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Join the University of Minnesota Extension Crops team in addressing all your crop-related questions this growing season, from soil fertility, agronomics, pest management and more. We will tackle issues as they arise to help you make better crop management decisions this season.
I'm Ryan Miller, Crops Extension Educator. Earlier this morning, we recorded 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 8 AM on Wednesdays throughout the cropping season. During the live webinar, participants can join in the discussion and get questions answered.
Ryan Miller:An audio recording of the live program is released following the webinar via podcast platforms. Thanks. And remember to tune in weekly for a discussion on current cropping and crop management topics.
Claire LaCanne:Welcome to today's strategic farming field notes program focusing on insect updates and management considerations. These sessions are brought to you with, by, with generous support, by the Soybean Research and Promotion Council and the Corn Research and Promotion Council. And we're happy you joined us for today's session. My name is Claire LaCanne. I'm an extension educator in crops out of the Andover Regional Office.
Claire LaCanne:And we welcome Bob Cook, who's our extension soybean entomologist, Doctor. Fei Yang too, our extension corn entomologist, and Bruce Potter, who's our extension integrated pest management specialist. So with that, I'll kick us off here by asking the 3 of you, you know, just to kind of give us a quick overview of maybe the effects of our low our warm, moderate temperatures this winter, kind of the effects that the current rain situation in many parts of the state might be having, and kinda just a quick overview of what's going on in relation to insects and the state of affairs across the state.
Bob Koch:Hey, Claire. Maybe I can take a stab at this first, and then Bruce and Fei can chime in.
Claire LaCanne:Yeah.
Bob Koch:You know, insects are affected differently by different weather conditions and things happening at different times of the year. If we think back to the winter, it was pretty mild overall, so that probably, helped a lot of insects that spend the winter here fare better or survive at higher rates. But then this spring, as we know, we've had some pretty severe storms, lots of rain, and that can have a couple different effects. Right? As these, weather patterns line up, sometimes that can help the migration of some of the migratory insects moving from the south to the north.
Bob Koch:But then also all these hard rains and cooling water, can certainly take a toll on, you know, maybe survival of some insects that live in the soil or pests like the soybean aphid that are trying to move from buckthorn to small soybean plants, all that rain can reduce their survival and their ability to, to establish colonies on the soybean plants. So for soybean aphid, in particular, you know, I think they probably did well over the winter, but like I was saying, you know, I I think in areas where we had real heavy rains, which was a lot of areas, it probably decreased their their survival on these small soybean plants, but soybean aphids have a real high reproductive potential, lots of generations. You know? So there is still potential that they could could bounce back even if they were set back. So, you know, I kinda go to the default response where we need to be scouting.
Bob Koch:Some of the fields I'm seeing in Southeast Minnesota, you know, we certainly have aphids there. I suspect we're doing a lot of other areas, and, you know, what's what's a little concerning to me is in some of these fields, there's already a high percentage of the plants that are infested with soybean aphid. And it seems like as we get more plants in a field infested, then they're you know, after a while, their their, ability to increase in numbers really increases. I'll let Bruce or Fei, you know, time in on corn or or some other aspects of how weather, you know, might be affecting some of these different insects.
Fei Yang:Yeah. For congruent worm, like, they we have, like, a really, like, a warmer winter this year. So the eggs probably they have got a very, very good survivor during the winter. And, this would be a hop build up the population of populations. So if you plan to, like, earlier, like, May or late late April, I think that's the first, like, a planting window time.
Fei Yang:And probably you will have some good, like, like, having infestation over the rootworms, but as as mentioned, like, the weather run now, like, you you have a lot of rain. So a lot of, like, the cone or the soil was saturated, so lots of water over there. And then this will have bring down some, like, populations of the root worm, but I think the damage is already over there. So we still have, like, a severe damage, and then we test some, field trials in, in, like, on the campus, and then we check some times and we found, like, a severe damage of the con roots by the con root wall. So in general, we have some good winter weather to support the survival of the rootworms and we have recently, we have too much to cure some probably the egg and also the larvae, but the overall population for rootworm is still over there.
Claire LaCanne:Yep. Thanks for that, Fei. And, Bruce, you are in a particularly wet part of the state over, southwestern Minnesota. So you mentioned you've been seeing some probable corn rootworm drowning and
Bruce Potter:you know what? Over the last week, I took a tour through, a lot of Minnesota. I got, over as far as Waseca and and, all the way through Southwest Minnesota, Southern Central, West Central Minnesota and there's, it's wet all over. And, in some areas it's, it's, you know, pretty, pretty distressing. We've got a lot of drowned outs and stunted corn.
