A type of fungal spore (conidium) formed by the breaking up of fungal hyphae into cells, especially as produced by powdery mildews.
2A fungal disease affecting vines, caused by a powdery mildew.
- ‘The effects of phylloxera were first noted in France in 1863, just as the country was recovering from another great scourge of 19th century European viticulture: oidium, or powdery mildew, which was first noted in 1847.’
Mid 19th century: modern Latin, from Greek ōion egg + the diminutive suffix -idion.
We take a look at several popular, though confusing, punctuation marks.