Southeast Exotic Pest Plant Council Invasive Plant Manual
Common Name: Tree-of-Heaven
Scientific Name: Ailanthus altissima (Mill.) Swingle
Ailanthus, also known as tree-of-heaven or Chinese sumac, is a persistent and aggressive weed throughout much of Europe and North America. It belongs to the Simaroubaceae (Quassia) family, which is primarily tropical or subtropical. Ailanthus grows quickly and can reach a height of 2.5 m (8 ft) in its first year.
Ailanthus may be confused with other trees having compound leaves and many leaflets; particularly black walnut (Juglans nigra L.), butternut (Juglans cinerea L.), and some species of sumac (Rhus spp.). The leaf margins of these trees have small teeth (except for winged sumac), while those of ailanthus are smooth. The gland-tipped leaflet lobes are unique to ailanthus, as is the foul odor produced by crushed foliage and scraped bark. In winter ailanthus may be distinguished by the stout twigs, large leaf scars with numerous bundle scars, and false end buds.
Ailanthus is adapted to a wide variety of soil conditions. It tolerates drought and rocky conditions to the extent of growing out of pavement cracks. The tree is common in urban areas and disturbed sites throughout its range, and it is a pioneer in succession with limited ability to compete in a closed-canopy forest. It can, however, take advantage of forests defoliated by insects (e.g., gypsy moth) or impacted by slides, windstorms, or other natural disasters. Ailanthus forms dense, clonal thickets that displace native species. A few trees along a fencerow or forest edge can rapidly invade adjacent meadows. In addition to its prolific vegetative reproduction, ailanthus has allelopathic effects on many other tree species and may consequently inhibit succession.
Cutting: Cut trees at ground level with power or manual saws. Cutting is most effective when trees have begun to flower to prevent seed production. Because ailanthus spreads by suckering, resprouts are common after treatment. Cutting is an initial control measure, and success will require either an herbicidal control or repeated cutting for resprouts.
Girdling: Use this method on large trees where the use of herbicides is not practical. Using a hand axe, make a cut through the bark encircling the base of the tree, approximately 15 cm (6 in) above the ground. Be sure that the cut goes well into the cambium layer. This method will kill the top of the tree but resprouts are common, and may require follow-up treatments for several years until roots are exhausted.
Hand Pulling: Ailanthus is effectively controlled by manual removal of young seedlings. Plants should be pulled as soon as they are large enough to grasp, but before they produce seeds. Seedlings are best pulled after a rain when the soil is loose. The entire root must be removed since broken fragments may resprout.
Herbicidal Controls Foliar Spray Method: This method should be considered for large thickets of ailanthus seedlings where risk to non-target species is minimal. Air temperature should be above 65 Â°F to ensure absorption of herbicides.
Glyphosate: Apply a 2% solution of glyphosate and water plus a 0.5% non-ionic surfactant to thoroughly wet all leaves. Use a low pressure and coarse spray pattern to reduce spray drift damage to non-target species. Glyphosate is a non-selective systemic herbicide that may kill non-target partially-sprayed plants.
Triclopyr: Apply a 2% solution of triclopyr and water plus a 0.5% non-ionic thoroughly wetting all leaves. Use a low pressure and coarse spray pattern to reduce spray drift damage to non-target species. Triclopyr is a selective herbicide for broadleaf species. In areas where desirable grasses are growing under or around ailanthus, triclopyr can be used without non-target damage.
Cut Stump Method: This control method should be considered when treating large individual trees or where the presence of desirable species preclude foliar application. Stump treatments can be used as long as the ground is not frozen.
Glyphosate: Horizontally cut stems at or near ground level. Immediately apply a 50% solution of glyphosate and water to the cut stump making sure to cover the outer 20% of the stump.
Triclopyr: Horizontally cut stems at or near ground level. Immediately apply a 50% solution of triclopyr and water to the cut stump making sure to cover the outer 20% of the stump.
Basal Bark Method: This method is effective throughout the year as long as the ground is not frozen. Apply a mixture of 25% triclopyr and 75% horticultural oil to the basal parts of the tree to a height of 30-38 cm (12-15 in) from the ground. Thorough wetting is necessary for good control; spray until run-off is noticeable at the ground line.
Hack and Squirt Method: Using a hand axe, make cuts at 6.5 cm (3 in) intervals around the trunk of the tree between 15-45 cm (6-18 in) above the ground. Be sure that each cut goes well into or below the cambium layer. Immediately treat the cut with a 50% glyphosate or tricloypr herbicide solution.
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