To do it right, don't overlook all these key points: 0:00 background 1:15 how girdling works 2:10 technique: initial cut 3:10 technique: peeling 4:15 technique: cleanup with blade 5:55 technique: cleanup with abrasive pad 6:45 technique: cleanup with alcohol 8:10 treating the whole tree
Good Job, Cliff! Very thorough. I usually use a saw to make the initial cuts and a 5-way tool to peel the bark. A really sharp 5-way tool. Don't usually spray after if I take the time to insure all the cambium is gone. This is not as easy as it looks, people!
I guess I can’t post pictures here, but I checked these trees out March 4, 2020-about 7.5 months after I had girdled them-and no tissue had grown in the gaps and no sprouts had formed below the girdle. (After the video was done, I stayed and finished girdling all 7 of the other trunks on this tree, two of which were hidden behind the others.)
I think this comment got cut from the video, but it's important: When you're peeling the bark and phloem away from the trunk, you won't see the difference in color that shows up in the video. On camera, the beige shade of the exposed sapwood and the bright white of the phloem are easy to distinguish. With the naked eye, both seem to be ivory-colored. It's easy to miss seeing that you left a lot of phloem behind. On the other hand, if you leave the girdled trunk alone for a few minutes, both the phloem and the cambium on the surface of the sapwood will darken. Better yet, they will darken to different shades of brown. Then it's easy to see what's left and to know when you've finished removing it. So when I girdle a multitrunked tree, I will do all the work with each tool before going to the next tool: 1. Circumferential cuts with the carpet knife-on every trunk. 2. Peel away the bark and phloem with the putty scraper-on every trunk. 3. Now that the trunks are darkening, start with the first trunk I peeled and do a quick follow-up scraping to remove the big pieces of phloem-on every trunk. 4. Starting again with that first trunk, scrub with soapy water and a coarse scrubbing pad-on every trunk. 5. Again, starting with that first trunk, scrub with rubbing alcohol (70 percent isopropyl alcohol; check the label) and a finer scrubbing pad. If a tree has only one trunk, I will girdle several other trunks at the same time, working through the same sequence. By giving each trunk a few minutes to age between steps, I make it easier for me to see the tissue I need to remove.
You might find other videos on girdling, but I can save you some time. Once way or another, I have tried all those techniques, and they haven't given the success we've had with this technique. On one area we followed rigorously so we could report the results to a sponsoring agency, we had a 99.7 percent kill rate at 2 years after completion of the year-long project. That's close to 300 trees, and only one still alive 2 to 3 years after we girdled it. I did in the meantime monitor the results every 3 to 6 months and fix the few trees on which the technique had not been perfectly executed at first. I have seen only one large-scale study that documents a success rate even approaching this. In that study, the researchers used basically the same technique. (They did not scrub the sapwood clean. Instead, they vigorously scraped all the phloem and cambium away. I've done that. It does work, but it's a lot more difficult and significantly less successful-perhaps 90 to 95 percent instead of better than 99.7 percent-or requires significantly more followup work to get a comparable rate of success.) I have seen many studies of the impact of girdling on trees in which the overall success rate was no better than 50 percent. Generally the point of those studies was to see how different species respond to girdling, or how trees of the same species in different settings respond to girdling, or how an aspect of tree growth was affected by girdling.
Thanks for this video. It was very helpful. I started experimenting with girdling black locusts a couple of years ago on my property. I girdled them in the fall. I didn't realize that the girdling should be done when the trees are leafing out to put additional stress on the root system. That seems really important. I got robust sprouting from my girdled trees below the girdle.
II developed this method so Adopt-a-Creek volunteers could tackle this and other invasive trees on the segments they care for. Without proper licensing, liability insurance, and a signed contract, the city won't allow us to use herbicides. Of course, then we would be contractors, which takes all the fun out of it. (Power tools are also forbidden.) We do have a city employee who is licensed to use herbicides, but our many volunteers can make far more progress than he ever could. We can use a wide variety of people-8-year-olds to do the scrubbing; Scouts with their Whittlin' Chip to make the cuts (although we actually restrict that to 18-year-olds unless a responsible adult who brought the youth is supervising closely); office employees looking for a different way to spend a day volunteering in the park; fraternital organizations; so many others. We've noticed another advantage over areas where a thick infestation is controlled with herbicide. The herbicide kills the treetop so quickly that native plants that have been struggling in the deep shade beneath the privets often burn up in our hot Texas sun. But a girdled tree shows no symptoms for weeks or months, then shows drought stress (wilting over the course of the day, then rejuvenating at night), and eventually starts dropping leaves. It's hard to assess how much light reaches the ground by the time the root system dies, but in a study in which about 40 trees died, there tended to be only 30 to 70 percent open sky when looking up from the base. So the tree was still casting mottled shade at the time the root system died. Under those conditions, many saplings and plants have responded well to the slowly increasing levels of light. The oversized, soft leaves of a tree struggling in deep shade were replaced with increasingly (?) smaller, more leathery leaves characteristic of a species adapted to direct sun. We generally don't have to replant, unless we want to adjust the habitat. In many of the areas where herbicide was used, the city struggled to reestablish a native landscape in what had become a barren space. Again, barren not because of herbicidal drift, but because of a change from deep shade to full sun over a few days to a week. That's a benefit we weren't expecting. (In the few places where we don't see many woody species or understory plants reestablishing themselves, I suspect the area was a meadow before the privets moved in.)
I was going to ask the same question, but what a great response Cliff. I mean, it's very labor intensive, but does seem to do a great job where one must abide by rules and such. I'm taking on a huge invasive project on my 160 acres in Kansas. We could never work this slowly. I'm hoping for the best. Im working with our state forester and local NRCS office for a true Cross Timbers restoration.
It’s especially important to be thorough when you can’t get back to the trees easily. But if you can get to the trees easily, then you might be able to be less thorough on the initial job and follow up later on only those trees that show signs of recovering. Especially when hot, dry weather follows your girdling project this might save time. Last weekend my cutters and peelers got way ahead of my scrubbers, so I have 50 trees (202 trunks) done and more than 100 trees (and probably at least 300 trunks) that have had a collar removed but have mot been scrubbed. Because they’re all within sight of a trail I hike at least once a week, I can keep an eye on the progress of those incomplete trees and follow up as needed. We’ve had dry weather, so maybe I’ll be lucky and much of the residual cambium will dry up and die on its own. But often it's such a pain to even get to the trees that I want to be sure to get it right the first time.
@@clifftyllick8529 Question for you: I imagine this is not part of your process at BCP, for multiple reasons, but at what point after girdling would it be okay to cut down the tree if desired? I think my first attempt at girdling a mid-sized chinese privet in our NTX yard is succeeding thanks to watching your video. Girdled it last May and now all of the leaves have dried up and started to fall (including on a couple small sprouts below the girdle line, which seems promising). Going to plant some native shrubs nearby and would like to cut it down, but only once it's done exhausting the roots to avoid new sprouting.
Of course that works on young, thin-barked trees. And to young trees maintenance crews are more lethal than rodents. If the string trimmer weren't a power tool, we could use that approach. But our volunteers can't use power tools. (That's a bonus: without power tools, misguided volunteers can't wreak nearly as much havoc as your maintenance crews do.) Besides, the trees we work on have an average of 3 trunks each. Many are single-trunked, but the multiple-trunked trees usually have at least four trunks and often have more than a dozen. There is a lot of phloem included between the trunks at the base, so the line trimmer would be completely ineffective there. Where the trunks do eventually separate-usually waist high, sometimes over my head-it's hard enough to slip a cutting tool between them. You'd have no chance with a line trimmer. Your (no doubt facetious) suggestion illustrates how wrongheaded it is to use a chainsaw or any other tool that cuts deeply into the sapwood,. A monofilament line just a millimeter or two thick can only remove the bark, phloem, and cambium from the base of a young tree. It couldn't even bruise the sapwood of most woody plants. Normally you would have to remove a band wider than 2 centimeters to ensure that the gap doesn't heal over before the tree dies, but in your case the maintenance crew returns regularly and reestablishes that gap, so if it bridges at all it doesn't remain bridged for long. Eventually, the root system will starve to death and the tree will die. All you (or, in this case, our wonderful landscape crews) have done is to remove that one layer that carries the sugar. No need to rip into the actual wood. The sapwood isn't where the work needs to be done.
