The first is Appendiculella calostroma, which causes dark, blotches on the surface of sheltered bramble leaves at this time of year. The blotches often merge together to form blackened, sooty looking areas on the upper surface of the leaves and stems. Look closer and you will see that each blotch is a diffuse, dark web, with black blobs on it, near the middle.
|It looks shiny in this pic, because the leaf was wet, When dry it is matt.|
Don't be fooled bt the purple spots that are common in brambles, Those are caused by the rust Phragmidium violaceum. The easy way to be sure is to look underneath the leaf. The purple spots of P. violaceum are visible on both sides, with a black felty looking spot (the spores) often present in the middle of the spot under the leaf. A calostroma is usually found only on the upper surface and can be scraped off.
If you look closely at Herb Robert (Geranium robertianum) at the moment, you will sometimes find lots of these tiny black dots on the leaves and petioles. It is a microfungus called Coleroa robertiani.
|The black dots are the fungus. What the springtails are eating, I don't know.|
|Two for the price of one. Diaporthe samaricola on the thicker areas and the much|
smaller Phoma samararum (Stagnospora samarorum) on the thin wing area.