Talking Trees with Davey Tree
Your trees and landscapes require year-round care, and The Davey Tree Expert Company is here to help provide you with expert advice. Join our professional Davey arborists and gardening-expert host Doug Oster to learn all about caring for your properties. We'll talk about introduced pests, seasonal tree care, tree diseases, arborists' favorite trees, how to help your trees thrive and everything in between. Tune in every Thursday because here at the Talking Trees Podcast, we know trees are the answer.
Talking Trees with Davey Tree
Drought Recovery: Why Some Trees Bounce Back and Others Don't
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Can drought affect some trees more than others? Will Johnston from Davey's Austin office joins us to explain how root systems, soil conditions, traits and more influence how different tree species respond to drought, and why some are more likely to recover than others.
To find your local Davey office, check out our find a local office page to search by zip code.
To hear more from Will Johnston, please read/watch:
- What To Do With Your Leaves
- Keeping Your Plants Alive in Texas Heat
- Tree Dormancy in Trouble in Austin
- How Oak Trees Benefit Austin, Texas
To learn more about drought, check out:
- How to keep your trees healthy during ongoing drought
- Drought, heat ease, but effects could linger across counties
- Why Some Trees Recover After Drought and Others Don’t
- What Should I Do with My Trees in a Drought?
Connect with Davey Tree on social media:
Twitter: @DaveyTree
Facebook: @DaveyTree
Instagram: @daveytree
YouTube: The Davey Tree Expert Company
LinkedIn: The Davey Tree Expert Company
Connect with Doug Oster at www.dougoster.com.
Connect with us: podcasts@davey.com.
Welcome
SPEAKER_01Welcome 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 by Will Johnston. He is the district manager of Davies South Austin, Texas office. And today we're talking all about drought recovery, why some trees bounce back and others, well, they just don't. Hey Will, how are ya? I'm doing good.
Austin's rain then sudden heat
SPEAKER_01Tell me about your climate there. What's going on? Are you guys been in a long drought or you've got rain? What's going on?
SPEAKER_02Well, it we're definitely in a great climate to be talking about drought. We've had a weird year, and it's Texas, so every year is going to be completely different than the year before. Um, but right now we actually had, weirdly enough, a very rainy spring with cool temperatures, and then a pretty rainy early summer with warmer but not hot for Texas temperatures. And then all of a sudden we get to August and the rain just shuts off, and the temperature jumps to like 100, 102 every day, and it's just been brutal on the poor trees down here.
SPEAKER_01For the your spring and rainy summer, wasn't that a great feeling for you because it has been so dry there? Do you look at it like the same way like a gardener would be like and a homeowner would be like, oh, this rain, thank goodness, because it's been so dry. Is it the same for you guys like as working with trees?
SPEAKER_02A hundred percent. Yeah, we we get stoked when we have like a rainy summer because we get to see a whole lot of growth. Um, in the past, you know, the six years in Austin that um I've been kind of on the arborist side of things is been drought, drought, drought, drought, and then a rainy summer the past two years. Um, and it's just crazy the amount of difference that you see in the growth rates on trees when they get a whole lot of rain. You know, we I had trees that I didn't really see grow much in the past four years that have now, you know, had two feet of new growth on it in the span of four months.
SPEAKER_01Well, it is fascinating to see how trees respond. And that sounds that sounds absolutely brutal. I hate drought conditions. Um, where I'm in in the east here in Pittsburgh, we've had the rainiest season I can remember. I can remember in 40 years. I have only watered my hanging baskets once. You know, you know, a hanging basket, that thing should be watered every other day. That's how much rain we're getting here. It's weird.
The post-rain canopy crash
SPEAKER_01Uh so when the rain shut off there, what are the is every tree just kind of does what? It like stops doing what it was doing, or does it jump into an early fall? What happens when the rain stops?
