Tobacco mosaic disease
Symptoms commonly known as smoke, crazy cigarettes, blue and white, oil head. After infection of tobacco plants, the lateral veins and branch veins of the young leaves were translucent, namely Mingmai. Leaf tissue on both sides of the veins gradually pale green. The virus in the leaf tissue proliferation, so that some of the mesophyll cells increase or increase, there is uneven thickness of the leaves, the color yellow and green, was a flower-like. After the degree of mosaic mottled, and now has a large area of ​​dark brown necrotic spots, particularly in the middle and lower old leaves, heavy leaves of disease shrinkage, deformity, distortion. The early-onset plants are shortened internodes, severely dwarfed, and grow slowly, failing to bloom and fruit. And easy to fall off. The shades that can develop are small and shrunken, the seeds are small and small, and they can't germinate.
The pathogen Tobacco Mosaic virus called tobacco mosaic virus, abbreviated as TMV, is a virus. Viral body rods, size 30018 (nm). Passivation temperature of 90 to 93 ° C for 10 minutes, dilution limit 1000000 times, 72-96 hours in vitro toxic period. The pathogenicity under aseptic conditions reaches several years and survives more than 30 years in dry disease tissues. There are different strains of the virus. There are four strains in China: common strains, tomato strains, macular strains and bead spots. The diversity of symptoms is caused by differences in pathogenicity and co-infection with other viruses.
Transmission routes and conditions TMV can overwinter on a variety of plants. The primary infestation source is the diseased residue and other host plants. In addition, the incompetent fertilized fertilizer may also cause initial infestation. It is mainly transmitted through sap. Slightly rubbing the sick leaves to create micro-wounds, the virus can invade, not invasive from large wounds and natural orifices. After invading, they propagate in parenchyma cells and then enter the vascular tissue to infect whole plants. At 22-28 °C, diseased plants began to show symptoms after 7-14 days. The field is re-infected by rubbing the diseased seedlings with healthy seedlings or agricultural operations. In addition, insects such as mites in the tobacco field and chewing mouthparts of tobacco insects can also spread the TMV virus. The suitable temperature for the occurrence of TMV is 25-27°C. The invasion is inhibited above 38-40°C, and the disease disappears above 27°C or below 10°C. Tobacco mosaic disease mainly occurs from the seedbed stage to the budding stage in Daejeon. Temperature and light greatly affect the spread of disease and epidemic speed, and high temperature and light can shorten the incubation period. Continuous cropping or interplanting with the Solanaceae crop increased the number of sources of poisoning, and the incidence and incidence of disease increased significantly. Unsanitary cultivation is an important cause of the epidemic. Touching between diseased and healthy plants, application of unripe organic fertilizers, and cultivation of soil with viruses can aggravate virus infection. Soil compaction, dry climate, field nematode damage heavier land mass.
Control methods (1) Select resistant varieties, fast development, resistant varieties adapted to local conditions such as Liao 44, 6315, Guanghuang 54, 176, Nc89, G80, 8611, etc., pay attention to the breeding of high-resistance varieties. (2) Strengthen seedling management. Seedbeds should use plots that have not been planted with tobacco and solanaceous plants and are far away from vegetable fields for more than 2 years. The use of TMV-contaminated manure is prohibited. The seeds collected from the disease-free, disease-free plants were selected or soaked for 10 minutes with 0.1% silver nitrate or 0.1% 0.2% zinc sulfate and 0.1% trisodium phosphate solution to remove the seed surface. The virus should be washed repeatedly after soaking. Before the seedlings and Dingmiao, wash the hands with soap and manage the seedlings first and then remove the diseased plants in time. (3) To implement crop rotation, do not interrogate or interplant with the Solanaceae plants, and it is advisable to work with grass crops for 2-3 years. (4) Strengthen the management of field questions, and it is strictly forbidden to move the infected seedlings into the field. Should be the first strain after the disease strains of the order of management, the operation should not be smoking, should not walk in the tobacco field, touch. Full application of nitrogen, phosphorus and potassium fertilizers, timely spraying of trace elements fertilizers, improve plant disease resistance. After transplanting, the seedlings will be properly cultivated, and the critical mass of water will be poured at the end of the mass to promote plant growth. When mosaic disease occurs, it is necessary to chase the quick-acting fertilizer in time, water the soil, promote the opening of the straw, and reduce the disease. (5) At the beginning of the disease, 1.5% of the diseased disease emulsion was used for lo00 times or 10% of the virus WP for 600 times (Qiqihar City Siyou Chemical Industry Co., Ltd.), and the cost of the ribs % Huaye Ning WP was 500 to 500 times. Liquid spraying can play a role in preventing and alleviating the virus. It has been reported that spraying with 0.1% sodium alginate also has a certain effect. In addition, 2% Ningnanmycin can also be used, with an active ingredient of 90 to 120g/ha, and the drug should be stopped before harvesting for 14 days.
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