Jim Scott wrote:
I have a dozen or so hardy fuchsias in my garden. Some of them are flowering
fine, but a few are coming blind and the new leaves are small and twisted. I
see no sign of beasties or rust. I have now sprayed with insecticide and I
kept them moist during the dry spell.
Anyone recognise the symptoms?

Aha! The dreaded Capsid bug! Otherwise known as 'Sheild bug' or
'Stink bug'. It is a glutton for young Fuchsia shoots and clambers
about, sucking the sap in much the same way as greenfly. Because it is
much larger and directs its attention to the centre of young, emerging
shoots, the damage caused makes them go 'blind'. You could try a
systemic insecticide, but it isn't always effective since by the time
the bugs have taken a lethal enough dose, they've usually done the
damage. Fuchsias affected in this way, normally branch out and flower,
albeit later than expected.