Roger: 0:02

Talking Trees with Lillian Jad. Welcome to this episode of Talking Trees. Today, we'll focus on the ways trees respond to stress. Our first source dives into the physiological and morphological changes trees undergo, including the development of secondary growth like epicormic shoots. The second source challenges the common arboricultural practice of removing these shoots, emphasizing their role as essential adaptive mechanisms that support tree survival and regeneration. Let's explore these critical insights together.

Jad: 0:40

Hey everyone and welcome back for another deep dive. You know, as arborists we come across epicormic shoots all the time in our work.

Lilly: 0:49

Yeah, they're everywhere.

Jad: 0:50

They are, but today we're going to go deeper than just whether to prune them or not.

Lilly: 0:54

Yeah.

Jad: 0:54

We've got a ton of research and observations here and we're going to really unpack why they form in the first place.

Lilly: 1:01

Right.

Jad: 1:02

The different types and really what those epicormic shoots tell us about the health of the tree. So let's start with the basics for anyone who may be tuning in. Okay, who's not as familiar. What exactly are epicormic shoots? Where do they even come from?

Lilly: 1:16

So think about it this way Every tree has this hidden potential just beneath its bark. They're just waiting for the right moment to kind of show themselves. These dormant buds are like backup generators, lying in wait until the tree needs them, and then, when stress hits, the buds can activate, they push out this new growth, and that's what we call epicormic shoots.

Jad: 1:40

So it's not just random new growth. Oh, it's a specific response triggered by stress.

Lilly: 1:46

Exactly.

Jad: 1:47

But trees can't exactly run away from trouble. They can't. So what kinds of stresses are we talking about here that would trigger these?

Lilly: 1:53

That's the thing about being rooted in one place is that trees have to be incredibly adaptable.

Jad: 1:59

Yeah.

Lilly: 2:00

So imagine a tree. You know it's along a street that suddenly gets paved.

Jad: 2:04

Oh yeah.

Lilly: 2:04

So now it's dealing with heat radiating off that asphalt, possibly some root disturbance from the construction Right, who knows what else change in its environment, and that's you know, that's definitely a recipe for stress.

Jad: 2:16

It's like the tree's world just got flipped upside down.

Lilly: 2:19

Yeah.

Jad: 2:19

And it's trying to adjust. So walk us through like how that stress response actually plays out.

Lilly: 2:24

Well, researchers have broken this down into like four phases.

Jad: 2:27

OK.

Lilly: 2:27

So first comes the reaction. You know, the tree's normal processes get disrupted, kind of like that initial shock.

Jad: 2:34

When something really unexpected happens. And then there's recovery, where the tree is trying to compensate Okay, maybe by shifting resources around or slowing its growth a little.

Lilly: 2:45

So it's trying to get back to normal.

Jad: 2:47

Exactly.

Lilly: 2:47

But what if that's not enough?

Jad: 2:48

Right. So if the stress continues or gets worse, you move into the damage phase. Okay, and this is where you start seeing some you know, irreversible harm, maybe some dieback in the branches or just reduced growth overall. But here's the thing If the stressor goes away or if the tree manages to adapt, then we get to the regeneration phase, and that's where epicormic shoots take center stage.

Lilly: 3:14

Oh, wow. So it's like the tree saying all right, I've weathered this storm, time to rebuild.

Jad: 3:18

Yeah, exactly.

Lilly: 3:19

And those shoots are like the construction crew, but I've noticed they don't always look the same.

Jad: 3:24

Right.

Lilly: 3:25

Sometimes they're upright, sometimes they're more like branches. Is there like a system to that?

Jad: 3:29

Absolutely so, the type of epicormic growth you see.

Lilly: 3:33

It's like reading the tree's strategy how is it dealing with this particular situation? And so we broadly categorize them into three different orientations. We have orthotropic, plagiotropic and agiotropic.

Jad: 3:45

Okay.

Lilly: 3:46

And each one tells a different story about what that tree is trying to achieve.

