The Secret Life of Mycorrhizal Fungi!

Chelsi Abbot, plant pathologist and technical advisor at the Davey Institute, joins us this week to talk about mycorrhizal fungi, including their relationship with trees, the different types and how Chelsi became passionate about fungal species. 

To find your local Davey office, check out our find a local office page to search by zip code.

To learn more about mycorrhizal fungi and other fungal species, read our blogs How Mycorrhizal Fungi Support Tree Health and List of Plant and Tree Diseases Caused by Fungi.

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Have topics you'd like us to cover on the podcast? Email us at podcasts@davey.com. We want to hear from you!

Transcript

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SPEAKER_01 0:00

Welcome to the Davey Tree Expert Company's podcast, Talking Trees. I'm your host, Doug Oester. Each week, our expert arborists share advice on seasonal tree care, how to make your trees thrive, arborists' favorite trees, and much, much more. Tune in every Thursday to learn more because here at the Talking Trees Podcast, we know trees are the answer. I'm joined again this week by Chelsea Abbott. She's a technical advisor for the Davey Institute. And like in the past, we are going to touch on fungi and all sorts of cool stuff. But the episode is called The Secret Life Below. Chelsea's laughing because I've had her repeat this top title about three times. The Secret Life Below, microrhizal fungi and the underworld underground network that supports tree health. Alright, Chelsea, I see you're clapping and laughing at me, not with me, but I deserved it for butchering that topic about five times.

SPEAKER_00 0:58

You stuck the landing though, so that's good.

SPEAKER_01 1:01

I don't think so. I think the uh the Russian judge would have given me about a 6-5 on that one.

SPEAKER_00 1:07

Pass fail, you pass.

SPEAKER_01 1:09

So mycorrhizal fungi, can

What are mycorrhizal fungi?

SPEAKER_01 1:13

we start there and kind of explain what it is?

SPEAKER_00 1:17

Yes. Um, so mycorrhizal fungi, I think many people might think of them as sort of the proprietors of the underground network. Um, so they are fungi that form associations with trees and other plants. The grasses can have uh mycorrhizal relationships. Uh, and what they do is they infect, for lack of a better term, these trees, but instead of becoming parasitic and feeding on the tree, they actually form a symbiotic mutualistic relationship with the tree. So they give a little bit of nutrients and extend the root system, and then the tree just gives a little bit of carbon back to kind of feed the fungi and also provide a home for them. So it's a symbiotic relationship between the fungus and the plant.

SPEAKER_01 2:13

For example, in my forest, which is a small, you know, it's four acres, all sorts of different trees. Is this all

Two types of mycorrhizal fungi

SPEAKER_01 2:21

going on underneath the ground? Yeah. Out there, and it does even though it's oak trees and sassafras and magnolias or whatever it might be, are these all interacting with each other or are there separate mycorrhizal fungi for each species? What's going on out there?

SPEAKER_00 2:40

Yeah, so it's a little bit of a loaded question, so I'll try to answer it as simplistically as possible. So generally there are like two, well, there's really three, but we're gonna focus on two groups of types of mycorrhizal fungi. There's one that are called the obuscular, or they're also called AM, and they're generalists. So they don't necessarily pick and choose, they kind of just form associations with plants that can benefit them, that they can then benefit back. But then there's other types of mycorrhizal fungi, and those are the ectomycorrhizal fungi, also known as ECM or EMF, depending upon where you might have read it. And these are much more specific host fungi, where they'll typically, for example, they'll really form with like conifers or birch, or some will be very specific to oaks. Uh, and so it's more about the crosstalk between the fungi and the host, the plant, that they've evolved with in those cases. So there are some generalists, and then there are some really more specific, I'll go after this one species and link up to another species type of fungi.

Can you see them?

SPEAKER_01 3:52

In general, is it something we can see or is it or is it microscopic?

SPEAKER_00 3:57

So, and that's a great okay. So, as far as the actual, like how are they connecting to the hosts and how are they improving the root system or uptake? Is if you think about fungi and you think about a mushroom, I'm sure, right? That's probably what you're picturing right now. There is an entire underground root system, for lack of a better term, of fungi called the mycorrhizae, or sorry, the uh mycelium or hyphae. And that's sort of like the root system of the fungi that grows underground and within substrates or within hosts. And so it's that mycelium or hyphae that's sort of extending the root system, and you don't necessarily see that because it's microscopic, but when it's time to reproduce and disperse, some of these fungi will produce mushrooms, and a lot of them are going to be single-stocked, gilled mushrooms that sort of pop up late summer through fall. And if you see a lot of singly growing mushrooms kind of just randomly growing around the root system of a tree, it's likely that those are mycorrhizal again, especially if they're in the late summer, fall time.

