Ep. 249 Common Tree Diseases and Insect Pests in Illinois and What to Do About Them | #GoodGrowing
Welcome to the Good Growing podcast. I am Chris Enroth, horticulture educator with the University of Illinois Extension coming at you from Macomb, Illinois, and we have got a great show for you today. We're gonna be talking about the creepy crawlies, the infectious pathogens that spread about our landscape infecting our trees. Because it's tree month, and we wanna talk about these things because we like trees. But you know I'm not doing this by myself.
Chris:I'm joined as always every single week by horticulture educator Ken Johnson in Jacksonville. Hey, Ken.
Ken:Hello, Chris.
Emily:Oh. Oh my gosh.
Chris:You got me. Oh, hi, Ken.
Ken:Hopefully, I'm on for for a while here. We'll see.
Chris:Mhmm. Yep. We'll see how this gets cut together. But if it's all in there, folks, we're we're having Internet woes today. So we'll we'll see how long everything lasts here.
Chris:This may never see the light of day. Ken, we have to bring on, of course, our tree companion, compatriot advocate, Emily Swihart, horticulture educator in Milan, Illinois. Emily, welcome back.
Emily:Hi, guys. Thanks for having me, and, yeah, let's try to get through this. Poor Ken. I know you this is the podcast for you. Like, we're talking about things for you.
Emily:You've suffered through or tolerated the last couple of podcasts about trees. We thought we'd maybe bring in some of your creepy crawlies. And Yeah. It's gonna it'll be fun.
Ken:Trees are fighting back there, disrupting our Internet. They are. Yes. Yeah.
Chris:So we we will we'll we will push back with knowledge. So today, we are chatting about infectious things. We call this biotic stuff, the the the biotics bioticism. That's not a word. Ken, as the captain, the leader, the the professor of integrated pest management, IPM, doctor, could you define what we mean when we talk about, like, biotic things?
Ken:Yeah. So a lot times when we talk about disease, we talk about abiotic or biotic diseases. So abiotic are those nonliving problems. So that'd be drought, freeze, flooding, things like that. These kind of more or less one off events, whereas our biotic are our living organisms.
Ken:When we talk about diseases, fungus, which is majority of what our diseases are gonna be are fungus, bacteria, viruses, phytoplasmas, all those fun things fun things are living. They can replicate, reproduce, and spread to the environment. So usually, when I we're talking about these diseases, we kinda have that continuum. We have our healthy tissue. We've got symptomatic disease tissue, and then potentially have dead tissues and stuff.
Ken:So you kinda have a continuum, whereas our abiotic is kind of a a one off. It affects not necessarily everything but, you know, a large chunk of the of the environment or the landscape. Whereas a lot of times, biotic are a little more specific to what they're attacking when we're talking about diseases.
Emily:And you should mentioned, you know, that there's abiotic and biotic, and they're not always separate from one another. I think we need to kinda touch base on that. Right? Like, so an environmental stress can make a tree more susceptible to some of these biotic diseases. And so, know, trees are living, complex organisms.
Emily:You know, our environment is complex. And so as we go through some of these, I think it's important to keep in mind that if you have a biotic challenge with your tree, it might not be the first thing that occurred with that tree. You know, because we're caring for trees as we're managing them, potentially management practices, you know, environmental stressors can make a tree more susceptible to some of these pests and diseases. And so there's what's called, like, the decline spiral. I think it's been talked about many times before on the show, but, basically, this means it's a theory that you know, a a tree can start to fail with one thing.
Emily:It kinda compile you know, issues can pile up on each other and and lead to the decline of a tree over time. And so biotics are often blamed for tree decline, but you know, and and tree failure, but it's not always well placed blame.
Chris:Mhmm.
Emily:Sometimes it is. We'll talk about some where it's absolutely well placed blame, but sometimes it's not.
Ken:Yeah. A lot of times they're many times, they're they're kind of finishing the tree off. They're not necessarily the the initial cause, but they they finish the job. Yeah.
Emily:Yeah. Yeah. I think it's also important to note that it they don't always it's not always one, you know, biotic issue or one you know, like so sometimes people will come in and be like, what's wrong with my tree? And it's there's multiple biotic things going on. Some of them are harmful.
Emily:Some of them are are not. Just they're, you know, like bores, for example. Some bores are really can be challenging for trees. Others are just part of the natural ecosystem, and this is you know, it's not a problem. But they don't always they're not as easily separated out in the landscape or, you know, it's not just one diagnosis.
Emily:And so I guess I just before we get into this, you know, we'll talk about individual kind of issues, but sometimes it's multiples on a tree. So keep that in mind, folks.
Ken:And just because you have a disease or a pest doesn't mean it's a a death sentence for your tree either.
Emily:Correct. Yeah. Yep. And sometimes it doesn't mean you even need you need to do take any action at all. So yep.
Emily:Good point, Ken. So the way we set this up is we there's a lot of biotic, you know, pests and diseases that we could have talked about with trees. Perhaps we'll do more episodes in the future. But we just for today, we each chose two, kind of to highlight and bring bring to our attention. How did you guys choose yours?
Emily:I'm curious because I had certain criteria. How did you how did you choose your issues?
Chris:Last night, what do I have information about real quick? Yeah. Some things that I'm familiar with and and also items that might be something folks in our Illinois will be maybe encountering.
Ken:I did things that are kinda relevant now or the two I picked are relevant now. Yeah.
Emily:I did similar. I did one that is is relevant now, one that's always relevant. But I also chose them because and you'll I'll I'll get into it. We're not, like, we're burying the lead. We haven't said what we're we're gonna talk about, but one of mine is just really fun to look at.
Emily:So I've just always enjoyed seeing it, even though I know that it's not the most healthy thing for trees in our environment. It's got some ornamental value, and and we'll we we will see it. It's it's in Illinois too. So shall we dive into it, since we haven't said what we're talking about? I'm gonna go ahead and let Ken since you've been you've been fighting to be here today
Chris:All day.
Emily:All day, I'm gonna go ahead and give you the honor of going first with one of yours.
Ken:This is what? Take five or six right now?
Emily:Yeah.
Chris:Yep.
Ken:Alright. So the first one I picked is eastern tent caterpillar. So I was actually driving over to to Pittsfield for a track meet earlier this week and noticed along the the interstate, a lot of the trees are getting that webbing in the notches of the trees, which is eastern tent caterpillar. So this is one of our our native caterpillar species. It is it's typically their eggs are hatching when leaves are starting to swell and and emerge from trees.
Ken:So they are feeding typically on trees and like the rose family, something like cherry, crab apple, apple, things like that. Not that they can't feed on other things, but those are tend to be their preferred hosts. So they'll start feeding. They're building their webs in the notches of trees or those those crotch angles. Unlike our our our fall webworm, which is more at the tips of the branches, and that's in the fall, our our eastern tent caterpillars in the spring and in those notches.
Ken:And so they'll build those. They'll leave that webbing to go feed. The caterpillars, I think, are are kinda pretty, and that's, I think, one of the earliest memories I have is as a kid, you know, we had a bunch of mature trees in our our yard, and we just go around and collect these, like, by the bucketful because as they start to to mature, they'll start to wander before they will pupate. So we just collect buckets and buckets of them. So I don't I don't know what that says about me, but we do that as as kids.
