oidia

/OY1 D IY0 AH0/
noun
  1. 1

    A fragile spore produced by some fungi.

  2. 2

    The fungus Erysiphe necator (= Uncinula necator), which produces powdery mildew in grapes.

Source: https://en.wiktionary.org/wiki/oidia, https://en.wiktionary.org/wiki/oidium