Hello, everyone, my name is Liz Moss. I'm an urban forestry extension agent with the West Virginia State University Agriculture and Natural Resources Extension Service. And today I'm going to be talking to you about tree pruning for beginners. So consider this a crash course in tree biology as it relates to pruning, and why we make the cuts that we do. So we're going to cover some basic principles of pruning. And this presentation is part of the West Virginia Tree Minders Online Tree Care Certification Program that is in partnership with the West Virginia Division of Forestry, Urban and Community Forestry Program. So this is a course that you can take on your own time and engage in some assignments, and also have available to you various outdoor supplementary demonstrations or outdoor workshops to actually put some of these skills into practice. So let's begin.
So let's first start with a discussion about what exactly is pruning. The definition is the selective removal of tree parts to achieve specific maintenance objectives, namely to improve health, safety, aesthetics, and ultimately the structure or function of a tree. And so all three of the former ones actually feed into the last: structure and function. That's what we're trying to do. And you'll see that I'm going to be focusing mainly on training young shade trees that are going to end up being of medium to large mature height. So we are trying to correct issues with any smaller trees, that will become a bigger problem in the long run and require professional intervention. So small cuts do less damage. It's better to correct defects on these trees when they're young and vigorous. And we are trying to basically save ourselves time and money in the long run.
Some basic principles of printing, keep in mind that each cut creates a wound on the tree that will stay with it for its life. It also changes the growth of the tree. If you remove one branch, the tree will end up diverting resources to another branch to take over dominance, or it will have more resources to distribute around to other branches. It also removes food production capabilities, we are reducing for the synthetic capacity by removing life foliage. So with these things in mind, please always have a purpose in mind before making any kind of cut because poor pruning can cause damage that lasts for the entire life of the tree.
Continue on, so winter is the best time to prune. And that is for a variety of reasons. Namely, trees are dormant, they have shed their leaves, they have stored any starches and any energy reserves in their wood and are basically taking a big long nap for the winter, your deciduous trees are. They're leafless so we're able to see their architecture or structure. It's more visible and accessible, especially when training on trees. You can see the tree on the right hand side here, that it's pretty messy and maybe with the leaves covering it you might not be able to see that structure. Also pests and disease are typically less active in the winter months. And also we are maximizing time during the growing, the following growing season where the tree to be able to seal up any wounds that we create. So we don't want to trim trees too early in the winter because cuts can dry out if the temperature drops well below freezing and stays there. And we also don't want to prune too late in the winter. We always want to prune before buds swell. That's before the tree starts moving its starches out to the buds and is preparing to leaf out. So at this point, sap is running up a lot and any wounds that are made to the tree is going, are going to cause a lot of weeping wounds, sap loss, which is also energy loss.
So any time of year, we can prune the three D's, dead, damaged or diseased branches. And there are some exceptions to this rule, like in the case of oak wilt, if you're pruning any kind of oaks, try to limit them that pruning to the dormant season. We never want to prune oaks in West Virginia between, I would say easily, April through October, it's just just not a good idea. Because oak wilt is an exotic fungal pathogen that is active during these months and can be spread by sap feeding beetles that are attracted to open wounds on oaks. So we want to avoid any kind of wounding of oaks during this time.
So I talked before about how whenever you make a pruning cut, the wound is with the tree for its entire life. And that's because trees compartmentalize any kind of wound, or in order to prevent decay from spreading, so they don't heal, they seal. Any one that you make, it's just going to be covered up and incorporated into the wood as the tree grows. And if you were to take a cross section of the tree, you would see that old wound in the case like in a dark stain of sorts. So this is why it's crucial to know where to make pruning cuts on trees in order to minimize damage and stress response. So in this graphic here, on the right hand side, you'll see the numbers one through four. And these represent like walls of a box if you will, like a cube. This is what your compartmentalization looks like inside of trees. So wall one is the one that runs longitudinally through the length of the tree stem or branch. It is the weakest wall, and I'll talk about that in just a moment. And it prevents decay from spreading up and down the home of the tree or branch. Wall two prevents decay from moving into the center of the tree where the heartwood is. Wall three prevents decay from spreading radially around the width of the tree or the girth of the tree. And as represented by these rays is lines coming in, perpendicular to the growth rings. And wall four is the wall that is made between old wood and newer wood. So wherever that wound occurred, while four is going to be the strongest preventing that decay from making its way into newer tissues, especially that cambium layer, that living tissue layer on the outside of the wood underneath the bark.