Ken:So the the caterpillars, they're kind of dark body. They've got kinda yellowish orangish stripes on them with some spots and then on the top and then blue black spots and and lines on the sides. I think they're they're pretty caterpillars. And they've got some some longer, little more sparse, long orangish hairs on the sides of them, and they're using these as kind of defense, make it easier or more difficult to to kinda get to the body of the insect. And like I said, they will feed.
Ken:Since they're coming out early in the year, you know, they can do some decent damage because leaves haven't fully expanded. They can defoliate trees and stuff. Fortunately, though, if it's a healthy, well established tree, this probably isn't gonna do any significant damage to them. The trees will be able to recover. If it's a newly planted tree or if it's on, like, tree fruit or something like that where you actually wanna harvest something, probably maybe a little more considered, you may want to look at possibly managing it.
Ken:But on a, you know, a full grown metrosurgery, they've probably been attacking them for a while and those trees will be just fine. They will they will eventually pupate. So there's one generation a year. They'll feed, they'll pupate. They also come out and they'll lay their eggs, kind of these like black clusters of eggs around the the branches of trees.
Ken:So you can potentially go out and find those, scrape those off if you really want to, and they'll overwinter as those eggs. And the egg masses look kinda similar to black knot, which you can find on cherry trees, black cherry trees sometimes. So it you know, if you see that that black mass on there, you may wanna look a little closely to make sure what you're looking at. Like I mentioned, management really isn't all that necessary. If you wanted to manage, you can go in and and kinda destroy those those nests, that webbing.
Ken:Just take a stick, twirl it up. If you do it when it's kinda cooler or cloudy, caterpillar will probably be in there. You can get rid of a lot of them that way. If it's warmer and they're all out feeding, you can just destroy that nest, and then all the predators and parasitoids will come out and find them. That webbing is protecting them.
Ken:When they don't have that, they're gonna get consumed probably pretty quickly by birds and things like that. If you wanted to go the the the pesticide route, you do something like a a BTK, the bacillus thuringiensis kurstakii. That is a a bacterial insecticide. It's only affects caterpillars, so you're not gonna have to worry about other types of insects, bees, beetles, flies, what have you being affected by that. So that's a that would be the one to use.
Ken:And since these leave the nest, leave that webbing, can just spray the foliage. They'll consume it. Whereas, like, when we talk about our our fall webworm, they feed with inside that webbing, so they're much more difficult to control. But these are relatively easy to manage.
Emily:Well, I'm glad you said well, first of all, you collecting them as a kid is totally on brand, so I appreciate you sharing that story. That's like an origin story. I love it. But I'm glad you said about the black knot because it it really does. Like, I thought I've thought that for a a bit too.
Emily:And and so black knot is a fungal disease of of mostly fruit trees, but it the it kind of encases the twig in a more, like like, knotty kind of way. Like, to me, it looks like these eastern tent caterpillar nests are, like, more smooth, and so you can kind of distinguish. Maybe I correct me if I'm wrong, Ken, but that that's how I, like, kind of tell it. Yeah.
Ken:A lot the pictures I've seen of, like, the the tent caterpillars, they look it's almost like scales, like, a snake skin
Emily:Yeah.
Ken:Or something like that, whereas, yeah, the black knot's a little more knobby Mhmm. Warty appearance.
Emily:Yeah. Yep. And black knot's problematic. That needs to be managed. So it's important to identify what you have.
Ken:And then I think the egg mass is kinda shiny as well, which Oh. Black knot isn't going to be.
Emily:And they have one you said this earlier, but, like, so pests, some have multiple cycles in the year. Eastern caterpillar is one. And so if you are seeing them later, that's kinda how you can narrow it down to either whether it is eastern tent caterpillar if it's in the spring versus later in the season. So
Ken:Yeah. Yeah. They're they're one and done if it's yeah. Something in the, you know, late summer, fall, that's gonna be our our fall webworm doing that. And then they're building their nests on the ends, and they'll stay inside of that.
Ken:So and again and then they're really, they're not a big too big of a concern either because they're coming out later in the year where trees have done a lot of their photosynthesizing already. And and for for both of these, regardless if it's eastern tent caterpillar or fall wet one, don't kill them with fire. You're gonna do more damage to your tree than the caterpillar as well.
Chris:Trees are also susceptible to fire treatments.
Emily:Fire. So you can you can
Ken:go on the Internet and find pic videos of people with, you know, homemade flamethrowers and and whatnot. Oh. These are wasp nests, bald faced hornet nests. Yeah. Torching their trees, trying to get rid of it.
Chris:I'm trying to save it though, Ken. I wanna save my tree by burning it.
Emily:I mean, fire is fun, but don't do it. Do it
Ken:like In in the
Emily:right place. Have a have a, you know, in the campfire with some s'mores instead of lighting your eastern tent caterpillars on fire.
Ken:Yeah. Or if you do get a wind them up on a stick and then light it, you use it as a torch or something like that. Sweet.
Emily:Yeah. I still don't love that. But the moths are really pretty, though, too. Like, you know, you said about the caterpillars being kind of interesting. The the moths are I think
Ken:they're pretty. A, yeah, tan brown with some stripes on the wings.
Emily:Yeah. Do what do they feed on?
Ken:I'm not sure if they do a lot of feed. They'd be I mean, they'd be
Emily:Okay.
Ken:Nectar. If they feed a lot of species, though, I don't know about these specifically, the adults don't really feed much if at all. Okay. Basically, they reproduce, and that's the end of the life. But you're thinking think about, like, the the larger large silk moths, like luna moth, polyphemous moths, things like that.
Ken:They don't feed as adults. Some of them don't even have functional mouthparts.
Emily:Can the insect world is super cool. I don't know enough about it, but it's super cool. Whenever you're like, they don't even have mouthparts. Like, that's wild. This is wild.
Emily:Nature's wild.
Chris:They can't even speak poor things.
Emily:No. Or sing. Mhmm. Anyways. Okay.
Emily:Alright, Ken. That was an excellent start. Chris, what do you have for us?
Chris:Well, let's let's keep on this insect train here. So I wanted to talk just generally about, like, wood boring insects. And and, Emily, you had already mentioned this a little bit earlier. We have maybe a little bit of misunderstandings of are these good, bad? Are they supposed to be doing this?
Chris:And I'd say most of the wood boring insects, so these are beetles that females gonna layer eggs on a on a tree, that larva is gonna bore into the tree, feed on the tissue of that tree, and then pupate back into the adult and that's the life cycle. A lot of these that you're going to maybe encounter are supposed to be here in The United in in the Midwest here. They're they have a specific role to fulfill in the ecosystem, and that is a sort of breakdown trees that are already dead or dying that that have undergoing significant stress and return those useful nutrients back into the ecosystem, back to the soil, and and to make room for more plants. So a lot of them are supposed to be here. And I think a lot of people when they think of like a wood boring insect, they think of emerald ash borer.
Chris:At least that's kind of the most recent one that swept through Illinois. And but we have a lot of native ash boring beetles also. So we have the banded ash borer, we have the ash lilac borer, we have the red headed ash borer. These are all from Illinois, and their primary role is to basically begin that decomposition process of that tree and to recycle those nutrients back into the system. So I think before EAB was really confirmed in my neck of the woods, I'd get a lot of phone calls.
