Invasive Plant Corner – An Introduction

Jeff Nelson, KNPS Board Member

Anyone who is interested in native plants will soon come across the term “invasive.” Invasive species and habitat loss are the main causes of biodiversity loss and destruction of native plant species worldwide. Although most of us have a general sense of what is meant when a species is deemed invasive, there is also a lot of confusion as to what an invasive plant is, what it does, and what should be done about it.

Amur honeysuckle (Lonicera maackii)

With this introduction, we are beginning a series of articles about invasive plants. In this first article we will define what is meant by an “invasive plant.” We will discuss why they are bad for our native ecosystems and discuss, in general, how they can be controlled. We will also point you towards online resources about invasive plants. In each subsequent article we will concentrate on a single type of invasive plant, giving information on how to identify the plant, where it came from, how it got here, the specific damage it does, how best to control it, and some native alternatives to plant when it has been removed.

What is an invasive plant?

So what exactly is an invasive plant species? In 1999, President Clinton signed an executive order creating the National Invasive Species Council as part of the Department of Interior with the mission “to sustain and expand Federal efforts to safeguard interests of the United States by preventing, eradicating, and controlling invasive species, as well as restoring ecosystems and other assets impacted by invasive species.” Within the executive order, an invasive species was defined as “a species that is non-native (or alien) to the ecosystem under consideration; and, whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” This original definition encompassed economic harm as a factor so as to include many agricultural weeds. Many of those agricultural weeds cause little, if any, harm to native plants and native plant communities. A better definition for an invasive species from our perspective is:

“An invasive plant is one that is both non-native to the eco-system under consideration and able to establish on many sites, grow quickly, and spread to the point of disrupting plant communities or ecosystems.”

Notice that there are two parts to this definition and both must be true for a plant to be considered invasive. Often in groups on the Internet you will see people call aggressively growing native species, particularly ones that spread rapidly in a garden, “invasive.” Using the term in that way dilutes the meaning and can take the focus off of truly damaging non-natives. A good term to use for native species that quickly grow in gardens or other disturbed areas is “opportunistic”. An opportunistic native plant is “a plant that is able to take advantage of disturbance to the soil or existing vegetation to spread quickly and out-compete the other plants on the disturbed site. “

Of course, this discussion raises the question of what is a native plant? A good definition that I use is:

“A plant that is a part of the balance of nature that has developed over hundreds or thousands of years in a particular region or ecosystem. Only plants found in this country before European settlement are considered to be native to the United States. The word native should always be used with a geographic or ecosystem qualifier (e.g. ‘native to wetlands in the Southeast US’).”

Why are invasive plants bad?

The best listing of the problems resulting from invasive plants was recently published by the US Forest Service:

“What are the impacts of invasive plant species?
  • Invasive species have contributed to the decline of 42% of U.S. endangered and threatened species, and for 18% of U.S. endangered or threatened species, invasives are the main cause of their decline.
  • Invasive species compete directly with native species for moisture, sunlight, nutrients, and space.
  • Overall plant diversity can be decreased
  • Establishment and spread of invasive species can degrade wildlife habitat
  • Results in poor quality agriculture lands
  • Degraded water quality
  • Increased soil erosion
  • Decreased recreation opportunities”

How can invasive plants be controlled?

Although the damage to native plant communities by invasive species can be great, many plant invasions can be reversed, halted or slowed, and in certain situations, even badly infested areas can be restored to healthy systems dominated by native species. Every management situation will be different. If a landowner has invasive species on her land, several questions need to be considered before deciding on a plan of control:

  • What is the species that is invading the space?
    A positive ID of the invader is an absolute must before beginning to control the infestation. In subsequent articles we will give tips for identifying many of the most common invasive species in Kentucky.
  • What is the size of the infestation?
    One or two bush honeysuckle plants are dealt with very differently than hundreds of square feet of wintercreeper.
  • What is the native biodiversity where the invasive species is?
    If there are lots of native plants existing in the area around the invasive plant, your approach to control must be done carefully and precisely. If there is a near mono-crop of invasive plants the control techniques used can be more aggressive.
  • What is the nature of the habitat that has been invaded?
    Not all potential control techniques are suitable for every habitat. Is there one or more other invasive species present that could reinvade the areas from which you are removing a target plants? Are you working in a forest or woodland, or a field? If you disturb soils, are they highly erodible? Are you working on flat ground or on slopes? Are you removing invasive species from wet sites or areas near water? Fields may be reinvaded by another species more quickly than forest land. Upland sites away from water tend to be less sensitive than sites along creeks or wetlands. In general, but not always, aggressive methods of control are more tolerated on upland sites. If one chooses to use herbicide, only some may be used in and around water.
  • Do you have the resources available for the size of the project?
    Time, equipment, chemicals, personal protective equipment, etc.

