P&PDL Picture of the Week for
January 23, 2006

Stem Girdling Roots

Karen Rane, Plant Disease Diagnostician, Department of Botany & Plant Pathology, Purdue University

Dieback and decline in landscape trees is a complex phenomenon, involving many cultural and environmental factors. When evaluating trees for stress factors, check the base or the tree for roots that appear to be “strangling” the lower trunk (Figure 1).  These roots are called stem girdling roots, and are often associated with tree decline. 

Poor planting techniques are believed to initiate the development of girdling roots.  Planting bare-root trees in holes that are too small for the root system, planting trees too deeply, and planting pot-bound containerized trees without spreading out or cutting the root ball, can cause major roots to grow in a circular pattern close to the trunk.  Over time, both the trunk and the roots increase in diameter, resulting in compression of the lower trunk and disruption of water and nutrient transport.  Such areas can become structurally weak as well, and trees with girdling roots may fall in windstorms.  Look for trees that have no natural taper to the trunk at the soil line (especially on one side of the trunk) as a possible indication of a girdling root.   Enlargement of the trunk near the girdling root may also occur.  If the tree is planted too deeply, the girdling root may be on the portion of the trunk under the soil surface.

The best way to manage girdling root problems is to avoid them by using proper planting techniques.  In some cases, a girdling root on a younger tree may be cut and removed before extensive trunk damage occurs.  Removal of girdling roots may cause extensive damage to older trees, however.  For more information on stem girdling roots, check out the excellent article “A Practitioner’s Guide to Stem Girdling Roots of Trees” by Gary R. Johnson of the University of Minnesota and Richard J. Hauer of the Minnesota Department of Agriculture.

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stem girdling root

Figure 1

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service