Fraxinus americana, the white ash or American ash, is a species of ash tree native to eastern and central North America. It is found in mesophytic hardwood forests from Nova Scotia west to Minnesota, south to northern Florida, and southwest to eastern Texas. Isolated populations have also been found in western Texas, Wyoming and Colorado, and the species is reportedly naturalized in Hawaii.
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Characteristics
The name white ash derives from the glaucous undersides of the leaves. It is similar in appearance to the green ash, making identification difficult. The lower sides of the leaves of white ash are lighter in color than their upper sides, and the outer surface of the twigs of white ash may be flaky or peeling. Green ash leaves are similar in color on upper and lower sides, and twigs are smoother. Despite some overlap, the two species tend to grow in different locations as well; White ash is a forest tree that commonly occurs alongside sugar maple while green ash is a pioneer species that inhabits riparian zones and disturbed areas.
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Cultivation and uses
White ash is one of the most used trees for everyday purposes and, to keep up with high demand, is cultivated almost everywhere it can be. The wood is white and quite dense (within 20% of 670 kg/m3), strong, and straight-grained. It is the timber of choice for production of baseball bats and tool handles. The wood is also favorable for furniture and flooring. Woodworkers use the timber mainly for interior uses due to high perishability in contact with ground soil. It is also used to make lobster traps. Since the 1950s, it has also become a popular choice for solid electric guitar bodies. It makes a very servicable longbow if properly worked. The wood was used in ceiling fan blades from the 1970s through the mid-1980s, though cane was sometimes simulated with plastic then. It is no longer used for ceiling fan blades in most countries.
White ash is not seen in cultivation as often as green ash due to its preference for undisturbed forest sites away from urban pollution and soil compaction, but sometimes has been planted for its consistently reliably autumn colors, which typically are bright orange and red hues as opposed to other species of ash that produce a uniform yellow color.
A related species, Biltmore ash, is sometimes treated as a variety of white ash. However, other taxonomists argue that Biltmore ash is its own species (Fraxinus biltmoreana).
Emerald ash borer
The emerald ash borer (Agrilus planipennis), also commonly known by the acronym EAB, is a green beetle native to Asia.
In North America the emerald ash borer is an invasive species, highly destructive to ash trees in its introduced range. The damage of this insect rivals that of Chestnut blight and Dutch Elm Disease. To put its damage in perspective, the number of chestnuts killed by the Chestnut blight was around 3.5 billion chestnut trees while there are 3.5 billion ash trees in Ohio alone. Dutch Elm Disease killed only 200 million elm trees while EAB threatens 7.5 billion ash trees in the United States. The insect threatens the entire North American genus Fraxinus, while past invasive tree pests have only threatened a single species within a genus. Since its accidental introduction into the United States and Canada in the 1990s, and its subsequent detection in 2002, it has spread to eleven states and adjacent parts of Canada. It has killed at least 50 million ash trees so far and threatens to kill most of the ash trees throughout North America. The green ash and the black ash trees are affected. White ash is also killed rapidly, but usually only after green and black ash trees are eliminated. Blue ash displays some resistance to the emerald ash borer by forming callous tissue around EAB galleries; however, they are usually killed. White ash has been less affected by emerald ash borer due to its small population (unlike its cousin, F. americana is not commonly seen in cultivation) compared to green ash, which was planted in huge numbers as an ornamental.
Source of the article : Wikipedia
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