An interview with Hailey Shanovich about her work understanding insect pests of hazelnuts in the Upper Midwest.
Hailey is a Natural Resource Science PhD Student and Research Assistant in the Department of Entomology at the University of Minnesota.
Link to Hailey’s presentation at the 2022 Upper Midwest Hazelnut Growers Conference: www.midwesthazelnuts.org/uploads/3/8/…you_nuts.pdf
JASON FISCHBACH 0:00
This is a podcast about new crops, you’re gonna love it. Join us on the cutting edge, a podcast in search of new crops for Wisconsin. When you’re developing a new crop that means at some point you have to deal with a whole set of new insect pests. Very true with hazelnuts and today we have an opportunity to talk with Hailey Shanovich, who is a researcher trying to figure out just what the insect pests are with hazelnuts. Hope you enjoyed the episode.
Today’s guest is Hailey Shanovich with the University of Minnesota. Hailey, welcome. Thanks for joining our podcast. Can you introduce yourself and what you what you’ve been working on there at the university?
Hailey Shanovich 1:00
Yeah, absolutely. Thank you for the introduction. I am a PhD student at the University of Minnesota. And so for my dissertation research, I study some of these different insect pests in hybrid hazelnut, and I’m in the Natural Resource Science and Management Program and hoping to graduate next summer. So yeah, I’ve been working in the system for three years now.
JASON FISCHBACH 1:24
So hey, we just got back from a driving tour across Wisconsin. And it’s, you know, pushing the last half of July. And there are Japanese beetles everywhere. And my understanding is you’ve been getting lots of questions or comments about it. So let’s just jump in right there. Japanese beetles, what are they? How do they affect the plants? Tell us everything you got?
Hailey Shanovich 1:43
Yeah, absolutely. So these beetles feed on so many different plants, as I’m sure all of you know, in hazelnuts, they do not feed directly on the hazelnut flowers, or really clusters even themselves, because the beetles are showing up in plantings in July, usually. So they’re mainly just feeding on leaves. There’s some studies already that show that they seem to prefer younger, more like juicy or leaf ear tissue. And so I’ve been noticing in the fields that they’re really going for younger plants, or plants that had been recently coppiced, and are having a lot of new growth and way less than more mature plants. So with the coppiced thing, I don’t we don’t know for example, with a plant that’s a perennial like hazelnuts, if the defoliation really is impacting the yield, or the plants, vitality that much certainly in young plants. So if they’re defoliating, really heavily newly planted hazelnuts, that’s definitely a concern, because those plants need to get established and start putting nutrient reserves down into the ground. And so they’re completely defoliating newly planted seedlings, that is a problem. But I we don’t really know if they’re feeding on like a plant that is well established that had been recently coppiced, if that’s really affecting the plant that much. And I really do not see a lot of feeding on taller or older plants. So yeah,
JASON FISCHBACH 3:23
Yeah, that’s interesting, because it’s just sort of this debate that continues to rage among growers, and even within our research group is how much damage is too much? Because it just It looks terrible, especially some of these younger plants. It seems to make sense that you’re reducing photosynthesis, so you should take some action. But on the other hand, if it’s, you know, not causing any real damage. So I don’t know is there? How would how would you figure out like, what the threshold is, what would have to happen? What kind of work would have to be done to be able to say definitively when it’s time to spray and when it’s not?
Hailey Shanovich 3:57
Yeah, absolutely. There actually has been some work from another student at the University in grapes and grape vines. And they were trying to understand if Japanese beetles actually reduced yield at high enough numbers in the grape crop. And so I think so far, that’s been the most research that’s similar to what we’re talking about in a perennial crop. And basically, what they found is that it didn’t really reduce the grape vine productivity at all. However, if it’s a really young plant, like I said, then it did seem to impact its vigor over the years and its ability to like put nutrients down in the ground. So what would need to happen is having like different densities of Japanese beetles feeding on young plants or whatever age of plants you’re interested in looking at and then quantifying either the yield or just the plant’s growth over time and for perennial crops, you do have to look at it for multiple years because these plants have reserves underground and can actually grow just fine. Usually, even though a lot of plants even if they get defoliated pretty heavily one year, they may have perfectly fine reserves to underground and not be very affected the subsequent year. But if you’re getting really high, defoliation, year after year after year, then it’s something that can definitely deplete the plants stored resources.
JASON FISCHBACH 5:32
So another question is the is there anything growers can do short of spraying to try to reduce Japanese beetle populations? I mean, if you spray them, and you kill whatever’s on there now, don’t they just fly in from somewhere else? Is there really anything we can do?