In many settings, either herbicides are not allowed or, as in my case, volunteers are not allowed to apply them. With hundreds of acres to cover, the biggest drag on progress is the time required to monitor success and remediate failures. We've had a significantly greater rate of success with this method than contractors using herbicide have had in their work. Your mileage may vary.
Cliff, I'd like to harvest the canopy for my goats to eat. In the video you explained that the leaves need to remain to put a stress on the tree of trying to pull sugars up out of the ground to thoroughly kill the tree. Is there a midway point here? Can I leave a branch to still create the demand in sugars while taking the rest for my goats?
Hi, Jenny! The short answer is no, you can’t let your goats eat any significant amount of the canopy. Let me correct a misconception, too: The canopy gets water, not sugar, from the root system. The root system starves because we’ve removed the tissue that resupplies it with sugar made in the canopy. For this to work, we can’t give the tree a chance to grow new shoots from below the girdle. So long as the canopy above the girdle demands every drop of water the root system can produce, the base of the tree won’t be able to grow new shoots. It will try, but the shoots won’t thrive because the treetop is using all the water. If we reduce the canopy, the tree will be able to support the growth of shoots from below the girdle. Instead of staying thin and green, the shoots it forms will thicken, cover themselves with bark, and keep growing. With the sugar produced in their leaves, the root system no longer starves. The tree survives. Thinking this through, though, maybe you shouldn’t girdle the trees. Cut them at the ground, feed the canopy to the goats now, and then let the goats graze on the new sprouts from the live trunks. The goats will keep the privets from ever getting big enough to flower and might eventually kill each of them outright. See, usually the problem with cutting privets to the ground is that we can’t stay ahead of the new shoots sent up from the stump. If we could strip off every one of them as soon as it formed, we could kill the tree in a year or two. Most of us could never do that. You, on the other hand, have an army of goats to do that work for you. See if it works!
Jenny, in my first answer, I forgot a very important aspect of this: Where we have thick infestations of glossy privet, we also have many younger trees, small enough we can uproot them, but still over 10 feet tall. That's a lot of browse for a goat! So the girdled plants can't provide the browse, but I have plenty of places where we would need to dispose of a trailer load or so of uprooted smaller trees. In fact, we sometimes have to uproot a thicket of small trees to reach the tree we have to girdle. Do you happen to be near Austin?
Could one use a cordless angle grinder with a sanding disk to remove the cambium? Thanks for showing a safer way to get rid of the trees without the potential for harming my oaks.
Grinders and sanding disks are designed to work well on dry wood. The live tissue will gum up the disk or grinder. When I was experimenting with ways to make girdling always work, I first tried sanding pads and wood rasps. They gummed up before I had cleaned even a 4-inch-diameter trunk. Another problem with rasping tools-and with power tools in general-is that you can’t tell when you’ve finished removing phloem and cambium and are starting to grind into the sapwood. If you remove too much sapwood, the basal sprouts always produced by girdled trees will thrive. Those thriving shoots will keep the root system alive, which will make the girdling fail to kill the tree. The grinding surface will also embed bits of phloem and cambium deep into the sapwood. That embedded tissue will find plenty of water in the sapwood to keep it alive, and it will more often than not grow into new cambium, phloem, and bark to bridge the gap. Again, the girdling will fail. People always want to use power tools in the woods. They're loud, heavier, and more cumbersome, and they don't work nearly as well. A friend of mine who is a plastic surgeon told me that this technique is a lot like his work. He has to lift layers of tissue and separate them, intact, from the adjacent layers. In both cases, the best results are produced by probing between the layers with a dull tool and then lifting the layer that is to be removed. It might help to keep that in mind. We aren’t butchering a carcass into pork chops. We aren’t sandblasting old paint and rust off a metal post. We aren’t cutting tile or polishing stone. We’re doing surgery, or at least a dissection. We’re lifting a layer of tissue from a living organism. For greatest success, we need to keep that layer intact as we work, and we need to leave the layers beneath it as close to unscathed as we can manage. Power tools won’t do that.
@clifftyllick8529 This is great too because especially for commercial jobs, the balcones canyonland preserve in this area has the golden cheek warbler (bird) protections up which wont allow you to use power tools during the coolest months of the year. (ideal sawing times) -or if you're close to an HOA that has bans on noise. -It's one more tool in the toolbox to solve problems with low tech tools that are readily available to everyone.
Hi, Beaux! It depends. Scratching into the xylem has almost no adverse effect. Cutting a quarter-inch into the sapwood of a 12-inch trunk will also have almost no adverse effect. But cutting an extra quarter-inch into a 1-inch trunk will let the base of the tree live while the top dies. In the long run, it would be as if you cut the tree off at that level instead of girdling it. By now, you should be able to tell whether your cut went too deep: • If it did, the sprouts that (almost) always form from the trunk below the girdle will have put on bark, grown to more than a few millimeters wide, and continued to grow in length and girth. (Those sprouts are called basal sprouts.) • If it wasn't deep enough to cause problems, those basal sprouts will still be no more than a few millimeters wide, probably will have no hardened bark on them at all, and instead of continuing to get longer and thicker might actually be withering at the tips. They might be four or five feet long, but they won't be thickening at the base and probably won't get much longer than that. If the basal sprouts are hardening and growing thicker, the problem could also be that you left tissue bridging the girdle (or, if you had to girdle more than one trunk on the same tree, any one of the girdles). So if you see that, the first thing to do is to look for bridging tissue and, if you find any, remove it. Don't just scrape the exposed bark off of the new tissue, because there is almost always some new phloem between that bridging tissue and the original sapwood. You have to remove that inner phloem, too. After you have removed the new tissue, girdle all sprouts that are at least a centimeter or so in diameter and strip away all of the weaker ones. If you don't see any bridging tissue, then the problem is probably that you did cut too deeply. crazy as it might seem, you now need to let at least some of those woody sprouts continue to grow. Strip off all but a few that are spaced widely enough that it will be easy to girdle them. Let them grow until some time next summer, and then girdle them. (You can do something right now to make sure it's easy to girdle between each of those new shoots and the original trunk: jam anything between the shoot and the original trunk to create a gap between them.) Here's more about what's going on. Botanists describe trees as "ring-porous plants." That makes sense when you think of the cross-section of the tree-the sapwood is a series of lighter, more porous rings separated by darker, less porous rings. Water wicks through those rings from the roots to the treetop. The outermost layers carry the most water, and the innermost layers might carry none at all. The problem with cutting into the xylem arises when you go deep enough to significantly reduce the flow of water past the girdle to the top of the tree. That's why scraping a little sapwood off rarely matters, and that's why I can't give you a precise answer as to how deep would be too deep. As I suggested above, the only way to know if you've cut too deeply is to observe the tree and see if the base starts recovering. A proper girdle will kill the base before the treetop dies. If the base looks better than the treetop, something is wrong. A few points more: • I know from experience that cutting too deep can be a problem. I have seen trees that were dead from the girdle up and still alive-and thriving-at the base. On those trees, at least one of the circumferential cuts went much deeper than necessary into the sapwood. • I would like to explore your question in my next experiment: How much is too much? What difference does it make in the fate of a 2-inch tree if you just scratch the surface? If you cut 1/4 inch into the xylem? 1/2 inch? What about a 4-inch tree? Or a 10-inch tree? • Above, I told what to do when you see the basal sprouts thriving. Other than those cases, I never strip any basal sprouts from below the girdle. They are like signal flags I can see from ten or twenty yards away-if they're wimpy, everything is fine. If they're getting vigorous, I need to get over there and see what's wrong. So long as they stay wimpy, they will die on their own when the base of the tree is dead. I shouldn't waste time removing them. • I implied above that when a girdled tree thrives there are more than these two possibilities-a bridged girdle and a cut made too deeply. There is a third: the tree is interconnected to another glossy privet through its root system. I have not seen evidence that separate privets will connect their root systems, but I have seen instances in which the exposed root of a large privet produces a sucker, sometimes 5 or 10 feet away, and that sucker grows to the size of a tree. I've also seen cases along streams in which a ligustrum got toppled by a flood and buried in sediment, and then each of its exposed branches grew into a trunk. In those cases, just as with a tree that has 5 or 6 trunks growing from the same base, you have to girdle every trunk on the same root system before the tree will die. For me, this has been very rare, but in some other setting it might be more common. Beaux, thanks for asking!
