Arborist Answers Your Questions PART 2

We sent in your questions, so in this part two episode, Davey arborist Lou Meyer answers them! To submit a question for a future episode, email us at podcasts@davey.com.

In this episode we cover: 

• Planting trees in wet areas (0:40)
• Replanting where a tree used to be (5:04)
• What is the best treatment for moss in your yard? (9:23)
• Japanese stiltgrass (13:29)
• Why you shouldn't plant a mulberry tree (16:48)

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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

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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 more. Tune in every Thursday to learn more because here at the Talking Trees podcast, we know trees are the answer.

Folks, I'm back with Lou Meyer. He's a regional business developer for the Davey Tree Expert Company in the Atlantic region. Our last episode together, we answered your questions, and that's what we are going to do again today. We're kicking it right off with Cynthia again. This is her third question. This is long and involved, Lou, so hang in there.

Lou Meyer: It is, but it's a really great question, and I'm glad she's asking it because it's something that we get asked a lot. Go ahead, Doug.

Doug: Here's what she says. "I do have an additional question about another tree in the same community, native plant garden, as the redbud. Garden is managed by a team of master gardeners and located about an hour north of Philadelphia, PA." Here's the background. "In a lawn area with thin, weedy turf, the township removed an old locust tree which had grown large and made access to the flagpole difficult. This was in 2022. We planted a sourwood in clay soil, heavily mulched with arborist chips and cardboard to suppress those locust tree sprouts, and used a gator bag for watering.

Sourwood leafed out but quickly declined in 2025. All leaves died, and the tree looked dead, but a scratch on the trunk showed green underneath. The planting bed sank slightly. Maybe from the decaying roots, and was extremely wet from heavy rain we had in June. We regraded the planting bed, popped out the root ball, which was 18 inches wide by 10 inches deep, moved it to the edge of the planting bed, where it's drier and higher. What happened?"

That's a long one, Lou, but what are you thinking when you hear that description?

Lou: I love that she provided so much detail. Cynthia, thank you for that. A lot of times, people just call and say, "My tree died, what happened?" There's a lot that goes into that. Not only did Cynthia provide this, she also sent a few pictures for us to look at, which we can't show you in a podcast. It shows a very full and green sourwood at the beginning of 2025 summer. It shows a yellowing out probably around June or early July. Then, finally, some dead leaves and what looks like just a stick right now.

Like she said, when she scratched the surface of the stem, though, there is showing some greenwood underneath. Yes, a big part of our job as arborists is playing plant detective and figuring out what happened with these situations. Of course, there are always a myriad of possible answers out there, and rarely is it one silver bullet that caused it. Sometimes it is. In the case like this, where we can't really inspect the tree firsthand, we're going to have to go off the pictures and her description. My immediate reaction is likely it is too wet where she planted this.

Sourwoods are a native tree to the United States, mainly in the southeast. Although it can be planted up north, it's certainly hardy enough to do well. I love them. I think they're beautiful trees when you see them. An underused tree in our urban landscapes up here. I wish we saw more of them. They like well-drained acidic soil. First, going back to the removal of the tree. You remove the locust tree, they ground out the stump. She doesn't say that here, but looking at the picture, it looks like there's stump mulch that's been mixed around there. There is some of that stump mulch.

When you do that, you create this impression that's like a bowl, and that you glaze the side when that stump grinder is going really fast. This happens sometimes when you use a tree spade to dig holes too, or a mechanical auger, is you glaze the sides. Most of our soil in the eastern United States is pretty clay-heavy. When you have a machine going really fast, it'll heat up that soil and cause it to harden ever so slightly. It's not like you're turning up this clay soil into a pottery barn. It's enough to harden it a little bit. That will hold water.