Chris:People would say, I have holes in my ash tree. And, you know, it it was either like yellow bellied sapsucker, which is a woodpecker, or it was one of these native trees because before EAB showed up, at least in my neck of the woods, we also had the drought of 2012, which was a significant stress to all plants. And a lot of our ash trees then got attacked by these native bores. And so that was what I encountered most of the time until was it 2014, 2015? Maybe it was 2016 when the EAB sort of started up in Galesburg, which is the county I serve, and then finally wound up here in Macomb where I'm at right now.
Chris:And so it it it spread through. And so now what we see a lot of is a non native insect borer, emerald ash borer. But but but anyway, we have a lot of corresponding native ones. And so ash is not alone in this. So we have, like, the painted hickory borer that's supposed that goes after hickory trees.
Chris:We have a sugar maple borer, a bronze birch borer, the white oak borer, and, you know, just add the tree name and borer at the end of it. More than likely, you'll hit something here in this whack a mole game of of wood boring beetles. But so the ones that we really are concerned with are these a non native species that are coming in. Emerald ash borer, of course, on everybody's mind. And because it's non native, that means it didn't co evolve with our ash trees.
Chris:So in its natural habitat on the other side of the planet, emerald ash borer, it it fulfills that same role that our native ash borers do here. And trees have natural chemical defenses that if they do get attacked by a bore and they are healthy, they can resist, you know, feeding from that particular insect. And because our ash trees in North America did not evolve with emerald ash borer, they don't have the chemical defenses to ward off any attack. And so emerald ash borer attacks healthy trees, trees that are not under stress, trees that are perfectly fine and that are just just doing their best here in our landscapes. There's a couple other non native wood boring insects.
Chris:I think Asian longhorn borer is another one of those. It goes after a variety of species. It's a really I think it's a pretty beautiful insect. It's like kinda large, very long antennae, which is the longhorn part. It's black with white spots on it.
Chris:I think the big big one they're worried about is maple trees. Is that right, Ken, with Asian longhorn borer?
Emily:Yeah.
Chris:But then there's another one, the citrus longhorned beetle. So it goes after trees and that that bear fruits that are like poems, so like apples. So that would be a very big deal if the citrus longhorned beetle got here. And it was identified in Washington state, and they declared it eradicated. But it's been encountered multiple times in different ports around North America, mostly on the landscape, nursery stock coming in to the country.
Chris:Been several bonsai trees that have had citrus longhorn borer in it as well. So that would be really bad news for all of our apple growers if that particular one would show up. But it also feeds on sort of a whole slew of other species of trees including like pecans or pecans, however you like to say it. And sycamore, I think they go after sycamore. So Asian longhorned bore, citrus longhorned bore, EAB, you know, we EAB is established.
Chris:Those other two, though, they're not established, but they have been spotted in The US. So that we keep eradicated when they pop up here and there, thanks to our, you know, is it APHIS? Are they the ones that do the port scouting? Yeah. APHIS.
Chris:I don't know what that stands for,
Ken:but No. Animal plant health inspection service.
Chris:Yeah. Mhmm. So shout out to all the APHIS and workers out there who are checking stuff. I think probably the big thing people wanna know when it comes to these is how do we control them. So first one, don't plant susceptible hosts, which when you're dealing with trees, a lot of times it's too late.
Chris:By the time they show up, they're in the ground for decades already. So and just take care of your trees. I think as we've established, if you have a good healthy tree, they can resist some of this feeding damage. There's some interesting trapping that goes on that really only works for, like, monitoring or kinda, like, keeping track of population numbers. But there is a strategy that they're looking at for some of these wood boring insects where they're going to infect the trap with a fungus.
Chris:So the insect comes in, they're attracted to that trap, they get this fungus on their exoskeleton, their outer skeleton, they fly away and but they're infected and and it kills them. So I don't know if they're employing those yet, but I've heard it as a strategy. The other strategy is just calling trees. So you've figured out where they're established and you go about a half mile mile radius around there and you call out all of their host plants, which they had to do with when the Asian longhorn beetle was discovered in Chicago. They cut down tens of thousands of trees in Chicago.
Chris:They've been found in New York. There's another port of entry where they were discovered. Again, they they just just clear cut several trees to just remove that possibility of spread, which we don't wanna have to do. That's a huge loss for urban canopy. Then the kind of that last option though is gonna be our chemicals.
Chris:So usually these are gonna be systemic that we would inject into trees or use as a soil drench to get into the tissue of the tree. It makes essentially the entire plant toxic to anything that feeds on it. For our for that, a lot of our applicators are turning to imidacloprid. This can be either a soil drench or an injection. The soil drench can be done by the homeowner.
Chris:The injection should be done by a licensed applicator. Timing of this, probably one to two times a year. Late April to May is a good time right before it rains so the tree moves that chemical into the tissue. A lot of times people will call my office and say, I forgot to do it in the in April or in the spring. When when can I can I do this in the fall?
Chris:Well, there is some research that suggests that you can do it in mid fall before the ground freezes. You're not gonna get as effective uptake as if you were doing it in the spring, but it can be done. A few other active ingredients though. So imidacloprid has to be done pretty much every year. There's another one though, emamectin benzoate that can be done every two.
Chris:And if you have a healthy tree with a low pressure of EAB or other wood boring insects, that can be done every three years. Again, this is gonna be injected and it's a restricted use pesticide so it's gonna be done only by a professional so you have to hire someone to do this. You're gonna wanna do it in the spring. There's another one Dinotefrin. It's a soil drench or you could spray it on the bark.
Chris:Soil drench can be done by the homeowner, bark spray, professionals only. You do it once a year in the spring. There's a new interesting one, so a lot of people are trying to turn to organic ones and so azadirachtin is another one that has been employed and is showing mostly successful application. Azadirachtin is actually distilled from neem oil from the neem tree, but it is also an injection, which means we're hiring someone to apply this. And so Faso Direct, and that's one you do every year for heavy pressure, but you could maybe do it every two years for a low pressure kind of population level.
Chris:So that's wood boring insects in a nutshell.
Emily:Very well done, Chris. Yeah. I wanna just so one of the questions I get you probably get this too. We had mentioned emerald ash borer. I get the question of, like, do we ever get to stop being concerned about it?
Emily:You know, I've been treating my ash trees for a while. Like, do I ever get to stop doing that? What is your answer?
Chris:I just answered that question last week. Someone was like, I normally do my soil drench this time of year. Can I stop, please? And I said, nope. As far as we can see in our crystal ball, we are going to be implying these indefinitely.
Chris:Now that might change. There might be some new technology, maybe some biological that gets developed where we stop treating. But far as far as we're concerned, if you have an ash tree, you're treating this thing indefinitely. Yeah. Or if you have an ash tree that you've never treated and is still alive and healthy, we'd love to know about that.
Emily:Call us.
Chris:Yeah. Call
Emily:us. Get you connected to people.
Chris:Yeah. Morton Arboretum. They're trying to track out some of these trees that are resistant. Now it's not gonna be most of our landscape trees because those are all clones, but it's probably gonna be a wild tree out in the forest.
