How This Year's Dual Cicada Emergence is Impacting Your Trees

Alec Hall, sales arborist from Davey's St. Louis West office, discusses the impact of this year's historical dual cicada emergence and how you can protect your trees if they were damaged. 

In this episode we cover:  

• St. Louis' cicada problem (0:33)
• 2024 dual cicada emergence (0:56) 
• The impact of the dual cicada emergence (1:47) (2:02)
• How do cicadas impact trees? (2:43)
• When do cicada eggs hatch? (3:58)
• How to treat trees with cicada damage (4:39)
• How smaller trees are impacted by cicada damage (7:00)
• Initial reaction to historical cicada emergence (7:57)
• Cicada predators (9:25)
• How to fertilize a tree damaged by cicadas (9:52) (11:16)
• How Alec got to Davey Tree (12:00)
• What Alec does in his role (13:06)
• How Alec feels being able to help others (14:04)

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

To learn more about cicadas, read our blogs, Do Cicadas Damage Or Eat Trees? and How To Protect Your Trees From The Periodical Cicadas in 2024.

To learn about other tree pests, listen to our Talking Trees episode, Spotted Lanternfly and Other Pests to Watch for. 

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. 

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

Transcript

Doug Oster: Welcome to the Davie Tree Expert Company's podcast, Talking Trees. I'm your host, Doug Oster. 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. This week, I'm joined by Alec Hall. He's a sales arborist in St. Louis for the Davie Tree Expert Company, and today, it's all about cicadas. Alec, I don't know anything about cicadas, so what's going on in St. Louis?

Alec Hall: Doug, just recently, and I don't know if you've heard about this or not, we had a dual emergence of the 17-year and 13-year brood, and it hasn't happened since 1803, so we're all learning at the same time about this. Did you hear about that in Pittsburgh?

Doug: I did hear about it, and I was wondering, I didn't even know that cicadas were something that was a bad thing for trees. I don't know anything about cicadas except we had some emerge a few years ago, and it was just like a loud event.

Alec: Sure, yes, I think that it's common for us all to experience periodical cicadas, particularly in August, but this year in particular, with the dual emergence that hasn't occurred since 1803, they really did have an impact on the trees, and I don't know if you guys experienced them in Pittsburgh or not, but in Missouri, it seems like there's been a coalition of cicada sympathizers that told us they weren't going to hurt our trees at all, and there's some good reasons for that, and we can get into that, but they have impacted our arboriculture quite significantly.

Doug: With this hatch or emerge, what do you call it, a hatch or emerge, or how do you call it?

Alec: We're going to refer to it as an emergence because they're emerging from the ground, and then molting into their adult cicada form.

Doug: Was it crazy when both of these types of cicadas emerged?

Alec: I tell you what, it was the-- Our Apple watches have decibel meters on them. If you have an Apple watch, you can turn that on, and it'll let how loud the environment is around you, and there are some areas in St. Louis where the decibels were above 90 decibels, which really requires ear protection, so it was incredibly loud, potentially hearing damaging in some areas, but for the most part, they're dying off now, so we're on the tail end of it, thankfully.

Doug: Some people said it would not negatively affect our trees, but you've seen that it was affecting your trees, is that right?

Alec: That's correct. Cicadas most technically, they don't feed on plant material, or at least they don't stifle the foliage of plants. The reason for this is they don't have mouthparts to do so, they're a sucking and piercing insect. What they do is instead of having sharp mouthparts, they have what we call a rostrum, or a beak, you could think of it like a beak almost, and they tend to suck the sap out of things, but that's not what's causing the damage. Everything's okay as far as their feeding, the issue is the adult females when they're laying their eggs into the branches of the trees.

The apparatus that's used is to deposit the eggs in the bark of the tree is like a saw, and it creates not only visual damage to the tree, but it destroys the vasculature beyond where those eggs are laid. What ends up happening is we get resulting breakages, and then the fluid translocation in the tree, it has quite a bit of trouble getting past where those eggs are laid.

Doug: When they lay the eggs in the tree, when do those eggs hatch?

Alec: It's going to vary by temperature, but the easiest answer would say it would be around six weeks, and that's not going to cause much damage. What will happen is when those eggs hatch, the cicada nymphs will fall down into the soil, and they'll burrow down into the ground, perhaps suck on some sap from the tree roots, which again won't because any damage, and then in which case they'll lay underneath the ground for 13 and 17 years respectively. Then we'll, that's that. They'll be underground for a long time.

