The purple ash tree (Fraxinus americana ‘Autumn
Purple’) is actually a white
ash tree that has purple leaves in fall. Its attractive autumn foliage
makes it a popular street and shade tree. Unfortunately, experts no longer
recommend planting new ash trees since they are susceptible to the deadly pest,
ash borer. Read on for more purple ash tree facts.
Purple Ash Tree Facts
White ash trees (Fraxinus americana) are native to
eastern North America. They are the tallest of native ash trees, growing up to
80 feet (24 m.) in the wild. While the trees have a pyramid form when young,
mature trees have rounded canopies.
The white ash cultivar, ‘Autumn Purple,’ stays somewhat
shorter than the species tree. It is admired for its beautiful deep mahogany
foliage in autumn. These autumn purple ash trees provide long lasting fall
White ash trees are dioecious,
with trees usually being either male or female.
The ‘Autumn Purple’ cultivar, however, is a cloned male, so these trees will
not produce fruit although you will find that these male trees do bear flowers.
Their blossoms are green but discreet. Their other ornamental feature is gray
bark. On mature purple ash trees, the bark sports diamond shaped ridging.
Growing an Ash Tree with Purple Leaves
If you are thinking of growing an ash tree with purple
leaves, you’ll want to first read up on the insect pests that attack this tree.
The emerald ash borer, native to Asia, is the most dangerous. It is considered
a serious threat to all ash trees in this country.
The emerald ash borer turned up in the United States in 2002
and spread fast. These bugs feed under the bark and kill an ash tree within
five years. This borer bug is expected to continue spreading and it is
extremely difficult to eradicate. This is the reason planting new ash trees is
no longer recommended.
Autumn Purple, the ash tree that turns purple, is also
vulnerable to other insect pests. These can include the ash borer, lilac
borer, carpenter worm, oyster shell scale, leaf
webworms, ash sawflies, and ash leaf curl aphid.