INVASIVE SPECIES ALERT

by Travis Smith

“Tree-of-Heaven” – Ailanthus altissima

Ailanthus, also known as “tree-of-heaven”

is a non-native, invasive, persistent and very aggressive species throughout much of Europe and North America. Tree-of-heaven grows with amazing speed and vigor - it can reach a height of 8’ in its first year and mature trees can reach upwards of 80’ - 100’. Ailanthus is adapted to a wide variety of soil conditions and tolerates drought and rocky conditions extremely well. It has a limited ability to compete in shaded or forested settings, however thrives in light gaps and full sun conditions. It aggressively takes advantage of forests impacted by slides, windstorms, or other natural disasters. Tree-of-heaven reproduces by both seed and root sprouts.

Leaves are pinnately compound (like walnut, hickory and sumac) and depending on size, may have 11-41 leaflets. The edges of the leaflets are smooth except at the base where they have 1-5 teeth. Each leaflet will have at least one glandular tooth along the base. The overall size of the leaf can be in excess of 24” long.

Twigs are light brown, very stout, covered with fine hairs and have a foul, acrid odor when broken.

Flowers form in “heads” above the leaves in May through early June and are light green. Each tree may produce several hundred of the flower “heads”. After the seeds form in early fall, these “heads” turn a showy pink and contain hundreds of seeds.

Eradication and Control

By far the most environmentally sound method for removal of tree-of-heaven stems is the “Cut Stump” method. This greatly eliminates the probability of chemically damaging surrounding vegetation and requires the use of significantly smaller volumes of herbicide.

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 surface 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 surface, making sure to cover the outer 20% of the stump. I have found this to be the more effective herbicide treatment.

For more info contact Travis Smith at smithta@bellsouth.net.

*Photos borrowed appreciatively from

SE-EPPC Invasive Plant Manual*