Rust On My Privet Hedge

Hi everyone!

Ive noticed about two weeks ago that my 80ft long privet hedge is starting to drop leaves at a rapid rate. Most of the leaves that are dropped are what to me look like they are covered in rust.

I'm not sure what to do. There is lots of new growth which has covered the problem and the rust only seems to affect last years growth at the moment.

Would it be a good idea for me not to cut back the hedge this year so it can concentrate on fighting the disease instead?