Spotted Lanternfly and Other Pests to Watch for

Mike Holleran from Davey's Wilmington, Delaware, office talks about spotted lanternfly (SLF) and other pests affecting his office and how they can best be treated. 

In this episode we cover:  

• Spotted lanternfly (SLF) (0:40)
• When SLF reached Delaware (1:36)
• SLF damage (2:22) 
• Tree of Heaven (3:27)
• SLF treatment (4:57) (6:47)
• How long SLF was a major pest in Delaware (6:00)
• SLF peak (8:28)
• Emerald ash borer (EAB) (9:39)
• Crape myrtle bark scale (10:15)
• Tree and shrub maintenance (11:50)
• Least toxic tree care approach and insect growth regulators (12:26)
• Beech leaf disease (BLD) and how it's treated (15:04)
• Michael's stories from the forest (18:11)

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

To learn more about SLF, EAB, BLD, crape myrtle bark scale and other pests and diseases, visit our Insect & Disease Issues blog page. 

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

[music]

Doug Oster: Welcome to the Davey 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. My guest this week is Mike Holleran. He's an assistant district manager for the Davey Tree Expert Company in Wilmington, Delaware, called Wilmington Brandywine Office. Today we're talking all about pests. Mike, welcome to the show.

Mike Holleran: Thanks for having me, Doug. Always a pleasure.

Doug: Well, I want to pick your brain right off the bat because we are into season two of spotted lanternfly and people are going nuts. I've talked about this before, Mike. What I found interesting was we had emerald ash borer come through. It didn't get nearly the attention that spotted lanternfly has got, I guess because you can see the spotted lanternfly. [chuckles]

Mike: Yes, 100%. Spotted lanternfly is very in your face. It is very visible. It affects multiple species of trees. Where emerald ash borer, you may not notice you have it. It's only really going after ash trees. Frankly, a lot of folks don't know the species of trees they have. I think we talked about that last time, having an arborist out to just identify species would have helped with emerald ash borer. With Spotted lanternfly, it is very in your face. You can't miss it if you have it.

Doug: When did it come into your area?

Mike: In Delaware, we probably started to see it four years ago now, three or four years ago. It went through like an absolute tidal wave, man. It was really bad. It was very visible. The phones were ringing off the hook. People were panicked. Frankly, it was new for us. This is a relatively new pest. We didn't really know the extent of the damage or the extent of the species that it was going to affect. It was sort of learn as we went.

Doug: That first infestation that we just went through, like I said, I understand that phone's ringing off the hook. What was the damage? How bad was the damage those first couple seasons?

Mike: Tree of Heaven, which Spotted lanternfly really likes, would be heavily infested. We did see some damage there. Mostly Spotted lanternfly, in my opinion, is a nuisance pest. It is, again, very visible, very in your face, creates a lot of mess. As they feed, their excrement is sweet and sticky, so it falls all over driveways, cars, houses, play sets. Then, it grows sooty mold. You have this black, sooty material all over anything that it is feeding above. Spotted lanternfly, big nuisance pest, but honestly, the damage to trees around here was relatively low.

The further we got into it, the more we were recommending those treatments for very high value trees or trees that were very close to a structure, a driveway, a play set, things that you didn't want mess on.

Doug: With the tree of heaven, we don't care about the tree of heaven. My tree of heaven was infested and that was fine with me. Go after the tree of heaven, stay away from my maples, stay away from my grapes, stay away from anything else you might feed on. I had people calling me saying, "Hey, I want you to come out and identify tree of heaven so I can get rid of it because I don't want the spotted lanternfly," and I said no. I said, "They prefer that tree. If that's not there, they're still going to be there." They're going to find something else to feed on, right?

Mike: Right. We used tree of heaven in a number of different ways. Like you said, tree of heaven is not a very desirable species. When we first heard of lanternfly and its preference for tree of heaven, and we weren't sure that it was going to go to other species, it was like, "Have at it, man." If it was going to be like emerald ash borer, have at it. The problem is it does affect a number of different species, so it's not tree of heaven specific.

