Insects and Other Pests: Challenges Facing Michigan Woodlots

March 9, 2022

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Video Transcript

 - [Lyndon] My name's Lyndon Kelley. I work for MSU Extension and I'm your moderator, or trying to be your moderator today. Thank you to GreenStone Farm Credit Service and the North Central SARE Program, along with Mark Wolbers and The Alaskan Pioneer Fruit Growers Association. Today, we're talking for the second half of the presentation from Dr. McCullough out of Department of Entomology, working in the forestry area. We just finished up a presentation heavily based in insect pests. We got a couple questions to clean up about how you get an injector, and the second flush of leaves, whether they're victims of the gypsy moth. And then we're gonna move into what, Dr. McCullough? - Well, we're gonna talk about things that do harm to oak trees, some of which are kind of minor and some of which are not minor. So, most of the next chunk of material, we'll focus on oak wilt, but there are some other problems that can look a lot like oak wilt, so we'll get through those first. And then to answer those questions, the first question about whether gypsy moth caterpillars will feed on the second set of leaves that hardwood trees put out, they will not because they will have spun their cocoons and pupated, and it takes the trees a couple of weeks, sometimes three weeks, to put the second set of buds and leaves out. And so the caterpillars will be gone before that happens. So the trees should be okay. And then the nifty little injector device, the one I showed, is sold by a company called Arborjet, and it's a great device. It's a hydraulic injector. So you carry a little canister of compressed air, a little tiny tank, and you don't have to try to force the material into the tree and so forth. It's not cheap though. I think it's somewhere between about 1,200 and $1,500 for that injection device. So that's one where if you're not a professional arborist, it's probably worth your while to hire a professional arborist to do those treatments. Any else, Lyndon? - Thank you. Nope, I think that's it. What's next? - Okay, well, let's talk about some oak stuff. Everybody's got oaks. If you live in... let's see, there we go. If you live in Southern Michigan, chances are you have oaks on your property, and we're gonna talk about a few of the problems that oaks encounter and really focus a lot on oak wilt. And I thought it would be useful to make sure we're all squared away on red oaks versus white oaks. If you look at the leaves there, there are different kinds of white oaks, okay? There's white oak, Quercus alba, but there's also bur oak and swamp white oak. And if you look at the leaves, they all have those rounded lobes, okay? Whereas the red oaks, including northern red oak, and northern pin oak and black oak, they have pointy tips on their leaves, okay? That's not a real scientific nomenclature, I guess, but it works for me. And then if you look at the bark on red oak trees, I don't know how to describe it exactly, but you will know it when you see it. Whereas white oak trees, they always look kind of chunky, a little kind of square chunks of bark there. So some of the pathogens that we talk about, in fact, oak wilt, in particular, is much more important on red oaks than white oaks. That's why some of this is important. We'll start with a kind of minor one, oak anthracnose, is a fungal pathogen that affects the leaves of white oaks, okay? You don't really see this on red oaks. And you will look at the leaves and they just look bad. They look nasty, you know? Sometimes it looks like maybe a leaf mining insect got into the leaves. But in fact, this is dead tissue. It's being killed by a fungus. Sometimes the leaves can look a little bit shriveled. It's not uncommon to have a lot of leaves drop from the tree late in the spring or first part of summer. And you may get that same response that we talked about with defoliation, where the trees may have to produce another set of buds in some cases. This is not that big of a deal though, frankly, and if you have trees that are along a river, I know there's trees on campus along the Red Cedar River and they get this every year. Really not that big of a deal, but it's something to be aware of. Armillaria root rot is very much a secondary pathogen, okay? This is only gonna be relevant if you have trees, typically, that are very stressed, could be a couple of years, a really bad drought, something like that. And it is in the soil, it's a fungus in the soil, and the trees typically die, not necessarily over a single year, maybe over a couple of years. What you look for is down at the base of the tree, you have to chip away the bark, like you see here down at the base of the tree, and you'd see this white fungal mat down here. And then not always, but most of the time, you'll see the black shoestrings. The other name for this pathogen is shoestring root rot. These fungal hyphae things will grow up the base of the tree, and into the soil and so forth. And the fungus can live in stumps of trees. So if you have a stressful situation, you have some fresh stumps, that armillaria can sneak out, and it'll go about six to nine feet and can infect some other trees. This is not common. You know, usually if this is going on in a stand, you know that you have other problems in that wood lot or in that stand. The reason I wanted to mention