Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens & Weeds

Rice blast (252)

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 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
Information from BugwoodWiki (2014) Magnaporthe oryzae. (https://wiki.bugwood.org/Magnaporthe_oryzae); and Blast (various articles). Rice Knowledge Bank. IRRI. (http://www.knowledgebank.irri.org/search-results?gsquery=blast); and Meng Q et al. (2019) Proteomics of rice - Magnaporthe oryzae interaction: what have we learned so far? Front. Plant Sci 29. (https://www.frontiersin.org/articles/10.3389/fpls.2019.01383/full); and (with Photo 2) CABI Magnaporthe oryzae (rice blast disease) (2019) Invasive Species Compendium. (https://www.cabi.org/isc/datasheet/46103): and from TeBeest DOC (2012) Rice blast. The Health Instructor. (https://www.apsnet.org/edcenter/disandpath/fungalasco/pdlessons/Pages/RiceBlast.aspx). Photo 1 IRRI Rice Knowledge Bank.

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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