What causes a dogwood tree to only have leaves and blossoms at the end of the branches? The branches are 6 to 8 feet long, but only 18 inches have leaves and blossoms on them. Why?
Leaves on Dogwood Tree Branches
If this problem only appeared this year, I would think that the hard winter is probably the culprit. give the tree plenty of TLC, and see what happens next year. If branches are still bard, it might be time for a bit of pruning to see how that affects the tree. Effects of a bad winter may take 2 or 3 years to go away. https://www.gardeningknowhow.com/ornamental/trees/dogwood/trimming-dogwood-trees.htm
In the meantime, here's some more information on growing healthy dogwood: https://www.gardeningknowhow.com/ornamental/trees/dogwood/dogwood-tree-not-flowering.htm