Last spring I bought an 8' crepe myrtle. It partially bloomed, but I expected more flowers. Right now, 3 months into this spring, the tree appears dead, except for new stalks at the base. If I cut into the bark of the upper trunk, there is no greenery. The tree is in complete sunlight and watered by a lawn sprinkler system. Other new trees that I planted in the vicinity are flourishing. I invested a good some of money for the tree and would dearly like to see it thrive. Do I have any hope? I live on Long Island and believe I am in zone 6 or 7.