Stem girdling roots (SGRs) are roots that grow around the trunk of a tree and begin to constrict its vascular function. Xylem and phloem are restricted, preventing water, nutrients and carbohydrates from moving through the tree. SGRs can kill trees, but it is a gradual process as the trunk grows into an existing root as it ages and develops. SGRs can be easily identified by inspecting the base of a tree for a root that is wrapped around it, or if a tree is lacking a distinct root flare on one side it might be evidence that a girdling root is present just below the surface.
This issue is commonly caused by growing trees in traditional plastic containers that can encourage circular roots to develop in the pot. If these roots are not reoriented or sheared upon planting, they will remain wrapped around the tree and the trunk will eventually become strangled by its own roots as it grows. Numerous species can develop SGRs, but it is seen mostly in popular nursery selections because they are largely grown using traditional plastic containers. Some nurseries are moving to growing trees in fabric, copper-treated or air-pruning containers that can minimize the formation of circular roots prior to planting. Studies have shown that these newer containers can aid tree establishment when compared to traditional plastic containers (O’Connor et al., 2018).
Ways to minimize the occurrence of SGRs revolve primarily around proper planting. It is important to plant trees at the correct depth to ensure the root flare is present, and the planting hole should be wide enough for roots to be reoriented and stretched to prevent them from encircling the tree. SGRs can be removed if they aren’t tightly constricting the stem using pruners or a saw. If a root is heavily compressing a tree, working with a certified arborist can help determine if the root can be removed without damaging or impacting the tree’s foundation. In severe cases, complete removal of a tree may be required. You don’t want to waste time and money establishing new trees on your course only to have them fall victim to this issue.
If you have any questions about tree management on the golf course, please reach out to your regional USGA agronomist.
Reference
O’Connor, A.S., Klett, J.E., & Koski, A.J. (2018). Container type affects root development of Chanticleer Pear (Pyrus calleryana ‘Glen’s Form’) during landscape establishment. Arboriculture & Urban Forestry, 44(4), 165-173. https://files.constantcontact.com/e3923a22101/7f2cfba3-6db4-4af9-8f07-7266029d89e2.pdf
Central Region Agronomists:
Zach Nicoludis, regional director, Central Region – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org