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Jane Hodgins


Web Resource: Submit a "survivor" elm

U.S. Forest Service, Northern Research Station, Launches Website for Reporting American Elm

DELAWARE, OH, March 29, 2011 - The U.S. Forest Service, Northern Research Station has launched an on-line system for reporting the location of American elm tree “survivors,” or trees that can potentially tolerate Dutch Elm Disease (DED). In its first few weeks, individuals in five states used the reporting site to identify the locations of more than 40 trees.

The on-line system can be found at:

“Survivor” American elm trees are key to re-establishing the elm in forests, floodplains and city boulevards, and survivors are rare. More than 100,000 American elm trees have been tested for resistance to Dutch elm disease. None were found to be resistant to DED; however, eight trees exhibited enough tolerance to the disease to survive exposure. Tolerant trees exposed to the fungus show disease symptoms the year of inoculation but no symptoms the next year.

Identifying additional DED-tolerant American elm trees across the species’ natural range would allow researchers to create a genetically diverse elm seed plantation that would produce seed to establish DED-tolerant elm trees in areas where the trees could naturally regenerate and spread. The process of regeneration would allow the American elm to co-evolve with the DED fungal pathogen, which would improve the chances that trees could generate tolerance mechanisms to new forms of the fungus.

Northern Research Station researchers Jim Slavicek and Kathleen Knight have heard many reports of big elm trees, but these reports have been light on directions. “People are always happy to report seeing an American elm,” Knight said. “When they see a big elm, they remember it, but they don’t always remember the location well enough to share their discovery.”

Technology is filling that gap. Knight and Slavicek worked with Jim Lootens, an information technology specialist with the Northern Research Station, to develop a web-based system that allows users to quickly and accurately pinpoint the location of a big elm using Google Maps. Information entered by users populates a database that Slavicek and Knight use to prioritize elm sightings based on location, habitat and tree size. The system also generates a map that shows Slavicek and Knight the locations of all of the elms reported.

Users identify the general location by entering an address, zip code, latitude and longitude, or even a place name, such as the name of a forest, park or wildlife refuge. Google Maps shows the area, and from there users can zoom in using either map view or satellite view until they can pinpoint a tree’s location and mark the spot with a digital “thumbtack.”  

Once the location has been identified, site visitors are asked to describe the tree itself – how big is it, is it healthy or showing symptoms of Dutch Elm Disease, and what kind of habitat surrounds it. Slavicek and Knight are looking for American elm trees that are 24 inches or greater in diameter at breast height (about 4.5 feet), and that show no signs of DED. Only big trees are old enough to have been exposed to DED and can be considered “survivor” American elms, according to Knight.

Site visitors are also asked for the name and contact information for the landowner. Ultimately, Slavicek and Knight want to visit locations reported through the website and collect a branch to propagate in a nursery. Once big enough, the tree will be injected with DED to determine whether it really is disease tolerant and, if so, it will be cross-pollinated with healthy American elms and the seedlings will be used in forest restoration.

Just three weeks into the website’s use, Slavicek and Knight said the site is exceeding their expectations as a tool for identifying “survivor” American elms.

“This allows foresters, park managers, master gardeners and anyone who can accurately identify an American elm to contribute to research that could help re-establish this tree species” Slavicek said. “This is a case where technology is helping us turn back the clock for the American elm.”

The DED fungal pathogen Ophiostoma ulmi was introduced into the United States in 1930 and destroyed millions of American elm trees in the United States and Canada. By 1976, only 34 million of the estimated 77 million elms present in the urban landscape before introduction of the DED pathogen remained, and far fewer are still present today. The tree’s native range extends from the East Coast to North Dakota and as far south as Texas and northern Florida.

The mission of the U.S. Forest Service is to sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations. The agency manages 193 million acres of public land, provides assistance to state and private landowners, and maintains the largest forestry research organization in the world. The mission of the Forest Service’s Northern Research Station is to improve people’s lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.