The Wildlife Habitat Council’s Chicago office is currently restoring a dune and swale woodland at ArcelorMittal Burns Harbor, a steel mill located in Northwest Indiana.
One of the most problematic invasive species on site is Ailanthus altissima, the Tree-of-Heaven. Sometimes affectionately referred to as “Tree of Hell” or the “Ghetto Palm” because of its tendency to grow anywhere, even in the cracks of sidewalks, the Tree-of-Heaven was introduced to Philadelphia in 1784 as an ornamental. It quickly declined in popularity because it spreads laterally through roots and once cut, it resprouts prolifically and is very difficult to remove. The foliage also produces an unpleasant odor in the spring which causes nausea. The plant escaped cultivation and can now be found in most of the US. New saplings grow at an incredible pace, up to six feet per year! The rapid growth creates dense stands that outcompete native woody species. Studies published in the Journal of Arboriculture and Urban Forestry and Proceedings of the 17th Central Hardwood Forest Conference suggested that use of Tricoplyr, an oil-based herbicide, will kill over 90% of treated trees with one application.
We decided to use two methods cited by the studies to see which worked best at our ArcelorMittal ecological restoration site. First, we used the “Hack and Squirt” method (for trees >18” in diameter), where an axe is used to create notches in the bark, then Tricoplyr is squirted in. Second, we tried the “Basal Bark Spray” method, where the bottom 18” of the tree trunk is sprayed with Tricoplyr. Yesterday we checked on our results a week after treatment and were happy to see good progress with both methods. Smaller trees are dead and larger trees have yellowing leaves. We will be monitoring the site over the next few weeks and adjusting our techniques accordingly. Check out some of our pictures, and contact Colter Sonneville at the Chicago Field Office (219-286-7049) if you have and questions about removing Tree-of-Heaven from your natural areas.
Bowker, D & Stringer, J (2007) . Efficacy of herbicide Treatments for Controlling Residual Sprouting of Tree-of-Heaven . Proceedings of the 17th Central Hardwood Conference, 128-133.
DiTomoso, J.M. & Kyser, G.B. (2007) . Control of Ailanthus altissima Using Stem Herbicide Application Techniques. Arboriculture & Urban Forestry, 33(1): 55-63