by The Prairie Enthusiasts | Oct 2, 2023 | Management Methods
Eliminating Buckthorn Without the Use of Herbicide
Story and Photos by Jon Rigden
October 2, 2023
Typical regrowth of buckthorn
Buckthorn is an invasive shrub that has infested many of the forests and bluff prairies of the Upper Midwest, including Hixon Forest in La Crosse where our Coulee Region Chapter has been working to control it. It is known that cutting buckthorn without treating the stump with an herbicide causes it to resprout. It is not known how frequently or how long buckthorn must be cut before it doesn’t resprout, or if it is even feasible to kill buckthorn by just repeatedly cutting it. Friends of the Blufflands has partnered with our chapter to help answer this question by sectioning off an area in Hixon Forest with heavy growth of relatively small buckthorn plants and cutting parts of that area at different frequencies. We hope to be able to determine the minimal frequency that young buckthorn needs to be cut to eliminate it without the use of herbicide.
Hypothesis
If young buckthorn is repeatedly cut it will eventually not resprout. The minimal frequency after mid-June until the first hard frost at which this cutting must take place is unknown.
Methods
A 400-square-foot study plot was chosen for its uniformity of buckthorn growth. The buckthorn was about waist to shoulder high with the diameter of stems mostly about half to three-quarter inch or smaller. This area was cut close to the ground on June 16 with a handheld brush cutter. The cut stems were gathered and removed from the area, then a second pass was made with the brush cutter to assure that all the stems were cut. The plot was marked off and divided into four sections, each measuring 10 by 10 feet. These sections go up the slope from bottom to top. The four sections were cut at four different frequencies (every 2 weeks, 4 weeks, 6 weeks, and 8 weeks). A border was also cut around this 400-square-foot plot. The nearby uncut buckthorn was used as a control. Subsequent cuttings were done from that date until the first hard frost, which occurred on October 25, 2022. It is recognized that new seedlings from the seed bank would appear and must be taken into consideration.
Cutting schedule (though the actual cutting took place near these dates due to weather or other factors)
10 x 10 feet sections marked off after cutting
On 6/16/2022 a 15 x 50 feet section on Lookout savanna, well east of an area that had been foliar sprayed the previous year and easily accessible from Savanna Trail in Hixon Forest, was chosen for its uniform growth of common buckthorn. The buckthorn was about waist to shoulder tall with the diameter of stems mostly about 0.5 to 0.75 inch or smaller. There were minimal other woody plants present, such as honeysuckle or oriental bittersweet. This area was cut with a weed wacker with a blade close to the ground, the cut stems were gathered and removed from the area, then a second pass was made with the weed wacker to assure that all the stems were cut. Then four side-by-side 10 x 10 feet areas were staked out within this 15 x 50 foot area. Down the slope and separated from the 15 x 50 area by a 3-4 foot cut buffer, a second 10 x 10 area had all the woody plants removed with the traditional cut and treat method using hand held pruners and 20% triclopyr in bark oil with surfactant and blue dye.
Study Plots Two Weeks Later on 6/30
The cuttings proceeded through the year according to the schedule with the last cutting of sections 1 and 3 taking place on 10/25/22 after which a hard frost occurred. Here are the measurements of growth in the 4 sections on this date:
Section 1
Top 5 averaged 1.5 inches of regrowh
Section 2
Top 5 averaged 2 inches of regrowth.
Section 3
Top 5 averaged 4 inches of regrowth.
Section 4
Top 5 averaged 5 inches of regrowth.
Status through the Winter
Photos taken on June 6, 2023
A view of the entire plot looking east
Note that some of the stakes fell over during the winter months. Also note that the green seen in the photos is mostly other plants such as violets, not buckthorn, except in section #4. As seen in the photos, sections 1, 2, and 3 were almost identical with some minimal regrowth of buckthorn. Section 4 had significantly more regrowth both in the number and height of the plants.
The separate section that had the buckthorn removed by traditional cut and treat was almost free of buckthorn on 6/6/23 with three plants still present. These were likely either missed or not enough of the herbicide was applied to be effective.
