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


Location: Gardens Unit

2014 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 Gardens Unit is leading the development of a new initiative to engage the public and green industry professionals featuring turfgrass, the science of turfgrass development and maintenance, and human interaction with grasses, including grain crops. The centerpiece of this effort is the Grass Roots exhibit, a one-acre display of turf in various applications, ornamental grasses, and grain crops. 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 of both projects is anticipated to begin in FY 15. The azaleas growing on the Glenn Dale Hillside section of the Azalea Collection suffered from decades of damage from invasive vines, heavy snow, and lack of light from the growth of a thick stand of sapling trees. A landscape maintenance firm was contracted to remove excess trees and invasive plants and to provide renewal pruning for the azaleas. This has greatly increased the health of the azaleas and simplified maintenance tasks. Germplasm acquisition is now governed by the new Living Collections Policy. There is a renewed effort to increase the scientific quality of collections by limiting acquisitions to originating nursery sources and plants collected in the wild. Collection activities resumed in 2014 after suspension caused by lack of travel funding. The main focus on collection activities has been to assemble germplasm that will be used in the Springhouse Run Stream Restoration project. Plants collected in the High Plains region in 2010 are being evaluated for use in green roofs. This germplasm may be of benefit to plant breeders and researchers. Cooperator evaluation led to the introduction of ‘Petite Jade’ Japanese laurel. Controlling invasive plants continues to be a pressing issue on the grounds of the U.S. National Arboretum. 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.

4. Accomplishments