Tobacco is a economic crop with high economic value. The development of tobacco production can not only provide raw materials for the cigarette industry, meet people's preferences, increase farmers' income, and earn foreign exchange through exports, but also extract nicotine from tobacco for agricultural pesticides and medicine; it can also refine malic acid and citric acid. , Used in the confectionery and food industry; tobacco seed oil 30-40%, can do paint and soap raw materials; tobacco stems can be made of fiberboard, activated carbon and charcoal oil and so on. Therefore, tobacco and everyone's life are closely related, in order to improve the quality and yield of tobacco, tobacco disease prevention and control is also an important part of the tobacco growing process. This article mainly discusses the prevention and control of tobacco wildfire disease. First, the symptoms Wildfire disease mainly damages the leaves and can also invade flowers, pods and seeds. Symptoms of the leaves started with water-stained, round, discolored spots. Later, the spots expanded, the center became brown, and there was a wide circle of yellow-green halos around it, which was most evident at the seedling stage or when the climate was humid, and its diameter could reach 1 - 2 cm. The lesions merged into irregular large spots with ring veins. When the weather is wet, there is a thin layer of pus on the surface of the diseased part. After drying, the brown part of the lesion is crumbling and the perforation falls off. In the case of rain, humidity and seedlings, the disease spread rapidly, often causing the seedlings to rot and fall to death, such as being burned by wildfires. After the onset of stems, pods, and sepals, irregular spots were found on the top of the stems, and water-stained lesions appeared at the beginning. After that, they turned brown and died. The lesions on the stems were slightly subsided, and the yellow halo was not as pronounced on the leaves. Second, the pathogen Wild fire fungus is short-bar-shaped, non-deciduous, does not produce internal cells, Gram-negative, size is 0.5-0.75x1.5-2.5 microns, 1-6 unipolar flagella, about 4-5 microns in length; The off-white round colonies produced on the medium had fluorescent substances; the typical colonies on the beef juice medium were initially clear, mixed white, slightly raised, and transparent on the edges. The center is opaque. The colonies are uniform and free of particles, with a dark yellow center. The aerobic character of the pathogen is optimum, the optimum development temperature is 29-30°C, the highest is 32-34°C, the lowest is 0-2°C, and the lethal temperature is 49-50°C for 10 minutes. It can only survive for 12 days on potato agar medium, but it can live on beef juice medium for 300 days (room temperature), and it can survive for 0.5-3 years at 5°C, on sterile water and pure agar. Can live 0.5-3 years. Can produce wild fire toxins: a special kind of amino acid, can disturb the metabolism of methionine, yellow halo around the lesion is caused by the destruction of the structure of chlorophyll. Third, the disease cycle The primary sources of infection in this disease were mainly water-fertilizer and manure, contaminated seeds, inside and outside of seed coat, and embryo-borne bacteria that were contaminated by sick and sick bodies in the winter. The disease dies quickly after the diseased tissue rots and decomposes, and in dry diseased tissue it can survive for 6 years; the re-infestation of the bacteria is mainly due to wind and rain or insects spreading from the wound or natural orifice. When invading from the stomata, the surface of the blade must be moistened and the pores filled with water to successfully complete the infection. The overflow of the diseased part needs rain to spread before it can be seen within 3-5 days after the invasion. IV. Transmission routes and conditions Diseases and bacteria seeds are the main wintering sites for wild fire bacteria. The incidence of continuous cropping is more severe than that of crop rotation. The longer the duration of continuous cropping of tobacco, the heavier the incidence. Germs that survive in the field weeds and grassroots crops can also cause initial infestation. In the field, germs are spread by rain or dew, and invaded by leaf stomata or wounds. In the optimum temperature conditions, especially in high humidity conditions and temperatures of 29-30 °C, the most beneficial disease; if the weather is dry, the disease is inhibited. Rainwater is abundant, rainfall is heavy, and especially storms often lead to the occurrence of tobacco wildfires. The storms are not only conducive to the spread of bacteria, but also cause wounds on plants and induce pathogens to invade; therefore, China Agriculture Network recommends that tobacco is often caused after heavy winds and rains. Serious disease of the plant. In addition to the pathogenicity and weather conditions, the incidence of disease depends to a large extent on the host's disease resistance and cultivation conditions. In general, there are too many nitrogen fertilizers in the field, lack of potassium fertilizer, young leaves, late-maturing glutinous rice, and excessively high-yield tobacco plants in the late growth stage. In tobacco fields where more fertilization is applied, if the plants are towed too early or too low, they will also cause serious disease. V. Prevention measures Tobacco wildfire disease prevention and control should be based on the "prevention-based, comprehensive prevention and control" plant protection policy, from the eradication of bacteria source and seedbed cleaning, combined with cultivation measures to promote robust growth of tobacco, take a variety of measures to prevent and treat it as soon as possible. Specifically, the following types of control technologies and measures can be used: (1) Selection of disease-resistant varieties, localities should choose to plant disease-resistant varieties according to local conditions, such as? Flue-cured tobacco varieties can be selected G80, Guanghuang 55, etc.; burley tobacco can choose white ribs 21, Kyl2, Kyl4, Kyl65, Kyl70, TY5 and so on. (2) Implement a reasonable rotation system for 3-5 years. Do not work with Solanaceae, Leguminosae, and Cruciferous crops; Crops should be ploughed and ploughed after tobacco is harvested. Diseased tobacco stalks should be treated before the winter. complete. (3) Reasonable fertilization and irrigation, no partial nitrogen fertilizer, pay attention to the combination of nitrogen, phosphorus, and potassium, apply special soil testing formula fertilizer for tobacco; do not apply tobacco disease residue body manure. Suitable early planting should be based on the soil fertility of the tobacco field, fertilization and plant growth conditions, timely and appropriate topping, so as not to overly dense plant growth, reduce disease resistance; early harvest, timely cleaning after harvesting the pasture and deep land. (4) Use disease-free seeds or sterilize seeds. Before brooding, use 1% copper sulfate solution or 0.1% silver nitrate solution to disinfect for 10 minutes or agricultural streptomycin 200ug/ml to soak seeds for 30 minutes to kill germs. Rinse after clean water and sow germination; strengthen cultivation and management after cultivating, and cultivate strong seedlings. Early planting; strengthen management after Dingmiao, pay attention to hardening the seedlings to control the occurrence of disease. (5) Chemical control: When the onset of the seedbed, the diseased leaves should be removed in time and sprayed with 1:1:160 Bordeaux mixture. Before transplanting, spray 200ug/ml of agricultural streptomycin or neomycin. When the first onset of disease in Daejeon, the diseased leaves were removed timely and chemically controlled. Early detection of a small number of diseased leaves should be carried out as early as possible or early harvesting to prevent spread; in the stage of onset of spotting, agents should be sprayed and 200 mg/kg of neemtophycin 150-200 mg/kg can be sprayed. Or 72% of agricultural streptomycin soluble powder 4000 times, or 30% copper oxychloride suspension 500 times; or use 30% DT 500 times, or 47% Garenon 600- 800 times liquid, or 77% can kill WP 500 times liquid and other agents, spray once every 7-10 days, continuous control 3-5 times. Or can spray 5% Garnett dust, or 5% antibacterial dust, or 5% DDT dust control. China Extract Powder For Use As Dietary Supplement Extract Powder, Extract Powder Manufacturer Shaanxi Kang New Pharmaceutical co., Ltd. , https://www.apipepdites.com
How to prevent tobacco wildfire