180 Gerhold: Crabapple Cultivars As Street Trees ratings below 4.0, in ascending order, were given to Ameri- can Masterpiece (one location), American Triumph™ (one location), Velvet Pillar™, ‘Snowdrift’, Royal Scepter™(one location), Brandywine, and Madonna. However, even these only had injuries to less than half of their foliage at the end of the growing season. None of the cultivars had serious health problems with their branches. Trunk injuries were caused mainly by mowers and vehicles, seldom serious, and not associated with cultivars; therefore, they are not reported. Several kinds of injuries and other problems were ob- served. Foliage injuries were caused variously by apple scab (Venturia inaequalis), Japanese beetle (Popillia japonica), fall webworm (Hyphantria cunea), and gypsy moth (Lyman- tria dispar); cultivar differences in one or more of these are reflected in the foliage health ratings. Basal sprouting, which is unsightly if not removed by pruning, occurred in many of the cultivars, perhaps all; sprouting was not routinely re- corded. A more serious need for pruning occurred where the lower branches of the shorter and broader cultivars planted close to streets or sidewalks interfered with pedestrians, ve- hicles, and visibility. The fruit of some cultivars was messy when it fell on sidewalks and could be treacherous to pedes- trians, especially that of Brandywine, which was 1 in or more in diameter. However, most cultivars had attractive fruit 1 ⁄4 to 3 ⁄8 into the winter; fruit of Madonna, however, quickly lost its color. Extensive evaluations of crabapple cultivars for disease resistance and aesthetic qualities in Ohio (Chatfield et al. 1999, 2002), and at 25 locations in the national crabapple evaluation program (Green 1994; Den Boer and Green 1995) were not entirely consistent with each other nor with the evaluations in Pennsylvania. In fact, some cultivars that were dropped from the Ohio program—‘Adams’, Centurion, ‘Red Barron’, and Velvet Pillar—performed quite well un- der our street-side conditions. It is apparent that disease re- sistance varies among years and geographic regions and also with local site conditions. Aesthetic criteria and desirability of form and branching characteristics undoubtedly differed among the various studies too. CONCLUSIONS Most of the cultivars that were evaluated as street trees have proven to be very successful with attractive flowers, fruit, and healthy foliage. Even the tallest ones are compatible with overhead wires and will require little or no pruning for clear- ance. Pruning will be needed to remove basal sprouts and lower branches as trees grow, particularly branches that in- terfere with pedestrians, vehicles, and visibility for safety. Recommended cultivars, limited to those evaluated at three or more locations, include ‘Adams’, American Salute™, Cen- turion, ‘Donald Wyman’, Harvest Gold, ‘Red Barron’, Red ©2007 International Society of Arboriculture in in diameter, which in some cases persisted well Jewel, ‘Sentinel’, ‘Snowdrift’, ‘Spring Snow’, and ‘Sugar Tyme’. Others that appear promising include American Master- piece, American Spirit™, American Triumph™, ‘Beverly’, Holiday Gold, ‘Prairifire’, zumi ‘Calocarpa’, and perhaps Royal Scepter™ and Velvet Pillar™ if foliage health proves to be adequate. When any of these crabapples are selected for particular sites, their size, growth rate, and branching habit should be considered in relation to space limitations along with attrac- tive features such as flowers and fruit. There are many useful references that provide more complete information about cul- tivar characteristics, including Michael (1990), Green (1994), Chatfield et al. (1999), Dirr (1998), Gerhold et al. (2001), and Gerhold (2005). Acknowledgments. Financial support for the Municipal Tree Res- toration Program was provided by Allegheny Energy, Asplundh Tree Expert Company, Baltimore Gas & Electric Company, Bartlett Tree Expert Company, Duquesne Light Company, First Energy Company, Hazlett Tree Service, PECO Energy Company, PPL Elec- tric Utilities, and UGI Utilities. Foresters of the Pennsylvania Bu- reau of Forestry and Extension Urban Foresters of Penn State Uni- versity assisted with community liaison and tree measurements. LITERATURE CITED Chatfield, J.A., E.A. Draper, K.D. Cochran, P.W. Bristol, and D.E. Allen. 1999. Comprehensive aesthetic evaluations of crabapples at Secrest Arboretum in Wooster: 1993–1998. Ohio State University, Ohio Agricultural Research and Development Center, Special Circular 165–99. Chatfield, J.A., E.A. Draper, D.A. Herms, and K.D. Cochran. 2002. Apple scab on crabapples at the Secrest Arboretum: 2001. Ohio State University, Ohio Agricultural Research and Development Center, Special Circular 186–02. Den Boer, J.H., and T.L. Green. 1995. Disease and aesthetic ratings. Malus. International Ornamental Crabapple Bul- letin 9:8–56. Dirr, M.A. 1998. Manual of Woody Landscape Plants. Stipes Publishing, Champaign, IL. 1187 pp. Gerhold, H.D. 2000. Crabapple cultivars tested as street trees: Second report. Journal of Arboriculture 26:48–59. ———. 2005. Landscape Tree Factsheets CD. School of For- est Resources, University Park, PA. Gerhold, H.D., N.L. Lacasse, and W.N. Wandell. 2001. Landscape Tree Factsheets. College of Agricultural Sci- ences, University Park, PA. 456 pp. Gerhold, H.D., H.L. McElroy, and H.L.H. Rhodes. 1994. Street tree performance tests of crabapple cultivars: Initial results. Journal of Arboriculture 20:87–93. Green, T.L. 1994. Results of the national crabapple evalua- tion program. Proceedings of the Metropolitan Tree Im- provement Alliance 8:1–8.
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