Arboriculture & Urban Forestry 34(2): March 2008 Arboriculture & Urban Forestry 2008. 34(2):129–132. 129 Serviceberry Cultivars Tested as Street Trees: Second Report Henry D. Gerhold Abstract. Through the Municipal Tree Restoration Program, cooperators planted eight serviceberry (Amelanchier spp.) cultivars in 15 communities for evaluation as street trees, typically comparing two in each community. Standardized measurements in years 1, 2, 3, 6, 9, and 12 revealed differences in trunk diameter, height, crown width, and health of foliage and branches. Among the four cultivars that have been tested most extensively, the main difference is that Cumulus and Robin Hill are much taller in the twelfth year than Tradition and Autumn Brilliance. ‘Cole’s Select’, ‘Princess Diana’, Reflection™, and Spring Glory also have been performing well for 6 to 10 years, but they have been tested at just one or two locations. Survival, growth, and health have been superior on more spacious sites, but with proper care, serviceberry cultivars can do well even along downtown streets. All eight of these cultivars are appropriate for planting under overhead wires. Key Words. Amelanchier; performance testing; serviceberry cultivars; street tree evaluation. In 1989, the Municipal Tree Restoration Program (MTRP) started evaluating serviceberry (Amelanchier spp.) cultivars as street trees. MTRP encourages municipalities to improve their tree programs through demonstration plantings of free trees and, through research, provides helpful information for selecting spe- cies and cultivars that are compatible with utility wires. A pre- vious report (Gerhold 1999) indicated the five cultivars that had been evaluated by then, Autumn Brilliance, Cumulus, ‘Prin- cess Diana’, ‘Robin Hill’, and Tradition, generally had healthy foliage and grew well. Autumn Brilliance was broader but not as tall as the others at that time and had healthier foliage. All had pleasing characteristics, and their structure was conducive to pruning, which would give clearance for pedestrians and ve- hicles. Descriptions of the cultivars being tested, and many others, appear in Dirr (1998), Gerhold et al. (2001), and Jacobson (1996). MATERIALS AND METHODS Plants and Experimental Design Cooperators planted the serviceberry cultivars during 1989 to 1999 in 14 Pennsylvania, U.S. communities (Bedford, Blairs- ville, Delaware Water Gap, Eagles Mere, Genesee, Laporte, Meadville, Orrstown, Reading, Tioga, Union City, Warren, Washington, and Williamsport) and one in Waverly, New York. Representatives of the communities chose several planting sites in each municipality with the advice of utility foresters, service foresters in the Bureau of Forestry, or Penn State extension urban foresters. Characterization of the soils was not attempted, be- cause urban soils are so highly variable that they cannot be put into a normal classification system. The experimental plots rep- resented a variety of randomly sampled site conditions within each community, enabling valid statistical comparisons between the cultivars in a community by analyzing variation between cultivars and among plots. Each test planting in a community consisted of two cultivars, except for one in Waverly, New York, which had a single cul- tivar; two others were planted there a year later. The two culti- vars in a community were alternated within each plot. The num- ber of plots in a community varied according to spaces that were available and could accommodate at least four trees. Typically there were four to ten plots that contained four to 16 trees each resulting in a total of 48 to 50 trees. All of the trees being tested were planted along streets and under electric conductors. The local utility company arranged for the removal of any large trees that interfered with utility lines, thus making space for planting in some plots. Plant Materials Eight serviceberry cultivars were tested: Autumn Brilliance, ‘Cole’s Select’, Cumulus, ‘Princess Diana’, Reflection™, ‘Robin Hill’, Spring Glory, and Tradition. The species names of these cultivars are inconsistent in the nursery trade and the literature and may include Amelanchier arborea, A. canadensis, A. laevis, and A. × grandiflora. The test trees came from several nurseries as balled and bur- lapped stock, and when nursery stock was dug, the longer roots extending beyond the root ball were severed. The same nursery always supplied the two cultivars for a community. When the trees were planted, average calipers (15 cm [6 in] above the ground) ranged from 2.6 to 4.7 cm (1.04 to 1.88 in) and average heights from 2.8 to 4.1 m (9.2 to 13.5 ft). The wide range in heights and calipers presumably could be explained by genetic differences among cultivars and cultural differences among the nurseries that supplied the trees. Measurements and Analysis Trained cooperators inspected and measured the trees soon after planting, then annually during the first 3 years, and at 3-year intervals afterward. During September or October, a service for- ester or extension urban forester, using standardized procedures, measured tree height, trunk diameter at breast height, and crown width; and classified the health of foliage, branches, and trunk separately. The health of foliage and branches was estimated ©2008 International Society of Arboriculture
March 2008
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