it is that if a tree dies of armillaria, it can start to look a lot like oak wilt. And this might be a case where you want to have somebody come in and help you look at the tree. There's the forestry assistance program that has foresters that can come do this. CISMAs, you're gonna hear about that in a little while. There are consulting foresters, somebody that knows what to look for and how to look at the tree. That can be helpful, okay? And we're gonna talk about two-lined chestnut borers. So, armillaria is a disease of really stressed trees, and two-lined chestnut borer is an insect pest of stressed trees. I wanted to put oak decline on here. There's a joke that forest pathologists, and I am not a forest pathologist, I just play one on TV sometimes, that people talk about declines when they don't know what else to call it. But there really is something that is oak decline. And it is where you see trees and part of the tree, or even the whole canopy, will start to brown up in the summer, usually late in the summer. And those dead leaves stay on the trees and so forth. And the trees don't die. Decline is the trees get more and more and more stressed. They become less vigorous, and eventually something is probably gonna kill them and it might be armillaria, or it might be two-lined chestnut borer, or a combination of the two. Not much you can do about this. This usually has to do with growing conditions, might be drainage if the water table has changed or roots have been cut, anything like that. It's just a thing that happens. And this is a picture that the DNR gave me, an aerial shot. This is up in Manistee County, and you can see all those dead trees, and those red trees that have recently died. This is a big area with oak decline, okay? Mature oaks, in this case, it's mostly northern red oak with a little mix of pin oak in some of it, there's not much you can do about a case like this. You know, at some point you're gonna have to take those trees out of there, and then do some silvicultural work and decide what that stand is gonna be because obviously the oaks are gonna have a tough time. There may be a little bit of oak wilt mixed in there, but you can't tell because there's just so much oak decline. So oak decline is something to be aware of. It's not something you could do much about, just something to kind of have in the back of your mind. I put this in because there was some areas that had a lot of oak skeletonizer last year. Again, it's a tiny little moth, the insects skeletonize the oak leaves. They actually feed on the foliage in between the veins on a oak leaf. There's two generations of it. And by the end of the summer, you can have some nasty-looking oak trees where these leaves, when they're skeletonized, all that's gonna be left is brown leaf matter and it's gonna be mostly veins. And I showed you this on the hemlock trees. These little, tiny caterpillars will spin these little, tiny cocoons where they pupate. And these will be on the leaves of oak trees, but they will also be on... I showed you hemlock, where they just kind of wandered over there and pupated on a hemlock tree even though they don't feed on it. You'll get cocoons. A lot of times I see them on screen doors or windows screens, something like that. Not that big a deal, native insect. We usually have a couple years with lots of oak skeletonizer and then it goes away. And then two-lined chestnut borer, this is the other probably most common pest of really stressed oak trees. It is a close relative of emerald ash borer, but it will only attack oaks. And it's usually going to be on red oaks. Once in a while, maybe a white oak, like a swamp white oak, but it's mostly red oaks. You have adult beetles that you'll probably never see. They're very small, little things. They are attracted to the volatiles that are produced by stressed oak trees, particularly ethanol. The females only lay a few eggs, you know, like half a dozen eggs, individual eggs on the bark. The eggs hatch, the little larva go right through the bark, and they are gonna feed in the phloem, that's the inner bark, okay? Right under the outer bark. So if you peel off the outer bark, you're gonna see galleries, much like you might see on a ash tree with emerald ash borer. You might see the little, white larva in there. And they do the same thing to oaks that you would see on a ash tree with emerald ash borer. They're going to interrupt the ability of the tree to carry nutrients down to the roots and to carry water from the roots up to the canopy. And what you will see when you're looking at a tree is usually some decline that happens over time. So you get a top-down dieback where you have dead branches up high. You may have some infested branches that die late in the summer, kind of in the middle of the canopy. And then down here, there's no insects feeding so that part of the tree stays alive. Kinda like armillaria, the dead leaves stay on the dead branches with the dead tree into the winter, just like you would see with a normal oak. You will have to look to see if the galleries are there under the bark. And rarely do we see trees die from two-line chestnut borer in one year. A lot of times, there's some dieback up at the top and then conditions get better, the tree tends to recover, and it improves. Every once in a while though, you'll see some trees get killed by two-lined chestnut borer. A couple things to keep in mind here, and this pertains to