Hailey Shanovich 5:50
It’s a great question. So it’s really hard to control for them because they can fly from such great distances. And honestly, I will preface with, they can form really large feeding aggregations on plants. And it can look really alarming. Like it can look like there are just 1000s of beetles feeding. And the defoliation can look like a lot, especially on small plants. But we actually, as humans really easily overestimate the amount of defoliation that’s happening. So it’s easy to see a plant starting to look like it’s outermost leaves and top leaves are starting to get a lot of feeding. And so they kind of look late. See you’re skeletonized. But there’s still a lot of other leaf tissues, sometimes on lower leaves, or especially towards the bottom of the plant in the middle of the plant that might not be getting defoliated at all. And that’s still all perfectly fine photosynthetic tissue. So sometimes it’s just those like topper outer leaves that are getting defoliated. And that’s really fine. So sometimes we can see them feeding and it looks like a lot and really alarming but we don’t actually really need to take any action. And so that’s something that’s still being refined a lot that we need to refine as researchers is how to come up with some proxies that’s like easier for people to understand and kind of estimate when is that threshold where they need to take action, but things that you can actually do to control Japanese beetles is a highly debated because they can fly in from so far. And once they start feeding somewhere and start emitting, they have these scents that they admit called aggregation pheromones and so it attracts a bunch of beetles to the area. And then once they start feeding on the plant, the plant is releasing kind of some like defensive compounds and just like certain smells that beetles can tell it’s already have has been fed on. And so the smell of the fed on plants in the sense being emitted from the beetles is like constantly attracting more to the area. So it’s just really hard to control for them because I’ve heard many stories where someone will will spray something for the beetles and then like have to spray multiple times within the same week. Because there are so many flying in. I don’t really think that it’s necessary to be spraying unless you are really worried about your plants unless they are really young plants that are you’re seeing a lot of really heavy defoliation on something else that people do is very debatable is trying to mass trap beetles. So putting out those pheromone traps that are available for the beetles away from the field, not in your field or next to it. But kind of adjacent to it and try to just like constantly be a name will go for that trap you will get hundreds and hundreds in a trap sometimes even like 1000 a day and then just keep taking out the bag that’s attached and throwing it away or burning it or something. And so mass chopping is something people do something people are trying is planting like another really desirable planter crop that’s a beetles like adjacent to the field to try to lure them away. And there are many, many crops that are plants people use for this because the beetle has such a wide variety of things that feeds on and then another one is spraying some of these biological control agents people might have heard of. So they’re like ones that you can spray on the grass because as larvae, the beetles are living under turf grass and feeding on the roots and they really like that short turf grass. So if you’re mowing your field, if you have grass in between your hazelnuts, that’s definitely somewhere they could be laying eggs and then developing as larvae underground. And so there are I think one is the fungus that will attack the beetle that you can buy and put into a spray and spray that on the ground. And then another one contains nematodes that actually feed on the beetle larvae. Both are, you know, compared to just a conventional spray, definitely a lot more spendy because it’s like the living bio control agent. But with them, what happens is over time, they, either the fungus or the nematodes are multiplying underground. And so you get a lot more longer term control. But again, that only controls the land where you’ve sprayed, and the beetles can fly in for elsewhere. So that’s why these are all kind of controversial or debatable that how much control they really offer.
JASON FISCHBACH 10:46
So it does seem like maybe this is a pest where we kind of just write it out. In other words, there really isn’t that much we can do about it. If on mature plants, it’s probably not causing much damage. Of all the other things on our to do list. Maybe controlling Japanese beetles isn’t one of them. And we just let the system readjust like these, hopefully tend to do with invasive insect pests is the natural predators developer, or start to build and we see something start to stabilize. But the the pheromone aggregation to me was is kind of fasting that you brought that up, because when we walk through a planting, often we’ll see a plant that’s complete, not completely defoliate finishes littered with bugs in all kinds of skeletonized leaves, and then there’s a plant right next to it, like two bugs on it no damage. And we often think, well, boy that must be resistant. But is that maybe just a function of the plant next to it was the first one to get fed on and so that’s where they all go? Or is there actual resistance in these hybrid hazelnuts, some of them to Japanese beetle feeding?
Hailey Shanovich 11:51
That’s a great question. Yeah. Honestly, that’s one of the questions I’m looking at with my research. So I have been the last three summers taking data on kind of the distribution of beetles within a field. And so what I’m going to do is kind of do a spatial analysis to see if the beetles are just kind of grouped in a hotspot in the field, or if they are randomly distributed. And it’s more attributed to like what variety the hazelnut is, or what genotype so that’s something that I’m looking at. But actually, for some of my master’s work, some of my previous research, I looked at Japanese beetles in apple orchard systems, and we actually saw that they did prefer certain apple varieties over others. So there definitely could be some resistance within the hybrid hazelnuts, but we don’t, we can’t tell that for sure. Until we rule out that it’s not just their aggregation pheromones. And certainly when you do see a phenomenon like that, like a bunch of beetles on one plant and another one right next to it. It certainly can be due to the aggregation for everyone. So it’s yeah, a complicated question that I hope I can answer within the next year.
JASON FISCHBACH 13:07
So last question on Japanese beetles. We have a bunch of hazelnut plantings up in northern Wisconsin Spooner, Ashland, Bayfield. We don’t have any Japanese beetles never have. Is that because they haven’t gotten here yet? Is it because something about our soils or winters, it just lack? You know, we don’t have a lot of turf grass or golf courses or anything around? So what’s going on? Why don’t we have it and with climate change, are we eventually gonna have them?
Hailey Shanovich 13:31
That’s that’s also a great question. So I think in both Minnesota and Wisconsin, Japanese beetles are not in every county yet. From what I’ve heard from growers in the Driftless. region, for example, they just recently really have become established there in the last couple years, and previously, they had really never saw them there. So I’m assuming northern Wisconsin like up in Bayfield, Ashland area is probably similar. I mean, not similar landscape, but similar in that they might be just more slowly getting there. But the other thing is that they do really need turf grass to thrive in an area so if you don’t have a lot of golf courses, or athletic fields are huge tracts of turf grass near you, they just might establish way slower in the area. Certainly being up north to the there is some research being done not by myself, but other researchers at the University of Minnesota looking at how cold of underground temperatures they can survive. And I don’t think they’ve reached a conclusion yet, but that certainly could be a factor too, is just colder underground temperatures in the winter. Well,
JASON FISCHBACH 14:42
Well let’s move on to some other some other insect pests. So you you started your research project and one of the as I understand it, one of the questions was just what are the main insect pests of hazelnuts, I mean, this is such a new crop and no one’s you know, we kind of have some anecdotal evidence of it. causing some problems. But no one’s ever looked at it formally with the research mind. Right? So what are the main insect pests? You want to just give a quick interview of of each that you’ve found so far?
Hailey Shanovich 15:10
Yeah, absolutely. When I started the project, or came on as a PhD student on this project. Jason, you were one of the folks who I was talking to about what you’ve been seeing, because no one has really characterized what all the pests are, and kind of when they occur in the crop and things like that. So over the last few years, I found out that there are a handful of them. And so one of the main ones that you all already knew about, but weren’t sure what the species was, because most of these insects, a few of them are native, and a few of them are invasive. So some of the native ones just had never really been studied before, because they because we never grew commercial hazelnuts in the area, because we never had an economic crop that we were concerned about. And so these insects previously just fed on wild hazelnuts in the forest, for example. So we didn’t really know what species they were exactly. Anyway. So the hazelnut weevil turned out to be one of them, which is it’s common name. It’s official common name, it feeds on the hazelnuts of American hazelnut in the forest. And they have started to find folks hybrid hazelnut plantings and can infest those just the same as the wild ones. So they are the those small brown beetles that have a long snout if you’ve seen him before. And they will drill a hole into the hazelnuts, lay an egg in it, and then their larvae develop in the hazelnut eating the kernels so they directly impact the yield. And there’s nothing left after the larvae has developed.
JASON FISCHBACH 16:52
And Hailey, I should jump in let the listeners know that you’ve got a great presentation you gave at the conference back in March. And we’ve posted that on our website, Midwest hazelnuts.org. So folks want to see pictures of these these bugs. That’s the place to go.
Hailey Shanovich 17:07
Yeah, thank you for that. Yeah, there’s a lot of great pictures in there if you need a reference photo or just want to see them. But so that is one that we didn’t know exactly what the species is and figured out because there are actually multiple weevils that feed on all sorts of different native nuts like acorns and chestnuts and things like that. So we weren’t sure what the species was until recently. Well, so another insects that is of concern is this native food Preston. So it’s a type of beetle that bores into the wood of trees and woody plants, it’s related to its closest most famous relative is the emerald ash borer. So it does similar damage, or it bores into the woods of trees or woody plants. And it feeds on that cambium layer or the layer that the tree transports water and nutrients in. And so it essentially slowly kills the plant because it’s cutting off its nutrient transport. So we started seeing some damage in our plantings in Minnesota, where we were having some major branch die back, and we at first thought it was Eastern Filbert blight, die back. But then we started noticing some swellings on the branches and some exit holes that the beetles leave when they exit the branch. And so we realized that we had some type of food crested beetle, and just recently, I think this last summer, we figured out what species it is. And it did not have a common name previously, but we just officially got it named. So it’s a funny phenomenon with insects. The major authority of insect names is the etymological Society of America. And they have a huge database of all the insects that have official common names, and this was not one of them. So we got it officially named and we can refer to it as the Hazel stem borer.
JASON FISCHBACH 19:02
Now, you got you got to name it.
Hailey Shanovich 19:04
I got to name it. Yeah, so I just we just thought that was the most logical, straightforward.
JASON FISCHBACH 19:14
Yeah. Hazel stem borer?