Here's a cross section of a peach tree showing these walls in action. You're not going to see wall one, because this is just one section from cookie, one cookie, if you will, because wall two doing its job, there's a little bit of movement of that decay into the center of the wood, but not, not too bad, wall three as well. Wall four is doing such a good job that as this cookie has dried that, that wall is the wood has actually dried and cracked and separated. So you can see how strong that wall four is. And wall one is why trees are able to stand hollow, and still be functionally alive, that outer layer that is protected by wall four, that cambium layer is still alive, that is the vascular tissues of the tree and allow it to continue to live. But structurally, the tree is severely weakened and it has that column of decay from that wall one being so weak. So that's that's something to keep in mind. This this basal wound on this tree. Basal just means the bottom of the tree, was probably caused by weed whacker damage when it was young, or maybe a car hit it. And the problem with that is that, that wound was never able to be sealed over and might have been too large and has just basically continued to grow over time and is mostly the tree's most likely hollow, moving up into that first log there. And like I said, can be functionally alive but not very safe in an urban environment. It's not structurally sound. So remember, the important fact is that any wound you make stays with the tree its entire life. So we're trying to minimize that damage.
Moving on with that idea of compartmentalization of decay and trees are coded and we just talked about, we are going to be making cuts in a very strategic manner. When we're talking about removal cuts, which is taking a branch off of the tree, where it meets the stem of the tree or the trunk of the tree, here making cuts right outside with what's called the branch collar. And the branch collar is a swollen area of tissue that marks the intersection of stem and branch tissues that have been overlapping every year with layers of wood to create an extremely strong bond, kinda like a Chinese finger trap, or like a laminate. So this is an extremely strong branch attachment. And where those two with a branch in the stem meet, they create the swollen area, and behind it is was what called the branch protection zone. Now the branch protection zone has chemical and physical properties that slow or stop the spread of decay into the trunk or into a parent branch. So this branch protection zone is also present in any kind of branch junction or branch union, but it is most prevalent where branch meets the stem of the tree. So it's preventing any kind of decay from moving into the actual the the trunk of the tree into the main part.
So if you make your cut outside of this nice branch collar, this swollen area, literally like the collar of a shirt, and you leave the branch bark ridge intact, which I will show you in a moment. Along this dotted line, you should get a nice donut, nice even donut of wound wood starts to appear and eventually it will seal up and completely seal off that wound. And if cuts are made young enough on young trees, you sometimes you can't even tell any kind of pruning cut has been made. Now if you cut too far into the branch collar, you're going to end up with a larger wound. And it could be funny shape. And also the wound would since you've compromised that bbz, that wound would might not form evenly. And you might get this oblong and kind of warped wound wood and it may not be able to steal all the way. You also get a stress response in the tree, you will see sprouts probably come from around this kind of wound might be too large.
Here is a cross section of showing the branch union to a stem or parent branch. And you can see that swollen area right here. Kind of where it's tapering off into the branch area. And you see that dark V is the branch protection zone. It's literally you can see it inside in a cross section. So your cut would be along this red line on this yes line. Outside of that the no is a flush cut, you're literally lopping off that branch protection zone, not very good. And you can see where the branch originated. And those overlapping annual layers of wood between the stem and branch that create that beautiful branch attachment. Down here you can see where the branch protection zone was left intact, and this wound has completely sealed over. So it's just amazing how trees are able to do this out in nature.
So here's an example of a nice branch collar on young maple as kind of this wrinkly area, this swollen area and make your cut right about here. Branch bark ridge is basically just the bark from the branch and the stem or parent branch again, any branch union and the bark crashes into each other like tectonic plates, if you will, that create that push against each other and create mountains This is literally a ridge like the ridge on a mountain. So if you see that that's a good sign of good strong branch attachment.
