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Asparagus stem blight symptoms and prevention methods
Asparagus is a valuable vegetable with excellent taste. With the continuous improvement of people’s living standards, the demand for asparagus in domestic and foreign markets is increasing. Because asparagus has strong drought tolerance, it is particularly suitable for planting in Tianjin. However, with the increase in the number of years of planting, the increase in the area, the occurrence of stem blight worsened, and the incidence of some plots reached 80% or even the destruction of the entire field, seriously affecting the healthy development of the asparagus planting industry. Therefore, early detection of disease symptoms and timely adoption of comprehensive prevention and control measures should be the main method to prevent both the symptoms and the symptoms, which is particularly important. First, the onset of symptoms The lesions occur mainly on stems, occurring first in the near-surface part of the tender stems, initially as small, milky-white spots, and later gradually expanding into spindle-shaped or spindle-shaped spots of small stains that gradually turn brown. The center is gray-brown, sag, scattered small black spots (ie, conidia). When the lesions are severe, the whole plant grows. When the lesions circle the stems for one week, the whole plant will die and die. Second, the prevention and control methods 1, selection of disease-resistant varieties, do a good job in seed treatment Currently, the introduction of foreign Mary Washington No. 500 compared stem borer disease. For preferred seeds, warm soaking or chemical treatment is performed prior to sowing. It can be soaked in warm water of 50°C for 10 minutes, and pay attention to pouring the seeds first and then stirring constantly to make the seeds evenly heated. Can also be used Fumei double agents such as seed treatment, has a good bactericidal effect, can reduce the occurrence of diseases. 2. Reasonably choose the land for asparagus to be placed in the soil with heavy weight, low-lying mat, close to the orchard, paddy fields and other places; while the high-lying, loamy or sandy soil blocks have good drainage and ventilation, and the environment is clean and the disease is less. . 3. It is more appropriate for close planting in Tianjin for dense planting in close rows (row spacing of 180cm and plant spacing of 50cm). Excessive density or improper intercropping within 1-2 years after planting will result in mutual obscuration, formation of a hot and humid microclimate, and the occurrence of diseases. It is particularly emphasized that it is strictly forbidden to make any crops in the field. 4, timely and reasonable fertilization and drainage Asparagus growth is large, the amount of fertilizer is also large, it should be timely fertilizer, in particular, to apply the base fertilizer. Apply 5,000 kg of organic fertilizer per 667m2 to see if the seedlings are topdressing fertilizer. Asparagus is a hi-phosphorus potassium crop, and care must be taken not to apply nitrogenous fertilizers to ensure the nutritional needs of asparagus, to grow robustly, and to increase its resistance to disease. In the rainy season, timely drainage is required to reduce the humidity of the shoots and reduce the spread of germs. 5. Timely cultivating weeding and weeding not only affects plant growth, but also exacerbates disease spread. Weeding and weeding to remove dead stems and leaves in a timely manner will facilitate ventilation and light transmission, and reduce the occurrence of diseases. 6, do a good job wintering winter or spring, should do a good job in the Qing dynasty. All remaining stems and leaves on the ground should be cleared out of the field and burned to reduce the source of bacteria. Before and after spraying the soil or stem and dish with 50% carbendazim 1000-1500 times solution or 70% thiophanate-methyl 1000--1500 times before and after April, the primary infestation source can be greatly reduced, and the disease can be controlled as soon as possible to prevent and treat as soon as possible. 7. At the peak of onset, adherence to chemical control in the rainy season during the July-August rainy season in Tianjin is the peak period for onset of asparagus stem blight, and it is necessary to insist on spraying once every other week. Common agents are: 75% chlorothalonil 600 times; 80% dexamethasone 600--800 times; 70% thiophanate-methyl 1000 times. Due to stem maturity affecting its susceptibility, the onset was first on the tender stem. Therefore, when spraying, it should be targeted and the newly emerged tender stem should be the main target in order to strive for better control effects.