Girdling roots occur when the tree roots circle and coil around the base of the trunk rather than spreading outwards. Think about the effect of wearing a belt that is too tight around your waist and you get the idea of what tree roots do when girdled. Girdling restricts the flow of water and nutrients to the tree, making the tree weaker and more unstable. While maple and linden trees seem the most susceptible, girdling can happen to nearly any tree.
What Causes Root Girdling?
Girdling roots are a common problem for trees in urban environments due to the factors those trees face that trees in nature avoid and those issues are related to a lack of space for proper root growth. Improper planting or transplanting is a significant cause of root girdling. If a tree is in a container or burlap for too long, the roots will eventually circle the trunk or container. If those roots are also not loosened during the planting process, the roots become girdled.
Signs of Root Girdling
Spotting root girdling is relatively easy, as plenty of signs can indicate that a tree has girdled roots. The most obvious sign is an abnormal trunk flare. A tree trunk typically flares out and widens at the ground, but if a tree has girdled roots, the trunk may appear straight or narrow, looking more similar to a telephone pole than a tree. Roots circling above the soil line may also indicate girdling, as can sunscald or frost cracks visible on the trunk.
Because girdling roots prevent trees from getting enough water and nutrients, other possible signs include the following:
- Thin or sparse canopy
- Die-back in the upper tree canopy
- Wilting, scorched, off-colored (yellow), or smaller than average leaves
- Early fall color and leaf drop