My Potato Tree Vine is in trouble, big trouble

Can someone help me?

I have a beautiful 15 year old Potato Tree Vine. Just in the past two years it has started to suffer (yellowing leaves, branches dying off, splendor diminished). I just noticed it has whitish patches on the bark of the branches (not raised or crusty, just seems to be in the bark itself). The patches are about an inch long and slightly less on their width. I would be crushed to lose this beautiful tree. Any ideas would be much appreciated.

thank you

Can you take a picture of the white?

I am not sure if my camera works, but I will try. Thank you Calalily.

That should help us try to help you. Sometimes what you are describing and what we see in our mind's eye are two different things.