Honeysuckle Management
Bush honeysuckle is a pervasive invader of our native ecosystems. It permeates our beautiful remnant oak savannas and oak/hickory woods in the Driftless Area, degrading these habitats and causing problems for our wildlife. However, removing them is intensely gratifying! And we have good field science and biological science available. With these, we can make good decisions about what management combinations to employ while protecting our time and money. I’m all about that!
A Bit of History
How did honeysuckle come to be in the US? USDA Soil Conservation Service (SCS) promoted bush honeysuckle from 1960s to 1984 for habitat improvement (Rich 2000). Even after honeysuckle’s high reproductive capacity was documented, the United States Department of Agriculture Soil Conservation Service (USDA SCS; now the Natural Resource Conservation Service [NRCS]), sponsored programs for property owners to use the invasive bush honeysuckle for soil stabilization, site reclamation, and wildlife habitat improvement. From the 1960s to the late 1980s, the SCS operated a breeding improvement program to develop improved cultivars of the invasive bush honeysuckle. I really hate that once again, our government, who is supposed to steward our natural environment, demonstrates unwise and reckless decision making.
Fortunately, since 1996, the NRCS has changed their policies and now funds cost-share programs for property owners to remove bush honeysuckle and other invasive plants (Krochmal 2024). This is good news, yet until it becomes a prohibited species with full enforcement of that statute, unmanaged habitats will continue to degrade. For those responsible land stewards, it is difficult to eradicate honeysuckle if nearby areas are filled with it (Rich 2000). But if we keep on keeping on, persistence will pay off!
A growing season and a dormant season photo of a fairly large honeysuckle bush. They don’t have much basal volume so once chainsawed, it opens the space tremendously.
A Little about Bush Honeysuckle
Bush honeysuckle is reproductively mature at 3-8 years (Hogan et al. 2023). Once we have cleared an area of the overgrown honeysuckle and other invasive woody species, this gives us time to get the resprouts before the honeysuckle produces fruits.
When honeysuckle establishes dense thickets, the ground beneath it lacks leaf litter because honeysuckle leaves decompose quickly, leaving bare ground (Krochmal 2024). As I type this, it reminds me of a conversation with an “expert” about restoring our oak savanna. Their first piece of advice was to “run a burn through it.” I chuckled as it was clear this “expert” had no experience with bush honeysuckle and its biology. Not only was there no fuel to carry a fire, but bush honeysuckle readily resprouts from roots when the aboveground vegetation is damaged or removed (Hogan et al. 2023, Rich 2000).
The area before clearing. It’s not possible to “run a burn through” this.
After clearing the honeysuckle, the area is bare.
A bit more research on the plants’ biology reveals that microbial activity is reduced in the soil but increased within the rhizosphere (the area around the roots) (Krochmal 2024, Frank et al. 2018). Could this be due to the allelopathic chemicals it exudes (Hogan et al. 2023)? I continue to search for information on these soil processes because both would negatively affect germination and survival of native plants.
The dense canopy that honeysuckle creates can’t be ignored. It affects rainfall penetration. This reduces hydrologic recharge and alters nutrient cycling (Medley and Mohrman no date). It’s probable that other invasive species have this effect as well.
Seeds
Bush honeysuckle produces abundant fruit, which is dispersed by birds and other wildlife (Richburg 2005, Hogan et al. 2023). With tongue-in-cheek, we call these “gifts.”
The seeds are encased in a small red or yellow fruit. They are hardy little things! Smaller than 4mm, the seeds remain viable once passed through a bird or mammal’s digestive system (Knapp et al. 2023). The good news is the seed bank isn’t long lived — maybe 2-3 years (Hogan et al. 2023). Generally speaking, plants with high germination rates typically have short-lived seed banks (Rich 2000).
Seeds can be killed by fire, but they would need to be setting on the soil surface. Seeds buried in the soil up to 2cm (about ¾”) deep are protected (Guthrie et al. 2016). I wonder how long it would take a seed to become buried that deep?
Source: Invasive Species Center
Loss of Wildlife Diversity
Source: Friends of Mississippi River
I’m often asked why invasives are problems. Don’t they offer food and shelter for animals? Invasive bush honeysuckle shrubs outcompete and shade out native plants. Insects in our region haven’t evolved with these non-native plants and therefore don’t use them as host plants to rear their young. As one example of a cascading effect, losing native plants and their different floral structures also reduce pollinator activity (Medley and Mohrman no date).
Birds nest in honeysuckle because they leaf out earlier than other shrubs; but these birds suffer greater predation because of their low growth stature. Nests in honeysuckle fledge 20% fewer birds than nests in native shrubs (Medley and Mohrman no date; Rich 2000). Invasive bush honeysuckles also reduce amphibian diversity or shift it to fewer species. Tree frogs seem not to be as affected by non-native bush honeysuckles (Medley and Mohrman no date; Watling et al. 2011).