two-lined chestnut borer, and even more generally, is that if you are working in a wood lot, and if you do some thinning or you take out some trees, you do some harvesting, and you leave some trees behind, and you leave some oak trees behind, those trees are going to experience extra stress for at least a year or so. And eventually they will recover and they will respond by bigger root systems. They will take advantage of that extra light and nutrients and water. But when you open the stand up, when you reduce the number of trees and the canopy cover in a wood lot, for example, you're increasing the sun and the wind, and that increases evapotranspiration. And that is kind of a stress for those trees. So you gotta be careful if you're having, say, a gypsy moth outbreak, that's not a good time to go in and do some thinning, or to do some selective harvesting, where you're gonna leave trees behind because now you're leaving behind very stressed trees. As far as wood lots and forested areas go, the idea is just mostly to keep the trees healthy. Again, don't give the trees a double whammy where you're stressing them with a harvest or a thinning operation during or just after they have been stressed by defoliation. Keep the roots healthy, don't compact the soil, that sort of thing. Sometimes we talk about salvage cuts. I know where we've had straight-line winds, for example, there's been salvage cuts where you go in and try to take the valuable logs out, something like that, anything to reduce the amount of material that's available for two-lined chestnut borer. And then with urban trees, again, it's mostly about keeping the trees as healthy as you can. If you're going to prune dead limbs that have died the previous year, do it in the winter, or maybe this time of year because the larvae are over-wintering in those branches. And so you prune the branches off, and chip them or burn them, and that will kill those insects before new adults can come out and lay new eggs. And you can always use a systemic insecticide like the emamectin benzoate that we use for ash trees. It's gonna give you three years of two-line chestnut borer control. Okay so, unless anybody has a burning question, let's hit oak wilt because that's a thing. And a lot of publicity, a lot of people talking about it. A lot of people have contributed to the slides I'm gonna show you here. This is Monique Sakalidis, the pathologist who probably should be talking to you today, but she had a baby a couple months ago, so she's on maternity leave. And then James Wieferich over here is the forest health guy with the DNR that handles most of lower Michigan, and he works a lot with oak wilt and so forth. Oak wilt is a vascular disease. It affects the ability of the tree to move water. It's caused by a fungus. You can see the name here, Bretziella fagacearum. And it is only going to be in the xylem tissue, okay? That's the sapwood, and those are the cells, that outer part of the sapwood, is what is carrying water through the tree. When a tree is killed by oak wilt, it will either, typically, the next spring, it will produce something called a pressure pad. And a pressure pad, all of this is happening under the bark. It is where the fungus forms a mycelial mat and it makes spores on this mat. And because the mat is pushing outward on the bark, you get a crack in the bark and that's the pressure pad. And we show you a lot of pictures of a pressure pad and a mycelial mat after we have taken a hatchet and removed the outer bark. But really what you see on a tree is something like this, okay? It's just a crack in the bark. If you chip away that bark, you would see the mycelial mat with all the fungal spores down below. Red oaks are the only ones really that are gonna be affected by oak wilt. I shouldn't say the only ones, but with white oak, you just don't see the symptoms progress. You might get a little bit of dieback or decline, but nothing like what happens with red oaks. Nationally, we know oak wilt is in Texas and the Midwest, the upper Midwest, and some of the Eastern states. It acts like it's an invasive pathogen. But we can't really actually confirm it's invasive because nobody knows where it came from. There's a thought that it moved up from Central America where a lot of the oaks evolved, but nobody's been able to find it anywhere else outside of North America. In Michigan, we know we have oak wilt in 54 counties at least. That doesn't mean that oak wilt is everywhere in those counties, it means it's been confirmed at least once. And obviously the value of oak in terms of timber and wildlife, and all kinds of things is really important. Now, oak wilt is vectored by nitidulid beetles. These are tiny, little beetles and all they wanna do is feed on sap. They're attracted to really sweet-smelling kinds of things. If you wanna trap them, sometimes you can put a pie plate with beer and a banana in it, okay? Or a banana peel. Anything sweet and kind of smelling like that will attract them. They're also called picnic beetles. Some of you might have heard that name. These are two nitidulid beetles on Olivia's hand and they are mating, okay? So that gives you an idea of how tiny they are. One of the things they are attracted to are those pressure pads because the pressure pads are producing compounds that go into the air, volatile compounds, the beetles track those compounds, find the pressure pad, get in there, and literally roll around and