Emily:Yeah. Yeah. There is there are some programs, some breeding programs going on, some monitoring programs of those wild spaces in in woodlands, trying to identify trees that do show some level of resistance to or tolerance of emerald ash borer. And I know that there are breeding programs that are happening just like with, like, Dutch elm disease, like, that came, you know, through and was devastating to the American elm, wiped out, you know, all of essentially, of the I'll take that back. Not all of, but most of our American elm that were close by, there are some still that survived some really large specimen that were isolated.
Emily:That's why I say most of the American elm. But through breeding programs, we were able to insert some of those resistance genetics, and now we have elms that we can plant again. Similar things are happening with emerald ash borer. So I remain optimistic that in our lifetime, we'll be planting ash trees again because their their native trees are beneficial for ecosystems. They're lovely, you know, in in our communities.
Emily:But currently, yeah, we're still treating them if you wanna save them. Another comment, so you mentioned injectables. As folks are considering that or or continue to do that, I've seen some research emerge where that that these are wounds, and we're creating a a number of wounds, like repeated wounding. Typically, kind of in the same area of the tree, like, at the base of a tree is where you're gonna be injecting some of those chemicals. And so that can cause like, over time, can cause adverse health effects for Mhmm.
Emily:Ash trees. And so something to monitor, working with an arborist to keep an eye on is recommended, especially for trees that are being treated with injectables long term.
Chris:My claim to fame is that scientist from Morton Arboretum visited my ash tree in Macomb, Illinois because I've been getting them injected for several years now. And so they studied the wounds that were being created. And so you're right, Emily. That's why the imetacloprid, which requires annual injections, can create quite a lot of wound wood right there over the years. So that's probably why I personally have turned more towards those every other year injections just because I wanna try to avoid creating as much of that those wounds as possible.
Chris:Yeah. Again, you know, it what chemicals people choose, it's kinda up to them. Imatacloprid is cheaper, which is why I think a lot of people use that one. But I I'm trying to minimize the actual wounds that are being created at the base of the tree.
Emily:Yep. And you talk going to, like, the broader category of wood borers that are affecting our tree species, like you had mentioned different control or different treatment options. Like, planting a diversity of species is also of tree species is also a recommendation, like moving forward. And so if we do have in some cases, you know, we're going to have things that are more generalist. You know, the Asian longhorn borer is going to be it's a little bit more generalist than like emerald ash borer was, but by having a wide variety of species in our landscape.
Emily:Hopefully, if we ever do have to clear cut somewhere or we have to do you know, kinda take drastic treatment options or there's widespread effect, we don't lose all of the trees. That's kind of the theory behind planting a diversity of species in our landscape is that we are hedging our bets against things that are coming our way. So more trees, different trees in all the places. Mhmm.
Chris:That's right.
Emily:Yeah. Okay. My turn. So I hinted that I've chosen one partly based on aesthetics, and so this is it's not a pest. It is a fungus, and it is cedar apple rust.
Emily:So the rust I'm gonna talk about specifically cedar apple rust. We'll be starting to see that here in the landscape. Ken, maybe you're starting to see it already, but we'll start kinda seeing it here up in Northern Illinois in the coming months, weeks and months. The there are other rusts that behave similarly, and so kinda keep that in mind. There's, like, a soybean rust.
Emily:There's a white pine blister rust. Like, they all are similar in their biology. And I think these are really interesting species because they actually require two host plants to complete a life cycle, and so the so cedar apple rust needs a plant from the Caprese family, and so those are things like your eastern red cedar, juniper species, and something in the rosaceae family. So our apple trees, our hawthorns, serviceberries, there's lots lots of things in the Rosaceae family to complete their life cycle. And these plants need to be approximately one mile like, within one mile of each other.
Emily:So I'll get into treatment options and management options here. But I just wanted to kind of denote that that one mile radius, elimination of one of these species is not really an option. I've often heard that with, like, orchards where it's like, oh, if I just, like, take out all the eastern red cedars. Yes. In theory, that's great.
Emily:But the eastern red cedar, if anybody, you know, is familiar with the plant, which probably most people are familiar with the plant, is native. It is a prolific native. It is a hardy native. It does very well in wild spaces, and so it is a little bit unreasonable to think that that is a viable management option for cedar apple rust. Sorry to disappoint anybody, if that is what you are counting on.
Emily:So before I get into that, though, I do kinda wanna run through just, like, the life cycle of this because it does have you know, it requires those two different hosts in order to complete its life cycle. So I'm gonna I if I stumble over my words, there's some interesting I'm not a specialist in fungi, and so some of the words are fun to say, and so just forgive me if I trip over them. But okay. So spores are produced in the spring, so they need to have, like, moist cool sorry. Moist warming conditions.
Emily:And so for cedar apple rest, the the ornamental part of it are the biatospheres that are being produced. They're they're or they're on, like, a a golf ball kind of structure, and then they produce these, like, orange gelatinous appendages that are, I think, really ornamental. They're large in size. Like, when I say golf ball, I mean that they are approximately the size of a golf ball. And so if you have a a heavy infestation, the tree looks kind of decorated, if if you will.
Emily:Like, you can see it from a ways away when everything is in full development, everything is hydrated. I don't know. I'll just pause. Like, you guys do you also appreciate seeing these? Am I the only one that's like, oh, look how pretty they are, even though they're orange, guys?
Ken:Yeah. They're cool.
Chris:Yeah. It's like little aliens landed in the tree and they're
Emily:like Yes.
Chris:Yeah. Checking out the planet.
Ken:Tentacles coming out. Yes.
Chris:Tentacles. Are they called telomeres? Is that the name for the the tentacles?
Emily:Horns is what I've heard. Yeah. Okay. Tilia spores, yeah, are produced. Yeah.
Emily:To produce the the actual fungal spores. And so, yeah, these these horns, like, they'll emerge. Like I said, we need to have a warm, wet spring, and so we're kind of in that in that sweet spot right now. And so I expect that we will see cure coming in the next couple of weeks depending on where you're at in the state. These them hydrated.
Emily:They're already on your tree. They're, like, lying in wait. You can see them in the fall. They're, like, little they kinda look like little cones. They're they're not hydrated.
Emily:They're not developed. They're little brown masses on on a cedar or a juniper is what you'll see these on, not on the apples. That looks different on the rosaceae family. But they're kind of like lying in wait on the branches, and they will hydrate here in April April to May. If we have if we have lack of moisture, they will wait.
Emily:They will continue to wait. And what's interesting about these is that if we if they hydrate, they can, you know, start to produce spores. But then if we, like, dry up and there's the lack of moisture, they will go dormant, then they can rehydrate. And so it's kind of an interesting life cycle in that you could have them kinda rehydrate multiple times in the spring. When we have more consistent warmer, drier weather in the summer, then they they actually dry up and shrivel up, and that is the end of those those golf like golf ball like features.
