What treatments work best to control tobacco mosaic virus in flue-cured tobacco

For tobacco mosaic virus in flue-cured tobacco, before symptoms appear, spray antiviral agents such as Duxiao at 600-700 times dilution, Dongwang Shadu at 500 times dilution, Bingdute at 500 times dilution, or Bingdubike II at 500 times dilution. You can also spray 22% Jinyebao wettable powder at 400 times dilution, or 1.5% Bingduling emulsifiable concentrate at 500 times dilution plus 250 g of zinc sulfate and other agents. In addition, you should also know the symptoms and control methods of tobacco mosaic virus in flue-cured tobacco.

Symptoms and control methods of tobacco mosaic virus in flue-cured tobacco

(1) Symptoms of tobacco mosaic virus in flue-cured tobacco

1. The color of the leaf veins and adjacent mesophyll tissue becomes lighter. It appears semi-transparent. When held up to the light, the large and small veins of the diseased leaf are clearly visible, starting from the base of the leaf and spreading toward the tip, gradually spreading to the entire leaf. After a few days, the leaf color becomes uneven in shade, forming a yellow-green “mottled or mosaic symptom”.

2. When the disease is severe, the leaf becomes uneven in thickness. Blister-like patches form, the leaf margin gradually develops notches and curls downward, shrivels and twists, and some leaves even become thin and strap-like. Various deformities appear.

3. Plants infected early are stunted, with shortened internodes, do not tiller, and grow extremely slowly; the leaves do not unfold. Most can flower and set fruit normally, but the fruit and seeds develop poorly.

(2) Control methods for tobacco mosaic virus in flue-cured tobacco

1. Apply 10-15 kg of urea per mu diluted in water, breaking the plastic film and pouring it at the roots. This is because once mosaic virus occurs, the tobacco plant's root system does not develop; however, pay attention to the soil fertility of the plot and control the amount used, as a large amount will make the tobacco leaves difficult to yellow properly, which is not conducive to harvesting and curing.

2. Spray with Bingdubike at 600 times dilution + agricultural streptomycin at 1000 times dilution, then spray with Duxiao at 600 times dilution, and finally spray with Linnanmycin at 1000 times dilution. The interval must not be too long; all steps must be completed within 2 hours; repeat once after 5-7 days. Generally, two rounds are sufficient.

3. Seedbeds should be far from villages, curing barns, vegetable gardens and other sources of the virus. The water source must be clean and must not be contaminated by diseased plant debris. Seedlings should be raised in a centralized, unified, commercialized manner.

4. Maintain good field sanitation to prevent human-mediated transmission of the disease. Before the first cultivation, promptly remove already infected tobacco plants and weeds from the tobacco field, and do not repeatedly move between and touch diseased plants and healthy plants.

The most suitable temperature for the onset of mosaic virus is 28-30°C. Sudden dry hot winds or cold rain can both trigger the occurrence of this disease, so prevention must be done well beforehand.