So flush cuts, I touched on that briefly with that last cross section. You can see here that a flush cut creates a much larger wound. You don't see that branch protection zone, it has been completely lopped off, you're seeing a lot more decay. Like I said, the larger wounds, there's more surface area for decay to set into. So decay is permitted entrance into stem tissue, I mean it has a direct route. And also like I said, you're gonna get a stress response from the tree, it's gonna send out sprouts from dormant buds within the bark. Wrapper cut you'll see that branch zone is nice intact, they can even see the wound wood starting to, to develop there. Wound paint does not help. So some people think that by painting a wound, it helps it to sealed off and promote wound... wound closure, but it does not do anything to prevent decay or disease. Studies have shown, except in the case of pruning oaks, which we mentioned earlier, we don't want to engage in that during the growing season anyway. But if you absolutely have to do pruning on any oaks during the growing season, you can use wound paint to seal up the wound so that they don't weep. And so that they don't track those sap feeding beetles that can spread oak wilt. That's the only case in which you want to use this kind of wound paint. It's actually petroleum based a lot of times, and so it'll end up doing quite the opposite, it'll seal up the wound and hold moisture against it. And it just creates an environment for decay and, and pathogens to take hold.
So stumps are not good either. Stubs are kind of, they also bypass the bridge protection zone. So by leaving a stub, we're allowing deadwood to exist, where decay could sudden, and then if it does, then it has a direct route, straight through that branch protection zone. The branch protection zones not able to start building that wound wood. That wound wood was actually impeded by the leftover stub, as you can see here. Now nature, if you're walking in the woods, you'll see trees that naturally shed branches if a branch dies, you'll see a die back to that branch collar. And you'll see that wound wood try to you know, develop. And that's fine out in nature, that's just, that's just dandy. You know, if the tree falls, it's less likely to hurt somebody than it would be in an urban environment or in your backyard. So that doesn't, it's not as imperative that the wound completely close out in nature. Now in our manmade environments, we definitely want that wound closure to occur. Because I guess that, that branch protection zone is being bypassed by that stub, that decay is being able to get into the parent branch or the stem, and it's marching its way through that wall one, that weakest wall of code it.
So up till now we've been talking about removing branches from the tree itself up to the stem. Sometimes we don't need to remove the entire branch, sometimes we can do what's called a reduction cut. Again, I show this graphic because this is not a good example of a reduction cut. If that stub were cut off to that side branch, it'd be a lot better. Same here.
When we cut, when we do a reduction cut back to a parent branch, we want to cut back to a branch that is at least one third the size of the parent branch or the branch that's being removed. And that way, there's a big enough branch protection zone there to help seal off that wound. So you still see on these branch unions further up in the on the branch or in the tree, you'll still see these branch bark ridges. And that's indicative again, of good branch attachment and a good branch protection zone beneath. So we that also that branch bark ridge gives us a little guide as to where to make our cut, we typically want to make the cut perpendicular to the angle of the branch. And that makes for the smallest one possible, the more you know, not not oblong, not angling it so that water can sit on it that kind of thing. This, this is cut in such a way that water will slide off of it and not sit on that wound and allow that, that wood to rot. Also you're not cutting into that branch protection zone and you're not cutting into any of that tissue that's going to be left behind. This branch is going to take over as the terminal branch when you're removing this guy.
So when we're doing these reduction cuts, we're cutting back at a node. This is called a node and again, in horticulture in general, Aa node indicates where parts of a branch, parts of plants join and that's typically used for the idea of propagation. You can cut back and root, like an herbaceous plant this way. So we're not talking about topping. Topping is not utilizing production cuts, tapping is rounding over of typically a mature tree that's gotten too large for where it's at. And in an effort to make it shorter, people will hire somebody who will just cut indiscriminately and round over a tree's crown. And these, as you can see our inter noodle cuts, they're not being cut back to any side branch, especially not any side branch that is big enough to seal up any wounds. So there's multiple wounds occurring on this tree, death by 1000 paper cuts, quite a few wounds to allow decay to set in, and then each one will most likely get a column of decay down that wall one in each one of these leftover branches. And also, topping is terrible, because while it looks bad, it is removing a really remarkable amount of foliage from the tree, sometimes the entire crown most of the times most of the entire crown.
And so the tree will respond with a stress response, of course, with these water sprouts or these epicormic sprouts. And these are just like I said, those dormant buds that are within the bark, that take over when the tree realizes 'Whoa, hey, I have no more foliage left, I need to grow back my foliage. And I need to be able to feed myself.' So these little branches shoot out at a super fast pace, and they end up being taller than the original tree that was reduced. So topping is actually not a good idea for that reason as well. These little, little epicormic branches end up growing so fast, that they don't have that nice interlocking layers of wood with the parent branch year after year, that creates that nice branch attachment that I've been talking about. So these guys get so big, and they're basically hanging on by a thread. And they will tend to have, they will have a tendency to shear off in the wind in any kind of ice or snow load. It's just they're, they're a hazard, is a very big problem topping of trees. So please don't do it. And please select tree care companies that don't engage in it as well.