When you go a year later and you plant a new tree in this hole, you've got this depression. If it rains hard for a long time, that depression fills up with water. You may not see it on the surface, but your poor little sourwood is floating in a bowl of soup there. They don't like wet feet. That's one thing. Whenever you replant where a tree used to be, I like to wait at least two to three years after grinding out that stump to replant in the same spot. Now, I understand that's not always a possibility. Sometimes you have a small yard, you removed a tree, you want another tree immediately, I get it. If you do that, make sure that the stump grinder knows that they're going to go a little deeper.

Then, when you go to replant, make sure to get all that stump mulch out of there. Where those sides have glazed, where it's just really hard, take your shovel or spade and break up the sides. Scar it up, as we say. Cut lines in it so it's not such a stark difference between the soil that you're putting into the hole and the walls of that wall.

Doug: Now, with a locust tree, when you grind the stump out, are you ever going to get rid of those sprouts that are coming up, or is there a timetable on it where a couple of years later they won't come up? What are you thinking? What have you seen?

Lou: The best way to deal with that is take out the main stem, grind it down, and then you're going to have to be proactive over the next few years. Anytime you see a little stem pop up, cut it off. This root system needs to photosynthesize. It needs to create sugars to live. Now, locusts will hold a lot of carbohydrates or sugars in their root system so that they can resprout for a few years after you cut down that main stem. If you continue to remove those little sprouts before they have the opportunity to leaf out and create more sugars, eventually that root system will die.

Yes, they're a little tougher than your oaks and hickories and other hardwoods that are out there. They're an aggressive tree, but you can do that. I would wait two to three years. As far as your sourwood goes, Cynthia, moving it to the edge where it's drier and higher is a great idea. The number one killer of trees that we see when people plant their trees is that they're planted too deep. People dig a deep hole, and they stick their tree in there. Cynthia, it's okay. You're not alone. It happens to everyone if this is the case. Don't feel bad about it.

I've planted trees too deep plenty of times in my life. I'm a professional. It happens. What you want to do is when planting a tree, where the trunk of the tree meets the roots, it begins to bell out some or flare out. That's called the root flare. You want that flare to be two to three inches above the soil level. You want to see that flare as the tree gets bigger. If you look in the forest or a natural area, all the trees that you see have that bell, wider base. When trees are planted improperly, as they get bigger, they look like utility poles going straight into the ground. That's what you don't want to see.

That's also one of the pitfalls of planting where a tree had recently been removed is that soil has been disturbed. It's going to slowly compress and get deeper and deeper. Planting a tree right on top of there, you may have planted at the right level upon planting, but over the course of a season or two, as rain falls, snow falls because you're north of Philadelphia, it's freezing and falling, all those air pockets break down, and your tree begins to sink into the hole. All of a sudden, your tree that was planted correctly is now at an improper planting depth.

What happens then is the parts of the tree that are supposed to be above ground are now below ground. Rot begins to set in. Then your vascular system, which is the cambium, which is the outer layer of the tree, as that rot sets in, it begins to damage the cambium. The tree can no longer translocate fluids and sugars, and the other things. Then the tree slowly dies out. I'm guessing that's what happened on this one.

Doug: Before we get to our next question, I have one for you. Did you really plant a tree too deep, or are you just trying to be nice for Cynthia's sake?

Lou: No, I've planted trees all sorts of wrong ways. Always with the green side up, though. I learned that one early.

Doug: Let's hit our next question. It's from Richard. He says, "In a recent podcast talking about the soil quality and newer development, someone mentions that it is hard to modify the pH of the soil." I think that was Zane who said that. "Our area is quite wooded, and the neighbor down the hill has been applying lime twice a year since the late 1980s to mitigate the moss in his yard. If it is so hard to change the pH, what is the best treatment for moss?" Here's another aside, though. "I know that trees are the answer, but Davey also does lawn care. I know because my Kent, Ohio lawn is stunning." All right, Rick. Before you answer, Lou, here's my opinion on moss. Love your moss. Moss is an amazing thing, and it's beautiful, and people try really hard to get it to grow in their yard. If you hate it, what are they supposed to do, Lou? Is pH the answer?

