Hi Glenn, and welcome
As Daisy says we really need to know where in the country or world you are to help.
I have several of these tree philo's in my yard and they are entirely easy care. But mine are in the shade of a huge old oak tree, so moist, acid soil and dappled shade.
Question - what are the white things on the ground under the plant in your last picture? They look like shells. If somebody has mulched under those plants with shells that would not be a good situation for them - the shells leach calcium into the soil, changing the pH.
Also any information on other changes or maintenance that's been done to the landscape recently might give a clue to the problem. Especially fertilizer.
