Finding the next All-American
Although, researchers have not identified an American elm that can take the place of the American elms that once graced our neighborhoods and highways, they are still working on it. One possibility may come from the “Jefferson American elm.” The original tree is one of very few survivors planted on the National Mall, Washington, D.C. in the 1930s.
Researchers from the Agricultural Research Service and the National Park Service took cuttings of surviving trees, grew them in their nurseries and are monitoring their performance. The Jefferson American elm, which grows to 65 feet tall with a vase shape and stronger branch unions, looks the most promising. In another effort, researchers with the Environmental Science and Forestry Department at State University of New York are attempting to transplant antimicrobial proteins into new American elm trees. These particular proteins enhance a tree's resistance to fungus. The gene from the protein is transferred into a soil bacterium that is able to transfer some of its DNA into the elm tissue, which is grown in tissue culture then planted in the research greenhouse. Researchers then perform regular testing for Dutch elm disease.
If successful, genetic engineering may come to the landscape. Many elm hybrids are being developed as substitutes for the American elm. Some of them are showing promise for resistance to Dutch elm disease, but they trade off other inadequacies, such as susceptibility to elm leaf beetles and elm yellows. Some are also not as cold hardy as the American elm.
We won't know the full extent of the hardiness of these elms until they are planted out into the landscape and studied. Your assistance with the research can be helpful. Plant one or many of the new hybrids in an area that won't suffer if the tree fails. ‘Frontier,’ ‘Patriot,’ ‘Prospector,’ are a few of the hybrids or new cultivars available.
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