Hailey Shanovich 19:18
Yes. So yeah, that is one of the insects we’ve been noticing. And we have it in plantings in Minnesota. But yeah, I have not heard a lot about it from other growers. And so that’s something also I’d like to mention is that in in Jason’s last newsletter, the last upper midwest hazelnut newsletter, there’s a survey for what insects you’re experiencing in your plantings, and I would love to know if you’re experiencing this stem bore. So
JASON FISCHBACH 19:50
I’ve got questions on both of these, but let’s keep going. So we’ve got weevils, and we’ve got the hazel stem borer what other pests
Hailey Shanovich 19:57
and then the other two major ones I would say are the Japanese beetles, which we talked about that people see. And also, actually not an insect but a mite, and it’s called the big bud mite. And that one is this microscopic little mite that basically infests both both the vegetative and floral buds of the hazelnut plant. So it can go both inside leaf buds and inside those floral buds, and it kind of has a really weird lifecycle where it infest the buds in summer. So it infests like the buds for the next year, in summer when they’re developing. And then it spends all of late summer and fall and winter, feeding on that internal blood tissue, and reproducing. And then by the following spring, like usually in May, they start emerging from those buds and going to find the new developing buds. So they spend most of their lifetime, safe inside vegetative or floral buds. And what happens is, they’re called Big bud mite, because the feeding that happens inside the bud causes it to basically swell up are turned into a gall. And so the buds look enlarged, and they look about like three or four times as big as normal sized on infested bugs on the plant. And so that’s where it gets its name, but essentially, any infested buds will usually not develop. So they either won’t develop into leaf tissue, or they’ll develop really deformed. And so people might have seen this on their plant, if they ever see leaf tissue that emerges and just looks really wonky or funky you’re looking at probably was because it was infested by these mites previously, and they were eating on most of the leaf tissue in there before the bud tried to open up. And then with floral buds, their feeding just causes the flower to abort. And so basically, you just don’t get hazelnuts if they were feeding on floral beds. So they can also directly impact yield. But they they do unlike some of these other insects seem to really prefer certain hazelnut varieties over others, I see them a lot on some very specific varieties and not on other ones. And we’re still trying to figure out why that is exactly, but we think it has to do with the timing of when the buzzer opening up. So each of these Fridays has slightly different. We use the word phonology, which means kind of the timing the study of the timing of their lifecycle. And so each of these plants, even though they’re like all super closely related in all hybrid hazelnuts, they do have slightly different timing to their development. And so some of the varieties open up their buds a little sooner than other ones. Even if it’s just a matter of days, we think it might be contributing to this phenomenon. But we don’t really know how it’s an invasive species. So it came over long ago, when folks brought hazelnuts to brought European hazelnuts to North America. So it’s associated with European hazelnut and has originally came from Europe. But we definitely have it in our hybrid hazelnuts here in the Midwest, it must have got transported on nursery stock or something when folks first started breeding way back in the early 1900s. And basically, it seems to be a very variable pest like some folks have never seen it in their plantings in the Midwest and others have some of it I have rarely heard of really high infestations. Some of our experimental plantings in Minnesota have high infestations, and I know you have a fairly high one in Bayfield Jason.
JASON FISCHBACH 23:55
Yeah and we’ve really seen it go up and down from year to year, for whatever reason.
Hailey Shanovich 23:58
And that’s another thing, it does seem to vary a lot by year to year. So those are the four. I think that’s four. Right? Those are the four main pests that I’ve been looking at
JASON FISCHBACH 24:06
Of these four. I think I know your answer, but which is the biggest concern, which one?
Hailey Shanovich 24:15
Yeah, from everything I’m seeing and hearing from other growers or even hearing from growers, the insect I get probably the most questions about by far is the hazelnut weevil. Yeah.
JASON FISCHBACH 24:28
Right. And you’ve seen losses of 30, 40, 50%. How high Have you measured in terms of percent of nuts that that were predated?
Hailey Shanovich 24:37
In our fields in Minnesota, so in in this is around the Twin Cities area we have been seeing between like 20 and 30% losses every year. So yeah,
JASON FISCHBACH 24:50
And it’s always the the hazelnut weevil there. Are there other weevils like that are infesting oak trees if you plant hazelnuts next to oak trees that the move from the oaks to the hazelnuts or is that the only one of concern?
Hailey Shanovich 25:04
That’s a good question. So that’s something we weren’t sure about when I first started, whether this is just one species, or is it multiple native weevil species? infesting the hazelnuts, and from what we’ve, from what I’ve seen over the last three years and what I’ve, yeah, what I’ve seen is that basically, it’s just one species. It’s the species the hazelnut we bought, and it exclusively feeds on hazelnuts. So it cannot complete its lifecycle. It cannot even survive on other plants. So it can’t survive on oak or anything like that. So it is specifically just from has come like from wild hazelnuts. There are weevil species that feed on oaks, but from what I can tell, none of the ones we’re seeing in the hazelnut are ones that feed on oak trees. So you don’t need to worry about if you have like oaks in your windbreaker tree line or something that you would be attracting? Yeah. So it’s really just from wild hazelnuts.
JASON FISCHBACH 26:05
All right. Well, let’s dig in on on weevils given us the most important one. So describe its lifecycle. What’s it feeding? When’s it feeding? When’s it mating? How’s it overwintering? If we wanted to try to monitor it, or scout for it, how do we do it?
Hailey Shanovich 26:20
That’s something that we also didn’t really know when I first started, like, people had mentioned seeing them at various times throughout the summer. And it’s such an understudied insect, just being a native forest insect that no one really knew much about its lifecycle. So over the last three years, I’ve kind of parsed it out. And so basically, the weevil adults emerge from the ground in starting in May. And so you can start to see weevils on your plants, depending where you are as early as like mid to late May, and depending on the temperatures that year. And then the weevils kind of hang out in the plants for a bit and feed a little bit on the leaves, it’s, it’s, it wouldn’t be very noticeable to like see any defoliation from them. But they kind of all are merging and waiting for each other to emerge and just hanging out on the plants. So you can usually see that starting to happen in May.
