Ill mimosa tree
Jess is in the Garden
Posts: 1,022
It's about 10 years old, planted in an open bottomed raised bed, free draining site, south facing but with roots in shade all day. Never lacks water.
Loads of brown, bare, possibly dead branches on the crown and under the canopy at eye level.
Was happy and healthy until a few months ago, still flowered this year but not as much as in previous years,
Saw a few whitefly flying about, but can't see any infestation at the level I can see, no eggs or larvae on lower leaves.
Still, I put some lacewing larvae up there just in case (it's very warm here in south of France).
As leaves die back, they are reddish.
There are plenty of new leaves on healthy branches.
It shares a bed with some 
vinca majors and a couple fo small grasses.
Help! I love this tree and would hate to lose it.
sorry about photo position - they are all, the right way up on my iPad!
Posts
PS mimosa has never been ill before.
I would have thought it's got old and has run out of nutrients and water, despite what you say about it never drying out. I'm not saying you're wrong, just that, for some reason, the tree isn't receiving sufficient food and drink. That's how it looks to me. Perhaps reduce the canopy so that the roots don't have to supply so much
H-C
Thanks HC.
you may well be right, I fear. I will try thinning it out and removing all dead wood, then give it w ve good feed too. Here is hard paving around the bed, but it is on a Gardena watering system when we are away....however it wouldn't get many nutrients and not much if any rainwater, it's true.
any particular feed you'd recommend?
Blood, fish and bone or pelleted chicken and cow manure after a jolly good soaking and then fork it in loosely and give it a good mulch of decent planting compost and another drink.
Thanks Obelixx.
Ive given it a very good cut to remove as many of the dead bits I can reach, including reducing the crown which was all dead.
I'm very worried about it though, as from the photos below it looks ill to me. Is this some sort of dieback? Should the core be brownish black?!
it looks horrible ?
The green branches first seem to go entirely yellow, then develop black marks, that go through to the core, before eventually turning he whole stem black.
Anyone?
I've never seen it in person but that looks a lot like verticulum wilt to me. See what you think about this info from the RHS - https://www.rhs.org.uk/advice/profile?PID=255