oidium

 
Pronunciation: /əʊˈɪdɪəm/

noun (plural oidia /-dɪə/)

  • 1 Botany a type of fungal spore (conidium) formed by the breaking up of fungal hyphae into cells, especially as produced by powdery mildews.
  • 2 [mass noun] a fungal disease affecting vines, caused by a powdery mildew.
    • The fungus is Uncinula necator (formerly Oidium tuckeri), family Erysiphaceae, subdivision Ascomycotina

Origin:

mid 19th century: modern Latin, from Greek ōion 'egg' + the diminutive suffix -idion