The tree-of-heaven, scientifically known as Ailanthus altissima, is a deciduous tree whose origin is northeast and central China and Taiwan (Jackson and Gover). The tree of heaven, sometimes going by the name ailanthus, is believed to get its way into the United States in Pennsylvania in 1784. Since then, it has spread increasingly in Pennsylvanian Forests [1]. The spotted lanternfly, scientifically known as Lycorma delicatula, is an invasive pest native to Asia (China and Southeast Asia) that entered the United States in 2014 [2]. Current statistics show that the spotted lanternfly exists in more than twelve Pennsylvania counties and other neighboring areas, among them Virginia, Maryland, New York, Delaware, and New Jersey [2]. The spotted lanternfly is closely related to the tree of heaven in that the latter is attracted to the former for habitat.
Spotted Lanternfly
Four years after making it into the U.S., the spotted lanternfly is increasingly becoming a threat to the survival of various economically valuable crops. This is an invasive pest that can feed on more than 70 species of trees and vines, and shrubs [2]. The pest has been reposted to invade grapes, fruits, hops, hardwoods, and ornamentals, putting the productions of affected crops at significant risk of deteriorating [1].
Evidence of attack by this pest includes dead shoots on some host plants, speaking of which the effect on black walnut trees has been observed in Pennsylvania [2]. The tree-of-heaven is as much aggressively spreading across forests and woodlands in Pennsylvania and is becoming a common sight in urban environments and disturbed sites such as transportation structures and cracks on sidewalks [1-3].
This invasive tree has various impacts: besides its roots producing chemicals that hinder other plants’ growth, its ability to grow fast reduces habitat for other species [4]. The extensive root system of these invasive plants can also damage sewer lines and building foundations. The tree hosts the invasive spotted lanternfly, hence leading to additional impacts.
Tree-of-Heaven
The tree-of-heaven can grow as tall as 80 feet high, while their trunks can grow as thick as 6 feet in diameter [4]. The trees have pinnately compound leaves with 10-41 leaflets whose leaf margins are smooth. The rancid smell can also identify the plants that the leaves and plant parts produce upon crushing, which feels like cat urine or burnt peanut butter [4].
Also, the plants flower in early summer; at this time, “large clusters of yellowish flowers develop above the leaves. The fruit produced on the female trees is tan to reddish, single winged, papery seeds called samaras” [4]. Spotted lanternflies can be identified mainly by their grey and black-spotted forewings, hindwings with contrasting red and black patches with a white band, black legs, and head, and a yellow abdomen with broad black bands [4].
As mentioned above, the tree-of-heaven can thrive almost anywhere. Common sites are woodland edges, urban areas, roadsides, railways, and forest openings [3]. The invasive plant can also thrive in mine spoils with sun and fertile partly shaded alluvial soils bordering rivers/streams, as Jackson and Gover found out. While this invasive plant is weak under a closed forest canopy, it can quickly colonize disturbed areas and take advantage of forests affected by insects or adverse weather conditions.
As already said, the primary habitat for the spotted lanternfly is the tree-of-heaven. Still, at times the insect can thrive on American beech, sycamore, black birch, black cherry, and white ash willows, among others [3]. These insects lay eggs in masses that resemble small patches of mud, such as vehicles, tree trunks, bricks, and boulders, among other outdoor places [4].
The tree-of-heaven has an extensive root system with an ability to resprout [3]. This ability makes the control of these species a challenge. Manual pdf However, various mechanical and chemical methods are being applied to control the spread of the plants. Mechanical methods applied include cutting and mowing, but which are significantly ineffective due to the sprouting ability of the tree-of-heaven [3].
Invasive Removal
Treating the trees with herbicides 30 days before cutting them down can improve the results. Hand pulling of the seedlings can also be used, but it should be done when the soil is moist and ensure the entire root system is removed [3]. Generally, the most effective means of controlling the tree-of-heaven is removing the root system combined with herbicides’ systematic application.
For effective results, control measures should be applied in the mid-to-late summer, when herbicides can travel together with carbohydrates to the roots, hence destroying them, as Jackson and Gover note. The application of herbicides should target foliage, bark, or frill cuts on the stem. Herbicides such as dicamba, glyphosate, imazapyr, metsulfuron-methyl, and triclopyr are among the many that can be used to control the tree-of-heaven [3].
The spotted lanternfly’s effect manifests in trees in the form of weeping wounds, which leave greyish black trails on the trunk [4]. The control of the spotted lanternfly primarily focuses on the destruction of their egg masses, as this reduces the rate of increase of the population and spread of the insects [4]. Considering the common egg-laying spots identified earlier, people are advised to check their vehicles and outdoor equipment for the presence of lanternfly eggs before leaving an area.
Similarly, nursery trees and other things should not be moved out of quarantined areas. Keeping vehicle windows rolled up in lanternfly-infested areas can be a significant control measure. Removal of the tree-of-heaven is another significant control measure considering the lanternfly’s high preference for these trees for a host.
References
1. Finley J. Tree-of-heaven and the Spotted Lanternfly: Two Invasive Species to Watch (Center for Private Forests) [Internet]. Center for Private Forests (Penn State University). 2018 [cited 7 November 2019]. Available from: https://ecosystems.psu.edu/research/centers/private-forests/news/2018/tree-of-heaven-and-the-spotted-lantern-fly-two-invasive-species-to-watch
2. Johnson A, McCullough D, Isaacs R. Spotted lanternfly: A colorful cause for concern [Internet]. Invasive Species. 2019 [cited 7 November 2019]. Available from: https://www.canr.msu.edu/news/spotted-lanternfly-a-colorful-cause-for-concern
3. Jackson D, Gover A. Tree-of-Heaven [Internet]. Penn State Extension. 2018 [cited 7 November 2019]. Available from: https://extension.psu.edu/tree-of-heaven
4. Barringer L. Invasive Plants in Pennsylvania: Tree-of-heaven [Internet]. Docs.dcnr.pa.gov.
[cited 7 November, 2019]
. Available from: http://www.docs.dcnr.pa.gov/cs/groups/public/documents/document/dcnr_20033432.pdf