Lou: Yes. I'll side with you that I love moss. I think it's beautiful. My kids, I've got a 10-year-old boy and a 6-year-old girl, and we use moss to make fairy houses. We use moss in art displays, and it's great habitat for critters. I totally understand if that's not what you want, especially if it's in the front of your house or where people are looking. I do want to shout out to Rick's lawn care technician. Whoever you are out there in the Davey world, good work keeping Rick's Kent, Ohio lawn stunning. Good work there.

For moss, yes. Changing the pH of the soil is really difficult. I know in our last question and answer podcast, we talked about using pH changes to allow for iron uptake in Cynthia's tree. Yes, pH is hard to change. Liming the soil is something that we've done for years to help manage pH in soil. It does. It just takes years of doing this. It's not something you would change overnight. For you, Rick, to manage the moss in your yard, here's some simple things you can do.

Number one is grasses can out-compete the moss. You want to identify and plant some shade-tolerant grasses. Moss is usually growing on the shadier sides. Usually, on the north side of a house is where you see this. Now, you're in Ohio and Maryland. He says he's got properties in Ohio and Maryland. I live in Maryland. I'm from Ohio. I know both those states really well. Shade-tolerant grasses in our region are going to be annual. This is something you're going to have to do every year is plant shade-tolerant turf seed. As that turf comes in, it's going to out-compete the moss. You're not going to see the moss.

Nitrogen is really important for moss. Usually, when nitrogen is low, that's when moss is growing also. Make sure, again, before you start making major changes to your soil, you're taking a soil test, you'll probably find that the nitrogen is a little low in those areas. A little bit of nitrogen goes a long way, especially if you're planting those shade-tolerant turf seeds. Make sure the nitrogen is correct. That'll help out.

Aerifying your soil. I'm guessing our good buddy, Zane Raudenbush, would agree with me. Aerifying and overseeding your soil is the best thing you can do for the long-term health of it. Soil that is compacted doesn't allow water to percolate down into it. Mosses love that. Make sure to aerify your area that is getting mossy, getting the right nitrogen mix into the soil. Then overseeding with shade-tolerant turf seed will really go a long way to help mitigate the moss that's present in your lawn, Rick, and allow you to have some green grass even in the shady areas during the summer sun.

Doug: Let's continue with Rick. This time, Lou, we were able to get more than two questions. This is pretty amazing because we do like to talk about trees and all these different plants, that's for sure. Rick says that he had been listening to the podcast on invasive species, talking about his property in Western Maryland, and has an infestation of Japanese stiltgrass. He says, "I've been pondering the progression of this infestation and wonder if you have any insights." That's a bad weed, Lou. That is a really bad weed, Japanese stiltgrass. What are your recommendations for dealing with it?

Lou: Japanese stiltgrass is one of a number of these invasive ground cover weeds that are not just unfortunate for us from an aesthetic standpoint, but are really crowding out our native vegetation on forest floors and are an ecological problem. We are being contacted by municipalities throughout the Mid-Atlantic and everywhere that Japanese stiltgrass is, and other areas where other invasive ground covers are found. Yes, it's a tough one to control because it spreads rapidly. Western Maryland, we go out there all the time to hang out in the mountains.

If our listeners don't know, Western Maryland is in the Appalachian Mountains. It's beautiful country. It's a really cool place to visit out there. Cumberland, Maryland, is a terrific city on the foothills of those mountains. We do a lot of work at the Allegheny College of Maryland out there, a lot of their forestry grads. Come work for Davey. I know we've got a lot of Allegheny folk on staff that we love hanging out with. You get out to Garrett County, and Wisp is the mountain that has ski resort. You've got Deep Creek Lake out there.

Western Maryland is a vacationer's paradise. The stiltgrass loves being on forest edges. Sometimes you have it on forest edges. Sometimes you have it in your turf or in your landscape. It is an annual plant. It drops seeds in the fall that comes up in the following spring and last through the year. A two-part approach to it is helpful. In the late summer, early fall, before it goes to seed, cut it down. Cut it down before the seeds pop up and before it starts getting warm. When it's cool enough that it won't reseed. That will help decrease the amount of seed that's hitting the ground for next year.