Jad: 3:50

Okay, this is where it gets really interesting For us arborists. Right, we're out in the field.

Lilly: 3:55

Right.

Jad: 3:56

I'm looking at a tree. I see these shoots. How do I know what that means for the overall health of this tree?

Lilly: 4:02

So let's say you see lots of orthotropic shoots. So those are the ones that are growing straight up, vigorous, almost like miniature trunks. That's a sign of resilience. The tree is aiming to restore its crown, it's reaching for light.

Jad: 4:15

So it's almost like the tree's trying to rewind the clock.

Lilly: 4:17

Yeah.

Jad: 4:18

Go back to how it was before the stress hit.

Lilly: 4:20

You got it Now. Contrast that with plagiotropic shoots.

Jad: 4:24

Okay.

Lilly: 4:24

These are the ones that grow more horizontally, like branches, and often indicate a different strategy.

Jad: 4:30

Okay.

Lilly: 4:30

It's called retrenchment, and this isn't necessarily a bad thing.

Jad: 4:34

Okay.

Lilly: 4:34

It just means that the tree's being a bit more conservative, may be sacrificing part of its crown to conserve energy and resources.

Jad: 4:43

So less about full restoration and more about strategic downsizing to survive.

Lilly: 4:48

Exactly. It's like the tree saying OK, things are tough, I'm going to hunker down and focus on what I can sustain. And then you have those a geotropic shoots. So those the short, stubby ones that are growing every which way. Those are a little less common and they can indicate more severe stress or even decline.

Jad: 5:07

So just from looking at the type of shoot we can get some clues about how the tree is coping. That's really helpful Even before we start thinking about pruning choices or other interventions.

Lilly: 5:17

It really is all about understanding the language of the tree, and there's more to the story than just their orientation. You know, we also need to think about how those shoots actually function and what they mean for the tree's energy budget.

Jad: 5:31

Yeah, and here's where we debunk some myths.

Lilly: 5:34

Yeah.

Jad: 5:34

Because I know a lot of people, even some arborists.

Lilly: 5:37

Right.

Jad: 5:38

See, epicormic shoots, as you know, like a problem Right Like oh, those are suckers, get rid of them. Yeah, those need to be removed.

Lilly: 5:45

That sucker label. You know, it's so misleading and it often leads to unnecessary pruning. Yeah, epicormic shoots aren't parasites, right, they are the tree. Yeah, it's just new growth coming from those dormant bugs.

Jad: 5:59

So they're not stealing resources from the rest of the tree.

Lilly: 6:02

Not in the long run. Initially, yes, they're drawing on the stored energy reserves. Ok, kind of like a savings account.

Jad: 6:09

OK.

Lilly: 6:09

But very quickly they become self-sufficient and produce their own energy.

Jad: 6:14

Oh, wow.

Lilly: 6:14

Through photosynthesis, just like any other branch.

Jad: 6:17

So it's not like a constant drain, right, it's more like a short-term investment for the tree, exactly, but knowing how to explain that to a client who's convinced you know those suckers are ruining my tree, get them out of there yeah, that's a skill in itself.

Lilly: 6:34

It really does require a shift in perspective. You know, instead of seeing them as the enemy, we need to understand what those shoots are trying to tell us.

Jad: 6:42

Exactly.

Lilly: 6:42

Are they a sign of a bigger issue that we need to address, yeah or are they simply the tree's way of trying to adapt and bounce back?

Jad: 6:50

That's a great point, instead of just reacting.

Lilly: 6:53

Yeah.

Jad: 6:54

And reaching for the pruners.

Lilly: 6:56

Gotta get those suckers.

Jad: 6:57

We need to take a step back and say, okay, tree, what are you trying to tell me here?

Lilly: 7:02

Exactly, and sometimes the answer is just let me do my thing.

Jad: 7:05

Leave me alone.

Lilly: 7:06

Remember, trees have been evolving these survival mechanisms for millions of years.

Jad: 7:10

Yeah.

Lilly: 7:11

They're pretty good at figuring things out.

Jad: 7:12

They know what they're doing.