There were a number of ways we used tree of heaven to our advantage. We used them as bait trees. We know that that spotted lanternfly is drawn heavily to that species, so there's the potential to treat it with an insecticide and use it as bait.

Doug: Yes, and so let's say I had got a maple tree over my deck and the spotted lanternfly gets on there, starts feeding, that honeydew, or whatever you call it, and then sooty mold is so disgusting. What is the treatment? What can you do for a tree to stop that spotted lanternfly?

Mike: There's systemic insecticides that we can use. Obviously, we need to be mindful of pollinators and how trees are pollinated. I would be leery of using some of the systemic insecticides on some of the bee-pollinated trees. A lot of what we do, we can't spray a huge 90 or 100-foot maple that's right over your house. A lot of times in my area, the yards are not huge, so we run the risk of chemically trespassing if we try and spray a big tree. Really going after it systemically.

We can go through the roots, we can go through the bark with a basal bark spray, and when the lanternfly land on the tree and start to feed, they ingest that insecticide and then die. You will still have mess, because as those lanternflies die, then they are falling out of the tree, [laughs] but you're doing your part for sure.

Doug: How long was the spotted lanternfly a major pest in your area?

Mike: Major was probably three or four years. I still get calls every once in a while. I still have a unmaintained area in my backyard where there's some wild grape growing, and I will see the nymphs on the wild grape still to this day. The first three years were really the worst. I think year two, unfortunately for you, was the worst of the three. It seemed to ramp up in year one, and then year two was really our worst infestation. Year three, they were still around, but maybe not as many as year two. That was pretty hard to quantify, though. Then, just a steady decline after that.

Doug: Let's talk about dealing with those pests the right way instead of making some kind of homemade recipe. When something like this comes through, I start seeing all this stuff online, which could be possibly dangerous to other wildlife, to your family. Stick with what we know as far as science is concerned when dealing with this pest, right?

Mike: Absolutely, and hire a licensed applicator to put it on there. When you're dealing with pesticides, you should always have a licensed applicator doing it. We know the way that these things work. We are mindful of their impact on pollinators and other off-target species of insects. Yes, certainly there are some things that I am all for homeowners trying on their own. If you have a small infestation of aphids on a little perennial, certainly mix up your insecticidal soap and go for it, but when we're talking about treating with a systemic insecticide, I always say hire a pro for that one.

Doug: Yes, and then we've seen also sticky tape put around a tree that's catching all sorts of other pollinators and possibly birds. Again, stick with the pros. [chuckles]

Mike: Stick with the pros. I mean, we've seen that come through here too. Frankly, you can drive around my town and still see tape stuck to trees to try and catch the lanternfly nymphs. I'll be honest with you, that tape works a lot better on the nymphs because they aren't flying. The nymphs are crawling and they get attached to that tape and it does a pretty good job, but you're right, that tape, it doesn't discriminate. Anything that crawls over it is stuck.

Doug: Do we know why the spotted lanternfly has this peak at the beginning and then fades away? Is it nature making a balance or do we know?

Mike: We don't really know. I've seen more predators around here, birds and things starting to pick them up. I think some of that has to do with their coloring. A lot of times in nature, things with red or orange or very bright colors, they're for a warning, and I think that the birds and the other predators know that. It's there as a warning, and I think they were leery at first, but now I do see more birds eating them. I saw that year three, it started.

I saw a cool picture of a spotted lanternfly in the grasps of a praying mantis a couple of years ago, which was really cool to see. Yes, it seems to be like a wave coming through. At the front end of their spread, the infestation is pretty bad.

Doug: Yes, I know. It's panic mode here as soon as those nymphs start, but we'll try and keep everything, "Calm down. Okay, it's all right. Keep your tree of heaven." Now, in your area, what is the next pest that you're starting to think about this time of the year that might be problematic?

Mike: We deal with a litany of different issues for different species. Obviously, emerald ash borer is still big on our list, protecting high value ash trees, and that is absolutely doable. It is a shame that more people didn't realize they had ash trees, take advantage of a free arborist consultation to get the species on your property identified so that we could have done more in that arena. Dealing with crape myrtle bark scale, that's sort of moving up from the south for us. It's in lower Delaware now, down by the beaches.