Hey, I see you're operating a fruit farm. As you know, you can girdle an individual branch on a tree to make the fruit on that branch grow larger and sweeter. That technique also fails if any connection across the girdle remains. The same technique I described here would ensure that the girdle is done properly in that setting, too.
Sorry I didn’t see this earlier. On a fruit tree (avocados are fruits), you could do this on an individual limb to get sweeter, larger fruit on that limb. Don’t do it to the trunk because you would then kill the whole tree. For an added effect, strip half to two-thirds of the fruit from the girdled branches.
If by air layering you mean packing the soil or other growth medium around the girdled section, I think it could work. Because girdling prevents sugars produced in the branch from being returned to the root system, there would be more sugar available to grow roots in that medium. Just be sure to pack it around the upped portion of the gap and a half inch or so of the bark above the gap. In this case I don't think you would need to scrub the gap clean. Even if there is a trace of tissue bridging the gap, there will still be a lot of sugar that can't get through, and that sugar would be available to support vigorous root growth. At the same time, because you haven't damaged the sapwood the branch would be receiving every bit as much water as before. Girdling could also improve results with layering by bending a branch down and burying a node or two In this case, you would girdle between the node or nodes you bury and the rest of the plant. Again, the branch would continue to receive as much water as before, and the sugar that can no ;longer travel to the roots would be available to support the growth of the new roots from the buried nodes. Thanks for asking! You've given me a couple of ideas for propagating native plants not easily found in commercial nurseries.
@clifftyllick8529 wow now that's a loaded explanation 👏. Thanks a bunch! Do you have a RUclips channel that I can enjoy & learn from more content like this?
Great video and info. I'm wondering if this would be a good time to start girdling more of them, given the stress they've had with the last month's freeze. Or would it be better to wait a few month until they've pumped their carbohydrates to grow new leaves and then girdle them to burden them at that point? \ Have you ever tried spraying with salt water, and could that work? Rubbing alcohol right now is precious right now for our household during COVID, so am looking for short-term alternatives.
Great questions. From Cliff: By all means, girdle now! So long as you have all the necessary permissions, the best time to girdle a privet is whenever you're standing next to it with the tools at hand. As said in the video, scrubbing with soapy water is enough by itself if you clean the gap thoroughly. You could use any gentle cleaning agent, either alone or as a second scrub. The most important thing is to check your work again before you leave. The xylem will stay light colored. If you see anything turning darker brown, scrape or scrub it away.
I do not, and am very interested to find out. Fortunately there is a dearth of TOH (Ailanthus altissima) in my immediate area. My guess is that it might work on trees that have not yet produced root suckers. On two Callery pears that had recently produced suckers-that is, the suckers were no more than 3 feet tall-both the main trunk and the suckers died, even though the suckers had not been girdled. (Until they died at the same time as the main trunk, I hadn't realized that the adjacent sprouts were suckers.)
Thanks for your question, Yasmine. This technique is used to control the invasive tree, Glossy Privet. Glossy Privet (aka Ligustrum) is an invasive species that will spread to take over an area and shade out and kill other beneficial vegetation. Because it is destructive to local ecosystems, we work to control this species on the Balcones Canyonlands Preserve by girdling large Glossy Privet and pulling out seedlings. Girdling allows native seedlings to establish and replace the Glossy Privet canopy as these non-native, invasive trees slowly decompose. Before girdling a tree, it is very important that a person correctly identifies a tree as Glossy Privet, so as not to a harm non-invasive trees. To learn more about how to identify Glossy Privet and other invasive plants, visit: www.austintexas.gov/sites/default/files/files/Watershed/invasive/2013_Invasives_guide_small.pdf. We love native trees and plant many new trees on the preserve every fall and winter. To learn more about the many benefits of trees and how to plant a tree, check out our other videos in our Forest Restoration webinar series: ruclips.net/p/PLUg_t5WZwkb9qp7xVtgbtD2JMqS8D8ko5
@@yasmineset7045 great question. Thank you for asking! Girdling also has other purposes. In some countries, girdling is traditionally used to create standing deadwood for heating or cooking fires. Wood in the air is easy to reach, stays drier, and is less likely to rot before you gather it. On tree farms, I understand that some otherwise desirable trees are girdled to thin the crop and let other trees grow as desired. I don't know how frequently tree farms would do that. As I mentioned in another reply above, girdling is also exploited in fruit orchards. In that case, they girdle one or no more than a few branches on a tree to block the transport elsewhere of sugars produced by that branch. That results in larger, sweeter fruit on that one branch, because the sugars (and related metabolic substances) can't be used any other way. I don't know if that method results in the death of the branch. Because other branches keep feeding the root system, the girdled branch might well continue to survive. I'd have to ask a fruit farmer.
"grim reaper of ligustrum" 😂 -that's my line! -or I guess that make me the "Prince of Privet-Destruction" or the "Annihilator of Arundo Donax" 😂 -Fight the good fight ya'll! "-The Justiciar of Johnson Grass has weighed and measured your monoculture and found it wanting..." B\
Three factors reduce that likelihood. One is general, and the other two are particular to glossy privet. I'll start with those that apply to glossy privet. 1. In our setting, because the glossy privets are either growing through the canopies of deciduous trees or densely packed among themselves, they can't fall. When we have cut the dead trees, we have had to pull them out of the canopies. A few have been so intricately interlaced in the deciduous canopy that we couldn't drag them out. 2. By the time a glossy privet is rotten enough to fall on its own, the top is so dry that it is too light to do much damage and so brittle that the impact would be absorbed by the breaking of the small upper branches. (Glossy privets don't have a lot of mass up high anyway.) 3. Girdling works by making the canopy a parasite on the root system. It uses all the water the root system can produce and provides no sugar in return. The canopy remains alive-somewhat thinned, but still alive-until shortly after the root system dies. You'll know when the root system dies because the basal sprouts will die with it. At that point, the tree is still sturdy. Because the root system is dead, you can cut the tree down without triggering new sprouts.
On glossy privet, the axe will cut too deeply, and you’ll get vigorous regrowth from below the girdle. In other words, the tree will survive. This method is extremely effective for eradicating infestations of invasive woody plants. It does depend on your goal: Reduce the number of trees of a certain size or species? Or kill absolutely every tree with the goal of eradicating its species? Kill just the aboveground portions of the tree? Or kill the entire root system, so there are no resprouts from the base and no new suckers after the top dies? It also depends on how frequently you can return to the area to check results. We have so many acres to cover that I can’t waste time checking up on our past work. I typically check the quality of work within a week and then check the progress once, 6 months to a year later. Every tree we girdle dies. And the root system dies first, so there’s no way the trees can regrow.
The video explains why and how girdling works. Chainsaws are useful for cutting off large branches and cutting down large trees. Cutting down a tree doesn't necessarily kill it. Doesn't kill camphor trees, redwoods, melaleucas, eucalyptus, Brazilian peppers, and many other species.
Interesting. I've killed many a tree by simply digging down to a large a root then drilling a 2" bore hole in it and pouring in the resulting root "cup" 4 ounces of 41% glyphosate (Roundup). This will take out any tree under 24" in diameter. It takes about 2 months. For larger trees, treat more than one root. T-i-m-b-e-r!!!!! - You can also find an apron feeder root and insert the small root fingers in a glyphosate water bottle. Soon the root will empty the bottle (Thinking that the liquid death is water).This also works well; but not as fast.
