How to Scientifically Prevent and Control Viral Disease in Mustard Greens

Mustard greens (Brassica juncea) is an annual or biennial herbaceous plant of the genus Brassica in the family Brassicaceae. It is a well-known specialty vegetable of China, originating in China, and a common vegetable cultivated throughout the country, mostly distributed in the provinces south of the Yangtze River. The main and lateral roots of mustard greens are distributed within about 30 cm of the soil layer, and the stem is a shortened stem, with leaves borne on the shortened stem in shapes such as elliptical, ovate, obovate and lanceolate, and leaf colors of green, dark green, light green, yellow-green, green with stripes, or purplish red. It is rarely cultivated in European and American countries, having originated in Asia. Li Shizhen's "Compendium of Materia Medica" records the medicinal value of mustard greens. Mustard greens prefer cool and moist conditions, tolerate heat and drought poorly, and are slightly tolerant of frost. The average temperature suitable for seed germination is 25°C. The average temperature most suitable for leaf growth of mustard greens is 15°C, and the temperature most suitable for the growth of the edible organs is 8-15°C, but stem mustard and heading mustard require lower temperatures for the formation of their edible organs; generally, leaf mustard is less strict about temperature requirements.

Growth Habits of Mustard Greens

Budding, bolting, flowering and fruiting require vernalization at low temperature and long-day conditions. In both northern and southern China, autumn sowing is the main practice; in the Yangtze River basin and various areas of the southwest and south China, harvesting takes place in winter or the following spring, while in the north harvesting takes place before frost. Leaf mustard, which is eaten as young plants, can be sown in spring or summer in the south. During the growing period, long-day conditions make bolting more likely, affecting the growth of the edible organs.

Mustard greens are very rich in vitamin A, B-group vitamins, vitamin C and vitamin D. Its specific benefits include refreshing the mind and invigorating the brain; mustard greens contain a large amount of ascorbic acid, a highly active reducing substance that participates in important oxidation-reduction processes in the body, can increase the oxygen content in the brain, stimulate the brain's use of oxygen, and has the effect of refreshing the mind, invigorating the brain and relieving fatigue.

How to prevent and control viral disease in mustard greens?

What is viral disease?

Viral disease is also called "guding disease" or "choufeng disease." It can harm many cruciferous crops such as mustard greens, radish, Chinese cabbage, bok choy and cabbage. It occurs commonly throughout China and causes serious damage.

Symptoms and causes of viral disease in mustard greens:

1) Symptoms The disease can occur at all growth stages. At the beginning of the disease, the heart leaves show a pale, semi-transparent vein-clearing appearance along the leaf veins, which then turns chlorotic along the veins, becoming a mosaic of light green and dark green. The leaves become wrinkled and uneven, and sometimes brown spots or streak lesions appear on the veins. In the later stage, the leaves become hard and brittle and gradually turn yellow. In severe cases, the diseased plants become dwarfed and stop growing. The root system is poorly developed, and the cut surface is yellow-brown. When seed plants are affected, the flower stalks are deformed, the leaves are mosaic-patterned, the seed pods are thin and small, and few seeds are set.

2) Conditions for disease development This disease is a viral disease caused by infection with multiple viruses. The viruses have various ways of overwintering. Some overwinter on seeds, perennial weeds in the field, or diseased plant residues; some overwinter on seed plants; and some overwinter in protected cultivation facilities. The following year they are transmitted by aphids, contact and other means. High temperature and drought favor the occurrence of aphids and also favor the occurrence and epidemic of viral disease. The disease is severe under conditions such as continuous cropping, adjacent diseased crops, insufficient fertilizer, and poor growth. Seedlings before the 6-7 leaf stage are susceptible to infection, while susceptibility decreases after the adult plant stage. Different varieties also differ significantly in disease resistance.    Prevention and control methods for viral disease in mustard greens:

① Disease-resistant varieties Most of the new varieties bred by various breeding units in China are relatively resistant to the disease.

② Select and retain disease-free seed plants When harvesting in autumn and winter, strictly select disease-free seed plants. This can reduce the virus source for the following year and reduce seed-borne virus.

③ Arrange crop rotation reasonably Cruciferous vegetables should avoid continuous cropping or adjacent cropping to reduce sources of virus transmission.

④ Sow at the appropriate time in autumn For autumn-winter cultivation, sow late at the appropriate time. This allows the seedling stage to avoid the hot, dry season, and sowing in the cool season when the disease is unlikely to occur can reduce the incidence of the disease.

⑤ Avoid aphids at the seedling stage The seedling stage is the period when viral disease is most easily contracted, so pesticides should be sprayed promptly to prevent transmission by aphids.

⑥ Field management Deep plowing and careful cultivation, eliminating weeds, and reducing sources of infection. Apply more organic fertilizer, combined with phosphorus and potassium fertilizers, to promote robust plant growth and improve disease resistance. Strengthen water management to avoid drought. Promptly remove weak and diseased seedlings.

⑦ Timely control of aphids See the pest section for details.

⑧ Chemical control Before the disease occurs, the following agents can be used: high-fat film 200-500 times dilution; 83 disease-resistance agent stock solution 10 times dilution; Bingduning 500 times dilution; 20% Bingdujing 400-600 times dilution; antidote No. 1 300-400 times dilution. Use one of the above agents once every 7-10 days at the seedling stage, spraying 3-4 times in succession.