Plum tree diseased?

We have a 18-20ft plum tree in our garden. This year it flowered well in spring then no sooner did the leaves start growing, they also started dying. It's struggled through the year and is losing its leaves again now for Autumn but it still show signs of what I think is rust.

But I wondered if someone could confirm or offer a second opinion? Some other plants in the garden (antirrhinum and fuchsias) beneath it have developed rust too this year. I know rust doesn't necessarily transfer between species but it can't help having this raining own on plants all the time.