Once you learn about non-native invasive plants they seem to be everywhere! One of the worst of these—Ailanthus altissima—has the misleading common name “Tree of Heaven.” Introduced as an ornamental, Ailanthus is an attractive, fast-growing tree—but when cut back it can sprout up more than 10 feet a year! Water and wind can spread seeds that will grow new trees as tall as 6 feet their first year.
Ailanthus trees produce a lot of pollen and all parts of the tree can produce skin irritation in some individuals. If that doesn’t give you pause, we now have a new reason to double down on eliminating this invader: it is the preferred host tree for an exceedingly destructive insect, the spotted lanternfly (Lycorma delicatula), which may be making its way south! Removing Ailanthus now will make North Carolina less hospitable to this planthopper, which is a major pest of many fruits, including apples and grapes.
How to know if you have tree of heaven?
Characteristics to look for:
- Bark: Smooth bark that looks somewhat like cantaloupe skin.
- Leaves: Each leaf has from 10 to 40 leaflets with smooth edges, except for 1 to 2 “teeth” at the bottom of each leaflet. Leaves have a very strong peanut-butter odor.
- Flowers: Yellowish flowers April through June.
- Seeds: Winged seed pods in large clusters that may stay on the trees in winter.
Tree of heaven is difficult to control because of its extensive root system and re-sprouting ability. Success depends on treatment timing and following up the next year. Be sure to wear gloves and other protective clothing when removing tree of heaven because of the possibility of allergic reactions.
- Hand-pull young seedlings as soon as they are large enough to grasp. They are best pulled after a rain loosens the soil.
- Remove the entire root because small root fragments are capable of generating new shoots.
- Note that root suckers are easily confused with seedlings and are nearly impossible to pull by hand.
- Although cutting down a tree of heaven will cause it to re-sprout and sucker, you may want to prune out limbs during the winter after leaf fall.
- If seed clusters are present on cut limbs, collect, bag, and dispose of in heavy trash bags so they will not sprout have a chance to sprout.
- Herbicides containing the active ingredient triclopyr are effective. Apply all chemical treatments between July 1 and when the tree begins to show fall colors.
- When removing a tree of heaven, use foliar herbicide sprays where tree height and distribution allow effective coverage without unacceptable contact with nearby desirable plants.
- Treat the foliage with an herbicide first, allow 30 days for it to take effect before cutting the tree down.
Native alternatives for Ailanthus altissima
Suggested by NCSU’s “Going Native” website:
- Hickories (Carya)
- Fringetree (Chionanthus virginicus)
- Green Ash (Fraxinus pennsylvanica)
- Smooth Sumac (Rhus glabra)
Article by Debbie Green, Extension Master GardenerSM Volunteer
For more information:
More on landscaping with native alternatives:
Spotted lanternfly watch: