Crab is a common vegetable grown in many regions. During the planting process, farmers often encounter pests and diseases such as cabbage virus disease, which causes great losses to farmers. So, what should farmers do? This article will give you a detailed summary of cabbage virus diseases for farmers’ reference.
Symptoms of damage:
The mesophyll near the leaf veins becomes yellow in the seedling stage and expands along the leaf veins. Round chlorotic yellow spots or small chlorotic spots appear on some leaves, which later turn into dark and light green mottled spots. Adult plants are affected, and the young leaves show uneven shades of mottled, and there are dark brown necrotic rings on the back of the old leaves. Sometimes the leaves are shriveled, hard and brittle, and the new leaves have bright veins.
Pathogens and occurrence patterns:
Turnipmosaicvirus (TuMV) is called turnip mosaic virus; Cucumhermosaicvirus (CMV) is called cucumber mosaic virus; Tobaccomosaicvirus (TMV) is called tobacco mosaic virus.
The virus overwinters on stored cabbage and cabbage seeds, or on living host plants in the field. It can also overwinter on the ratoons of overwintering spinach and perennial weeds. The next spring, aphids spread the virus to cruciferous vegetables planted in the spring. Generally, high temperature and drought are conducive to the disease. In the seedling stage, the first six true leaves are susceptible to damage. The earlier the damage occurs, the more serious the disease will be. Viral diseases mainly occur in Shanghai and the middle and lower reaches of the Yangtze River from April to June in spring and from September to December in autumn. The second half of the year is more serious than the first half. Continuous cropping plots, adjacent to cruciferous vegetables, plots sown earlier in autumn, low-lying terrain, poor drainage, extensive management, water shortage, fertilizer deficiency, and excessive nitrogen fertilizer application are more susceptible to disease.
Prevention and control methods:
After the cultivation season, thoroughly remove diseased remains in the field and weeds on the edges of the fields, and cultivate deeply and carefully. Apply fully decomposed organic fertilizer as base fertilizer and cultivate intensively; sow seeds at the right time according to the local climate. Frequent irrigation with small amounts of water during the seedling stage can reduce the occurrence of viral diseases. In times of drought, do not squat too much. If diseased plants are found during growth, remove them promptly and take them out of the field.
At the 5-6 leaf stage of the seedling stage, pay attention to the prevention and control of aphids. The following insecticides can be used for control: 240g/L spirotetramat suspension 4000-5000 times; 10% sulfonicamid water Dispersible granules, 3000-4000 times liquid; 50% pirimicarb wettable powder, 1000-2000 times liquid; 25% imidacloprid·sembucarb EC, 2000-3000 times liquid; 10% chlorothiol wettable powder, 2000 times liquid; 3.2% nicotine and toosendanin aqueous solution 200-300 times; spray on water.
When there is no disease in the field, pay attention to the application of chemicals for prevention. In the early or early stages of the disease, the following chemicals can be used for prevention and control: 2% Ningnanmycin aqueous solution 200-400 times; 4% pyrimidine Mycin aqueous solution 200-300 times; 20% morphine hydrochloride·copper acetate wettable powder 500-700 times; 7.5% mycotoxin·morphine aqueous 500-700 times; 2.1% alkanol·sulfuric acid Copper wettable powder 500-700 times liquid; 25% copper amber·morphine wettable powder 600-800 times liquid; 3.85% triazole·copper·zinc water emulsion 600800 times liquid; 1.5% sulfur copper·alkyl· Alkanol aqueous emulsion 1000 times liquid; 3.95% ribavirin·copper·alkanol·zinc aqueous solution 500800 times liquid; 25% morphine·zinc sulfate soluble powder 500700 times liquid; 31% azazoide·morphine soluble Powder 600-800 times liquid; spray with water, spray once every 57 days depending on the condition.