The prevention and control of rice diseases shall follow the principle of "prevention first, integrated management, green and reduced use of chemicals". Scientifically rational application of pesticides and the promotion of pesticide-reduction technologies should be adopted, with a focus on controlling major diseases such as sheath blight, rice blast, and false smut.
1. Sheath Blight
Rice sheath blight is a fungal disease caused by Rhizoctonia solani. It mainly affects leaf sheaths and leaves. In the early stage, dark green, water-soaked, oval lesions appear on leaf sheaths near the water surface, gradually expanding into cloud-like patterns. Under high humidity, white mycelia and dark brown sclerotia are produced.
Control measures should be applied when the diseased plant rate reaches 20% from the late tillering stage to the booting stage, and again at the early heading stage (panicle protection). Suitable fungicides include Validamycin A, Jinggangmycin·Bacillus laterosporus, Polyoxin, Hexaconazole, and Thifluzamide.
2. Rice Blast
Rice blast is caused by Pyricularia oryzae and can occur throughout the rice growing season, affecting seedlings, leaves, panicles, and nodes, referred to as seedling blast, leaf blast, panicle blast, and node blast, respectively.
For seedling blast and leaf blast control, apply fungicides when the first lesions appear in the field. Under weather conditions favorable to disease spread, a second application should be made 7 days later. Effective agents include Bacillus subtilis, Tricyclazole, and Kasugamycin.
3. False Smut
False smut is caused by Ustilaginoidea virens and occurs only on panicles, affecting individual grains. Initially, small pale yellowish-green fungal balls emerge from the glume gap, gradually enlarging and covering the entire grain. They turn dark green or olive, eventually cracking and releasing dark green powdery spores.
Preventive application should be carried out 7–10 days before heading (when the ligule of the flag leaf is level with that of the second leaf from the top). In case of prolonged rainy weather, a second application is recommended 7 days later. Effective fungicides include Jinggangmycin·Bacillus laterosporus, Trifloxystrobin·Tebuconazole, and Epoxiconazole.
