In recent years, with the adjustment of the agricultural industrial structure, the cultivation area of ​​yam has increased year by year, which has brought considerable economic benefits to farmers. However, due to repeated cropping, the yam has suffered from short-term nematode disease, especially in the years with heavy rain. Especially serious.
First, the symptoms of the disease
From the next species to the harvest, yam is harmed by short-body nematode disease, and it shows symptoms when the temperature is high in mid-September. The upper part of the ground showed pale leaf color, and the plant was dwarfed. When the disease was heavy, the whole plant turned yellow and even died. The light brown spot appears first in the upper part of the root, and then gradually develops into an elliptical dark brown lesion, which then expands into a piece and finally becomes an irregular black spot. When the roots are stored, if the conditions are appropriate, the lesions will continue to spread and spread, and the affected area gradually loses water and the epidermis cracks.
Second, the law of incidence
The pathogenic short-lived nematode is a colorless, transparent, unconformated invertebrate with a body length of no more than 1 mm. The developmental temperature is stopped at 16 ° C - 28 ° C, below 10 ° C, and the lethal temperature is 50 ° C ( 5 minutes), mainly distributed in the deep soil layer of about 20cm. The long-term damage period can be harmful in the whole growth period of yam, and the transmission route is mainly soil transmission and seedling propagation.
Third, prevention measures
1. Excellent selection: The yam black spot disease is mainly transmitted through seed transmission, especially in cross-regional introduction. Therefore, it is especially important to choose disease-free varieties. Usually choose the pure, disease-free, robust seedlings in autumn and winter every year. Avoid the multi-generation degraded species and diseased seedlings with slender neck, sharp bottom, and enlarged pores. It is best to use a generation of disease-free breeding to optimize the cultivation of disease-free seedlings.
2. Optimized cultivation: choose disease-free sandy soil with high topography, low humidity, fertile and loose, ploughing before winter, winter and spring. Deep sorghum planting, pay attention to drainage during the rainy season. Before sowing, apply the fermented organic fertilizer, increase the application of phosphorus and potassium fertilizer, 200kg per mu of cooked cake fertilizer, 50kg high-quality ternary compound fertilizer, and enhance the resistance of Yam to disease and disease. Cultivation insists on double membrane germination in advance, covering the mulch film, in order to facilitate early promotion, early listing, and reduce disease.
3. Reasonable rotation: Reasonable rotation can effectively reduce and avoid the harm of yam short-worm nematode disease. More than 3 years of rotation, especially water and drought rotation, the disease prevention effect is good.
4. Chemical control: cultivation in the new yam area, soaking in the pre-sowing section with 40% gram of phosphorus 1000 times solution for 48 hours, during which it is turned 2 to 3 times. After the removal, the lime powder is placed on the incision and dried to promote germination. In the ward cultivation, in addition to the soaking of the liquid, it must be combined with the application of soil before sowing. Use 3% mil or 5% gram of granules for 5kg per mu, or use 10% kedan granules for 3kg, add water spray. Mix 100kg of moist fine soil, spread the ditch evenly on both sides of the seedlings, or mix it with organic fertilizer such as decomposed cake fertilizer, evenly spread it, and mix it into a gentleman (depth 25-30cm).
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