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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.
The American Elm cultivar Ulmus americana 'Valley Forge' was raised by the Agricultural Research Service in Maryland. The tree was released to wholesale nurseries without patent restrictions by the U. S. National Arboretum in 1995 after proving to have a high resistance to Dutch elm disease. 'Valley Forge' proved only moderately successful in ...
Trials with the American elm have been successful; in a six-year experiment with the American elm in Denver, CO, annual Dutch elm disease losses declined significantly after the first year from 7 percent to between 0.4 and 0.6 percent; [48] a greater and more rapid reduction in disease incidence than the accompanying tree sanitation and plant ...
Testing in laboratory conditions by the United States Department of Agriculture from 1992 to 1993 revealed that 'Princeton' had some resistance to Dutch elm disease (DED), [6] [7] [8] although the original Princeton elm, which grew in Princeton Cemetery and was estimated to be over 150 years old, was felled in April 2005 after suffering 60 percent dieback, attributed by some accounts to Dutch ...
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 elm stood near the Senate wing of the Capitol building until 1948. [48] The Logan Elm stood near Circleville, Ohio. 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). [60] Weakened by Dutch elm disease, the tree died in 1964 from storm damage. [60]
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Dutch elm disease is a pathogen spread by beetles that devastated American elm, other native elms are more resistant; Thousand cankers disease is a fungus carried by a beetle that infests black walnut; Oak wilt is a fungal pathogen spread by sap beetles that infects oaks; Beech bark disease is a fungus carried by a scale insect that infests ...