What's Growing On My Tree? - Black Knot, Galls & Other Growths

Brian Sieber, district manager of Davey's Cincinnati office, talks about different growths that could be harming your trees, such as black knot and galls. 

In this episode we cover: 

• Black knot (1:02)
  • Pruning infected trees (3:08)
  • How to avoid black knot (4:08)
  • Are healthy trees resistant to pathogens and pests? (5:09)
  • Does cutting out black knot save the tree? (5:47)
  • Black knot in the fall (6:39)
  • How has the weather affected Cincinnati's season? (7:09)
• Galls (8:56)
  • How to know of galls are harming your tree (10:26) 
  • Send pictures of your tree to your arborist (11:28)
  • Pay close attention to your tree (12:55)
• Cool native species for forested areas (14:58)
  • Hackberry tree (15:00)
  • Kentucky coffee tree (16:05)
  • Catalpa tree (17:25)
    • Catalpa worms (19:12)

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

To read our blogs to learn about the different kinds of growths that can harm your trees, click here - Tree Care Tips, News & Checklists | Davey Tree Service Blog 

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 Davey 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. I'm joined again this week by Brian Sieber. He's a district manager in the Cincinnati office for the Davey Expert Company. Today, we're talking all about what's growing on my tree. Hi, Brian. How are you?

Brian Sieber: I'm doing good, Doug. How are you doing today?

Doug: I'm not doing bad. We're not getting any rain. I hear you guys are getting rain every day.

Brian: We are getting a nice, short, very burst of thunderstorms at the end of almost every day this week after a brutal 80, 90-degree day. It's lovely. Lovely in Cincinnati this time of year.

Doug: And humidity.

Brian: Oh, we can't forget about the humidity. That's a joy for everybody, I think.

Doug: Let's start with black knot because I know that can be a bad one. Explain first what it looks like on a tree.

Brian: Black knot is super noticeable on a tree. It's something that every homeowner, if you have a tree that's susceptible, let's say a Canadian cherry tree or pretty much anything in the cherry family, it's a giant black growth that is along the branch stem. It almost looks like somebody molded a big piece of clay around the branch itself. It's super noticeable, and it brings a lot of concern to people.

Doug: Is it only cherries or are there other trees too that you see it on?

Brian: I only see it locally on cherry trees.

Doug: Is it a death null for the tree or can it be treated? What do you do?

Brian: There's a couple of things that you can implement to lessen the progression of the plant and the detriment that something like black knot might cause. Black knot is a fungal disease that gets on cherry trees through the lenisol pockets that are on there. It propagates in the springtime, and the growth constricts the flow of nutrients out to the branch tips.

What ends up happening with a lot of the Canadian cherries we see around here is they survive a good number of years with black knot on there. Then, consequently, the branch ends start to die at some point in time when the constriction gets too great around the branch. There's a number of methods that people employ, but the one that I've seen most common that works is usually when you get into the fall season, you can go through and prune out those sections that have those branch growths on it.

It will create an abnormally shaped tree originally, but a lot of the trees that we use this method on, they have a root system that's very healthy, viable, and they can recuperate those branches, especially as they promote their new growth in the springtime after the fall pruning.

Doug: I know when I've talked about pruning before, arborists have discussed disinfecting the blade between cuts. If the tree already has fire blight, do you have to do that between cuts or you just can cut the stuff off?

Brian: No, if you're dealing with anything that's viral or bacterial or fungal in a tree, you always want to try to disinfect your instrument tools in between the cutting sections. That's so you don't inadvertently take any sort of pathogen from one part of the plant and transfer it to another one. That's always good practice.

Doug: That makes sense. Any other types of treatments for something like black knot, or the best thing to do is just cut it out?

Brian: We've worked in the past about applying various products that might have some effect on the pathogen, but no, for the most part, we've found that eradication of it, or at least cutting it out on a repetitive basis, seems to promote the most longevity in that plant in the landscape.

Doug: Is there any way to avoid it?