SPEAKER_02Um, at first you still kind of get growth. And what's been interesting this year is you know, there to me, there's a difference between uh a just dry summer from start to finish and a beginning rainy summer and then you know ending in a drought. Um But yeah, what we saw is these trees put on all this flush of growth. It was like, you know, I kind of treated it like investors in a business. Suddenly everything's looking great, and so these trees are like, we're gonna grow more leaves, we're gonna photosynthesize more, we're gonna put in all this growth, we're gonna make a bunch of extra energy. This rain is never gonna end, and then it just stops. And it's like the trees kind of panic. And suddenly we were getting a lot of calls from homeowners saying, Hey, can you come look at my tree? We we looked at it two months ago, and you're talking about how great it is, and now it looks kind of thin. And I would go out there and realize you know, some of the live oaks and pecans were doing this. They the trees started realizing, hey, I I need water to grow, and I don't want to be growing without water, and now I don't have any water, so I need to dump you know a third of my canopy. And so we saw trees maintain tip life at the tips, but you could see a whole lot more sunlight through them. And so what we realized is the trees just kind of front-loaded a whole lot of leaf development and then realized, whoa, we we can't sustain all of this with the water we're getting. We got to cut our losses, and that and that's what we saw. Um, as opposed to a summer where it's dry the whole time, they're just thin, right, from start to finish. They don't put on this whole flush of leaves. So it's it's really cool when you start looking at these trees day in, day out, and realizing how much they truly do adjust, you know, day to day or week to week to the environments they're
Pecan trees
SPEAKER_02in.
SPEAKER_01That's interesting. School me on pecan trees. I don't know anything about them. Is that like a common tree in your area? How is the pecan tree used? And do you get like the nuts off it and everything? You can't.
SPEAKER_02If you can beat the squirrels to them, you the pecans are yours. Um the the pecan tree is the state tree of Texas. And I had an old boss, great guy, a real institution as far as tree care in the Austin area. And he would say, I don't know why the state picked pecans as the state tree. Because they're just famous for getting really tall, and I love them. They're beautiful and super shady in the summer. I swear they're cooler to stand under than any other tree, and I couldn't tell you why. Um, but they drop limbs all the time. It's a competition between pecan trees and cedar elms, as far as which trees making me look like more of a fool to some of my clients. Because they'll just drop a random limb and it's a big limb. And so then the homeowners are going, Well, can you trim it to not drop any more? And I'm going, well, we can try. But it's somewhat of in a pecan's nature, but they do they produce those big pecan nuts and they grow these big long limbs. And so what happens is kind of late summer, fall when the pecans start forming, is it's like hanging buckets of water out of the tips of these limbs. So they're just prone to breaking, and the wood isn't the strongest, anyways. Um, but what I love about them, they're river trees. They grow. If you go to Mississippi, you'll see pecan trees that make Texas pecans look silly. They're just giant and magnificent. They really are water-loving swamp type trees. Um, and we just they grow big in Houston, but when they get near water, they're like cottonwoods. You can find a 70, 80 foot tall pecan in Texas, which is unheard of for trees normally. Um, I mean, you know, East Texas, totally different story. Texas kind of sits in this, it's big enough that there's a couple different ecoregions that you cross. So you get to see different trees, and plants in some ecor ecoregions will do different things depending on you know which one they're in. Um, but in Austin and some other places, if they're near a spring, or you know, we're in the Edwards aquifer, so we have these low water tables. So you'll have these like flat, kind of aridy, scrub brushy areas, but these pecans will set up, tap into that water table, and then just get huge. And so you'll get these giant, tall trees, and then you know, nothing taller than maybe your your hips or your knees, other than that. So there's there's some really cool stuff about them.
