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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Gardens Unit » Research » Research Project #418110


Location: Gardens Unit

2010 Annual Report

1a. Objectives (from AD-416)
The nursery and landscape maintenance industry is the most important segment of agriculture in many areas. Nursery crops provide high-value alternatives to field crops where land prices require a high return. There is increasing interest in the aesthetic and economic value of landscapes that increase quality of life and property values. There is a need to increase the diversity of plant materials in landscapes to realize their full environmental benefit. The nursery industry must continue to offer new and improved ornamental plants to retain economic viability. The landscape maintenance industry must offer clientele services that provide better environmental stewardship. Objective 1: Expand, establish, maintain, trial, document, and interpret living collections of woody and herbaceous landscape ornamentals with high aesthetic, scientific, and educational value, and that reflect current relevant ARS horticultural research programs as appropriate; Objective 2: Incorporate optimal environmentally-sound horticultural practices that increase overall garden management efficiency, and develop integrated pest management strategies and technologies for ornamental plants, especially those suited to the environment of the national capital; Objective 3: Disseminate scientific and practical information to floral and nursery crop industries, public gardens, the increasing number of visitors to the U.S. National Arboretum and its web site, and the general public interested in gardening; Objective 4: Distribute to and exchange with the horticulture industry and collections new and unusual landscape plants.

1b. Approach (from AD-416)
A unified Collections Policy will be developed to provide a framework for identifying the objectives of each plant collection and display garden on the campus of the USNA. Existing collections will then need to be evaluated against this collection policy and a multi-year Plant Acquisition Plan will be developed for each collection to guide development. New ornamental plants will be procured from industry leaders in ornamental plant introduction efforts. Existing Glenn Dale azaleas in the holdings of the Azalea Collection will be propagated and used to replace Glenn Dale azaleas of unknown identity. Native flora will be collected. The Flowering Tree Collection, Holly Magnolia Collection, Conifer Collection and collections of penjing in the National Bonsai and Penjing Museum will be augmented by incorporating a wider variety of plants. The current Power Plants exhibit site will be used to highlight ARS accomplishments. Staff will continue to utilize IPM in management of their collections and will incorporate other technologies such as solar power, green roofs, rain gardens, and water wise gardens as funds allow. Program ideas will be developed in collaboration with the Educational Programs Coordinator. Plants with superior landscape attributes within existing collections will be propagated for distribution and evaluation in collaboration with Floral and Nursery Plant Research Unit efforts.

3. Progress Report
Draft of Collections Policy Work was completed on the initial draft of the Collections Policy for the gardens and collections managed by the Gardens Unit. When review is completed and refinements are made, it will serve as a guidepost to future development and retrenchment. Distribution of Plants for Evaluation Plants of bay, Laurus nobilis, and Japanese yew pine, Podocarpus macrophyllus, were propagated and widely distributed for evaluation by nurseries and public gardens. The main emphasis of this work is to determine the hardiness of these plants. Invasive Species Target Species and Locations Developed A comprehensive of list of targeted invasive plants and areas on the grounds where they are growing was drafted to prepare for any end of year funds that might be available for contracting for removal of invasive plants. Domestic Collections of Wild Germplasm Several trips in the Piedmont region and in the Northern High Plains and Black Hills region were completed to expand holdings of native germplasm, including drought tolerant provenance of tree and shrub species and drought tolerant native plants with potential for use in green roof plantings. Completion of Irrigation Systems Remaining funds earmarked for irrigation modernization were expended in completion of automated systems for the Azalea Collection, The Fern Valley Native Plant Collection, and the National Bonsai and Penjing Museum and Test Plot area. The completion of these systems has resulted in more efficient use of water for irrigation.

4. Accomplishments
1. Germplasm acquisition, distribution, and incorporation into collections. A major objective of the Gardens Unit is to enrich the living plant display collections at the U.S. National Arboretum by incorporating documented germplasm into these areas. 530 plants were accessioned and 1171 plants have been added to the U.S. National Arboretum plant records database in Fiscal Year 2010. A new initiative was undertaken to collect plants in the Black Hills region of the United Sates and surrounding regions of the High Plains to assemble germplasm potentially useful in developing trees and shrubs with enhanced heat and drought tolerance and short stature for planting under overhead utility lines. Herbaceous taxa potentially useful in green roof culture were also collected. This germplasm will benefit the nursery trade as the need to develop landscape plants better able to withstand climate change becomes more urgent.

2. Evaluation of germplasm. Financial support from the Friends of the National Arboretum has allowed for the hire of a plant propagator to support the increase of plants in preparation for distribution and evaluation and to protect germplasm holdings that may have diminished due to attrition. Several potential introductions have been propagated, and two have been sent out for evaluation. This germplasm will benefit the nursery trade by expanding their product line. Rare conifer and azalea cultivars have been propagated to secure germplasm. This germplasm may be of benefit to plant breeders and researchers.

3. Ornamental Edibles exhibit. The U.S. National Arboretum can be used as a vehicle for ARS outreach efforts. The clearest current trend in gardening is the increasing popularity of fruits and vegetables. While it may seem that this might be tied to the economic downturn, survey data reveals that the driving factor is most likely the desire for a greater diversity of fresh produce with unique flavor and appearance. The small garden in the entrance of the National Herb Garden was renovated and transformed into an Ornamental Edibles Exhibit featuring food plants with outstanding ornamental value grown in spring, summer, and fall rotations. This Ornamental Edibles exhibit showed visitors that they can produce vegetables in an ornamental garden without compromising aesthetic value of the landscape. This will result in gardeners growing a greater diversity of cultivars and crops in their landscapes.

4. Dissemination of plant information to the public. The nearly half a million visitors to the gardens and collections of the U.S. National Arboretum could potentially learn about the work of ARS. The Gardens Unit provides major input in increasing the quality and quantity of information on the Arboretum web site, and the web site now serves five million visitors annually. Many nursery firms and gardening sites are linking to our web site. Strong ties to the nursery industry have been established in the creation of the Introduction Garden. Virtual tours and a blog are being added to the site, and gardening information is being expanded. This work helps to create well informed garden product consumers and increase interest in landscape plants to help maintain a strong domestic nursery production industry.

5. Management of invasive plants. Controlling invasive plants continues to be a pressing issue on the grounds of the U.S. National Arboretum. Another 50 acres were treated to eliminate current infestations of invasive plants in FY 2010. A complete listing of the invasive species present on various tracts on the grounds of the U.S. National Arboretum was developed to aid future efforts to manage the problem. This work helps to preserve existing germplasm in the gardens and collections of the USNA, protects woodland and meadow habitats on the grounds from degradation, and provides a model for management of invasive plants that may be useful for other land managers.