Viral disease is the main disease of broccoli and it is widespread and serious. Now, the pathogenesis of the disease and its control methods are described as follows:
First, the incidence of the law
In areas where cruciferous vegetables are not grown in winter, the virus is overwintering in stored Chinese cabbage, cabbage, radish, or overwintering spinach, and cruciferous vegetables are grown in winter, and the virus is overwintering in the host. The source of the poison is transmitted to various cruciferous vegetables, such as Myzus persicae, Brassica oleracea, and Brassica oleracea, resulting in the onset of various vegetables. High temperature and drought, high ground temperature, the development of the host's root system is affected, and the resistance to disease is significantly reduced. The locusts reproduce quickly and frequently, resulting in widespread disease. If the management is extensive, the soil is dry, and there is no water or fertilizer, the onset is serious. There are differences in disease resistance among different varieties.
Second, the symptoms
The disease occurs more severely at the seedling stage. In the initial stage, small round chlorotic spots were formed on the leaves. Afterwards, the entire leaves became lighter, or there were green and mottled spots. As the disease progressed, the leaves shrank and distorted. Finally, the whole plant became necrotic. In adult plant disease, in addition to the uneven mottled appearance of young leaves, the back of the old leaves sometimes produce dark brown necrotic spots, or accompanied by vein necrosis. In the end, the diseased plant dwarf malformation, petiole twists, and the flower bulb becomes smaller. The weight is not at all.
Third, control methods
1. Choose more disease-resistant varieties for local conditions, such as Green Ridge and Gasta.
2. Reasonable, introductory, rotation, and away from other cruciferous vegetables, the timely removal of serious diseased plants was found.
3. Use insect-resistant nets to cover cultivation techniques, increase organic base fertilizers, pay attention to pouring small water and control locusts, and control the occurrence and spread of diseases.
4. In the early stage of disease, 20% virus A wettable powder 500 times fluid or 1.5% plant disease spirit emulsion 1000 times liquid may be sprayed, or compound leaf foliar fertilizer may be sprayed to inhibit the disease and enhance the disease resistance of broccoli.
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