Talking Trees with Davey Tree

How to Prevent Spring Pests Early

March 16, 2023 The Davey Tree Expert Company Season 3 Episode 11
Talking Trees with Davey Tree
How to Prevent Spring Pests Early
Show Notes Transcript

Natascha Batchelor of Hartney Greymont, a Davey company, talks about spring pest prevention, volcano mulch and unique trees. 

In this episode we cover:  

  • The first thing Natascha thinks about when looking at trees in spring (0:52) 
  • How Natascha decides when to use horticultural oil (1:32) 
  • Dealing with scale (2:49) 
  • Fertilization for pest prevention (3:51) 
  • What the soil is like in Cape Cod (4:46) 
  • What to do about planting in poor soil (5:24) 
  • What is Biochar? (6:36) 
  • How an air spade works (8:10)  
  • What needs to be done for sandy soil (10:48) 
  • Liquid fertilizer (12:05) 
  • When looking at a tree, how does Natascha decide what to use? (12:42) 
  • How a root flare becomes covered (14:50) 
  • What to anticipate with pest problems and preventative work (17:36) 
  • Unique trees Natascha recommends (19:55)  

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

To learn more about tree scale, read our blog, How to Manage Scale: Early Prevention is Key

To learn more about keeping soil healthy, read our blog, How to Keep Soil Healthy for Your Plants. 

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

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

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. This week, another return guest. Natascha Batchelor is a sales arborist for Hartney Greymont, a Davey company. Today we're going to talk all about a little spring prep and maybe some pests too. How are you doing, Natasha?

Natascha Batchelor: I'm doing great today. How about you?

Doug: It's windy in Cape Cod, right?

Natascha: Yes, that's the daily for us.

Doug: First off, we're talking about spring. That's a positive right there. We're finally getting out of winter. What's the first thing you think about when you're looking at your trees for the first part of the season here?

Natascha: Going into the spring, we typically concentrate on overwintering pests because we can apply horticultural oils for certain pests to smother the insects, so overwintering mites, sometimes wintering eggs of certain insects. We used to have populations of something called winter moth here, which horticultural oil could help a little bit smothering some of the eggs. It's really eggs and overwintering nymphal stages and things like that.

Doug: Is it specific trees that get this treatment because certain insects are on the trees or do all trees get it? How do you decide where you're going to put horticultural oil?

Natascha: Typically, the ones that we're going to be able to target with the horticultural oils are going to be pests and they're typically scales and mites. They're going to be on evergreens. A lot of evergreens have that issue. There are some other plants that can have some overwintering eggs as well. It's a case-by-case basis.

Doug: Do you have hemlock woolly adelgid up there?

Natascha: Don't we all?


Doug: Sadly, we do. I've got tons of hemlocks on my property and that's how I'm trying to deal with them. We had a real killer cold snap at Christmas, which always knocks back the hemlock woolly adelgid. As soon as I see them, I'm spraying with horticulture oil. Am I waiting too long?

Natascha: No, no, you're not waiting too long. Spring oils are fine for that. You can get good control for quite a few months in the spring. The trick with horticultural oils is we don't want to spray too late because you can cause damage to the plants if it gets too warm.

Doug: Tell me a little bit about scale because when I think of scale in general, I think it is a very difficult pest to deal with on indoor plants. Is it the same on outdoor plants?

Natascha: It really is. Since we're talking about hemlocks, we have a lot of hemlock, elongate scale here. My experience with that is it's pretty difficult to control with oils because, again, with the scales, they have a waxy coating on them and you really have to get good coverage, and timing on scales can be problematic. Sometimes you need to get them in the crawler stage, which could just be a couple of days because they start to form that waxy coating pretty quickly.

Doug: Timing is everything. If it's only a couple of days, that's tough to schedule.

Natascha: It is a challenge. The key to managing a lot of pests is the overall health of the plant. They're going to be able to kick in their natural defenses if we can keep them healthy.

Doug: That leads me to fertilization. Is that what we're talking about?

Natascha: Yes. Fertilization is one part. As things always are changing in our industry as we learn more, a lot of research has been going on in the past or being published in the past maybe decade or so about soil health. That's everything from the organic matter in the soil to the nutrient management, which the fertilizer help deal with one component of that. A lot of it is what kind of soil do you have? I think we discussed it last time, but I have clay soils here, which I didn't expect on Cape Cod. There are some seams of clay. That makes it really difficult for nutrient availability for plants because, on clay soils, the nutrients bind really closely to the particles.

