Some of my summer raspberries have developed a bright yellow fungus on the underside of the leaves. I have doused them with stinging nettle tea but this adds calcium though does seem to have perked them up. Might make some with roof water. We have not had much rain, soil is very well drained and the site windy so no ventilation problems. It is only on the underside of the leaves and does not look like the pic on the RHS site. More like the one on American sites called late rust.
I also have some summer raspberries which cropped well but have also decided to flower on the new growth, do you think it best to cut it off.