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Eco-Answers from the Pros: Managing Invasive Honeysuckle

I run an organic landscape design/build, and we constantly are dealing with honeysuckle removal. Currently our eradication method involves cutting the honeysuckle down to the stump and applying an organic herbicide like Burnout or Avenger. On a small scale, we will also cover the stump with heavy duty landscape fabric. On a larger scale, we expect that there will be some grow back and will be back another time to cut back any regrowth. Are there other organic approaches to honeysuckle eradication?

When I visit a project site for the first time, I have usually seen it from above via online mapping, so the actual walkabout serves to confirm the landowner’s observations, reveals safety hazards, and gives me an opportunity to study the terrain limitations. Usually, but not always, the landowner is prepared to have me on site a couple times annually for several years, so we’ll discuss the seed bank and any immediate land-use plans that may be disruptive. I take note of the maturity/size of the target species, the competition in place, and the potential for erosion. The schedule is important as well; any work before mid-July is fairly certain to break viable seed formation, while later work efforts will need to carefully address formed fruit and potential dispersal.

Knowing that I’ll be present on a dynamic site multiple times, I act with an eye toward future safety, access, and efficiency. Oriental bittersweet is common on infestation sites, and if it has weakened nearby trees, that issue gets addressed to remove any overhead hazards. Then I note locations for brush piling and scattering of small branches and debris. Once a picture comes together in my head, control work focuses first on the most mature shrubs that are producing seed. I may leave SOME vegetation on south-facing edges, just to buy one more growing season of shade, but in general the fast-maturing shrubs (glossy buckthorn) and the oldest, heavy-fruiters get priority treatment.

My methods include pulling/uprooting if the site can handle soil disturbance, flaming the root collars in the fall months, and stump-cutting or girdling the larger specimens. Size dictates the approach used for pulling; smaller shrubs are hand-pulled, while tools are effective up to base diameters of three inches. I do often girdle larger shrubs like twenty-foot buckthorns in the spring, but once they have a crown full of fruit, it’s wiser to bring them down and consolidate all that seed into piles. Burning is not necessary; it’s simply best to have all the fruit down on the ground in singular locations that can be dealt with later. Compact, well-constructed piles not only reduce spreading by birds, but also offer cover for ground nesting species and future decomposed organic matter, a soil positive.

Stump-cutting leaves behind a skeleton or bare frame of the shrub. Multi-flora rose, autumn olive, burning bush, European barberry, the buckthorns, and honeysuckle can all be lopped back to the largest stems. When re-sprouting occurs, this material gets stripped off either by hand or with snips. Ideally the target species get stressed by treatment three times over two growing seasons. When germination creates a burst of new growth from the seed bank, those small shrubs are vulnerable to hand-pulling, judicious scything, and even controlled burns (more common in the Midwest) or grazing. I rarely deploy the brush-saw, but there are times when it is the best fit. Stone walls are tricky; ANY disruptive methods can potentially unsettle the stones, so repeat passes with the brush saw may be ideal if one does not mind constantly sharpening blades.

It is often the third growing season when change becomes truly apparent; mortality of the fruit-bearing shrubs is essentially complete and full attention on the soil seed bank will stymie follow-on waves, even as existing native shrubs begin responding to the new light conditions and nutrient availability. Indeed, it is the “sunlight management” piece that plays the most important role. Whatever spaces have been opened up with treatment work need to be filled in quickly; if native regeneration proceeds too slowly, it is helpful to bring that along with transplanting or installation of desirable species.

~Mike Bald, Got Weeds? Vermont

 

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