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Moment of Nature - July 26, 2013
Least wanted: an intruder among us
Ailanthus seeds Web
An example of the Ailanthus seeds and leaves, which are toothed instead of smooth like the leaves of other, similar trees. Crushing the leaves produces a rotten aroma.


I do not consider myself an alarmist nor do I normally get overly excited about things, but there is definitely cause for concern regarding a recent find in town. In late May, I performed a residential tree check in the Kendall Lake area. As a general rule, I do my best not only to look at the tree of concern but also to walk the property to make sure other trees are OK as well. In doing so at this particular property, one tree caught my eye. Then I saw another and another and another. My first thought was, “Uh-oh;” my second thought was, “If they are at this property, where else are they?”

In the following month and a half with my eye sharpened on the fact that this tree is here in town, my focus was honed in on scouting for this most unwelcomed guest. Since that initial finding, pockets of this intrusive, obnoxious and nuisance tree have been found along Kirkwood Lane, Polo Lane, lower Fair Street, Mill Street, Wylie Street, Chestnut Ferry Road and upper Lyttleton Street, so far. This is one leafy neighbor we do not want settling roots here. In fact, its control and removal are now Priority One on my to-do list before summer’s end.

This least wanted tree is commonly called tree-of-heaven or ailanthus (Ailanthus altissima). While the name may sound lovely and conjure visions of an angelic tree, this is one of the most invasive, pervasive, domineering and pesky nuisance trees here in the southeast -- worse than kudzu in my opinion. It can literally overrun an area in a matter of just a few years and choke out native plant species. In fact just last week, while pruning crape myrtles in an 8-foot by 12-foot planting island where I had pruned last year, I found 20 -- yes that’s 20 -- knee-high tall seedlings. I am now alarmed people, very alarmed.

According to Phil Pannill, U.S. Fish and Wildlife Service, Shepherdstown, West Va., and Jil Swearingen, National Park Service, Center for Urban Ecology, Washington, D.C., in a fact sheet they wrote for the Plant Conservation Alliance’s Alien Plant Working Group in 2009, ailanthus, also known as Chinese sumac and stinking sumac, is a deciduous tree that can reach 80 feet in height. Ailanthus has smooth stems with pale gray bark and twigs which are light chestnut brown. Its very large compound leaves are 1 to 4 feet in length, alternately branched and composed of 10 to 41 smaller leaflets. The fruit are flat, twisted, winged seeds that occur in clusters at the end of branches during late summer and may persist on the tree through the fall.

It is important not to confuse ailanthus with native trees such as ash, hickory, black walnut and pecan, which can be distinguished from ailanthus in two ways. First, the leaf edges of ailanthus are somewhat toothed instead of smooth like the trees mentioned above; and, second, is to crush or break the leaves or twigs and smell the distinct rotten peanut butter aroma it exudes. If it smells, it’s got to go.

Ailanthus would be a great tree if it weren’t for its extremely fast-growth rate, which tends to produce brittle wood but more importantly its prolific seeding, which can result in the take-over a local ecosystem. One study reports that an individual tree can produce as many as 325,000 seeds per year, making it one of the most dangerously invasive trees. Nationally, ailanthus is recognized to be a serious agricultural pest and is listed on practically every non-native invasive tree list throughout the United States.

The primary concern regarding this tree is its ability to sprout up just about anywhere, including vacant lots, ditch banks, woodlands, sidewalks, parking lots and streets. It occurs as seedlings that germinate by the hundreds if conditions are right. Established trees also produce numerous suckers from the roots and re-sprout vigorously from cut stumps. I see ailanthus as the modern-day beanstalk of the famous Jack in the Beanstalk fairy tale. Release a seed on the ground, give it a drop of water and away it grows!

Ailanthus is a tree native of China and was first introduced to America by a gardener in Philadelphia, Pa., in 1784, and by 1840 was commonly available from nurseries. The species was also brought into California by Chinese immigrants who traveled oversees during the Gold Rush in the mid-1800s. Today, it is frequently found in abandoned California mining sites as well as in 42 other states and two Canadian provinces.

As mentioned earlier, the control, removal and eradication of this tree is now my priority, no, my mission. Elimination of ailanthus requires diligence, due to its abundant seed production, high seed germination rate and vegetative reproduction.

Three approaches to control and eradication of this invasive tree are available. Manual: young seedlings may be pulled or dug up, preferably when soil is moist. Care must be taken to remove the entire plant including all roots and fragments, as these will almost certainly regrow. Mechanical: cutting down tall saplings and large trees is usually counter-productive because ailanthus responds by producing large numbers of stump sprouts and root suckers, potentially making even more seeds. Repeated cutting of sprouts over time can exhaust the plants reserves but this is <italic>not</italic> a good option for immediate eradication. Chemical: the most successful method of ailanthus control is through the use of herbicides, which may be applied to the leaves, a cut stump or to the trunk via vascular injection. The trunk application method is probably the most effective as it is specifically labeled for and directed to treat the root system of the targeted tree and kill it.

In the coming weeks, I’ll complete my research of the situation, compile a tally of the tree’s locations around the city and procure a professional to begin control methods. Unfortunately, not all of the trees are within the public street rights-of-way and we may need your help to effectively manage this unwelcome intruder. In the meantime, if you see this tree or think you may have this tree on your property, please contact me at the Camden Department of Public Works at 425-6045.