Our volunteers cannot use herbicides, so your technique won't work under our conditions. We can put dozens of willing and eager volunteers into the field and make steady progress in large areas. In fact, the city asked us to make this video because we were outpacing the licensed employees who were applying herbicide, and we actually get a better kill rate. So their employee can do other tasks, which is a big boost given their severely understaffing issues. If you prefer to use herbicides, you should instead use the better, more efficient approach called frilling or sometimes something like clip-and-drip. You make cuts into the phloem, not the sapwood, in alternating locations around the trunk and trickle or daud the concentrated herbicide onto the phloem. With a proper application of the herbicide, there is no dripping or overspray. Your 4 ounces of concentrated herbicide could do a dozen trunks or more, not just one. An agency in Pennsylvania describes that technique clearly for killing tree-of-heaven. If you search for their flier you'll find a way to save time, material, and money. (For one thing, there is absolutely no reason you need to dig down to find a root. You work on the trunk at whatever height is accessible to you and comfortable for you.) To have an effect on the plant, herbicide applied to sapwood must first travel to the phloem. The thicker the trunk or root and the farther you go into the sapwood, the less of your herbicide makes it to the layer where it does its work. Again, applying the herbicide properly, you can treat more invasive plants with less work and far less chemical.
I developed this technique by studying why that very approach did not work. When used by half a dozen volunteer groups that I knew of and, in the same program, by quite a few more, cutting into the sapwood produced 100 percent failure. There were four reasons for this. First, even when they cut into the sapwood, they also left strips of phloem connecting or nearly connecting tissue above the girdle to tissue below the girdle. Those trees quickly recovered. Second, if they cut too deeply into the sapwood, the flow of water to the treetop was restricted at the girdle. The base of the tree produced sprouts that thrived. The top of the tree died quickly-sometimes within a few weeks. The root system remained alive. Instead of having a dead tree a year later, we had a thriving tree with 5 to 15 times as many trunks. This often happened on trees on which each trunk was no more than about 3 inches in diameter. Third, on larger trees, the layer of phloem is thick enough and woody enough that people think they're cutting into sapwood when they haven't even gotten through the phloem. "I know I got it right, because I cut into white wood," one volunteer told me. Those trees form new bark within weeks. If you look closely, you can see a difference in the surface of the bark where the girdle was, but the tree was not noticeably set back. Finally, even when we meticulously got between the phloem and the sapwood with the scraper and peeled a full 4- to 6-inch-wide collar of phloem away, bits of phloem sometimes remained behind and a film of cambium always remained behind. If the weather was not hot and dry, that residual tissue was usually able to grow a new bridge of phloem and bark across the gap before the tree died. Scrubbing the phloem and cambium away without cutting into the sapwood turns out to be the key to a reproducibly high kill rate. I tried many variations-making sure to cut deeply into the sapwood; scraping the residual tissue away (effective if done meticulously, but slower than scrubbing, and requires such vigorous effort that I needed to ice down my hands, wrists, elbows, and shoulders after each workday); removing a narrower band of tissue (actually more work, because it gives us less leeway in working the scraper under the bark); removing a wider band of tissue without scrubbing (one group removed strips 2 feet wide on several dozen trees-with 0 percent success); and more. Each of those variations either failed or was far more difficult. This works. Also, when we do this with a group, we can speed the process up by having one group start early and do the two cuts, another group come behind and do the peeling, a third group scrub with soapy water, and a fourth group scrub with alcohol. This lets us add volunteers who can't be trusted with sharp tools. For example, folks have brought their 8- to 12-year-old kids to do the scrubbing. They do a great job. With more sets of eyes examining the quality of the job, we have fewer failures for me to find and fix in the next few months. The volunteers really enjoy it!
You're right about the chemicals. Even water is a chemical. But our volunteers are not allowed to use herbicide, so we use common household chemicals that are essentially inert. Soapy water and rubbing alcohol release different kinds of gluelike substances in the bark and make the peeling somewhat easier. Working with various groups of 12 to 40 volunteers 5 to 10 times a year, we killed 99 percent of the mature glossy privets on about 30 acres and uprooted the next generation on 10 of those acres in 2 to 3 years leading up to the pandemic. Once we get to the entire park, we will have plenty of time to uproot or girdle that last generation before a single one of its privets reaches maturity. Because teenagers can do the cutting and peeling and kids as young as 8 can do the scrubbing, we have been able to lead high-school science or service clubs, Rotarians, youth sports teams, families, Scouts, companies wanting something unusual for team-building events, groups on leadership development retreats, fraternal organizations working as part of a reunion, science clubs, and more. Insanely labor intensive? Maybe, but our volunteers come back eagerly. Please don't tell them! If you have the training, certification, and equipment required to use other methods and cannot get access to volunteers, go for it. But we're getting great results under the conditions possible for us, so we'll stick to this approach. It's essentially free, it's highly effective, and it builds a sense of ownership of and appreciation for our green spaces among the people who use them.
We've had one large group remove 12 inches of bark without following this method and another remove 24 inches. Both had failure rates of 100 percent. If you damage the sapwood too deeply, the top dies before the root system and the trunk produced many new sprouts. A year later, you have a multitrunked tree to deal with. If you don't scrub the residual phloem and cambium from a band at least 2 inches wide, the trunk will cover itself with bark again in a matter of weeks. I had one volunteer who peeled all the bark and phloem off three large trees-a total of 10 or 12 trunks-from chest-high (not quite 5 feet up) all the way down to the ground level. Each looked like nothing but bare sapwood was left. A week later, the entire length of each trunk was covered with regenerating tissue. Trees left like that develop new bark over the whole area in a matter of weeks. Of course, they survive. I scrubbed a band 2 to 4 inches wide around each of those trunks. The rest of the areas finished covering themselves with bark. As is usually the case, little if any new tissue grew into the girdle from below and just over 5/8 of an inch of tissue grew into the gap from the top by the time each tree died about 12 to 18 months later. It isn't how wide the gap is. It's whether a continuous band around the trunk at least an inch wide-we go about four inches because it's easier than dealing with narrower bands-is meticulously clean of any tissue that can grow new phloem and bark.
Chainsaws cut too deeply and produce a stump that resprouts. Besides, this video is for training volunteers for the city of Austin, and they can't use power tools or herbicides. This technique works beautifully under those restrictions. It's quieter and the tools are a lot lighter, too. 😀
I forgot to mention three other points earlier. Cutting the tree down doesn’t kill the root system, so the tree sends up many new stems where there had been one. Even when the stump is treated with herbicide, the success rate has been less than 100 percent. (This video was commissioned to teach the method to volunteers after the city saw that my volunteers using this technique were much more successful than were their contractors using chainsaws and herbicide. Second, unless you dispose of the fallen tree right away, branchlets in contact with the ground can reroot. The girdled tree can stand until it falls apart, and its decomposing branches and trunks can become humus, enriching the soil. Third, where contractors cut privets down, the lighting conditions went from the deepest shade to full sun overnight. The sudden exposure to full sun killed nearly all the plants that had been struggling in the privets’ deep shade. Topsoil-and, with it, the seedbank-washed away. Ten years later, the areas still haven’t recovered. In the acreage where we’ve girdled all the trees, the understory thrived. Canopy-level species have established a new woods. In the one area where saplings were planted to restore cover, the result was an overplanted area, We had to dig up many of those saplings and move them to locations where they were actually needed-for example, areas where the original canopy was nothing but Ashe juniper. So we get a higher kill rate, we have no brush to dispose of, and the desired native habitat reestablishes itself without our having to do a thing. You can’t get those results with a chainsaw.
To do it right, don't overlook all these key points:
0:00 background
1:15 how girdling works
2:10 technique: initial cut
3:10 technique: peeling
4:15 technique: cleanup with blade
5:55 technique: cleanup with abrasive pad
6:45 technique: cleanup with alcohol
8:10 treating the whole tree
Good Job, Cliff! Very thorough. I usually use a saw to make the initial cuts and a 5-way tool to peel the bark. A really sharp 5-way tool. Don't usually spray after if I take the time to insure all the cambium is gone. This is not as easy as it looks, people!
I guess I can’t post pictures here, but I checked these trees out March 4, 2020-about 7.5 months after I had girdled them-and no tissue had grown in the gaps and no sprouts had formed below the girdle. (After the video was done, I stayed and finished girdling all 7 of the other trunks on this tree, two of which were hidden behind the others.)
