Harmful symptoms and control methods of tobacco mosaic disease

Tobacco mosaic disease is common in all tobacco areas in the world, and it occurs in both northern and southern tobacco areas in China, especially in southern tobacco areas. from seedling stage to harvest period, the incidence of tobacco mosaic disease in the field is generally 520%, and in individual fields can be as high as 90% 100%. The loss of early disease can reach 50%, or even lose harvest. Let's take a look at the prevention and control methods of tobacco mosaic disease.

Harmful symptoms

After the tobacco plant was infected, the tissues of lateral veins and branch veins of young leaves were translucent, and the mesophyll tissues on both sides of leaf veins were light green. The virus proliferated massively in the leaf tissue, resulting in the enlargement or increase of some mesophyll cells, resulting in uneven leaf thickness, yellow and green color and mosaic shape. The degree of mottling of the posterior flower leaves increased, and there were large dark brown necrotic spots, especially the middle and lower old leaves, and the seriously diseased leaves were wrinkled, deformed and twisted. The plants with early disease had shortened internodes, seriously dwarfed, grew slowly, could not blossom and bear fruit normally and were easy to fall off. The shade fruit that can develop is small and wrinkled, the number of seeds is small and small, and most of them can not germinate.

Occurrence condition

Tobacco common mosaic disease mainly occurs from seedling bed stage to field budding stage. Temperature and light affect the disease spread and epidemic speed to a great extent. High temperature and strong light can shorten the incubation period, continuous cropping or interplanting with Solanaceae crops can increase the source of toxin, incidence and disease degree increase significantly, unsanitary cultivation is an important cause of epidemic, touching between diseased and healthy plants, applying immature organic fertilizer. Cultivation of soil with virus can aggravate virus transmission, soil hardening, dry climate, and serious disease in the land with severe nematode damage in the field.

Prevention and cure method

1. Select disease-tolerant varieties with strong growth, fast development and adapting to local conditions, such as Liao 44, 6315, Guanghuang 54,176, Nc89, G80, 8611, etc., pay attention to the breeding of high resistance varieties. Rotation should be carried out without intercropping or intercropping with Solanaceae plants, but should be rotated with Gramineae crops for 2 to 3 years. When mosaic disease occurs, it is necessary to apply available fertilizer, cultivate soil and water in time, promote the opening of straw and slice, and reduce the disease.

2. The seedbed should select plots that have not planted tobacco and Solanaceae plants for more than 2 years, far away from vegetable fields, select seeds collected from disease-free fields, or soak the seeds with 0.1% silver nitrate or 0.1% 0.2% zinc sulfate and 0.1% trisodium phosphate solution for 10 minutes to remove the virus on the seed surface and rinse the seeds repeatedly after soaking. Wash the seedlings with soap before fixing the seedlings, manage the seedlings first, and pull out the diseased plants in time.

3. To strengthen the field management, it is strictly forbidden to move the diseased tobacco seedlings into the field, and the sequence management of healthy plants before diseased plants should be carried out first. It is not suitable to smoke in the process of operation, and it is not suitable to walk and touch repeatedly in the tobacco field. Applying sufficient nitrogen, phosphorus and potassium fertilizer and spraying many kinds of trace element fertilizer in time to improve the disease resistance of the plant. After transplanting, the seedlings were properly refined and critical water was poured at the end of the cluster to promote plant growth.

4. At the initial stage of the disease, 6000-fold solution of 2% aminooligosaccharin, or high-tech 32% bromo-morpholine guanidine, 1.5% Zhishiling emulsion or 10% virus king wettable powder, 300 times and 500 times of Rib% Huayening wettable powder were sprayed to prevent and alleviate the damage of the virus.

5. Aphids play a decisive role in the transmission of tobacco common mosaic disease, and generally propagate 15-17 generations in the way of parthenogenetic viviparity in tobacco. Therefore, aphids should be sprayed on the surrounding peach orchards, vegetables and weeds every year from March to April to kill the tobacco aphids that have been or are hatching and reviving, so as to achieve the purpose of prevention.

What is the symptom of tobacco mosaic disease? Control methods of tobacco mosaic disease

Tobacco is one of the most important economic crops in China, and the occurrence of tobacco mosaic disease has seriously affected the yield of tobacco. So what are the symptoms of tobacco mosaic disease? What is the prevention and control method of tobacco mosaic disease?

Symptoms of tobacco mosaic disease

1. Common mosaic disease: infected by the virus, the tender leaves begin to develop the disease first, and the mesophyll along the veins turns yellow and bright veins appear. Then the dark or light color parts gradually expand to form yellow and green mottled (mosaic); in severe cases, the leaves become thick and uneven, forming bubble spots, leaf edges curl to the back, leaves are wrinkled and twisted, deformed, some are notched or banded. In the early stage of the disease, the plant was seriously dwarfed, the internodes were shortened, the plants did not grow and the leaves did not open.

two。 Cucumber mosaic disease: damaged by virus infection, the veins are transparent at the beginning of the disease, then become mosaic leaves, the leaves become narrow and twisted, the surface hairs fall off and lose luster. Some diseased leaf margins often curl upward, some appear yellow-green or dark green bubble spots, some leaf lateral veins show brown necrosis, or there is dark brown lightning necrosis along the veins. The plant is obviously dwarfed, the root system is poorly developed, and there are often "mosaic burning spots" in the dead leaves.

