Why does Chinese cabbage get viral disease? How to treat it?

Chinese cabbage virus disease, also known as "gu Ding disease" and "draught disease", is also called the three major diseases of Chinese cabbage with downy mildew and soft rot, which can cause about 10% yield loss in general epidemic years, more than 30% reduction in some recurrent years, and even no harvest in serious areas, seriously affecting the yield and quality of Chinese cabbage. Then why does Chinese cabbage get viral disease? How to treat it?

Why does Chinese cabbage get viral disease?

Chinese cabbage virus disease is caused by virus and transmitted by aphids in the field. The seedling stage before 6-7 leaves of Chinese cabbage is the most susceptible to disease, which is called the sensitive period of disease, and it is also the dangerous period of aphid transmission, that is, the effective transmission period. During this period, the earlier the disease is, the more serious the disease is and the greater the loss is. After sowing, Chinese cabbage encountered high temperature and drought, high ground temperature or long duration, which was conducive to the reproduction and activity of aphids, which inhibited the growth and development of Chinese cabbage root system, decreased resistance, and was easy to occur at this time. In addition, sowing early, many aphids, coupled with extensive vegetable land management, low-lying, unventilated or dry soil, serious disease when lack of water and fertilizer.

After sowing, Chinese cabbage encountered high temperature and drought, high ground temperature or long duration, root growth and development was inhibited, aboveground decay was not long, host disease resistance decreased, and virus incubation period was shortened. The peak period of aphid occurrence in spring and autumn coincided with the susceptible period of cabbage, and it was easy to occur when the temperature was 15-20 ℃ and the relative humidity was below 75%. In general, the earlier the sowing time, the earlier the infection, the more serious the disease and the greater the damage, especially the high soil and air temperature before 7 leaves, drought is the most susceptible to disease, and the disease is mild in the later stage. With cruciferous vegetables adjacent to the plot, viral diseases can be transmitted to each other, can also lead to serious disease. In addition, there were significant differences in resistance to virus disease among different cabbage varieties.

Second, how to treat Chinese cabbage virus disease?

1. Select disease-resistant varieties such as Zaoshu 5, Lubai 1, 2, 4, Xiafeng Chinese cabbage, Xiaoza 56, dwarf anti-green, March slow green, April slow green and so on.

2. It is appropriate to sow late in order to avoid the high temperature period in the seedling stage. Autumn Chinese cabbage in Zhejiang and the middle and lower reaches of the Yangtze River should generally be sown from late August to early September, and the Beginning of Autumn should be sowed in Beijing.

3. Apply sufficient base fertilizer, increase phosphorus and potassium fertilizer, and control less nitrogen application. In case of high temperature and drought in the seedling stage, it is necessary to water frequently to cool and moisturize, so as to promote the root growth of Chinese cabbage and improve the ability of disease resistance.

4. Pay attention to timely control of aphids and control aphids every 7 to 10 days before 7 leaves at seedling stage. Silver-gray shading net or 22-mesh insect control net can also be used to prevent aphids and diseases.

5. Chemical control: in the early stage of the disease, when virus inhibitors and growth inhibitors are applied together, the growth promoters can be selected as foliar fertilizer concentrate of 3000mg / kg, etc., and the virus inhibitors can be treated with 200,250 times of 2% Shike water agent, or 1000 times of 20% virus A wettable powder, or 1000 times of 1.5% virus Ling EC, or 1000 times of 1.5% Zhixianling II emulsion, or 40% of virus Bike wettable powder 1000 times. Once every 7-10 days, 3-4 times in a row.