Brian: Yes. You try to be aware of what your neighbors have as far as plants that they have in their landscape is a really good one. On my own property, on my own house, I tend to go through and look-- before I plant anything new on the property, I look at what the neighbors have and try to create some plant diversity. A lot of things that we find that cause plant healthcare issues need viable hosts of the same species.

A lot of the times, you might have problems with boxwoods on the neighbor's property, and so you wouldn't want to plant a bunch of boxwoods on your property if the neighbor's having issues with them. If you have your tree that has a bunch of black knot, or the neighbor's tree has a bunch of black knot in their tree, you might not want to plant another tree that's very susceptible to that specific problem. Consulting your local arborist, maybe getting a second opinion on what's in the area is always a good idea.

Doug: Does the health of the tree help fight off a disease like that, or because it's fungal, that doesn't come into the equation?

Brian: All trees have a natural resistance, just like us people have a natural resistance to all sorts of pathogens or insects, or anything else that might be coming after us. A healthy tree is always going to be more resilient and resistant to those pathogens or those insects or whatever it might be that's trying to get into the tree. The healthier it is, the better off it's going to be, and the more it'll resist it.

Doug: Have you seen trees that if you cut it out, they've been fine, or does it eventually take its toll?

Brian: The problem that we have in our area is we serve a nice big residential community, and they're under constant exposure from a lot of the same pathogens most of the time. We have trees that we maintain on a relatively consistent basis. Like for black knot, for example, we might go through and cut out the trees and limbs that are affected once every two to three years and do that for a 10 or 15-year span.

Sometimes that can go for a very long time, and you can really maintain it in the landscape. It's up to us as stewards of the environment to really go through and take that part seriously and make sure it's a prerogative for us if we want that gorgeous-looking tree to stay in our landscape.

Doug: I'll tell you one thing for sure, when you see black knot on one of your trees, it's pretty scary.

Brian: In the fall time, it sticks out horribly. The growths originally come in about the same color as the bark, but they darken out and they get really almost coal black as the year progresses. When the leaves fall off the plants in the fall time, they really stand out against the environment and the trees.

Doug: This summer, since we talked a little bit about what's happening in your environment, how has the weather affected your season? Has it been a good season, a tough season? How would you categorize it?

Brian: Doug, that's the part I love about this industry is that every year it's a little bit different. Right when you think everything's going great, Mother Nature throws you a bunch of curveballs that you weren't planning on, and then you go, "Ugh." June in Cincinnati, we had an excessive amount of rainfall. We were getting good amounts of rain every week. That's great. Plants love it. Then I'm an avid tomato grower, and I don't always like it when I get too much rain over here because they don't really grow as much as what you want them to.

Always some challenges involved. Here, the regular rainfall has promoted a lot of good growth in trees. It's created an excessive amount of fruit production on some trees, which is really nice. Moving into July and August, when we move into a droughtier part of the year, that excessive growth that we might have had in the spring has some consequences that we have in the latter part of the summer.

Doug: I had to put my tomatoes in early because I was traveling, and they have not recovered. It was a very cool, wet spring, and they just never really-- we're going to get tomatoes, but it's not going to be like one of those like last year where even though we had a drought, that was a better situation for us than a cool rainy spring. Like you said, that's the fun of working with plants, is that every year is a little bit different.

Brian: It's a challenge. It is. That's the joy of it. That's why we love it.

Doug: Let's go to some other things that are growing on trees. Tell me what a gall is because I don't know what a gall is.

Brian: The easiest way to describe a gall is it's an abnormal growth on a part of a tree. Most often, we can find galls on leaves. It's the easiest way to see galls. They can occur on branch stems, but it's an abnormal growth on it. It's caused usually by an insect or a mite or sometimes a fungus or a bacteria can create a gall.

The tree reacts to that infestation by creating a barrier around it. Sometimes it's a protective barrier created by the infester, not particularly the tree. We can find that in a whole host of trees that are out there. Some are detrimental and can cause some long-term damage and some are not.

Doug: So sometimes it could be something as simple as just some bumps on a leaf, right?

