I. Prevention and treatment of tobacco virus diseases
The prevention and control of tobacco virus diseases should be based on "prevention". Take a series of disease prevention measures around this center, and this series of measures should be aimed at reducing virus infection or cutting off infection routes and improving the disease resistance of tobacco itself. The following are the main preventive measures.
1) Selection of disease-resistant varieties In terms of resistance to mosaic disease, the disease resistance of domestic bred varieties is much higher than that of imported varieties, which can be appropriately selected according to local specific conditions. However, most of these disease-resistant varieties have TMV resistance genes, which are often contradictory to quality traits. Therefore, attention should be paid to cultivation and control in specific application to improve the quality of tobacco leaves.
2) Cultivation and disease prevention
1, pay attention to seedbed and field hygiene.
1) seedbed disinfection, reduce the source of poison.
Disinfection of seedbed and seedbed soil can effectively reduce the amount of virus around the soil and seedbed. In the case of intensive seedling raising, this operation is easy to carry out and should be advocated. During disinfection, various agents with strong inhibitory effects on viruses can be used, such as 22% virus-specific, 1.5% plant disease-resistant spirit No.2, 2% ningnanmycin, virus spirit, bacterial toxin, etc.
Fumigation and disinfection have been adopted in Heilongjiang and other places, and the effect is very good.
2) seed disinfection
Although tobacco seeds are not toxic, the surface and impurities of the seeds will be toxic, so it is very necessary to disinfect the seeds. The disinfection method can be disinfected by the above agents, and can also be disinfected by copper sulfate and silver nitrate.
2. Cultivate healthy seedlings, cultivate disease-free healthy seedlings and improve the disease resistance of tobacco plants.
3. Balance nutrition and improve the disease resistance of tobacco plants.
Reasonable ratio of nitrogen, phosphorus and potassium and appropriate increase of potassium fertilizer dosage can improve the disease resistance of tobacco plants. It is advocated to spray potassium dihydrogen phosphate on leaves in the early growth stage. The increase of potassium content in tobacco plants can effectively improve the comprehensive disease resistance of tobacco plants, especially the disease resistance to mosaic and brown spot.
3) Avoid aphids and prevent diseases
1. Minimize aphids from entering seedbeds or tobacco seedlings.
1) When the forged seedlings are aired at seedling stage, the air inlet should be blocked with insect net to prevent aphids from entering. Or when forging seedlings, film is still put on the seedbed of seedlings to drive away aphids.
2) When raising seedlings and forging seedlings in greenhouse, a reflective film can be hung between the north wall and the seedling tray to drive away aphids.
2. Plastic film covering
Under the comprehensive action of rising ground temperature, plastic film mulching promoted the growth of tobacco plants and improved their disease resistance. At the same time, it can effectively repel aphids as a virus transmission medium, greatly reducing the harm of mosaic disease by about 50%.
3. Wheat and tobacco interplanting
During the growth period of wheat and tobacco, wheat can effectively block the transfer of aphids on various tobacco plants, thus reducing the chance of virus transmission, greatly reducing the occurrence of virus diseases and achieving good disease prevention effects. Wheat-tobacco interplanting can be used in some areas.
Iv) application of antiviral agents
The main function of antiviral agent is to inhibit the activity of virus and induce tobacco plants to produce resistance, so it is necessary to master its use method before the virus invades tobacco plants. According to the research results of antiviral resistance mechanism, the following application procedures are put forward: seedling stage 1 ~ 2 times, before transplanting 1 day/kloc-0 times to prevent the virus from spreading through contact; Apply it 2 ~ 3 times at the initial growth stage after transplantation. It is advocated to spray tobacco plants for protection before field operation.
At present, the antiviral agents used in production are: Jinyebao 400 times, Weiertai 800 times, ningnanmycin 200 times and Preventive Medicine (Ⅱ) EC 600 times.
V) Other auxiliary measures
1. Early-onset tobacco plants should be pulled out as soon as possible and taken out of the tobacco field for destruction to eliminate the source of reinfection.
2. Apply eccentric fertilizer. When there are common diseases in the field, apply quick-acting nitrogen fertilizer to the diseased tobacco plants to promote their stem cutting and slicing. You can also spray 1% urea. Note: Tobacco is particularly sensitive to urea, so the concentration should be strictly controlled when applying, and it is not allowed to increase at will.
Second, tobacco brown spot disease
1. Planting disease-resistant or disease-tolerant varieties Among the varieties currently promoted nationwide, Zhongyan 90, Zhongyan 9203, CF80 and K346 are relatively disease-resistant.
2, timely early planting, cultivate strong seedlings.
3. Appropriate sparse planting, control the amount of nitrogen fertilizer and increase the application of phosphorus and potassium fertilizer.
Spraying dipotassium hydrogen phosphate on the leaves of tobacco plants in the cluster stage, vigorous stage and flat stage can obviously reduce the harm of brown spot.
4, timely harvesting.
5. Use pesticides to control 40% Junzhujing 500 times, 10% Baolian 1000 times, every 7- 10 day/kloc-0 times, generally 2-3 times. The control effect can reach more than 70% at the initial stage of the disease, and other types of pesticides such as Xingnong 660B also have good control effect.
Third, tobacco black shank disease
1, planting resistant varieties K326, K346, K394, NC82, NC89, G 140, G28, G80, Zhongyan 90 and other varieties are more resistant to black shank disease.
