Roots girdling the trunk
- Circling roots cause trees to lean
- Girdling roots cause stress and decline
- Girdling roots kill trees
- Remove girdling roots from landscape tree
- See: Remove girdling roots on young container tree
Roots that are not directed away from the trunk can cause health issues for the tree, and tree death in certain cases. Look for roots that are circling close to the trunk, roots that are embedded in the trunk, or those that are crossed over main roots at the base of the trunk. Roots circling or touching the trunk are often referred to as stem girdling roots. These can reduce the flow of water, nutrients, and sugars at this point on the trunk. On some species of trees, stem girdling roots cause death to the bark above the root.
Treatment: If these are less than about one-third the trunk diameter, and they can be removed without damaging the trunk, then carefully cut and remove them (see photos below). This will allow roots and trunk under the girdling root to develop properly. Some arborists have removed larger girdling roots with no adverse affects on the tree. Trees often respond to removing girdling roots with increased vigor.
This shows a stem girdling root growing in mulch placed on the trunk at planting. Keep mulch pulled back about 12 - 18 inches from the trunk to prevent this. Note the trunk injury (extreme left on trunk) caused by the girdling root.
After removing the stem girdling root, the root system and trunk below this point can expand normally. Notice the indentation in the trunk where the root was removed. The root wrapping the trunk restricted the trunk from expanding at this point. It is easy to see why these are not good for trees.
This stem girdling root was visible at the surface without removing soil or mulch. Carefully cut the root at the point where it emerges from the trunk and remove as much of it as possible without damaging the trunk and other roots.
The tree on the left center is declining from stem girdling roots. One of the trees in this photo is also beginning to show signs of stress from girdling roots. This downtown shopping district will look very different with these trees replaced with new young trees.