feed on the fungus, and mate on the fungus. They're just having a great time. When they leave that pressure pad, they're still looking for sweet things to feed on. And if you have a healthy oak that has a wound and that the oak tree is producing sap from that wound, they will go and feed on the sap. And because they've been rolling around on that fungus mat, they take spores from the fungus, introduce it into the healthy tree with the wound because they're feeding on the sap, and that's how new trees become infected with oak wilt. That is called overland transmission. All that means is long-range transmission, okay? And what happens is you have a dead red oak, right? Check this out, this is pretty cool. And it forms a pressure pad. So the nitidulid beetles are attracted to it. And then they go to a healthy red oak that has a wound deep enough to expose the sap wood, and they vector the fungus and now you have another wilting tree that's infected. And usually we're talking about one or maybe just a couple of newly infected trees that are caused by this overland spread, the insect vectors. The problem is that once you have an infected tree, then the fungus can go... It will go down into the roots, okay? And red oaks are notorious for root grafting with each other. And so the fungus can spread from the infected tree's roots into the roots of other healthy trees through these root grafts. And that's how you get a oak wilt infection center, so you end up with dead trees, and then dying trees, and then healthy trees that may be becoming infected via these underground roots. And there's been estimates at how fast the fungus can move, but it depends on where the root grafts are, who's grafted to who, what kind of soil there is, and all kinds of things. So again, this is an oak wilt center. You can see really dead trees in the center and then it expands, and you get newly infested trees, or trees that have died more recently out on the edges, okay? So this is what pathologists do, they have the disease triangle. They're very fond of their disease triangles. And we have a host here, we know it's gonna be red oaks. We have the pathogen, it's the fungus, the Bretziella fungus. There are climatic and environmental factors, okay? Temperature, moisture, soils, and so forth. We know we have the insect vectors that can transfer the fungal spores from an infected tree to a healthy tree. And what we wanna know is what is the high risk period for overland spread for these insects to vector the fungus into new trees, and start new oak wilt infection centers. We did some research over the last few years, we worked on state forest land with the DNR that we knew we already had oak wilt present. In part of the stand, we didn't wanna start any new oak wilt centers. So we had three sites the first year, four sites, we added this one the second year, and this is what the pathologists were doing. They wanted to find out when red oak trees are susceptible to infection, and when those mats with the spores can be produced during the year. And so this is Karan Chahal here. He's a PhD student who works with Monique. Monique and Karan inoculated a red oak tree at the three sites with two million fungal spores, or they had controls where they just... You see them inoculating right here. This is Monique. They just shot water into the tree. And they did one tree at each site once a month, every month from March to November, for three years there. And then they looked at the trees. We checked the trees every couple weeks to see who was producing pressure pads. And Karan was looking at other sites with the DNR, looking at my mycelial mats and the pressure pads and so forth. So to give you the short story, when trees were inoculated, artificially infected, anytime between late March and late September, they became infected and died from oak wilt. If you inoculated the trees between mid-March to mid-July, the trees died that same summer. If you inoculated them in late summer, say, anytime from August through mid-September, the trees died, but not until the following year. And then if you inoculated the trees late in the fall, no leaves on the trees, you know, no living leaves on the trees, they're not really moving water much up to the canopy, those trees did not die, okay? And then in terms of when those pressure pads, you know, with the mycelial mats underneath them, Karan looked at 226 trees that had mats on them, collected them, took them back to the lab, did all kinds of things to culture to the fungus out. And as we suspected... expected, I guess, most of the pressure pads, the mats are gonna be out there in May and June, and then there's a big drop in July when it gets really hot and dry. The moisture level in the wood is simply not adequate for the tree to produce these pressure pads. And then there's another little blip that comes late in the summer, and then it kind of dies out over the winter. So now we look at the insects that vector the pathogen, okay? And which species are out there, when are they active, how many, what percent are contaminated with the fungus? And I'll tell you a little bit about this xylem development too. We'll save this last one for another time. But the way we monitor these beetles are with these funky, little traps that we build out of PVC pipe with a little glass vial here. And this is a little piece of flange aluminum that lets them move in the wind. And we put those traps out by mid-to-late