Brian: Absolutely. I have a gorgeous hackberry tree in my backyard. It provides me great shade. Every year, I get these little bumps that are, I don't know, I want to say about the size of a pencil eraser, all over the leaflet. They look horrible, but they don't cause any long-term damage to that tree. The tree still has plenty of leaf foliage. The leaves grow normal without too much of a problem other than the odd appearance on them. The tree survives perfectly with them on there.

Doug: In general, unless it's a certain specific type of gall, is it usually okay for the tree, or how do we determine if it's one of the bad ones?

Brian: The easiest thing I would say to do is always first consult your local arborist and have them out there and identify it because galls can be caused by insects, they can be caused by mites, they can be caused by fungus, they can be caused by bacterias, stuff like that. You want to have a better understanding of what the gall is, what the cause of it is.

Most galls, I would say, are pretty inconsequential to trees. They're just ugly-looking. Some galls, like, for example, horned oak gall, can be really detrimental to an oak tree if in the tree for a long period of time. Your arborist professionals are out there. They're out there to help you, and they're out there to make sure your landscape is something that both you and I can enjoy. Use them. They're there for it.

Doug: With the arborist from Davey that I work with, he always comes out, but I was just thinking, does anybody ever send you pictures? Does that help, or you've got to be on site?

Brian: No. For me and a lot of the clients that I deal with and the people in the community, I make my contact information readily available. I'll get phone calls, text messages, emails, where plenty of people just text me a picture or send me a picture of the tree and say, "Hey, Brian, I've got this weird thing growing on my tree. Can you tell me what it is?"

That's the initial start point of the conversation. It's, "This is what I think it is. Let's get together and take a look at it." Absolutely, pictures can be really good at determining what type of gall is there because each gall is pretty distinctive in what they have going on, and knowing the species of the tree can be really helpful when identifying what the infestation is as well.

Doug: Certainly, I have to imagine in your job that it's so seasonal that when you start to hear a lot about one thing, you see it in a lot of different properties.

Brian: Oh, absolutely. Then homeowners notice it too. When you educate a homeowner or anybody in the community about some of the things that are going on there, they start to pick up on it too. Then they see it pretty much in a lot of places where they go, which is nice.

Doug: What else can you think about when we're thinking about trees that if I go out there and take a look and I see something growing on there, what would be something you could think about that I would notice and say, uh-oh?

Brian: We get so accustomed that it's really a knack. It's a trick to be able to walk around your community and actually look up at the trees and plants. For me, that's the first thing. I have so many people that I meet in the community that we talk about trees all the time, and it's often that just working on observational skills of just, "Hey, this is what this tree looked like for years and years and years, and something's a little off this year, and I'm not sure what it is."

That might be a discoloration in the leaf, that might be a section of little dead branches, or that might be, in this case, an abnormal growth that's going on there. Big growth on a branch that looks a little weird. Round cylindrical branch contusions aren't normal on any tree, so seeing stuff like that is something that you might look at and say, hey, that might be something I want to send my arborist and see what's going on there.

Doug: Brian, you're so right because even though I host the Talking Trees podcast, I don't spend the time I should looking at my trees. It just seems that all of a sudden, I'm looking at one, and then I'm looking through the woods, and I'm like, "Oh, no." Then I make my call every six months.

Brian: Every six months.

Doug: Vince, from Davey Tree, is over, telling me what he's going to have to cut down. I probably talk about it way too much on the podcast, but I have oak wilt going through my property. It's sad. Every time that I am losing an oak, I'm replacing it with something else. Again, I want, like you said, diversity in my forest. I'm always looking at a native tree for a replacement.

I'm going to put you on the spot because I know it's right tree, right place, but in a forested area, give me some ideas for some cool natives. Before we even start there, I got to ask you about hackberry. Every once in a while, it comes up on the podcast, but I really don't know much about it. Since you're in Cincinnati and I'm in Pittsburgh, I'm assuming it would work here.