So…How Do We Get Rid of It?
Like most every other invasive, no single control method will be effective. It requires a combination of management techniques and follow up is essential after any disturbance – fire, mowing, grazing.
The link to the right will provide detailed information on the 3 herbicide technique methods discussed below. We’ll also discuss hand pulling and because of time constraints, we’ll look at a couple of triage methods.
We have found using a 20% trichlopyr mix (Garlon 4 or Element 4) in bark oil to be the most effective for all treatment methods. If you purchase the 2 gal short fill of bark oil blue, you can mix the 64oz of trichlopyr into the 2 gal short fill and you’re ready to go.
We have found this herbicide mix and the cut & treat method are effective any time of the year. Ignore those who say there’s one season that is more effective than another. Basically, the best time to remove invasives is when you have time.
Herbicide – Cut & Treat Method
The cut-and-treat (C&T) method, combined with herbicide application, is widely regarded as the most effective approach for managing any invasive woody species (Medley and Mohrman, no date; Charton and Damschen, 2024). Our personal experience aligns with these findings.
Herbicide treatments alone have resulted in a 96.9% mortality rate of targeted plants (Hogan et al., 2023). Another study found C&T reduced the number of stems from 11,000 per acre to 9,500 (Schweitzer and Dey, 2020). The researchers noted that the smallest stems remained and were likely due to being overlooked (Schweitzer and Dey, 2020). Hey, we’re human. We should expect to miss stems. It highlights the importance of multi-year follow-up.
One advantage of the C&T method is it minimizes soil disturbance, which prevents encouraging the seed bank of honeysuckle and other invasive species to germinate and grow.
C&T can be performed at any time except when snow covers the land, as cutting needs to be done at ground level. The season of treatment does not appear to affect the overall success rate.
Jim herbiciding a stem after it was cut
Herbicide – Basal Bark method (Swiping or spraying)
Basal bark treatment killed 98.4% regardless of the season or the height of the honeysuckle (Hogan et al. 2023). If you use basal bark on large, sprawling adults, you may also choose to follow up by chainsaw removal of the sprawling dead limbs.
Herbicide – Foliar spraying method
Foliar herbicide of small shrubs might be easier than cutting and treating them but follow up remains essential to get the missed stems (Schweitzer and Dey 2020). This is not unusual! Three years of foliar treatment resulted in 2,700 stems per acre; the area began with 9,500 (Schweitzer and Dey 2020). If you are considering foliar treatment, be mindful that the overspray can cause collateral damage and will require more herbicide compared to basal bark or C&T methods.
Ultimately, the best time for treatment is when it fits your time and resources!
Hand pulling
Hand pulling is an effective technique when dealing with young and small honeysuckle plants (Rich, 2000). However, this method disturbs the soil, which may not be ideal depending on your ecosystem and management goals. Soil disturbance could encourage the germination of seeds from the invasive species’ seed bank, impacting the overall effectiveness of this method.
The left most photo shows a honeysuckle that is small enough to hand pull. The right most photo shows the extensive root system of that small bush. The red arrows are pointing to the various horizontal roots. It’s easy to see how this would disturb the soil although my photo wasn’t taken with that disturbance in the background.
2 Triage methods
When facing time constraint, we have found the need to triage an area. We do this so it doesn’t produce seed and continue to add to the seedbank. Once the labor-intensive work of cut & treat of the large shrubs is completed, but your time frame doesn’t allow for those little ones to be dealt with, there are a couple of methods that can buy you some time.
Depending on the topography of your land, mow the area then treat resprouts in 2-4 weeks. Or you can delay until early spring just as the vegetation begins to resprout and is in rosette form. Remember, bush honeysuckle greens up first!
If topography prevents mowing, a fall prescribed burn (assuming there is any fuel) gives you time to follow up in winter with basal bark herbicide or cut and treat of those charred, top killed stems; or you can wait until spring and spray resprouts.
What Doesn't Work and Why
Sometimes it’s as important to know what doesn’t work as what does. Knowing this along with the explanations for why they don’t work makes better use of our resources.
Cutting or grazing without herbicide
Chainsawing, cutting, mowing, or grazing without the use of herbicides doesn’t work well for managing bush honeysuckle due to its prolific resprouting capability (James et al., 2022; Schierenbeck, 2004). One study found that untreated stumps resulted in a 33% increase in stems per acre, from 12,600 to 16,700 stems (Schweitzer and Dey, 2020). This highlights the necessity of combining mechanical methods with herbicide treatments to effectively manage and control bush honeysuckle.
