Symptoms After emergence of rapeseed, water-stained spots appear on the stem base near the ground, and then fold back and fold. When the humidity is high, the diseased department or surface appears white cotton floc, namely the pathogen mycelia, cysts and sporangia. The pathogen Pythium aphanidermatum (Eds.) Fitzp. called Pythium aphanidermatum, is a flagellin subphylum fungi. Mycelium grows luxuriantly and appears white cotton floc. The mycelium is colorless, without a diaphragm, and has a diameter of 2.3-7.1 μm. Mycelia and cyst stalks are not distinctly different. The sporangia are filiform or branched, or irregular in size, ranging from 63-7254.9-14.8 (μm). The vesicles are spherical and contain 6-26 zoospores. The oocyte is spherical and has a diameter of 14.9-34.8 μm. Males are bag-shaped to wide-stemlike, with one or more filaments, mostly one, size 5.6-15.47.4-10 (μm). The oospore is spherical, smooth, and less than 14.0-22.0 μm in diameter. The fungus has a high frequency in places where the average annual temperature is high. Transmission routes and pathogenic conditions The pathogens overwinter in the 12-18 cm top layer of oospore and survive long-term in the soil. In late spring, the sporangia germinate under suitable conditions to invade the host with zoospores or buds. In addition, in soil The mycelium in the rot of the camp can also produce sporangia, which is caused by zoospores infesting the seedlings. The re-infestation in the field is mainly due to the production of sporangia and zoospores on diseased seedlings, causing more serious losses by spraying irrigation water or rain on roots close to the ground. After invading bacteria, the bacteria expands in cortical parenchyma cells, hyphae spreads among cells or cells, and then forms oospores in diseased tissues. The suitable temperature for pathogenic bacteria growth is 15-16°C. The suitable onset temperature is 10°C, and the temperature is higher than 30°C. The low temperature is unfavorable to the host's growth, but the pathogenic bacteria can still be active, especially the low-temperature and high-humidity conditions during the nursery period, which is conducive to disease. When the nutrients of the cotyledons of the seedlings are basically used up, before the new roots are solid, it is a disease-susceptible period. When the true leaves are not extracted, the carbohydrates cannot be rapidly increased and the disease resistance is weak. In case of rain, snow, etc., they are affected by cloudy or cold currents. Low ground temperature, weak photosynthesis, increased respiration of seedlings, increased consumption, resulting in elongation of young stem cells, cell wall thinning bacteria invade through invasion, therefore, the disease occurs mainly before seedlings grow 1-2 leaves. Dog Jerky,Chicken Jerky For Dogs,Duck Jerky For Dogs,Jerky Treats For Dogs Jiangxi Welton Pet Products Co., Ltd. , https://www.weltonpetcare.com
Control methods (1) Use varieties with low temperature resistance and strong cold resistance. Such as oyster oil No. 2, Rongyou No. 3, Jiangyan No. 1 and Yuyou No. 2 etc. (2) 40% seed weight 0.2% can be used for seed dressing or soil treatment. Pharmaceutics treatment soil method liquid, 95% badewing quality 4000 times liquid, 72.2% Precive water 400 times liquid, spraying 2-3L per m2 good liquid. (3) Proper close planting, timely drainage and drainage, reduce the humidity in the field, and prevent moisture from staying.