Emily:So so what happens is, like, when they are producing spores and the spores go airborne, and they are traveling via the wind, and they hopefully land on a member of the Rosaceae family. When they land on an apple or a hawthorn leaf or fruit, it can be on either they'll germinate and they will form like an orangish yellow kind of spot on the leaf of the fruit, and this is where that rust name comes from, is it kind of looks like there's rust on the leaf of the fruit. And and they're smaller in size, you know, definitely not as large as the cedar infestations are. And so you gotta you have to look closely, but there's often a lot of them kind of, like, on a leaf. And so you can you know, just by interacting with your plant, you can see them if they're there.
Emily:And so what happens is, like, this it germinates and it develops, and it actually will run through the leaf, so it's it can land on, like, the top or the bottom on the surface of the leaf, but then as it develops, it it is all the way through. So you can see this rust spot on the top of the leaf or the bottom of the leaf, And it produces this spermata, which is like a it the spermata releases this, like, sticky kind of liquid that is attractive to insects. And so then the insects will come, and they will be carriers of the spermatia from one location to the next, and thereby encouraging fertilization. And when that happens and a fungus grows, produces more spores on the rosaceae family. So it's a acea is what those are called when they're on the rosaceae family.
Emily:Those spores are aciospores. Those are released into the wind. They go back to our juniper species and reinfect the eastern red cedars or junipers, and it starts over again. And it it has to go back and forth. Like, an aces spore cannot infect a rosaceae family member.
Emily:So if it does not find a member of the juniper family, then it it is not it doesn't produce it doesn't develop. So I think that's wild and cool. That's why I chose in part. The galls on the cedar tree, like I said, if they they can rehydrate or, you know, multiple times, but once they are done, then they will they will dry up and fall off the tree. So you oftentimes won't see them.
Emily:You can see them persist a little bit. I've seen them persist a bit, but oftentimes they'll fall off the tree over the course of the year. These are kind of an annual species of rust, and so other rusts can persist and lie dormant for multiple years. This one is more annual in its life cycle, but so other rusts can can lie dormant. So management wise, and is this a problem?
Emily:Well, not really. There's not there's a lot of tolerance within our landscape with the exception of, like, orchards. Apples, of course, are in the rosaceae family, and so there's it can be a problem. It can be result in, like, reduced yields if the infection is large in an apple orchard or if the fruit are blemished. Sometimes that can minimize the marketability of the fruit.
Emily:But it often does not warrant a lot of management in, like, a home landscape to minimize infection, to minimize your challenges in your home landscape. Cultural practices would be just choosing species that have more tolerance to cedar apple rust. You'll see that on rosacea plants. Plant labels, it'll say tolerant. Don't intentionally plant eastern red cedar or juniper plants.
Emily:And I say that because so you don't often have to intentionally plant eastern red cedar. They volunteer to come up. But, you know, for, like, windbreaks and stuff, maybe don't choose eastern red cedar as part of your diverse windbreak, especially if you have susceptible rosaceae plants within, like, a close proximity to it. It's not gonna ever be eliminated. So go ahead, Chris.
Chris:I just planted five Taylor junipers next to a crabapple.
Emily:Can't wait to see what happens there.
Chris:I wanna see what happens. I've I'm like, I'm like, one with Ken on this one. I wanna see what happens here.
Ken:Get some good pictures. Yep.
Emily:Yeah. Yep. And I live in the country, and, like, I've got an orchard. We've got you know, like, we've got pasture land that has, you know, eastern red cedars popping up. Like, it's there's just no way to to minimize exposure or eliminate exposure, but it that's pretty close.
Emily:So you're, like, intentionally okay. Update to come. Good growing. So scouting, you can do scouting. Like I said, the the like, fruits are already there.
Emily:Those galls are already on your junipers or your eastern red cedars, and so you go out and scout for them and remove the galls prior to development of those, like, orange gelatinous structures that can be done in the fall or winter. You're bumping up against the time where they're gonna start hydrating, so if you are gonna do it, do it in early spring. And then there are, like, fungicides are not generally recommended just because of the widespread nature of it and the minimal effect that it's gonna have on our plants. There's some so trees are usually tolerant, and then fungicides for the home gardener are only intended for plants that are not to be consumed. And so if you have, like, a home orchard, the fungicides are not available for use on consumable products.
Emily:So it would be only on your ornamentals. And, usually, we just kinda tolerate plant resistant cultivars or tolerate rust. So yeah, have you guys you guys have seen the orange gelatinous structures. Yeah. We'll insert a picture because they are super cool.
Ken:Yeah. Cedar apple rust is one of those if you're planting apple trees, that's that's one of the big easy one with four resistance, that and fire blight.
Emily:Yes. Yeah. Yep. And there are a lot of cultivars available that have resistance, and so there's it's not like there's just, like, one or two species. This is this is a known challenge cultivars have been selected for and bred for resistance to the both fire blight and cedar apple rust.
Emily:So yep. Alright. Next round. Ken, we're back to you.
Ken:Alright. Then the second one I picked, is bagworms. So they're not necessarily out and about doing a whole lot right now, but we still have time to do something about them if they were defoliating your, needle evergreens or or other plants. So so if if you've got problems with vagabonders, you know what they look like, but they're these caterpillars, they have these silken they'll build these silken tents over themselves, and they will attach foliage that from the plant they're feeding on onto those, and they'll expand as they get larger. So they are emerging.
Ken:Oh, what is it? 600 growing degree days, give or take, base 50, start date of March 1. So, typically, that's gonna be late May, June, for for Illinois. Maybe a little earlier this year given the way things are going, but time will tell. So again, you've got time to get them off.
Ken:Basically, once it gets warm enough, those eggs so those eggs are in the in the bags. So the eggs will hatch. The the caterpillars will crawl out. A lot of times, they will balloon, so they'll spin a silk thread They'll catch the wind. They'll be dispersed that way.
Ken:If they land on a tree they like, they'll start feeding. And as they're small, you know, they may just be rasping the surface. So you get kinda get this light green color on on needle evergreens. And as they get bigger, they'll eventually consume the entire needle. Typically, we think about them feeding on on our needled evergreens, whether that's, you know, like arborvitae and and things like that, spruces and stuff, but they can also get on, broadleaf trees.
Ken:So crabapples, pin oak sometimes. I've seen them on maple trees in my yard again. Not nearly at the level that you see them on on evergreens typically, but they can feed on broadleaf trees as well. I think it was a deciduous plants deciduous woody plants in the 45 plant families will be fed on. There's 125 species of evergreens that they will feed on.
Ken:So but, again, as they're feeding, you know, a few bagworms here and there isn't really gonna do much, but sometimes you get those populations really building up. And I've seen, you know, large mature spruce trees, not completely defoliated, but, like, an entire side defoliated or or close to it. So they can do quite a bit of damage as those populations build up. And like I mentioned, as they feed, they will stick on plant debris to their to their bags. And one way you can tell if something is still actively feeding is if it has that green tissue on those bags.
Ken:If it's all brown, that individual is either is no longer feeding. It could be pupating. It could be dead. For whatever reason, it's not feeding anymore. So that's how you can tell if they're active.
Ken:And if they are active, you could spray an insecticide. Again, the BTK would be a good option because it only affects caterpillars. Spinosad would be another kind of less less less broad spectrum maybe. And there's others that you could spray on trees. But, again, you run into the issue if you've got a large mature tree that's, you know, fifty, sixty feet tall.