March or early April. I left them out there through October over two years. And you bait the traps. You use fermenting whole-wheat bread dough. Apparently they don't like white bread dough, but they like whole-wheat bread dough. And then there's actually lures that we can buy commercially that are aggregation pheromones for two nitidulid beetle species that we know can be vectors of oak wilt. And then every two weeks, Olivia would go up and check the traps and bring back the beetles, look at them in the lab under a microscope, identify them, and so forth. Degree days, we should all catch up on degree days. This is a measurement that we use in association with calendar dates. And if you're a farmer or a grower, or any kind of producer, you're gonna be real familiar with degree days. Basically, insects are cold-blooded, and if it's colder than 50 degrees, most insects don't do much at all, they don't feed, they're not active, they're not flying. Couple of exceptions, hemlock woolly adelgid, for example. But by and large, we use a threshold of 50 degrees Fahrenheit as the base. Degree days tell you how warm it has been over time using 50 degrees as a base, okay? If you wanna know this really well, it's online, you go to MSU Enviroweather site. It'll give you a much better explanation than I can do today. But what you're looking at is the accumulation of degree day. So if we have a warm, early spring, we can accumulate a lot of degree days by the end of May. If we have a cold, wet, damp spring, we won't accumulate nearly as many degree days. That's when we have a late spring, okay? And we can use degree days along with calendar days to talk about when insect activity occurs. And that way, we can be consistent from one year to another year, or from one region of the state, or even from one state to another state, for example. So if you ever wanna get degree day data, the MSU Enviroweather site is amazing. I think they're up to 90-some weather stations throughout the state, and you can click on a station and it will give you the current and the projected degree days on a weekly basis. So after all that, here's what I wanted to show you. This is is two years of captures of these little tiny sap-feeding beetles. The green line is the accumulation of degree days in 2018. The golden line is the accumulation of the degree days in 2019. We had a cold, wet spring in 2019, and you can see, we never did really catch up with 2018. The blue line here, this is the number of beetles per trap that were captured in 2018. You can see that peaked from about early May to early June. Another little blip here late in July, and then it just kind of fades to nothing. The green line is the captures of nitidulid beetles in 2019. It peaked later because it was cold and wet that spring, and it dropped. And then there's another little blip kind of here late July, August, and then it peters out. So just to show you what those data looked like, this is the first year, almost 1,200 beetles, 21 different species of nitidulids were captured, captured them by early April. We were getting at least a couple peaks in May and June. You can see here the peak was from 8th of May to 6th of June. It caught almost 60% of the total captures during that four-week period. And we have degree days that go with each of these calendar dates. The second year, it wasn't too different, everything was a little bit later. You can see here, first captures, again, were in April, last captures at the end of October. And the peak this year, it was about six weeks, I think mostly because a lot of May and even into early June was very cool and rainy, and these beetles are just not gonna be very active. And then we looked at contamination rates. So every time Olivia brought beetles back from a trap, we would take up to 10 beetles per species, per trap, per date, give them to Karan, and he would do some things to them so that he could culture them and see if they were carrying oak wilt spores. And here's what we found in 2018. There were four species of sap-feeding beetles, nitidulid beetles that were caught a lot, okay? Those four species and one other species, this one over here, Carpophilus dimidiatus, I'm gonna say, the brown Carpophilus beetle is what we called it. We only caught two of them, but one of them was contaminated. And all the contaminated beetles from these five species were captured in this May to early June period, okay? And not very many of the beetles were carrying spores, only 8% of the 225 beetles that Karan processed in the lab. Now the next year, keep in mind, these trees are being inoculated with the fungus in these same sites. So in 2019, we actually have a lot of infected trees producing a lot of pressure pads and mycelial mats. In 2019, six species of beetles, at least one of the beetles was contaminated and carrying viable oak wilt spores. Almost all of those were captured between the third week of May and the third week of June. Again, that was a little bit cooler spring. 