Answer: I don't really know why one of your three chitalpa trees is not thriving. It sounds stressed but other than soils that are too moist, there's no real reason for it to delay leafing out and flowering. I'd give it a little more time. The branches are obvioulsy alive so it appears to be trying to sort out some root stress. I'd just continue giving it good care and hope it leafs out soon. Wish I had more suggestions. Best wishes with your tree.
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