So when removing larger branches, and you'll encounter this, I would call a larger branch anything more than an inch in diameter. We want to avoid this banana peel effect when the branch, when you're cutting from the top of a branch through that, that wood on the bottom is going to want to give way and it can peel all the way back to the tissue that we want to leave behind on the stem or parent branch. We don't want that to happen, right. So what we're going to do is remove weight of the branch. And we're also going to do an undercut that severs that bark, so that when the branch does snap off, we're not peeling that bark. So we do an undercut first, about one third to one half of the way through a branch come out a little ways, maybe about an inch and cut directly through from the top and that removes most of the branch. And then we're left behind with the stub and at that point, you have a manageable piece that you can cut through to make the removal cut or reduction cut. Now if you're dealing with a pretty long branch, or one that is a little top heavy that has a lot of foliage on it, you maybe want to do a couple of these cuts. And this also prevents your saw blade from getting pinched or having this rip off and having a big split during mess to cut the rest of the way through. So all we're doing with that undercut is severing that continuous bark and creating this nice little hinge that just lets the branch to snap right off cleanly.
Moving on to pruning tools so I talked about the saw just now doing that three part cut. The tools that we would be using in an outside demonstration, if you're going to join me for one of those that'd be great, are going to be pole saws, which are basically just like a handsaw but on a long pole, and a pole pruner, which has a bypass pruner mechanism which I'll talk about in a moment. Hand saws, which are fabulous, a lot of them are are foldable, they collapse upon themselves to protect the saw blade and you. Some have sheets, I prefer the foldable and hand pruners for smaller branches and loppers for slightly larger branches. So and I'm not going to mention that, well, I will, this chainsaw, we're not going to be using chainsaws for any of the pruning that I'm going to be teaching you about. Because if you're busting out a chainsaw, either you're cutting up firewood or doing small tree removal. We don't use chainsaws in your typical pruning. It's just if you're removing tree branches that big, more than likely, you're dealing with a mature tree and I don't recommend that and I'll talk about that in a little bit, a little while.
So here we have the bypass hand pruners. Now bypass pruners have this nice scissor action. They have two movable handles that create like a scissor cut, as opposed to a anvil type of traditional pruner that has a stationary chopping block in blade that kind of pruner that anvil pruner, has more of a tendency to crush or tear tissue. While this bypass pruner, a scissor like pruner makes a cleaner cut and it's more accurate as well. So up to about a half inch. Some of them are graded to be used up to three quarters of an inch, but at some point hand strength plays in and if you find yourself twisting your hand pruners to get a better cut or get through part of the cut, then most likely you need to move on to loppers, and get a little bit more leverage. So I recommend hand pruners up to only a half inch, half inch up to an inch, you can use loppers, if you're pretty strong, they give you a little bit more leverage and have that same bypass pruner mechanism, or you can use a handsaw and a lot of these are equipped so that they have alternating teeth that allow you to cut in both directions. And so if you get a good one, good one for your money, the it'll cut through things like butter, you won't have to put too much effort into them. I personally like the silky pocket boy, which is what I use in my pruning demonstrations. It's a little higher end but..
So when we're working with any kind of tool, as a homeowner, or even a professional, you know that working with sharp cleaning tools is best, makes our job easier, protects the health of our trees, even protects our health, because you know, it can be bacteria on these on these tools that could get into a little paper cut, you never know. Um, we want to sanitize and sharpen tools as needed. A lot of times your pruners are best just replacing the blade altogether. They're pretty cheap. Same thing with hand saws, you can just buy a replacement blade instead of spending the time sharpening each individual tooth on a saw. What I suggest for sanitizing out in the field is we want to sanitize between trees of different species of course, or even the same species or even between cuts on the same tree as in the case of black knot on trees in the family rosacea like your peaches and your cherries, you don't want to spread that pathogen to healthier parts of the tree. So sometimes it's necessary to make the spray and sanitizer tools between cuts on the same tree. So what I use out in the field is 70 to 100% isopropanol alcohol or ethanol. I used actually denatured alcohol from Lowe's and a chemically resistant sprayer and I just put a dash of water in there. It's nice because you can just spray it directly onto your tools out in the field and it dries on its own. You can let it dry or you can wipe it off and reapply and it's the least corrosive method of cleaning your tools especially out in the field.
