224 Labrosse et al.: Effects of Tree Stabilization Systems on Tree Health Table 7. Results of comparisons of symptoms for sampled trees with and without stabilization systems, stratified by land owner- ship (Wilcoxon signed ranks test, P = 0.05; public n = 247, private n = 241). Symptom Overall health Crown dieback Girdled trunk Swelling Pest/disease Leaf scorch Wilting Stunted growth Suckering Mean values for public trees with TSS 5.00 4.86 4.83 4.99 5.00 4.66 4.97 5.00 4.99 Mean values for public trees without TSS 4.78 4.56 4.72 5.00 4.74 4.74 4.88 4.92 4.92 Public trees P value <0.0001z 0.0005z 0.1979 0.7729 <0.0001z 0.8048 <0.0001y 0.0003z 0.0408z z Significantly (P = 0.05) less severe on trees observed with a tree stabilization system. y Significantly (P = 0.05) more severe on trees observed with a tree stabilization system. Note: Trees on private land have no known warranty inspection and are maintained by private staff or contractor. Trees on public land have a warranty inspection at 24 months and removal of TSS is required. Public trees are maintained by city staff. ranty periods), indications that the TSS was on too long were sub- stantially rusted wire ties, hoses bleached from sun exposure, and loose metal stakes that were no longer tightly held in the ground. In some cases, plastic hose segments had shifted allowing the metal ties to form small indentations in the bark. The research concurs with Appleton (2006) and Brown (1987), indicating that when TSSs remain on the tree for too long, serious negative health effects can begin to develop. In fact, Brown (1987) shows in his research that damages caused by extended use of TSS may be occurring at the cellular level even if not visible noticeable to the naked eye. CONCLUSION In most cases, it was found that TSSs were associated with im- proved health during a short period (1–3 years) after transplant. However, management of TSSs affect tree damage. Trees planted on public land undergo a two-year warranty inspection where all TSS materials are removed (White, pers. comm.) and these trees were found to benefit from the use of a TSS. These trees expressed fewer symptoms of diminished overall health, crown dieback, pests/diseases, stunted growth, and suckering than trees without a TSS. Notably, they did not suffer significantly more gir- dling or swelling even though they had a TSS. Conversely, trees on private land, where management is unknown, expressed sig- nificantly poorer health for three out of four symptoms. Privately owned trees with a TSS had severe swelling and girdling on their trunks—along with more crown dieback—than trees without a TSS, vivid indications of TSSs left on the tree too long (Figure 2d). Continuing research is needed to fully understand the health effects of TSSs on tree health. Other researchers have suggested the use of photodegradable or cloth-like materials for reduc- ing girdling and swelling that might mitigate damages to trees with TSS that are not removed in a timely way (Ball et al. 1997; Appleton et al. 2008). The current research observed three TSS types, but all generally consisted of the same commonly-craft- ed tying materials (steel wire covered with garden hose seg- ments). Biodegradable materials, such as burlap ties, should be explored for their effects on tree health as well as their capac- ity to provide adequate stabilization support because biodegrad- able materials may alleviate problems of the common types ob- served here. Timely tie degradation (in the event of inadequate maintenance of tying materials) might improve tree health. ©2011 International Society of Arboriculture LITERATURE CITED Alvey, A., P.E. Wiseman, and B. Kane. 2009. Efficacy of conventional tree stabilization systems and their effect on short-term tree develop- ment. Arboriculture & Urban Forestry 35(3):157–164. Appleton, B.L. 2006. Tree stabilization at transplant. SNA Research Conference 51:473–475. Appleton, B.L., C. M. Cannella, P. E. Wiseman, and A. Alvey. 2008. Tree stabilization: current products and practices. Arboriculture & Urban Forestry 34(1):54–58. Ball, J., D. Williams, and P. Weicherding. 1997. Planting and mainte- nance of woody ornamental plants. pp. 39–61. In: J. Lloyd (Ed.). Plant Health Care for Woody Ornamentals: A Professional’s Guide to Preventing and Managing Environmental Stresses and Pests. Univer- sity of Illinois Board of Trustees and International Society of Arbori- culture, Champaign, IL. 223 pp. Bradley, G.A. (Ed.). 1995. Urban Forest Landscapes: Integrating Mul- tidisciplinary Perspectives. University of Washington Press, Seattle, WA. 224 pp. Brown, I.R. 1987. Suffering at the stake. pp. 85–90. In: D. Patch (Ed.). Advances in Practical Arboriculture. Forestry Commission Bulletin 65, HMSO, London, England. Clark, J.R., and N. Matheny. 1991. Management of mature trees. Journal of Arboriculture 17(7):173–184. Corry, R.C., and J.I. Nassauer. 2002. Managing for small-patch patterns in human-dominated landscapes: Cultural factors and Corn Belt agriculture. In: J. Liu and W. Taylor (Eds.). Integrating Landscape Ecology into Natural Resource Management. Cambridge University Press, Cambridge, Mass. pp. 92–113. Costello, L.R., E.J. Perry, N.P. Matheny, M.J. Henry, and P.M. Geisel. 2003. Abiotic Disorders of Landscape Plants: A Diagnostic Guide. University of California Agriculture and Natural Resources, Oakland, CA. 242 pp. Eckstein, R., and E.F. Gilman. 2008. Evaluation of landscape tree sta- bilization systems. Arboriculture & Urban Forestry 34(4):216–221. Gilman, E.F. 1997. Trees for Urban and Suburban Landscapes. Delmar Publishers, Albany, NY. 662 pp. Glenn, E.M. 1965. A trial of tree ties. East Malling Research Station Annual Report 1964. pp. 200–202. Harris, R.J., and N.L. Bassuk. 1993. Tree planting fundamentals. Journal of Arboriculture 19(2):64–70. Mean values for private trees with TSS 4.94 4.57 4.30 4.45 4.99 4.80 5.00 4.99 4.72 Mean values for private trees without TSS 4.93 4.82 4.78 4.98 4.64 4.84 5.00 4.96 4.82 Private trees P value 0.8855 0.0259y 0.0026y <0.0001y 0.0004z 0.1781 1.0000 0.8003 0.5754
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