I think this comment got cut from the video, but it's important: When you're peeling the bark and phloem away from the trunk, you won't see the difference in color that shows up in the video. On camera, the beige shade of the exposed sapwood and the bright white of the phloem are easy to distinguish. With the naked eye, both seem to be ivory-colored. It's easy to miss seeing that you left a lot of phloem behind. On the other hand, if you leave the girdled trunk alone for a few minutes, both the phloem and the cambium on the surface of the sapwood will darken. Better yet, they will darken to different shades of brown. Then it's easy to see what's left and to know when you've finished removing it. So when I girdle a multitrunked tree, I will do all the work with each tool before going to the next tool:
1. Circumferential cuts with the carpet knife-on every trunk.
2. Peel away the bark and phloem with the putty scraper-on every trunk.
3. Now that the trunks are darkening, start with the first trunk I peeled and do a quick follow-up scraping to remove the big pieces of phloem-on every trunk.
4. Starting again with that first trunk, scrub with soapy water and a coarse scrubbing pad-on every trunk.
5. Again, starting with that first trunk, scrub with rubbing alcohol (70 percent isopropyl alcohol; check the label) and a finer scrubbing pad.
If a tree has only one trunk, I will girdle several other trunks at the same time, working through the same sequence. By giving each trunk a few minutes to age between steps, I make it easier for me to see the tissue I need to remove.
I'm glad I found this! I've got invasive scrubby overgrowth, and it's cut it back, it regrows, repeat. Going to do more research on this technique.
You might find other videos on girdling, but I can save you some time. Once way or another, I have tried all those techniques, and they haven't given the success we've had with this technique. On one area we followed rigorously so we could report the results to a sponsoring agency, we had a 99.7 percent kill rate at 2 years after completion of the year-long project. That's close to 300 trees, and only one still alive 2 to 3 years after we girdled it. I did in the meantime monitor the results every 3 to 6 months and fix the few trees on which the technique had not been perfectly executed at first. I have seen only one large-scale study that documents a success rate even approaching this. In that study, the researchers used basically the same technique. (They did not scrub the sapwood clean. Instead, they vigorously scraped all the phloem and cambium away. I've done that. It does work, but it's a lot more difficult and significantly less successful-perhaps 90 to 95 percent instead of better than 99.7 percent-or requires significantly more followup work to get a comparable rate of success.) I have seen many studies of the impact of girdling on trees in which the overall success rate was no better than 50 percent. Generally the point of those studies was to see how different species respond to girdling, or how trees of the same species in different settings respond to girdling, or how an aspect of tree growth was affected by girdling.
Thanks for this video. It was very helpful. I started experimenting with girdling black locusts a couple of years ago on my property. I girdled them in the fall. I didn't realize that the girdling should be done when the trees are leafing out to put additional stress on the root system. That seems really important. I got robust sprouting from my girdled trees below the girdle.
Cliff is my hero
Excellent work. Good job
Is this method used specifically because of aversion to herbicides? A hack and squirt approach would take a fraction of the time and effort.
II developed this method so Adopt-a-Creek volunteers could tackle this and other invasive trees on the segments they care for. Without proper licensing, liability insurance, and a signed contract, the city won't allow us to use herbicides. Of course, then we would be contractors, which takes all the fun out of it. (Power tools are also forbidden.)
We do have a city employee who is licensed to use herbicides, but our many volunteers can make far more progress than he ever could. We can use a wide variety of people-8-year-olds to do the scrubbing; Scouts with their Whittlin' Chip to make the cuts (although we actually restrict that to 18-year-olds unless a responsible adult who brought the youth is supervising closely); office employees looking for a different way to spend a day volunteering in the park; fraternital organizations; so many others.
We've noticed another advantage over areas where a thick infestation is controlled with herbicide. The herbicide kills the treetop so quickly that native plants that have been struggling in the deep shade beneath the privets often burn up in our hot Texas sun. But a girdled tree shows no symptoms for weeks or months, then shows drought stress (wilting over the course of the day, then rejuvenating at night), and eventually starts dropping leaves. It's hard to assess how much light reaches the ground by the time the root system dies, but in a study in which about 40 trees died, there tended to be only 30 to 70 percent open sky when looking up from the base. So the tree was still casting mottled shade at the time the root system died.
Under those conditions, many saplings and plants have responded well to the slowly increasing levels of light. The oversized, soft leaves of a tree struggling in deep shade were replaced with increasingly (?) smaller, more leathery leaves characteristic of a species adapted to direct sun. We generally don't have to replant, unless we want to adjust the habitat. In many of the areas where herbicide was used, the city struggled to reestablish a native landscape in what had become a barren space. Again, barren not because of herbicidal drift, but because of a change from deep shade to full sun over a few days to a week.
That's a benefit we weren't expecting. (In the few places where we don't see many woody species or understory plants reestablishing themselves, I suspect the area was a meadow before the privets moved in.)
I was going to ask the same question, but what a great response Cliff. I mean, it's very labor intensive, but does seem to do a great job where one must abide by rules and such. I'm taking on a huge invasive project on my 160 acres in Kansas. We could never work this slowly. I'm hoping for the best. Im working with our state forester and local NRCS office for a true Cross Timbers restoration.
It’s especially important to be thorough when you can’t get back to the trees easily. But if you can get to the trees easily, then you might be able to be less thorough on the initial job and follow up later on only those trees that show signs of recovering. Especially when hot, dry weather follows your girdling project this might save time.
Last weekend my cutters and peelers got way ahead of my scrubbers, so I have 50 trees (202 trunks) done and more than 100 trees (and probably at least 300 trunks) that have had a collar removed but have mot been scrubbed. Because they’re all within sight of a trail I hike at least once a week, I can keep an eye on the progress of those incomplete trees and follow up as needed. We’ve had dry weather, so maybe I’ll be lucky and much of the residual cambium will dry up and die on its own. But often it's such a pain to even get to the trees that I want to be sure to get it right the first time.
@@clifftyllick8529 Question for you: I imagine this is not part of your process at BCP, for multiple reasons, but at what point after girdling would it be okay to cut down the tree if desired? I think my first attempt at girdling a mid-sized chinese privet in our NTX yard is succeeding thanks to watching your video. Girdled it last May and now all of the leaves have dried up and started to fall (including on a couple small sprouts below the girdle line, which seems promising). Going to plant some native shrubs nearby and would like to cut it down, but only once it's done exhausting the roots to avoid new sprouting.
Just go around the base with a strimmer, a method used to kill perfectly good trees by council workers tidying up the grass verges in the UK.
Of course that works on young, thin-barked trees. And to young trees maintenance crews are more lethal than rodents.
If the string trimmer weren't a power tool, we could use that approach. But our volunteers can't use power tools. (That's a bonus: without power tools, misguided volunteers can't wreak nearly as much havoc as your maintenance crews do.) Besides, the trees we work on have an average of 3 trunks each. Many are single-trunked, but the multiple-trunked trees usually have at least four trunks and often have more than a dozen. There is a lot of phloem included between the trunks at the base, so the line trimmer would be completely ineffective there. Where the trunks do eventually separate-usually waist high, sometimes over my head-it's hard enough to slip a cutting tool between them. You'd have no chance with a line trimmer.
Your (no doubt facetious) suggestion illustrates how wrongheaded it is to use a chainsaw or any other tool that cuts deeply into the sapwood,. A monofilament line just a millimeter or two thick can only remove the bark, phloem, and cambium from the base of a young tree. It couldn't even bruise the sapwood of most woody plants. Normally you would have to remove a band wider than 2 centimeters to ensure that the gap doesn't heal over before the tree dies, but in your case the maintenance crew returns regularly and reestablishes that gap, so if it bridges at all it doesn't remain bridged for long. Eventually, the root system will starve to death and the tree will die.
All you (or, in this case, our wonderful landscape crews) have done is to remove that one layer that carries the sugar. No need to rip into the actual wood. The sapwood isn't where the work needs to be done.
This works, but its labour and time intensive. Hack and squirt for the win.
what product is best to squirt with :)
@@joanneshepard5449 roundup or garlon usually.
@@joanneshepard5449 Research it on here silly!
I would never put a herbicide on my land
In many settings, either herbicides are not allowed or, as in my case, volunteers are not allowed to apply them. With hundreds of acres to cover, the biggest drag on progress is the time required to monitor success and remediate failures. We've had a significantly greater rate of success with this method than contractors using herbicide have had in their work. Your mileage may vary.
