Sometimes a tree’s trunk doesn’t rise elegantly from the ground. Small sprouts or stems stick up around the base.
These are called “suckers,” and it’s best to cut them off close to the ground, according to the Plant Clinic of The Morton Arboretum. If you neglect suckers, a tree may come to be surrounded by an untidy ring of them. They compete for water and nutrients with the main tree.
Tree suckers can occur for a couple of reasons. In some cases, they indicate that the tree is stressed. For example, when emerald ash borer larvae have killed off the upper branches of an ash tree, it usually responds by sending up a cluster of suckers from the base in an attempt to stay alive.
Suckers may also appear higher on the trunk in a stressed tree, especially around pruning wounds or cracks.
Another common reason for suckers is that the tree is grafted.
Grafting is an ancient technique, used for thousands of years, that involves growing the top of one kind of plant on the roots of another kind that may be more hardy or disease-resistant or that develops roots more easily. Usually, the two plants will grow together, so the bottom plant, called the rootstock, supplies water and nutrients to the top plant, called the scion, which bears the branches and leaves.
However, sometimes the rootstock will send up shoots of its own. If you see that suckers at the base of a tree trunk have different leaves from the rest of the tree, they are probably growing from the rootstock, which may be another species. You may be able to see the graft union, a bulge or change in the bark where the plants are joined, near or just below soil level on the tree’s trunk.
Ornamental flowering trees such as crabapple, cherries, and pears are usually grafted and often have suckers. As these trees age or are weakened by disease, the rootstock may send up more suckers.
An occasional sucker is not a big problem—you can just prune it out. It’s easier to regularly prune out small suckers than to wait until they get thick and hard to cut or accumulate into a bushy mass.
If you have a tree with lots of suckers around its base, they may be a symptom of stress. Have a tree professional assess the overall health and soundness of the tree.