I. Occurrence of rice smut disease occurs from flowering to milk ripening and only harms the grain. The number of diseased valleys per ear is between 1-2 grains, and up to 40-50 grains. The bacteria grew in the glume. The initially encroached grain husks opened slightly, exposing small yellow-green chunks, then gradually expanded, wrapped in whole glume, cracked in green, and scattered black-green powder. Viscous, not easy to fly, but it can be spread by airflow, infecting flower organs and juveniles when rice blossoms. Rice smut disease caused a decrease in rice grain weight and yield, and increased glutinous rice and broken rice. The rice yield and quality were reduced. The average yield loss is about 5%, more weight. Germs develop in July-August and grow in large numbers if the climate suits them. Infected rice grain from flowering, the diseased grain is dark green or dark green after maturation. The factors affecting the incidence of rice smut are closely related to the resistance of rice varieties, fertilization (especially nitrogen) and climate. Generally tight or late-maturing varieties are susceptible to disease, while the early-maturing varieties with scattered panicles are lightly diseased; the heading stage is more rainy, the sunshine is weaker and shorter, the dew is more, the fog is greater, the nitrogen fertilizer is heavier or later applied, and the incidence is heavy; the booting period is low temperature, Less rainy, less sunshine, high temperature after heading, high humidity, high incidence and heavy disease; germs develop well at 24-32°C, optimal for officials at 26-28°C, less than 16°C higher than 36°C cannot grow; high humidity It is conducive to the occurrence of diseases, especially in the days of heading and flowering, and rainy days, especially in deep water irrigation.
Second, prevention and control methods 1. Selection of disease-resistant varieties of rice varieties showed significant differences in resistance, and the use of disease-resistant varieties (such as Jin Xing Yi, Yu Yu 16, Fu Yu 18) for the prevention and treatment of rice smut economic and effective measures. 2. Improved Cultivation Measures The onset of rice fields is to be deep-rooted after rice is harvested so that sclerotia can be buried in the soil. Before sowing rice, pay attention to removing pathogens and field pathogens. Clear weeds in the field, apply reasonable fertilizer, use nitrogen, phosphorus, and potassium in combination, do not apply nitrogen fertilizers to prevent nitrogen fertilizers from being applied lately, overdosing, panicles are too much, and the water layer is too deep. Promote sparse planting, seedling growth, and improve ventilation and light transmission conditions. 3. Chemical control 50% Carbendazim 1000 times soaking for 48-72 hours. Seed disinfection. The shortest field application amount is in the late booting stage (ie about 5 days before rice breaks). (1) Use 20% Jinggangmycin 37.5 g per mu or 50% Jinggangmycin 500 times to control. (2) Apply 50% carbendazim WP 100-150 g per acre to the water. (3) The water is sprayed with 180-200 grams per mu.
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