Cliff, I'd like to harvest the canopy for my goats to eat. In the video you explained that the leaves need to remain to put a stress on the tree of trying to pull sugars up out of the ground to thoroughly kill the tree. Is there a midway point here? Can I leave a branch to still create the demand in sugars while taking the rest for my goats?
Hi, Jenny! The short answer is no, you can’t let your goats eat any significant amount of the canopy.
Let me correct a misconception, too: The canopy gets water, not sugar, from the root system. The root system starves because we’ve removed the tissue that resupplies it with sugar made in the canopy.
For this to work, we can’t give the tree a chance to grow new shoots from below the girdle. So long as the canopy above the girdle demands every drop of water the root system can produce, the base of the tree won’t be able to grow new shoots. It will try, but the shoots won’t thrive because the treetop is using all the water. If we reduce the canopy, the tree will be able to support the growth of shoots from below the girdle. Instead of staying thin and green, the shoots it forms will thicken, cover themselves with bark, and keep growing. With the sugar produced in their leaves, the root system no longer starves. The tree survives.
Thinking this through, though, maybe you shouldn’t girdle the trees. Cut them at the ground, feed the canopy to the goats now, and then let the goats graze on the new sprouts from the live trunks. The goats will keep the privets from ever getting big enough to flower and might eventually kill each of them outright.
See, usually the problem with cutting privets to the ground is that we can’t stay ahead of the new shoots sent up from the stump. If we could strip off every one of them as soon as it formed, we could kill the tree in a year or two. Most of us could never do that.
You, on the other hand, have an army of goats to do that work for you. See if it works!
Jenny, in my first answer, I forgot a very important aspect of this: Where we have thick infestations of glossy privet, we also have many younger trees, small enough we can uproot them, but still over 10 feet tall. That's a lot of browse for a goat! So the girdled plants can't provide the browse, but I have plenty of places where we would need to dispose of a trailer load or so of uprooted smaller trees. In fact, we sometimes have to uproot a thicket of small trees to reach the tree we have to girdle. Do you happen to be near Austin?
Could one use a cordless angle grinder with a sanding disk to remove the cambium? Thanks for showing a safer way to get rid of the trees without the potential for harming my oaks.
Grinders and sanding disks are designed to work well on dry wood. The live tissue will gum up the disk or grinder. When I was experimenting with ways to make girdling always work, I first tried sanding pads and wood rasps. They gummed up before I had cleaned even a 4-inch-diameter trunk.
Another problem with rasping tools-and with power tools in general-is that you can’t tell when you’ve finished removing phloem and cambium and are starting to grind into the sapwood. If you remove too much sapwood, the basal sprouts always produced by girdled trees will thrive. Those thriving shoots will keep the root system alive, which will make the girdling fail to kill the tree. The grinding surface will also embed bits of phloem and cambium deep into the sapwood. That embedded tissue will find plenty of water in the sapwood to keep it alive, and it will more often than not grow into new cambium, phloem, and bark to bridge the gap. Again, the girdling will fail.
People always want to use power tools in the woods. They're loud, heavier, and more cumbersome, and they don't work nearly as well. A friend of mine who is a plastic surgeon told me that this technique is a lot like his work. He has to lift layers of tissue and separate them, intact, from the adjacent layers. In both cases, the best results are produced by probing between the layers with a dull tool and then lifting the layer that is to be removed. It might help to keep that in mind. We aren’t butchering a carcass into pork chops. We aren’t sandblasting old paint and rust off a metal post. We aren’t cutting tile or polishing stone. We’re doing surgery, or at least a dissection. We’re lifting a layer of tissue from a living organism. For greatest success, we need to keep that layer intact as we work, and we need to leave the layers beneath it as close to unscathed as we can manage. Power tools won’t do that.
@clifftyllick8529 This is great too because especially for commercial jobs, the balcones canyonland preserve in this area has the golden cheek warbler (bird) protections up which wont allow you to use power tools during the coolest months of the year. (ideal sawing times) -or if you're close to an HOA that has bans on noise. -It's one more tool in the toolbox to solve problems with low tech tools that are readily available to everyone.
Cliff this a great video. I have a question. What happens if you cut too deep? I think I may have cut too deep on one of the trees.
Hi, Beaux! It depends. Scratching into the xylem has almost no adverse effect. Cutting a quarter-inch into the sapwood of a 12-inch trunk will also have almost no adverse effect. But cutting an extra quarter-inch into a 1-inch trunk will let the base of the tree live while the top dies. In the long run, it would be as if you cut the tree off at that level instead of girdling it.
By now, you should be able to tell whether your cut went too deep:
• If it did, the sprouts that (almost) always form from the trunk below the girdle will have put on bark, grown to more than a few millimeters wide, and continued to grow in length and girth. (Those sprouts are called basal sprouts.)
• If it wasn't deep enough to cause problems, those basal sprouts will still be no more than a few millimeters wide, probably will have no hardened bark on them at all, and instead of continuing to get longer and thicker might actually be withering at the tips. They might be four or five feet long, but they won't be thickening at the base and probably won't get much longer than that.
If the basal sprouts are hardening and growing thicker, the problem could also be that you left tissue bridging the girdle (or, if you had to girdle more than one trunk on the same tree, any one of the girdles). So if you see that, the first thing to do is to look for bridging tissue and, if you find any, remove it. Don't just scrape the exposed bark off of the new tissue, because there is almost always some new phloem between that bridging tissue and the original sapwood. You have to remove that inner phloem, too. After you have removed the new tissue, girdle all sprouts that are at least a centimeter or so in diameter and strip away all of the weaker ones.
If you don't see any bridging tissue, then the problem is probably that you did cut too deeply. crazy as it might seem, you now need to let at least some of those woody sprouts continue to grow. Strip off all but a few that are spaced widely enough that it will be easy to girdle them. Let them grow until some time next summer, and then girdle them. (You can do something right now to make sure it's easy to girdle between each of those new shoots and the original trunk: jam anything between the shoot and the original trunk to create a gap between them.)
Here's more about what's going on. Botanists describe trees as "ring-porous plants." That makes sense when you think of the cross-section of the tree-the sapwood is a series of lighter, more porous rings separated by darker, less porous rings. Water wicks through those rings from the roots to the treetop. The outermost layers carry the most water, and the innermost layers might carry none at all.
The problem with cutting into the xylem arises when you go deep enough to significantly reduce the flow of water past the girdle to the top of the tree. That's why scraping a little sapwood off rarely matters, and that's why I can't give you a precise answer as to how deep would be too deep. As I suggested above, the only way to know if you've cut too deeply is to observe the tree and see if the base starts recovering. A proper girdle will kill the base before the treetop dies. If the base looks better than the treetop, something is wrong.
A few points more:
• I know from experience that cutting too deep can be a problem. I have seen trees that were dead from the girdle up and still alive-and thriving-at the base. On those trees, at least one of the circumferential cuts went much deeper than necessary into the sapwood.
• I would like to explore your question in my next experiment: How much is too much? What difference does it make in the fate of a 2-inch tree if you just scratch the surface? If you cut 1/4 inch into the xylem? 1/2 inch? What about a 4-inch tree? Or a 10-inch tree?
• Above, I told what to do when you see the basal sprouts thriving. Other than those cases, I never strip any basal sprouts from below the girdle. They are like signal flags I can see from ten or twenty yards away-if they're wimpy, everything is fine. If they're getting vigorous, I need to get over there and see what's wrong. So long as they stay wimpy, they will die on their own when the base of the tree is dead. I shouldn't waste time removing them.
• I implied above that when a girdled tree thrives there are more than these two possibilities-a bridged girdle and a cut made too deeply. There is a third: the tree is interconnected to another glossy privet through its root system. I have not seen evidence that separate privets will connect their root systems, but I have seen instances in which the exposed root of a large privet produces a sucker, sometimes 5 or 10 feet away, and that sucker grows to the size of a tree. I've also seen cases along streams in which a ligustrum got toppled by a flood and buried in sediment, and then each of its exposed branches grew into a trunk. In those cases, just as with a tree that has 5 or 6 trunks growing from the same base, you have to girdle every trunk on the same root system before the tree will die. For me, this has been very rare, but in some other setting it might be more common.
Beaux, thanks for asking!
