Cercospora mercurialis  

Leaf spots circular to irregular, 2–3 (–5) mm diam., pale brown with a greenish brown border.
Anamorph: conidiomata absent. Conidiophores amphigenous, in clusters of 7-15, developing through stomata from a small immersed stroma, 20-45 x 4.5-7 µm, pale brown to brown, sometimes geniculate or sinuous, smooth, thin, irregular in width, usually narrower towards the tip, aseptate or sparingly septate, proliferating sympodially, the conidial scars 1–2 μm diam., conspicuous, thickened and darkened, terminal and lateral. Conidia 33-85 x 3.5-6 µm, cylindrical to filiform, straight to slightly curved, often gradually tapering, smooth, thin-walled, indistinctly multiseptate, the base obconical to truncate with a thickened and darkened hilum 1-2 µm diam., the apex obtuse.
Teleomorph: not known.