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Overview Rice Blast is a devastating fungal disease caused by the fungus Magnaporthe oryzae. It is one of the most destructive diseases of rice worldwide, capable of causing significant yield losses. The disease can infect all above-ground parts of the rice plant, including the leaf, collar, node, neck, and panicle.
Key Symptoms - Leaf Blast: Lesions appear on leaves as diamond or spindle-shaped spots with gray or white centers and brown or reddish-brown borders. - Neck Blast: The neck of the panicle turns black and shrivels, a symptom often referred to as "rotten neck," leading to unfilled grains or broken panicles. - Node Blast: Infected nodes turn black and become brittle, often causing the plant to break at the node.
Favorable Conditions - High Humidity: Relative humidity above 90% promotes spore germination. - Moisture: Frequent rainfall or long periods of leaf wetness. - Temperature: Cool daytime temperatures (20-25°C) favor disease development. - Nitrogen: Excessive use of nitrogenous fertilizers increases plant susceptibility.
Disease Management & Control 1. Seed Treatment: Treat seeds with Tricyclazole 75 WP at a rate of 2g per kg of seed before sowing. 2. Chemical Control: If symptoms appear, spray Tricyclazole 75 WP (0.6g/L) or Isoprothiolane 40 EC (1.5ml/L) of water. Ensure thorough coverage. 3. Cultural Practices:
- Avoid excessive nitrogen application; split nitrogen doses.
- Plant resistant or tolerant rice varieties suitable for your region.
- Maintain proper water levels in the field to reduce drought stress, which predisposes plants to blast.
- Destroy infected crop residue (stubble) to reduce the fungal inoculum for the next season.
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Prepared by KhetiSetu Agri-Expert
KhetiSetu Plant Clinic Expert Team verifying and curating agricultural disease data for farmers.