Brian: It'll work great over there. I have a hackberry tree in my backyard. I absolutely love it. They're tall-growing, deciduous trees. They thrive in a forested environment. They provide great shade. They're called hackberry because they have a little berry about the size of a sweet pea on it. That's the fruit of the hackberry tree. Great shade tree, a rough, coarse bark, but it really can thrive in both an urban and a residential or suburban and a forested environment without too much of a problem. I like them.

Doug: All right. What else would be on your list?

Brian: If you're replanting in a forested-type environment, so you've lost a couple of oak trees and you're looking to put something else in those spots, down here in Cincinnati, I've really become a fan of the Kentucky coffee tree. It's a lot more prominent to our Kentucky neighbor than it is in Cincinnati, but the foliage is really nice. The bark structure is really pretty. It grows tall, provides good filtered sunlight in the shade. I really like the Kentucky coffee tree because of that reason. Not popular either, so not a lot of people have them.

Doug: It's very underused in the landscape. There's actually a place that I go, a nursery that I speak at, and they've got them growing out on the edge of the lake. They're really cool trees. The first time I saw it, I was just like, "What is that? That is really a cool tree."

Brian: If you plant one and you know they're not very popular and not a bunch of neighbors have them. Not only that, but it's a great conversation starter and to build passion and enthusiasm within your community about trees and plants. When you have something like a Kentucky coffee tree or some of the lesser-known plants that are more diverse out there, you can educate your community about it as well and really brag on the fact that you've got some neat stuff going.

Doug: Do people still plant catalpa?

Brian: Not as much as what I wish. We get an insect called the catalpa worm over here, and they chew up the catalpa leaves pretty much.

Doug: Is it every year that that worm does that? I've read about it.

Brian: The catalpa worm is pretty frequent. We see them growing in groves a lot of the time, and so there'll be a multitude of catalpa trees. I love catalpa trees. The leaves are just gigantic, and they have these gorgeous-looking, long, angelic-like bean pods that come down from them, almost in a long cigar shape. They're gorgeous trees. Branch structure is amazing on them. The bark is wonderful.

Doug: I grew up with one. That's why I love it. Every once in a while, I'll see one out there. Is it something you could get in a nursery nowadays?

Brian: Oh, absolutely. You might have to shop a couple of different nurseries. In Cincinnati, we have a couple of relatively large ones, so they have a really good, diverse run of plants that they have access to. You would have to consult maybe your local two or three nurseries, and maybe do a little digging for it, but sure, absolutely. They're gorgeous.

Doug: In Pittsburgh, we have a couple of specific tree nurseries. I bet you they would have it. Just in our conversation, that popped up in my mind, that catalpa. That might be another one I might throw in there and see if I like it.

Brian: They're such a fun tree. The bark on those is nice. It's relatively smooth. The leaves are just-- when I say big, the leaves are the size of your head big. They're gigantic. They're gorgeous and heart-shaped, just pretty as can be.

Doug: I'm Irish. I have a giant head, so that's saying something. [laughter] One side note on the catalpa worm, it is a prized bait for fishermen.

Brian: I know it. The catalpa worms are big. They're about the size of your thumb and about as long as your index finger. Fishermen, they have to catch catfish with those. They're gigantic. Have to.

Doug: Well, we've covered things that are growing on trees. We've covered tomato growing. We've covered fishing. I think we've done it all, Brian. [laughs]

[music]

Brian: I think we have, too, Doug. I think we have, too.

Doug: Well, it was great talking to you again. Appreciate all the information, and we'll talk to you next time.

Brian: Absolutely, Doug. Absolutely. Can't wait.

Doug: Tune in every Thursday to the Talking Trees podcast from the Davey Tree Expert Company. I'm your host, Doug Oster. As always, I need you to do me a favor. Subscribe to the podcast so you'll never miss a show. What would you like to hear on the podcast? Let us know.

There's two ways to reach us. Send us an email to podcasts@davey.com. That's P-O-D-C-A-S-T-S@D-A-V-E-Y.com. You can also click the link at the end of our show notes to text us a fan mail message, and your ideas could be on a future podcast. Love to hear from you. As always, we'd like to remind you on the Talking Trees podcast, trees are the answer.

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