Lilly: 7:13

They do. Yeah, they really do.

Jad: 7:15

So let's get into the practical side of things.

Lilly: 7:17

Okay.

Jad: 7:18

How does all this knowledge about epicormic shoots change the way we actually approach tree care?

Lilly: 7:24

Well, for starters, it really highlights the importance of using proper pruning techniques.

Jad: 7:29

Okay.

Lilly: 7:30

We've all seen examples of bad pruning, you know, like lion tailing.

Jad: 7:35

Oh yeah, I cringe every time I see that.

Lilly: 7:37

Yeah, where you just strip away all those inner branches.

Jad: 7:40

Yeah.

Lilly: 7:40

And leave this tuft of foliage at the end.

Jad: 7:43

It looks so unnatural.

Lilly: 7:44

It does, and now we understand why it's so harmful.

Jad: 7:48

Yeah.

Lilly: 7:48

You know it disrupts that tree's natural balance, weakens the structure.

Jad: 7:52

Right. And it also removes a huge chunk of the tree's photosynthetic capacity. Oh yeah, those inner branches yeah, those are crucial for energy production.

Lilly: 8:01

Exactly.

Jad: 8:01

So it's like we're cutting off the tree's food source.

Lilly: 8:04

Yeah.

Jad: 8:05

And then we're surprised when it freaks out and sends out a ton of epicormic shoots to try and compensate.

Lilly: 8:11

Right and they're desperate to regain that balance. But those new shoots, although you know well-intentioned they can create these weak attachments.

Jad: 8:20

Right.

Lilly: 8:21

And further compromise the tree's structure.

Jad: 8:23

Yeah.

Lilly: 8:24

And so it's just this vicious cycle.

Jad: 8:26

That's the alternative. What if a client wants their tree pruned for, like, aesthetic reasons or to improve clearance? Yeah, how can we do that in a way that respects the tree's biology and avoids triggering that whole epicormic frenzy?

Lilly: 8:44

It all boils down to selective pruning. We need to be really strategic, only removing the branches that are absolutely necessary, while preserving the tree's natural form, that natural balance. Think of it as like a gentle nudge, not a major overhaul.

Jad: 9:00

So no more hacking away at the interior. Definitely not Leaving it looking like a lollipop.

Lilly: 9:04

Nope, we need to be mindful of those energy reserves and avoid removing too much foliage all at once. Okay, and remember, sometimes the best approach is just to leave the tree alone.

Jad: 9:14

I love that. Leave the tree alone Sometimes that's the best tree care we can provide.

Lilly: 9:18

It can be.

Jad: 9:19

But even beyond pruning, understanding epicormic shoots can help us diagnose other issues. Right Right Like, let's say, I see this sudden burst of shoots on a mature tree that's never had them before.

Lilly: 9:30

Yeah, that's a red flag, isn't it? It's a sign that something has changed in the tree's environment.

Jad: 9:35

OK.

Lilly: 9:36

Or that it's experiencing some kind of stress that we need to investigate further.

Jad: 9:39

OK, so what kind of things would we look for?

Lilly: 9:42

It could be root damage, soil compaction, changes in water availability, nearby construction I mean epicormic shoots are, like this, valuable clue in our detective work as arborists.

Jad: 9:55

It's like the tree is sending us a message. Exactly. We need to learn how to decipher it.

Lilly: 9:59

Yes, and this brings us to another fascinating aspect of epicormic growth.

Jad: 10:04

Okay, what's that?

Lilly: 10:05

Their role in tree defense.

Jad: 10:07

Tree defense.

Lilly: 10:07

Yeah, so some studies have shown that epicormic shoots can help deter those browsing animals. Oh, really. Yeah, they can create this dense thicket of branches. Yeah, that makes it really hard for deer or other herbivores to reach those tastier leaves higher up in the crown.

Jad: 10:25

So it's like the tree is growing its own little army of bodyguards.

Lilly: 10:28

Yeah, I love that.

Jad: 10:30

I never would have thought about it that way.