Ken:You're probably not getting to the top. You're gonna have to have somebody come do that, for you. So but they can be managed. Once they pupate, they will begin to pupate inside the bags. The females will not leave those bags.
Ken:Males will emerge. They'll go out. They'll mate with the females in the bags. Females lay eggs, die within that bag. So those eggs are in in that bag with the dead female, and they will emerge kinda late spring or early summer.
Ken:So if you've had issues with these, we can go out and and pick those now still and get those off your plants and clean those up. When you are handpicking, don't just throw them on the ground because those eggs are still in there potentially, and they're going to hatch, and they will still get on your plants. So smash them, collect them, get them out of your landscape, destroy them, get rid of them somehow. How you how you choose to do that is up to you. But get rid of them so they're not still not hatching, and infecting or attacking, your plants.
Ken:I did run across some stuff. There is a parasitoid wasp that will parasitize these, and it was a accounts for seventy six percent of the parasitism parasitism observed in bagworms in one study. And there was a 2005 study where the the parasitism exceeded 70% in bagworms, infested plants that were near a a flower bed, but only 40% of those bags were infested if their flower beds were further away. So plant flowers, draw in those parasitoids, draw in those predators, and they may do they will do some management for you. So, hopefully, your populations don't get too high and out of control.
Chris:Ken, I we go out to eat at a particular chain restaurant where you can eat outside, and there are some evergreens near this table, and this poor evergreen is just coated in bagworms. But I even saw they made their bags on the the leg of one of the table. And I'm like, well, that's wild. There's so many. There was they're out of room on the plant or something.
Chris:I don't know. But it there was this little pupil case thing that was stuck on the leg of the table.
Ken:Sounds like a healthy healthy population there.
Chris:I think so.
Ken:On the plant.
Chris:As everybody's eating, I'm, like, pulling them off the thing and, like, opening them up and looking at the little caterpillars inside. They're like, oh, gross. Like, so neat.
Emily:Well, they okay. So this is something perhaps only I got confused in my brain when I was learning about these. But to me, like, it looks like they're stationary, but they're not. Like, they actually build the, like, the bag kind of, like, around the back of their body, and their head is still exposed. Like, that's how they they can move like that, Chris.
Emily:Right? Like,
Chris:Mhmm. Maybe
Emily:I'm the only one that was like, they're just, like, right there on the tree, but they actually are able to move around until they pupate.
Ken:Yeah. They'll crawl around. Like, you can open up those bags and pull the caterpillars out. They're not particularly happy with you when you do that, but yeah. They'll they'll move around.
Ken:I've maybe we could throw some video. I've got some video. Like, then, like, when you get close to them, they'll they'll hide in that bag. But if you're patient, eventually, they'll come out and you can watch them Mhmm. Feed and stuff.
Emily:You guys have interesting hobbies. Kinda like you. That's really cool. They're they're neat to see, and it's nice that it's easier to to control than some of our other pests. So good activity for children.
Ken:Yeah. Assuming you don't have a large mature tree in there. The bags are 30 feet in the air. Those are a little more difficult to manage. Yes.
Ken:Yeah. Don't put your kids on step ladders or
Emily:Please don't. Nope. That is not what we are recommending here.
Ken:Yeah. Go rent a scissor lift.
Emily:Not really. Don't do that. Let
Chris:them play with one of those. That'd be great.
Emily:I did think when you were talking about control, I wondered if this is where fire is useful when you collect those, if that's
Ken:Yeah. If you wanna yeah. You had a, you know, bonfire and you collect them, toss them on there, or smoosh them, or bag them up and get them out.
Chris:Do they go well in s'mores?
Emily:Oh.
Ken:I'm I'm not sure about the edibility of these or not. I'll
Chris:Everything's edible once. Right, Ken? Yes.
Emily:You go first.
Ken:Yes. Probably the next next one we do our grow along taste test, maybe we'll find salmon.
Emily:Okay. Well, let's move on. Chris, what do you have for us?
Chris:Well, let's stick maybe in the the vein of, you bagworms if they affect spruces a lot. Yeah. I mean, they go after other plants as Ken mentioned, but let's go to some needle cast diseases. So this is like a suite or a group of diseases. And and even when we sort of boil it down to a particular disease that that affects our Colorado blue spruce here in Illinois called Rhizosphaera.
Chris:Rhizosphaera is a genus of many different species. Rhizosphaera is sort of found worldwide. It's it it is documented, but not very well. In fact, there is a and maybe it's arguable, but I think pathologists have said that the particular species that they find most often on Colorado blue spruce infecting the needles and killing the trees, which is Rhizosphere called coffee. That might be a native disease.
Chris:Some say it is. But but we need to kinda maybe catalog it around the world because they can find Rhizosphere all over the planet to know, you know, where did it start. And right now, pathologists like, hey, we think it started in North America or maybe at least the Midwest. So the the Rhizosphere, the way it operates is it will infect a spruce needle. Primarily, the host is gonna be Colorado blue spruce.
Chris:And it gets into the tissue of the needle. It's a fungus. And as the fungus fungus grows and then goes into sort of its fruiting or flowering stage, not really flowering, but it's releasing its its spores. This pycnidia develops in the stomata of the leaf. I just said two complicated words.
Chris:I had to look them all up, you know, but but this pycnidia, it's this this black sphere that just comes into the stomata of the leaf, and the stomata is the pore that exchanges air between the plant leaf and the atmosphere. It's how plants breathe. So when that fungus clogs that spore, it's essentially making it so that the plant cannot breathe. It can't exchange air into the atmosphere. And we have hundreds, if not thousands of stomata on a single needle or leaf for a plant.
Chris:And this takes up maybe a year or two for really that infection to to make it so that it will impact the the health of the plant. But after about a year or two, those stomata on those older needles get impacted infected, and they'll die and they'll drop off, which kind of gives us this like lion's tail effect. So we have green living growth which is still could be infected, but it's not dead yet, hasn't quite gotten suffocated yet. And then all the needles behind it on that branch are dead falling off. So it's that lion's tail look.
Chris:Very often, this rhizosphere starts from the bottom of the shrub and moves its way upward, but I've seen it go from top to bottom. It's kind of wherever that initial infection takes place. And for the most part, they're spread via water. So splashing water, rainwater, any of that is gonna spread those spores, but they can also be moved on the wind through through high humid environments or on other insects, birds, whatnot going from an infected plant onto a healthy plant. Like I said, Colorado Blue Spruce is their primary host.
Chris:So if we wanted to still have an evergreen, a spruce particularly, that had some resistance, we could go with white spruce, Piscea glauca, think that's what that is. But there still has some susceptibility even with with that particular tree, white spruce. When you again, when the plant gets stressed, they can get sick. So if you want a a very resistant but not immune plant, Norway spruce by cea alde aebes is gonna be your your go to for that one. But again, they've seen Rhizosphaera, in fact, highly stressed Norway spruce as well.
Chris:And that's why I always turn again to that eastern red cedar. That's why I planted junipers right by the crab apple tree. So anyway, some things to look for is that you can actually scout for this out in the field. If you have see an affected branches, you want to go to the ones that look sick because if you go to the dead needles, we also have rot fungi that will also colonize those stomata and it will be hard to be like you can't conclusively say like, oh yes, Rhizosphere did this. Whereas there might be a rot fungus in there just decomposing that needle also.
