Has the air been too dry? Does it get enough light?

Could you post a close-up photo of the damaged areas?

Kt

It may be natural and will come back.
Both my Tuldoides and Vivax are dropping
tons of leaves now. The leaves turn brown,
then drop off. But if I look close, I can
see new leaves forming at the leaf joints.
For my money, you should just let it be.
If you aren't overwatering, overheating,
overfertilizing, or it's not to cold or
hot, it may be a genetics thingy and you
just have to let nature take its course.
Toto