In some areas along the Chadakoin River, Tree-of-heaven is rapidly becoming the only remaining bank tree species. Photo by Twan Leenders

One way of categorizing plants is based on their origin: native plants are those that have lived in an area since before humans altered the landscape. Conversely, non-native plant species are those that arrived more recently – often with our help. Well-known plants in the latter group include many agricultural crops, the ornamental plants that we use to decorate our gardens, as well as many European species that have long ago become an integral part of our landscape (think Dandelions).

A subset of these newcomers has the potential to spread out of control and cause negative impacts on our environment and/or economy. Usually because they left the predators, grazers, or diseases that provide biological control behind. Such species are generally referred to as harmful invasive species. Common examples in our area include Japanese Knotweed, Eurasian Honeysuckle, or Garlic Mustard – all spread rapidly into roadsides and other disturbed areas and outcompete native plants. Even though the spread of any harmful invasive carries an ecological and financial cost, some can literally change our landscape. One of such species, the “Tree-of-heaven,” is establishing a foothold along the Chadakoin River in Jamestown and needs our immediate attention.

Why does one type of plant pose such a great risk to our area? The answer is two-fold: the tree itself is damaging to our environment, but it also attracts a second harmful invasive species: the Spotted Lanternfly. This bug has the potential to deal a devastating blow to our grape, agricultural and forestry industries if it reaches our area.

Tree-of-heaven (Ailanthus altissima), commonly referred to as “ailanthus,” is a very fast-growing tree native to China. Its common name is likely derived from its speedy growth habit, as it can reach “heaven” quickly. Tree-of-heaven thrives in very poor soils, in exposed locations, and under tough growing conditions, which allowed it to become widespread in many urban areas. It exudes chemicals from its leaves, roots, and bark that limit or prevent the establishment of nearby other plants, so it can maintain its dominance once established. Also, these trees are hard to kill. Cutting one down will cause dozens of sucker sprouts to emerge from the stump and its root system. If done incorrectly, attempts to remove these trees can have the opposite effect!

Tree-of-heaven is also the preferred host plant for the Spotted Lanternfly (Lycorma delicatula), originally from China and first detected in the US in 2014. This bug is now firmly established in eastern Pennsylvania and spreading. Lanternflies feed on a variety of fruit, ornamental, and woody trees and are particularly fond of grapes and apples. While feeding, they excrete a sugary substance that covers everything beneath them. Park benches, playground equipment, picnic tables, etc. quickly become covered by this sticky honeydew, which then grows black mold. On a larger scale, a 2020 study by economists in Penn State’s College of Agricultural Sciences projects that, if not contained, the economic impact of Spotted Lanternfly infestations on Pennsylvania’s economy could potentially range from $324-554 million annually and lead to the loss of 2,800-5,500 jobs. Imagine what will happen if this bug reaches Chautauqua County!

There are several significant stands of Tree-of-heaven growing along the banks of the Chadakoin River. A rigid eradication regime will need to start with targeted chemical treatment of each individual tree and requires ongoing monitoring and retreatment over the next 2-3 years, until all trees and their root systems are dead and can be removed.

CWC has taken on a leadership role in restoring and activating the Chadakoin River. The first phase of a multi-year project was recently completed, supported by ARPA funds awarded by Jamestown’s City Council. The next phases focus on invasive species removal, revegetation of riverbanks with native plants, and development of a strategic plan for the river. CWC staff has mapped Tree-of-heaven stands in the project area and developed an invasive species management plan to address the existing threat of Tree-of-heaven and mitigate the potential threat of a Spotted Lanternfly invasion. Pro-actively investing in eradication of these harmful trees may spare us from a potentially devastating environmental and economic disaster down the road.

Since Tree-of-heaven is a veritable Spotted Lanternfly magnet, the USDA Animal and Plant Health Inspection Service (APHIS) started monitoring a stand in 2021 to assess whether the bugs reached Jamestown yet. Trees were injected with a chemical that kills Lanternflies feeding on tree sap and a collecting tray was placed around the trunk. Fortunately, no Spotted Lanternflies have been detected yet, but we have to take action now!

To learn more about Tree-of-heaven, visit https://extension.psu.edu/tree-of-heaven.

The Chautauqua Watershed Conservancy is a not-for-profit organization with the mission to preserve and enhance the water quality, scenic beauty and ecological health of the lakes, streams, wetlands and watersheds of the Chautauqua region. For more information, call 716-664-2166, visit chautauquawatershed.org and follow CWC on Facebook and Instagram.