Doug: Is there anything to do as far as treating the trees?

Alec: Nobody alive has ever experienced this, and in 1803, the last time when an emergence like this occurred, arboriculture wasn't really top of mind because we didn't have so many urban environments and people didn't invest so much necessarily in their greenscapes. We came up with some ideas, some people you'd see they were netting their plant material, trying to install nets around their trees to keep the cicadas off. The issue with that is obviously if you have a tree that's 10 feet tall, how are you going to net it? That wasn't necessarily efficacious.

Now there's been lots of talk about, and I hate to say it, but pesticides, but the truth is pesticides were largely ineffective. The reason, and we didn't use any, really nobody did, but the pesticides were largely ineffective because there were trillions of cicadas at once. If you put down something that kept them off your tree Tuesday morning at 8:00 a.m., they'd all be back by 10:00 a.m. anyways. The best thing that you can do at this point if you have a tree that is damaged, is simply to apply humates and fertilize. Just fertilize your tree. The mechanism of action in which those cicadas can harm a tree is by removing foliage. If you imagine a tree having an economy of resources, if you will, and we lose 10% of our foliage, let's say, due to the cicadas.

We've now stifled that tree's ability to photosynthesize throughout the year, fill its carbohydrate stores, and then do well throughout the winter so that it can emerge again in the spring. What will happen is that trees, they tend to not die overnight, but almost enter a decline spiral. Anything that you can do to increase the amount of canopy growth is going to be efficacious to you. Again, for the most part, larger trees are mostly ineffective because they can't remove so much foliage that they will negatively impact them. A ton of our urban landscape trees, that's where, our specimen trees, that's where we're getting a lot of calls. That's where we're going to have a lot of trees that need replaced this year.

Doug: They are, some of those trees are taking a beating and you will be replanting in the fall.

Alec: Some of the smaller trees, and I don't know what ornamentals you guys have up in Pittsburgh, but our state tree is a dogwood, probably heard of it. The flowering dogwood trees in particular, they're pretty well damaged. I know in the past few weeks, a large part of what we do is disease diagnosis and treatment. I've been getting a ton of calls where people think that their dogwood tree has some type of nefarious fungal infection, which things like that do exist. Nine times out of 10 right now, it's really just the cicada damage. All we can do is show people that and tell them, "Hey, we're right here with you. We don't really have a great answer for it. Let's just fertilize. If it doesn't make it in the fall, then we can always swap it out for you."

Doug: When you heard that both of these different types of cicadas were going to emerge, were you like, "Oh man, this is going to be crazy?" Was it just like, "Since we've never seen it before, [inaudible 00:08:11] was like, we don't know what to expect."

Alec: For me, I'm going to be honest, I was a bit laissez-faire about the whole deal. I don't have a background necessarily in entomology. The cicada thing, we all know what cicadas are, and you'll learn a bit about them through education, but after they started laying their eggs roughly two weeks ago, it's just been an immense amount of damage. It's an understatement to say that it's not having a huge impact on landscape trees.

Doug: What happens to the adult after it lays its eggs?

Alec: It dies. The adults, there's corpses everywhere. They're all over our yard. Again, they do provide some benefits. When they emerge from the ground, it looks like you ran an aerator over the yard almost. There's so many holes in the turf, which I suppose, for [unintelligible 00:09:12] strings that might serve some good purpose. Likewise, when they degrade in the yard, that's only going to aid in adding back nitrogen, potassium, phosphorus to the soil as the material decays.

Doug: Are there predators when they're out laying their eggs and stuff? Do birds eat them?

Alec: Yes, birds will consume them. Another problem is people's, their pets consume them, and they tend to get sick because they'll eat so many of them. They're not poisonous, but they're such a feast to be had that it seems to be the case that a lot of my client's dogs have been getting sick by eating them, yes.

Doug: Talk a little bit about the fertilization process. What would be the best way, let's say, you were in an area that had this problem and you saw your tree was struggling a little bit, tell me how you fertilize it.

Alec: Yes, sure. First I'd ask you, do you have any background in chemistry?

Doug: Me? Absolutely not.

Alec: Okay, good. Then you can't beat me up too bad on this explanation. This time of year, we prefer to, although you can any time of year, we prefer to hold off on fertilization until the fall. It's not that you can't do it now, but when we have such an impact to the trees, there's better things that we can do now than just add fertilizer. If you've ever heard of humates or polyphosphate in agriculture, polyphosphate's been used for 60 years and it's really just now being introduced into arboriculture. This time of year, we like to add humates and polyphosphate. What that does, if you're familiar with terms like chelation or cation exchange, it just allows for more of those minerals to be systemically taken up by the tree. It's almost like we're preparing soil today so that we can really get the best bang for our buck or the best value for our money with fertilizer later on in the fall. It's all applied hydraulically and it has a really big impact.