Once the questions above have been answered you need to consider the actual techniques that will be used to remove the invasive species. Often more than one technique should be used. No one technique is right for every invasive species removal project. They all have pros and cons that must be considered in light of the particular project.

An excellent discussion of the techniques used in invasive plant management is the Weed Control Methods Handbook: Tools & Techniques for Use in Natural Areas. All of the techniques mentioned below are discussed in depth. A very useful part of the book is the in-depth discussion of 11 types of herbicide commonly used in management projects.

  • Manual and mechanical techniques
    Techniques such as pulling, cutting, and otherwise damaging plants, may be used to control some invasive plants, particularly if the population is relatively small.
  • Grazing
    Grazing can either promote or reduce weed abundance at a particular site. By itself, grazing will rarely, if ever, completely eradicate invasive plants. However, when grazing treatments are combined with other control techniques, such as herbicides or biocontrol, severe infestations can be reduced and small infestations may be eliminated.
  • Prescribed fire
    Prescribed fire is primarily done to promote the germination and growth of native species in an area. By itself, fire can control some invasive species, although it can also promote the growth of some invasive species.
  • Biological control
    Biological control is the use of animals, fungi, or other microbes to feed upon, parasitize, or otherwise interfere with a targeted pest species. Successful biocontrol programs usually significantly reduce the abundance of the pest, but in some cases, they simply prevent the damage caused by the pest.
  • Herbicides
    “Before using herbicides carefully consider the overall impacts of herbicide use on your conservation targets, other native species, and the ecological system. Base all decisions whether to control weeds, and whether to use herbicides instead of other methods, on the conservation targets and management goals for the site. In addition, the health and safety of applicators and others in the vicinity must be considered BEFORE pesticides are applied. Simply put, one should be confident that the proposed herbicide will do more conservation good than harm and not endanger the health of the applicators or others in the area.” – Weed Control Methods Handbook.

Online resources

There are many online resources for learning about invasive plants and invasive plant control. This list is of some that I have found useful.

Heavenly bamboo (Nandina domestica)

By Heather Doolin, Office of Kentucky Nature Preserves

Heavenly bamboo (Nandina domestica), also commonly called sacred bamboo, is an evergreen shrub, vaguely resembling bamboo.  Heavenly bamboo began its journey in North America as an ornamental plant, escaping cultivation and invading forests of ten southern states, Kentucky being included in those affected.

Description

One may notice heavenly bamboo throughout many of the plant communities within the southeastern United States, its highest densities reported in upland mixed forests, floodplain forests, and slope woodlands (Stone 2009).  Throughout south-central Kentucky, you might notice this plant in a neighbor’s front yard, as a decorative plant in front of many businesses, and in the forested areas surrounding our beautiful limestone slope glades.

Distinct Features

Perhaps the most distinguishing characteristic of heavenly bamboo are its berries.  They are a striking red, occurring in clusters (Flora 2009).  These berries most closely resemble yaupon holly (Ilex vomitoria), but tend to be a deeper red, nearing purple.

Heavenly bamboo berries. Common License.

Appearance

Heavenly bamboo is an evergreen shrub displaying multiple, unbranched, slender stems.  It grows to approximately seven feet tall and is glabrous (Godfrey 1988).  When flowering, you will notice white flowers in terminal clusters, fruiting later into red berries containing one to three seeds each (Miller 2003).

Leaves

The leaves of heavenly bamboo are compound and alternate.  They are near the ends of stems and are approximately 20 inches long and 30 inches wide.  Their appearance is glabrous and medium green in color. (Godfrey 1988)

Heavenly bamboo. Common License.