Incidence regularity of tobacco mosaic disease

1. Common mosaic disease: the virus can survive for a long time in the diseased body. It is mainly mixed with diseased residues such as soil, fertilizers, seeds and some poisonous hosts such as tomato, rape, mustard or perennial weeds. It is transmitted by juice contact, that is, the micro-wound of mechanical friction invades the host and spreads through human, wind, insect and other media: it is susceptible to disease from seedling stage to prosperous period, and the resistance is enhanced after topping. The temperature of 30 ℃ is the most suitable for the disease. Close to villages and towns, flue-cured tobacco rooms, purchase sites, roadside, vegetable fields and former tobacco fields as tobacco fields and vegetables, the disease is more serious; after transplanting, the disease is serious in the fields with poor fertilizer and water management, thin soil, consolidation, heavy stickiness, poor drainage and poor growth of tobacco plants.

two。 Cucumber mosaic disease: the virus cannot survive in dried tobacco leaves under natural conditions. It overwinters mainly in winter vegetables, vegetable plants or perennial weeds. In the following spring, it was mainly spread by tobacco aphids. Therefore, the disease is serious when there are more weeds in tobacco fields near cucumbers, tomatoes and other vegetable fields, high temperature and drought, and a large number of aphids. When too much nitrogen fertilizer is applied, the disease will be serious when the soil is barren, consolidated and sticky.

Control of tobacco mosaic disease

As tobacco mosaic virus is a mixed infection and spreads widely, it is necessary to strictly implement the plant protection policy of "prevention first and comprehensive control" for the prevention and control of tobacco mosaic virus, and do a good job in agricultural, chemical and other comprehensive control measures.

(1) Agricultural prevention and control measures:

1. Rational crop rotation and adhere to the tobacco-based farming system.

For the areas where tobacco mosaic disease occurs frequently, the tobacco field should be ploughed deeply during the winter fallow period, the tobacco stalk, weeds and other plant residues should be removed, the source of tobacco mosaic disease should be reduced as much as possible, and the tobacco mosaic disease should be distributed reasonably according to the actual situation. improve and optimize the ecological environment for tobacco growth, improve the industrialization level of tobacco production areas, and speed up the adjustment of planting structure in tobacco areas. If aphids parasitic Solanaceae or Cruciferae crops such as tomato and pepper are not planted near the tobacco field, the tobacco field should implement a rotation system of 1-2 years as far as possible, and wheat tobacco interplanting can also be properly carried out in the tobacco areas of northern China. Combined with soil improvement, planting green manure, orange stalk returning to the field, field health and other rotation can effectively control tobacco mosaic disease.

2. Planting resistant and tolerant varieties

This is an economical and effective way to control tobacco mosaic disease. Local varieties resistant to TMV disease such as Liaoyan 8, Liaoyan 10 and Liaoyan 12, Taiyan 5 and Taiyan 6, introduced such as Burley 21, Kirk 86, Liaoyan 15, Yanbian 9205, CV09-2 of Tobacco Research Institute of Chinese Academy of Agricultural Sciences, etc. The varieties resistant to CMV are TT6 and TT7 series flue-cured tobacco varieties. NC89, K326 and G140 all showed certain resistance. Transgenic NC89 homozygous lines with double resistance (resistance to CMV and TMV) have been obtained, and large-scale experiments showed good disease resistance.

3. Strengthen the management of seedbed and cultivate disease-free and strong seedlings.

First of all, we should pay attention to the selection of seedbeds, seedbeds should be as far away from vegetable fields, roasting rooms, air sheds and other places as far as possible. Secondly, bed soil and fertilizer should not be mixed with the residue of diseased plants, pay attention to remove weeds near the seedbed. Third, disinfect the nutrient soil of the seedling bed and eradicate the residual virus in the seedling bed soil. Before seeding, the seedbed was carefully sprayed with chlorpromazine, dimethazone and other agents to kill the virus and other germs in the bed soil and prevent the seedlings from being susceptible to disease. Fourth, cultivate disease-free and strong seedlings. When the tobacco seedlings were unearthed and pulled the cross, the seedlings were sprayed with nutrient solution to promote the development of tobacco seedlings root system, slow seedlings and strong disease resistance after transplanting. Fifth, strengthen the nursery bed management, strict non-toxic operation rules. Timely seedling, fixed seedling, reasonable fertilization and watering, effective temperature and humidity control. When operating, wash hands with soapy water, strictly prohibit smoking, and try your best to reduce the contact between operating tools, hands, clothes and tobacco plants.

