HOW TO: IDENTIFY & TREAT GIRDLING ROOTS
There are times in the season when there is not much going on. Take this opportunity to inspect your properties for girdling tree roots. Roots can girdle the tree if they are growing around the base of the tree instead of radiating out. As both the tree trunk and root gain diameter, pressure is placed on the water and nutrient pipeline located just under the bark. Water and nutrients are unable to move up into the canopy of the tree and sugars manufactured in the leaves are unable to reach the roots. Eventually, the side of the tree with girdling roots will begin to suffer, possibly resulting in death of the branch or entire side of a tree.
As with many things, prevention is the best defense. Pay close attention to the rootball at planting. Look for any roots that are not radiating out from the trunk. Small roots will grow larger, so prune it out if growing across the trunk.
On young trees, inspect around the trunk for crossing roots that can develop into girdling roots. These are much easier to remove when young, prior to any damage. Take care not to damage the trunk or other roots.
On slightly larger trees, observe them from a distance. Look for declining branches or uneven growth in the canopy of the tree. Tree species that often have problems with girdling roots include pines, maples (excluding silver maple), lindens and magnolias.
Closer inspection may show branches with reduced growth or smaller leaves on one side of the tree. If the pipeline were still intact, the branches and leaves would look more vigorous. If treatment is possible, go back to these branches periodically to check for signs of recovery.
Observe the trunk. Just as we drew trees with a trunk flare when we were kids, there should be a flare radiating out from all sides of the trunk. Some species flare a lot, some not so much. If the trunk enters straight into the ground or if there is an indention in the trunk, something is blocking growth on that side of the tree.
Remove any mulch and carefully loosen the soil on the affected side with a trowel, knife or hand cultivator. Your goal is to remove the soil without damaging roots growing in the area. You may have to excavate 10 to 12 inches deep or more to locate the obstructing root or other restriction. In some cases, the girdling root may be sitting on top of the soil, stretched comfortably across the tree trunk.
As you excavate, you should see a root or roots growing across the trunk. It may be growing next to the trunk or the trunk may have begun feeling the pressure and enclosing the root.
You can remove smaller girdling roots using a chisel, pruners or saw. For larger girdling roots, you may want to consult with a forester on whether to try to remove the root and how best to perform the removal. Identification of the problem may be half the battle. You should backfill the area with mulch so that you can easily monitor the wound and recovery process.
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