I was admiring the glorious display of Primrose in a local wood when I noticed that many of the plants’ leaves had yellowish spots on their upper leaves. Rust, I thought, and, sure enough, on turning the leaves over, I could see the tiny cup-shaped aecia on the undersides, which confirmed this as Primrose rust (Puccinia primulae).
I found this second rust during today’s woodland meander. It’s Melampsora populnea on Dog’s mercury (Mercurialis perennis). Once again, there are yellowish marks on the upper leaves and, this time, rather than cups, there are minuscule splodges of yellow underneath. Neither of these rusts seems to do much harm to the plants.