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Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Believed to be originally native to Asia, the disease was accidentally introduced into America, Europe, and New Zealand. In these regions it has devastated native populations of elms that did not have resistance to ...
The American elm cultivar Ulmus americana 'American Liberty' is in fact a group of six genetically distinct cultivars under a single name, although they are superficially similar. [1] The Liberty elm is reportedly suitable for street planting, being tolerant of de-icing salts and air pollution.
The American elm is a deciduous tree which, under ideal conditions, can grow to heights of 21 to 35 meters (69 to 115 feet). [3] The trunk may have a diameter at breast height (dbh) of more than 1.2 m (4 ft), supporting a high, spreading umbrella-like canopy.
Dutch elm disease originated in Europe in the early 1900s. [4] Elm trees were once an ecologically valuable tree that dominated mixed broadleaf forests, floodplains, and low areas near rivers and streams. [5] They were planted in urban settings because of their aesthetic appeal and their ability to provide shade due to their V like shape. [6]
The Logan Elm that stood near Circleville in Pickaway County, Ohio, was one of the largest American elm trees (Ulmus americana) recorded. The 65-foot-tall (20 m) tree had a trunk circumference of 24 feet (7.3 m) and a crown spread of 180 feet (55 m). [1] Weakened by Dutch elm disease, the tree died from storm damage in 1964. [1]
The American Elm cultivar Ulmus americana 'Delaware' was originally selected (as tree number 218, a c.1940 seedling from North Dakota) from 35,000 seedlings inoculated with the Dutch elm disease fungus in USDA trials at Morristown, New Jersey. [1]
The American Elm cultivar Ulmus americana 'Markham' was cloned in Avon, New York before 1950 from "an outstanding tree", now long dead, growing naturally on what from 1794 was the Markham estate two miles north of Avon. [1] [2]
Rows of American elm trees line a path south of the Lincoln Memorial Reflecting Pool on the National Mall in Washington, DC (November 11, 2006) Several rows of American elm trees that the National Park Service (NPS) first planted during the 1930s line much of the 1.9-mile-length (3 km) of the National Mall in Washington, DC. DED first appeared ...