I planted three Correa 'Tucker Time Dinner Bells' plants in my garden in Melbourne, Australia nearly two years ago. Two of them died within a month or so but this one grew well until about two weeks ago when the leaves at the back started drooping, curling up and drying out.
We've had some decent rainfall recently so I don't think it's just a lack of water. I watered it with some seaweed fertiliser when I first noticed it looking sad but that hasn't helped.
Some suggestions I've seen online for what might cause this are root rot or curl grub so I've had an exploratory dig around the roots but can't see anything obviously wrong. I have seen the odd curl grub in this soil in the past though.
There are Woolly Bushes and Kangaroo Paw growing in the same area that seem to be doing well but I have lost some Grevilleas in the past.
This area used to be lawn with some Plumbago plants closer to the wall. I tried to smother the Couch grass but wasn't entirely successful so there are still some roots which keep shooting up again. The soil was initially quite hydrophobic so I've added some compost and also watered with a wetting agent. I mulched with woodchips sourced from the local transfer station before these were planted.
What might be causing this?