SPEAKER_01 5:05

Do we

Should we encourage it?

SPEAKER_01 5:06

or should we encourage or can we encourage mycorrhizal fungi?

SPEAKER_00 5:11

Yes, we should. And uh we we can. And I like to think about it as uh what was that baseball movie where they made the stadium and then people started playing on the stadium? It was in a cornfield or something like that.

SPEAKER_01 5:27

But I oh yeah, yeah, yeah. Yeah, oh gosh, it's Kevin Costner, I can tell you that.

SPEAKER_00 5:34

But you know, the whole they will build or build it and they will come thing. There you go. There we go. And so this is my take on mycorrhizae as well, is kind of build it and they will come. And so it's less about necessarily putting them there, it's more about building their appropriate home, which is gonna be, you know, soil that has good organic matter, well draining, has a lot of, I would say, um nutrient-rich. I just what I I what I don't want is high drought soil that gets dried and cracky and is super compacted, they're not gonna be super happy in that and they probably won't live there.

SPEAKER_01 6:15

So when we originally, when we're planting our trees and we find a spot that has you know better than average garden soil, we know that's a plus right off the bat, but that's also a plus because that's gonna be a good environment for mycorrhizae.

SPEAKER_00 6:30

Okay, yeah, that's exactly it. So it's kind of like whatever makes your tree happy, let's be honest, would make a mycorrhizae happy because it is symbiotic, right? Um, and so when we're planting, a lot of the reality is there's probably mycorrhizae already there, sort of ready to form associations, but they need to be in a healthy condition in order to

When did Chelsi become fascinated with fungi?

SPEAKER_00 6:50

do so.

SPEAKER_01 6:51

Over the past few years, you and I have talked often about different uh fungi. At what point in your learning career does this become something that you become fascinated with?

SPEAKER_00 7:05

Fungi in general?

SPEAKER_01 7:06

Yeah.

SPEAKER_00 7:07

Um, so I've always been a fun gal, as I like to call it. Here's a little play on words for you. Um so I've always been fascinated by plants and fungi. And I would say more specifically, I became um really taken by the relationships that they have around when I was eight years old. Um, that's when I started to learn more about okay, here's a fungus, here's a plant. At what point do they become a disease? At what point does it become a helper? And when is it just sort of a neutral relationship? Um, so I'd say it was pretty early on in my life that I was kind of like, this is just sort of this secret, nobody talks about, nobody knows what's going on. It's almost like mystical, this conversation between fungi and plants.

SPEAKER_01 7:54

So it's been a lifetime of learning about fungi, which I think is cool.

SPEAKER_00 7:57

Yeah. Um, but then of course, in my job as a plant pathologist, which is what I am, um, you know, I studied it in graduate school, and now I get to talk about it pretty regularly. So I'm I'm I'm living the dream.

Large fungal networks

SPEAKER_01 8:11

And as I remember, and let me know if I have this right or not, but a mycorrhizal fungi network at some point was like the largest organism.

SPEAKER_00 8:23

Is that do I have that right or what what what was so it so there's a there's a kind of a it's between two organisms that would be considered the largest organisms in the world. One of them is a, I believe, aspen grove, it's a clone, I think it's called like Pangea, uh, down in I think California. But what you're thinking of of the fungi is the humongous fungus, which is actually, I believe, in Oregon. It's like three square miles of underground uh network of a parasitic fungi, so not a mycorrhizae, it's actually a no-no. But it is a fungus.

Products with mycorrhizal fungi included

SPEAKER_01 9:00

And so I see in the nurseries now that different products will say they have mycorrhizal fungi included. Yes. Is that is that something that's good or is that possible? And or is that where we're do we want to add this to our planting hole?