Doug: That was another part of the question that I was wondering about, was with the heat, I'm assuming you wouldn't want to fertilize, but how are you putting the humates and that other stuff into-- Is it just injected into the soil like the fertilizer?

Alec: Exactly, yes. If you're familiar with how arborists put fertilizer into the ground, it's a similar process where it's going to be injected into the root system, well, not directly into the roots, but injected into the soil surrounding the roots of the tree.Ssame system there. I will back up and say, not necessarily. You can fertilize now with the right product and not harm your tree. If you ever do want to fertilize in the summer, there's solutions for that as well.

Doug: Okay. Tell me a little bit about how you got into this. What was your journey to end up at Davey?

Alec: Yes, well, my journey, I've been here 12 years. I started here when I was just turning 21 is when I started here. I was in college and needed a summer job and I never left. Truthfully, my background it's not actually in forestry specifically. In the St. Louis area, we tend to get a lot of our forestry grads out of SIU Carbondale because they have a big forestry program not but two hours away from us. We do a lot of recruiting out of there. I went to St. Louis University, which is in St. Louis, obviously. They did not have a forestry program. Even after I was done with my college journey, I just didn't want to leave. I stayed around and started mowing lawns and then climbing trees. Then Davey sent me to Kent, Ohio, and got me some more education. Here I am now just consulting with people.

Doug: Tell me a little bit about that. Tell me a little bit about your job, being out in the field, and helping people with their trees.

Alec: Sure. Day to day, it varies so much, which I think is the reason I like it. There's a lot of a lot of mental freedom to practice with the backing of science with the way you think is best. My calls, they range from, disease diagnosis and treatment, sampling tissues of different trees to send up to our lab, all the way down to Mrs. Smith wanting her apple tree cut down and just needing a bid, which is those are always the easy stops, but they're not quite as fun when we get to play detective, I have a ton of pride in it.

I love what I do. I love the science part of it. The investigation aspect, just solving problems. The trees don't have anybody to speak for them, but we can.

Doug: That's great. When you do play detective and you figure things out, and people are often thinking the worst when you can tell them, "Hey, it's going to make it." Tell me about that feeling. I ask that to arborists a lot.

Alec: Yes, well, that feeling's always good. The problem is they don't normally believe you until you're a couple of years down the road. The best feeling is when somebody's real concerned with a tree and we say, "Hey, I think this is a good candidate for preservation," and they say, "Well, I don't know, Alec. I'm not sure if I want to invest in that." I say, "Well, I think it's a good candidate." Then they follow the protocol and we can go back three years later and they say, "Man, I thought that was a waste of my time and resources, but it looks great now and that's fantastic."

Most of the time, if we can identify a cause, then we're on the right track. Even if we can't, people don't understand always that in an urban environment, it is sacrosanct to be fertilizing, humating your trees, and creating a good soil profile so that they can live. Urban spots, they're not natural spots for trees. In the woods, it's different. Urban trees need help, a lot of help.

Doug: Alec, I'm going to leave it right there. I want to thank you so much for taking time away from your vacation. Tell everybody where you're at to do this interview.

Alec: I'm sitting in a quiet, I don't know, quiet bathroom here in Hilton Head, South Carolina because there's a bunch of kids running around the house. I heard that we might get to do an interview on cicadas and I said, "Well, I'm not going to pass that up."

Doug: I appreciate it. You go out and get some beach time now.

Alec: All right. Time to go fishing. I appreciate you, Doug.

Doug: All right. Thanks so much.

Alec: All right, man. Bye now.

Doug: Can you imagine the sound of all those cicadas and needing ear protection? Good stuff from Alec this week. Tune in every Thursday to the Talking Trees podcast from the Davie Tree Expert Company. I'm your host, Doug Oster. Do me a big favor, hey, subscribe to the podcast so you'll never miss a show. If you've got an idea for an episode, maybe a comment, send us an email to podcasts@davie.com, that's P-O-D-C-A-S-T-S at D-A-V-E-Y.com. As always, we'd like to remind you on the Talking Trees podcast, trees are the answer.

[00:16:43] [END OF AUDIO]