Stone: A not so heavenly tree

You are reading the gardening column, you know me, and you have at least heard of, but maybe not experienced the spotted lanternfly firsthand.

I hope that it is evident that I want readers to be educated, empowered, and ready for the call to action. So, let’s go!

I try to align the weekly columns to seasonal topics or a response to calls, emails, conversations, or text messages that I have been receiving. This week it is not SLF specifically, although I have been receiving lots of reports, seeing many active infestations, and talking with residents that are experiencing this pest, but rather I am writing about their preferential host, the tree of heaven. And while they feed on many other plants, it is definitely a favorite and one of two plants that both the nymphs and adults will partake on from the beginning to the end of their feeding frenzy. The second favorite is grapes — both cultivated and wild.

Tree of heaven (Ailanthus altissima) is a non-native species introduced with the best of intentions in the late 1700s. It did not just strive and accomplish its purpose of a horticultural specimen and shade tree with ease of establishment and rapid growth, but rather thrived to the detriment of other plant species and was coined — invasive.

Ever heard of the book, A Tree Grows in Brooklyn ? This is it!

Tree of heaven is dioicous – having separate male and female plants. And while both can be problematic, the female trees add a more troublesome dimension when they reach maturity and can produce hundreds of thousands of seeds or its progeny — little tree of heavens that ultimately grow into bigger tree of heavens.

Tree of heaven is a rapidly growing, deciduous tree that grows up to eighty feet in height and up to six feet in diameter. It has large, heart-shaped leaf scars on its twigs. The bark is smooth with lenticels, is light grey to tan in color, and develops fissures as it grows older. Someone once described the bark as cantaloupe-like, which I think is a great description.

At first glance, the tree’s compound leaves look somewhat like black walnut or sumac, but they typically have more leaflets than the others. The tree of heaven’s leaf, comprised of many leaflets, can be up to three feet long, while black walnut leaves may reach a maximum of two feet, and sumac usually less than that. Tree of heaven leaflets have what is called “glandular teeth” at the base of an otherwise nearly smooth or entire leaf margin. And at the tip of each tooth is a tiny bump, almost pimple-like. If you cannot see it, you can always feel it. Both black walnut and sumac have toothed margins along the outside edge of the leaflets. The tree of heaven has a single terminal leaflet, while most black walnut leaves have two leaflets at the tip. If in doubt, give the leaves a smell test. Hint to the sniffer — the tree of heaven is also called the stink tree and has very distinct odor.

Right now, the female trees, loaded with seeds, stand out and are very obvious. You may even think, wow those trees look amazing, but then remember that those colorful seeds that change from green, to pink to burgundy to brown, can be responsible for the next generation of the invasive trees.

Now that you are loaded with plant identification information, and you discover that you have tree of heaven, what is the next step? You may want to quickly grab your pruners or saw but wait! This tree spreads by rhizomes and has tremendous sprouting capabilities and will actually go into overdrive when the simple action of pruning occurs. So instead of one tree of heaven, there will soon be even more pop up to the disappointment of the person who thought they were doing the right thing by trying to eliminate the unwanted tree.

Herbicide treatments are typically recommended as part of the management strategy when removing tree of heaven. The good news is that now and into the fall is a highly effective time to plot your removal plans. The Ohio State University FactSheet I recommend you reading to learn more can be found at: https://ohioline.osu.edu/factsheet/f-65 .

Before using any pesticide, be sure to read and follow all label instructions. The label is the law.

If you have any questions about tree of heaven, or SLF, contact your local Extension office, or your state’s Department of Agriculture. In Lucas County, Master Gardener Volunteers are available on the Horticulture Hotline on Mondays and Wednesdays from 10 a.m. – 1 p.m.

Amy Stone is an extension educator with the Ohio State Extension – Lucas County, Agriculture and Natural Resources. Contact her at: stone.91@osu.edu.