Do you mean the leaves and the blossom are affected on that branch, or just the blossom?

Hi
Thanks for replying. It has finished blossoming, the leaves are brown & failing. Suggest something I can do to save the tree please.
Thank you

A photograph would be very useful, and you should inspect the whole tree, including the trunk, all the branches, stems, backs of leaves, for signs of infestation or infection. Hard to say what's caused it without photographs or more background info (how long have you had it, which sort of cherry, where's it growing) but, if its possible, and its only a small branch, remove it at its base where it joins the trunk or main branch.

Hi
I will check for signs of infestation. I have it in my garden for over 10 years. Thank you for your help, I will keep you updated.