Bit hard to tell from the picture, if it's a heavy scale infestation there should be some blackish mould on some of the leaves. Also if it's scale you should be able to flick them off with a fingernail. You might also look for ants that 'farm' the scale for their 'honeydew'. If it is scale, a white oil or similar produce should do the trick. And if there are ants going up and down the tree, a ring of petroleum jelly around the base will stop them and interrupt the cycle.

Regards

Hi funnelweb

Thank you for your response. Since this post half the tree has died so I am not quite sure what has happened.

I do think it's scale covering the stems and there has been evidence of mildew. All that said there are no ants on the tree.

I have since trimmed it back and will see if new leaves appear. I've been wondering if the part death is due to root rot or a borer insect.

Thanks again for your advice

Yes, look, ants are not always evident with scale, and from your picture I'm not sure it is scale. It could be borers but that should be evident by small holes 'bored' into the trunk and branches. If you find those probe them with a piece of wire and see what you can extract. You can also inject methylated spirits into the holes which'll kill the bug in there. Having said that, I have a healthy, or what was a healthy, tababuia tree that is currently struggling to put on top growth although the lower braches have healthy leaves. I put it down to the long dry period just (hopefully) passed. By the way, Tababuia is not a tree familiar to the Sydney region. Good luck with it, hopefully what you've done will encourage it to recover.

Thank you again

The tree has some lesions as in the photo. I will try the wire to see what I find.

Ta