Bush Honeysuckle
Bush Honeysuckle (Lonicera maackii), also known as Amur honeysuckle, is one of the most destructive invasive species in the St. Louis region. The Garden recently created a new bush honeysuckle brochure to increase public awareness of this issue and encourage citizens of our region to take notice and take action. This page on invasive bush honeysuckle provides complimentary information for the brochure, including expanded content on its origins and impacts, detailed instructions for control, native plants that are similar in appearance, and suggested landscaping alternatives.
 
Honeysuckle History

Impacts of Invasion

Native Plant Diversity: Woodlands invaded by bush honeysuckle have dramatically reduced diversity and abundance of native plants compared to uninvaded woodlands (2, 3, 4), and severe infestations develop into impenetrable thickets in which native plants are almost completely eliminated.

Forest Health: Bush honeysuckle invasion also inhibits the survival and growth of tree seedlings in woodlands and forest (3, 5, 6), and even reduces the growth of mature canopy trees in hardwood forests (7). This invasion threatens the very future of Missouri’s forests, which will not persist if mature trees die without replacement. Approximately one-third of Missouri is covered by forested land, and the timber industry creates thousands of jobs and contributes about $3 billion each year to Missouri’s economy (8).

A Competitive Advantage: Bush honeysuckle is one of the first plants to leaf-out in the spring, and is among the very last to drop leaves in the fall. This gives it a competitive advantage and allows it to shade-out native vegetation (4). The roots, fruits, and leaves of bush honeysuckle contain chemical compounds that inhibit seed germination (9, 10, 11, 12), further threatening the persistence of native plant populations. 

Pollinators, Insects, and Amphibians: Many native insects require the presence of specific native plants to complete their lifecycle, such as the well-known dependence of Monarch butterflies on native milkweeds. Similarly, the larval host plants of the beautiful spicebush swallowtail are native spicebush (Lindera benzoin) and sassafras (Sassafras albidum). When native plants are displaced by bush honeysuckle invasion, this eliminates essential habitat for the insects that rely upon these native plants. The chemical composition of bush honeysuckle leaf-litter is different than native vegetation, which alters water chemistry and impacts native insect populations in streams (13). These changes in water chemistry also influence tadpole survival and lead to reduced amphibian diversity in honeysuckle infested habitats (14).

What about the birds?: Birds, especially American Robins, consume the fruits of bush honeysuckle and are the primary means of dispersal for perpetuating its invasion (15). However, don’t get the impression that bush honeysuckle is good for birds. Honeysuckle berries provide poor quality nutrition; they are high in sugary carbohydrates and low in desirable fats compared to many of the native plants displaced by their invasion (16). Furthermore, native songbird nests in bush honeysuckle experience higher nest predation and lower fledgling survival compared to nests in native shrubs (17, 18)

Human Health: A recent study by researchers at Washington University in Saint Louis found that bush honeysuckle infestation increases human exposure to Lyme disease and Ehrlichiosis (a tick-borne bacterial infection) by increasing the activity of the tick host, white-tailed deer (19). Another recent study from the University of Illinois found that the displacement of native shrubs by invasive bush honeysuckle altered water chemistry, which caused an increase in survival and abundance of the common house mosquito, the vector for West Nile Virus (20). Lastly, the berries of bush honeysuckle are reported to be mildly poisonous to humans (21).

Recreation:  Dense infestations of bush honeysuckle on public and private lands prevent the enjoyment of our woodlands and stream banks for hiking, cycling, horseback riding, birding, hunting and other outdoor recreation. These infestations form impenetrable thickets in the understory of once open native forests and grasslands, encroaching upon trails, and limiting visibility into the surrounding environment.

Habitat management for white-tail deer and other wildlife is an important consideration for many rural landowners and hunters. There is often confusion regarding the value of invasive bush honeysuckle for deer habitat. There is an unrelated shrub in the eastern and northern US has the common name Northern Bush Honeysuckle (Diervilla lonicera), which is one of the most important plants for deer forage in the regions where it occurs. Unlike the native shrub, which does not occur in Missouri, invasive bush honeysuckle is not a quality forage plant for whitetail deer. Although invasive bush honeysuckle can provide cover for deer, if low-density patches aren’t eradicated they will rapidly develop into impenetrable thickets that creates intolerable conditions for hunting. 

Bush Honeysuckle Removal and Control

When: Bush honeysuckle can be removed any time of the year. However, early spring and late fall are ideal for locating and removing this invasive shrub, since it has leaves when our native shrubs and trees do not. Once you develop an eye for the yellowish-green leaves of bush honeysuckle in late fall, this time of the year is ideal for detecting isolated shrubs and removing them before the infestation expands.

How: There are multiple effective methods of removing bush honeysuckle. Selecting the right approach depends upon a number of factors, such as the area covered by the invasion, the size of the plants to be removed, and your personal capabilities and preferences. These instructions are intended to provide homeowners and volunteers information necessary to take action against bush honeysuckle. Some additional methods for controlling large-scale infestations used by professional contractors and conservation organizations with highly specialized equipment and experience are not addressed.
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