Fire without herbicide follow up
Prescribed fire is often used to control honeysuckle (and other invasive brush) even though research since 1980 has documented its ineffectiveness. Topkilling, the charring of aboveground stems, sounds lethal and when eyeballing the burned area, it appears lethal too. But our eyes can fool us. A distant eyeballing of charred stems isn’t sufficient. This can lead to a belief in fire’s effectiveness despite evidence to the contrary. Some of the smallest seedlings may die but there is a notable absence of detailed, quantitative research proving this (Riley 2013, Nuzzo 1997; Medley and Mohrman no date). Prescribed burns are generally not hot enough or reside long enough in one area to kill seedlings and impact their root systems (Hogan et al. 2023; Kline and McClintock 1992; Miller et al. 2017, Guthrie et al. 2016, Barden and Matthews 1980, Zouhar et al. 2008; Taylor and Midgley 2018, Mandle et al. 2011, Rebbeck 2012, Ward et al. 2013, Rivera 2021, Huebner 2006, Moser et al. 2016, Ashton et al. 2015).
Annually burning for 2-5 years “reduced its importance” but warned that bush honeysuckle often increases in abundance post fire because of resprouting (Huebner 2006). Schweitzer and Dey (2020) quantified those increases; after 3 years of annual fire, they documented a 34% increase of stems per acre from 12,600 to 16,900.
Most claims that fire is effective in controlling honeysuckle are anecdotal and lack scientific backing. It weighs on me when research is vague because it misguides our management resources. One paper I read referenced a claim that “as much as 50%” of honeysuckle was reduced with a single burn (Nyboer 1992). In digging further, the claim should have been that “35% of the ground cover” was reduced after 2 burns, and without additional follow up with herbicide one should expect regrowth (Barden and Matthews 1980).
Fact Sheets
Honeysuckle control fact sheets do not mention fire as a control method; an omission that cannot be ignored. This list is not exhaustive but rather provided as a sampling
- pdf (vtinvasives.org)
- pdf (in.gov)
- Shrub Honeysuckles (psu.edu)
- Wisconsin Extension has a cursory comment that fire shows promise but has no references to back this up. honeysuckle-pdf.pdf (wisc.edu)
- Wisconsin DNR does not advocate for fire Amur honeysuckle | (Lonicera maackii) | Wisconsin DNR
Conclusion
The last caveat is that fire or any other management techniques may produce different results in different ecosystems or in the same one at different times. We study research, we learn the plant’s biology, but we’re still at the mercy of nature!
Despite the labor-intensive nature of the cut-and-treat method, it remains the only known effective approach for eradicating honeysuckle. When planned time and resources are dedicated to follow-up treatments, control can be successfully achieved within 3 years. Beyond this period, ongoing monitoring and maintenance become essential, as birds will continue to “gift” us honeysuckle seeds, requiring continued vigilance.
References
Ashton, Isabel W., Laura A. Hyatt, Katherine M. Howe, Jessica Gurevitch, and Manuel T. Lerdau. 2005. Invasive species accelerate decomposition and litter nitrogen loss in a mixed deciduous forest. Ecological Applications 15(4): 1263-1272.
Barden, Lawrence S., and James F. Matthews. 1980. Change in abundance of honeysuckle (Lonicera japonica) and other ground flora after prescribed burning of a piedmont pine forest. Castanea: 257-260.
Charton, Katherine T. and Ellen I. Damschen. 2024. Grassland woody plant management rapidly changes woody vegetation persistence and abiotic habitat conditions but not herbaceous community composition. Journal of Applied Ecology: 1-13.
Frank GS, Saunders MR, Jenkins MA (2018b) Short-term vegetation responses to invasive shrub control techniques for Amur honeysuckle (Lonicera maackii [Rupr.] Herder). Forests 9(10):60
Guthrie, Shannon G., Raelene M. Crandall, and Tiffany M. Knight. 2016. Fire indirectly benefits fitness in two invasive species. Biological invasions 18: 1265-1273.
Hogan, Katherine F.E., Kaleb Baker, Elizabeth M. Bach, and Nicholas A. Barber. 2024. Basal bark herbicide treatment of Lonicera maackii (Amur honeysuckle) is effective regardless of application timing, with limited nontarget effects on native plant diversity. Ecological Solutions and Evidence, 5(2), e12332.
Huebner, Cynthia D. 2006. Fire and invasive exotic plant species in eastern oak communities: an assessment of current knowledge. Pages 218-232 in M.B. Dickinson (ed), Fire in eastern oak forests: delivering science to land managers. Proceedings of a conference. General Technical Report NRS-P-1. Newtown Square, PA: USDA Forest Service, Northern Research Station.
James, Jonathan J., Elizabeth M. Bach, Kaleb Baker, Nicholas A. Barber, Ryan Buck, Maryam Shahrtash, and Shawn P. Brown. 2022. Herbicide control of the invasive Amur honeysuckle (Lonicera maackii) does not alter soil microbial communities or activity. Ecological Solutions and Evidence 3(3): e12157.