Something that's a little bit better for sanitizing and maybe you can do it occasionally like once a week depending on how often you're pruning or how bad your tools are. You can soak your tools in bleach or try some, try sodium phosphates solution for bleach it's two cups bleach to one gallon of water for 30 minutes soak in for trisodium phosphate which is basically deck or siding cleaning cleaner. Um you do one cup tsp to nine cups of warm water for three minutes. So, so these are extremely effective at sanitizing tools, but they're a lot more corrosive to metal tools so use sparingly. You can also use one cup pine oil to two three cups water and that's a 10 to 15 minutes soak and that's a little bit less corrosive to your tools. We could also just use dish detergent. I used that for your general cleaning, that it's good at cutting through grease and stickiness. Could also use a wire brush if you happen to get a really bad sticky stuff on there, or any kind of rust to clean that off, I use steel wool and you can buy that at Lowe's as well. You're gone for a new super sticky messes. And of course finish up with the WD 40. So that you have clean, functioning tools.
Pruning safety, this is pretty straightforward slide. I recommend basic PPE, which is gloves and eye protection. And that is because I have definitely almost poked my eyeball out, while trimming a tree especially like your conifers when you're removing deadwood from the inner canopy like your spruces, they have a lot of little tiny branchlets that kind of shoot off in every direction and your, you are bound to poke an eye at some point. So glasses or eye protection is good. And gloves are extremely important, they help you with grip. They keep your hands a little warm if it's chilly out. And I've definitely pinched my hands with bypass pruners so they help with that too.
Never ever, ever, please do it for me, never prune near power lines. Um, if you feel the need to prune a tree near a power line, the tree is most likely in the wrong spot to begin with. And you can call your local power company to do the work for you or hire a responsible and licensed and bonded arborist to do the work for you if AEP or mon power won't do it. Um, and I say this, even if a tree is near a power line if trees conductive water, and we as human beings are 70% water so if you are holding a branch that is green, a green branch or even a dry branch, if it touches a live power line, you could be electrocuted. So just don't mess around with that. Plus you're working with metal tools to boot. So also, if you can't reach the job from the ground with a pole pruner or pole saw, please don't break out a ladder, it's just not a good idea. Your center of gravity is completely thrown off and especially with reaching to to do any kind of pruning cuts is just is not a good idea, you most likely need to hire an arborist.
So now, I am moving on to young tree training, I'm going to specifically talk about that, like I said, because we want to work with these young, vigorous, small trees, make small cuts before they become a big problem later on. So you want to create good structure and so that that structure sticks with the tree as it gets older, is better able to withstand wind, ice and snow loads. And it's just overall more healthy and happy and beautiful. So just like a large breed puppy, a lot of people will buy a tree not knowing what its mature size might be and planted it in the wrong place. And maybe it has terrible structure. And it ends up being a big problem like a large breed puppy and you're like oh my god, goodness, I didn't realize this is going to be a 200 pound dog. So okay, so if you just newly planted a tree, you might want to give it at least two years in the ground one to two years in the ground to develop a good root system. You don't want to go immediately pruning on it, it's not going to go crazy within one to two years you could wait. So here on the left hand side we have a young ash tree which has terrible structure, it looks like right here it was lopped off the leader was lopped off and then all of these little branches on the side are now competing to be king. We don't have a visible leader here. It's all just a mess. You have branches coming from the same place on the stem, poor branch attachment this this thing could be split like a banana when it gets older, like this tree that just zoomed in prematurely on the right, or this tree that split completely apart. Or this tree in your front yard. So we have enough to worry about these days. We don't need trees falling apart in our front yard. So let's do the work while they're young. Before we have to hire a professional.
So when we're talking about structure of a tree, there are two different growth habits of trees. One is your excurrent or pyramidal shape and structurally, this is the strongest structure that a tree can have and has, not in this case on the... imagine this has one leader. So you have one leader, and you have scaffold branches nicely spaced and with good branch attachment going all the length, the length of the tree, um, this is the shape that your conifers typically have that pyramidial shape and conifers are built to shed snow and ice, because you know, they're typically northern. Your spruce and your firs tend to be more northern, and they are able to shed that, that snow and ice because they're are built in that conical manner.
