Pieris leaf drop
My pieris 'Flaming Silver' lived out the front of the house (west facing) for several years where it survived being baked but didn't grow much. A couple of years we moved it to the back garden against a north-facing fence where it seemed to flourish. But over the last couple of weeks, this has happened :
The soil is acid and sandy. It's generally dry, but being in the shade this positio maintains moisture better.
Can anyone suggest what the problem is, and what the chances of recovery, please?