I'm Ryan Miller, Crops Extension Educator earlier this morning. We recorded in an episode of the Strategic Farming Field Notes program. Strategic Farming Field Notes is a weekly program addressing current crop production topics. A live webinar is hosted at 08:00 A.M. on Wednesdays, throughout the cropping season. During the live webinar, participants can join in the discussion and get questions answered.
An audio recording of the live program is released following the webinar via podcast platforms. Thanks and remember to tune in weekly for discussion on current cropping and crop management topics. Good morning everyone, and welcome Today's session of strategic farming field notes. Today we're going to be covering quite a bit about what's going on in the insect world here.
We know we've had a few developments going on both Southern Minnesota dealing with a lot of army worms, but then also Northwestern Minnesota. We're looking at a new small grains and insect at least to the area up there. To start off, we'll talk to Dr. Ian MacRae. He's based out of Crookston, an Entomologist up there. And then also we have Bruce Potter, IPM specialist based out of Lambert,
Southwestern Minnesota. On two. I want to remind folks that these sessions are brought by University of Minnesota Extension with very generous support from Minnesota Farm families through the Minnesota Corn Research Council and the Minnesota Soybean Research Motion Council. Again, we're glad you could join us today for today's update here. My name is Anthony Hanson. I'm a regional extension educator in integrated pest management based out Morris.
I think with that I will hand it off to Dr. Ian MacRae in just a second here. I do want to say that one of the programs that we have an extension is what we call our Western IPM Scout Program. This is funded both by the Minnesota Wheat Growers and Minnesota Soybean Growers. And it was about two weeks ago that both our scouts started finding insect in northwestern Minnesota, specifically Norman Oman and a little bit in Red Lake County. And this was cereal leaf beetle.
And we found out partly through an, that it was the first find in northwestern Minnesota. You want to talk a little bit about what's the big deal with cereal leaf beetle here and why that was both an exciting find but also a worrisome find for the area. Sure. Thanks Anthony. Well, certain leaf beetle is, can potentially cause economic loss. And what it's in basically all the states that surround us, in my time up here, we had not seen it in small grains.
The MDA doesn't have a report of it being collected up here in small grains. I spoke to one of the local a couple of the local scouts they had don't recall seeing it. Bruce Potter who was up here actually, Bruce. You were up here before? I was. You were up here in the '90s? I guess older than you are. Yeah. But only by a few months. But Bruce seems to remember seeing it, so it might not necessarily be the first time that it's been hit.
And it wouldn't be unusual to have an insect come in and disappear if the environmental conditions weren't right and have a reinvasion when they were. What we do know about this particular insect is that it's boy, what a charmer to work with. The adults are quite distinctive. They're about a quarter of an inch long, but they have very, very dark metallic blue wing covers. The posterior portion of the insect is covered by this really bright, dark blue and it's very metallic.
And then they're thorax, so the legs are attached to their head are a very vibrant orange. They're not hard to miss. The adults really aren't hard to miss, but they're not around for a long time. They overwinter as adults, so the adults will emerge in the spring. They're usually very similar to a lot of other beetles. Overwinter leaf cover and duff in the hedgerows and shoulder belts move into a field, they make legs, they don't feed a lot.
In the spring, a little bit the eggs will hatch and you have these larvae. Now, these are just charming little creatures because they're a light yellow color and against the green of a cereal grain, they would really stand out, cover themselves with mucus in their own feces. And now they're this really dark brown black blob that actually it resembles a little bit like a slug, but it also looks like bird droppings when they're very small. And it's probably a method of avoiding predation.
Do you know of any other insects that we deal with? At least the field crop side of things that do that? Because, yeah, that's not something I should say. It's, Thank God there's other leaf beetles that do that. Thought Lily as well. I know a needles will do the same thing. They also seem to have many of them seem to have this bright yellow color as well.
Yeah. The adults and the immatures will feed in the same way, and that they start on the top of the leaf, they're usually on the top of the leaf. They start feeding down through the leaf material, and they stop when they get to the bottom of the bottom leaf cuticle, which leaves this empty area, and it looks like window painting. The adults feed in rows.
They're fairly mobile and so they're feeding as they're walking up the leaf and you have these basically windowpane look like tracks as they go up these very narrow, long tracks, the larvae which are not as mobile as the adults. They do have lakes, but they're not as mobile and they have a tendency to feed more in a patch across the leaf.
That actually turns out to be a lot more damaging simply because when they take right down to the cuticle, that cuticle is going to eventually dry and the rest of the leaf, even if it's fed upon or not, will drop off and you lose a lot of photosynthetic material there when the grain gets into. And I should specify, these are only on grassy crops, small grains, grassy weeds, things like that is where you'll find them when they they're feeding.