JASON FISCHBACH 27:14
And what’s the best way to to find them? I mean, we used to look for them, and we never could find them. But then you came along, and all of a sudden you found them everywhere. So what’s the what’s the secret?
Hailey Shanovich 27:25
Yeah, um, so a way you can sample for them is called beach sheet sampling. And so it’s a very low tech way to sample plants that entomologists use and basically you just take a canvas or a tarp or something and lay it down in between your hazelnut row. And then you use like a broom or whatever, some sort of large stick baseball bat to kind of gently like beat the plant onto this tarp or canvas. And they fall out of the trees super easily. They they’re pretty clumsy, they don’t really good at hanging on and actually their innate like reaction to things to predators and to something like being shaken out of the tree is to play dead. So they will just fall onto the canvas and play dead, maybe start to walk away after they recover. But so you can see them pretty easily that way. They’re probably as big as one of your fingernails. So they’re fairly easy to spot. And they kind of range from tan to more of a darker brown color. But they’re pretty identifiable because they have this long snout on them. And yeah, you can look back at my presentation photos to see some photos of them. But they that’s the easiest way sometimes to have you just are looking at the developing clusters, especially starting in June more. Sometimes you’ll just see them sitting on the cluster. And they’re color contrasts the involucre really well because the involucre is like a light green color. And they’re like a brown color. So sometimes you can just see them on the clusters.
JASON FISCHBACH 29:02
So back to the lifecycle. They’ve emerged from the ground, the adults are up in the canopy and May, usually in May, there aren’t really any clusters that you can see. So and you said they’re just hanging out waiting for everybody else to show up. So So now what?
Hailey Shanovich 29:17
Yeah, so they’re hanging out waiting for everyone else to show up and for clusters to start developing. Then moving into June. They will start meeting once the rest of the weevils have emerged. So usually like mid June they start meeting and then once those clusters start developing, they will start laying eggs. So usually that starts in like yeah, probably like, like, it’s it’s very quick. It’s basically as soon as there are clusters that you can see. So it’s usually like mid to late June is like peak egg laying and then that goes into the first week of July. So this year this spring has been super weird where we had just such a weird spring and everything’s really delayed this year. So this year I’m actually seeing a lot of weevils laying eggs. Even till now just this last week when I was out in the field. I saw quite a few weevils still laying eggs. So this year, they’ve been pushed back a bit, I think. So it could go. The peak time that they are mating and laying eggs is like mid June to mid July.
JASON FISCHBACH 30:28
So now the eggs are laid on the developing clusters and does the nut can’t be it doesn’t develop around the egg, the egg hatches in the larva tunnels in how’s it getting into the
Hailey Shanovich 30:42
Yeah, so the female she uses that really long snout, she has to basically drill a hole into the developing shell of the of the hazelnut. And so it’s the hazel nut shell hasn’t really hardened yet. So it’s fairly easy for her to do this. And then she lays the egg into that hole. And so the egg is basically almost drilled all the way into where the kernel will be developing. So then that egg will hatch inside basically, and be able to access the kernel. So sometimes the kernel hasn’t even developed yet. And the larvae is like waiting for the kernel to start developing. So it’s basically as soon as kernel development is happening, those eggs are are being laid. Yeah. And so then the larvae will feed on the developing kernel throughout the whole summer basically, and then right before harvest when the shells have hardened, and the hazelnut is maturing, is pretty mature, almost ready to pick. The weevils will usually drill a hole. Yeah, I think it’s normally towards that same place where the egg was first deposited. So there’s already kind of like a hole started there. And then they can chew their way out. And they dropped to the ground. And they actually burrow underground and overwinter till the next year. So they will like drop immediately under the plant. So if you are starting to have or have noticed a hazy hazelnut weevils in your planting, they are not moving in and out of the field, they are just dropping immediately to the ground and overwintering right there in the field,
JASON FISCHBACH 32:23
A pest of this magnitude or potentially 20 to 40% losses. I mean, this is not something you can just tolerate. If we’re going to try to grow hazelnuts commercially, we’re gonna have to control this one way or the other. So talked a little bit about controlling them as the larvae are emerging from the nuts in the fall, which is great, except we’ve lost all those nuts. So what do you think at this point? Are there other things we can do using IPM principles to to try to control this insect? What do you feel like are best options at this point?
Hailey Shanovich 32:55
Yeah, this insect is tricky to control because it spends the majority of its lifetime as the larvae inside the nuts. So it’s like safe inside the nut for most of its lifecycle. But the adults do show up before the criminals have really started to develop. So there is this window of time from like, mid May to early June, where the adults are not laying eggs yet. So I think that timing will be really crucial. If folks have really high infestations in their fields to do some type of spray,
JASON FISCHBACH 33:34
Are they’re going to be some of these softer greener chemistries is we can use or is this going to be like plum curculio?
