How to prevent rice smut

Rice smut is also known as head smut, and Umi Valley is an old disease on rice. It is distributed in many countries in Asia, the Americas, and Africa. It occurs in the Yangtze River basin and in the south of China. In the past, due to the lightness of the incident, no special control was required. With the promotion of hybrid rice, the disease has become increasingly serious. In normal years, the disease rate is 5 to 20% (disease rate is almost the rate of yield loss), and the year of severe disease can reach 40 to 60%, becoming the primary disease of hybrid rice production. This disease is a foreign quarantine subject and deserves special attention.
Disease characteristics The disease only harms the grain, and the disease can only be found when the rice matures. The diseased grains appear as dirty green or yellowish (more clear with water-soaked diseased grains), sometimes with a dark tongue protruding from the inner shell. The diseased granules are filled with black powder. After the diseased pods are opened, the black powder is released. This is the pathogenic chlamydospore.
Rice smut is caused by the fungus of Pennisetum japonicum, and the pathogen is overwintering on the seeds and in the soil with thick buns. Chlamydospore has strong resilience, and chlamydospores in the soil (paddy fields and drylands) can survive for 3 years. Dipping in constant temperature water at 55 degrees Celsius for 10 minutes still survives. After passing through the digestive tract of poultry and livestock, chlamydospore can still germinate and spread to rice by airflow.
When the rice blossoms, the pathogens invade the flower buds, the peak of the infection is the initial flowering period and full flowering period, and the flowering period is the main one. There was also infestation before breakage and after flowering sowing.
Conditions of occurrence Hybrid rice planting fields have serious diseases in the early years, and the amount of residual bacteria in the field is large. The occurrence of diseases in the second year is also heavy. In the case of re-application of nitrogen fertilizer and high humidity in the field, it is conducive to disease occurrence. Why the maternal and maternal breeding fields in hybrid rice production fields have serious diseases, because the female parent (CMS line) of hybrid rice has a long flowering time, a large angle of opening of the glume, and a high stigma exsertion rate, which is conducive to improving the outcrossing rate of outcrossing. However, these traits are extremely beneficial to the occurrence of rice smut caused by co-infestation.
Control methods
1. Minimize the initial infestation of manure source and maternal breeding plots, implement crop rotation or winter ploughing to plant spring crops; Seeds are first selected through a selection machine, and they are planted with 8% saline to eliminate 90% of the disease. grain. After the sterilization of the drug, it can be considered to use 20% of triadimefon emulsion 500 to 1000 times or 50% of carbendazim wettable powder 500 times, soaking for 5 to 6 hours, remove and wash, and then germination.
2, strengthen the cultivation and management to enhance rice disease resistance, Shizujifei, avoid excessive application of nitrogen fertilizer, Shen Shi Pan fertilizer. Shallow irrigation, timely exposure of fields.
3. Chemical control This is still one of the most effective measures to control rice smut. The new fungicide -30% Ai Miao EC produced by Swiss Syngenta Crop Protection Co., Ltd. was tested and demonstrated in the southern rice region for more than three consecutive years by the Agricultural Technology Extension Service Center of the Ministry of Agriculture of the People's Republic of China. Foul disease is very good.
With 30% Ai You EC, 15 to 20 ml per mu, and 30 liters of water, each of the 3 to 7 days before rice breaks and the first ear, the control effect reached about 90%, which was significantly better than common pesticides.
Author unit: Hunan Plant Protection Bureau

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