Tobacco diseases in the field mainly include black shank, brown spot, bacterial wilt, angular leaf spot, black rot, wildfire, common mosaic, tattered leaf spot, cucumber mosaic, powdery mildew, root-knot nematode and climate spot. Pests mainly include cutworms, needle flies, crickets, aphids, tobacco worms, Bemisia tabaci, thrips, tobacco leaf miner, tobacco borers, snails, wild slugs and so on. For tobacco diseases and insect pests, we should adhere to prevention first, adopt comprehensive control methods, control the occurrence and development of diseases and insect pests, and ensure the quality and yield of tobacco leaves. Resistant varieties such as 1. burley tobacco, 40 1 strain and green stalk are susceptible to black shank disease, powdery mildew and tattered leaf spot, and k326 and g28 have strong resistance to these diseases. 2. Strengthen the cultivation management (1). Crops such as sugarcane or peanuts should be rotated for 2-3 years on dry sloping land; Tobacco-rice rotation is implemented in rice fields every year. (2) Avoid using compost that may contain patients, disabled people and eggs in seedbeds and fields. (3) Remove diseased leaves or plants in time and burn them centrally. (4) Cultivate healthy and disease-free seedlings and do a good job in field hygiene. After tobacco plants are harvested, they should be ploughed in time to burn the roots of tobacco plants. Deep ploughing kills pests in winter. (5) In tobacco-growing areas with serious pests and diseases, fumigants (such as methyl bromide) can be used for soil treatment. 3. Physical control can use light to trap and kill adult crickets, ground tigers, etc. Or use poplar branches to tie and hang on bamboo poles to trap, or use artificial killing methods to kill some pests. 4. Chemical control Using chemical agents to control tobacco diseases and insect pests is an important measure of comprehensive control. The commonly used pesticides for pest control are 40% dimethoate EC, 40% omethoate, 50% phoxim, 40% acephate, 20% metoclopramide and 25% fenvalerate. The main drugs to control tobacco diseases are 95% Dixon, 20% Kangkuling, streptomycin, dt, 10% fenamidophos and mancozeb. According to the experiment of Henan Agricultural University 1983, spraying O.14% zinc sulfate at the cluster, vigorous and mature stages of tobacco plants can reduce tobacco mosaic. Spraying 1 000 times of Ling Jun solution and 1000 times of NS-83 resistance enhancer solution for 2-3 times, once every 7-65,438+00 days, also has a significant effect on tobacco mosaic. The key to tobacco mosaic lies in the control technology. Tobacco disease is an important disease that leads to the reduction of tobacco production and quality. There are 1 1 species in China, 7 species are common and 3 species are the most important. The symptoms, pathogenesis and comprehensive control techniques of common tobacco virus diseases are introduced as follows: 1. Symptom identification and pathogenesis 1. Tobacco mosaic. Both seedlings and adult plants can be damaged, and the veins of seedling leaves turn pale green, showing translucent "bright veins", and after a few days, yellow-green "flowers and leaves" are formed. After the disease of tobacco plants in the field, the phenomenon of "bright veins" first appeared on the heart leaves, followed by mosaic, blister, deformity, leaf shrinkage and distortion, leaf curl and drooping or tip narrowing. The virus (tmv) spreads through contact and friction, and the seeds, fertilizers, soil and other hosts mixed with sick and disabled people, and even roasted tobacco leaves and powder can become the primary source of infection. Sick tobacco seedlings are an important source of field diseases. In the field, the virus spreads through the contact between sick plants and healthy plants, as well as the contact between people's hands, clothes, farm tools and tobacco plants when working in tobacco fields. 2. Tobacco and cucumber yellow leaf disease. At the early stage of the disease, the leaves showed "bright pulse" and&; The symptoms of ldq uo's "flower heart" are: in severe cases, the upper leaves are narrowed, the leaf edges are rolled up and twisted, the plants are dwarfed, and brown "lightning-like" necrotic markings are formed on both sides of the lateral veins of the middle and lower leaves. The disease (cmv) mainly overwinters on vegetables, perennial trees and farmland weeds, and is spread by aphids, human farming operations and mechanical contact. The virus is mainly transmitted by aphids. 