Planted the tree in the fall of 2010. I believe it is a Cherokee Princess Dogwood. The leaves always seem to be withering and it grew very slowly. Here are some photos taken recently. I have used BioAdvanced Tree and Shrub for the past two spring, but it does not seem to help. I live in Washington DC with Hardiness Zone 7a (0 to 5 °F/-17.8 to -15 °C). Could anyone help me to identify the problems? Thank you.