So many species of trees have this what's called strong apical dominance, which basically just means the top bud growing fastest when they're young and that is because they are trying to reach the sun as quickly as they can. So they have this excurrent crown shape when young, and some species like sweet gum and yellow poplar will maintain the structure into maturity. But a lot like your oaks and maples naturally develop an open or rounded crown as they age, this is known as a decurrent structure, you don't have to remember these terms and just know that certain species have more of a pure metal structure, and others have this rounded structure. And as you can see, in this oak, there are many, many large branches all coming from a similar space on the trunk, you can't see one single leader, um, it's, you know, it's a beautiful form. But you still want to maintain that, that pure middle form as much as you can, so that the tree is structurally sound, this guy could, in theory, shed these larger branches, because they most likely are all originating in the same area and don't have great branch attachment. And we'll talk about why that is here in a little while.
So when we're training on trees, we want one central leader as much as humanly possible, we're still shooting for that central leader trying to go up into the top most part of the canopy, even if it's not as blatantly obvious as an x current species. So there can only be one leader, as in the case of Highlander, I hope somebody gets that reference out there.
So moving along with tree training, here we have a young sapling with a nice central leader, we want to next select a lowest permanent branch, this is going to be the branch where your clearance is; this branch is going to be one of your lowest or the lowest scaffold branch, a big branch. You can leave smaller temporary branches, because they won't have a tendency, they're going to be out competed, they're just going to be there to give the young tree extra food so that it develops good stem taper and it's nice and vigorous. And then you can remove those temporary branches later on if need be. So if there's any little guys underneath this lowest permanent branch, when the tree is pretty young, you can remove those later, it's not going to harm anything, they're not going to get big, but your lowest permanent branch will be. So keep in mind where this your tree is planted. If you need clearance for say, a sidewalk, or a sign or something like that, you might want to make your lowest permanent branch something a little bit higher. So and also, you don't want to like I said remove all branches up to that lowest permanent branch, you want to slowly do this training over a few years as necessary. Hopefully, if you've selected good nursery stock, you won't have to do much at all, we want to maintain this live crown ratio of at least 60% live crown for the total tree height.
Next, we're going to select our permanent scaffold branches. So we select the lower, the lowest most point branch. Now we're looking at branch spacing, so when you're looking at the tree from the side, you want to make sure that your branch spacing is nice and even, if possible, as much as humanly possible. With any tree that you anticipate to be larger than 30 feet tall at maturity, you maybe want to keep a spacing of 12 to 18 inches between these scaffold branches. Like I said, if you have little ones in between those temporary branches, they're not going to be a problem unless they're rubbing against something but your larger branches you want to keep space 12 to 18 inches. If the tree is going to be less than 30 feet tall, like a dog wood or red bud, you can keep those scaffold branches six to eight inches apart, it's not, it's not as big a deal there. You basically just creating a nice even canopy and allowing each of those branches to get the light that they need to feed their, their foliage.
And then we have to think about the tree radially. So if you were to look at the tree, from the top, is the canopy lopsided? You want to make sure that you don't have too many branches on one side and not the other. And you can correct this with a little bit of pruning over time. If there's too many branches on one side, you can maybe reduce one or two of them and encourage any branches on the other side to be reallocated some resources to grow bigger. And, as you will see, and practice out in the field, pruning is both a science and an art. So we are equipped with the knowledge, the science behind why we do what we do. But it's also kind of like a feeling you have and it comes from practice working on trees, where you're going to know what kind of cuts to make, and you're gonna know what kind of balance that you need to strike between growing seasons. So it's kind of you feel your way, and you're gonna get better, especially after you get some experience in the field with me or one of my partners.
So when we're looking for these scaffold branches, we want to make sure we have that good branch attachment. And I mentioned before that a branch bark ridge that sticks up like a ridge is a good indication of good branch attachment. Also, you want the, the angle between the branch in the stems to have this nice U shape, you don't want it to be too acute of an angle, you don't want it to be V shaped that, that has a tendency to develop codominant branching. So you also want that branch to be less than one half, or even one third the diameter of the stem or the parent branch that it's attached to. And that is because structurally, you want that, that stem to be able to hold on to that branch, you and also the branch is too large and might not be able to, it may become a codominant branch situation, like I said, I'll talk about that in just a moment. And the weight of that branch may be too much for that branch attachment. So make sure that those branches are at least half the size of the of the stem. Here is a cross section of that beautiful, interlocking, overlapping layers of annual wood between the branch and the stem that looks like like a Chinese finger shop, if you will, like it's both flexible and strong.