Doug: What is the soil like there then? Because when you said clay, I was just going to say, "Don't we all have that?" Because that's what we have down here in Pittsburgh.

Natascha: A lot of the soils, especially as we get down towards the end of the world, Provincetown, the tip of the Cape, it gets very, very sandy. We have problems with-- it's the opposite, the nutrients just fall right through the soil. There's nothing for them to hold onto. We try to supplement both types of soil with organic matter to try to increase its ability to make nutrients available to the plants.

Doug: Let's talk about that. Let's say we find a spot, the right tree for the right place, but the soil is either that clay or it's real sandy. What do we do? What do we do when we plant? In general, I've heard not to amend the soil for trees, but you can't put a tree in pure clay. We know that's going to be a disaster.

Natascha: Yes, exactly. With the clay, organic matter, and we're looking at trying to change the texture of the soil. Some ways that we manage that is newer products called biochar which is a supplement to the soil. It can be amended and put in different ways depending on the situation. It can come in large chunks when you have a really difficult clay area, it can come in rice-size chunks. It can come in particle-size chunks depending on exactly what kind of soil and the situation that can be added into the soil to help with that exchange capacity for the nutrients.

Doug: Schoolman biochar, and we might've talked about this before, I hear it mentioned all the time in all positive references, but I just don't know anything about it. We dig our planting hole. Let's just go with clay. We dig our planting hole. It's got some decent soil in there. Tell me about the biochar, what it is, and how you apply it.

Natascha: If you're doing it at planting, it's mixed in with the soil that you're putting back into the hole. That would probably be the rice-sized. They come in bags and it has different sizes, basically how small it's been chunked down to. The rice size would be mixed back in with it. If you're dealing with more established plants, then we're looking at mixing it in with air spades or putting holes in, vertical mulching to apply it, but that's usually done with an air spray. That material, what it is, it's basically wood that has been baked more than burned. When you think about when you have a fire pit, you end up with a pile of ash at the end. The process that they use leaves the cell structure intact. It provides space and pores for the soil nutrients to adhere to.

Doug: I want to talk about the air spade. That would be an instance, like you said, a tree's already there. We know it's growing in poor soil. We can see it's growing in poor soil. Explain how the air spade works. Here's my guess, then you correct me. You're using it to get a hole down into the root zone. Is that right or is that wrong?

Natascha: Yes, so for vertical mulching, what's happening is we're taking the air spade and the air spade is highly compressed air. We're making a hole by blowing the soil out. That allows us to put the materials directly into the soil. In a large mature tree, you're not going to dig it up and change the soils. It provides an opportunity to mix that material into the soil. The nice thing about the air spade is it doesn't kill the roots. It doesn't break the roots apart. We're able to get into the ground without severing the roots.

You might get some fine feeder roots that blow out, but the main root structures, it stays intact without any damage. Then we're able to just basically funnel it into that hole if we're doing vertical mulching. Alternatively, this vertical, I might get the name wrong, but we're we're blowing out sections of the soil in the radius of the tree and then mixing the materials in with the air spade like stirring your mixture for baking a pie or baking a cake. You're mixing all the ingredients together. We're stirring it up with the air spade with those amendments in.

Doug: When you're using an air spade in general, how deep does it go to do that type of work?

Natascha: If it's not too compacted or if you don't have too intensive clay, you can usually get at least12 inches down, and that's where a good portion of your root system is. If it's harder compaction or it's really intense clay, you've got to use basically a larger air compressor to get that pressure.

Doug: [00:10:17] The biochar doesn't provide nutrients, it's just providing space so that we can get nutrients into it. Do I have that right?

Natascha: Exactly. It's providing pores space for those nutrients to attach to the surfaces to be available for the plants and also for air and for water.

Doug: Where would you use the bigger chunks of biochar?

Natascha: The bigger chunks can be helpful in the vertical mulching, just it's sometimes easier to put them into the holes that you've created with the air spade.

Doug: For sandy soil, what do you do there? If it's super sandy and you're going to put a tree in, what needs to be done in that planting area?

Natascha: In those cases, we're adding organic matter. Usually, once some aged organic matter, often aged manure is a good one to use. Obviously, you don't want a 100%, so you're mixing it back in with the sandy soil.