2. Rotation is an effective preventive measure, because the main source of infection of black shank disease is diseased soil.
3. Plant early.
4. Ridges and plants to prevent water and water accumulation. Remove diseased leaves and diseased plants in time. 5. Spraying 25% metalaxyl 500 times solution on roots 1-2 times at the initial stage of the disease, the control effect reached over 80%. Other pesticides in metalaxyl series, such as antiviral alum and ethyl phosphate, also have good control effects.
Four, tobacco wildfire disease (including angular leaf spot)
1. Disease-resistant varieties: G80 and Jinxing 6004 showed certain disease resistance, and some burley tobacco and cigar varieties showed certain disease resistance.
2. Rotation for 3-5 years can effectively reduce the harm by destroying the diseased body in tobacco fields and reducing the source of infection.
3. Fertilize nitrogen, phosphorus and potassium reasonably, and increase the dosage of phosphate fertilizer and potassium fertilizer appropriately.
4, timely early planting, timely topping, early harvest.
5. Chemical control: 1: 1: 160 bordeaux solution is sprayed into 200 units/ml of agricultural streptomycin, and sprayed 2-3 times every 7- 10 days.
Five, tobacco bacterial wilt
1. The resistant varieties K326, K346, K394, G 140, G80, G28, NC82, NC89 and Jiao 176 all showed some resistance to bacterial wilt.
2. Crop rotation and Gramineae crop rotation for 3-5 years.
3. Strengthen field management and soil cultivation, dredge ditches and pay attention to drainage to avoid excessive soil moisture. Proper application of 0. 1% boron fertilizer sand can improve the disease resistance of tobacco plants.
4. Chemical control: At the initial stage of the disease, irrigate the roots with 200 units/ml of agricultural streptomycin (50 ml per plant).
Six, tobacco root-knot nematode disease
Promote comprehensive prevention and control with disease-resistant varieties as the mainstay, supplemented by cultivation and chemical control.
1. There are many kinds and physiological races of resistant root-knot nematodes, and varieties resistant to all kinds and physiological races have been changed in production. Meloidogyne incognita 1 is the most widely distributed race in China, and NC89, NC95, G28, G80, K346 and Zhongyan 14 can be selected.
2. Crop rotation and gramineous crops should be rotated for more than 3 years, and paddy-upland rotation is the best.
3. Apply sufficient base fertilizer to cultivate strong seedlings.
4. Chemical control:
Seedbed soil can be fumigated with methyl bromide. 2-3kg/mu of 5% aldicarb granules and 0.3-0.4kg/mu of 50% azinphos granules.
Seven, tobacco aphids
1, Prevention and control of aphids in early spring In order to avoid the harm of tobacco aphids to tobacco, we can combine the normal management of peach trees in early spring to prevent and control aphids on peach trees after the eggs hatch and before the leaves roll, so as to reduce the number of migratory aphids and reduce the sources of aphids in tobacco fields. 2. In the seedbed stage, silver film can be used to drive away aphids, so as to reduce asymptomatic tobacco seedlings during transplanting.
3. Pesticides can be used to control tobacco in the field growth period, and iron should be reached when transplanting. The dosage of iron for tobacco control is 15%,100-150g/mu, and 5% aldicarb is 500g/mu. When transplanting tobacco, apply it around the rhizosphere of tobacco plants, and the residual effect period is about 60 days. The combination is timely. In addition, chemical control can also be used in the rising stage of aphid population in the field. 40% omethoate EC 1000- 1500 times, 50% chlorpyrifos 3000-5000 times and 90% wanling powder 3000-4000 times can be used for spraying. When controlling pesticides, we must pay attention to the quality of pesticide application, spray evenly, and spray all the parasitic leaves of tobacco aphids to ensure the control effect.
4. Topping and sowing in time will worsen the food conditions of tobacco aphids and promote wingless aphids to move out of tobacco fields.
5. In areas with other measures, measures such as wheat-tobacco interplanting and silver film mulching can also be adopted to reduce the harm of tobacco aphids.
Eight, tobacco budworm
1. Killing pupae by ploughing in winter All over the world, tobacco budworms overwinter in soil as pupae. Timely winter tillage can achieve the purpose of mechanically killing pupae, exposing water loss, worsening the wintering environment and increasing the feeding opportunities of natural enemies.
2. Killing larvae Check the new leaves and tender leaves in the tobacco field at 4-9 am on cloudy or sunny days during the larval damage period. If there are fresh wormholes or dung, find out the larvae and kill them immediately.
3. Trapping adults Use poplar branches or sex pheromones to trap and kill adults. Setting method of sex attractant (lure core): Place a water tray with a diameter of 35 ~ 40 cm on a simple tripod, add a little washing powder to the water, and hang the lure core 2 ~ 3 cm above the water surface, and the trap is slightly higher than the tobacco plants. Adults are hung with bait for a long time, and the bait is valid for about 20 days, with 1 ~ 2 traps per mu.
Before 4.3 years old, the following chemicals can be selected for control: 25% carbaryl EC 500 ~ 1000 times, 90% wanling powder 3000 times, 2.5% mirex EC 2000 times and 50% phoxim EC 1000 times.
5. Pay attention to the protection of natural enemies in biological control, and give full play to the natural control role of natural enemies; If biological agents are used for control, such as B.T. preparation (containing 654.38 billion live spores per gram) and 654.38+0000 times solution, etc. When using biological agents for control, we must pay attention to the quality of application.