Symptoms Tobacco is a noncommunicable disease caused by the harmful substances in the air. It is called climatic spot disease or climatic spot disease. Seedling stage, adult stage can be disease. Young leaves and spreading leaves are heavily damaged, and the disease is regularly distributed. The tip, leaf base, and middle part of the leaf are relatively concentrated, and the tissue along both sides of the leaf vein expands. At the beginning of the lesion, the size of the water droplets on the tip of the needle is grayish or brown, and it can be expanded to a large round spot with a diameter of about 1 to 3mm. The necrosis occurs in the middle and is surrounded by chlorosis. In severe cases, multiple lesions fuse into large plaques. The lesions on both sides of the veins were irregularly shaped and scorch, with dead leaves and leaves. In the near-mature mid-lower or bottom lobe, the lesions were perforated, with many scattered fine round spots appearing on the leaf surface, about 5 mm in size, and later also perforated, but there was no dark-brown boundary on the edges of the lesion, different from the perforation. disease. In recent years, the disease has been widespread, especially in the south, causing serious harm. Pvc Glove,Disposable Vinyl Clear Gloves,Disposable Sterile Pvc Gloves,Disposable Transparent Sterile Pvc Gloves BIQIAO MEDICAL TECHNOLOGY(HENAN) CO.,LTD , https://www.medical-technology.net
Cause Tobacco is a crop that is sensitive to air pollution. With the development of industrial production, toxic substances in the air continue to emerge. The main cause of tobacco leaf spot disease is the presence of ozone (O3). When the ozone concentration reaches 0.03 to 0.05 mg/kg, it will have an adverse effect on chlorophyll-rich plant tissues such as tobacco, causing spotting on the tip of the leaf. , spots or spots, chloroplast damage, especially the palisade tissue is the most sensitive. Ozone is a strong oxidant. When it is manifested, it can stimulate the host to breathe while inhibiting photosynthesis. When the stomata are opened, ozone enters the air cavity through the stomata and can be poisonous. Followed by industrial waste gas such as carbon dioxide, nitrate, acetyl peroxide, ozonated ethylene-1 and other pollution. In addition to the direct contact with the tissues of the leaves, some of them convert to form ozone and cause damage. The degree of occurrence of climate patches often depends on the concentration and duration of ozone; the cultivation environment, especially humidity, nitrogen levels and planting density; the microclimate before, during and after ozone; the age and development stage of the leaf; tobacco Variety and other factors. In the production, there is a long period of low temperature, more rainy weather, and less sunshine. The reasons are as follows: First, during the reversal of temperature, high-level ozone can easily settle due to the anti-cyclone flow of air, resulting in an increase in ground-level ozone concentration; second, long leaf stomatal opening time, poor root development, resulting in insufficient nutrients; and third, planting in wet fields. Tobacco, soil nitrogen deficiency or excessive nitrogen fertilizer, phosphorus supply can not meet its normal physiological needs, it is easy to produce climate patch. In addition, planting too early, tobacco plants after 60 days of transplanting or the density is too large to be susceptible to disease, Fujian investigation found that the incidence of varietal differences, K-series, G-series susceptible.
Control methods (1) Breeding resistant varieties such as Zhongyan 90, Nc89, Nc628, Yunyan No.2 and so on. (2) Do not grow tobacco on the outskirts of the city or where there is industrial pollution or land. (3) Strengthen tobacco field management. From the cultivation of strong seedlings, after transplanting, low temperature and more rain should be timely cultivating, raising temperature and humidity, promoting the development of the root system, but also pay attention to prevent early drought; the use of formula fertilization technology to achieve a balanced supply of nitrogen, phosphorus, potassium, to prevent the planting Density, to avoid excessive shading of leaves; spray anti-oxidants on foliage when necessary. Such as trimethyl quinoline, N, N-diphenyl phenyl ethylene diamine and so on. (4) The incidence of dithiocarbamate can be reduced by spraying 65% zeocin WP or 70% mancozeb WP 500 times in the initial stage of disease. (5) It is necessary to pay attention to the timely spraying of Huayening II or 20% virus A WP 500 times, and 0.5% antiviral Feng (mushroom proteoglycan) water 300 times. (6) Spray Huimanfeng organic active liquid fertilizer 600-800 times.