And the attachment is so critical to the structure and function of a tree and I can't stress it enough. Here we have poor branch attachment. So you can see, in the book, these cases, these branches are the same size, we don't have that branch that's less than half the diameter of the parent, or stem. And you also don't see that branch bark ridge. In fact, it's inverted, it's actually growing in on itself, that's called included bark. And when included bark will do is instead of interlocking layers of annual wood between these two branches, you'll actually have them growing against each other and forcing each other apart over time. It is a terrible, terrible situation and you can also see a bad branch attachment by the angles, that V shape there.
So three things to look for in a bad branch attachment, the V shape, or acute angle of attachment, the included bark, and the size. There's no difference in size. So you know that might be cute on a small breed puppy, but as they get older, it'll be a huge problem. If you've ever had to deal with a Bradford pear, you'll know that this is a serious problem. Those guys tend to split apart like a banana. So they'll get a nasty storm coming through or a hard freeze, might get a frost crack and bam, half the tree splits and falls off. Not a, not a good situation. This one is in the backyard of someone's home with children. You know, I wouldn't let my children play around that tree, who knows when it's going to go.
So hopefully you won't have to do too much work on your young trees. We're going to be trying to space out this work over two to five years. Because we don't want to remove too much live canopy in any one growing season. We don't want to make too many wounds, we want to give the tree a chance to seal up any wounds that we create. Also, like I said, if you are selecting the right nursery stock, you shouldn't have to do too much corrective pruning on it and I will cover that in another lesson. So we want to, the trees in the ground, we want to wait one to two years, probably two depending how on how vigorous the nursery stock was, how good its root system was all those things that we take into mind. And we want to never remove more than 25% of the live crown in any one growing season. And like I said, that's because you're trying not to starve the tree, we're not trying not to instigate that stress response, we're trying to give it a chance to seal up those wounds and catch up. Um, so it's just like, you wouldn't go and get like five surgeries in a row, you'd want to heal from at least one or two minor surgeries before getting more surgery, that kind of thing. Um, and in the case of mature trees, we don't want to remove more than like 10% live crown in any one growing season, if any.
So like I said, those temporary branches, they provide the tree with more food, because it's a young, a young sprite and kids tend to eat buckets, sometimes when they're having a growth spurt. And your temporary branch is also encouraged good stump taper, you want the tree to have a nice taper from a wider flared root collar up to a nice, graceful leader, top of the leader. If you remove too many branches, it may becomes a little bit stunted and not have that good stem taper. And that's just again, lends to poor structure.
So here's some examples of pruning young trees. So here we have our nursery grown tree. Sometimes they'll stop them from becoming too large in the nursery or in the, in the growing rows. We have leaders A, B and C competing there and then a couple of side branches one and two, that could also become a problem as time goes on. So in this case is correct pruning we have removed A and C and allowed B to become the main leader and one and two have become our scaffold branches. And as you can see, as time goes on, it develops a nice, evenly spaced crown. That's not considering radially, you know, drawing skills might not be exactly on par here, but incorrect pruning, you can definitely see a difference. The lower branches have been removed, those scaffold branches are just not there. Instead, the three leaders are left, they are attached at the same point on the on the stem and as you can see, over time, they become crowded and have terrible branch attachment. And that tree will most, more than likely split at that branch union.
Here's another example. We have leaders A B and C competing, you can kind of see that central leader that wants to be king here, but we need to give it a little bit of help reallocate some resources. So this is after light pruning, we've reduced a couple of branches back to a side branch. And that is allowing some of those resources to go to that main leader. And if you were going to do a little harder pruning, which I would not suggest, but this is a little bit more removal, and you're getting to see that pure metal shape a lot more, as if you were going to lead these guys.
So once again, you know there's a lot of conditions and parameters to consider. Whether the tree is stressed, can it handle more pruning? What species is it? Is it a good compartmentalizer? Will it be able to seal those wounds quickly? Is it in a good location? Is it going to get the resources that it needs to seal up those wounds? All of these things we have to take into mind. And that just comes with experience quite honestly, I'm still learning pruning after all these years.
Another example, we have a lot of temporary branches on this little seedling, there's going to be a few left. But our main scaffold branch looks to be this guy or the lowest permanent branch. As you'll see as it grows, that branch is staying at the same level. And after time, I'm removing those temporary branches because the tree doesn't necessarily need them anymore. They might get in the way of you going around that tree or something and you're seeing that you get that nice pyramidial shape over time. It could be a species that just naturally has that too. And we were lucky in that I had a nice central leader there.
