Amur Honeysuckle:  Scourge of our forests

Honeysuckle Eradicated

Honeysuckle has been eradicated

Whether you are a landowner with an expansive forest, a homeowner on a residential street with a small yard, a tenant, old or young, you should have the Amur (or bush) honeysuckle on your personal plant blacklist.  This species is an insidious threat to our forests not only here in Fort Thomas but throughout northern Kentucky.  It should not be considered an ornamental landscape item, a specimen tree, windbreak or a screen.  It is the cockroach of our forests and should be removed forever.

Although the term ‘bush honeysuckle’ encompasses many different species, all are exotic and invasive in North America. The most common species in Kentucky, Amur honeysuckle, is native to northern China, Korea and parts of Japan. It was first introduced to the United States in 1897 for use in ornamental plantings. In the 1960s and 1970s, it was even recommended for conservation and wildlife use, though now it is recognized that its berries are not as nutritious for wildlife as native fruits are. The plant reproduces through seed; a mature plant can produce approximately one million berries in one season. And evidence strongly suggests that Amur honeysuckle produces chemicals detrimental to native plant growth. This is a condition known as allelopathy. All of these factors make it a threat to native woodlands.

Grows Anywhere

Because Amur honeysuckle can grow in a range of habitats and light conditions, the entire state is susceptible to invasion from this species, which is found in greatest abundance in north and central Kentucky.  It is among the first to emerge in spring and the last to lose its leaves in the fall, making it fairly easy to identify at those times of year.  If you take a drive along highways that afford good views of the forests you can easily spot the vast understory of honeysuckle and see firsthand how pervasive it is.  It can rise to a height of 15 feet or more with several arching branches that provide a dense shade to the forest floor stifling growth of native wildflowers and forest regeneration.

The biggest effect is these invasive plants squeeze out our native plants to a point where our native woodlands cannot regenerate. The problem doesn’t only include loss of native plant species. It directly affects native wildlife and impacts the state’s economy. Wildlife contributes approximately $2 billion to Kentucky’s economy, so the loss of their habitat, and consequently their disappearance, has a big economic impact, according to a study at the University of Kentucky College of Agriculture.  Another study in the magazine National Wildlife shows the effect of honeysuckle on certain bird species.

We have a program

The Fort Thomas Forest Conservancy has chosen honeysuckle eradication as one of its focus areas, because bush honeysuckle is so prevalent in our forests and open spaces.  The forests remain attractive and for the most part are healthy, but there is no doubt that over time they face a serious threat from invasive species.  We launched a program in the fall of 2009 to educate our community about invasive species and to organize events  designed to teach the methods of honeysuckle eradication.

Our first eradication event was in November, 2009, along the Fort Thomas Landmark Tree Trail in Tower Park.  The trail is easily accessible, widely known and heavily traveled and had a fairly high density of honeysuckle along most of its length that obstructed the view in the forest. Clearing the trail of honeysuckle would be important both for ecological and aesthetic reasons.  It attracted nearly 50 volunteers, armed with handsaws, chainsaws, loppers, sprayers and herbicide.  We divided them into teams that spread out along one half of the mile-long trail.  In three hours on a Saturday morning we cleared a swath 50 feet wide along the trail using techniques taught us by board member Mark Leopold of the Northern Kentucky University’s Center for Applied Ecology.

Scope and Technique

We use the “cut stump” treatment method in our eradication program.  First, we use either a bow saw or chainsaw to cut the tree as low as possible to the ground to avoid trip hazards.  Then we apply a herbicide solution (20.5 percent glyphosate to water) to the stump within 3 minutes of cutting.  You can use a backpack sprayer or utility spray bottle for spray applications or a wick applicator, lab wash bottle, or paintbrush for small stems.  Only the cambium layer of the stump needs to be sprayed, although on smaller trees it is difficult to limit exposure to that layer.  The cambium layer is just inside the bark layer and is the only living part of the stem.  Finally, you will want to render the fallen trees, using loppers or snapping off the branches, as flat as possible and over time they will dry out and eventually return to the earth.

If you have any questions about the ways and means of honeysuckle eradication, please send us a note.