What's Eating My Oak Tree? A Guide to Common Oak Issues

Alec Hall from Davey's St. Louis West office joins us to talk about oak trees, including common diseases like oak wilt and sudden oak death, identifying resilient species, choosing the best oaks to plant and more. 

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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. The last time we talked with Alec Hall, a sales arborist from St. Louis West Davy Tree office, he was on vacation in North Carolina. But today, back to work, and uh we're talking all about the problems with oaks. And Alec, before we started talking here on the podcast, I told you about my problems with oak. So welcome back to the show. How are you?

SPEAKER_00 0:50

Well, thanks, Doug. Howdy, howdy, very good. Glad to see you again. Um, love talking about trees. So I'm in the right space.

SPEAKER_01 0:58

What is going on in St.

Oak wilt in St. Louis

SPEAKER_01 1:00

Louis referring to to oaks?

SPEAKER_00 1:03

Yeah, I so you know I don't want to I don't want to focus just on the negatives, Doug, but uh there are a number of damaging diseases that anecdotally I can say seem to be on the rise. Um one of which is oak wilt, like you mentioned with uh with your own with your own oaks uh at home. So um that and uh some other things that you probably heard of, phytophtherist, sudden oak death, uh oak uh oak gall, gouty and horned oak gall. Um so there's there's there's quite a few issues that we're running into uh currently, particularly with our our red oak species.

SPEAKER_01 1:39

Do we know why we're seeing more of it, or is it just one of those things where things come and go?

SPEAKER_00 1:46

You know, I I don't know. I so I've been I've been working as an arborist for 15 years, and I remember the first time that we identified oak wilt here in St. Louis, um, at the time one of the more senior arborists almost didn't believe that it was here, right? So there was certainly a time where either it wasn't here and we weren't seeing it, or we weren't diagnosing it um to the degree that we are now. It it's it's hard to say, and I don't have any real info on that. I think that one of the uh one of the possible contributing factors is that a lot of people people know to prune their trees now, right? Maybe that was a bit more rare 50 years ago. Uh, but uh it's not rare to prune your trees these days, and that's one of the uh possible ways that uh transmission uh possible way to transmit the uh the oak wilt disease. Just a guess. I'm just talking out of cuff. No no research on that, Doug.

SPEAKER_01 2:39

But it it makes sense.

SPEAKER_00 2:40

Yeah.

SPEAKER_01 2:41

So how do I know if I

How do I know if my tree has oak wilt?

SPEAKER_01 2:43

have oak wilt uh on an oak?

SPEAKER_00 2:45

So oak wilt is just acutely damaging, right? So um even an untrained, I not that you are Doug, but perhaps someone who is, um, if their tree just acutely starts to turn color and drop its leaves uh this time of year in the summer, there's a good chance that at the very least you should have it checked for oak wilt, uh, because there's consequences to the surrounding oak trees, of course. Um, but uh but yeah, it it's the most acutely damaging disease that I know of in oak trees. Uh it's not normal for an oak tree to die over the course of two weeks. Yeah. Unless it has oakwilt.

SPEAKER_01 3:24

And so

Spreading oak wilt

SPEAKER_01 3:25

is this something that spreads to other oaks that are close to it?

SPEAKER_00 3:30

Or yeah, so the two the two primary uh mo modes of of transmission are going to be um underground by the roots, because trees, as you know, their roots will graft together. Uh so that's one way that it can spread. Um, but the kind of the primary way it spreads above ground is actually by a sap-seeking beetle. So the uh the oak wilt fungus, uh, when it's under the tree, it's it's kind of sweet and it attracts the beetles, right? So they'll they'll go to that fungus and it sticks to them, and then they're attracted to the wounds of other oak trees, and that's that's the way it transmits. So the vector is a beetle, not unlike Dutch Elm disease, for example.

How to avoid oak wilt

SPEAKER_01 4:10

First off, is there any way I can avoid it?

SPEAKER_00 4:14

There is. If you have if you have a particularly particularly high value oak tree, such as, you know, right in the front yard or something like that. If you have a particularly high value oak tree, it would be reasonable to put fungicide in that tree annually to protect it. Now, I understand that um, well, perhaps you and others might understand oakwill is not not super common. You are a bit unlucky that it it kind of happened to you. It's not particularly common as long as we don't prune our trees during the summer and things like that. But if you have a particularly high value tree, it's it's worth the investment to just pre-treat it like you would an ash tree or any other number of uh damaging diseases.

SPEAKER_01 4:57

So I've talked about it at length here on the podcast that I do live on four acres of lots of oaks, and oak wilt has moved in. But it's not like killing all the trees. I lose sometimes one or two a year, sometimes none. Uh, it seems that my underground issues have been stopped by the driveway for now.

SPEAKER_00 5:22

Oh, yeah, it's that's awesome. Yeah, good point there.

