Landscape - Girdling Roods

We often see girdling roots in woody plants and this can lead to plant decline. The following is an article on the subject.

Encircling roots due to production methods, poor soil conditions, excessive mulch and narrow planting sites have contributed in one form or another to the problem of girdling. A distinction is sometimes made between two forms of girdling roots. "Girdling roots" refers to the condition that occurs when roots encircle upon themselves. Stem-girdling roots encircle the tree stem above the trunk/root collar. Both of these conditions affect the structural stability and anchoring of the plant and restrict the roots system's ability to adequately mine the soils. Stem-girdling roots compress the conductive tissue in the trunk, restricting translocation and eventually leading to trunk decay. Each situation causes a slow but progressive decline in plant performance. Treatment for girdling and stem-girdling roots consists of the selective removal of root sections. The extent of the removal varies with the condition and the length of time that the plant has been in place. Root removal may span several seasons to minimize stress to the plant. To eliminate or reduce the incidence of this problem, use proper planting procedure and long-term mulching practices. At planting, encircling roots should be cut or removed to ensure proper movement of new and existing roots into the surrounding soils. Excessive mulch layers around the bases of plants cause new roots to work their way upward to capitalize on optimal aeration, moisture and nutrient levels. Roots remain in the mulch layers and encircle as continued mulching maintains the preferred environment. Mulch layers should be removed periodically and problem roots cut and redirected.

Girdling roots (excavated and painted white) on declining Linden tree. Photo by Linda Haugen, USDA Forest Service, Bugwood.org.

Girdling roots on maple. Photo by Linda Haugen, USDA Forest Service, Bugwood.org.

Information from a section of "Abiotic Plant Disorders - Symptoms, Signs and Solutions A Diagnostic Guide to Problem Solving" by Robert E. Schutzki and Bert Cregg, Departments of Horticulture and Forestry, Michigan State University Michigan State University. Go to http://www.ipm.msu.edu/cat08land/pdf/9-19abiotic.pdf for the full factsheet with photos.