3. Tobacco potato virus disease. There are many diseases in the field during the adult stage, including systemic infection and whole plant diseases, which are characterized by dark brown necrosis of leaves, veins and stems. The disease (puy) overwinters on potato tubers and solanaceae crops (tomatoes, peppers, etc.). ) and perennial weeds planted in the greenhouse that year. 4. Tobacco etching virus disease. It mainly occurs in the field period, and the lesion first fades into small yellow spots, which can be covered by leaves in severe cases, and then spreads into brown-white linear erosion spots along the veins. The virus (tev) overwinters on vegetables and weeds in the field, and spreads through aphids and frictional contact. 5. Tobacco ringspot virus disease. Annular necrotic spots or curved wavy line spots with a diameter of 4 ~ 6 mm are produced on the leaves, and the plants are dwarfed, and the leaves become smaller, with little or no fruit. The virus (trsv) overwinters on tobacco, soybean and various weeds, and is spread by aphids, nematodes, thrips and farm tools. 6. Tobacco beet curl top virus disease. During the field period, the diseased plants were severely dwarfed, the internodes were shortened, the leaves were shriveled, the leaf edges rolled outward, the mesophyll was bubbly, the leaves were dark green, the terminal buds were stiff, and then they gradually died. The virus (bctv) overwinters on perennial host plants, and is mainly transmitted by field leafhoppers. 7. Horse potato X virus disease. It mainly occurs in the adult stage, showing symptoms such as bright veins, mild mosaic or chlorosis mottle, ring spots and necrotic stripes. Virus (pvx) overwinters on potato tubers and other hosts, and spreads through mouthparts chewing insects or juices such as locusts and grasshoppers. Aphids and seeds are not contagious. The above virus diseases can occur compound infection on the same tobacco plant, which aggravates the disease. In the field identification, we can judge by the above symptoms, and the preventive measures are mainly to cut off the source of the virus. 2. Control technology 1. Rational rotation. Rotation with Gramineae crops for 2 ~ 3 years, away from solanaceae crops cultivated in greenhouses, greenhouses and open fields to prevent virus transmission. 2. Plant disease-resistant varieties. According to the layout requirements of local tobacco companies, plant the varieties they recommend, because the varieties they choose meet the dual requirements of industrial processing and disease resistance. 3. Cultivate healthy and disease-free seedlings. The field soil where tobacco and solanaceae crops have not been planted for more than 2 years is selected as the seedbed, organic fertilizer polluted by tmv is not applied, and the seeds are soaked in 0. 1% trisodium phosphate solution for 0/0 minute to inactivate the virus, and then germinate and sow. Seedbed covered with plastic arch shed, scientific management. Nurses are not allowed to smoke during the operation to prevent the virus from polluting the seedbed and ensure the health of seedlings. Before transplanting, spray 1 ~ 2 times with 200-260 times of 2% Junkeduoke (ningnanmycin) solution to prevent diseases. The medicine has that effect of destroying virus particle and improving the antiviral ability of tobacco seedlings. 4. Choose healthy seedlings for transplanting and strictly eliminate diseased seedlings. When planting tobacco, only healthy seedlings without any symptoms are selected, and the eliminated diseased seedlings are buried deep and destroyed to prevent the diseased seedlings from entering the field. After the seedlings survive, weed in the field in time to prevent the overwintering virus from infecting the tobacco seedlings. The diseased seedlings with symptoms should be pulled out and replanted in combination to ensure that there are no diseased seedlings in the field. Operators should wash their hands with soapy water in advance, do not smoke during the operation, and do not walk around and touch the tobacco seedlings repeatedly in the field to prevent people from spreading poisons. When sowing seedlings, we should plant them at a reasonable density, apply sufficient fertilizer and water to ensure survival and improve plant disease resistance. 5. Spray medicine in time to prevent field diseases. The first application started on 15 days after seedling planting. Spraying tobacco seedlings with 200-260 times of 2% aqueous solution of Junkeduoke, spraying every 10- 15 days, with 40-50 liters of liquid medicine per mu each time. If there is a tobacco aphid in the field, it can be mixed with insecticides such as pirimicarb and imidacloprid for 2 ~ 3 times in a row. In order to supplement foliar fertilizer, drugs can also be mixed with foliar fertilizer according to their respective concentrations. When foliar fertilizer is used alone, 0. 1% sodium alginate is better, which can promote growth and prevent diseases.
Satisfied, please adopt.