My citrus tree is not healthy. The leaves are falling off, and the twigs are becoming brown and dying:
In the middle trunk, where a large branch was pruned years ago, there seems to be some burrowing insect that's causing saw dust and what looks like tunnels.
Also I've been scraping black scale off the citrus and have sprayed with white oil, pyrethrum spray.
Any other ideas about what could be happening? What should I do about it?