Berberidposis corallina growing in a pot on a north facing wall the leaves have gone dry and brittle ,help!?

The plant is regularly watered and fed and has flowered each year for the past 4years

Berberidposis corallina growing in a pot on a north facing wall the leaves have gone dry and brittle ,help!?
If it's not under/over watering it could be a soil pest such as vine weevil grubs. if you can lift the plant out of the pot and have a little dig around. They are small white grubs with a brown head about 1cm and are usually curled up in a "C" shape. They devour the roots of pot plants and lead to the leaves drying up. You might save the plant by by using "Provado". cut back hard and feed with a liquid fert and wait for about two weeks, you may see some new shoots. If not i'm afraid it's probably too late

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