31% of the beetles that were tested were contaminated. And then there was another little blip in August, just a few beetles, and a couple of those turned out to have viable spores on them as well. So again, this is kind of a summary. The first year, not very many beetles were contaminated with fungal spores because we didn't find any pressure pads that year, not in any of those three sites. The next year, after all the inoculations, several trees were infected, lots more pressure pads, 31% of what we screened were infected. And then another little blip, 3 of 24 beetles that were captured in August also had viable spores on it. So we know that most of the beetle activity occurs early in the summer, May, June, maybe early July. The contaminated beetles are mostly gonna be out and about when the pressure pads are present. And again, that's gonna be mostly May, June, maybe into early July. We also looked at xylem tissue in red oaks, okay? Xylem is sapwood, those are the cells that carry water. And those are the cells that are affected by the fungus. And when the oak wilt fungus gets growing in the tree, it blocks these cells and that's why the trees wilt and die. And if you know what tree rings are, I'm sure all of you know this, they're comprised of latewood and earlywood. So early in the summer, say, April, May, maybe June, there are large vessels in the tree, like you see here, this is earlywood. And then somewhere around mid-summer, the trees switch and they start producing latewood. And these are very thick-walled cells. You don't have these big vessels in there. And together that makes up one annual ring. And there is a thought that the earlywood cells, these big vessels, like you see here, may be more vulnerable to infection by the oak wilt fungus, just because they don't have these dense, thick-cell walls. Don't know that for sure, but it was something we kind of wanted to look at. And so Olivia would collect these increment cores from a couple trees, both sides of the tree every two weeks, bring them back, look at them under a scope, look to see if they were producing earlywood, and when the earlywood switched over to latewood. And again, our thinking was that earlywood may be more vulnerable than the latewood, okay? And then once latewood starts showing up, that's all the tree will produce for the rest of the summer or so you know that the earlywood production is done. And this is what we found. Earlywood was being produced on the trees again in 2018, from early May through mid-June. 2019, things started a little bit later and ran into the middle of June, again, because of those wet, rainy conditions. So if this is a thing, if earlywood is in fact more susceptible, it's gonna be during these periods when the earlywood is out there. So the bottom line is that the high-risk period when you have a lot of beetles active, you have a lot of pressure pads with viable spores on them, and you have a high risk of trees becoming infected because of the beetles, because of the spores, and possibly because of the earlywood presence, it's gonna be consistent with what the DNR has been saying for the last few years, Mid-April to mid-July. And this is a period, and just showing it's consistent with our results here. This is when we had vulnerable trees and active beetles and active spores. And this is the time of year when you don't want to be wounding trees. Things like pruning perhaps, more likely utility line clearing, maybe some harvesting or thinning operations, something like that. If you want to have zero risk, do your pruning in the winter. Otherwise, if you're on either side of that April 15th to July 15th timeline, there's a little bit of risk. It's low risk, it's not high risk. Be careful during that high-risk period. In terms of symptoms of oak wilt, this is what you typically... We talk about the browning or the water-soaked appearance of the leaves. The leaves will wilt, they will typically drop off, you can see, by the hundreds or thousands of leaves will drop off, usually in midsummer. If you look at the vascular tissue, this outer ring of xylem here, you can sometimes see this dark streaking or dark color there, but that's not enough. You can't really for sure confirm oak wilt is present based on those symptoms. If you look at the trees, most of the trees that die from oak wilt are dying in late June or early July, maybe further into the summer. You know, they can die pretty quickly. This is one the DNR uses as a worst case scenario. The utility company went through and cleared the line in May. And you can see this tree and some other trees along this utility corridor were dead by late June from oak wilt. Again, the appearance and the timing is still not enough to confirm that that is actually oak wilt. And in fact, the DNR forest health guys have tried to kind of track it, and they believe that 75% of the calls they get about oak wilt is actually not oak wilt. It's something else, it's two-line chestnut borer or armillaria, or maybe oak decline. If you have to confirm, if you suspect oak wilt is on your property and you need to confirm it, you're gonna have to collect samples. And there's some really specific ways that you need to collect the samples. You wanna get pieces of branches that are actively wilting, not dead yet, but definitely actively wilting. You can send them to the MSU Plant and Pest Diagnostics Lab. They do a lot of oak wilt screening during the summer. This is online, you can get this phone number. You can see the email address and the website, and so forth. To confirm oak wilt, they will use molecular techniques. They will extract... That's supposed to be DNA, not DNR, but they will extract the DNA and amplify it. And that is what will confirm oak wilt actually. So if that happens and you have oak wilt on your property, you know, what I would advise, what the DNR is advising is to get the tree down as