And moving around, you have a tendency to see them move over to the flag leaf when the flag start developing and then they're very evident. It's not hard to find them. Really, the thresholds are reasonably low, which makes because they can cause a lot of damage. When the plants are small, maybe a little six plants, the threshold is three eggs or three larva per plant. When they get a little bit older, boot, the flag starts coming up. It's one larva, a flag leaf.
And a lot of that has to do with how devastating they can be to a flag leaf. We know this thing. I've talked to Dr. Joo over in North Dakota, she's dealt with this an awful lot more than I have. I gave her a call and took a short serial leave, beat one on one course from her. She's been dealing with this for several years now and she seems to think that they're moving, or moving east rather out of Montana, and that seems to be how they're moving across North Dakota.
She said they find it most years in a number of different counties, but usually it's not at economic populations. And she said occasionally you'll get a very similar to what we're seeing here. Occasionally you'll get a field that has a heavy population, but most of the ones that we've run into here's you'll find the damage, but it's oftentimes hard to find a large, and there's a lot of natural mortality with this insect.
There's parasites and peristoids and predators, and so I think we may not be seeing a huge outrage. I can tell you where we are and are not finding it. We're finding populations in Noman and in Norman. We've recovered in both. The one field that we first found and it was one of the ones at the IPM found was actually heavily populated and at one point it probably was at a point where it was a threshold, but the vast majority of threshold of fields have not been.
In fact, that was the only one that I saw that was even close. And I'm remembering the numbers a little bit too. And I think one of the first fields we sent you to, at least the scout found about 25% of the plants were infested. And I think that's when you said that was a threshold in the past? It was a little bit too late Based on yeah, based on the feeding. I would say there used to be an awful lot more lava in there than what we saw. The distribution was very even across the field.
I mean, I was we were walking transect the field, you know, even strung out. We had about five people in the field and you could find damage all the way out into the field and you could find Larval. So, we had weather field too, Red County, that one had about 33% But that's a research trial plot? Actually, we didn't remember. So, yeah, we did we did scout down Highway Nine and were coming back from one of the other things we were doing out there.
And we did not find it on any of the wheat fields on nine, we did find it up to I think, about 15 to 20 mi away from that one. Very heavy one? Yeah. Yes. So if one, those are counties, at least for a lot of folks in Southern Minnesota, that's far Northwestern for them. Is this an insect that folks should be keeping an islet for across the rest of the state? I know Southeastern Minnesota roughly.
It actually had been documented back and Mda did a survey from 2010 historically been found down there. But from our conversation, it sounds like it hasn't really been economic threshold for people notice it too often down there. Yeah. And that's what I'm starting to think, given the distribution, this is not something that's probably just come into this area in one year. But I'm guessing at this point because we don't know what the full distribution is,
we don't know how long they've been there. But The populations are so low in some fields that it's entirely possible. This is just something that's been here for a while, we've just missed. There was one field we were in that we really had to look hard and we did find a little bit of damage and we found one larvae and that was after being in that field, forths possible they could be there at very low populations, and we know they're close.
They're in Walsh County, which is the county that's on the border right above Grand Forks. And we do know that they're relatively proximal in Minnesota. If you're that close, the river does not make much of a barrier for an insect that'll fly. Have some links in the chat and if folks do want to look up a article that just came out last week, Minnesota Crop News, this type in cereal leaf beetle.
And you should see the article there too, that'll have more information on what we look at for scouting thresholds, But what are the options we have for insecticides for this insect and how well does it work considering you have that mucus layer on that? Is that affecting Fc at all or the insecticides working pretty well? Well, most of the insecticides that I saw you got fairly good. When I went onto the arti trials, most of the pyrethroids seem to be working fairly well.
There wasn't a lot of resistance being recorded with this insect. And the other one is if there are certain amines that are also available. But I think that might be overkill if the pyrosis are working, you know, that's the low price point and they seem to work well. So that would probably be the first thing to go to. All right.
I think we will move over to Bruce and some of the other insect issues we have, but we'll definitely come back to you for Northwest Minnesota because I think we'll talk about some dry season insects and what's also happening with that, because again, showing up some parts of the state likely to show up in more counties this coming week here unless we get some rain, there definitely are some insects or keep an eye out for first.
We've had a lot of calls about true armyworm the last week or two, At least some of these are ones where they're wrapping up. There may not be as much they can do about it, but what have you seen for true armyworm? Caterpillars are getting calls in that both for concerns about what's in our field crops but then also what's happening in pastures too.
Because there's been apparently a few calls coming in Southeastern Minnesota, especially where folks fed close to maybe 50 larvae per square foot in some well, I mean, we've been worried about army worms and black cutworms all spring, we run some pheromone traps and light traps for both of those insects. And in the Southern part of the state, when we had those heavy rains come through, that those were systems that brought migrating insects in from the south.