Hailey Shanovich 33:40
That is a question that I have not had, like the ability to look into yet we that is a great question, but we really need to do some organic and conventional insecticide trials with this insect to see what works because weevils are a very hardy, yeah, I’ll use that word hardy beetle species when it comes to beetles. They are built like little. I don’t know what the word is. They’re basically wearing some pretty tight fitting armor. So weevils are I think one of the insects that they have realized can survive for a short period of time like in a vacuum or without oxygen for a while even because they are so tight fitted. Their shells are so tight, their exoskeletons are so tight that they basically can survive without oxygen for a while. So this is why it makes them hard to treat with insecticides because they can basically hold their breath for a long time. And so sometimes they can be kind of resistant to certain insecticides. However, not all weevils are like this, but that’s why they’ve had some trouble with plum curculio I know. So, insecticide trials definitely needs to be done also. Of all the boll weevil and cotton is another one that’s like something that’s been a nightmare to control over the years. I know. So, yeah, that’s not something I’ll have time to investigate during my time here, but I know in Europe, they have a very similar weevil species that does the same thing to their hazelnuts in Europe. And I think the only insecticide they have found to work are pyrethroids. So I definitely think this needs to be work that’s followed up and yeah, trialed.
JASON FISCHBACH 35:30
Do I have it right that even if you live next to a while, like if you’re planting was 10 feet from a wild hazelnut planting, where maybe the you know, the weevils have been there for a long time? It’s not like there’s an army marching into your, your hazelnut planting every year from that wild planting? Right? They stay pretty close to home. Is that true? And so maybe the main concern, is that just a slow build up over time within your own resident population. Is that Is that fair to say?
Hailey Shanovich 35:57
Yeah, I mean, I’m not 100% Sure, because I haven’t studied their movement from like forest to field but I, I, from what I can tell, they’re not moving around a lot. They are just kind of staying put staying where they are. Maybe they moved from like one plant to another within a field. But I don’t think they’re like, marching from the forest to the hazelnut plantings like you’re saying, Yeah, I think that’s safe to say, and they’re not very good fliers, either. I will add, they technically have wings, I really, really have rarely ever seen them fly. I think they’re just kind of clumsy fliers, and prefer not to do so. So I don’t think they’re flying around either to different plants.
JASON FISCHBACH 36:39
Well, maybe maybe this isn’t going to be that big of a deal. Because I mean, growers have an incentive, pretty strong incentive in the fall to harvest every nut they can. And so if we keep them out, you know, by harvesting, usually, it seems like I mean, my experience is you go out you harvest tasting lots. And then you come back the next week, and the desk, in your office say is covered and weevils like they’ve emerged after you harvest them. It seems like so I wonder if just picking all the hazelnuts is maybe the best strategy. So those weevils can’t drop down into the larva can’t drop down into the duff layer to perpetuate the lifecycle?
Hailey Shanovich 37:17
Yeah, yeah. So the larvae since the eggs are being laid over this whole period of like a month, kind of, like I said, from late, or sorry, from, when did I say mid June, to like mid July. There, the larvae are kind of all developing at slightly different rates, because they’ve all been laid over a month. And so some will have left when you’re harvesting. So if you see exit holes, ever on your nuts, like a little hole that just Yeah, a little hole. And basically, if you would crack the hazelnut open, there would be nothing inside or just like no kernel, essentially, or half eaten kernel, the larvae has already exited. But a lot of times, someone like you said Jason will harvest and you’ll have a lot of larvae emerging after you harvest. So that’s great. That’s kind of like you did some sanitation worker ready. So you’re obviously those weevil larvae will not be able to drop and get into your field. So sanitation like that, like not allowing a lot of nuts to drop is certainly a way to have control as well. But I will say like you said I don’t, it would be awesome if it doesn’t turn into a big problem for all the growers. But what I’ve heard is from folks is some people have never seen him. And so they might just never get on where they are because maybe they don’t have forests with wild hazelnuts there or who knows or just haven’t bought nurse just didn’t have any on their plants when they planted them. So some people just might not have them and others who I’ve heard from have had them for years. So I think it depends if you just have a built up population in your area or not too.
JASON FISCHBACH 38:58
Let’s switch bugs here for a second. The hazel stem borer to me is kind of a fascinating one because in the hazelnut world, we often see dead branches. We’ve seen dead branches since the project began, you know, 20 years ago. And we often attributed to maybe there’s little Eastern Filbert blight, or that the plant sort of recycles its wood because sometimes we see a branch that puts on a ton of nuts. One year, the next year, the branch looks pretty sick and is dead. But I wonder if maybe what we’ve been seeing is a lot of Hazel stem borer and we just have no idea. So in a sense of how widely distributed it is, if growers wanted to diagnose it potentially, you know, take us through exactly how they would do that or what they would be looking for, to see if it was stem borer.