SPEAKER_00 9:18

Yeah, so there's so it's it makes you think it would make sense, right? Okay, I'm I'm putting a new plant into a new space. Why wouldn't I also give it some fungi to form associations with? And this the kind of sad reality of that is that um there's no let's say guarantee that those mycorrhizae in that bag would actually form an association with that plant host because it's such a complex crosstalk that has evolved over time, getting it would be such a like a chance that you would be taking that they would even form associations. And then from a more let's say ecosystem standpoint, the likelihood is that the mycorrhizae, unless there's been a huge drought, a huge flood, or you've tilled the soil completely up, the likelihood is that they're already there and they're already kind of ready to go. That's why it's like it's better to sort of promote the existing mycorrhizae than necessarily add new ones in. And then if I can add a different sort of concern that I have about around adding in fungi that perhaps are not native or not there originally, uh what are what could we be adding into the soil that could be disrupting what's already there? A great example of this is there's a fungus that people have been growing for food. Um, I believe it's called the golden oyster uh mushroom, and it got out. And it's sort of wreaking some ecological havoc because it grows faster than all these other fungi out there. Um, and so it's kind of like sometimes with this, I'm like, I because I don't think it would form an association, again, unless there's been some kind of ecological disaster, the better bet would probably to promote the populations of microbes that are likely already there rather than adding potentially new ones in that could or could not form an association.

SPEAKER_01 11:14

Well, let's revisit that again for a second

What should I do to help?

SPEAKER_01 11:17

to help them. If it's already in place, it's already there. And in my like in my case, where I've got you know 50 trees out there in the forest, what should I do to help them?

SPEAKER_00 11:29

Yes. Okay, and so that's again, if you're if you're thinking about, I'm gonna assume your soil is perhaps poorly draining and compacted or something like that, just from an assumption of where you're at. So whatever might be, let's say, your soil, your soil sore points, whether it's highly compacted soil, poor nutrient, poor drainage, it's essentially just correcting those factors to create a just a better biome for microbes. Again, and your plant material probably will thank you as well. So that's why I say like whatever might help your plant is probably going to be helpful for the beneficial mycorrhizae that are within the ecosystem already.

SPEAKER_01 12:09

So if I'm mulching and I'm mulching the right way, we always have to reference that, Chelsea. We always have to reference mulching the right way, which means looks like a donut, not a volcano. That's as far as I'll go. People are probably tired of hearing about it. If I use compost as my mulch, that's gonna be a positive for everybody, right?

SPEAKER_00 12:33

Yeah. I mean, when you think about like any type of organic matter adding in, that you know, that's just fungi food, right? Um, and we're talking about different fungi when we talk about decomposers, but fun fact, a lot of mycorrhizal fungi can also slip into decompo decomposition stage. Um, if we go back in time, a lot of them at one point were uh decomposers and then they formed associations with plants. So they can kind of live on detritus and make associations with plants. So that's you're really sort of feeding that food soil web when you're doing things like adding in compost and and mulch appropriately.

SPEAKER_01 13:15

Is part of your job presenting this to arborists and

Not-so-good fungi

SPEAKER_01 13:20

people working in the field at Davy?

unknown 13:22

Yes.

SPEAKER_00 13:23

Um, I not only educate internally, but I also speak at conferences on beneficial fungi, not so beneficial fungi, and other things. Yeah.

SPEAKER_01 13:34

What are the not so good fungi? So those you mentioned one there that I when I was talking about this giant organism, but what are some of the other negatives?

SPEAKER_00 13:46

So a lot of the times those are the ones where we see them disrupting not only a normal biological function of a tree, like for example, a foliar disease that might cause defoliation, or a vascular wilt, which clogs up the vascular system. So things like oak wilt or Dutch elm disease, those are not so good fungi. But then I think what a lot of people think about is the wood decay pathogens, um, the you know, armillaria, which is the humongous fungus, which is a root rotter, or any type of trunk buttress, branch rotter that causes not only, you know, some decline, but really structural hazards. And so I think a lot of people focus in on the negative fungi, but those are very, very few percentage-wise of all the fungi. Most fungi are beneficial or neutral, and there's a small subset that are actually pathogens and they get a lot of our attention.

SPEAKER_01 14:41

That's interesting and fascinating, actually, because when we think about the garden, we know that most of the insects are beneficial or benign. It's just the ones that bother us that we seem to come come to the forefront.

SPEAKER_00 14:56

We tend to get really hyper-fixated on the bags, and we forget that 90% of them out there are actually doing a lot of good for us. There's this wonderful book, um, it's called Entangled Life, that really goes through everything that fungi do for us that just silently happening in the background. It's an incredible book. I can't recommend it enough if you're looking to get into any type of fungi knowledge.

SPEAKER_01 15:21

And

What's changed in the last few years with fungi?