I haven't I think I was on one of these previous webcasts, but, you know, I cut my personal record for army worms in a single night and a light trap that was 195. And then quite a few of the following nights, some pretty big flights have come in on both species. We've had injury to a lot of injury to pastures and grass, hay land, that sort of thing, But also in corn, particularly where corn was planted into rye. And I think we've had people alerted to that.
They should have been out scouting both of those areas because of the high flights. I think the thing to realize here is that we've got, we've had a perfect storm, especially in Southeast Minnesota where it's dryer. We had weather systems that brought a lot of mass in. They were looking for dense grasses to lay eggs on in case of army worms, whether that be a ry cover crop or some sort of perennial grass. Then we had a dry conditions set up and that slowed crop growth.
Those larvae ran out of food quicker and they were encouraged to move faster. And that's where they get the term armyworm. When they run out of food, those larva move in mass. That's what we're dealing with right now. There's been multiple flights and we've got quite a range of arable sizes out there. And we're going to have some issues here for a while. And it's not just Southeast Minnesota.
I know they've had some bigger flights up into Northwest Minnesota, so we're going to have to keep an eye out for at least the next few weeks. Yeah. That was actually one of the questions I had was how long we really need to be keep an eye out for if people are seeing an issue right now. When and where should they be treating? If we're talking about field crops, corn, how long is that susceptible for if they have grass edges. But then also Pastures?
When is it economical to treat pastures, especially in these stroke conditions? Is that something where if you see high numbers in your pastures and you're already on age out there, is that something you need to be out there ahead of treating pretty heavily or is it a little bit difficult, especially if some of these larvae are more mature out there? Well, I think really if the guys are wanting their hay crap, they want to protect it from the insects taking it.
The threshold is the same for grasslands and hay ground as it is for small grains, four or five larva per square foot. I think the other thing that happens is movement out of those areas, kind of similar. I think maybe I'll talk about grasshoppers later on, but you don't want the larvae to move out of those areas into, into your field crops, either, particularly corn. And so I think, you know, treatment should have happened in some of those fields earlier.
Some people didn't find the problem in their hay ground until they were out there mowing. But I think I think definitely treating the treating where these larvae are starting from is a good idea, or at least a border on those areas before they get into the crops. Row crops. I think you mentioned black cutworm earlier too, what you've been seeing happening with that? Well, we've had some pretty significant issues.
Some of the Southern Minnesota beet growers have had quite a few have had quite a struggle with cutworms this year. Some of that's the same situation. A lot of guys are planting an ot cover crop to prevent erosion that's a little bit attractive to the mass. Then when they kill that oats, they'll move to the sugar beets. And small sugar beets don't stand up to cutworms very well. It's multiple species of cutworms in the beats.
Actually we've had some variegated cutworm issues or some of those in L Flp as well. Again, another migrant and I just got a picture last night of yellow striped army worms and sugar beets. It's definitely a year for migrating moth insects. I think something we're going to have to keep an eye on, particularly with this drier weather. Some of the diseases aren't going to help control the insects as well. I've had a few other questions come in and is reminder to folks too.
You can use the Q and A if you have any questions, if you're on the, um, chat itself here, but swiping glitch, are there any updates on that one Or is it too early to be able to tell what the situation is looking like this year, where fines might be showing up, or severity was down at our research site in Rock County yesterday afternoon. And we've been monitoring emergency cages, and I think the populations were are fairly low again this year.
And we didn't haven't picked up any in the emergency cages, but we do have some plants being infested. Now, there's a few orange larvae, so they've been there maybe a week or more, but most of them are still fairly small. First, in stars, that infestation is going on right now. Okay. I think people are going to be asking about safe. We'll try to have another session on that coming up here soon. But yeah, it sounds like slaved, that one has been showing up.
Some people are finding in fields but obviously not threshold levels yet. A little too early for that one there. But the main question I'm getting here is on grasshoppers. Both Bruce and II can hand that one off to both of you here depending on what you're seeing. But I know I'm seeing plenty of small grasshoppers and some of the hay fields out here. Not anything too concerning yet in West central Minnesota, but high enough populations. Now, I definitely want to keep an eye on it.
Is that the situation? You both are seeing your neck of the woods or are you actually getting pretty high numbers out there? I'm seeing really high numbers in alfalfa, red legged grasshoppers. And it makes sense. At least in this area. We've had two years of drought, dry weather, actually severe drought. So I think that's something people should watch.