Conclusion:
Repeatedly cutting small diameter common buckthorn approximately every 4 to 6 weeks starting in mid-June until the first hard frost can be an effective strategy to eliminate most of the buckthorn and be left with very few stems and a much more easily managed population the next year. In this example that meant cutting the area 3 to 4 times from mid June to late October at 4 to 6 week intervals. Of note, the cuttings were done very close to the ground such that almost no leaves were left on any of the plants that had regrown. This might be difficult to replicate in a larger and rocky area.
This article appeared in the Fall 2023 edition of The Prairie Promoter, a publication of news, art and writing from The Prairie Enthusiasts community. Explore the full collection and learn how to submit your work .
If you’re interested in partaking in management research like this, send us a message!
by The Prairie Enthusiasts | Mar 31, 2023 | Management Methods
Controlling Clonal Tree Species By Double-Cutting
By Jim Rogala
Continuing on the theme of herbicide-free control methods, I’ll talk about my experience with double-cutting. Again we look to the anatomy and physiology of the species to be controlled to understand how this works [for those of you that know why double cutting works, or don’t care why it works, you can skip the next three paragraphs]. Clonal species form what looks like many plants when in fact it is a single plant with many stems. These clusters of stems often have larger older stems toward the center and smaller younger stems on the perimeter. No matter what the control method you use (mechanical or chemical), all stems of the clone need to be treated. Cutting off the stems in the winter results in the formation of new stems from adventitious nodes the next spring. Where there were tens (or hundreds) of stems prior to cutting, you might have hundreds (or thousands) after a winter cutting.
When to Cut
Cutting any plant when most of the energy stored in the roots has been translocated to above ground plant parts is advantageous. For most trees, this translocation occurs throughout the spring and early summer when it is building structures to 1) produce new energy, 2) to add to its size, and 3) for reproduction (leaves, trunk/branches, and flowers/fruit, respectively). After this annual use of energy from the roots is done, the tree begins translocating energy back to the roots at higher percentage. So, to deliver maximum hurt to the tree, cutting before energy starts going back to the roots is a good strategy. This maximum damage also minimizes prolific sprouting from adventitious nodes.
Even with a well-timed cutting, a tree still has enough energy in the roots to produce more above ground structure to assure it lives on. Here’s where the double-cutting comes in. After the first cutting, the tree needs to again use the remaining energy in the roots to build all new structures for the purpose of gaining energy (reproduction is put on hold under these stressful times). Similar to the first cutting, this second cutting is timed to coincide with maximum translocation of energy from the roots, but again not waiting past the period where a lot of energy is translocated to the roots.
I read about doubled-cutting years ago and have used it quite a bit. I generally follow the July 1 and August 1 timing for cutting but have varied it a little depending on growth in a given year (e.g., first cutting for sumac is usually after flowering). I’ve done the “cutting” with a variety of methods. I’ve used a mower if clones are large, where mowing is feasible, and the clone is not in a high-quality prairie. The point related to high quality prairie is that multiple years of repeated mowing can have negative effects on some desired species. I’ve found mowing to not be as effective, as it reduces shading of resprouts because everything gets cut. I’ve used a handheld brushcutter in native prairie areas, cutting each stem individually. It’s not as quick as mowing, but less damaging to other prairie species and better than using hand loppers to cut each stem. Loppers are effective for small clones. I’ve found that with sumac, you can actually snap off the stems in many cases (but be prepared to have the juices stain anything it gets on). Depending on the size of the stems, a Parsnip Predator can be used to cut the stems.
Where to Cut
Another variable to consider is the height of the cut. I’ve varied this as well, from ground level to 2-3 foot high. Cutting to ground level results in fleshy resprouts that can easily be second-cut with a Parsnip Predator. The really high cut was done to encourage resprouting only on the stem and to test if you get less new stems from the roots. This method allowed a second cut of a single stem, rather than the cluster of resprouts that come from the base. With this method, I found that the stem sprouts can sometimes just be snapped or stripped off, especially with sumac. The disadvantages are that some of the energy in the stem is retained, and the resprouts are not shaded by other vegetation. The method seemed to work as well as cutting lower on the stem in areas of sparser vegetation.
But Does it Work?
How effective is double-cutting on clonal species? I use it only on aspen and sumac; it’s been found to be ineffective on black locust. Because these two species are native, I’m not really all that concerned with eradication. However, I have eradicated many clones using double-cutting (with no herbicide), but most of those required several years of double-cutting. In one case, a single double-cutting killed a sumac clone. This was an older clone, so include that as one of the variables that might contribute to success when using double-cutting.