Habitat

As mentioned previously, heavenly bamboo in woodlands and forests varying from upland to slope to floodplain (Stone 2009).  This plant seems to favor shaded areas under well-established forests with minimum to moderate understory.

Where Found in US

While the state most populated by heavenly bamboo in a 2008 study was Tennessee, several other states throughout the southeastern US are affected by this invasive species, Kentucky being one of them. 

How it Got Here

In the early 1800’s, heavenly bamboo was introduced to North America from Asia through cultivation for use as an ornamental plant.  Heavenly bamboo escaped cultivation and found its way into healthy woodlands and forests, likely being dispersed by way of birds and mammals. 

Ecological Impacts

While heavenly bamboo is not as populous in Kentucky as an invasive species as it is in other southeastern states, it is already displaying many ecological impacts.  The berries of heavenly bamboo, while nutritious to some wildlife, can be toxic, along with the leaves of the plant to other animals, particularly ruminants (Burrows 1983).  The ability of heavenly bamboo to establish itself quickly and vigorously in native communities puts native species at risk.  In south-central Kentucky, one particular habitat that is uniquely at risk are glade communities with glade privet (Forestiera ligustrina).

How to Control

The two most useful methods of control for heavenly bamboo are manual removal and herbicide.

Manual

Hand pulling may be laborious but is effective in smaller heavenly bamboo stems.  Once the plant grows larger, it can be difficult to remove by pulling up the entirety of the root system.  Removing the root system is of utmost importance as the plant can recolonize if root fragments remain.  The best time to remove heavenly bamboo is prior to fruiting, preferably before autumn.  Following up and remaining vigilant is important with a manual method of treatment.

Herbicides

Herbicides are a useful method in the removal of heavenly bamboo.  A cut stump method, spraying or sponge-application of the stump with a 20% solution of glyphosate, or a brush-control herbicide containing triclopyr can be useful.  Application is best in late summer to early autumn, during heavenly bamboo’s dormant season.  As with manual removal, be sure to follow up as resprouting can always occur.  A final note is that glyphosate is a non-selective herbicide and as such, care should be taken with application in sensitive habitats.

CITATIONS

Stone, Katharine R. 2009. Nandina domestica. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/plants/shrub/nandom/all.html

Flora of North America Association. 2009. Flora of North America: The flora. Flora of North America Association (Producer). Available: http://www.fna.org/FNA

Godfrey, Robert K. 1988. Trees, shrubs, and woody vines of northern Florida and adjacent Georgia and Alabama. Athens, GA: The University of Georgia Press. 734 p.

Miller, James H. 2003. Nonnative invasive plants of southern forests: A field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p. Available online: http://www.srs.fs.usda.gov/pubs/gtr/gtr_srs062/

Burrows, G. E.; Tyrl, R. J. 1983. Ornamental plants potentially hazardous to cattle. The Bovine Practitioner. 18: 188-194.

Heather Drake is a natural lands manager for the Office of Kentucky Nature Preserves. She is from the mountains of Virginia, for which she credits her love of the outdoors. Heather has a B.S. in Environmental Science from Georgetown College and a M.E.M in Water Resource Management and M.F. in Forest Management from Duke University. Her current work focus is in managing preserves at the habitat level, controlling for invasive species, utilizing prescribed burns, and habitat restoration. Heather enjoys learning about native plants and their medicinal uses, new management strategies, and land use history.

Invasive Plant Corner: Lesser Celandine (Ficaria verna)

By Deborah White, Kentucky Native Plant Society Board

By the end of winter, we are looking for any hope of spring, any bright color in the landscape we can find. When you see a pretty yellow flower in late winter, check to see if it is lesser celandine (Ficaria verna) before you get excited.

Description

Ficaria verna: Common License

The leaves of this invasive plant emerge in winter, and they cover the ground quickly, outcompeting many native plants. This pest plant has a single yellow flower at the end of a stem. It is closely related to buttercups (its former name is Ranunculus ficaria, and sometimes it is called fig buttercup) and, like buttercups, the flower has many stamens. There are seven to thirteen flower petals. The leaves are medium to dark green, generally heart-shaped and not lobed with wavy edges that have smooth or rounded teeth. Also, the small bulbils at the base of the plant will help identify it (see also the control section as these bulbils allow this weed to spread).

