Ailanthus, also known as tree-of-heaven or Chinese sumac, is a persistent and aggressive weed throughout much of Europe and North America. Ailanthus grows quickly and can reach a height of 2.5 m (8 ft) in its first year; ultimately these trees are 25-30 m (80-100 ft). It flowers in late May through early June and may produce several hundred flowers each year, each of which forms clusters containing hundreds of seeds. Single trees may produce up to 350,000 seeds in one year. Seeds are small, easily dispersed by wind, and mostly viable. Trees also reproduce readily via root sprouts that can emerge up to 15 m (50 ft) from the nearest trunk. It is a ready colonizer of disturbed sites both in urban and natural areas but is intolerant of full shade. Once established, its primary mode of reproduction is through root suckers. The compound leaves of tree-of-heaven resemble those of staghorn sumac, but tree-of-heaven can be distinguished by its foul-smelling leaves.
Management Options:
A. Hand Pulling:
Young seedlings of Ailanthus can be pulled by hand, but they will develop a significant taproot within 3 months and then will become very difficult to remove. Thus, plants should be pulled as soon as they are large enough to grasp. Seedlings are best pulled after a rain when the soil is loose. The entire root must be removed since broken fragments may re-sprout.
B. Cutting:
Larger trees may be cut 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, re-sprouts are common after treatment. Two cuttings per year may be necessary, one early in the growing season and one late in the growing season. Although plants may not be killed after cutting, seed production will be inhibited and vigor will be reduced. If continued for several years, plants will be severely stressed by cutting and will eventually be killed.
C. Girdling:
Use this approach for large trees. Using a hand-axe, make a cut through the bark approximately 15 cm (6 in) above the ground, and cut completely around the trunk. Be sure that the cut goes well into or below the cambium layer. This method will kill the top of the tree but re-sprouts are common, and may require follow-up treatments for several years.
D. Herbicides:
Tree-of-heaven tends to be more susceptible to triclopyr than to glyphosate, especially prior to late summer. Where possible, foliar sprays are effective once the leaves are fully expanded. For larger trees, three approaches are possible: 1) Girdle the tree (see description above) with an axe, and apply undiluted triclopyr in the cut around the trunk; 2) Cut down tree and apply undiluted triclopyr into the freshly cut surfaces of the stump to prevent re-sprouting, or 3) Cut down tree and spray re-sprouts before they get too tall to spray.
BRUSH-B-GON [triclopyr (8%)]:
Foliar spray: 4 fl. oz./gal
Cut-stump treatment: Undiluted
ROUNDUP [glyphosate (41%)]:
Foliar spray: 2.5 fl. oz./gal
Cut-stump treatment: Diluted with equal part water (1:1)
References
Invasive and Alien Plant Species of Virginia. Tree-of-Heaven (Ailanthus altissima (Miller) Swingle). http://www.state.va.us/%7Edcr/dnh/invlist.htm
Tennessee Exotic Plant Management Manual, April 1997.