That was so nicely done you could have signed it.
Occasionally I do. 🤣
Excellent
Hey, I see you're operating a fruit farm. As you know, you can girdle an individual branch on a tree to make the fruit on that branch grow larger and sweeter. That technique also fails if any connection across the girdle remains. The same technique I described here would ensure that the girdle is done properly in that setting, too.
@@clifftyllick8529 hi please if idid like this cutting the skin of my avocado tree like that will this operation will make it give fruits please?
Sorry I didn’t see this earlier. On a fruit tree (avocados are fruits), you could do this on an individual limb to get sweeter, larger fruit on that limb. Don’t do it to the trunk because you would then kill the whole tree.
For an added effect, strip half to two-thirds of the fruit from the girdled branches.
Would this technique work for prepping a branch for airlayering too?
If by air layering you mean packing the soil or other growth medium around the girdled section, I think it could work. Because girdling prevents sugars produced in the branch from being returned to the root system, there would be more sugar available to grow roots in that medium. Just be sure to pack it around the upped portion of the gap and a half inch or so of the bark above the gap. In this case I don't think you would need to scrub the gap clean. Even if there is a trace of tissue bridging the gap, there will still be a lot of sugar that can't get through, and that sugar would be available to support vigorous root growth. At the same time, because you haven't damaged the sapwood the branch would be receiving every bit as much water as before.
Girdling could also improve results with layering by bending a branch down and burying a node or two In this case, you would girdle between the node or nodes you bury and the rest of the plant. Again, the branch would continue to receive as much water as before, and the sugar that can no ;longer travel to the roots would be available to support the growth of the new roots from the buried nodes.
Thanks for asking! You've given me a couple of ideas for propagating native plants not easily found in commercial nurseries.
@clifftyllick8529 wow now that's a loaded explanation 👏. Thanks a bunch! Do you have a RUclips channel that I can enjoy & learn from more content like this?
Great video and info. I'm wondering if this would be a good time to start girdling more of them, given the stress they've had with the last month's freeze. Or would it be better to wait a few month until they've pumped their carbohydrates to grow new leaves and then girdle them to burden them at that point?
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Have you ever tried spraying with salt water, and could that work? Rubbing alcohol right now is precious right now for our household during COVID, so am looking for short-term alternatives.
Great questions. From Cliff: By all means, girdle now! So long as you have all the necessary permissions, the best time to girdle a privet is whenever you're standing next to it with the tools at hand. As said in the video, scrubbing with soapy water is enough by itself if you clean the gap thoroughly. You could use any gentle cleaning agent, either alone or as a second scrub. The most important thing is to check your work again before you leave. The xylem will stay light colored. If you see anything turning darker brown, scrape or scrub it away.
Does anyone know if this will work for tree of heaven (aka tree of h_ll)?
I do not, and am very interested to find out. Fortunately there is a dearth of TOH (Ailanthus altissima) in my immediate area.
My guess is that it might work on trees that have not yet produced root suckers. On two Callery pears that had recently produced suckers-that is, the suckers were no more than 3 feet tall-both the main trunk and the suckers died, even though the suckers had not been girdled. (Until they died at the same time as the main trunk, I hadn't realized that the adjacent sprouts were suckers.)
Good farming.. 👍😎
My dad just asked me translate this video for him but i am confused why would you want to kill a tree!?
Thanks for your question, Yasmine. This technique is used to control the invasive tree, Glossy Privet. Glossy Privet (aka Ligustrum) is an invasive species that will spread to take over an area and shade out and kill other beneficial vegetation. Because it is destructive to local ecosystems, we work to control this species on the Balcones Canyonlands Preserve by girdling large Glossy Privet and pulling out seedlings. Girdling allows native seedlings to establish and replace the Glossy Privet canopy as these non-native, invasive trees slowly decompose. Before girdling a tree, it is very important that a person correctly identifies a tree as Glossy Privet, so as not to a harm non-invasive trees. To learn more about how to identify Glossy Privet and other invasive plants, visit:
www.austintexas.gov/sites/default/files/files/Watershed/invasive/2013_Invasives_guide_small.pdf.
We love native trees and plant many new trees on the preserve every fall and winter. To learn more about the many benefits of trees and how to plant a tree, check out our other videos in our Forest Restoration webinar series: ruclips.net/p/PLUg_t5WZwkb9qp7xVtgbtD2JMqS8D8ko5
@@austinwaterwildlandconserv8336 thank you so much for your thorough explanation i appreciate it.
@@yasmineset7045 great question. Thank you for asking!
Girdling also has other purposes. In some countries, girdling is traditionally used to create standing deadwood for heating or cooking fires. Wood in the air is easy to reach, stays drier, and is less likely to rot before you gather it.
On tree farms, I understand that some otherwise desirable trees are girdled to thin the crop and let other trees grow as desired. I don't know how frequently tree farms would do that.
As I mentioned in another reply above, girdling is also exploited in fruit orchards. In that case, they girdle one or no more than a few branches on a tree to block the transport elsewhere of sugars produced by that branch. That results in larger, sweeter fruit on that one branch, because the sugars (and related metabolic substances) can't be used any other way. I don't know if that method results in the death of the branch. Because other branches keep feeding the root system, the girdled branch might well continue to survive. I'd have to ask a fruit farmer.
Yasmine, I forgot to ask: What language did your father need?
How long will the tree die after this girding? And you wld still need to cut down the dry trunks?
"grim reaper of ligustrum" 😂 -that's my line! -or I guess that make me the "Prince of Privet-Destruction" or the "Annihilator of Arundo Donax" 😂 -Fight the good fight ya'll!
"-The Justiciar of Johnson Grass has weighed and measured your monoculture and found it wanting..." B\
LOL! Keep up the good work!
Nice technique, problem being you're creating possibly a handful of widow makers. talking for consequently sized trees of course.
Three factors reduce that likelihood. One is general, and the other two are particular to glossy privet. I'll start with those that apply to glossy privet.
1. In our setting, because the glossy privets are either growing through the canopies of deciduous trees or densely packed among themselves, they can't fall. When we have cut the dead trees, we have had to pull them out of the canopies. A few have been so intricately interlaced in the deciduous canopy that we couldn't drag them out.
2. By the time a glossy privet is rotten enough to fall on its own, the top is so dry that it is too light to do much damage and so brittle that the impact would be absorbed by the breaking of the small upper branches. (Glossy privets don't have a lot of mass up high anyway.)
3. Girdling works by making the canopy a parasite on the root system. It uses all the water the root system can produce and provides no sugar in return. The canopy remains alive-somewhat thinned, but still alive-until shortly after the root system dies. You'll know when the root system dies because the basal sprouts will die with it. At that point, the tree is still sturdy. Because the root system is dead, you can cut the tree down without triggering new sprouts.
Girdled lots of hardwood with an axe, much faster and less work.
On glossy privet, the axe will cut too deeply, and you’ll get vigorous regrowth from below the girdle. In other words, the tree will survive. This method is extremely effective for eradicating infestations of invasive woody plants. It does depend on your goal: Reduce the number of trees of a certain size or species? Or kill absolutely every tree with the goal of eradicating its species? Kill just the aboveground portions of the tree? Or kill the entire root system, so there are no resprouts from the base and no new suckers after the top dies?
It also depends on how frequently you can return to the area to check results. We have so many acres to cover that I can’t waste time checking up on our past work. I typically check the quality of work within a week and then check the progress once, 6 months to a year later. Every tree we girdle dies. And the root system dies first, so there’s no way the trees can regrow.
I am India....
I don't get it. Why not just use a chainsaw. It would have same effect and would take only 20 sec instead of 20 minutes.
The video explains why and how girdling works. Chainsaws are useful for cutting off large branches and cutting down large trees. Cutting down a tree doesn't necessarily kill it. Doesn't kill camphor trees, redwoods, melaleucas, eucalyptus, Brazilian peppers, and many other species.
Interesting. I've killed many a tree by simply digging down to a large a root then drilling a 2" bore hole in it and pouring in the resulting root "cup" 4 ounces of 41% glyphosate (Roundup). This will take out any tree under 24" in diameter. It takes about 2 months. For larger trees, treat more than one root. T-i-m-b-e-r!!!!!
