There are an estimated 8 billion ash (Fraxinus) trees in North America. These species are of great value in managed landscapes (street and park trees and windbreaks), for their wood products (lumber, tool handles, baseball bats, baskets, etc.), and in natural forest ecosystems. An introduced pest from northeastern Asia, the Emerald Ash Borer (EAB), Agrilus planipennis Fairmaire, is killing all native Fraxinus in Michigan, Indiana, and Ohio, and now spreading into surrounding states and Canadian provinces. So far, tens of millions of trees have died at great economic and ecological cost. Based on ongoing evaluations, no native North American populations are yet known to be resistant to EAB. The loss of these ash species has cultural, ecological, and economic implications that warrant preserving the genetic resources before too much is lost to the insect.
Trees, as do all plants, must be adapted to their environment to thrive. Over the centuries, natural ash populations have adapted to their environments, and preserving a significant number of these populations is required for successful reintroduction of ash once adequate control measures for EAB are developed or ash trees resistant to the insect are developed. Breeding resistant ash trees for reintroduction will ultimately require an array of adapted parental populations. Given the projected degree of EAB destruction to native stands, only adequate ex situ germplasm collections protected from EAB will be able to provide this needed material. When seed quantities and quality are sufficient, ash accessions curated in the NPGS active collection at the North Central Regional Plant Introduction Station in Ames, Iowa are freely available to support the scientific research and educational efforts that will be needed to overcome EAB.
In northeastern Asia, EAB has coevolved with a different set of Fraxinus species than are native to North America. In order to give access to potential sources of EAB tolerance or resistance to researchers, it is also important to assemble, conserve, and evaluate Asian ash germplasm.
Through a collaborative process involving USDA-ARS, the Forest Service1 (USDA-FS), the Natural Resources Conservation Services2 (USDA-NRCS), the Seeds of Success3 program, Canadian Forest Service4 (CFS), tribal governments, state agencies, and many other partners, a systematic plan† is being organized to conserve the range of genetically diverse ecotypes of North American Fraxinus currently represented in nature. We recognize that these efforts will require the involvement of many parties, including land-management agencies to be effective and are working to that end. Efforts are also underway in collaboration with the Morton Arboretum and the Beijing Botanic Garden to sample and obtain diverse populations of Fraxinus in China.
A list of collectors and their contact information, organized by state, is provided at the Contacts page.
It is our goal to create a comprehensive collection of Fraxinus populations within the US National Plant Germplasm System and to ensure that these collections are representative, well-documented, properly conserved, and made available to support research on Fraxinus, EAB and other pests and pathogens, to keep options open for the development of resistant ash trees and eventual restoration of ash to American forests and managed landscapes.
†Dr. Mark Widrlechner, who heads up this project from the NCRPIS, and his assistant, Jeff Carstens, presented this plan at the 20th USDA Interagency Research Forum on Invasive Species in Annapolis, MD, January 15, 2009. This slide presentation is entitled, "Developing a Coordinated Plan for Ash (Fraxinus) Seed Collection in North America." A more recent status report, entitled "Building A Comprehensive Collection of Ash Germplasm," was presented in June, 2010 to the 4th Global Botanic Gardens Congress in Dublin, Ireland. The slide presentation and paper are available here:
1Forest Service http://www.nsl.fs.fed.us/GeneticConservation_Ash.html
2Natural Resources Conservation Service http://www.mi.nrcs.usda.gov/programs/pmc.html
3Seeds of Success http://www.nps.gov/plants/sos/
4Canadian Forest Service http://cfs.nrcan.gc.ca/subsite/seedcentre/ashconservation
The ash collection at the North Central Regional Plant Introduction Station in Ames, Iowa, currently consists of 263 accessions from 21 countries. For more details about the North American collections, please consult our maps. From within the United States, there are 176 accessions collected from 24 states. Accessions collected in the United States in recent years (134 accessions) have received special processing. The seeds in each accession are collected from several trees. Aliquots are taken from each tree — the sample size of the aliquots are determined by the tree sample with the least amount of seeds. The aliquots are combined from each tree and represent a 'balanced sample.' This balanced sample is what is used for distribution to cooperators and for back up at the National Center for Genetic Resources Preservation (NCGRP) in Fort Collins, Colorado. After balanced bulks are created, seeds from individual mother trees are retained as separate seed lots, which are useful for genetic studies requiring half-sib family structure.
The pictures below show the collecting and sampling process, as well as the storage conditions at NCRPIS.
This part of the website is currently under construction. We plan to expand it as more details about upcoming collections become available. If you would like to share information about local collection plans for the coming field season, please email Mark Widrlechner.
The following trips are being planned for 2010:
The EAB beetle is about 10 mm long by 4 mm wide. The adults lay eggs in the crevices of ash tree bark in late May to mid-June. The eggs hatch and the larvae bore under the bark and consumes the cambium of the trees while going through several larval stages. Their random boring pattern cuts across the xylem and phloem of the cambium layer, thus cutting off the transport of water and nutrients which kills the trees. The larva overwinter and then pupate in the spring. Adults emerge from May to July from D-shaped exit holes, with peak emergence in mid-June. The life cycle of the EAB is usually one year, but can be two years in colder climates.
For more information, visit the emerald ash borer information website.
