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


Location: Gardens Unit

2012 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:
The new Living Collections Policy was completed in June 2012. It provides for the formation of a new Plant Collections Committee that will oversee acquisitions to collections and develop targets for all USNA plant collecting activities. Controlling invasive plants continues to be a pressing issue on the grounds of the U.S. National Arboretum. Teams of ASRTs are working to combat invasives in specific zones of the USNA grounds and are conducting surveillance on cleared parcels to ensure that invasive plants are not able to reestablish. 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. Designs are nearly complete for the Springhouse Run Stream Restoration project that also includes retrofits of all but one of the stormwater inlets in the R Street parking lot. Construction is anticipated to begin sometime in 2013 on both projects. Collaboration with the U.S. Army Corps of Engineers and the District of Columbia Department of the Environment has resulted in the completion of the long-awaited pollution abatement structure at the storm sewer outfall just south of New York Avenue. The structure will remove floatable trash and hydrocarbons from the stream. In the process of completing the work it was discovered that sanitary sewage is currently discharged into the storm sewer system that feeds the stream. This condition has been reported to the District of Columbia Department of the Environment for investigation and action.

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. The Friends of the National Arboretum (FONA) worked with Gardens Unit staff to provide new plants from nursery sources in conjunction with their spring plant sale. These plants will significantly increase the holdings of cultivars in many of our collections. Efforts to increase wild-collected native plant germplasm in collections have been postponed in 2012 due to loss of funding. It is hoped that these activities can be resumed in 2013. This work will preserve genetic diversity within ornamental plants that can potentially aid in breeding and selection work.

2. Evaluation of germplasm. Staff have become more involved in propagating 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. Plants collected in the High Plains region in 2010 are being evaluated for use in green roofs. Rare conifer and azalea cultivars have been propagated to secure germplasm. This germplasm may be of benefit to plant breeders and researchers.

3. 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 have been added to the site, and gardening information is being expanded. Most of the potential in this area lies in the incorporation of interpretive signs in existing gardens and collections. 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.