February 08, 2024
Recently, Joe Rossetti, hardwood initiative coordinator for the Virginia Department of Forestry (VDOF), came to my land to give advice on managing the 38 acres my wife Elaine and I live on. Of course, we did some of the usual timber stand improvement projects, such as daylighting oaks, but the key takeaway point from the visit involved the topic of invasive woody flora such as autumn olive, multiflora rose and ailanthus.
The forester said there’s no bad time to attack invasive trees and shrubs, but the best times are fall and winter when sap isn’t rising like it is in the spring. In those two latter seasons, chemical applications can go straight down into the tree’s or shrub’s root system and be much more effective at killing it.
With that crucial point made, just what are the East’s worst invasive woody plants, and how can we hunters and habitat managers control them?
The Worst Offenders
A rogues’ gallery of the East’s most insidious invasive flora would include the proverbial usual suspects. Rossetti rates, in alphabetical order, these individuals among the most destructive: ailanthus, autumn olive, Callery pear, Chinese privet, Japanese barberry, multiflora rose and Oriental bittersweet. Let’s take a closer look at each of these foul flora.
Ailanthus, also known as paradise tree, stinkwood and tree of heaven, is an Asian native. Ailanthus altissima has the horrible ability to secrete a chemical into the soil that is toxic to other plants, including natives, which often succumb to this witch’s brew. Matters deteriorate even further when copious numbers of seeds are released in the fall, and soon a monoculture exits where nothing grows but the ironically named paradise tree.
Large, compound pinnate leaves, pale gray bark, light brown twigs, pink samara seeds and a foul, fuggy odor characterize an ailanthus. The yellowish-green flowers, which appear in the spring, can alert us to future problems.
Autumn olive (Elaeagnus umbellata) is indigenous to Asia as well and was imported here to prevent erosion and provide food and cover for wildlife. The introduction, of course, became a classic debacle, as stands of this shrub quickly crowd out native plants. The leaves are lance-shaped and silvery beneath. Those shimmery undersides are a great way to identify this plague, as are the speckled stems, often adorned with thorns. When the white blooms appear in spring, they produce a sweet aroma. Later, come summer, round, red-orange berries present themselves. In autumn, birds spread the seeds from the fruits far and wide.
Callery pear (Pyrus calleryana) is often marketed as the cultivar Bradford pear. At first glance, the Asia native might not seem so bad, as it is a fruit producer. However, this rapidly spreading flora often forms dense, thorny thickets where native, beneficial trees and plants can’t dwell. The large thorns and showy white blooms help to distinguish this invasive.
Next on our hit list is Chinese privet (Ligustrum sinense), which obviously hails from Asia. Privet grows up to 30 or so feet tall, but I’ve mostly observed it as a shrub. Among the identifiers are the grayish bark with white blotches; small, bright green, oval-like leaves; foul-smelling flowers; and sucker growth that explains why native plants are typically outcompeted.
Japanese barberry (Berberis thunbergii) often tops out at 3 or 4 feet. The oval leaves display a cluster-like appearance. Come fall, the leaves turn a very attractive red, the same hue as the tiny berries, which are egg-shaped. Foolishly, Japanese barberry was brought here to serve as living fences, but its main claim to shame is its monocultural-type tendencies.
The infamous multiflora rose is yet another Asian escapee. Rosa multiflora is the single worst invasive that I have to deal with because of its rose-like thorny branches. The toothed leaves and red hips further aid in identification. On my land, I’ve treated plants that were growing more than 10 feet tall and prospering in clumps that were just as wide across. The monoculture tendency is another strike against this species.
I didn’t discover Oriental bittersweet on my land until two years ago when a forester pointed it out. This was another case of an invasive hiding in plain sight, as I have now had to cut this flora in several places. Celastrus orbiculatus often grows as a long, ropey vine that can climb a tree 60 feet or more. The bark is very rough and a vine can be 4 or more inches wide. Glossy leaves and orange berries help to further identify bittersweet.
Joe Rossetti and Lori Chamberlin, forest health manager for the VDOF, suggest two methods that are typically used for controlling invasive plants: cut-and-spray and hack-and-squirt. Both perform best with a triclopyr compound as the herbicide. Rossetti recommends that for cut-and-spray, land managers sever a tree or shrub as close to its base as possible. That way, the herbicide has less distance to travel before it reaches the roots.
Both individuals warn that several applications are often required before an invasive plant finally succumbs. For example, I often have to treat autumn olive three or four times before this hardy plant finally dies. Follow-up spraying also may be needed for any invasive because other plants may spring up later from the seed bank.
Rossetti offers the following tips for the hack-and-squirt method: “The hack part should be accomplished by a hatchet or similar tool cutting through the bark and into the first layer of wood,” he says. “If the cut is on a downward angle, it creates a cup that prevents the triclopyr from running down the sides of a tree. Also, the triclopyr should be water-based, not oil-based, so that the herbicide can be more easily absorbed.”
Controlling invasive flora is a never-ending task, but a necessary one to help our native plants and animals. Start now to have better wildlife habitat later.
- This article is featured in the East edition of the February 2024 issue of Game & Fish Magazine. Click to subscribe.