2007 Annual Report 1a.Objectives (from AD-416) To evaluate existing superior U.S. National Arboretum tree and shrub introductions and selections for suitability as street trees and for planting under utility lines, and to initiate a program for the breeding, selection, and evaluation of superior trees and shrubs for street and utility line plantings. To promote the use and benefits of planting appropriate trees in utility right-of-ways to reduce costs of tree trimming, removal and replacement, and minimize power outages caused by interference between oversized trees and utility lines. 1b.Approach (from AD-416) Existing U.S. National Arboretum introductions and selections will be evaluated for growth characteristics in a pot-in-pot production system in comparison to a traditional in-ground production system. Canopy structure, caliper and height gain, and root structure will be compared by destructive sampling. Remaining trees will be grown to suitable size for transplanting to city streets for on-going evaluation of growth and resistance to the stresses of urban street sites. 3.Progress Report Street and utility-line tree breeding This report documents research conducted under a Reimbursable Agreement between ARS and the Western Maryland Resource Conservation and Development Council to evaluate and develop urban-tolerant trees for utility line plantings. Additional results of the research can be found in the report for the related in-house project 1230-21000-043-00D, "Genetic Improvement of Landscape Trees for Superior Pest Resistance." Further work was conducted to evaluate selected U.S. National Arboretum tree cultivars for suitability in street and utility line planting situations. Trees were grown either in pot-in-pot or traditional in-ground production methods and transplanted to utility line sites in Greenbelt, MD, in addition to previous plantings in Washington, DC for on-going evaluation for suitability in street and utility line plantings. An existing problem planting where inappropriate trees were already conflicting with utility lines was remedied with appropriate tree species as a demonstration site for proper utility line tree plantings. Interpretative signage was designed and installed at demonstration sites and research areas. A web site is being developed to make information on appropriate trees for street and utility line plantings available to nurserymen, city planners, urban foresters, and homeowners. New germplasm was acquired from European and domestic nurseries for integrating into the small tree breeding program at the U.S. National Arboretum. This work was carried out in collaboration with partners including the U.S. Forest Service Mid-Atlantic Center for Urban and Community Forestry, the University of Maryland, the State of Maryland Department of Natural Resources, the Maryland Electric Reliability Tree Trimming Council, and the District of Columbia Urban Forestry Administration. This project is being monitored by email, site visits and phone calls. This research is part of Component II of National Program 301 (Genome characterization and genetic improvement); and is under ARS Strategic Plan Goal 1, Performance measure 1.2.8 and Goal 3, Performance measure 3.2.4.