Difference Between Tobacco Target Spot Disease and Red Star Disease

There are obvious differences between tobacco target spot disease and red star disease in terms of onset period, disease site, disease rate, tobacco plant nutrition, disease spot color, disease spot ring pattern and tissue thickness.

1.Onset period: Target spot disease can occur in tobacco seedling stage or vigorous stage and roasting stage, while red star disease mostly occurs in mature leaves.

2.Occurrence site: Target spot disease mainly occurs on leaves, while red star disease can occur in the roots, stems and leaves of tobacco plants.

3.Incidence rate: Target spot disease has a rapid onset and rapid expansion, whereas red star disease has a slower expansion.

4.Tobacco plant nutrition: In tobacco fields with excess nitrogen, red star disease tends to be more severe, while target spot disease is more likely to occur in tobacco fields with low nitrogen fertilizer levels.

5.Lesion color: The lesions of red star disease are dark and mostly brown, while the lesions of target spot disease are light and yellowish-brown.

6.Lesion ring pattern: There is a gray mold layer in the middle of the lesion of red star disease, which is not easy to fall off, while the lesion of target spot disease does not have this characteristic.

7.Tissue thickness: Tissue necrosis is relatively mild, whereas target spot disease usually causes greater tissue necrosis.

In summary, there are significant differences between tobacco target spot disease and red star disease in many aspects, and it is necessary to prevent and treat them according to specific diseases.

Tobacco target spot disease: This disease can occur throughout the growth period, there will be water-soaked small round spots, when the age is too fast, and slowly form small round holes in the later stage, like bullet holes, so we also call them tobacco target spot disease. He was caused by the fungus.

This bacterium can harm tomatoes, tobacco, etc. Method:

36% thiophanate-methyl suspension is a very good broad-spectrum low-toxicity fungicide, which has a very good effect on tobacco target spot disease, and also has the effect of prevention and prevention. In addition, sclerotinia net, Bordeaux liquid, etc.

Ensure good ventilation and reduce humidity, this pathogen can remain on the residual leaves for overwintering, so when harvesting the residual leaves in the field are cleaned up in time.

Proper management: mainly including the implementation of water and fertilizer, the management of planting density, the humidity of the field, etc., seedbeds and greenhouses can not use flood irrigation.

It is also known as erythema, tiger eye, fire bubble spot, and spot disease. It can infect leaves, stems, peduncles and capsules. Leaf infection mostly occurs from the lower leaves and gradually develops upward.

The lesions are small yellow-brown spots at first, and then develop into brown round or near-round spots with russet or dark brown concentric rings. When the expansion is fast, a yellow halo appears around the edges. When humidity is high, dark brown or black mold can be seen on the spots.

The lesions are brittle and easy to break. In severe cases, the lesions fuse and cause the leaves to become crushed. Leaf veins, peduncles, capsules, stems are oblong or fusiform dark brown depressed spots.

Alter Aria alternata (fries)Keissler is called Alternaria and is a fungus of the subphylum Semi-Knowitives. The mycelium is septated and colorless. The conidia are apical curved, with 1-3 spacers, brown.

The conidia are brown, chain-borne on the peduncle, large at the base, small at the apex, inverted club-shaped or oval, mostly beaked, with 1-3 mediastinal septums and 3-7 transverse septums. The bacterium grows quickly and can produce toxins. It has also been reported to cause red star disease.

Tobacco red star disease is commonly known as "red spot" in Shandong, "spot disease" in Henan, Anhui and Liaoning, "hate tiger's eye" in Yunnan, and "artillery spot" in Guizhou, which is one of the main diseases in tobacco production in China. The disease occurs in all tobacco-producing areas in China, and it is serious in Shandong, Henan, Anhui, Heilongjiang, Jilin and other places; It is followed by Sichuan, Yunnan, Guizhou, Liaoning, Shaanxi and other tobacco areas. In addition, the spice tobacco production areas in Guangdong and the red tobacco production areas in Zhejiang are also more harmful.

The red star pathogen mainly overwinters on the residues of diseased plants such as tobacco leaves or weeds left in the field by hyphae. Conidia on diseased remnants can also overwinter directly, as a primary infection**. (1) Most provinces in China have changed to plant spring tobacco, so that it can ripen early, pick and roast early, and basically finish roasting by mid-August, so that tobacco can effectively avoid the warm and rainy season and greatly reduce losses.

Yunnan mostly sows seeds in the rainy season, and if it can be sown in early spring, it can avoid the peak of red star disease and reduce economic losses.

2) Reasonable dense planting The planting density is too large and the light is insufficient, and the leaves shade each other, which is conducive to the reproduction of pathogenic bacteria and leads to serious diseases. Therefore, according to the characteristics of the variety and soil fertility conditions, it is necessary to make reasonable dense planting, and the density is appropriate to the leaves without sealing the ridge at the adult stage, generally about 1200 plants.

3) Reasonable fertilization The use of nitrogen fertilizer in tobacco fields should not be too much and too late, so as not to cause late maturity, and phosphorus and potassium fertilizers should be appropriately increased. The ratio of nitrogen, phosphorus, and potassium is 1:1-2:

3 is advisable, or on the basis of nitrogen, phosphorus and potassium 1:1:1, spraying 1% potassium dihydrogen phosphate three times in the cluster stage, prosperous long period and flat top stage is also better.

Leave the leaves reasonably, and avoid the appearance of large and small leaves on the tobacco plant.

4) Do a good job of field sanitation and harvest or remove the bottom leaves in time. Do not litter the foot leaves, tobacco sticks and tobacco sticks that have been knocked off, but take them out of the field to be buried deep or dried and destroyed to reduce the source of infection.

5) Implement crop rotation Implement crop rotation, do a good job in field hygiene, and reduce the source of infection. Continuous cropping can increase the bacterial content in the soil, while crop rotation can reduce the bacterial content in the soil and reduce the damage of red star disease.