Moving on to mature trees. So mature trees like mature humans may not be as vigorous as in their youth, so we want to minimize any kind of wounding that we do to them. Also, larger limbs mean larger wounds to seal up. Also, your larger trees may require the employment of an arborist with the appropriate equipment to get up into the canopy or use a chainsaw. So some techniques that we might use on mature trees include crown cleaning, and that's just like your three D's, your dead, damaged or diseased branches. Pruning out sprouts, branches that are crossing and rubbing, weak branches, and reallocating resources to the better branches and improving that structure. Crown thinning, I'm going to bring back up the Bradford pear again, they have a tendency to have a very thick crowns that cast a lot of shade, it's hard to grow anything underneath of them, your little leaf lindens are the same very, very dense crown. In some cases, you may need to thin out the crown. And this can be done by an arborist who is able to climb up in the tree. And what you're doing is removing smaller branches, inner branches in the crown in an even manner to allow for light and air penetration. So once again, reallocating resources to other left behind branches.
Crown raising, if you're stuck with a tree that is mature and maybe is in the way of a sign you're going to put up, you do a little raising or something hanging over a sidewalk poking pedestrians in the eye, you know, you need to do a crown raise. And again, if you can reduce, instead of remove an entire branch, that'd be great, so that you don't stress the tree too badly. And if you need to do ridiculous crowd raising, maybe try to do it over a couple of growing seasons. Um, you know, reduce and then remove the next growing season, that kind of thing. Or maybe relocate the sign or replant a different type of tree further away.
Reduction, we're using those reduction cuts that we talked about earlier, where we're cutting back to a node. This is not topping so we're cutting back to those little side branches that are at least one third the size, or one third the diameter of the branch being removed. Pruning mature trees, continuing with this, we don't want to, this is an example of poor practice and crown thinning so too much inner foliage and small branches have been removed on the inside of the canopy leading to a lot of foliage left on the ends of the branches, which is called Mayan tailing. It's severely hinders photosynthesis because you're removing a lot of light foliage, and also places heavier loads on the ends of the branches and it makes them kind of tip heavy. And in the case of this tree with this poor branch attachment, you're basically you know, you're you're setting it up for splitting apart. So you want to maintain that even crown distribution and try not to stress the tree. Again, never pruning more than 25% of the live crown in any one year. In the case of mature trees, please keep it to less than 10% if you can and hire an arborist because in the case of mature trees, sometimes they're just too big and we don't want to break out a ladder.
Um, some things to keep in mind when you're hiring an arborist um, see if they have any professional affiliations. Are they a member of the International Society of Arboriculture? Are they a certified forester? That kind of thing. This kind of ensures that they are a professional and that they have a higher standard of work and quality of work. Maybe see if their ISA certified, you might pay a little bit more but if they are pruning a mature tree on your property, you want to make sure it's done right and that your tree is not stressed out. Obviously proof of insurance is very basic, list of references if they are repeatable. Arborists they have, will have no issue with providing you with a list of references and feel free to call them, don't be shy. And try to avoid any tree company that advertises topping as a service or uses their workers use tree climbing spikes to climb trees that they're going to be pruning. Now if they're going to be removing trees on your property, no big deal these climbing spikes that trees coming out anyway. But you don't want to climb a mature tree that you intend to keep and allow them to use climbing spikes. You're basically just stabbing the tree all over. It's just not it's not good. A lot of low wounds for for decay and other pathogens to get in.
Here are some further reading and resources that are available from the International Society of Arboriculture. thetreesaregood.org. And also the Arbor Day Foundation is a good group to go with. Whenever you're consulting about pruning trees, try to stick with a reputable source like an extension or University Extension, or like I said, ISA or Arbor Day Foundation. And these links will be available on our wvsuextensionservice.com website, as well as this recording for, for future reference.
And again, my name is Liz Moss, I'm Extension Agent of Urban Forestry. And I have a degree in forestry. Feel free to contact me anytime with questions, concerns. Or if you want to set up a pruning demonstration or workshop. We have some videos demonstrating pruning techniques. I'm going to probably come up with some of those in the future as well. And then again, this is our main hub here, the wvsuextensionservice.com make sure that you visit it regularly and see what kinds of events that we have and see what courses are available to you. And I thank you for your attention and this course. And yeah, happy pruning.
