I have two Dwarf Poinciana (Caesalpinina pulcherrima) plants that are about three years old. A few weeks ago, one of them started turning yellow near the branch ends, and the yellowing quickly spread to the entire plant, and all the leaves fell off. Oddly, the plant was still blooming despite this event, but now all the flowers are dead, too. The other tree has a little bit of yellow on some leaves, but does not appear to be going into the rapid decline that affected the other tree. The only disease that UF says they're susceptible to is mushroom root rot. However, I don't see any of the tell-tale fungi that would indicate mushroom root rot as the cause.

Anyone have any experience with this? Is my tree dead? I have plenty of seeds and can grow a replacement shrub easily, but if I stick it in the same place will that spot be forever infected and kill the replacement, too?