally, we should "plant seedlings in three waters and plant trees in five waters" to maintain a balanced supply of water, avoid sudden dryness and wetness, and reduce the occurrence of virus diseases. At the same time, watering should avoid the hot weather around noon.

⑤ Fertilization: Apply sufficient decomposed organic base fertilizer, combined application of nitrogen, phosphorus and potassium, and appropriately increase the application of phosphorus and potassium fertilizer to improve the demand for elements in Chinese cabbage. Nitrogen fertilizer should be applied in a small amount for many times, with less before and more after, and topdressing in stages. Spraying 1 times of 0.3% potassium dihydrogen phosphate aqueous solution foliar fertilizer every 7-8 days during core wrapping not only improves the yield, but also improves the disease resistance of plants.

⑥ intercropping crops: Shading Chinese cabbage can reduce the occurrence of solitary top disease. Chinese cabbage can be interplanted with corn, green beans and cucumber in the shed, which on the one hand weakens the light and plays a shading role, on the other hand increases the microclimate in the field and lowers the temperature, which is not conducive to the flight of aphids, thus reducing the occurrence of solitary ding disease.

⑦ Prevention and control of aphids: According to the living habits of aphids, aphids usually fly in late July and early August every year, and the disease of Chinese cabbage is the most serious before the six-leaf stage, so it is necessary to prevent and control aphids in time.

3, chemical control:

In the early stage of Chinese cabbage disease, it is necessary to use drugs in time to prevent and control it. At the same time, the seriously ill strains should be removed immediately and sprayed with drugs to prevent the spread of the disease, but they should be cleaned and disinfected with soapy water before operation or after encountering sick seedlings.

Drugs that can be used for reference: 65438+300 times aqueous solution of 0.5% antitoxin, or 500 times aqueous solution of 20% virus net, or 500 times aqueous solution of 20% virus inactivator, or 400-600 times aqueous solution of antiviral wettable powder, etc. Spray every 5-7 days.

To sum up, the occurrence of solitary ding disease in Chinese cabbage is very common in high temperature and drought years, which can occur from seedling stage to adult stage. If it is not prevented in time, it will bring serious economic losses. Therefore, farmers should take scientific preventive measures in advance to effectively reduce the loss of production reduction. In actual production, measures such as selecting varieties, agricultural control and chemical control can be taken to prevent it, and management should also go all out to achieve high quality and high yield of Chinese cabbage.