Tree of Heaven, Ailanthus altissima  

By Lenny Farlee, Ron Rathfon, Don Carlson, Brian Beheler

Tree-of-heaven (ToH), also known as Chinese sumac, varnish tree, or stink tree, is a large, rapidly-growing deciduous tree native to parts of China. Tree-of-heaven was introduced to the North America as early as the late 1700’s and has since become invasive in most areas of the US (Figure 1). Tree-of-heaven can be a large tree over 80 feet tall and 3 or more feet in diameter, outpacing the growth rate of most native tree species on a wide range of sites. Long, alternately-arranged compound leaves with up to 25 leaflets are borne on stout twigs. Leaflets typically have one or more small glandular teeth located at the base (Figure 2). Species with similar leaves, like black walnut or native sumac species, lack this feature, having smooth leaflet margins, or teeth along the full length of the leaflet. Twigs are stout with very large V or heart-shaped leaf scars and large tan or brown spongy pith in the center. All parts of the plant when crushed or damaged have a foul odor, sometimes described as smelling like rancid peanut butter (Figure 3).

Figure 1. Reported range of tree-of-heaven by county in green. EDDMapS. 2023. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem

Health. Available online at http://www.eddmaps.org/; last accessed June 16, 2026.

Figure 2. Tree-of-heaven leaflet margins and glands.

Figure 3. Tree of heaven twig with leaf scars and buds.

Management

Controlling tree-of-heaven can be challenging. Preventing the introduction of ToH to new areas is dependent on controlling seed production and spread. USDA Forest Service researchers have recommended elimination of seed-producing ToH six years prior to timber harvests to limit the capacity of stored seed in the soil to germinate and produce new populations. Identifying and killing any seed-producing ToH as soon as possible is an important preventative activity. Considering that long-distance seed may disperse, cooperation among property owners may be required to effectively limit seed spread. Monitor forest and wildland areas regularly to detect new infestations, particularly edge and disturbed areas where bare soil or sunlight is available. Act quickly when ToH or other invasive plants are found to eliminate seed production and begin a control program to manage the infestation. This process of early detection and rapid response can prevent large infestations, keep control and management costs from exploding, and limit the ecological impact of the invasive plants in the area.

Existing populations of ToH will require evaluation and development of a management program for control. An assessment of the size and density of the ToH and the site conditions of the area to be managed will help inform the techniques and materials to be used to control the population. Combining several management techniques over a period of time is often necessary to effectively control and manage ToH. Before using herbicides, read the label to check active ingredient (ai) concentration and all safety and application instructions. Adjust rates accordingly for labels with different ai concentrations.

Mechanical treatments alone are typically not effective at controlling ToH. Some small seedlings may be pulled, but root fragments left behind may produce new plants. It can also be difficult to tell seedlings from root sprouts, which are not easily controlled with pulling. Cutting down or girdling stems will produce significant stump and root sprouts, multiplying populations. This may be effective at killing ToH stems and preventing seed production if repeated on a regular basis, but will not control the root systems. The stump and root sprouting response prompted by cutting or girdling can occur even when herbicides are used on the cut stump or in a girdling cut. Fire may also kill the tops of seedlings or saplings, but root systems will not be killed and can produce abundant sprouts. There may be situations where felling ToH is warranted, to limit seed production and spread, or for safety considerations. In these cases, treatments the following growing season to control the sprouts with foliar herbicide applications will be a critical step to success. Waiting more than one or two growing seasons may result in sprouts too tall to efficiently or effectively treat by ground-based foliar methods.

When possible, use the hack-and-squirt technique in place of felling or complete girdling cuts around the circumference of the stem. Hack-and-squirt treatment, combining spaced cuts with herbicide application in the cuts, may reduce the number of root-sprouts produced. Using a narrow cutting tool, like a shingle hatchet or a hatchet ground down to a 2-inch blade, make evenly spaced cuts at a 45-degree angle around the circumference of the tree. The number of cuts should be approximately the diameter of the tree in inches, with uncut spaces between the cuts. Spray one to two milliliters (one to two squirts from a trigger squirt bottle – check your bottle application rate) of herbicide in each cut immediately after making the cuts. Avoid over-application of herbicide that runs down the stem. This material is not impacting the target-tree and may damage non-target plants nearby.

Basal bark application of triclopyr ester herbicides is a very effective control method for TOH. This method does not require any cutting tools (Figure 4). A mixture of an oil and ester herbicide is applied to the lower 15-18 inches of the trunk of the tree to be controlled, covering the bark and root flares. The oil acts as a penetrant, carrying the herbicide into the plant. This treatment greatly reduces the number of sprouts produced by tree-of-heaven. This application is very effective during the last half of the growing season, but care should be taken to avoid applications during hot weather above 85 degrees F, as volatilization of the herbicide/oil mixture can occur, impacting non-target plants and potentially reducing application efficacy. Some sources also recommend this treatment for late winter to early spring as well, but it should not be used when there is snow cover or stems are wet. Discontinue basal bark applications later in spring when sap is moving up in the tree as reduced efficacy has been reported. You may also consider treating the ToH with a basal bark or hack-and-squirt herbicide treatment at least 30 days prior to felling the trees, when that is needed to reduce seed spread or for safety considerations. This allows herbicide to move to and kill the root system prior to cutting the tree, limiting the root sprouting response.

Figure 4. Basal bark application of ester herbicide and oil mixture applied to the lower 15-18 inches of stem.

Foliar application of herbicides to actively-growing leaf area may be a very effective control technique for smaller plants. Large sprout patches or taller stems may be treated if high-pressure sprayers or aerial equipment is available. This is also an effective follow-up treatment to control root sprouts and seedlings. Complete coverage of the live leaf area is needed for effective control.

Summary

For all control strategies, return to the site in following growing seasons to scout for and treat sprouts and germinating seed. Even the best treatments don’t prevent all sprouting, and seed from recently-controlled trees or neighboring infestations may produce new plants. Foliar treatments with 2-3% glyphosate concentrate in water, and other recommended foliar treatments, are effective for this follow-up work on seedlings and sprouts. In addition, keep good records of your control work, including timing, weather conditions, tools, techniques, and materials used to track the effectiveness of your treatments. Good record-keeping and follow-up evaluation of treatments can help tune prescriptions to improve results in future management actions. For more information about controlling Tree of Heaven see https://extension.purdue.edu/extmedia/FNR/FNR-633-W.pdf

Lenny Farlee is a sustaining hardwood Extension specialist with the Hardwood Tree Improvement and Regeneration Center at Purdue University. Ron Rathfon is an Extension forester with Purdue University at the Southern Indiana Purdue Agricultural Center. As a forester, Don Carlson manages properties around the state for the Department of Forestry and Natural Resources at Purdue University.  Brian Beheler is a senior farm operations administer for the Department of Forestry and Natural Resources at Purdue University.