What are Rapeseed Virus Infection Disease Symptoms and Prevention?

Symptoms and Prevention of Rapeseed Virus Infection Disease

Rapeseed virus disease is not easy to cure, early prevention of aphids is the key to prevention and control, and rational use of drugs to control the disease. Speaking of viral disease, it is a disease that farmers have a headache, there is no good prevention and treatment drugs, after the onset can only slow down or inhibit the development of the bio-medical disease through viral inhibitors. 

Rapeseed virus disease can occur in the main rapeseed producing areas, and it is more severe in winter rapeseed in some areas. 

It may be milder in winter, and it will be manifested when bolting and flowering in spring. The seeds are shrivelled, and the seed setting rate and oil content of rape are reduced. Today, we will mainly talk about the occurrence rules and control methods of rape virus disease for reference.

I. Characteristics of disease symptoms and identification points

1. Harmful period

the disease can occur from the seedling stage to the carob stage, and the cotyledon to the 5-leaf stage is the most susceptible.

2. Damaged parts

Infectious diseases of the whole plant.

3. Symptoms

 Symptoms are different depending on the type of rapeseed. The symptoms of Brassica napus leaves are mainly dry spots. The leaves have yellow spots, round or nearly round, and there is a dark brown spot in the center of the lesions, which mostly occurs in old age.

The leaves spread to new leaves, and there are also macular and mosaic types. The symptoms of cabbage-type and mustard-type rapes are floral leaves. First, the leaf veins of the heart leaves are transparent, gradually chlorosis, and the leaves shrink and develop slowly.

Rape virus disease

Generally, after the rape is infected with a virus, the plant will be dwarfed, and the disease can be overwintered, and the serious disease will cause the plant's resistance to stress and it is difficult to overwinter.

After the spring, the diseased plants will gradually become symptomatic when the temperature reaches above 10 ℃, the stems will shrink and appear deformed, and the light will easily mature in advance.

It is difficult to flower and set up in severe cases, or the carobs are dense, deformed, lacking grains, and the oil content is reduced.

The whole plant may even die. In addition, the resistance of rapeseed strains infected with viral diseases is reduced, and they are susceptible to diseases such as sclerotium and downy mildew.

Sclerotinia sclerotiorum

1. Recognition points

 The symptoms of Brassica napus leaves show the symptoms of withered spots, yellow spots and mosaics, mostly from the old leaves. The symptoms of cabbage and mustard rapes show the mosaic on the new tender leaves first and the plants are dwarfed.

2. Occurrence of rapeseed virus disease

1. The causative agent of rape virus disease: it is mainly turnip mosaic virus, and the diseased plants in the Yangtze River Basin account for about 80%, followed by cucumber mosaic virus, tobacco mosaic virus and rape mosaic virus.

2. The source and spread of the virus: rape seeds can carry the virus, and cruciferous plants and weeds such as radish and cabbage can also be infected, becoming the source of initial infection. Aphids are the main vectors. Winged aphids are poisonous after sucking the juice of rape leaves. They spread the virus in rape fields by migration. In addition, agricultural operations and friction between diseased plants and healthy plants can also spread disease.

Rape aphid

3. The main factors of the epidemic: the severity of the winter rape virus disease is closely related to the incidence of rape at the seedling stage, and is affected by factors such as the source of the disease, rape varieties, sowing date, aphids, climate and environment.

Early sowing and early planting of rapeseed is prone to damage by a large number of aphids when the temperature is high in autumn and winter, and there is little rain.

If the control is not timely, it is easy to be infected with viral diseases. If the temperature rises in spring, the aphids will damage again, spreading from the poisonous diseased plant to healthy plants Virus, causing viral diseases to spread. Brassica napus is generally lighter than cabbage and mustard.

3. Prevention Methods of Rapeseed Virus Disease

Generally, the prevention of diseases is mainly based on prevention, supplemented by prevention and control, and the prevention and treatment of viral diseases is mainly controlled by the source of the virus and fitness training. If aphids damage, it is necessary to apply pesticides in time.

1. Choose disease-resistant varieties. Generally, Brassica napus has strong disease resistance and high yield. Winter rape also chooses double-low cabbage varieties, such as Fengyou 682, Zhongyou 821, Huayouza 62 and Ganyou. Za 7 is a medium antiviral disease.

2. Disinfect the seeds, soak the seeds with trisodium phosphate, or coat the seeds, which can effectively prevent sclerotium disease, virus disease, aphids, etc. at the seedling stage of rape.

3. Seeding in time. Viral diseases mainly rely on aphids to spread the virus. For example, there will be drought in autumn and winter in 2019, higher temperatures, and more aphids, which is conducive to the incidence of viral diseases. Early-maturing rape varieties should not be sown too early. Mid-late varieties can be sown early in a timely manner to reduce the chance of aphid transmission.

4. Choose planting plots, generally choose paddy field or dry land planting, try to avoid being close to cruciferous vegetable planting base, to prevent aphids from spreading poison from other crops to rape plants.

5. Strengthen field management, whether it is direct seeding or seedling transplanting, we must focus on cultivating strong seedlings and enhance resistance, such as early application of seedling fertilizers and avoid partial application of nitrogen fertilizers; open "three ditch", timely watering in case of drought, In case of rain, it can drain in time. If a diseased seedling is found in the field, it can be removed in time.

During the growth of rapeseed, according to the growth of rapeseed, fertilizers, stalks, and flower fertilizers should be applied in a timely manner. Fertilizers should be used to control nitrogen, phosphorus, and potassium. Double-low rape must be boron fertilizer, and boron fertilizer can be sprayed from bolting to early flowering.

6. Early prevention of aphids is the key to the prevention of viral diseases. Generally, the occurrence of rape aphids should be observed when the rape grows to the 3-6 leaf stage. Once there are aphids, they should be quickly treated with drugs.

For the prevention and control of aphids, acetamiprid, imidacloprid, pymetrozine, fipronil, nitenpyram, pymetrozine and other agents can be used. When the occurrence is small, acetamiprid or imidacloprid can be used. Nitenpyram and pymetrozine. You can also use the aphid's tropism to use yellow plates to trap and kill aphids.

7. Reasonable medication to control the disease. After virus disease occurs in rape, virus inhibitors such as morpholine hydrochloride, ningnanmycin, atalin, aminooligosaccharin, etc. can be selected for prevention and treatment at the early stage of the disease. Morphodine hydrochloride + Ningnan is recommended Amycin or Atalin + Kedubao is used for prevention and treatment, once every 7-10 days, 2-3 consecutive times.