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The Disease:  BLAST
Pyricularia oryzae (Cav.)

Etymology: from pirum, pear shape - describing the spores
Blast is one of the most widely distributed rice diseases. Losses due to blast are difficult to estimate because other factors complicate the disease. However, losses are always significant.
Pyricularia oryzae produces spots or lesions on leaves, nodes, panicles, and grains, but rarely on leaf sheaths.

Leaf spots are spindle-shaped with brown or reddish-brown margins, shy centers, and pointed ends. Fully developed lesions normally measure 1.0 - 1.5 cm in length and 0.3 - 0.5 cm in breadth. These characteristics very with the spots' age, susceptibility of the cultivar, and environmental factors.

When nodes are infected, they become black and rotten. Infection of the panicle base causes rotten neck or neck rot and causes the panicle to fall off. In severe infection, secondary rachillae and grains are also affected.


pyricularia oryzae microscopic neck blast

leaf blast
Last Updated on Wednesday, 15 April 2009 07:15