Tomato bacterial wilt symptoms
The symptoms of the damaged seedlings in the seedling stage are not obvious. After the plants are flowering, the diseased plants begin to show harmful symptoms. The color of the leaves is light and wilting. The leaf wilting begins with the upper leaves. The initial leaves of the disease are wilting at noon, and return to normal in the evening and morning. Repeatedly, the wilting is intensified and finally died, but the plants are still cyan. The middle and lower cortex of the diseased stem are rough, and the adventitious roots and adventitious buds often grow. The stems of the diseased stems become dark brown, but the roots of the diseased plants are normal.
Causes of tomato bacterial wilt
The disease is caused by the infection of Pseudomonas aeruginosa Pseudomanassolanacearum. Harmful to tomatoes, eggplant, pepper, potato, ginger and other crops. The pathogenic bacteria mainly overwinter with the diseased body on the field soil. When there is no host, the pathogen can survive in the soil for 14 months, becoming the main source of initial infection of the disease. The bacteria are mainly spread by rainwater, irrigation water and agricultural implements, and the diseased potato pieces and the fertilizers can also carry bacteria. The pathogen invades from the root or stem base wound and spreads in the vascular bundle tissue in the plant, causing catheter blockage and cell poisoning.
The pathogens prefer high temperature, high humidity and acidic environment. The most suitable climatic conditions are temperature 30-37 Â° C, and the optimum pH is 6.6. When the soil water content exceeds 25%, the plant grows poorly, and it is heavy after a long rain or heavy rain. The main epidemic period in Zhejiang and the middle and lower reaches of the Yangtze River is from June to October. The susceptible period of tomato is the middle and late stage of tomato.
Perennial continuous cropping, poor drainage, poor ventilation, soil acidity, lack of calcium and phosphorus, extensive management, and high humidity in the field are relatively serious. During the year, the rainy season is heavy, and the summer and autumn are hot and rainy.
Tomato bacterial wilt prevention
1. For the seed treatment, the resistant varieties with bacterial wilt are selected, and the disease-free seeds are selected. Seed disinfection can be dry heat treatment at 70-73 Â° C for 3-4 days, or warm soup at 53-55 Â° C for 20-30 minutes, or impregnated with a concentration of 7000 mg / kg of neutral calcium hypochlorite solution 60 Minute, or soak the seeds in 10% trisodium phosphate solution for 15-20 minutes, rinse off, rinse with water, germination and sow.
2. Carrying out rotations For the successively affected plots, it is possible to stop planting tomatoes for more than 4 years in a certain area, and to rotate with cruciferous or gramineous crops for more than 4 years. At the same time of rotation, it is necessary to ensure that the source of irrigation water in the area and the line along the line have no bacterial wilt, and there is no pathogen in the water.
3. Seedbed disinfection Choose high dry and disease-free ground for seedbed, choose disease-free breeding. It can also be used to disinfect the seedbed with 50% of formaldehyde and 50 times of water, apply it to the seedbed at 20-40 liters/square meter, cover it for 3 days, then ventilate and dry for 2 weeks to completely volatilize formaldehyde. Ready to use. It is best to breed winter seedlings, soak and cultivate seedlings in a timely manner. When transplanting, the seedlings should have more soil and less roots.
4. When the soil is disinfected and transplanted, the streptomycin aqueous solution is used for the irrigation of the roots, 1 gram of 72% streptomycin sulfate soluble powder plus 15 liters of water, and 80 transplanted seedlings. However, the cultivation of large areas of soil for soil disinfection is costly.
5. Ecological control For facility cultivation, temperature and humidity management should be strengthened. During the emergence period, the temperature is kept at 22-25 Â°C during the day and 15-18 Â°C during the night. When the seedlings are transplanted, the high temperature can be ventilated and cooled. During the daytime, the temperature can be gradually changed from 25 Â°C to 18 Â°C to 12 Â°C, and 12 Â°C at night, which is conducive to the cultivation of strong seedlings. When the greenhouse humidity exceeds 70%, pay attention to ventilation and cooling. At the same time, according to different weather conditions, the opaque material can be exposed early and the greenhouse illumination can be adjusted, which is beneficial to the control of temperature and humidity.