Kline, Virginia M. and Tom McClintock. 1994. Effect of burning on a dry oak forest infested with woody exotics. Pages 207–213 in R. G. Wickett, P. D. Lewis, A. Woodliffe, and P. Pratt (eds), Proceedings of the Thirteenth North American Prairie Conference. Windsor, Ontario, Canada.
Knapp, Lauren S. Pile, David R. Coyle, Daniel C. Dey, Jacob S. Fraser, Todd Hutchinson, Michael A. Jenkins, Christel C. Kern, Benjamin O. Knapp, Dacoda Maddox, Cornelia Pinchot, and G. Geoff Wang. 2023. Invasive plant management in eastern North American Forests: a systematic review. Forest Ecology and Management: 1-28.
Krochmal, Gabriela Marie. 2024. Native Woody Diversity, Composition and Tree Growth Responses to Invasive Plant Treatment in Non-Industrial Private Forests. Purdue University Graduate School. Thesis.
Mandle, Lisa, Jennifer L. Bufford, Isabel B. Schmidt, and Curtis C. Daehler. 2011. Woody exotic plant invasions and fire: reciprocal impacts and consequences for native ecosystems. Biological Invasions 13: 1815-1827.
Medley, Kim A., & Mohrman, P. Travis. No date. Invasive bush honeysuckles: ecology, spread, and mitigation
Miller, Jesse ED, Ellen I. Damschen, Zak Ratajczak, and Mutlu Özdoğan. 2017. Holding the line: three decades of prescribed fires halt but do not reverse woody encroachment in grasslands. Landscape Ecology 32: 2297-2310.
Moser, W. K., Fan, Z., Hansen, M. H., Crosby, M. K., & Fan, S. X. 2016. Invasibility of three major non-native invasive shrubs and associated factors in Upper Midwest US forest lands. Forest Ecology and Management, 379, 195-205.
Nuzzo, Victoria. 1997. Element stewardship abstract for Lonicera japonica.” Nature Conservancy, Arlington, VA.
Nyboer, Randy. 1992. Vegetation management guideline: Japanese honeysuckle (Lonicera japonica Thunb.). Natural Areas Journal, 12(4), 217-218.
Rebbeck, Joanne. 2012 Fire management and woody invasive plants in oak ecosystems. In In: Dey, Daniel C.; Stambaugh, Michael C.; Clark, Stacy L.; Schweitzer, Callie J., eds. Proceedings of the 4th fire in eastern oak forests conference; 2011 May 17-19; Springfield, MO. Gen. Tech. Rep. NRS-P-102. Newtown Square, PA: US Department of Agriculture, Forest Service, Northern Research Station: 142-155., pp. 142-155.
Rich, R. 2000. Beautiful Species to Hate: Non-native Bush Honeysuckles: Invasive Lonicera species in the Midwest.
Richburg, Julie. 2005. Timing treatments to the phenology of root carbohydrate reserves to control woody invasive plants. University of Massachusetts Amherst.
Riley, S. A. 2013. Biology and control of Amur honeysuckle. University of Missouri-Columbia.
Rivera, Ben J. 2021. The Establishment, Control, and Post-Control Response of Amur Honeysuckle (Lonicera Maackii). Master’s thesis, Purdue University.
Schierenbeck, Kristina A. 2004. Japanese honeysuckle (Lonicera japonica) as an invasive species; history, ecology, and context. Critical reviews in plant sciences, 23(5), 391-400.
Schweitzer, Callie J., and Daniel C. Dey. 2020. Testing five treatments to control Lonicera and promote natural hardwood reproduction in north Alabama. In Proceedings of the 20th Biennial Southern Silvicultural Research Conference. USDA Forest Service, Southern Research Station, Asheville, NC, pp. 295-301.
Taylor, Quinn A. and Meghan G. Midgley. 2018. Prescription side effects: long-term, high-frequency controlled burning enhances nitrogen availability in an Illinois oak-dominated forest. Forest Ecology and Management 411: 82-89.
Ward JS, Williams SC, Worthley TE (2013) Comparing Effectiveness and Impacts of Japanese Barberry (Berberis thunbergii) Control Treatments and Herbivory on Plant Communities. Invasive Plant Science and Management 6(4):459–469.
Watling, James I., Caleb R. Hickman, and John L. Orrock. 2011. Invasive shrub alters native forest amphibian communities. Biological Conservation 144(11): 2597-2601.
Zouhar, Kristin, Jane Kapler Smith, and Steve Sutherland. 2008. Effects of fire on nonnative invasive plants and invasibility of wildland ecosystems.” In: Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L. Wildland fire in ecosystems: fire and nonnative invasive plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: US Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 7-32.