I'm as far north in Delaware as you can go, and I haven't spotted it here yet. Crape myrtles are very, I tend to say almost over-planted by me. In this area, 10 years ago, they were utilized every once in a while, but people love the summer flowers. They love the fact that they're easy to grow. They're in almost every yard. When you get that scenario and a pest that affects that species comes into play, you really run the risk of some significant damage.

Doug: Yes, I don't know the pest, but whenever I hear the word scale, that scares me.

Mike: Yes, and we deal with prunicola scale on laurels all the time. Laurels is another plant that I think is over-utilized in our areas. There's a lot of native alternatives that I think are better. Cherry laurels, for instance, and people always have the tendency to shear these cherry laurels into like ball, which they don't want to be, and that makes the environment for that scale insect even better. They just thrive in those conditions. I think taking a holistic approach to plant health is the best way to do it.

Not just triaging a insect problem, but really limiting the stress of the plant, doing proper pruning techniques, all the things to take care of that plant as a whole.

Doug: We're talking watering, we're talking fertilization, we're talking proper pruning. Doesn't it drive you nuts when you see those plants turned into meatballs? [laughs]

Mike: Bananas. It drives me absolutely bananas. I think we plant something, at least I plant something in my yard because I like it, I like the way it grows. I think plants being unique is what makes them interesting. If everything looks the same, they are far less interesting. When everybody has their shrub shaped into these little round balls, not only is it detrimental for the plant, but it is far less interesting for the landscape.

Doug: You touched on this earlier, but talk a little bit about using the least toxic approach to dealing with basically what you said, triaging the plant if it gets infested with an insect. You mentioned insecticidal soap, maybe horticultural oil if possible. Certainly you don't want to have chemical drift to some other yard.

Mike: Right. That's an approach we take on a very regular basis, especially with scale insects, for instance. if we come up on a laurel with a very heavy scale infestation, we may need to triage that with a systemic insecticide to get it under control a bit. We know that those scale are probably going to return at some point unless they make some cultural shifts in the way that cherry laurel is maintained. Once we initially hit it with that systemic insecticide and knock a lot of them back, we can typically pivot into something a little less toxic. Like you said, the horticultural oils.

Insect growth regulators are a great tool for us. We always think of tree growth regulators, but we also use insect growth regulators that stop that maturity of the insect. If they never get to an adult, it can't reproduce. Those things are much more friendly to us as applicators and to the environment as a whole.

Doug: Well, I've never heard of that before, the growth regulator for an insect. That's really fascinating. Tell me a little bit about that. How long has that been in play? Has that been in play for a long time?

Mike: Yes, we've been using it for the last few years in my area. We use it a lot for scale. Scale is a really challenging one sometimes. Prunicola scale can have multiple generations in a year, so trying to really get control there is tricky. Those insect growth regulators, they're nice because they are significantly less toxic, again, to us and to the off-target insects, but they also work really well as long as you time them right. Timing is key with a lot of these pest applications.

I think overall we've been, how do I say, we've been lucky. Being able to use systemic insecticides takes a lot of the guesswork out because they have that really long window of efficacy. You don't need to be quite as specific with your application timing. When you can be specific and use the tools we have, like growing degree day monitoring to see when these insects are at target application time, we can really use something significantly less toxic and easier on the environment.

Doug: How about something else on the pest list that is problematic for you?

Mike: A huge one for us, and this is spread by a pest, but the actual disease is beech leaf disease. Beech leaf disease is very concerning to me specifically. It's spread by a foliar feeding nematode. There's really no good way to control the insect. We are focusing our efforts on managing the plant stress and using humates and phosphonates and things like that to try and help the beech trees along. I bought the house I grew up in for my parents. The woods behind my house, I used to play in as a kid.

My two boys are back there in the woods playing now in the same spot that I was when I was their age. Those woods are probably 60% beech. If the beech leaf disease really does the damage that we know it can, that would change my landscape. It would change my landscape significantly. There's a big population of beech around here.