- You can also find an apron feeder root and insert the small root fingers in a glyphosate water bottle. Soon the root will empty the bottle (Thinking that the liquid death is water).This also works well; but not as fast.
Our volunteers cannot use herbicides, so your technique won't work under our conditions. We can put dozens of willing and eager volunteers into the field and make steady progress in large areas. In fact, the city asked us to make this video because we were outpacing the licensed employees who were applying herbicide, and we actually get a better kill rate. So their employee can do other tasks, which is a big boost given their severely understaffing issues.
If you prefer to use herbicides, you should instead use the better, more efficient approach called frilling or sometimes something like clip-and-drip. You make cuts into the phloem, not the sapwood, in alternating locations around the trunk and trickle or daud the concentrated herbicide onto the phloem. With a proper application of the herbicide, there is no dripping or overspray. Your 4 ounces of concentrated herbicide could do a dozen trunks or more, not just one. An agency in Pennsylvania describes that technique clearly for killing tree-of-heaven. If you search for their flier you'll find a way to save time, material, and money. (For one thing, there is absolutely no reason you need to dig down to find a root. You work on the trunk at whatever height is accessible to you and comfortable for you.)
To have an effect on the plant, herbicide applied to sapwood must first travel to the phloem. The thicker the trunk or root and the farther you go into the sapwood, the less of your herbicide makes it to the layer where it does its work. Again, applying the herbicide properly, you can treat more invasive plants with less work and far less chemical.
Why are you being so maticulous ? Why be concerned about the trunk, just go deep?
I developed this technique by studying why that very approach did not work. When used by half a dozen volunteer groups that I knew of and, in the same program, by quite a few more, cutting into the sapwood produced 100 percent failure. There were four reasons for this.
First, even when they cut into the sapwood, they also left strips of phloem connecting or nearly connecting tissue above the girdle to tissue below the girdle. Those trees quickly recovered.
Second, if they cut too deeply into the sapwood, the flow of water to the treetop was restricted at the girdle. The base of the tree produced sprouts that thrived. The top of the tree died quickly-sometimes within a few weeks. The root system remained alive. Instead of having a dead tree a year later, we had a thriving tree with 5 to 15 times as many trunks. This often happened on trees on which each trunk was no more than about 3 inches in diameter.
Third, on larger trees, the layer of phloem is thick enough and woody enough that people think they're cutting into sapwood when they haven't even gotten through the phloem. "I know I got it right, because I cut into white wood," one volunteer told me. Those trees form new bark within weeks. If you look closely, you can see a difference in the surface of the bark where the girdle was, but the tree was not noticeably set back.
Finally, even when we meticulously got between the phloem and the sapwood with the scraper and peeled a full 4- to 6-inch-wide collar of phloem away, bits of phloem sometimes remained behind and a film of cambium always remained behind. If the weather was not hot and dry, that residual tissue was usually able to grow a new bridge of phloem and bark across the gap before the tree died. Scrubbing the phloem and cambium away without cutting into the sapwood turns out to be the key to a reproducibly high kill rate.
I tried many variations-making sure to cut deeply into the sapwood; scraping the residual tissue away (effective if done meticulously, but slower than scrubbing, and requires such vigorous effort that I needed to ice down my hands, wrists, elbows, and shoulders after each workday); removing a narrower band of tissue (actually more work, because it gives us less leeway in working the scraper under the bark); removing a wider band of tissue without scrubbing (one group removed strips 2 feet wide on several dozen trees-with 0 percent success); and more. Each of those variations either failed or was far more difficult. This works.
Also, when we do this with a group, we can speed the process up by having one group start early and do the two cuts, another group come behind and do the peeling, a third group scrub with soapy water, and a fourth group scrub with alcohol. This lets us add volunteers who can't be trusted with sharp tools. For example, folks have brought their 8- to 12-year-old kids to do the scrubbing. They do a great job. With more sets of eyes examining the quality of the job, we have fewer failures for me to find and fix in the next few months. The volunteers really enjoy it!
@@clifftyllick8529 thank for such a detail response. 👍
You're welcome, @@PatrickDenehy-f4k ! Thanks for asking.
Insanely labor intensive and you are still spraying a chemical.
You're right about the chemicals. Even water is a chemical. But our volunteers are not allowed to use herbicide, so we use common household chemicals that are essentially inert. Soapy water and rubbing alcohol release different kinds of gluelike substances in the bark and make the peeling somewhat easier.
Working with various groups of 12 to 40 volunteers 5 to 10 times a year, we killed 99 percent of the mature glossy privets on about 30 acres and uprooted the next generation on 10 of those acres in 2 to 3 years leading up to the pandemic. Once we get to the entire park, we will have plenty of time to uproot or girdle that last generation before a single one of its privets reaches maturity. Because teenagers can do the cutting and peeling and kids as young as 8 can do the scrubbing, we have been able to lead high-school science or service clubs, Rotarians, youth sports teams, families, Scouts, companies wanting something unusual for team-building events, groups on leadership development retreats, fraternal organizations working as part of a reunion, science clubs, and more. Insanely labor intensive? Maybe, but our volunteers come back eagerly. Please don't tell them!
If you have the training, certification, and equipment required to use other methods and cannot get access to volunteers, go for it. But we're getting great results under the conditions possible for us, so we'll stick to this approach. It's essentially free, it's highly effective, and it builds a sense of ownership of and appreciation for our green spaces among the people who use them.
9" removal of bark, nothing else needed.
We've had one large group remove 12 inches of bark without following this method and another remove 24 inches. Both had failure rates of 100 percent. If you damage the sapwood too deeply, the top dies before the root system and the trunk produced many new sprouts. A year later, you have a multitrunked tree to deal with. If you don't scrub the residual phloem and cambium from a band at least 2 inches wide, the trunk will cover itself with bark again in a matter of weeks.
I had one volunteer who peeled all the bark and phloem off three large trees-a total of 10 or 12 trunks-from chest-high (not quite 5 feet up) all the way down to the ground level. Each looked like nothing but bare sapwood was left. A week later, the entire length of each trunk was covered with regenerating tissue. Trees left like that develop new bark over the whole area in a matter of weeks. Of course, they survive. I scrubbed a band 2 to 4 inches wide around each of those trunks. The rest of the areas finished covering themselves with bark. As is usually the case, little if any new tissue grew into the girdle from below and just over 5/8 of an inch of tissue grew into the gap from the top by the time each tree died about 12 to 18 months later.
It isn't how wide the gap is. It's whether a continuous band around the trunk at least an inch wide-we go about four inches because it's easier than dealing with narrower bands-is meticulously clean of any tissue that can grow new phloem and bark.
I'd girdle it with 1 cut of a chainsaw - stand clear and enjoy.....
Chainsaws cut too deeply and produce a stump that resprouts. Besides, this video is for training volunteers for the city of Austin, and they can't use power tools or herbicides. This technique works beautifully under those restrictions. It's quieter and the tools are a lot lighter, too. 😀
I forgot to mention three other points earlier. Cutting the tree down doesn’t kill the root system, so the tree sends up many new stems where there had been one. Even when the stump is treated with herbicide, the success rate has been less than 100 percent. (This video was commissioned to teach the method to volunteers after the city saw that my volunteers using this technique were much more successful than were their contractors using chainsaws and herbicide.
Second, unless you dispose of the fallen tree right away, branchlets in contact with the ground can reroot. The girdled tree can stand until it falls apart, and its decomposing branches and trunks can become humus, enriching the soil.
Third, where contractors cut privets down, the lighting conditions went from the deepest shade to full sun overnight. The sudden exposure to full sun killed nearly all the plants that had been struggling in the privets’ deep shade. Topsoil-and, with it, the seedbank-washed away. Ten years later, the areas still haven’t recovered. In the acreage where we’ve girdled all the trees, the understory thrived. Canopy-level species have established a new woods. In the one area where saplings were planted to restore cover, the result was an overplanted area, We had to dig up many of those saplings and move them to locations where they were actually needed-for example, areas where the original canopy was nothing but Ashe juniper.
So we get a higher kill rate, we have no brush to dispose of, and the desired native habitat reestablishes itself without our having to do a thing. You can’t get those results with a chainsaw.