Rust On Roses

[mikesnr1]

I apologise if this is a poor question, but recently (during the last two weeks or so), and against the trend, many of my roses (up to 20/50) are exhibiting leaves spotting, then yellowing, finally dying. I've been very pleased so far this year because there was hardly any 'rusting' to be seen.
Can someone explain the nature of 'rust', and why it should attack "out-of-the-bue" in this instance? Many thanks in anticipation...

[Buenchico]

https://www.rhs.org.uk/advice/profile?PID=269

[Buenchico]

^^^ Note the link on that page to Black Spot, which might be your actual problem (rather than Rose Rust).

[Chipchopper]

If its 'rose rust' it can seem to hit randomly or when the plant maybe under stress from extreme weather.
fungal infestations such as this can be treated effectively with 'Bordeaux mixture'