SPEAKER_01 5:25

Uh, but in my case with this infection, I I've got too many oaks to treat, and the only way I can really deal with it is removing the trees once they're dead, and then removing that wood and getting it out of the area. But it's not like you said, it's not like all the trees in you know two weeks die. It's it's right, it's it's not that kind of of spread. Is that what you're seeing where you're at? If if somebody has it, uh it's not the whole forest, but it it does work its way through the forest.

SPEAKER_00 6:03

That that's exactly what I see here. Is generally it will be one the the first oak tree goes and the second one or some of the other oak trees that are perhaps you know sharing a root graft or nearby. Um no, you don't normally see them both go at the same time. That's that's abnormal. You may have such a high density in your forest that you may see more than one go, right? Uh, but that's very unlikely to happen um here. But uh yeah, I tell my clients to expect that uh, you know, if you lose one and the other one, if it can't be treated or for whatever reason, or the root grass can't be severed for whatever other reason, you may expect that it will it will contract the disease as well.

Removing oak trees

SPEAKER_01 6:45

In that case that you're talking about specifically there, would you consider removing the other tree or would you just want to wait to be sure that it gets the problem?

SPEAKER_00 6:55

I I mean this it's a it's a it's a personal choice, right? But I would say if we're if we're not wow, this is a tough one, Doug. Yeah. Yeah, well, but there's kind of a responsibility question here, right? Or or or an ethical question here. And I I I think I would I would have to think on that. I I'm not quite sure if I would prematurely remove an oak tree uh just because there may be an expectation of infection. I'd have to think on that, Doug.

SPEAKER_01 7:22

And I it would also be case by case, yeah. How close is the tree? How does it look? Uh what's it gonna cost to come back and do it? You know, though.

SPEAKER_00 7:32

Do I have neighbors that have oak trees? I mean, all these would have to, you'd have to think about all those things.

SPEAKER_01 7:37

You know, I've warned my neighbors.

SPEAKER_00 7:39

And and that's the right thing to do. Yeah, you should. That's the right thing to do.

SPEAKER_01 7:43

Is there a certain type of oak tree

Which types of oak trees are most affected?

SPEAKER_01 7:45

that gets the disease more often than others?

SPEAKER_00 7:48

Absolutely. And some of this may just be the type of oak trees that I have here locally, but uh generally oaks in the red family are going to be, from what I understand, more susceptible. We see pinoaks here more than any other, which is a type of red oak, right? Or in the red oak family. Um we see pinoaks get it more than any other type of oak. Although we do see other, you know, shingle oaks and northern reds and whatnot get it too. I personally have never seen um I've never seen it in a white oak, but I know that they can contract the disease.

SPEAKER_01 8:18

Okay. And do we have any science that tells us why reds get it worse than the other ones, or it just that's just the way it's worked out?

SPEAKER_00 8:28

I I think I think there is science behind it. I don't know it, so I'm not gonna speak on it, but it has something to do with a chemical called tyroses, and I'm just gonna have to leave it at that.

SPEAKER_01 8:38

So I I did a uh podcast about IDing trees, but I have to admit, Alec, that I couldn't tell you the difference between a red or a white. I just I don't know. I should know. I should you have four acres. I know, but I know I know I should know, but to me they're all oaks, and that's I'm sure to you sounds like oh, what an imbecile this guy. This guy hosts a hosts a podcast about trees. He can't tell the difference between a red and a white oak. And I've been told a couple times, you know, I should just go out, look at the leaf, take a picture of the leaf, and I know I could figure it out in a minute, but I just I haven't.

SPEAKER_00 9:20

Well, I tell I tell you, you get real good at it and you can do it by the bark. So just practice, practice, and you'll be you'll be knowing what they are even in the winter time.

SPEAKER_01 9:29

Besides oak

Phytophthora, or sudden oak death

SPEAKER_01 9:30

wilt, what other problems are you seeing in your oaks in your area?

SPEAKER_00 9:34

So uh again, kind of an anecdote here, but a huge uptick, and I don't know if it's just because of uh our ability to to more accurately diagnose it or not, I don't know. Uh, but phytophthora, um, which is associated with something called sudden oak death, which I'm sure you and your viewers have have probably heard of. Um Phytoptera is a bleeding canker that occurs on oak trees. And uh it's it's it's again, it's very it's it's it's acutely very damaging.

SPEAKER_01 10:02

And how do I identify it? Do I just look up one day and my tree's dead? Is it that clear? Is it that clear?

SPEAKER_00 10:09

Here's how I identify it. So if you see on the trunk of your tree any kind of uh sap exuding from the the lower trunk, I go up to it and I smell it, okay, uh, because it's always one of two things. It's either what we call bacterial wet wood, which implies a fermentation in the tree. So you can imagine that may have a uh that would have a particular smell because of that fermentation. While Phytophthera uh does not have that smell because it's not caused by a fermentation. Um that's one of the diagnostic tools, if you want to call it that, that I use.

