what is this in my Hydrangeas?

My Hydrangeas are poorly! In the top the leaves are getting black and fall off. Bloom is also blackening. On the lower part of the hydrangeas the leaves are okay. What disease is this and how to treat?

 

It doesn't look diseased, more like a bit of cold damage. If you've had a touch of frost when the buds were forming, the new leaves as they open tend to split themselves up on the black bits. As for the mauve leaves, it looks like a preziosa hybrid. Do the leaves colour up nicely in Autumn?

 

Thank you very much for your reply! Yes, the leaves colour up nicely in Autumn. Its the Macrophylla At this moment I try to cut all the blackened leaves of all the 50 I have. It's now the second year with this disease. Blooms were last year not really great (parts were blackened) so I'm desperate to find out which disease it is and how to treat them. A lot of pages on Google not one with pictures of 'my' disease.....

 

As I said previously, don't look up disease, look up frost damage.

 

Thank you very much!