Rust on my Fuschias.

Have a look at https://www.rhs.org.uk/advice/profile?pid=163

Not tried spraying mine in view of their sensitivity to sprays.

Capsids are my biggest bug!

Is there rust on anything else nearby? That's how my geraniums got rust last year or the geraniums started it,I don't know. Would a mulch help,if there's spores on the ground?

I was just googling & there's some info about using sulphate of potash as a top dressing around the affected plants,to help build plant cell walls.

"Potassium takes part in more than 40 enzyme actions which help control many plant functions. Of potassium's multiple roles within the plant, one important one is its work in building cellulose, a component of plant cell walls.
If conditions are suitable, a fungus spore will germinate after landing on a host plant and form a tiny root system known as a haustoria. This produces an organic chemical, designed to break down the cellulose barrier of the cell wall and allow the fungus to reach the sap stream, upon which it feeds. If the cell wall is thin, this is achieved with relative ease and the fungus flourishes while the host plant suffers. If the cell wall is thick, the fungal spore is unable to penetrate the cell wall and it eventually dies before it can reach the life-giving sap of the host plant."
Potash and Disease Factsheet - Gardening Australia - ABC