Habitat

Lesser celandine grows in riparian areas like stream banks and adjacent flat moist areas, shady woods and even lawns. Lesser celandine is found in the eastern United States, west from Texas and Missouri, as well as Washington and Oregon on the west coast.

Lesser celandine covered these shaded woods at UK Arboretum in 2019. Photo by Emily Ellingson.

How it Got Here

Lesser celandine is native to Europe, Asia and Africa. Introduced to the United States for horticultural use as a border plant, this weedy invasive is, unfortunately, still being sold. It easily escapes from gardens to nearby forests. The fingerlike bulbils and fruit can be spread by flooding, or any movement from one habitat to another, even mowing.

Lesser celandine in the United State; blue states show its presence. Map by NRCS.

Ecological Impacts

Lesser celandine can quickly form a blanket across the ground in natural areas. It crowds out native plants and depresses their reproduction. Like other invasive weeds, the elements that control these plants in their native range, whether fungus, animals or other biological controls, are absent, leaving this plant free to increase, unchallenged.

How to Control

Small infestations may be removed by pulling the plants by hand, but all plant parts must be removed to be effective. The roots and bulbils easily fall from the plants and then establish new plants!

It is also possible that covering the plants with black plastic to solarize, or heat up the soil can help kill the vegetative structures and root systems of the plants. This would be appropriate where lesser celandine is abundant.

Studies show spraying with herbicide is effective, especially if applied before other plants have emerged. Glyphosate has been used to control lesser celandine but be aware that it is not appropriate for use near aquatic habitats. A 2.5% solution may be applied when it is at least 50 degrees Fahrenheit–being extra careful to spray only lesser celandine because the herbicide will affect any plant it contacts. It may take two or even three applications and future monitoring to eliminate the plants. You will be helping our natural flora by battling this yellow invader!

References

Aulakh, Dr. Jatinder S. Lesser Celandine (Ficaria verna Huds.) Identification and Management. Connecticut Agricultural Experiment Station.

Plants for a Future. Accessed 4/2/2021 Ficaria verna https://pfaf.org/user/Plant.aspx?LatinName=Ficaria+verna

Washington State Noxious Weed Board. Lesser Celandine. https://www.nwcb.wa.gov/weeds/lesser-celandine-1

Invasive Plant Corner: Lesser Celandine (Ficaria verna)

At the end of winter we are looking for any hope of spring, any bright color in the landscape we can find. When you see a pretty yellow flower in late winter, check whether it is lesser celandine (Ficaria verna) before you get excited.

Deborah has been a botanist for the Kentucky Office of Nature Preserves and Florida state plant conservation programs.

Invasive Plant Corner – Japanese Stiltgrass (Microstegium vimineum)

By Nick Koenig

Japanese Stiltgrass (Microstegium vimineum), often called Stiltgrass or most commonly Microstegium, is a shade tolerant grass in the Poaceae/Grass plant family. This is the second most biodiverse plant family in Kentucky right behind Asteraceae/Sunflower family. Given the massive number of species in the family and the distinctness between members in the family, recognizing Microstegium can be tricky but I hope to help so that native plant lovers can start to remove this species from their landscape!

Description

It is likely if you have hiked along a creek in a disturbed area or walked along a road, you have probably come across Japanese Stiltgrass and thought nothing of it. However, this should be of great concern to landowners/land managers/native plant enthusiast. Once you can competently identify the next patch of Microstegium you come across, you can help eradicate it from the area.

DISTINCT FEATURES

By far, the most distinctive feature for Microstegium that I use in field identification is the faint silver line running down the middle vein of the leaf. This characteristic is not as prominent and distinctive among any other native grasses in Kentucky.

Silver line on leaf of Microstegium (picture taken by Nick Koenig).

APPEARANCE

Japanese Stiltgrass is a “weak-stemmed annual, branching, decumbent [running along the ground then rising up], rooting at the lower nodes [points where leaves or stems come out].” (Weakley 2015).

Picture of a few Microstegium shoots prior to flowering and seeding (picture provided by Jeff Nelson).