And again, it, it's a case where if you're seeing those nymphs in these production areas that hay or grasslands next to it keep an eye on that because they probably won't stay there. Yeah, I concur. I don't think our populations are as high as Bruce is seeing down in the Southwest, but we are starting to see stuff in the Northwest. Like he says, we're starting to see nymphs. I've had calls already, which is early in the season.
I think we've probably had a little bit more rain in the fall and maybe a little bit more early spring. Our populations might not necessarily be as high. Certainly the recipe for grasshopper populations, any years or dry fall followed by a dry spring is going to give you grasshoppers. Um, like I said, we're probably not as high as Bruce, but yeah, that's something people should be watching and scouting for.
Hitting the edges of the fields and seeing what their populations are, like something that should be on their radar screen. Yeah, that's a good reminder for folks. I think we've hit on it a few times over the years here. But grasshoppers are a dry season pests. Partly just because when it's wet, you have more mortality due to fungi that might go after grasshoppers. Bruce, you want to talk a little bit more about those conditions. You know, when they do well versus why they don't do well.
Then the worst thing, and I want to a comment here, it's not every field in every area that's got grasshoppers. It depends a lot on the previous year's weather and particularly last fall and this early spring. But the worst thing for grasshopper nymphs, and I think correct me if I'm wrong, is when those nymphs are hatching. If you have a cool, wet period, there's two things that happen. One is disease. One, it's too cold from, to move and they starve to death. We haven't had that this spring.
Species I'm seeing right now are species that tend to hatch later like the red leg stripes. And I'm not seeing much of all at all. Yeah, I think our populations are a little heavier for two stripes up here than down there. They're a little bit more common. And that could be also because the red lakes have a tendency to prefer that warmer drier climates than the two K two stripes. But we used to get a lot of red lakes down in high plains in Colorado, so that's why I was thinking that.
But yeah, Bruce is 100% right there. The wrong conditions for grasshopper at the early season and when they're hatching out is a great condition for us. You know, they're very, that's by far the most, it's by far the most sensitive stage in their lives. They don't know when they're emerging. If they don't find food within a meter, they're probably not going through.
So and that's one of the reasons why those, you know, those hot dry springs are if it's followed a hot dry fall, you can start to see hoppers. But if you've got that cool period and it's moist, the fungal diseases are going to take off. As Bruce said, that's going to have a lot of mortality on the young. And as he said, moving is critical. They've got to feed. There's not a lot of resources, food resources, nutritive resources, and a grasshopper egg.
And so they need to take on calories pretty quick. And if they can't move or if it's bare ground or something, they can't get to food, it's going to be pretty tough for them. So we've been talking about forages a bit here, especially on the army worm side. And that applies to grasshoppers, we're finding a lot of it. How about soybeans though? When is that a more acceptable crop? Are we looking at that later in the season or do we have enough defoliation now? We'd be worried about our soybeans.
For grasshoppers? For grasshoppers, yes. Well, I think is more two stripes up there in Northwest Minnesota. Northern part of the state down here. Those are replaced by differential. They are larger grasshoppers. The differentials hatch later, but differentials and red legged particularly will lay eggs and soybeans, especially if they like firm ground, bare ground. So no tail type situations are preferred that alfalfa is perfect for them because there's a lot of bare ground in amongst the plants.
Um, and I think the other thing to worry about, not so much on grass hay but on alfalfa, is blister beetle larvae feed on the eggs and if you've got high populations of grasshoppers in those alfalfa fields laying eggs, you have a tendency to pull in blister beetles. And then now you've got an issue for hay quality, particularly with horses. Actually, we've gotten some calls on those blister beetles up. We've talked about that on our crops calls before.
And yeah, I've had some fields who I've seen the great blister beetles showing up in alfalfa on the edges in central Minnesota. And if you have the beef cattle, they're a little more tolerant to that. But yeah, like you said, horses, that's more of a concern there. The take home was with blister beetles. And this can be our wrap up question here for folks. That's one where we're saying that if you're going to mow, give it some time for those beetles to disperse.
Don't be crimping it or spray insecticide because that's a case where you just have the beetles left in the hay and then you're going to have that irritant from the beetles that's going to get into the livestock a lot easier because you're just going to have more beetles out there or Bruce, do you have any other thoughts on those blister beetles and what they're up to in the fields? Just be aware of Yeah, I can catch people off guard a little bit.
I think given by the calls we're getting in here, don't let that Alp alpha Bloom because that'll congregate them in the field as well. All right. Well, I think that we're about time to wrap up here. Again, thanks everyone for attending today's Field notes program. We want to, again, thank our sponsors, the Minnesota Soybean Research and Promotion Council and the Minnesota Corn Research Promotion Council. Thanks to Bruce Potter, Dr. I Mcrae, for joining us this morning.
And have a great rest of the day, everyone, and we'll see you next week.