Pecan's straw roots
SPEAKER_02Um they if you want to let me keep talking about pecans, I've got they they do weird stuff with the roots, like they'll find live oaks typically spread out, right? And they stay shallow for the most part, and they just go in every direction. When you have a live oak, you know that its feeder roots are just everywhere in your foundation, popping up your sidewalk, in the neighbor's yard three doors down, right? They just spread out, but it's predictable in the fact that they go in every direction. Pecans kind of do that, but when they find a good source of water, they'll send like one big straw down into that water, and that'll be their main artery of life. And so we'll and they'll go, you can find a giant pecan root way farther away from that tree than any of the other trees. Normally, the rule of thumb is as you get farther away from the stem of the tree, right, the diameter of the roots gets smaller. Not with pecans, right? If they've got a little creek that they get their water from, you can find a giant root near that creek. And the reason we know is we were involved in a project years ago. We were brought on kind of at the later end, but they had these, there's a creek that runs through the university called Waller Creek, and they were pecans way out of the way. And the university needed to put in a new parking garage, I believe it was. And so they, you know, they dug down to build the underground sections of the parking garage, and they found these big roots and they didn't know what they were, but they weren't in the tree protection, you know, they they weren't digging in the tree protection zone, so they just cut them and and kept building, and then suddenly there were these three pecans way off in the distance at all in the span of like two weeks turned completely brown. Um and so it's just I mean, they're cool trees. They I like the trees that don't follow all of the conventional rules.
SPEAKER_01That is so cool. That's what I love about interviewing guys like you, Will. That is just such an interesting fact about that tree and the way you explained it, a straw. That that says it says it all. That is so wild. That is so cool. Now, when people plant that tree, is it just a shade tree? Is that what they're thinking? Or are they are they are they getting it, are they planting it for the nuts or a beauty, or why do you think they're planting the that state tree? Well, I would plant it just because I like them um for the shade and the looks.
SPEAKER_02Most people don't plant them, right? Because they have a they tend to have a reputation of dropping big limbs. And if you have a house near your pecan, any arborist with any sense, including me, will say, you know, maybe you don't pick the pecan. But people will do it, and a lot of times it is for the pecan nuts. Um, there's also, I mean, all over the place, I think Brownwood has a lot of big pecan orchards, but all around kind of central Texas, the Gulf Coast Plains, um, you'll run across pecan orchards where yeah, they'll plant them and harvest them for pecans. And now out there, they don't ever let them get very tall, right? They they they top them and do all kinds of things that as a residential arborist, I uh it freaked me out.
SPEAKER_01But um you want to be able to get the nuts, is that the idea? You're pruning it for production, right?
SPEAKER_02Yes, yeah, it's production pruning, and I think keeping it more manageable, you can shake them when they're small, right? You know, all kinds of different stuff.
SPEAKER_01So since we're talking about trees that do do and don't bounce back from a drought, the way you're explaining that pecan
How do pecans respond to drought?
SPEAKER_01tree, it loves water, how does it respond to a drought? That's a good that's a good tree to ask.
SPEAKER_02Um, because normally pecans are weird. So they when there's a really bad drought and the heat cranks up, they do to the extreme what I described about, you know, where they just drop a bunch of leaves, but they keep the tips green. You know, they really offload um their their canopy cover. But because they like to tie into consistent sources of water, they normally do pretty fine in a drought. You know, not it's not like there's red oaks, for example. That's a classic tree that when there's a drought, they are having problems. Pacamans don't really, but we had a situation here where it was so dry for so long in 2023 that the water table was not being recharged quicker than it was being used, and so it dropped. And so we saw, especially kind of in the South Lamar, Barton Springs intersection, we saw a bunch of pecans that were had been there for hundreds of years, looked great, just suddenly give up the ghost. And what had happened was what what we think is the water table dropped out from where their straw was at. And that was that was it. You know, they kind of have like one or two big investment routes, and as long as you protect those, you're fine. But if something happens to those, it's calamitous.
SPEAKER_01Wow, and then you mentioned Red Oak,
Red oaks and the drought fungus
SPEAKER_01they hate drought. Will they come back, or you never know if they're gonna give up the ghost?