You might consider herbicides if you want more certainty in eradication. However, as Tom Brock pointed out in his management work (read here), even with herbicide it is a multi-year effort. For myself, I like the opportunity to control a native invading species without the use of chemicals. However, for the double-cutting to be effective, you must be timing the cuttings correctly, be cutting all of the stems in the clone, and continue the process as long as needed.
Read about other non-herbicide management techniques like using a Parsnip Predator, or girdling.
by The Prairie Enthusiasts | Mar 31, 2023 | Management Methods
Controlling Biennial
Invasives Without Herbicide
Using A Parsnip Predator
By Jim Rogala
My recent blog post on girdling got me thinking about other herbicide-free invasive species control methods. For biennials, there are three common mechanical control methods: mowing, pulling, and cutting below the root crown. Mowing is favored for large infestations because of the daunting task of methods used on individual plants. Pulling or root severing is feasible on small infestations. For some biennials, such as sweet clover, pulling works if conditions are right. However, there are some species where pulling is not that effective, and in those cases, root severing is a better method. In this post, I’ll discuss using root severing as a method to control biennials.
How it Works
As with girdling, the control of biennials also takes advantage of the plant’s anatomy and physiology to kill plants without using herbicides. In this case, we take advantage of the inability of many biennials to re-sprout if cut at some depth below ground level. These plants typically have taproots with all the adventitious buds (the source of re-sprouting) near the soil surface, thus allowing all the buds to be removed with below-ground cutting. Technically, many of these can live more than two years (they live until they flower), but without resprouts they are dead. Typically, cutting 2” or more below the root crown will suffice, but in some cases, I’ve found it successful at even less than 2”. There are many factors that affect resprouting, such as growth stage, nutrient storage, and other simultaneous stressors (e.g., shading), so keep these in mind as you decide how deep you need to go.
How to Cut the Crown
So, how does someone efficiently cut a root under the ground? The Parsnip Predator is a modified shovel that was designed specifically for this purpose by The Prairie Enthusiasts Prairie Bluff Chapter. Though obviously designed for wild parsnip, I’ve used it on other biennials such as sweet clover, burdock, and biennial thistles. I also find it handy to use on some annuals to minimize seed production, and for some perennials to set them back. I even use it for above ground severing of young tree sprouts when I’m double-cutting species such as aspen and sumac. I actually seldom use it as one would typically use a shovel, but rather just thrust the blade into the ground at an angle through the root of biennials or through the stems of perennials (and tree resprouts).
There are some advantages of root severing as opposed to other mechanical methods. As opposed to mowing, the severing allows the surrounding vegetation to stay intact, therefore not only leaving desirable species unharmed but providing shading of the potential resprouting biennial. Even though the repeated thrusting of the shovel is hard on the body, I find it less abusive than the constant bending over to pull biennials. And when it comes to parsnip, I like the idea of not having to grab a plant that has harmful juices in it! It can also be done under most soil moisture conditions, whereas pulling works best in moist soils.
The next time you need to address problems with biennials, consider using root severing to your potential management approaches and add a Parsnip Predator (or two!) to your toolshed.
Get Your Parsnip Predator Today!
Watch this video to see the Parsnip Predator in action!
by The Prairie Enthusiasts | Mar 30, 2023 | Management Methods
Jim Rogala
The intense transfer of materials within a tree at this time of the year makes for efficient girdling. Girdling is simply the removal of the “bark” to kill a tree. I use girdling as my go-to method for killing aspens clones. The method works best on clones where stems are at least an inch or two, although it can be used in combination with double cutting of the smaller stems (a topic for another post). It is critical to girdle all stems of a clone. I use it on a number of other species, including birch, but it doesn’t work on all species (e.g., box elder).
The key to successful girdling without using herbicide is to remove the outer layers (inner and outer bark) of the truck without injuring the innermost parts. I’ll bore you with the plant anatomy and physiology details in a later paragraph, but the details are really unneeded to accomplish the mission at this time of year. There is an obvious break between these layers when the tree is translocating a lot of materials upward, which is happening now. A person can simply run a tool between these layers around the entire circumference with a span of at least 6 inches wide. There’s no need to have clean cuts on the upper and lower ends of the separation, with the end-product often being somewhat banana-peeled looking.