soon as you can, really, but at least by the winter time and do something with the wood, ideally just burn the wood. There's some options for tarping it, but tarping it never works. There's holes in the tarp. You have to bury the tarp like with four inches of soil. Just burn it, burn that wood, have a big fire, take it inside, do something. That way, you're not letting that tree produce pressure pads and mycelial mats that will attract nitidulid beetles, and potentially result in other trees becoming infected by those vectors. They also want you to pull the stump if you can, to pull as much of it as you can. Now, we don't all have a nifty, little skid-steer or something to yank a stump out of the ground. But people that farm and people that work in the woods, there's ways to get a lot of the stump material out, because remember, that fungus is going into the stump and can spread via root grass. This is something that is being tested experimentally. The idea is that you do a double girdle around the tree. Right now, they're doing it down near the base of the tree, and then you apply Garlon herbicide, Garlon mixed with something called Premier Blue basal oil. And 25% of the formulation is triclopyr, that's the Garlon, 75% of it is the basal oil. And the idea is to try to kill the roots before the fungus moves down and is able to spread to another tree via root grafts. I mentioned this because there's a lot of talk about it. It's something that's being tried. It's hard to say, sometimes this seems to work, other times, it doesn't work. The rates that you need to use are not really defined yet. We don't know why it doesn't work in some cases, and it does work in other cases, but that's where the research is, in Michigan, in Wisconsin, and so forth. If you have a high-value tree, you can treat it with a fungicide, it's the active ingredient, it's propiconazole. You have to do a macro infusion. So you inject the fungicide with a whole lot of water and try to get it through the tree. The tree has to be pretty healthy at this point. Otherwise, it's not going to carry the fungicide up the tree where it's gonna do the most good. Usually, it's something that's applied in spring. In my experience, it's typically applied as a prophylactic. In other words, to protect healthy trees from becoming infected. It works sometimes, sometimes it fails. And again, it's not entirely clear why it fails sometimes, but it's not cheap. It's about $10 a diameter inch. If you measure the tree at breast height, so, a 10-inch tree, you're probably looking at maybe a hundred bucks to treat that tree, and you're gonna have to do it every other year if you wanna keep those trees protected. If you have an oak wilt center, infected trees, and you know things are spreading by root grafts, things get really complicated. And this is where you need to call in a consulting forester and somebody that has experience working with oak wilt. What they will do on forest land, this is being done quite a bit on state forest land to try to contain oak wilt and eradicate some of these centers, if these are your infected trees, you make a trench line, and it has to be at least five feet deep, and preferably six feet deep. And this is the secondary trench line. There is another trench line out here. You have to assume that oak trees near the infected trees have become infected via root grafts. Depending on the size of the trees and how many you have in this oak wilt center, that's gonna determine how far out you have to go with your trenching tool. Here, this is a vibratory plow. It's like a Ditch Witch on steroids. It cuts up and down, and cuts these things. You end up sacrificing all of these trees within these trench lines. And some of them might be infected, but a lot of them are gonna be healthy. It's expensive. It's hard to do. A lot of times you've even... The DNR will take a bulldozer in to clear out a path for the vibratory plow. This is a rock, you can see that that's not gonna work very well. They're trying to use the plow and create a line around here. And of course, if you have anything like buried utility lines, sewer lines, all that kinda stuff, you can't do it. It's just not very practical at all in those situations. So ideally what you wanna do is prevent oak wilt from becoming established in your wood lot or trees on your property. Don't do anything to wound those trees during the high-risk period. And we know that storms happen, okay? We get heavy winds, bad hail, the occasional tornado. If you have something that breaks branches off, you want to paint the wounds as soon as you can get to them. It doesn't matter what you use, latex paint, tree wound paint, any of that. There used to be a lot of guidelines about don't use tree wound paint. Those are done. Anything that creates a barrier between the wound and those beetles is going to help protect the tree. So with that, I am finished. If we have any questions, I would be glad to answer them. - [Lyndon] Deb, I don't see any in the questions and answers. And more of a general question, if we're looking at wood lots across Southwest Michigan, is oak wilt... We've heard everything from it's the disaster that's gonna take what oak out of our wood lots to wait and see. Where are you at on it? - I'm more in the wait-and-see-guideline team, I guess. If you think about all the things that have to happen for a tree to become infected with oak wilt, you know, you have to have a tree