Doug: Tell me a little bit about the pest and then we'll go into the disease, because I have touched on the disease with other arborists, but what makes the pest so difficult to control?

Mike: Number one, beech trees are pretty big. Again, we go back to that spraying and the chemical trespass and the drift. It makes it very difficult to spray a large beech tree. Plus when the insect or when the nematode feeds, it's vectoring that disease. If you were to do a systemic insecticide like we do with emerald ash borer, if there was the potential for that, the way that works is the systemic insecticide is in the tree system. The insect or nematode needs to bite into that to ingest that insecticide.

Well, once it bites in, it's already vectored that pathogen in there. It's a very challenging one to control from that perspective.

Doug: How are you treating the tree? You've touched on a little bit, but what's the best way to deal with these trees? Those trees for you, those are very important trees.

Mike: They are. In a suburban or urban landscape, we're going in and recommending a three-step fertilization process. We're using phosphonates as trunk sprays. We've seen a lot of results there, but in a wooded setting, phosphonate trunk sprays work pretty well, but it's all about limiting the stress of the tree and trying to avoid the draw of that tree for this pest. The problem is, again, sort of like spotted lanternfly, this is relatively new for us, so we don't have a really long history of results with these treatments.

We're working through it, coming up with some best practices. I know some other tree companies in the industry are doing the same in a different avenue, and we're all coming up with the best way to deal with this. Certainly don't want to lose all the beech trees.

Doug: Well, that's where I want to go right now. I just wondered when I hear about that forest that you grew up in, are there stories you tell your boys about your life running around in the forest?

Mike: I do. It's funny. We were back there walking around. There's a little creek back there that we walked down to, and I remember vividly when I was a kid, me and my buddies would be out riding bikes, and we wanted to build a bike jump in the woods. One of the dads brought out some landscape timbers, and we hammered this thing together, and we made ourselves a little bike jump. Well, I'm walking around with my boys the other day, and here is this standing landscape timber wall, still there from when I made it when I was a kid.

All the dirt around it has since eroded, but the landscape timber wall is still standing there. It's nice to see those things. I'm sure you could find my initials carved into one of the beech trees back there somewhere. I don't exactly remember where.

Doug: That's my next question. Is there a little heart there with your initials?

Mike: I'm sure, but that was pre-wife, so I probably don't want to take her to show her those initials, but yes.

Doug: Well, one more question about that forest. Tell me a little bit about how it makes you feel to see your boys running around in that forest that you were running around in when you were a little kid.

Mike: Yes, I love it. I didn't know the joy I would have until I had kids and it actually happened. What's different for me is, like I said, when I was a kid, we were out there riding around on a bike. Everybody was outside playing. That's not how it is anymore. It's far less likely to see everybody outside playing in the woods. Everybody's got the screen in front of them. We try and limit the screen time for my kids as much as possible because I think it's very important to be out in nature, explore, find bugs, turn over rocks, do the things that we are meant to do.

That's something I pride myself in. We spend as much time in nature as we possibly can.

Doug: Well, I'm going to leave it right there, Mike. That's great. Although you are starting to sound like an old man like me, but that's okay.

Mike: Yes, I'm getting there. I'm getting there, Doug.

[music]

Doug: All right, Mike. Thanks so much for your time today. Great information. Really appreciate it. Thanks for sharing your stories about the forest.

Mike: Appreciate it, Doug. Look forward to doing it again.

Doug: I hope you enjoyed that as much as I did. That forest behind Mike's house where he had all those special times will now be making memories for the next generation. I think that's awesome. Now, tune in every Thursday to the Talking Trees podcast from the Davey Tree Expert Company. I am your host, Doug Oster. Do me a big favor, subscribe to the podcast so you'll never miss a show like this one. Do you have an idea for an episode, maybe a comment? Send us an email to podcasts@daveytree.com. That's P-O-D-C-A-S-T-S, at, D-A-V-E-Y, dot com.

As always, we like to remind you on the Talking Trees podcast, just like those woods behind Mike's house, trees are the answer.

[00:21:24] [END OF AUDIO]