tiny circular holes
I have a Lime Marmalade Heuchera. It grew well last year and was absolutely fine, flowering well etc this year, planted in the garden on a freely draining slope with good air circulation and shade varying from dappled woodland to about 1-2 hrs sun. Suddenly, last week the whole plant ie EVERY leaf is covered in tiny pin head exactly circular holes. Nothing else visible on top surface of leaves but on under surface there are tiny circular flat brown spots between the holes. No evidence of grey pustules or black edges. Although I have slugs and snails , no slime trails nearby and the holes are too regular. No evidence of caterpillars. Is this rust and if so how can I remove affected leaves as every single one has suddenly succumbed. No other plants within 1 foot of it and no other Heucheras for about 10 foot and they are not affected.
Should I spray it with antifungal and keep fingers crossed ?. Help, I love this little plant it is so bright and cheerful.
If it is, I understand that they do their thing and exit stage left..