Podosphaera plantaginis (Erysiphales, Ascomycota)

Powdery mildew (UK) 
Härmäsieni (FIN) 
Mjöldagg (SWE)

Podosphaera plantaginisis an obligate fungal pathogen infecting Plantago lanceolata. During the summer P. plantaginis propagates as clonally produced spores that are dispersed by wind. Towards the end of the growing season sexually produced resting spores begin to appear. Infection is clearly visible as white-greyish mycelial growth on the surface of the host plant. Every year local pathogen populations crash as the host plant dies back to rootstock.

Powdery mildew on ribworth plantain