Chris:So find a somewhat sick needle, something that looks like it's been infected, you turn that over on the bottom and a healthy needle has white stomata. So good air exchange is happening there. An infected needle is you're just gonna see these black dots filling up these little stomata. And that's a really good way to diagnose that this is indeed rhizosphere that's impacting this plant. There's another look alike called stigmina needle blight.
Chris:For a lot of time, I think they lump these all together, but they determine it's a totally different pathogen. So yep, you can go online. Stigmina has these like tendril like appendages that it that make it look a little bit more dusty on that bottom side of that needle. Whereas rhizosphere is sort of more just kind of rounded where that fungus is growing inside that stomata. You can see this if you have good eyesight with your naked eye, but most people probably gonna need a hand lens to see it, microscopes even better.
Chris:The other thing for if we talk about treatment so treating Rhizosphere, obviously first thing, don't plant Colorado Blue Spruce. Hey, then you don't have to worry about anything else from there on or cut down your your Blue Spruce and plant something different. If you want to try to preserve your Colorado blue spruce, it's gonna require two very timely applications of fungicide containing your active ingredients can be chlorothalonil or Mancozeb or a copper based fungicide. And it's gotta be when those needles you gotta be out there every day scouting when those needles are about halfway extended out of their bud for that year. So you're looking for this year's growth when those needles are halfway grown, half the size of the last year's needles, that's when you apply your fungicide.
Chris:And then you come back like three to four weeks later and do a separate separate application just because that's gonna protect those needles from getting infected as they're expanding, and they're not gonna get that fungus on them through any rainfall, humidity, things like that in the springtime when that disease is gonna be most active. So so, yeah, Rhizosphaera needle cast. It's a fun one. And, you know, Illinois Extension has basically said recommended to stop planting blue spruce because of it.
Ken:I said those fungicides are only gonna protect too. So if if you got infected stuff, it's not gonna cure it.
Chris:So Yes.
Ken:You have to keep on top of it if you wanna continue having healthy foliage.
Chris:Yep. Oh, and and read those product labels very carefully. Chlorothalonil, if you apply that at too high a rate, will burn your foliage. So you, you know, follow those rates very closely.
Emily:Well, you said about planting different spruce species. So the challenge with that, like, you know, we're not recommending planting blue spruce really throughout Illinois, but they are not of the same size and form. Right? And so, like, Norway spruce do not replace Colorado blue spruce in the landscape for, like, that columnar, kinda compact, a little bit smaller, relatively speaking, size. You know?
Emily:Norway spruce can get really large. I love seeing mature Norway spruce in, like, a windbreak, but they're big, like, sweeping branches. Like, they're they're very majestic, but they are not the same as Colorado blue spruce. So that's sometimes disappointing for folks. So Yeah.
Emily:Yeah. I think an alternative would be, like, a fir. I I tend to go with as an alternative to to Colorado blue spruce. Well, I'll wrap it up here with a doozy, and it's oak wilt. So I get questions about oak wilt a lot.
Emily:You know, we're just really going out with the bang here. So oak wilt is a vascular fungal disease of Quercus, actually, Fagaceae family, but our oaks are most susceptible to it. It is fatal. And so, essentially, I've heard it described as, like, the Dutch elm disease of oaks, and so it kind of operates in the same way in that when a tree is infected, the vascular pathways, so the xylem and the phloem, which are the tubes essentially that exchange water and nutrients from the top of the tree to the base of the tree are clogged up, and so they are no longer functioning to transport nutrients and water between the root systems and the canopy of the tree. Hence, like, the name wilt is because those symptoms, like, the resulting symptoms look similar to what wilt might look like when it's, a drought situation.
Emily:Like, it's it's it's cutting off of the of the moisture supply. So we don't exactly know where oak wilt originated. So it was discovered in Wisconsin in 1944, so we have had many decades knowing about oak wilt, but it is not believed so we don't we don't exactly know if it's native to North America or if it was introduced. There are some that believe because of where it was originally found that perhaps it was it is native. It lied dormant, you know, when it was kind of it had a boom experience based on climate changes, cultural practices, you know, ecosystem composition changes, and so it it was an opportunistic fungus that perhaps took off.
Emily:That's one theory. It also that, I guess, is also supported in that, like, traditionally, we find imported biotic diseases and pests by port areas, so they are coming into the country at different ports. And if you're familiar with Wisconsin, there's not a lot of ports, like major ports there, and so a little bit more isolated than, say, like Detroit was for emerald ash borer. So that kinda leads some people to think that maybe it is native. More of the consensus and and what we're more researchers are kinda going with is that it it has been introduced to North America, potentially from Central Or South America, just because of it being so fatal to our oaks.
Emily:There's no natural defense, and you would think that if it was native to, you know, ecosystems, that there would have been some sort some level of resistance to it in some, maybe, species of oaks, but it's not been shown to be the case. It's it's highly fatal to all of our our native oak species, and so kind of the consensus is that it was imported. But we don't know when, we don't know from where. I say all of that because I think it's fascinating. We're living with it, and so it doesn't exactly, like, matter now that it's here and we're dealing with it in our landscape.
Emily:And so like I said, it is a vascular fungal infection of oak trees, both in the red oak family and the white oak family are both susceptible to oak wilt. The way that it so the way that it gets into trees and so, like Dutch elm disease, had said, you know, infected oak or infected elm trees, and that was it was less it moved a lot slower or excuse me. Oak wilt moved slower because of the transport, like, of how it is moved from from tree to tree. Like, Dutch elm was transported by wood borers, and they did not need to have they were not opportunistic. They they would create their own wound, they would infect a tree on their own.
Emily:Like, they would bore into the wood and into the cambium layer and infect a tree. 90%, approximately 90% of the insects that are moving oak wilt between oak tree to oak tree via that vascular system, kind of the I don't wanna say juices, but I can't think of anything else. Like, these I will say it. Yeah. I don't want to, but I will.
Chris:These are juicy trees.
Emily:Well, the sap, you know, the sap of the tree. Like, they they insects need to have access to the sap of a tree, and so they are gaining access to it through a wound that is created on the tree. And so when a fresh wound is created, it exposes the sap, and it sends out these volatiles, which are, attractive to insects. And so when you have a fresh wound on a on an oak, insects are being, kind of attracted to that wound, becoming, infected, and then transferring it over to another oak tree that also has a fresh wound. And so most of the insects doing that are moving that way.
Emily:So that's one way a tree can get infected. The second way a tree can get infected, and this is what keeps me up at night, is that they are moving through the vascular systems via root grafting. So when you have colonies or when you have large populations of the same species of tree, a lot of times root grafts will happen, and this is a fusing of roots underground. Like, when they encounter each other, they just kind of, like, fuse together. I think of it like kind of like a street system in, you know, underground for the trees.
Emily:Like, streets will intersect, And they're interacting, and you can kind of go in any of the directions at these grafts. And so the vascular tissue is transporting water, nutrients, and potentially this fungus from specimen to specimen. And so that's gonna be happening underground, and you can have a whole colony or a whole, you know, kind of established planting get infected because one tree was the epicenter for that infection. And I've heard it described as a circle of death in that, like, there it kinda can concentrate yeah. And so, like, there's just, like, this kinda, like, die off of of trees kind of around the original site of infection.
