The common name Tree of Heaven is something of an oxymoron since its impact on fruit cultivation and forest ecosystems is less than heavenly.
This tree species — Ailanthus altissima — is considered one of the most egregious, noxious, and vigorous invasive species in Kentucky, and other places it is found in North America.
Tree of Heaven (Photo provided)
On the UK College of Agriculture Department of Forestry and Natural Resources website page, the Tree of Heaven is one of 11 plant species that are considered woodland health threats.
The invasive plant’s introduction in part said: “Invasive plants are those that have a tendency to take over an area if left unchecked…the ones that cause the most trouble in our woodlands are invasive exotic plants. If not addressed quickly they can spread and become a serious problem for woodlands.”
Tree of Heaven Life History
The Tree of Heaven is a deciduous tree in the family Simaroubaceae. Native to the northeast and central China, it is found in temperate climates.
The Tree of Heaven grows rapidly and is capable of reaching heights of 49 feet in 25 years. Its suckering ability allows it to clone itself indefinitely.
In North America, the invasiveness of the species has been compounded by its harboring of a destructive insect, the Spotted Lanternfly (Lycorma delicatula), a native of China that is a threat to fruit crops, fruit trees and native hardwood tree species.
The Spotted Lanternfly is invasive and can be spread long distances by people who move infested material or items containing egg masses. If allowed to spread in the U.S. this pest could seriously impact the country’s grape, orchard, and logging industries.
Spotted Lanternfly (Photo from Bing Images)
The tree’s bark is smooth and light grey, often becoming somewhat rougher with light tan fissures as the tree ages. The leaves are large, compound on the stem, and range in size and coloration.
Male trees produce three to four times as many flowers as the females, making the male flowers more conspicuous, emitting a foul-smelling odor while flowering attracting pollinating insects.
Outside Europe and the United States, the plant has been spread to many other areas beyond its native range and is considered internationally as a noxious weed.
In many countries, it is an invasive species due to its ability both to colonize disturbed areas quickly and to suppress plant competition with chemicals. The tree also resprouts vigorously when cut, making its eradication difficult, expensive and time-consuming. This has led to the tree being called “the tree of hell,” among many arborists, ecologists and conservationists.
Other Chinese Invasive Plant Species
Two other invasive plant species native to China and other countries in Asia that have been established in Kentucky and parts of North America include:
Amur Honeysuckle (Photo from Flickr Commons)
• With its bright-colored berries and fragrant flowers, the Amur Honeysuckle (Lonicera maackii) may seem like a good candidate for landscaping.
But in the plant world, appearances can be deceiving.
Imported into the U.S., bush honeysuckle was introduced with good intentions. It was planted throughout Indiana from the 1950s to 1970s in home and urban landscaping but escaped and is now a major invasive species, present in more than 30 states in the eastern U.S.
The Amur Honeysuckle (Lonicera maackii) is a bush species native to China, Mongolia, Korea and Russia, named for the Amur River, the world’s eighth-longest river, which forms the border between Russia and Manchuria.
The deciduous, large shrub can grow up to 15 feet tall, and flowers from mid-spring to early summer.
Its fruit is a bright red to black semi-translucent berry containing numerous small seeds. These high carbohydrate “treats,” that ripen in autumn, are eaten by birds, which disperse the seeds in their droppings. That’s why bush honeysuckle often grows in fence lines and roadways, especially along interstate highway corridors, where there is good habitat for songbirds.
Bush honeysuckle can form extremely dense thickets in forest understories, shading out, and out-competing native shrubs, young trees, and wildflowers. This species poses a serious threat not only to the diversity of ecosystems that are invaded but to forest regeneration itself.
Eradication is costly and labor-intensive.
Bush honeysuckle is best controlled by mechanically ripping the shrubs out of the ground, cutting, or burning the plant to root level. To ensure eradication, stumps that are cut should be treated with herbicides.
• Drive down any Kentucky highway during the summer months and bare, gray tree limbs are highly visible among the forest greenery.
These are dead ash trees, killed by the Emerald Ash Borer (EAB). This green, exotic beetle (Agrilus planipennis), feeds on green ash, black ash, white ash, and blue ash trees. Blue ash is an heirloom species in Kentucky. Some individual trees in the Inner Bluegrass Region have been alive since the 18th century.
Emerald Ash Borer (Photo from Bing Images)
The natural range of the emerald ash borer is eastern Russia, northern China, Japan and Korea.
Emerald ash borer probably arrived in the U.S. on solid wood packing material carried in cargo ships or airplanes originating from Asia.
Since its discovery, EAB has killed hundreds of millions of ash trees in North America, and some botanists believe EAB could eventually kill 8.7 billion ash trees on the continent.
EAB has caused regulatory agencies to enforce quarantines and fines to prevent potentially infested ash trees, logs or hardwood firewood from moving out of areas where EAB occurs, and cost municipalities, property owners, nursery operators, and forest products industries hundreds of millions of dollars.
Discovered in southeastern Michigan near Detroit in the summer of 2002, adult beetles nibble on ash foliage but cause little damage. The larvae — the immature stage — feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients.
The Emerald Ash Borer is now confirmed in 29 states and two Canadian provinces, from Minnesota, east to New Hampshire, south to Georgia and west to Colorado.
Its presence was confirmed in Kentucky in the spring of 2009.
Invasive plant species from China and Asia are a threat to native species in Kentucky. Don’t overlook how real this threat is, take action.
