Septoria spec.
on Quercus

Quercus rubra, Belgium, prov. Antwerp, Geel, Gemeentelijke visvijver, 13.vi.2018 © Carina Van Steenwinkel

leaf spots, upper side

underside of a single leaf spot

conidia

conidia
parasite
Conidia 1 x 20-25 µm, 1-septate, with acute tips, no mucilaginous cap; no constriction at the septum.
host plants
Fagaceae
Quercus rubra.