6. Strengthen management Choose tomatoes rich in organic matter, deep soil layer or sandy loam soil to avoid planting in the soil with heavy texture. The soil with heavy texture is wet and dry, and the roots are severely damaged, which is easy to cause infection. For acidic soil, 100 kg of quicklime is applied per acre during the hoeing. After planting, a lime is placed around the base of the seedling to adjust the soil pH to above 7. Rational application of nitrogen fertilizer, application of potassium fertilizer, application of fully decomposed organic fertilizer or plant ash, or "5406" No. 3 strain 500 times liquid, if necessary, 10 mg / kg of boric acid solution for root dressing, can promote the growth of host vascular bundle, Improve disease resistance. It is cultivated with sorghum or cultivated with mulch and covered with mulch to keep the soil moisture uniform and loose and breathable. Strengthening drainage to avoid flooding of large water, flooding of large water not only causes disease, but also causes the humidity in the shed to rise, which is easy to cause other diseases and aggravate the occurrence of diseases. At the same time, it is necessary to avoid pouring large water when the soil is too dry. The cultivating and cultivating soil should be carried out in advance until the roots of the seedlings have not been stretched. After entering the flowering stage, the roots should not be cultivated and cultivated as much as possible to avoid root damage and prevent the bacteria from invading from the wound. In the field, the diseased plants should be removed and burned in time, and then 20% of the quicklime or 2% formaldehyde solution should be disinfected in the diseased cavity. Tools and other items used to treat diseased plants must be soaked in soapy water.
7. Grafting and disease prevention In severely ill areas, it is recommended to use citrus, wild tomato, rootstock No. 1 as rootstocks, and grafting and cultivating by splicing or docking. It is an effective measure for controlling tomato bacterial wilt in production.
8. Chemical agents for pest control Because the disease is often caused by underground pests, such as larvae of the armor-like insects and some nematodes, the roots of the vegetables cause many small wounds, which cause the bacterial wilt bacteria to sneak into the forest, thereby inducing bacterial wilt. Therefore, roots should be filled with 50% phoxim emulsifiable concentrate 500 times (or other insecticide). Use once every 5-7 days, continuously for 2-3 times.
9. Chemicals to prevent disease
Immersion root: When planting, use the bacterial wilt antagonist MA-7, NOE-104 to carry out large seedling root immersion.
Spray: Before the onset, you can use 25% succinated copper WP WP 500-600 times, or 70% succinyl phosphine aluminum WP 500-600 times, 80% chlorothalonil WP 600 times Liquid, 77% copper hydroxide wettable powder 800 times liquid, 72% streptomycin sulfate soluble powder 4000 times liquid, 47% spring Lei Â· Wang copper wettable powder 1000 times liquid spray, spray once every 7-10 days, continuous Spray 3-4 times. Tomatoes that did not develop disease were also sprayed with the above agents for protective spraying.
Irrigation root: In the early stage of the disease, you can use 3% zhongshengmycin soluble powder 600-800 times liquid spray, or 72% streptomycin sulfate soluble powder or neomycin oxytetracycline 4000 times liquid, 50% enemy dry double wettable powder 800 -1000 times solution, 50% succinylphosphine aluminum wettable powder 400 times solution, 86.2% cuprous oxide wettable powder 1500 times solution, 10% phenyl ether methyl carbazole water dispersion granule 2000 times solution, 25% green Ling Wettable Powder 800 times solution, 20% thiabend copper suspension 600 times solution, 80% waveÂ·manganese zinc wettable powder 500-600 times solution, 12% copper rosinate emulsifiable concentrate 500 times solution, 25% copper ammonia solution 500 times solution, 77% copper hydroxide wettable microgranule 400-500 times solution, 50% succinic acid copper WP 400 times solution, 88% hydratedmycin soluble powder 500 times solution, etc. Fill the prepared liquid with 300-500 liters. Once every 10-15 days, even 2-3 times, pay attention to alternating medication. In the pre-onset or early onset of drug use, focus on the root of the disease center plant, the disease is blocked, to prevent spread. Serious illnesses will develop according to the condition and increase the number of medications if necessary.
You can also use the following compounding agent to fill the root: 88% hydratedmycin soluble powder 500 times solution + 20% thiabend copper suspension 500 times solution, 2% spring seromycin water 500 times solution + 80% mancozeb Wet powder 600 times solution, 3% carbogen WP 1500 times solution + 20% thiophanate-methyl WP 600 times solution.
Injection: use 2,000 times liquid suspension + 1500 times solution of the plant gene activator, and use the medical disposable syringe to directly inject the liquid into the diseased plant. The severe diseased plants (the whole plant leaves are sag) ML, light disease strain (partial branch leaves wilting) 3 ml per plant, injected from the middle and upper parts of the plant (the xylem is very hard in the middle and lower parts of the plant, the injection is difficult), the cure rate can reach 100%, and the effect is remarkable. The bacteria are directly injected into the main stem of the plant, and the bacteria of the main stem vascular bundle are quickly killed, the transport function of the vascular bundle is restored, the diseased plant is quickly restored, and the plant gene activator is added to activate the tomato plant. Excellent genes (growth, disease resistance, stress resistance genes), so that the diseased plants can quickly resume growth, improve disease resistance, stress resistance, and resist the re-infection of tomato bacterial wilt bacteria.
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