Girdling roots

About

Girdling roots wrap around the base of a tree at or just below the soil line, choking the trunk as both grow. They usually start from planting too deep or from roots that circled in a nursery pot, and the tree declines slowly over many years.

Also called girdling roots, girdling root, stem girdling roots, circling roots, root-bound, rootbound, pot-bound

How to recognize it

Symptoms

The trunk goes straight into the ground with little or no flare, or has a flat, sunken side. Leaves are small, scorch, color early or drop early, sometimes on just one or two branches. Twigs and then big branches die back, the crown thins, and the tree may lean.

Often confused with

Drought and nutrient problems cause the same thin crown and scorch, and a lab can't find girdling roots from a leaf sample. The only sure check is to dig gently at the base of the trunk and look at the roots.

Worse when

Planting too deep, roots that circled in a pot, small planting holes, wire baskets, burlap or pot parts left in the hole, and mulch piled against the trunk.

How it spreads

It does not spread from plant to plant.

When

Any time; trees decline slowly over many years.

What to do, gentlest first

This is not an infection, so sprays for diseases won't help. Fix the cause below.

1. Plant at the right depth Prevent

   Dig the hole 2 to 3 times as wide as the root ball and no deeper than it (in heavy clay, about 3 inches shallower). Remove any soil sitting above the trunk flare.

2. Fix circling roots at planting Prevent

   Cut through circling roots on container plants in a few places, straighten or remove them on bare-root trees, and take out wire baskets and burlap. Cut circling roots when moving a plant up to a bigger pot, too.

3. Mulch shallow, off the trunk Prevent

   Keep mulch no deeper than about 3 inches and never against the trunk. Water young trees in dry spells and skip fast-release fertilizer.

4. Have an arborist cut girdling roots By hand

   Roots that press only lightly can be cut out. Roots that have sunk deep into the trunk are often left alone, since cutting can hurt the trunk.

   If a root squeezes more than one-third to one-half of the trunk's circumference, the tree may be unstable; have it checked for removal.

Plants it affects

Black gum (tupelo), Bradford pear (Callery pear), Eastern white pine, Flowering crabapple, Flowering dogwood, Ginkgo, Holly, Juniper, Oaks (white, red and pin oak), Red maple, Sugar maple, Thornless honeylocust