LEAVES

As described in the Flora of the Southeast (Weakley), the leaves are ovate-lanceolate (meaning oval and much longer than wide, roughly 2.5-7 times longer than wide ), 2-10 cm long tapering at the base.

HABITAT

Microstegium can most likely be found in “disturbed areas, colonizing moist, rich soil, especially in floodplains” such as along a creek bank where it is often found (Weakley 2015). Due to the Japanese Stiltgrass’s ability of being shade-tolerant, the species can make deep incursions in a forested area.

Example of Microstegium vimineum (Japanese Stiltgrass) growing alongside the beautiful native, Impatiens capensis (Spotted Touch-Me-Not, Orange Jewelweed; picture provided by Jeff Nelson).
Continue reading Invasive Plant Corner – Japanese Stiltgrass (Microstegium vimineum) →

Ecological Effects of Amur Honeysuckle Infestations

By David D. Taylor

This article expands on Invasive Plant Corner – Bush Honeysuckle (Lonicera Spp.), in the April 2020 issue.

Amur honeysuckle (Lonicera maackii) is the most widespread and arguably the most invasive of the nonnative invasive honeysuckle shrubs in Kentucky. Jeff Nelson’s article on Amur honeysuckle provides a general overview of the species. This article provides some details as to why this species is so invasive and why is an ecologically undesirable species.

Amur honeysuckle, native to central and northeastern China, Japan (rare), Korea, and far eastern Russia, occurs as an understory shrub in open hardwood and mixed hardwood-conifer forest consisting of oaks, elms and other hardwoods and fir, spruce and hemlock. It is also known from and more common in riparian and scrub communities (Luken and Thieret 1996). It grows as scattered individual shrubs or small clumps, not unlike viburnums do in Kentucky. Large, dense stands do not typically occur, but in open, riparian areas it can be weedy. In its native range, individuals typically do not exceed 4 inches diameter and 20 feet tall (Yang et al. 2011). In Kentucky, the species is often an understory shrub in open forest, but forms dense thickets at forest edge, along fence rows and in open areas. It grows larger here as well, to 6 inches diameter and 30 feet tall (personal observation).

Large Amur honeysuckle, two stems 5 inches or greater in diameter.
29 April 2020. 
Photo by David Taylor

This shrub leaves out early in spring, often breaking bud in mid-March, long before native trees and shrubs. By mid-April of most years, leaves are fully expanded, and the shrubs are actively growing. In the fall, Amur honeysuckle typically senesces (leaves turn yellow and drop) in late October to mid-November, and sometimes not until early December. Native trees and shrubs typically break bud late March to mid-April and do not fully expand until early May. In eastern Kentucky, they are actively dropping their leaves by mid- to late October in most years. The extra 5-8 weeks of photosynthetic activity in the honeysuckle allows it to store additional energy giving it an edge over native species (McEwan et al. 2009). It is also somewhat tolerant of late freezes. Both promote its invasive nature.

Tall Amur honeysuckle, approximately 27 feet tall. 
29 April 2020. 
Photo by David Taylor

While Amur honeysuckle grows better in full sun (Luken 1995), it is known to survive in 1 percent of full sunlight in the heavy shade of trees (Luken et al. 1997a). The native spring flowering spice bush (Lindera benzoin) by comparison, requires about 25 % of full sun to survive (Luken et al. 1997a). Forest grown Amur honeysuckle under heavy shade tends to produce few stems which grow upward toward light specks. They tend not to have much branching, nor do they attain much diameter. In the open, individual shrubs produce numerous stems and branching is extensive. Maximum diameters are obtained in the open (Luken et al 1995a). Overtopped Amur honeysuckle shrubs respond with the production of long, upright stems that seek light. Honeysuckle in open forest may branch extensively and produce heavy shade.

Continue reading Ecological Effects of Amur Honeysuckle Infestations →

Invasive Plant Corner – Bush Honeysuckle (Lonicera spp.)