Doug: I've been told, again that if you were to dig a planting hole, and if you do amend it, those roots will stay in there. What are you doing to make them spread out? Is it just the mixture of that organic matter and bigger holes or--?

Natascha: I would say bigger holes is the way to go. If the soil types are that different, ideally you're mixing some of the original material with your amendments.

Doug: In bigger hole, that to me says I need a pro because I don't want to dig a bigger hole. What about the fertilization that we've talked about with this arborist before with like it's a probe or something you put in? You put in a liquid fertilizer. Is that a spring thing or is that later in the season?

Natascha: Spring's a good time to do it. It can be done in the fall. It can really be done anytime during the growing season, as long as you're using a slow release. We use a suspension in water, so it actually needs microbial activity to break it down. If you do it in the summer, it's not going to go anywhere until the soil temperatures are at the ideal conditions for microbial action.

Doug: Talk a little bit about when you look at a tree, how you-- I know this is a really open-end question, but how do you know, when you're looking at it that it's going to be an air spade with biochar or a liquid fertilizer probe or both? How are you making these decisions?

Natascha: This usually confuses my clients, but when I show up on a tree, property to look at a tree, I give a glance at the crown just looking for overall health: are the buds good, are the leaves good, is there dieback, and that kind of thing. I go right onto my knees, right down to the root flare where the tree meets the soil. Probably 75% of my properties, that's the first place I'm going. I'll take a chaining pin and a soil probe. The chaining pin, it just has measurements on it.

It's a narrow pin, and I try to determine where the roots are. We often have trees that the root flare is missing, so I'm trying to look to see where that is. If the root flare is buried, then I'm thinking air spade, because we got to get that soil away from that root flare so that we don't get girdling roots that can promote rot at the base of the tree, which is obviously not good for the tree. That immediately calls for an air spade. Then the soil probe, I use to get a feel for what the soil looks like.

Is it a nice sandy soil? Is it a nice loam? Is it light mine where I have 42 inches of clay? Though my probe doesn't go down that far. I did some special testing on that. Based on what the soil looks like, that's when we're going to start thinking about other options. Then if it's an unusual soil, we're thinking about soil tests. Sending it off to a lab to determine texture and what nutrients are available to the plants in that soil.

Doug: From talking to arborists, I know how bad it is to have that root flare covered. Is that usually from improper planting or does it happen over time?

Natascha: It's usually from a combination of improper planting and overzealous mulching. I want to be nice about that. It's overzealous mulching. Sometimes people throw extra soil on thinking that that's going to be their best bet in order to plant other things around and that can cause problems later down the line.

Doug: AKA volcano mulching. Doesn't it drive you nuts?

Natascha: It does. I think they're starting to learn. I get more questions from people, "Is my mulch too high?" rather than having to point it out to them that they're starting to understand that they need to pay attention to that.

Doug: Natasha, my own son sent me a picture when he moved into his house a couple of years ago, what he was doing on his huge Japanese maple, and I just about had a heart attack. I need you to come down with the air spade right away. [laughter]

Natascha: I had a client who had probably about two and a half feet of mulch against their trunks. I was like, "This is too high." She was like, "Are you kidding me? I just had that done a week ago. " [laughter]

Doug: I tell this story all the time. The Davey guys here in Pittsburgh, they come on my radio show. Davey used to take care of this complex across the road from us, and some new manager of the property took over and ordered Davey to do volcano mulching. Of course, they said, ethically, you can't. Every time I pull out of there, I am not kidding you, these big giant oaks have at least six feet of volcano mulching on there and they just keep going up and up and up. We talk a lot about volcano mulching on the podcast. Every time I drive out, I just shake my head and I feel so sorry for the tree to tell you the truth. You know how we have this affection for trees, and to see that just because somebody doesn't know any better, but they've been told better, but they think they know better.

Natascha: Unfortunately, we can't get to everyone.

Doug: It's my mission to get to everybody. We've gone down a different path than spring pasts, but good stuff. What else were you thinking about talking about when we're talking about spring? Was there something else that we missed?

