Potential of Alternative Tsuga spp. as Landscape Replacements for T. canadensis: Longer-Term Evaluation and Propagation of T. chinensis.
Richard W. Harper and Paul A. Weston
Abstract: Seven species of hemlock (Tsuga spp.)—four from North America and three from Asia—were evaluated in replicated plots in Katonah, New York, United States (USDA Plant Hardiness Zone 6b) as potential replacements for eastern hemlock (Tsuga canadensis), which is gradually being extirpated from landscapes in the eastern United States. by the invasive hemlock woolly adelgid (Adelges tsugae). Trends reported in an earlier study (Weston and Harper 2009) continued but were exaggerated after an additional three years of observation. For example, Chinese hemlock (T. chinensis) continued to show the greatest potential as a replacement for T. canadensis as mortality was very low, overall plant health was exceptional, and tolerance to A. tsugae was robust. Early indicators suggest that T. chinensis may also be readily propagated from hardwood cuttings under appropriate greenhouse conditions. These characteristics suggest that T. chinensis may indeed become a viable replacement for T. canadensis, and a valuable addition to landscapes in the eastern U.S.
Keywords: Elongate Hemlock Scale; Hemlock; Hemlock Woolly Adelgid; Host Resistance; Tsuga canadensis; Tsuga caroliniana; Tsuga chinensis; Tsuga diversifolia; Tsuga heterophylla; Tsuga mertensiana; Tsuga sieboldii.