SPEAKER_01 10:43

When do you get a call about something like that? Is it when the tree is too far gone?

SPEAKER_00 10:48

Always when it's too late. Here's the thing. I catch these things on the daily, I'll catch these things when it's not too late, right? And uh luckily we can we can save those trees. Um but typically for the average person, they don't spend their days looking at trees. It's just not their interest, right? So they don't know something's wrong until something's very wrong. And many a times it's too late. So what I would tell people, just like I do with my car mechanic, I don't know anything about fixing cars, right? Uh, I would just have an arborist look at your stuff annually, right? That's it. That's all you got to do.

SPEAKER_01 11:27

If you do get this problem, but you get it early, how are you solving

Treating sudden oak death

SPEAKER_01 11:33

it?

SPEAKER_00 11:33

So with with phytophthora in particular, um, we treat it with uh something called phosphite or phosphorus acid. Phosphorus acid. Phosphite is good enough, phosphite. Um it it it it it stops the spread of the disease, although there is this is still something that has to be applied kind of on a continual basis as symptoms persist.

SPEAKER_01 11:55

Besides that, is there any other way to deal with the problem?

SPEAKER_00 12:00

Yeah, so phy Phytophthora is what we call an oomycete. So it's a um it's a fungus that moves through water. And many a times when these oak trees become infected with it, um, it's it's uh it festers or or maybe it's precipitated by uh by too much water in the area. So in addition to that chemical component, uh, insofar as treating the disease directly, we can decompact the soil, for example, to you know increase the rate at which uh water can move through it.

SPEAKER_01 12:27

And

Planting red oaks

SPEAKER_01 12:28

at this point, are you still planting red oaks? I mean, is that an okay plant to put in for us?

SPEAKER_00 12:36

Here, yeah. I mean, we're planting red oaks. We're not we're not planting pinoaks anymore, for the most part. Um, of of that's that's one particular type of red oak that we just here in St. Louis we don't plant very often anymore.

SPEAKER_01 12:48

Well, what other problems do you see in your oaks in that area?

SPEAKER_00 12:52

Yeah, so lastly, and this is this is kind of a big one

Gouty and horned oak gall

SPEAKER_00 12:56

and um a little bit uh a little bit less easy to treat, but but gouty and horned oak gall. I have you seen have you heard of that or or seen that where you're at?

SPEAKER_01 13:06

Not at all, but I'm sure it's here.

SPEAKER_00 13:07

Yeah, well, I mean, here's the interesting thing. I talked to arborist friends in different states, and it doesn't seem to have uh the same effect. Uh a lot of people don't know what it is, but here in St. Louis, there's a growth that we get on our pinoak trees in particular that over the course of time um does indeed lead to their decline. And it's it's quite damaging. Um with this particular uh disease, it's caused by a wasp. So what will happen is that the uh the females will lay their eggs into the uh new young stems of the tree, and the tree will respond by encompassing those eggs in kind of a gouty growth in which the larvae will uh then you know go through their life cycle and reinfect the tree over and over again. Unfortunately, there's not great treatment for these, uh, for for this type of disease or for these wasps. Um there is some things that we can do, but um studies have been ongoing and uh going on right now uh about how to best approach this uh this disease, which will probably reach you at some point. Maybe it has, and I don't know about it.

SPEAKER_01 14:13

Uh how about basic tree

Basic tree health

SPEAKER_01 14:16

health? Is that going to help these trees fight off these problems? Or regardless, if if that problem comes in, even if you got a healthy tree, you could be in trouble.

SPEAKER_00 14:29

Yeah, so with with oak wilt, you know, basic tree health, you know, of course you you you you know the deal. Keep your soils healthy, fertilize, you know, humates, keep your soils healthy. But um oak wilt is is is not I think I think it it a healthy tree is just as susceptible, just given the the transmission method, right? Uh there's nothing you can do about a root graft. Um so so that would be that would be an example of something that probably can't be uh fixed by tree health. And again, I'm not telling you not to take care of your trees, Doug. Definitely take care of your trees. Uh but uh but some of these things are just so damaging. I mean, that's why we're talking about them, right? They're just so damaging that um you're not gonna get away with uh not gonna get away with not having that arborist come by annually, you know.

SPEAKER_01 15:13

Tell me about being on a

Telling homeowners bad news

SPEAKER_01 15:15

property when you gotta tell people this, when you got to give them bad news. I know a lot of times arborists give good news, but there's these other times with with these oak problems that you have to give bad news. That can't be fun.