Natascha: Yes. It’s important for people to know what they have so they know what they can anticipate for pest problems. One of the things I run into in late spring is people start to see issues with their leaves on their trees. They've got spots, they've got scabs. They look brown or wilted. A lot of times they're dealing with fungal issues. The important thing to understand on that is those are treated generally preventatively. Understanding that you have maybe a crab apple that's more prone to apple scab, we've got to get in there and get them a program to preventatively try and manage that. It's got to start right as the leaves start to emerge. If we are looking at them once the leaves are fully out, we're not going to be able to treat for that particular disease issue. It's already occurred.

Doug: I was definitely going to go with crab apple as soon as you said fungal diseases. If you've got a crab apple that every year drops its leaves, gets apple scab, it just makes perfect sense to treat before you see signs of damage. I think that's a hard concept for many homeowners to understand. Usually, it's the reverse. You wait until you see something chewing your leaves or something, then you treat it. For fungal issues, getting to it early is important, right?

Natascha: Exactly. Get an arborist out there to provide a care plan for your property early, early spring before things really start to leaf out. That's the key.

Doug: Before things get crazy busy.

Natascha: This is true.

Doug: Before we get into the summer storm season and all that stuff, have an arborist out early. I have an arborist on my property at least twice a year because I'm in a declining oak forest and I talk about it all the time, and every time I lose an oak, I try and put something in that's kind of cool, something different. My arborist always has some cool and different thing I can put in. Natasha, that's where I'm going to put you on the spot. We repeat this mantra over and over again, right tree, right place. Tell me something cool, unusual that doesn't get planted as much as it should, that when you find the right spot for it and the right client, you can recommend.

Natascha: I'm a big fan of Stewartia. They're not planted a lot around here and I think it's just because people don't know about them. They're a beautiful plant, they offer interest year-round. As long as they're planted properly, they're relatively pest-free. I've seen very few pest issues on them.

Doug: I love Stewartia more than anything. Talk about that, what you say, year-round interest. Give me every season that you like with Stewartia and sell it.

Natasha: My favorite time of year for trees is winter, which is kind of counterintuitive to most people. Stewartia just has a really great exfoliating bark. It's got multiple colors, especially if the sun's hitting it right. It's just a showstopper. It's got creams and bronzes and browns, it's really neat looking, and then it looks good when it's butting out in the spring. Everybody loves to see that beautiful fresh green coming out. Then it blooms late June, around here, early July. I think they look like big strawberry blossoms. I think they're really cool looking blossom. In the fall, the fall colors, it's just like an orangey, reddish. It's just really cool. I love it year-round.

Doug: I have mine sighted that when the sun sets and comes through the trees, it illuminates that exfoliating bark, and you are right.

Natasha: That's got to be amazing.

Doug: It's just something about it. For me, mine's been in the ground, I don't know, three, four seasons now. I'm still too new to it. I guess it's still a surprise for me when I come around the corner and it's blooming. I guess I would say the blooms to me look more like peonies, but that's good explanation; strawberry blossoms. That's a great tree.

Natasha: It really is. It's one of my go-to for recommending something to somebody who wants something unusual.

Doug: Hardy-wise, no problem in Cape Cod?

Natasha: No, none at all. We have a garden museum here called Heritage Museums & Gardens, and they have a section of probably 8 to 10 of them. There's two different kinds and it's a beautiful little spot, they call it the Arbor Bowl, and they're big. They've been there for quite a while.

Doug: Just like anything else, there's different cultivars of Stewartia, is that what you're telling me?

Natasha: Yes, there's two that I primarily think of. There's one that's kind of almost got more of a copper bark.

Doug: That's going to be something I'm going to have to search out, I didn't even know that. Natasha, I'm telling you that went by so quick. I think you and I could talk for another half hour about trees and what you're doing. I just want to thank you for coming on again and I can't wait till we can talk again. That was so much fun. I need to do a deep dive on biochar though one of these days.

Natasha: It's a new one, it's definitely a learning curve.

Doug: Thanks, Natasha.

Natasha: Thank you.

Doug: Tune in every Thursday to the Talking Trees podcast from the Davey Tree Expert Company. I'm your host, Doug Oster. Next week, it's Pruning 101: why late winter is the perfect time to get the job done and information on how to prune the right way. Do me a favor, subscribe to the podcast, you'll never miss one of our fun episodes. We're getting lots of great ideas and feedback through email. Send me a message to, As always, we like to remind you on the Talking Trees Podcast, trees are the answer.

[00:24:17] [END OF AUDIO]