SPEAKER_01 15:22

I was gonna ask you, too, with all the research and and uh learning that you're doing, what has changed in the last couple of years as far as you're concerned, as far as what you've been looking at, uh what you've been concerned about?

SPEAKER_00 15:37

Ooh, oh, well, so interestingly enough, I'm seeing a lot more uh parasitic fungi because it's a kind of a double whammy. As our climate shifts and we see some differences in our weather patterns, particularly in our precipitation patterns, hosts become more stressed. And then a lot of the precursor to, let's say, wood decay infection, specifically like root rotters and trunk roters, is water-related stress. And so you have a host that gets more stressed, and then you have a pathogen that can, you know, sort of slip into almost like more infection, more pathogenic mode. And so unfortunately, I am seeing a lot of more, I would say, water stress-related wood decay pathogens and canker-forming pathogens that are starting to show up on our trees. So that's that's newish.

SPEAKER_01 16:38

What do you do when you're

Fungi causing tree death

SPEAKER_01 16:40

walking by a property and you see something at the bottom of a tree that might indicate the death of that tree? How often do you speak up?

SPEAKER_00 16:52

Okay, so if I see a fungus at any time, I it's not as though I have to say, excuse me, please let me go look at this. I sprint over excitedly like a sprite because I'm a weird little plant pathologist, and that's just my jam. Um, so I don't, I never not speak up. But it is something, the one thing I will you know urge is seeing a fungus around a tree is not a death sentence. Um, it is not always a wood decay fungi. If it is directly attached to the woody tissue and there is obvious symptoms of rot or bleeding and canopy decline potentially, then I would definitely probably give somebody a call. But again, if you just see singly growing fungi around the root system or growing in the mulch, those are probably decomposers or maybe even mycorrhizal, which both are beneficial uh in their own way.

SPEAKER_01 17:47

So and this is something again, if you're worried about it, if you're seeing something sprout, get your Davy Arborist to come out.

SPEAKER_00 17:56

And take a picture because sometimes those things can be pretty uh quick to dissolve, and by the time you get someone out, they might no longer be identifiable, and that's always frustrating. So photos are recommended.

SPEAKER_01 18:07

They're always happy to look at a photo too, and if they see something they don't like, they'll be out quicker.

SPEAKER_00 18:12

Yes.

SPEAKER_01 18:13

Well, before I let you

Chelsi's love for her job

SPEAKER_01 18:15

go, I've I've probably asked you this every time we've talked, but what do you get out of doing this, Chelsea? Because you're you're always so happy and excited to talk about it, and I'm always so happy and excited to hear about it. It's always fun to talk with you. Tell us, tell us what you what what kind of satisfaction you get out of doing this job.

SPEAKER_00 18:39

Yeah, I mean, you've already sort of alluded to it, but I, you know, I'm a I'm a very curious person. I if I could, if for if any, if I won the lottery, I would just go back to school for the rest of my life. I just love learning. And so, with you know, the job that I have, in order to teach people, I have to learn first. And so a lot of my job in some some times of the year is just reading, reading papers, reading books, you know, kind of creating new connections and figuring out how do I translate this information for other people. So I myself am very much so like a fungi. I consume and then I disseminate. So I'm I'm the one the thing that you know sort of really got me jazzed as a kid. So I I think I think that's pretty clear that I just really enjoy talking about this type of stuff with anybody.

SPEAKER_01 19:29

And we enjoy listening to, as always, it was great to talk to you, Chelsea. And and I always learn so much, and I can pretend like I know what I'm talking about when I'm walking through the forest now with my grandkids, and I can point to this and point to that, and it's all because of you.

SPEAKER_00 19:45

I love that, and you know, and then eventually they'll point to stuff and teach other people what it is, and that's how it works.

SPEAKER_01 19:52

You got it. Thanks again, Chelsea.

SPEAKER_00 19:53

Thank you.

SPEAKER_01 19:54

It's always a joy to talk to Chelsea, and as I said, I always learned something and hope you did too. Now, tune in every Thursday to the Talking Trees Podcast from the Davy Tree Expert Company. I'm your host, Doug Oester, and you know what I want. I want you to subscribe so you'll never miss a show. And what should we be covering on this podcast? There's two ways to tell us. Send us an email to podcast at Davey.com. That's P-O-D, C-A-S-T-S at D-A-V-E-Y.com. You can also click the link at the end of our show notes to text us a fan mail message. Your ideas could be on a future show. We'd love to hear from you, and as always, we'd like to remind you on the Talking Trees podcast. Trees are the answer.