SPEAKER_02They they have issues. Um, they're not resilient, is maybe the word the the the institutional word. What am I trying to think? The the word for a tree that doesn't bounce back from stress in general, but drought is a great just example of what stresses out a tree, and red oaks don't like it. Um they've been in decline in my area since I've been in the area. We've just had too many freezes, too many droughts, too much just rough stuff, too much urbanization. Um, but yeah, when they start to have issues with drought, you'll see tip dieback. There's a fungal disease that's known as the drought fungus. And that's a little bit of a misnomer. It's uh it's called hypo, well, the new used to be called hypoxylin. When I was first working in Austin, it was called hypoxylin. And then a bunch of scientists got together and realized that it's actually called bisconioxia. And I'm sure in 10 years it'll have a new name because that's just how that's just how mycologists work. Um but uh the hypoxylin canker, as I know it, that's what I always call it. Um, but if anybody knows it is bisconioxia, that's what I'm talking about. It um, known as the drought fungus, a bit of a misnomer. Really, it'll show up on any tree that's stressed, right? It's probably inoculated most trees in the central Texas area. I would suspect if you deal with it regularly, every tree gets it. And it's a weak little fungus, the tree will be inoculated with it. The tree will keep it suppressed, and as long as that tree is relatively happy and doesn't deal with anything but minor stress, nothing ever happens. But when this threshold of a certain level of stress happens, that fungus will begin to manifest itself on the trunk, the limbs of the tree, and it eats the cambium and causes pretty rapid decline in some cases. Um, red oaks are regularly get hypoxylin. They're they're one of the first trees that when a customer calls me and says, Hey, my red oak's not looking great, can you come look at it? I'm immediately looking for um the gray, tan to gray to black fungal mats that'll form. Um and if you get those on a limb, you can cut the limb off, water that tree as much as you can, give it phosphates, you know, amend the soil with biochar and compost and humates, and just do everything you can and save the tree. But my old boss, who's a big mentor of mine, he had this tagline that when he was talking about hypoxicline, he said, if it's on the branches, we can save it. But once it shows up on the trunk, it's it's time to call the coroner and not the doctor. Because at that point, it's just it's where it needs, it's at the essential vascular point where once it starts closing off that vascular system, the whole tree can't get you know, water
Will's mentor and Davey journey
SPEAKER_02and sugar and everything else it needs.
SPEAKER_01Well, tell me this boss's name. Who is this guy and what did he mean to you coming up in this business?
SPEAKER_02Uh his name was Dave Madden. Uh, he meant a lot to me. He actually, I went to AM, which is weird to work in Austin being an Aggie, uh, but he was also an Aggie, and I was taking a class back in 2017 called Intro to Abora Culture, taught by another great arborist named Todd Watson. And Todd said, Hey, you know, guys, you should really polish up your resumes for this career fair coming up because Davey's gonna be there, and that's a great company. So I walked out, I handed my resume to Dave, walked back into class, finished class, and got a call a few weeks later, interned at Davey with him. And then he brought me back when the internship ended, worked for Davey ever since. He was he's just he was an awesome guy. He started, he went to AM, graduated in I believe '79. His family owned a pecan orchard. So he worked on a pecan orchard for two years, decided that he didn't want to do that, interned with a company in Austin called Caldwell. Worked for Caldwell till 1999 when Davey acquired them. And so then Davey acquires Caldwell, they get Dave as part of the deal, and he sticks around till 2022 when he retires at December 31. And I still text him. He sends me pictures of all the vacations he goes on. And I tell him that the office is, you know, the walls are still standing. Um but yeah, he was a great guy. And I mean, working for Caldwell is interesting because it Caldwell was the big uh tree company of tree companies in Austin. They started in 1931, and the story goes that Mr. Caldwell actually was an employee of John Davy, who was trained and mentored by John Davy. And the University of Texas called the Davy Tree Company at the time and said, We want an arborist to maintain our campus. So John Davy tapped Mr. Caldwell to go, and kind of as Mr. Caldwell's leaving, he goes, you know, I'm not gonna, you know, pick up my roots and go to another city for another company. I'll go, but I'm gonna start my own company. And so that's what he did. And he had this signed um, he had a signed copy of the Tree Doctor. And so then when Davey acquired it in the 90s, they all, you know, everybody kind of realized what had happened. So it was a great, I wasn't there for that, but it was a great uh photo op, according to Dave.
SPEAKER_01Well, not only are we learning about drought, about uh working with uh a mentor, we're getting some Davy history too, Will. This is pretty, this is pretty good stuff. Uh let's get back to the the trees and their uh reaction to drought. What about
Why do live oaks endure drought?
SPEAKER_01live oaks? Live oaks are a big deal down there, right?
