Plant Health Alert - Excavate Root Collars to Save Trees - Henderson County Center

Plant Health Alert - Excavate Root Collars to Save Trees

— Written by Steve Pettis | September 19, 2024 (Updated: Jan. 9, 2026, 5:29 a.m.)

girdling roots — This paperbark maple tree in the Extension Office landscape was dying on one side. You can see that the trunk is flat on the dying side at the ground level. You can also tell the tree is planted too deep.

Most tree health issues can be traced to a LSREP...Lower Stem Root or Environmental Problem. LSREPs can be physical root damage, trunk damage, root diseases, etc. Always these tree issues are a serious threat to plant health.

girdling roots dying limbs — Limbs on one side of the tree were dying and the trunk was flattened on the same side.

Whenever I look at a sick maple, the first thing I do is excavate the root collar and look for girdling roots. Maples are notorious for girdling roots especially when planted too deep or mulched too heavily over years.

Girdling roots are roots that wrap around the root collar. This is caused by being planted too deep or if trees are planted while still in the burlap and basket. Also look for nylon strapping or any other object that can girdle the stem. Probe the bark to see if there are any dead areas on the lower stem.

Lichens are crusty creatures made up of algae and bacteria. They can be found growing on rocks, dead logs, and any other object that does not move. Trees should be adding girth annually. As stems grow, bark is shed and lichens cannot grow. So, when you see lichens on the stems of trees or shrubs, this indicates the tree has not grown well in the last years.

This Chinese elm was not growing because it was planted too deep. A root collar excavation was performed.

tree rescue — The tree several years later in 2020 had grown into a nice tree thanks to the root collar excavation.

In the case of the pictured trees, some root collars were buried 6-12”. Tree roots need oxygen; excessive mulch or soil piled over the root system suffocates the roots and plants die slowly.

To remediate plants that are planted too deep or buried in mulch, I recommended raking out the mulch from around the trees and shrubs, excavating the root collars (where the roots meet the trunk), and maintain mulch to a depth of no more than 2-3 inches. excavate the root collar (where the roots meet the trunk). This area should be exposed to the air and not buried in soil or mulch. This usually saves the tree.

Trees that have been buried for years can be rehabilitated. The shorter the amount of time between burying and rehabilitation the better of course. The soil must be removed back down to the original grade as much as possible. The root collar (the junction of the roots and the stem) should be exposed to the air. Aerating the soil around the roots using an air spade or auger and applying organic matter and low nitrogen fertilizer can help too.