that has become infected and is producing pressure pads, you have to have the beetles visit that tree, you have to have a healthy tree that has a wound that's deep enough to expose the xylem, and the beetles have to find that tree and vector the fungus. So, you know, there is a lot of oak wilt, it's kind of patchy. Again, I think a lot of people see a declining oak or an oak tree that is, for some reason, not very healthy and maybe has two-lined chestnut borer or root rot, or a combination of all of those, and there's an assumption that it's oak wilt. And so that's why I just really wanna emphasize the need to get that confirmed in a lab. And there are some people that are making a living off of diagnosing and maybe managing oak wilt. And some of those folks are really good. I know there's a couple that have misdiagnosed it and you just have to be really careful, I think, with that. So, I'm in the wait and see. It's not great. You know, between ash borer and hemlock adelgid, and beech bark disease and oak wilt, forests are kind of having a rough time in Michigan right now. But I think it's something that while we don't want it and it's not good, I'm not sure that it's gonna wipe out oaks. I think we're gonna deal with it. - [Lyndon] Okay. So I'm assuming that if we have questions in the future, that you'll take the forestry entomology questions, and if people contact you. - Sure, I'm online, you can find my email address pretty easily if you go into MSU. So, yeah, I do a lot of that. - [Lyndon] Okay, and who does the forest pathology questions? Where would they send those to? - So I think that Monique Sakalidis will be back from maternity leave by probably the end of this month or early next month. And so she would be a good person to send for those pathology questions too. There are also forestry assistance program foresters pretty much in every county. They can be helpful. There are consulting foresters that you can hire, especially if you have a wood lot that you're trying to manage for, say, some type of a timber harvest or really specifically for a wildlife habitat. They can help you with that and they can help diagnose some of these problems. And I think some of the folks at CISMAs have some background in this and might be useful. Otherwise you can contact me, you can contact some of the other Extension forestry people. Julie Crick is up in Roscommon, and she does a lot of forest pest kinds of work. And, of course, the DNR, you can contact them. But James covers all of lower Michigan, and a guy named Simeon Wright covers all of upper Michigan. So they are stretched pretty thin. - [Lyndon] Okay, good. There is a couple questions that came in here just in the last second. - Sure. - [Lyndon] Lilly, for buying yard landscape trees, is there a label or certificate that shows me the stock has been inspected? - That's a really good question. So I'm not sure that you're gonna see that, especially if you go to what they call the big-box stores, you know? Something like a Home Depot or a Lowe's, and you buy your plants there. They should be inspected before they leave the state of origin, and most likely will be inspected when they arrive in Michigan having said that, you know, it doesn't always work. And if you're dealing with a shipload with dozens, or in some cases, a few hundred plants, that may not really be very practical. If you have the option of buying your plants, especially young trees, you know, I honestly don't care if... Some people like boxwood, I don't care about boxwood, but if you're gonna plant a tree, if there's any way to get the tree that was produced locally, at least in the state of Michigan, that's a great idea, that just limits the potential to have some other kind of invasive, nasty insect or pathogen come in with it. I don't believe there's gonna be tags or anything like that where you could really determine for sure that a tree's been inspected. - [Lyndon] And the last question here is more of a general one, the best way to start replanting a woods. And maybe you answered that with some of the people that are available to help, if you could... - Yeah, I think it's great. If somebody wants to start replanting a wooded area or maybe a field is out of production, and you're looking at turning that into kind of a wooded area, that's where I would contact a consulting forester because these tend to be people with a lot of experience. It's gonna depend on the soil that you have available. It's gonna depend on, of course, the weather and climate in your part of the state. They can make suggestions. If you're really interested in wildlife habitat, for example, there are certain species you might wanna include. If you're more interested in maybe leaving a legacy for us, something that that kids or grandkids can harvest in the future, that might be a different species. And so depending on your objectives and what you have in mind, that's where a consulting forester, I think, can be really useful. And if you go online, there is a directory of consulting foresters, gives you their contact information and where they're located, and where they will come out and look at your property. - [Lyndon] Great, thank you, Deb. We hope to see you in the future and appreciate your time spent with us talking about forest management. - [Lyndon] Okay, well, good luck. And everybody go out and enjoy your wood lots this summer. - Right.

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