Formation of Girdling Roots

Root crowns of 60 Norway maples, 15 sugar maples, 15 red maples, 10 green ash, 10 honeylocust, and 10 littleleaf lindens were excavated 3-10 years after planting in order to study girdling roots. Girdling roots and potentially girdling roots were more common on maple species. The majority of the girdling roots were either small or new laterals initiated during the first year after transplanting. Lateral roots at perpendicular angles, close to the base of the trunk, are often naturally positioned to develop into girdling roots. Growth of the lateral roots, which is often slow while the root terminal is intact, is stimulated when the terminal is severed as the tree is dug from the nursery. Girdling roots were not related to plantting depth. Only Norway maples frequently had severely girdling roots as mature trees. Mature sugar and red maples had few girdling roots.