SPEAKER_02Yeah, oh yeah. They're a big deal. And they're big rule breakers as far as the tree world goes. They don't ever, every piece of conventional wisdom we have, the live oaks seem to challenge it. So they are probably the more tolerant trees of drought stress. But it comes with some caveats. You know, there is no tree that can handle or plant that can handle the extreme drought. And we've had a couple extreme droughts in Austin, so live oaks do suffer from it. But as I was talking about them earlier, they they spread their roots out everywhere, right? They, I mean, they go three to four times past the drip line of the tree. They spread out anywhere you can get, right? I have homeowners who are mad that they're cracking foundations, lifting up driveways, you know, causing problems in the street, um, breaking into sewer lines. But the reason live oaks tend to handle drought better than any other tree in Austin is because of the surface area that their roots cover. So they have so much more space to look for stuff and absorb um and find nutrients and fine little, you know, leaking irrigation lines or you know, little small pools of where water tends to collect than any other tree. And on top of that, they're great photosynthesis. So they make a lot of food and they make more food than they use, and then they store it in their roots. They have huge amounts of energy stored. So even when they run out of water, they can last longer than other trees. Um that really goes for the mature established ones. I mean, if you take a young one and plant it and it's only two years old, it's incredibly vulnerable to extreme drought, right? You you have to give those root systems time to develop. And the trade-off with a live oak is it's gonna take 75 to 100 years to have like a great root system. But when they do, that becomes a 400, 500-year-old tree. How big do they get in Texas? Oh, not as big as everywhere else. Um, I have seen them. I've seen them up to 40, 45, 50 inches in diameter. Um, so pretty big, right? I don't think I've ever seen a 70-foot live oak here, but they don't get tall, they get wide. So I've seen you know, live oaks that are maybe 40 feet tall, but then have an 80 foot spread, right? That's not out of the question. So they're they don't get too tall, but they just spread out. They're great shade trees. Better than a pecan, right? Just happiest trees that we have. Down here.
SPEAKER_01But you're cooler when you stand under a pecan, right?
SPEAKER_02That's what I think. For some reason. I think it's because they grow near water. You probably just have, you know, some evaporation and wind cooling you off.
SPEAKER_01With a sustained drought that you had for those four years, five years, whatever it might be, is there any other species that just it hasn't been able to make the comeback that it it's you're seeing more give up the ghost,
Trees that don't make a comeback
SPEAKER_01as we say, or do they do they hang in? Are there do they somehow hang in?
SPEAKER_02Well, no, there are some. So as far as like the big five trees in the Austin area, most of them can generally tolerate or figure out how to survive or decline a little bit and recover, other than maybe red oaks, right? But because we live in a a day where you can drive from Houston to Austin and under an afternoon, um, we have a lot of different trees that are coming from across the state and across the country that people are planting. And so trees that I grew up with, I grew up in Sugarland outside of Houston. And a tree that I grew up with and love is the Southern Magnolia, just another great swamp tree, and another tree that's better in Mississippi than it is in Texas. Um but people have brought them to Austin and they're great trees and they're beautiful, but they don't like droughts. They're swamp trees, and they don't have those aggressive roots that pecans have. So they will, when there's an extreme drought, you will see them have issues pretty darn quick. Um post oaks are another tree that also has issues. People have said they're drought tolerant. I will tell you, every post oak I've worked with has been such a finicky, uh, you know, vindictive tree. You know, the the joke is if you look at them wrong, they decline. And so I've seen them decline in drought, I've seen them decline in freezes, construction. I've seen them decline when everything seems to be going well for them. Um so they will have drought issues, at least in my experience. I don't know
Water restrictions and soil
SPEAKER_02how well documented that is.
SPEAKER_00Are there water restrictions there when things get dry, or can you water the trees?