Hailey Shanovich 39:44
Absolutely. Yeah, so I’m here in the Minnesota plantings. We were seeing a lot of stem die back and the first year I was out here 2020, summer of 2020. I had just been told that yes, but it was the same reasons that you said Jason, and then summer 2021, we had to take some cuttings of I wanted to do like a lab experiment. So I was taking some cuttings from the hazelnut plants to bring inside. And I started noticing that some of these cuttings had swellings and little holes on them. And so honestly, if I went to, I feel like a lot of times, or at least for me, I hadn’t looked so closely at the individual stems of the plant, because they get it’s a shrub and they get so bushy and leafy. And it’s hard to even see some of those individual stems, especially towards the center of the plant. And so I just hadn’t been looking there. But basically, it’s somewhat easily diagnoseable. Because what you’ll see is, it’ll be, I’ve noticed, they don’t tend to like branches that are too small and diameters, so I’ve only personally seen them on well established, more mature plants. So plants that are probably six years old or older that starting to have a wider diameter stem. And they tend to burrow not super close to the base of the plant, I’ve noticed it’s kind of more in the middle range. And it can be all the way up into where the stem is starting to like, branch out and have leaves. So it’s kind of in the mid range of the sun. And basically what happens is where the adults lay there, the adults will kind of lay their eggs into the bark. And then it’s actually the larvae that burrows around in the cambium. And they burrow in a circular fashion. So they kind of burrow around the circumference of the stem. And it directly cuts off nutrient transport because they’ve made a full circle line around the stem and is like completely cut off the nutrient transport for that stem. And it will cause a gall to form it’s not super noticeable, but it looks like a swelling. So it doesn’t look like a gall how we normally think of where it’s a raised like bump or like hemi spherical shape, but it’s more of this like swelling on the branch. And so if you are seeing that you can like cut off that branch. And if you want to confirm if there’s a larvae in there or not, you can actually like use a knife to kind of dissect that swelling area and see if there’s a grub in there. And they kind of look different than how we usually imagine of grub. So they don’t look like Japanese beetle grubs. They’re in a different family. And so they are more of the kind of almost look like a tapeworm, which is kind of nasty, but they’re kind of long gated white shape. And they also when they exit, they leave kind of this characteristic exit hole, it’s in the shape of like the letter D. So sometimes if a branch is already dead, and you’re curious if it might have been from one of these beetles, you can look and see if there’s a swelling or one of these D shaped exit holes. And if you see an exit hole that’s like absolute confirmation that there was one of these beetles in there at some point. So those are the most characteristic things and I think there’s photos of all of that in the presentation as well.
JASON FISCHBACH 43:15
Okay, and there’s the the stem usually like it leaves out in the spring and then dies. So it’s it’s really striking or is it a stem that just doesn’t leave out in the spring.
Hailey Shanovich 43:26
Um, it can have I’ve seen it. I’ve seen them have all sorts of symptoms. So sometimes the branch will be if it’s like that year like damage from that year, the branch might leaf out and then die over this summer so it can look wilty later in the summer, especially like in August. So I remember last August seeing that’s when I first just last summer noticed so many of these in our Minnesota plantings as we were starting to see a lot of wilting branches, and we did have a drought last summer. So I was wondering if it was the drought, but then I started to notice that all of these wilting branches had these D shaped exit holes on them. But also I will say that we pressed it’s our kind of known for targeting weakened trees and so drought ears make it much easier for the Beatles to so plants kind of have these defensive compounds they can use to deter insects and pests are somewhat sensitive to that. And so in a year where the plant is stressed, so in drought years and makes it way easier for the Beatles to develop it successfully inside of the plants. So I think last year we saw so much damage here in Minnesota because of the drought and I’m wondering if we’ll see some this year. I know Wisconsin has been getting a lot of good rain but the Twin Cities area has been really dry actually. So I’m wondering if I’m going to see a lot of that here again this summer.
JASON FISCHBACH 44:57
The stem borer beetles are these beetles that growers are likely to see. I mean, do you have to really look hard? Are they fly on night? Or what? are moving around at night? Or how do you? How’d you ever find these, the adults?
Hailey Shanovich 45:07
Yeah, the the adults are actually, sadly really pretty. So they just like Japanese beetles, like all these beautiful insects are just terrors. But so this insects, the adults, I noticed them flying around in June. So the adults were taking data this summer as well. But we think the adults kind of emerge in June and are mating and laying eggs during that time period. And I don’t know much this is a very understudied species, unlike Japanese beetles, but it kind of seems like they also aggregate in an area of the field and our meeting and kind of flying around. And they’re like a metallicky, reddish to purple color. And they’re pretty small, they’re probably only about the size of like a pinky nail finger or your pinky fingernail. And so they’re pretty small. But you’ll see I saw like a whole, almost like little swarm of them flying around a section of field here in St. Paul, this summer. So you can see the adults, if you’re like in the right place at the right time.
JASON FISCHBACH 46:20
Maybe the last main pest to your big bud mite, what’s your take on? Is there anything we can do about it? As a grower? You know, we’ve tried to monitor for it ourselves, and we failed miserably. And then you helped us but it took, you know, sending samples to you using a pretty decent microscope, because these things are small. And it’s hard to find when they’re when they’re moving from bug bugs. So just talk us through, you know how you scout for these? And if there’s ever anything we’re going to be able to do about them?
