Pesky Tree of Heaven' popular with spotted lantern fly
Invasive tree is everywhere in county and could attract invasive insect
By Rodney L. Sherman
CLARION NEWS Editor
The trees are practically everywhere as they can grow in mine spoil in full sun to fertile, partly shaded, alluvial soils along rivers and streams.
"They" are the "Tree of Heaven," a breed of tree now considered an invasive pest of a tree and recently designated as a favorite home of an even more invasion menace the Spotted Lantern Fly (SLF).
Because the Tree of Heaven is a prolific seed producer and grows rapidly, it successfully competes with native vegetation.
Also, its tissues contain a compound called ailanthone that is toxic to many other plant species.
Its root system is aggressive enough to cause damage to sewers and building foundations.
There's most likely a Tree of Heaven near your home or driveway.
"Tree of Heaven has become a big deal over the last couple years," explained Karlie Sherman,a Tech II and crew leader with FORECON Inc., private forestry consulting company.
FORECON does a variety of timber marking, timber cruising, herbicide application, and tree planting for large land investment companies, federal and state agencies, and private landowners.
"Even though I don't deal with it often, Tree of Heaven still plays a huge role in the forest health," said Sherman. "Not only is it difficult to control, but has become even more of a concern with the discovery of the Spotted Lantern Fly in southwestern Pennsylvania.
"Spotted Lantern Fly is the newest threat to our forests and cause serious damage to trees."
Sherman said it's been found SLF are a lot more successful in reproduction in Tree of Heaven than other trees.
"If Tree of Heaven isn't controlled its possible Spotted Lantern Fly will spread much easier," said Sherman. "Counties with Spotted Lantern Fly had already been put under quarantine."
(Disclosure: Karlie Sherman is a niece of the author of this report. She is a graduate of Clarion University and was working with FORECON before she graduated.)
Besides urban areas, Tree of Heaven is now found growing along woodland edges, roadsides, railways, fencerows, and in forest openings.
Tree of Heaven is intolerant of shade and cannot compete under a closed forest canopy but will quickly colonize disturbed areas, taking advantage of forests defoliated by insects or impacted by wind and other disturbances.
Sherman said she recently completed a Penn State Extension silviculture class focusing on Tree of Heaven.
Silviculture is the practice of controlling the growth, composition, health, and quality of forests to meet diverse needs and values.
"(Tree of Heaven) was brought over from the Asia and planted here in the United States and can out-compete our native plants," said Sherman. "I don't see it on a daily basis in the forest setting. It was commonly planted as ornamental trees in urban areas, but has spread. It's a deciduous hardwood tree and it grows very rapidly."
Even though Tree of Heaven grows quickly the Penn State Extension website says the largest Tree of Heaven in the state is 80-feet tall and 4-feet, 9-inches inches in diameter Sherman said the tree doesn't have much timber value.
State panel declares it a noxious weed'
In April of this year, the state's Controlled Plant and Noxious Weed Committee, a 14-member panel of legislators, horticulturists and representatives of state agencies and nursery owners, approved adding the Tree of heaven to the state's noxious weed list.
The panel based its decision in the tree's invasiveness and its connection to SLF.
By putting the tree on the list, the state can block the sale of the tree seedlings (almost entirely by online sellers), according to the Pennsylvania department of Agriculture.
The state has the power to order property owners to remove plants on the noxious weed list but Pennsylvania has never used that power, and doesn't intend to use it to force landowners to remove the trees, the Department of Agriculture said as it would be too costly for landowners to remove clusters of trees.
Reproduction is rapid
According to Bruce Wenning of the Ecological Landscape Alliance, "the Tree of Heaven is for the most part dioecious, meaning male and female flowers are located on separate plants.
"The light green colored flowers appear from April to May arranged in a multi-branched inflorescence.
"The pollen-producing male flowers have a foul, smelly odor that helps attract some effective pollinating insects such as certain flies, honey bees, many solitary bees, and some beetles.
"More male flowers are produced than female (pollen receiving) flowers. Pollinating insects visit both types of flowers ensuring adequate pollination leading to the development of viable fruit and seed; seed production is high.
"The fruit (samara or schizocarp) appears from August into October, and some fruit can remain attached to the tree into the winter months.
"Both male and female plants must be in close enough proximity to be fertilized by pollinating insects.
"Non-seed bearing trees, which are more common in urban areas than in woodlands, may either be a lone male or lone unfertilized female tree.
"Horticulturists had a preference for female trees because they lacked the foul flower odor. This specific selection or landscape design choice probably has contributed to curtailing Tree of Heaven's spread in some areas."
Human health concerns
According to the Penn State Extension office, Tree of Heaven can affect human health.
The tree is a very high pollen producer and a moderate source of allergy in some people.
In addition, a few cases of skin irritation or dermatitis have been reported from contact with plant parts (leaves, branches, seeds, and bark) and products.
Symptoms often vary and depend on several factors, including the sensitivity of the individual, the extent of contact, and the condition of the plant or plant product.
There are rare reports of myocarditis (inflammation of the heart muscle) from exposure to sap through broken skin, blisters, or cuts.
People who have extensive contact with the tree should wear protective clothing and gloves and be careful to avoid contact with the sap.
Battling the Tree of Heaven isn't easy
So what can you do to battle the invasive tree on which the Spotted Lantern Fly cold thrive if it make it to this part of the state?
Eradicating the tree is hard cutting the tree down doesn't kill it.
Its roots simply sprout new trees. A cut or injured tree may send up dozens of root sprouts. Sprouts as young as two years are capable of producing seed.
Destroying female trees (and thus stopping seed production) is one of the best ways to limit its spread, according to the Pennsylvania Department of Agriculture.
Injuring the root system is critical to killing the tree completely.
Certain herbicides can provide control if applied correctly.
Commercial pesticide applicators can choose among several herbicide products on the market to control Tree of Heaven.
If you choose to treat the trees yourself, a foliar application of an herbicide product that contains 18-41 percent glyphosate can effectively kill Tree of Heaven.
Extensive advice and suggestions for controlling Tree of Heaven can be found on the Penn State Extension's website at https://extension.psu.edu/tree-of-heaven