Identification: Black spots on beech leaves (Fagus sylvatica L.)

Hello,

a couple of my beech seedlings, grown from seed and now some months old, are unfortunately showing this kind of disease. I don't know what it is nor it looks like the most common beech diseases shown in google.

What could I do to cure this?

Thank you very much

 

Don't know about the specks but the stippling looks like that caused by a heavy mite infestation.