I've have a Champaca tree growing well in my yard for about 4 years. For about the last year, I noticed a lot of leaf drop, and a LOT of dead, brittle branches. This spring it sported some new growth, but now the new leaves are brown and withered. I've added supplements to the soil that brought up the PH in the soil for a more acidic balance, and have been deep watering when my soil moisture meter shows not quite dry. I don't see any bugs. What is going on, and can I fix it? the first photo is about 3 months ago, the last tree photos were taken today.
What's killing my tree?