There are a variety of tools that can be used to girdle, but from the description of the process above it’s obvious that a chainsaw is not one of them. For smaller trees, I often use a somewhat dull wide-bladed wood chisel. For larger trees, I use a flat pry-bar or a leaf spring cut to a manageable size and sharpened on one end. First I use the tool vertically to open an area to access the location between the layers, but this should be done without cutting too deeply into the tree. Then, put the tool between the layers horizontally and work it around the tree.
For those of you that are curious, here’s why this method works. There is a lot of specificity in the cells of a tree. There are those that transport materials upward in the inner layers (the xylem), and those that transport materials downward in the outer layer (phloem). Products stored in the roots, along with water, are sent upward. Products generated by photosynthesis in the leaves are sent downward. By removing the outer layer, the plant starves to death without the translocation of nutrients to the roots. You might be thinking that just cutting the tree might serve the same purpose. Well, that’s true for some species (such as cedars), but most trees have a strategy that includes resprouting from the base (or, like aspen, from rhizomes) when the xylem is disturbed. Be patient when looking for the results, as the tree will appear fine until the need for nutrients from the roots becomes great in the following spring. Sometimes it might take two years for the tree to die.
More information on girdling can be found by searching the web, but be careful to look for methods similar to what I’ve described here that don’t use herbicide. Tom Brock has a section on this topic on the Pleasant Valley Conservancy website (http://pleasantvalleyconservancy.org/brushandtrees.html). This method is not only effective, but minimizes the use of herbicides, which is attractive to me.
by The Prairie Enthusiasts | Oct 4, 2022 | Management Methods
If you have an old field that you would like to plant to prairie or a stand of oak you would like to restore, don’t rush into it. Understand the history of the land and take time to observe and learn whether anything important remains. Very often degraded lands still harbor irreplaceable elements of biodiversity, and these have their own stories to tell about what a place was and could be. The tools we use in restoration can encourage these elements or extinguish them. By recognizing and preserving remnant populations of native species and their genes, we can counteract biotic homogenization[i], and sometimes we can reduce project complexity and expense in the process.
Many landowners with prairie planting projects in old fields or retired pastures already have important elements of the biodiversity they are trying to restore, many of which are commercially unavailable. Occasionally remnant populations of rare plants persist. Even areas that were formerly cultivated often support good prairie, savanna, and oak woodland species that have recolonized from the edges, or perhaps a neighboring oak savanna that has since become forest. In many cases as many desirable native species remain as would be required for a seed mix planted under a cost-share program! I have included a table with upland species often encountered in old fields and pastures; there are many more. It is not uncommon to encounter five to fifteen of these species in an old field and ten to twenty of them in a retired pasture.
In cases where there are some good things present, start by managing these areas as though they were still prairie. Selectively control encroaching woody vegetation and any patches of broad-leaved herbaceous weeds. Burn for a couple consecutive years during the dormant season to encourage anything good that might be suppressed by the thatch. See what happens and go from there, which will usually mean integrating inter-seeding, a lot of burning, and patience.
Many landowners with wooded ground have land that was once oak woodland, oak savanna, or oak barrens. Oak woodlands are conservation-worthy and rare, but they are sometimes mistaken for forests or inappropriately treated as savannas[i] or barrens. It is far more common to encounter structurally intact ground layer vegetation in heretofore unrestored woodlands than open savannas. In oak woodlands, good cover of Pennsylvania sedge or dry-spiked sedge often remains, and species that tend to favor dappled light vs. deep shade or full sun—poke milkweed, pale vetchling, yellow pimpernel, broad-leaved panic-grass, bearded shorthusk, purple Joe-pye weed, Carolina vetch, etcetera—are often still present. Even where oak woodlands have become shadier, that change has usually been more gradual and less in degree than in savannas. This has allowed more of the woodland vegetation to hang on. Where a low sedgy or grassy ground layer remains, restoration might only involve modest brush work, removal non-oak understory hardwoods, non-oak overstory thinning/girdling, restoration of fire, and modest inter-seeding of missing species over time. Savanna restoration is critically important where true opportunities still exist, but good opportunities to restore oak woodland seem to be more common than savanna.
