Clade 1 consists of Erysiphe, Microsphaera, and Uncinula, all of which have an Oidium subgenus Pseudoidium mitosporic state.

Clade 5 consists of Sphaerotheca, Podosphaera, and Cystotheca, which have Oidium subgenera Fibroidium and Setoidium mitosporic states.

The external mycelium gives rise to short, erect conidiophores, each of which bears a single row of barrel-shaped spores, the youngest being at the base (the affected parts become thus covered with a forest of conidiophores assuming a white powdery appearance).

The ripe spores become detached and are readily dispersed by the wind, causing fresh infection.

When the asci expand they rupture the cleistothecia wall, throwing the ascospores into the air.

Erysiphales are obligate parasites on leaves and fruits of higher plants, causing diseases called powdery mildews.