By Susan Harkins, Jeff Nelson, & David Taylor

In any list of the top five invasive plant threats to Kentucky’s native plant communities, bush honeysuckle would appear in all of them. There are three species of bush honeysuckle commonly found in Kentucky: Amur (Lonicera maackii), Morrow’s (L. morrowii), and Tartarian (L. tatarica). Another two, Standish’s (L. standishii) and Fragrant (L. fragrantissima), are less common. All are members of the Caprifoliaceae (Honeysuckle) family. All of them are similar in appearance and effect. Because of the similarities and because it is the most widespread of the bush honeysuckles, the rest of this article will concentrate on Amur honeysuckle. There are slight differences in appearance between Amur honeysuckle and the other bush honeysuckles, but in general they are similar enough to easily recognize.

Description

Most of us have seen invasive Lonicera while hiking or even around town. They’re everywhere. Knowing how to identify them is the first step to removing them.

Appearance

Cross section of bush honeysuckle stem

Lonicera maackii is a woody perennial shrub that, at maturity, is typically 6’-20’ tall, but occasionally taller. The shrubs are upright and deciduous. Although deciduous, in Kentucky the bush honeysuckles retain their leaves longer in the fall than native shrubs and leaf out earlier in the spring. The pith of mature stems is hollow and white or tan.

Leaves and flowers of Lonicera maackii

Leaves

Leaves are opposite, ovate with a tapered tip, lightly pubescent, and up to 3½ in. long.

Flowers

Flowers are paired, tubular, white to pinkish, fading to yellow, less than 1 in. long, borne from leaf axils, five petals, upper 4 fused.

Fruit of Lonicera maackii
Fruits

Fruit

Fruits are red to orange-red berries produced in late summer and persist through the winter. This shrub can bear fruit when it is as young as 3 to 5 years old.

Habitat

Amur honeysuckle is one of the most common and invasive bush honeysuckles found in Kentucky. It occurs in most states in the eastern U.S. except for Minnesota, Maine and Florida and has been reported to be invasive in many. It is adaptable to a range of conditions from sun to deep shade and wet to dry. It occurs in disturbed habitats including forest edges, forest interiors, floodplains, old fields, pastures, and roadsides. Disturbance increases the likelihood of invasion. Amur honeysuckle grows especially well on calcareous soils.

It spreads by fruits that are abundant and highly attractive to birds that consume them and defecate the seeds in new locations. Vegetative sprouting aids in the local spread and persistence. It does not generally root sprout.

Where Found in KY

The bush honeysuckles are found across Kentucky, in any just about any suitable habitat.

Lonicera maackii distribution map

How it Got Here

NE China, Japan, Korea, and Russian Far East

Amur honeysuckle was imported as an ornamental into New York in 1898 through the New York Botanical Garden. It has been widely planted for wildlife cover and soil erosion control but long ago escaped from plantings and began reproducing on its own and spreading into natural areas. It was originally planted in the U.S. as an ornamental shrub, but it quickly escaped gardens and naturalized throughout much of the eastern U.S. to the Great Plains into a variety of sites including roadsides and railroads, woodland borders, some forests, fields, unused or disturbed lands and yard edges. Once spread into the wild, it can form dense, shrubby, understory colonies that eliminate native woody and herbaceous plants. Amur honeysuckle flowers late April to June, and the white and yellowish flowers produce red berries in the fall that may contain more than 1 million seeds on mature (25-year-old), 20-foot tall plants. The seeds are consumed and spread by some species of songbirds generally after other more nutritious native foods are gone. As with many invasive species, bush honeysuckle can grow and thrive over a wide range of habitats. In Kentucky, all shrub honeysuckles are exotic and invasive.

Ecological Impacts

Amur honeysuckle impedes reforestation of cut or disturbed areas and prevents reestablishment of native plants. It leaves out earlier than most natives and form dense thickets too shady for most native species. Additionally, researchers in the Midwest found increased nest predation of robins using Amur honeysuckle as a result of plant structure, which facilitates access to nests by predators such as snakes. While the carbohydrate-rich fruits of exotic honeysuckles provide some nutrition for birds and rodents in winter, they do not compare to the lipid-rich fruits of native species that provide greater energy to sustain migrating birds. Few insects feed on the plant, but birds and mammals spread the fruits. It may have allelopathic effects on neighboring plant species.

How to Control

There are several methods for controlling–removing–invasive bush honeysuckle. They all take tenacity and a bit of effort.

