Rice blast

Causal organism: Pyricularia oryzae (magnaporthe grisa)

• It infects plants at any stage of growth and stunts the plants.
• It reduces the number of mature panicle, weight of individual grains and the weight and quality of rice.
• High humidity favours development of lesions.
• Disease is more destructive in areas with more rainfall.
• Close planting or heavy application of nitrogenous fertilizer favours the disease.
• Plants with high silica content are less infected by blast.

Symptoms

• Typical leaf spots which are elliptical and somewhat pointed at both ends.
• Spots begin as small, water-soaked, whitish, grayish or bluish dots on susceptible varieties.
• Infection may occur in any part of the panicle, producing brown lesions.
• It occurs near the panicle base, causing 'rotten neck' or 'neck rot' symptoms.

Management

• Burn affected straw and stubbles.
• Grow tolerant varieties like IR-8, Jaya, Vandana, Hira, Savitri, Ratna, IR-36, and Annada.