When the suburbs boomed after World War II, the Callery pear tree was chosen to line their many miles of tree-lined streets. It had beautiful flowers and foliage, grew quickly and was hardy. Over time, however, problems surfaced. The Callery pear's flowers stank, its branches flew off in the wind, and it had a nasty habit of spreading to where it wasn't wanted. Now it's being banned in some states as an invasive species. Controlling Callery pears is difficult because of their extensive root system. You can dig them out if you remove every last bit of that. Otherwise, stay on top of the tree's growth by removing suckers regularly. And there are plenty of beautiful native tree species to plant in the Callery pear's place.