If you have an open area of cool-season grass or a stand of oak, I encourage you to take a closer look. You might discover there is more opportunity, or a different opportunity, than you initially thought. If you are looking for cost-share, go shopping for assistance that helps to build on what remains. Doing so should result in projects that conserve more community, species, and genetic diversity on the landscape.
Rich Henderson’s presentation “Converting Pasture to Prairie” on YouTube is an excellent resource.
______
i- Biotic homogenization is the process by which spatially separate ecological communities become more similar over time as the result of extinctions and invasions (or introductions).
ii- I use ‘savanna’ here in place of ‘oak opening’ for relatively open communities with mostly widely spaced, open-grown oak trees with prairie vegetation in-between.
______
| Species |
Common Name and Notes |
| Andropogon gerardii |
Big bluestem |
| Antenneria spp. |
Pussytoes |
| Aristida spp. |
Three-awn grasses |
| Asclepias amplexicaulis |
Clasping-leaf milkweed, sandy sites |
| Asclepias syriaca |
Common milkweed |
| Asclepias tuberosa |
Butterfly milkweed, sandy sites |
| Asclepias verticillata |
Whorled milkweed |
| Besseya bullii |
Kittentails, P |
| Bouteloua spp. |
Gramma grasses, P |
| Carex brevior |
Great Plains oval sedge |
| Carex gravida |
Heavy sedge |
| Carex normalis |
Greater straw sedge |
| Carex umbellata |
Parasol sedge |
| Cirsium discolor |
Prairie thistle |
| Crocanthemum spp. |
Frostweeds, sandy sites |
| Desmodium canadense |
Showy tick-trefoil |
| Desmodium illinoense |
Illinois tick-trefoil |
| Dichanthelium spp. |
Rosette panic-grasses |
| Erigeron pulchellus |
Robin’s plantain |
| Fragaria virginiana |
Virginia wild strawberry |
| Gentiana alba |
Cream gentian |
| Lathyrus venosus |
Veiny Pea, P |
| Lechea spp. |
Pinweeds, sandy sites |
| Lespedeza capitata |
Round-headed bushclover |
| Lithospermum caroliniense |
Hairy puccoon, sandy sites |
| Lobelia spicata |
Pale-spiked lobelia, P |
| Lysimachia lanceolata |
Lance-leaved loosestrife, sandy sites |
| Monarda fistulosa |
Bergamot |
| Oenothera perennis |
Small sundrops, P |
| Packera paupercula |
Balsam ragwort, P |
| Penstemon gracilis |
Lilac beardtongue, sandy sites |
| Primula meadia |
Midland shooting star, P |
| Pycnanthemum virginianum |
Mountain mint |
| Ranunculus fascicularis |
Early buttercup, P |
| Ratibida pinnata |
Yellow coneflower |
| Rudbeckia hirta |
Black-eyed Susan |
| Schizachyrium scoparium |
Little bluestem |
| Solidago juncea |
Early goldenrod |
| Solidago nemoralis |
Old field goldenrod |
| Solidago rigida |
Stiff goldenrod |
| Solidago speciosa |
Showy goldenrod |
| Sorghastrum nutans |
Indiangrass |
| Symphyotrichum oolentangiense |
Sky-blue aster, P |
| Tradescantia ohiensis |
Ohio spiderwort |
| Verbena stricta |
Hoary vervain |
| Viola sagittata |
Arrow-leaved violet |
‘P’ used for species more often found in pastures than old fields
[i] I use ‘savanna’ here in place of ‘oak opening’ for relatively open communities with mostly widely spaced, open-grown oak trees with prairie vegetation in-between.
by The Prairie Enthusiasts | Mar 26, 2021 | Management Methods
If you’re not familiar with the Parsnip Predator, you’re missing out!
Invented and produced by members of The Prairie Enthusiasts’ Prairie Bluff Chapter, the Parsnip Predator is a tool designed for prairie invaders like wild parsnip (Pastinaca sativa) and burdock (Arctium minus). It has gone through a few changes over the years, but it’s still just as useful for tackling taproots.
Now’s the time to “gear up” for another season of restoring healthy prairies. Visit our eStore and get your own Predator in time for the first wave of parsnip!
Thanks to The Prairie Enthusiasts volunteer Nick Faessler for the use of his workshop to create these useful tools, and for these photos showing the process.
Volunteer Gary Kleppe sharpens the notched blade of a Predator.
Once the Predators are branded, they’re ready to go!