SPEAKER_00 15:29

No, it's it's it's it's not fun at all. And I I've been doing this for many number of years, and I do my best not to engage in hyperbole. Um, but sometimes uh there's just no choice, uh there's no choice but to let somebody down. And and and the attachment, you don't know the attachment someone has to their tree until you know. Um as an example, I had a uh I had a a lady, a friend of mine, really, that uh yesterday I had to tell her um to remove one of her oak trees. Um and she uh she was in tears. Uh she had to hang up the phone. It was uh because she's she's that tree's been around since she was a child, right? It was her grandfather's tree. So you never know. Some trees, not a big deal to take down. I'm sure you got plenty in the woods that you can uh you'll be all right if you lose one. But for some people, that oak in the front yard that's 200 years old, there's just there's not a you can't, you know, it's uh it's it its value is infinite, you know. So yeah, it's a difficult conversation to have.

SPEAKER_01 16:26

Well, I don't want

Why you should plant oaks

SPEAKER_01 16:27

to finish on a sad note, Alec. Let's talk uh why we should be planting oaks because they are pretty amazing trees.

SPEAKER_00 16:35

Yeah, no, absolutely. So I think I get I get this question a lot where you know people have to cut down a tree and they say, well, what what should I plant next? And and many a times, um the question for me comes down to how quickly do you need that tree to reach maturity? And if the answer is I'm planting this tree for the next generation, or I'm planting this tree for the next many generations, the responsible tree to plant is generally going to be in the oak family, right? Because they're trees that can last as hundreds of years. So it it's it's absolutely great for the environment uh to plant oak trees. Um and that's what that's one good reason. Now, not all of them grow fast. So sometimes we're planting for our grandkids, right? Uh, but somebody has

Swamp white oak

SPEAKER_00 17:23

to.

SPEAKER_01 17:24

What are some of your favorite types of oaks to plant when you find the right place for them?

SPEAKER_00 17:30

This oak, uh, not a very attractive name, but the uh the swamp white oak uh is my favorite type of oak tree to plant. Perhaps you've heard of it. Um they I live in St. Louis City, so I have perhaps different uh different needs than you would need uh with your oak trees in a more rural area, where I need my oak trees to be able to overcome the stressors of the concrete and the compaction and the lack of water and everything else, right? So swamp white oaks, they are very resilient and uh they're great for urban environments if you uh if you're not impatient.

Planting oaks on your property

SPEAKER_01 18:11

So at my age, I am planting for the next generation, but when my oaks go, Alec, I'm reaching for other varieties, I'm looking for mostly natives and trying to just put a little bit more uh variety into the forest. Uh that's that's my my thing now until until I can't plant anymore. So totally understand. How about for you? If you had a forested area and you were losing oaks, what would be a couple things that you would think about planting that you might like? I always like to pick brains of uh of arborists because I can get some good ideas. I put in American horn beam, I've put in sour wood, I put in uh I just put in a buckeye.

SPEAKER_00 19:02

Here in Missouri, and this is going to be a little bit different everywhere, right? Uh here in Missouri, I quite enjoy, and this is this is going to be controversial, so don't hopefully nobody in Missouri plays this podcast. I quite like hackberry trees, and they are a good native tree that, as far as I know, are very disease resistant, right? Um, I like hickories as well. So some people think of hickories as you know a great um a great wood for making things, but I also think they're a great tree. I like my pignuts and I like my shag barks. Um, even with you though, with the oaks, I couldn't help but wonder, is there a way to contain, you know, because I it would be so great if you could get oaks back in there um long term, you know.

SPEAKER_01 19:46

I'm just afraid to plant them because I know I just don't know. Like you, like I said, maybe that driveway is stopping it from, but but it could go around the driveway behind the garage. I I don't know.

SPEAKER_00 19:59

I get it.

SPEAKER_01 20:00

Yeah, but I appreciate those uh suggestions because I've heard a lot about hackberry when I talk to arborists, uh how that how they like it as uh uh a tough tree. And I do love my shag bar kickeries. Absolutely, yeah, absolutely. All right, Alec, that was good stuff. I appreciate uh your time, and it was great to talk to you again. We need to talk a little sooner next time. We uh yeah, absolutely.

SPEAKER_00 20:25

Let's not wait two years.

SPEAKER_01 20:26

Yeah, I enjoyed talking to you. So thanks again, and and we will talk soon.

SPEAKER_00 20:30

Cool. Thanks so much, Doug. You have a good afternoon.

SPEAKER_01 20:34

Oh, the plight of my oaks. Are you tired of me talking about it? Let me know. There's a couple different ways to do it. You can send us an email to podcasts at Deby.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. I want to know. Do you want to hear more about oaks? Do you want to do you want me to be quiet about my oaks? Let me know. Now tune in every Thursday to the Talking Trees Podcast from the David Tree Expert Company. I am your host, Doug Oester, and as always, I want you to subscribe to the podcast so you'll never miss a show. And as always, we like to remind you on the Talking Trees Podcast Trees are the answer.