4. Strengthen the management of field period and improve the disease resistance of tobacco to natural environment.

The tobacco field should turn the soil deeply before winter and rake the soil repeatedly and carefully so as to ripen the tillage layer and reduce the source of infection.

(2) Chemical control measures:

1. Apply more fertilizer to improve the disease resistance of the plant.

The organic fertilizer is applied reasonably according to the actual situation of the tobacco field. after the tobacco seedlings are planted, the special tobacco liquid of 1000 times "Xinxiu" or 1000 times of "Sea Magic" can be sprayed, and attention should be paid to topdressing, cultivating soil and watering in time, so as to promote the root system and growth of tobacco plants to develop and grow healthily. improve disease resistance.

2. Hygienic operation to reduce the spread of virus.

When operating in the field, wash hands with soapy water in advance, disinfect tools, and prohibit smoking. Topping and forking should be carried out after the rain and dew is dry, and pay attention to the topping and branching of diseased plants need to be carried out finally.

3. Pay attention to repelling aphids and preventing them from spreading virus.

Laying silver gray plastic film or hanging silver gray reflective film in seedling bed and tobacco field can effectively prevent aphids from migrating to tobacco field.

4. Chemical control.

① was sprayed to reduce the spread of aphids.

The aphids on nearby Solanaceae crops and weeds should be sprayed and killed before planting tobacco to avoid the spread of winged aphids. The yellow dish should be used to trap aphids within 40 days after planting tobacco. When winged aphids are found in the dish, the field can be sprayed immediately. In addition, the use of imidacloprid sustained-release granules when planting tobacco can effectively control the number of aphids in tobacco field and prevent the spread of virus diseases in the field.

② sprays antiviral drugs.

Virus inhibitors were sprayed at the seedling stage. Within 7-30 days after loading, virus inhibitors were sprayed 2-3 times with 600-fold solution and 250-fold solution, paying attention to the front and back of the leaves. 2-3 times should be applied to prevent aphids within one month after transplanting.

In a word, tobacco mosaic disease is transmitted through many ways, so the prevention and control of tobacco mosaic disease should be based on agricultural measures, combined with effective antiviral agents, and reasonable and hygienic agricultural operation. through the combination of agricultural measures and chemical measures to create environmental conditions conducive to the growth of tobacco leaves but not conducive to the occurrence and development of tobacco mosaic disease, and effectively control the harm of tobacco mosaic disease to tobacco leaves. Finally, improve the yield and quality of tobacco.

The pathogen of tobacco mosaic disease and its control strategy

It is understood that tobacco mosaic disease harms tobacco leaves. Tobacco mosaic disease will cause disease spots in tobacco plants and affect the normal growth of tobacco.

Generally speaking, tobacco mosaic disease is also called oil head. After tobacco plants are infected with tobacco mosaic disease, the veins of young leaves will show a translucent state. The mesophyll tissue on both sides of tobacco leaf veins will appear light green. Tobacco mosaic virus proliferates massively in leaves, which leads to the increase of tobacco mesophyll cells, and tobacco leaves will show a mosaic shape. With the spread of tobacco mosaic disease, dark brown necrotic spots appeared in a large area of tobacco leaves. In the case of tobacco mosaic disease is more serious, the leaves appear deformity and shrinkage. Tobacco plants with early diseases will be dwarfed and grow slowly, and tobacco can not blossom and bear fruit normally, which is easy to cause tobacco shedding. Mosaic disease also harms common strains, tomato strains, macular strains and pearl spots, resulting in symptom diversity due to differences in pathogenicity and co-infection with other viruses. The pathogen of tobacco mosaic disease is mainly transmitted through juices. The slight friction of the diseased leaves causes a micro-wound, and the virus can invade, not from the large wound and natural orifice. Tobacco mosaic virus infection can be aggravated by the application of immature organic fertilizer and cultivation of virus-carrying soil.

In order to control tobacco mosaic disease timely, effective measures should be taken to control tobacco mosaic disease. Agricultural personnel strengthen the management of tobacco, select tobacco varieties with strong disease resistance and high quality for sowing; deep ploughing and renovating the soil in tobacco planting areas is more conducive to the growth and development of tobacco in the later stage; after discovering diseased tobacco plants, agricultural personnel pull them out in time, take them away from the planting area for destruction, and spread quicklime in the diseased plant area, which can effectively control the spread of tobacco mosaic disease. Strengthen the management of tobacco seedling stage, select disease-free plants to harvest seeds, or soak the seeds with 0.1% silver nitrate or 0.1% rain 0.2% zinc sulfate and 0.1% trisodium phosphate solution for 10 minutes, and rinse the seeds repeatedly after soaking. In the early stage of tobacco mosaic disease, spraying 2% aminooligosaccharin 6000 times, or high tech 32% bromomorphine guanidine, or 1.5% Zhiyiling emulsion or 10% virus king wettable powder, Rib% Huayening wettable powder 300,500 times, can prevent and alleviate the effect of tobacco mosaic virus.