If you have a flowering cherry (prunus) with large areas which haven’t bloomed this spring, it is likely it has witch’s broom. Those branches will sprout much denser foliage than the rest of the tree and will take over the tree if left unchecked. Mark the base of the affected branches (spray on paint cans are good for this) and cut them out in summer which is the time for pruning these trees. Cherry trees of Japanese origin are particularly vulnerable to this affliction and if you don’t do anything about it, you will end up taking out the entire tree because it will not flower at all.
“The best way to get real enjoyment out of the garden is to put on a wide straw hat, hold a little trowel in one hand and a cool drink in the other, and tell the man where to dig.”
(about whom information is hard to find, beyond this particular quote).