Emily:Decline happens pretty quickly, especially in the red oak family. Trees can can fail quite rapidly within a matter of months. Red oaks can can go from being healthy, robust trees to being being dead. White oaks decline a little slower, but it's also still fatal to white oaks. The symptoms, can lab testing is recommended to confirm oak wilt.
Emily:And I'll talk about how you would take a sample and submit a sample because there are particularities that we need to be conscious of when we're submitting a sample. But if you suspect your tree has oak wilt, it might look like having the outer reaches of the canopy showing so that would be the top of the tree or the lateral branches kind of in late spring, early summer turning pale green or having around the leaf margin, you're gonna be having, like, die back. It's gonna turn brown. It's gonna have It's not gonna be as healthy and robust. That is because of that clogged vascular system.
Emily:Water is not getting out to those those outer reaches, and it will progress over the season in the form of defoliations, sometimes losing the entire canopy by the end of the summer, and so especially, like I said, in those red oak groupings of trees. And then you can also see black fungal mats on the bark. This is where the fungus is developing and it's producing spores, so pressure builds kind of within the tree, and it will break the bark, and a fungal mat will develop. And you can see that happening on twigs and bark. So if you're going to submit a sample, here are some key points.
Emily:So you need to make sure that the lab is ready to receive your sample, so be in communication with the lab prior to taking any of the samples, because the viability of the fungus declines rapidly once it's removed from the tree, so once your samples are taken, the viability re declines quickly. And so you wanna make sure the lab is ready for you. So calling, you know, or having a way to get it to the lab really quickly, whether that's overnight shipping or delivering it yourself. Make sure you have all that organized. And then you want to take three to five fresh cuts.
Emily:This is from wood that is showing symptoms of oak wilts. You want them to be six to 12 inches in length, and it's gonna be one to two inch diameter branches that are selected. They need to be kept cool, like, immediately, and so you wanna have, like, ice packs or dry ice that you can put the the samples on. And like I said, you need to keep it cool until you get to the lab. So, otherwise, they'll get to the lab, and there will be no positive test.
Emily:It will be not because it's not there, but possibly because the sample just wasn't viable. Prevention is gonna be our best defense to oak wilt, so we want to make sure that we are pruning in the dormant season. That's because we are going to have less insect activity during that time. If you do have to make a cut or if trees are wounded during the growing season, apply a latex based paint to that wound within about ten, fifteen minutes of that wound being created, if you can. I try to bring levity to the situation by telling people the color of the paint doesn't matter, and so you can paint it whatever you want.
Emily:But we want to really try to avoid pruning during the growing season. Sometimes, like I said, storm damage will happen or, you know, incidents will happen. We need to to make corrective pruning, but we wanna avoid the spread as much as we can. Once you have it, then there's some pretty drastic, you know, trenching can can be done to try to prevent the spread through the root systems, but then we still have insects to account for. So I don't love ending on this one.
Emily:This one is scary because oaks are such vital parts of the ecosystem. You know, they're majestic, wonderful specimen, but we need to be aware of white oak or of oak wilt. Excuse me.
Ken:And for the painting, this is really the only time you want to paint tree wounds or anything?
Emily:Oh, absolutely. Yes. Thank you for saying that. Yeah. We this is the only time we're gonna be putting any sort of wound treatment on on tree wounds is is to prevent hopefully, to prevent the spread of oak wilt.
Emily:Excellent point, Ken. Look at you, tree guy.
Ken:I'm getting there.
Chris:One other thing. I I know some folks we have oak wilt in our neck of the woods and some folks have asked other tree care companies, nurseries about, you know, what can I do to treat my tree? Is there a chemical? There are some companies that will inject with propiconazole, but it is a, again, a preventative. So if you see it, it's too late.
Chris:But the problem with propiconazole, there's a few issues, is one, it's very expensive because you need a lot of product to treat the large these large oak trees. The other thing is that because it is systemic, that means that pest is being exposed to that fungicide constantly, which then gives greater opportunity for resistance to occur. And so if you do wanna do a preventative treatment with propiconazole, it better be an oak tree you really love. Because if once we get resistance build up in a community, propiconazole is not gonna work anymore. So don't we don't wanna treat every single oak tree in our landscape.
Emily:We had a locally, we had kinda like a mass extinction event. You could see this is kinda back when Oak Wilt was was kinda new to the area and and lost a golf course, lost dozens, I'd say, hundreds of trees. It it it's devastating. It's devastating. And so prevention's the best method.
Emily:But, yeah, we don't we certainly don't want any sort of resistance built up. Alright. Anything else? This was a long episode, but I think we covered a lot of really good topics.
Ken:Thanks, guys. Did.
Emily:And, Ken, you you hung with us the whole time. Good job. We're we're
Ken:not done yet. Yeah.
Chris:Alright. Here. Let's go. Wrapping up. Time to close this puppy.
Chris:Well, that was a lot of great information about this, like, a handful of biotic issues that our trees face. Again, a lot of this is kind of secondary cause. Not all of them, but many of them secondary cause to environmental stress. Well, the Good Growing podcast production of University of Illinois Extension edited this week by who's editing this week?
Emily:Me? Someone.
Chris:I'll edit. Someone will edit. Emily might. We're trying to we're trying to bribe Emily into editing podcast episodes, but we'll see. Edited by somebody.
Chris:Kenilief, editing or not editing, thank you for being here once again to chat about the the biotics of the tree world issues that we see.
Emily:Oh, it's always my pleasure to be with you guys. How about we do some more tree stuff, like always? This has been fun.
Chris:Well, you got my vote. I don't know if Ken's on board or not, but Ken, thank you for also hanging in here. Hey, we got some bugs in there today, so we're we're trying to accommodate all three of us here.
Ken:Yes. Thank you, Emily. We we can do more trees. I don't know about all the time, but we can do more. And, Chris, thank you.
Ken:And we all doing this next week? Let's do this again next week. All of us, some of us.
Chris:All all those in favor, say by I. So, yes, we shall do this again next week. All of us. We're talking trees about this, I think. Don't know when this podcast episode is coming out.
Chris:Boy, you've caught us on quite a date, everybody. But we're gonna
Emily:be Welcome to the Yes. Welcome to spring.
Chris:It's 80 degrees today. I don't know. Is it spring? I I it's hard to tell. But, yeah, good growing.
Chris:We'll be back next week with more horticultural hijinks. Listeners, thank you for doing what you do best and that is listening. If you watched us on YouTube watching, and as always, keep on growing.
Ken:University of Illinois Extension.
Chris:One
Emily:more time.
Chris:Nope. Never mind. Gal, now he's gone again. Here we go. Oh, meow.
Chris:Meow. Meow. Okay.
Emily:He's frozen.
Chris:Ken? No. No. No.
Ken:Oh, no.
Chris:Or is he just standing really still?
Emily:I'm doing
Chris:You holding still, Ken? Are you there? Are you holding still? What's happening?
Emily:There you are.
Ken:Everything froze as soon as you send meow.
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