The second part of that is to use pre-emergent in the spring, and like you would with crabgrass as an annual weed that's in your lawn. If you have the Japanese stiltgrass, a pre-emergent in the spring will keep the new seed from germinating and popping up through the soil. It's that two-part approach that will help control Japanese stiltgrass.

Doug: That is a tough one to deal with. Since it's an annual, though, as long as you don't let those seeds do their thing, I think you should be okay, right?

Lou: Yes. On a large ecological scale, it's going to be a tough one to control. On your property, you should be able to take some steps to put a dent in its population.

Doug: One more from Rick. He says, "Also, a few podcasts ago, you made a comment about never planting a mulberry tree, but did not mention why. Having one in my backyard in Kent, Ohio, I was wondering your reasoning." Let's hear it. Why no mulberries?

Lou: There's two main mulberries that we find here in the United States. One is a native, the red mulberry, and one is an invasive species, the white mulberry. This gives us an opportunity to discuss a little bit of invasive vegetation and foreign tree species. A lot of them were brought here with good intent and for good reason, and then got out of control. White mulberry is one of those. The white mulberry is used in silk production. Silkworms need white mulberry to thrive. If you're a silk farmer, and they tried to bring it here for silk farming, you need the white mulberry. Is native to Asia, does great over there, is fine. Here, it's an exotic invasive that spreads rapidly.

Red mulberry is native to the United States. It also spreads rapidly. That's really the main reason. See, I like mulberries myself. They attract birds. If you're a birder, a mulberry is a great way to go. It also attracts other wildlife.

Doug: The funny thing is, Lou, I love mulberries too, but you don't want them over your driveway or your sidewalk. That's another issue, too.

Lou: That's the main one. Whenever people request tree species, the things we always hear are, I want a tree species. I want it to flower year-round. I don't want there to be any mess. I want it to be easy to grow. That's the unicorn tree right there. The messy part's the tough one, especially with mulberries. They drop their fruit like crazy. If you have one over your driveway, you're going to have fermenting mulberry fruit on your driveway for months during the summer. You're going to have birds eating some of them, but they're not going to be able to out-eat the production of these trees. They're prolific fruiters.

Yes, you'll have fruit dropping onto your car. It'll be staying in your car. It'll be staying in your driveway, your sidewalk, your patio, your pool. You really don't want them over things on your property. Again, because they have so much fruit, they spread quickly. If you have one, it's probably not going to be the only one you have.

Doug: Knowing you, Lou, I have to assume you've got some folksy recipe for mulberries. A pie, a Baltimore something or other?

Lou: Oh, yes. You can make mulberry wine. You can make mulberry beer. You can make mulberry pie. My daughter and I one of our favorite pastimes is going up to the Howard County Conservancy, a nature conservancy around the corner from us, and she will just feast on mulberries when they're in season.

Doug: That's the thing. They're good. They're tasty. Like you said, you're never going to have just one, and you want them in the right spot. As we always say, right place for the right tree.

Lou: You bet you. That's right.

Doug: All right, Lou. That was part two of our questions. We know we have at least a part three, and we're going to be asking listeners to send us more questions, and we're going to continue this. This was a lot of fun. Thanks so much again. Always great to talk to you, buddy.

Lou: This was a blast, and I want to thank the folks who did write in already. These are great questions. Keep them coming.

Doug: As I said, I'll be back with Lou for a part three at some point. If you would like to have your question used on the podcast, there's a couple of different ways you can send them to us. You can email podcasts@davey.com. That's P-O-D-C-A-S-T-S @davey.com. You can also click the link at the end of our show notes to text us a fan mail message. We'd love to get your question. Now, don't forget to tune in every Thursday to your Talking Trees podcast from the Davey Tree Expert Company. I'm your host, Doug Oster. As always, we'd like to remind you on the Talking Trees Podcast, trees are the answer.

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