SPEAKER_02Oh, okay. Oh no. It depends on where you live and depends on how many laws and ordinances you're willing to break. Um, but yes, it that's a big challenge here at the height of the summer, when the drought is at its worst peak, is also when the water restrictions roll up. And the water restrictions they aren't enough to sustain mature trees that are under stress. Um, so uh how do we beat that? The first thing we do is we try to never put ourselves in that situation. So we keep the trees well watered up until the water restrictions show up. We water as much as the city will let us. Um, some of my enterprising clients are like, I water more than that. I'm like, well, don't tell me. I can't I can't encourage you to break the law. But um changing soil conditions really helps. So there are things you can do to improve the health of the soil and the environment for the roots to grow in. Austin is a it's a part of the country where we don't have a lot of organic matter in our soil. We sit on a giant limestone rock. Um, and so you'll dig about two to three inches down and you'll get past all of that great organic matter, topsoil dirt. You just get to like mineral limestone. And that's a terrible place for roots to be. Um, so anything you can do to amend the soil with organic matter, compost, we use something called liquid humate. Um trying to add as much as you can is going to help regulate soil temperatures, encourage the roots to develop more, so get more of that surface area that we talked about with the live oaks. And you get a little bit more water retention in organic matter, right? Organic matter in the soil kind of acts like a sponge. Sandy minerals, they don't do anything. The water rolls right past them. But those you know, broken down leaves and grass and roots and bugs and whatever else you find in organic matter, those are what tends to hold the water. On top of that, mulching your trees helps. Um, mulch doesn't really do anything for your tree except for provide insulation to the soil below, so it it cuts down on the water loss rates from just heat and the sun. Um so doing that is gonna help. We have a product that is called phosphite that has also, for some reason, tended to encourage trees to store more energy and and activate parts or metabolic processes more related to survival and um and health rather than just growth like a nitrogen fertilizer would. So that also it tends to like cause the trees to store more energy in anticipation of something happening. So kind of coupling all those things is going to be a great way to help trees survive drought
Desert willow
SPEAKER_02in a place with water restrictions.
SPEAKER_01Before I let you go, what is the or is there an indestructible tree that laughs at drought down there? There's one.
SPEAKER_02It's called the desert willow. It doesn't get big, but I think it's an awesome tree. It's it's multi- it can be multi-stemmed. You can train it to do a couple of things, but think like an intermediate crate myrtle size plant, right? It's gonna get 15 feet tall if you're lucky. It's gonna spread out, it's gonna have a couple of different stems, but it's got these beautiful pink blooms. It's got the willowy feather-like leaf shape. Um, it's sparse, so don't plan it for privacy because you and your neighbors will be looking right through it at each other. Um, but it's an awesome tree, and I tell folks all the time it's the only tree in Austin that you could really overwater. Uh, but it it tends to not seem to care too much about drought. I've been water, I've got one for the record, I got one for free from Tree Folks, which is a cool company down here that um I don't think they're a company, they're a nonprofit, and they hand out uh free trees to people in the community to increase basically canopy coverage in the city. Um, and so I got one for free from them, put it in my front yard. It was uh smaller in diameter than a pencil last year when I planted it, and now it's about as big around as my thumb and four times taller. And I water it once a week if it's lucky.
SPEAKER_01That's so cool. Well, well,
Closing and how to reach us
SPEAKER_01that was so much fun. We covered a lot of ground there. It was great. One of these days I'm gonna see Austin. Uh I gotta get down there. And uh boy, I'm I'm looking, I'm gonna look up that desert willow, too. That sounds like a cool tree.
SPEAKER_02Well, just make sure you come down in the fall.
SPEAKER_01Yeah. When it's nice and cool, right? Yeah, yeah.
SPEAKER_02Maybe November. That's the perfect time for Texas.
SPEAKER_01All right, well, thanks again. Appreciate everything.
SPEAKER_02Alrighty, you take it easy, Doug.
SPEAKER_01Thanks for having me. You know what I want you to do? I want you to listen every Thursday to the Talking Trees podcast from the Davy Tree Expert Company. I am your host, Doug Oester, and do me a big favor, subscribe to the podcast so you'll never miss a show, and let us know what we should be talking about. You can send us an email to podcasts at Deby.com. That's P-O-D-C-A-S-T-S at D A B E Y.com. You can also click the link at the end of our show notes to text us a fan mail message. We would love to hear from you. And as always, we like to remind you on the Talking Trees podcast. Trees are the answer.