How to prevent and control rice bakanae disease? Treating seeds with chemicals is effective

Last year, rice bakanae disease occurred in quite a few places in Tongzhou District, Nantong City. The occurrence characteristics, infection pathways and control techniques of this disease are introduced below.

Bakanae disease can occur from the rice seedling stage to the heading stage, with the highest occurrence at the tillering stage. Seed-borne bacteria are the main source of infection, followed by diseased rice straw. When infected rice seeds are sown or covered with diseased rice straw, the pathogen invades through the coleoptile when the rice seeds germinate, causing the disease. Although bakanae disease can cause secondary infection, the pathogen mainly invades in the early stage, that is, the rice coleoptile stage, and the possibility of later infecting healthy plants and causing rice seedling disease is very small.

Rice bakanae disease is mainly caused by seed-borne bacteria; the soil does not carry the bacteria, so there is no need to treat the soil of diseased fields with chemicals. Treating seeds with chemicals before sowing is the most effective measure for preventing and controlling this disease. At present, the chemicals registered for seed soaking to control bakanae disease mainly include prochloraz, dithiocyano-methane (seed soaking agent), phenamacril, carbendazim · thiram, carbendazim · prochloraz · thiram, etc., among which prochloraz, dithiocyano-methane and their mixtures are the most commonly used. Due to many years of use of benzimidazole fungicides represented by carbendazim and their mixtures, the rice bakanae disease pathogen has developed relatively high resistance to such chemicals, and the related chemical prochloraz also has a potential risk of resistance. In recent years, the 25% phenamacril suspension concentrate developed by Jiangsu Pesticide Research Institute Co., Ltd. has been registered for the control of rice bakanae disease, with a recommended seed soaking concentration of 83.3-125 mg/L. This chemical has good control efficacy against rice bakanae disease and can effectively kill rice bakanae disease pathogens that have developed resistance to benzimidazole chemicals such as carbendazim.

In production, the seeds should first be sun-dried for 1-3 days, and seed soaking should begin after seed selection. Under normal temperature conditions, soak the seeds for 48 hours; when the temperature is low, soak for 60 hours. For rice seeds for machine transplanting seedling cultivation or seeds of susceptible varieties, the concentration should be appropriately increased during seed soaking. Sprouting at a lower temperature or soaking seeds without sprouting before sowing can reduce the occurrence of rice bakanae disease to a certain extent. Do not use diseased rice straw as a cover during seed sprouting; concentrating diseased rice straw for high-temperature composting or burning it can reduce the source of rice bakanae disease bacteria.