Lilly: 10:31

It's just another example of you know the incredible adaptations that trees have evolved over millions of years. I mean, they're masters of survival and epicormic shoots are one of their most versatile tools.

Jad: 10:46

So we've covered a lot of ground here. We have Stress responses, types of growth, practical implications for tree care.

Lilly: 10:53

Yeah.

Jad: 10:53

Ecological roles, right Even defensive strategies.

Lilly: 11:02

Yeah, and I know there's even more to this topic. There is. It's a field of ongoing research, of course. But there's one more aspect of epicormic growth I find particularly intriguing. It's the connection to the concept of tree aging. They experience a process of aging, right, you know. As they get older they may experience a decline in vigor, reduction in their ability to produce new growth. But epicormic shoots can actually offer a way for older trees to kind of rejuvenate themselves, to sprout new growth and maintain their vitality.

Jad: 11:29

It's like getting a second wind.

Lilly: 11:30

Exactly, and this is why it's so important to consider the age of the tree when we're assessing epicormic growth. You know, those shoots might be a sign of stress in a young tree, but in an older tree they could actually indicate adaptation and resilience.

Jad: 11:46

So context is everything.

Lilly: 11:48

It is.

Jad: 11:49

We need to factor in the species, the age, the environment, the overall health. It's really like a holistic perspective.

Lilly: 11:58

It is, and that's what makes arboriculture so fascinating and challenging. We're constantly learning, adapting and striving to understand these complex living beings.

Jad: 12:10

And those epicormic shoots. They're a key piece of the puzzle. They really are, yeah, and the more we learn, the better equipped we are to advocate for these trees. That's right that we care for so much.

Lilly: 12:22

It really is all about, you know, seeing those epicormic shoots not as like this nuisance to get rid of.

Jad: 12:28

Right.

Lilly: 12:28

But as a valuable piece of information.

Jad: 12:30

Yeah. So if our listeners could walk away with just one key takeaway, okay, from this whole deep dive? Yeah, what would you want it to be?

Lilly: 12:37

I would say the next time you see a tree with epicormic shoots, don't just automatically think problem, I got to fix this Right. Take a moment really observe them. Okay, think about what they might be telling you about that tree's history, its health, its struggles and its triumphs.

Jad: 12:54

It's about shifting our perspective a little bit. It is Viewing those shoots as like allies in our effort to understand these trees.

Lilly: 13:02

And remember this deep dive is just the beginning.

Jad: 13:05

Right.

Lilly: 13:11

There's so much more to learn about epicormic shoots, their role in tree biology and what they mean for us as arborists.

Jad: 13:13

Absolutely Well said and I really hope our listeners are now looking at those you know just ordinary shoots with a new sense of wonder and appreciation.

Lilly: 13:24

Me too. It's amazing what we can discover when we just take a little time to look closely.

Jad: 13:28

So, to wrap things up, let's leave our listeners with a final thought to ponder.

Lilly: 13:32

Okay.

Jad: 13:32

As they head back out into the field. What's one question they should keep in mind?

Lilly: 13:37

Hmm, I would ask what is this tree trying to tell me? What can I learn from these shoots, and how can I use that knowledge to not just help this tree survive, but to really thrive?

Jad: 13:48

That's a really powerful question. It's a reminder that we're not just working on trees Right, we're working with them.

Lilly: 13:55

Yes.

Jad: 13:55

And those epicormic shoots are a vital part of that conversation.

Lilly: 13:59

Couldn't have said it better myself.

Jad: 14:00

Well, thanks for joining us on this deep dive.

Lilly: 14:02

Yeah, thanks for having me.

Jad: 14:05

Until next time, happy treeing.

Roger: 14:10

Thank you for joining us for this episode of Talking Trees. If you found today's discussion valuable, don't forget to stay tuned for more episodes. Your support helps us continue sharing knowledge about trees and arboriculture. We appreciate you being part of our community and we look forward to exploring more fascinating topics with you next time. Until then, take care and stay inspired by the resilience of trees.