Manual/Mechanical

Young plants can be pulled by hand. Larger plants either can be pulled using a weed lever-type tool or cutting repeatedly for a few years.

Grazing

Goats are particularly fond of this this plant and will rapidly consume young plants and any they can climb into. Cutting larger plants and allowing goats to eat the sprouts can be effective, but could take several years depending on what root reserves the plants have.

Fire

Fire will kill seedlings. Larger plants may be top killed, but mostly likely will sprout from the base. The sprouts must be treated as well.

Biological Control

No biological controls are currently available for this plant. However, the honeysuckle leaf blight fungus (Insolibasidium deformans) has been found in both northern and central Kentucky. It has been observed severely injuring and killing open grown populations of Amur honeysuckle.

Herbicides

Appropriate herbicides, when applied correctly, are known to effectively control bush honeysuckle through cut stem, foliar, and bark applications. Contact your local Extension Office, or Natural Resources Conservation Service office or Kentucky Department of Fish and Wildlife private lands biologist for recommendations concerning herbicide choice, application rate and application method that best suit your conditions and needs.

Native Alternatives

Lonicera simpervirens

Whether you were raised in Kentucky or you’re an implant, you’ve probably enjoyed the luscious fragrance of honeysuckle as the sun begins to set. It isn’t quite jasmine; not quite gardenia; it’s unique, powerful, and intoxicating. It’s easy to understand why homeowners planted the invasive Loniceras. Where alternatives are concerned, there’s good and bad news. The good news is that we have native Lonicera. The bad news is, they are pollinated by bees and hummingbirds, so the scent is weak. In comparison, the invasive is pollinated by moths—hence the strong evening scent. What the natives lack in fragrance, they make up for in color (to attract the bees and hummingbirds).

Across North America, there are over a dozen native Lonicera species. In Kentucky, we have one to consider: Lonicera sempervirens L., trumpet or coral honeysuckle. It prefers moist soil and full sun, but tolerates shade, although, in the shade, it will produce blooms for a shorter period of time.

Lonicera simpervirens

Lonicera sempervirens is one of the longest-blooming natives available to us here in Kentucky. It’s brilliant red trumpet-shaped flowers spring into life as early as late March and persist into fall, even early winter. Its leaves often persist throughout the cold, giving a bit of winter interest. The base is woody and gnarly (interesting to look at) but the vigorous upper vines are gentle and easily coiffed if necessary. You can train it to look like a bush if you prefer.

Unfortunately, Lonicera sempervirens won’t gift you with a glorious fragrance. If that’s what you’re after, consider Wisteria frutescens (L.) Poir., Kentucky wisteria. Similar to Lonicera, you’ll get the most blooms in full sun, but it will tolerate shade. It’ll grow in the same type of moist soil as well. It’s purple blooms are larger and showier, and it’ll grow a bit larger than Lonicera, but the native species isn’t as harmful to structures as the invasive Wisteria floribunda and Wisteria sinensis. Wisteria is stronger and woodier than Lonicera so it will require a stronger support, such as a strong arbor. (Resist growing it along a fence or up the side of your house because it’s difficult to remove.) It’s also more assertive than the native Lonicera, so it might require a bit more care to keep it under control.

There are several other species of Lonicera listed as native to Kentucky by the USDA plants database, but they’re rare or endangered. It’s unlikely you will find one in a reputable nursery.

For other alternatives to bush honeysuckle, check out the brochure, Kentucky’s Native Alternatives to Invasive Plants.

Photo Credits: Lonicera by common license thanks to Biodiversity Heritage Library.

Information sources:

Boyce, R.L., S.N. Brossart, L.A. Bryant, L.A. Fehrenbach, R. Hetzer, J.E. Holt, B. Parr, Z. Poynter, C. Schumacher, S.N. Stonebraker, M.D. Thatcher, and M. Vater. 2004. The beginning of the end? Extensive dieback of an open-grown Amur honeysuckle stand in northern Kentucky, USA. Biol. Invasions 16:2017-2023. DOI 10.1017/s10530-014-0656-7.

Lonicera maackii – Invasive Plant Atlas – . Accessed April 2020.