Pear fungus

[BuckmasterTreeService]

What is this? It is on almost every leaf of a bradfordish pear tree. It hasn't entered the stems. What treatments would be recommended if any?

 

[JD3000]

Gymnosporangium rust. Alternate hosts are junipers.

Been popping up more and more over the last couple of years so it's probably a newer or less common species than the big 3 we normally see on Rosaceous host: cedar-apple, cedar-hawthorn, and cedar-quince.