Control Methods and Technical Key Points for Rice Bakanae Disease

Symptoms: After rice is infected with bakanae disease, the internodes of the affected plants elongate, growing thin and tall, the plant color is paler, the leaves are narrower than those of normal plants, there are varying numbers of adventitious roots inside or outside the leaf sheaths at the nodes, and white mold grows inside the rice stalks, later turning light red, sometimes appearing as small black spots. The affected plants head earlier, with smaller panicles and fewer grains, or become sterile grains. The surface of plants that die from the disease has a light red or white powdery mold, and at the seam where the inner and outer glumes of diseased grains meet, a light red mold layer grows.

Occurrence pattern and transmission route: The pathogen of rice bakanae disease overwinters on grains and rice straw. When diseased seeds or rice straw are used the following year, the pathogen invades through the coleoptile or wounds of the seedlings, causing the seedlings to develop the disease and grow excessively. After diseased seedlings are transplanted, the pathogen is carried into the field, causing rice seedlings to develop the disease. When rice heads and flowers, the pathogen spreads to the floral organs through wind and rain, causing grains and rice straw to carry the pathogen, cyclically infecting and damaging rice.

Control methods: The focus of controlling rice bakanae disease is on seed treatment.

Strictly disinfect seeds. Use 100 g of 50% carbendazim, add 50 kg of water for seed soaking; or 120 g of 35% Bakanae Ling, add 50 kg of water for seed soaking; or soak seeds in 3% quicklime water for 48 hours. When soaking seeds in the chemical solution, it must be noted that the liquid level must be 15--20 cm above the seed layer, for the seeds to absorb. At the same time, during the seed soaking process, the liquid surface must remain still, and it must not be stirred midway, nor reused, to ensure the pathogen is suffocated.

Whether in the seedling field or the main field, diseased plants should be pulled out promptly when found to prevent the infection from spreading. Diseased rice straw should be properly handled; it must not be thrown away randomly, nor piled at the edges of fields, nor used as a cover for seed germination, nor used to tie rice seedling bundles. It can be centrally composted at high temperature, and in severe cases burned.