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Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

Rice blast (252)

Photo 1. Diamond-shaped spots on the leaves of rice leaves caused by blast, Magnaporthe oryzae.

Photo 2. Infections at the nodes of stems below the neck, caused by blast, Magnaporthe oryzae. The infections occur beneath the flower head and can lead to death of the stem.

Summary

Worldwide distribution. On rice and wild grasses. An important disease.
Spots oval or diamond-shaped, 5-15 mm, with whitish-grey centres and dark brown borders, merging, killing the leaves. Rots of leaf sheath, stem and panicles. Plants killed until tillering stage.
Spread of spores in irrigation water and by wind.
Cultural control: sow to avoid flowering at wettest times; avoid overlapping crops; split N applications; space plants to maximise air flow; collect and burn trash after harvest. Use chemicals at heading stage.
Chemical control: Seed/field treatment: mancozeb, captan (protectants); azoles, strobilurins (eradicants).

Common Name

Rice blast

Scientific Name

Magnaporthe oryzae. Previously, Magnaporthe grisea. Pyricularia oryzae is the asexual name.

AUTHOR Grahame Jackson
Photos 1 IRRI Rice Knowledge Bank; information (and Photo 2) CABI (2015) Magnaporthe grisea (rice blast disease) Crop Protection Compendium. (https://www.cabi.org/cpc/).

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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