Fungus on young apple tree

The Tree is of an friend of mine and sits on a sun embraced place. Last year leaves started crumbling and dropping early in summer, no spots or necrotic leaves. also it was a very hot year so we didn't think or do much about it, just little more water in the morning. This spring (also very dry and hot) the leaves started crumbling even earlier, and also this fungus appeared. In the neighberhood theres an apple tree with simliar looking spots like on the second picture, but more developed so i guess our tree was infected over spores this spring while weak? Now im struggling to identify the fungus and asking for your help. Also i transfered some spores from the red leaf on an agar plate for microscoping, but it takes a few weeks until the sporangi develop and i guess we need to do something about it soon. Thanks for your attention and any advice given!!