First, the symptoms. General damage to individual grains, one to several grains per panicle. The diseased grains are dark in color. When mature, the inner and outer striated joints crack, and a large amount of black powdery chlamydospores are shed, and often the white tongue-like rice grains protrude from the crevice mouth, and black powder adheres to the top. Some of the diseased grains are dark green or dark yellow, do not crack, like green barley grains but the interior is full of black powder, hand pods have a soft feeling, a few of the diseased valleys are only partially destroyed, and some kinds of embryos may still germinate. Second, the incidence of law. The pathogenic fungus is mainly Pennisetum japonicus, black fungus, pathogenic bacteria wintering with the winter spores in the soil and seeds, during the flowering and filling of rice in the following year, the spores or secondary microspores are produced by germination of the winter spores on the surface of the water or moist soil. The airflow is transmitted to the flower or young grains to germinate and invade, destroying the formation of ovary and rice grains, and finally forming teliospores. Rice from the heading to the milky stage, especially after flowering, in case of rainy and humid weather, most susceptible to disease; partial nitrogen fertilizer, rice plant length or lodging, increased humidity between the plants, but also conducive to the germination of germination and invasion hazards. Third, prevention and control technology 1, agricultural control: Select high-quality disease-free rice seed, rice seed before sowing with mud or salt water, eliminate diseased grains; livestock and poultry manure after decomposing and then applied; avoid partial or late Nitrogen fertilizer. 2, seed disinfection: the disease can be used 0.2-0.3% triadimefon wettable powder seed dressing, can also be used to disinfect the pesticide soaking, the method with rice smut soaking. 3. Chemical control of field crops: low-grass red rice fields, perennial heavy crop fields, susceptible field plots, and rice booting seasons should meet temperature, rain, and sunshine conditions, and should be held at the end of booting to break and full heading. For prevention and control once, use 40% perchlorate powder 60 grams or 15% triadimefone powder 100 grams per acre, and add 50 kg of water evenly to the upper part of the rice plant.
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