Hailey Shanovich 46:54
Yeah, absolutely. I will just say they are extremely hard to scout for because they are microscopic. And so I was kind of describing their lifecycle before. So they’re similar to the weevils pretty safe for most of their lifecycle in terms of us being able to do some sort of control. So they’re kind of safe inside of the plant buds for most of their lifecycle. But there’s this period of period of time, it’s like about what I’m finding is about 90 days, so from late April or early May, all the way through June, there is a period or sorry, late May, sorry, early May through Yeah, probably the end of June, early July, that they are migrating into new buds. And so that is the period of time where something like a spray could be done, and when monitoring should be done, or scouting. So basically the mites are leaving last year’s buds and migrating into new buds. And so when they migrate, they’re like moving along, the branches have the same plant, or sometimes they’re using the wind a little bit to disperse them to neighboring plants, but they’re not moving very far from my understanding. They’re either yeah dispersing with, like with in the same plant or on to just neighboring plants. And they are moving in huge. Like basically they all leave in one big flow from the previous budget that they were in and there’s like hundreds of them and each big but basically. And so what I was doing to monitor for them was using like a double sided sticky tape. And I taped that really tightly around a stem that I saw a big, big button. And so when they would walk across the tape to get to a new neighboring bud, they would get stuck on the tape. And then I could look at that tape under a microscope. But I will say took me a really long time to train my eye to see these things even on a tape under a nice microscope because they are very tiny. They’re only a fourth of a millimeter long. And they are kind of a translucent white color. And so if there’s anything else on the tape, like pollen blowing around from other trees or grasses or some sort of like sand or dust or something, it can be incredibly hard to see them. So it is just such a pain to scalp for these things. And so that has been part of my dissertation research is monitoring for them for the last three summers to kind of pinpoint when their peak migration is happening. And then create a degree day model so that growers can then just use this degree of a model to predict when they’re migrating instead of having to scout for them personally. And if you are if you do have a large infestation of them in your field and are worried about them, then you could do a spray during this peak migration period. And so far, that’s the only form of control I’ve heard about folks using in Europe. But there is a lot more promise for resistant varieties as well with this insect more so I think, than any of the other insects we’ve talked about today. And they have had some success. I know, in Oregon with the European hazelnuts breeding for big bud my resistance there. So yeah, there’s hope for this insect to be controlled.
JASON FISCHBACH 50:28
Yeah, we had one of our top selections, what we call SPC2D5, we threw it out. We’ve discontinued working with it just because the big bug mite damage was so bad. You know, we didn’t want growers to have to deal with that. So seems like breeding is going to be the best option here buying resistant varieties. Yeah. Well, Hailey. So one bad thing about PhD projects, is that they come to an end. From our perspective, I’m sure you’re eager to move on. But how much time do you have left? And in? What do you wrap it up on the project? And then what’s next for you? Do you know yet?
Hailey Shanovich 51:08
Yeah, thank you for asking. Yes, I, as much as I’ve enjoyed the research I’ve been doing and everything and all the people I’ve gotten to meet. Graduate school is really rigorous and tiring. So I am excited to graduate and move on. But I am excited like this work, getting to investigate so many different insects, and just getting to be the first person who looks at all of these, I have a lot of ideas. And so whoever comes next, whether it be more students or other researchers who get involved, I have a big list of ideas and other projects that should be done to follow up. So I’m excited to pass on some of some of that. But I have about a year left. So I haven’t exactly entered the job market yet, but we’ll be looking so yeah, if there anyone listening who has cool job opportunities for a PhD graduate, please let me know. I’m interested in research positions or some sort, I would love something that I could continue doing research. So yeah, hit me up if you have any leads.
JASON FISCHBACH 52:23
Well, Haley, on behalf of all the growers, everybody involved the industry, thank you, because we knew nothing. And you have moved this industry so far ahead. It’s been just great. So you’ll, you’ll publish the dissertation. Yeah. And that’ll be available online at some point. Yeah,
Hailey Shanovich 52:38
Yes, I will be. So my dissertation gets published with the university, and that will be available online, but it’s going to be like one really massive book and not be fun to read. So I’m also publishing each of these, each of these chapters on each of these different insects separately. So they will also be more digestible, shorter articles on each of these insects. And I hope to make kind of a rough picture guide to the different insect species. And what we know about them when we’re they’re occurring. Just kind of Yeah, a rough guide, it won’t have a lot of control recommendations, like I said, because that needs to be worked. That’s followed up by someone else. But I will try to have like a short and sweet guide that has all the different insects and when they’re occurring in the crop. So yeah, that would be great.
JASON FISCHBACH 53:33
So you’ve still got a year left, though so I’m sure we’ll hear from you again, maybe toward the end of your project. We’ll have you back on and also, I’m guessing you’ll present at our conference next March. Yeah.
Hailey Shanovich 53:43
JASON FISCHBACH 53:47
Good. Great. Well, Hailey, thanks so much for your time. This has been great. And again, if folks have questions or want to follow up, see pictures, Hailey’s presentation is on our website. So Hailey anything left to add?
Hailey Shanovich 54:03
to it via email. Perfect, thank you, Hailey.
JASON FISCHBACH 54:35
Brought to you by the University of Wisconsin Madison division of extension
Transcribed by https://otter.ai