Bruce Potter:And, you know, if, like Fei was mentioning, if the corn plants are dead, the rootworms on them, if it if they died reasonably, early, those rootworms are dead as well. If they're if they're submerged for 24 hours or more, you know, the warmer it is, the shorter they can survive. We're gonna have, they're gonna drown. They build up lactic acid and drowned. But Bob mentioned something too about, you know, migratory insects coming in and what kind of weather we have once they arrive.
Bruce Potter:We had huge, and we talked about this earlier in the year, year, huge black cut room flights come in bigger than we've had in many years, but the damage wasn't, wasn't as significant, as I expected. And and I think 1 of the reasons for that is those laws tend to lay their eggs in depressional areas, and a lot of those went underwater. It's particularly early in the areas where we had those heavy flights. So, we cannot survive the bullet there. I think we've got soybean aphids here but they're on little islands where the soybeans have not been sitting in water for a long period of time, better, better growth.
Bruce Potter:And then the other thing, the only thing that kind of matched, what we expected, as far as overwintering so far has been alfalfa we will so seem to do do just fine.
Claire LaCanne:Yeah. We had some significant infestations of those across the state, didn't we, on the alfalfa weevil side? And you'll monitor for armyworm too, Bruce. What have you seen? What do you have to share with us?
Bruce Potter:Well, traps have been been pretty low with the exception of, some traps up in Roseau County, but yesterday I got some reports in, from northern, west, central, southern end of the valley where we've got some some pretty bad armyworm damage and a few wheat fields. So, those kind of snuck around the snuck around the traps, but, you know, basically this time of year, if you've got wheat or you've had corn planted into into a rye cover crop, you're probably it's probably a good idea that they'll be checking for that insect.
Fei Yang:Yeah, Bruce. Like, in the early season, we did some seed corn markets, like, trials, and then we see, like, a little bit, like, we cannot say high, like, a moderate infestation in some of our field trials.
Bruce Potter:Yeah. It was a good year for seed corn maggots and and, planning and planning dates and and, fly activity kind of mashed up in a lot of cases and and, they were getting around some of the seed treatments as well. So, I think part of that too is, is, you know, just so much water that, you know, we moved that active ingredient away from where the where the feeding was happening.
Fei Yang:Yeah. For we we did several trials. So for our first trial, we see, like, a moderating infestation, but for the second and the third late planning trial, we didn't see too much infestation. Yep.
Claire LaCanne:Okay. What do you just to remind everybody here, like, what do you do to Gordon Magit?
Bruce Potter:What what was the question, Claire?
Claire LaCanne:Oh, just how can people manage seed corn maggot at this point?
Fei Yang:So what we did here, like, we we did lots of, like, seed treatments using, like, neonictine insecticides. So that provide a very good control for this, silicone markets if the population is not very high.
Claire LaCanne:Neonicotinoids did? Yeah. Okay.
Bruce Potter:I better The other thing the other thing too is, is kinda watching and, and those models are on the extension or on the university website, and kind of looking for when those that fly those flies are active. And then you're at high risk if you're planting, into something that's been manured or green manured or, during that period. And it's kind of a just just moving your planning date around a few days makes a big can make a big difference like Fei was mentioning.
Fei Yang:Yeah. Based on what, like, a different planting dates, we see different, like, infestation levels.
Bob Koch:So, Claire, so there there's not too much you can do after you discover testing. Right? So it's Right. Thinking about the risk of particular fields, you know, different things that might make that field attractive. As Bruce mentioned, the degree day models for timing planting and then different, preventative insecticide applications like like the seed treatments.
Claire LaCanne:And it's a good reminder that we have those degree day models available online and some forecasting tools at the university too. Take a look at those. So, yeah, well, going back to corn root worm, Fei and, and Bruce too, we had a question coming before our episode here today, from an email wondering about just the observations of corn rootworm feeding across the state. Do you have any updates on that? You mentioned your trials.
Claire LaCanne:Bruce mentioned, you know, some of the drowning, but, what are you seeing feeding wise?
Bruce Potter:Well, it's it's it's out there, but I think right now, you know, we're getting close to the time where we can kind of gauge how bad that damage is, is gonna be. We've still got larvae out there. We've still got some root feeding. But I mean, if guys wanted to start getting an handle on things, you know, they could they could do some root digs and some root floats and see what kind of larvae are out there and what kind of damage we got, but but that damage is I would expect it to continue to increase for a little while.
Fei Yang:Yeah. Because most most of the egg should hatch, like, in June, so leave a feed on the roots for about, like, 4 to 8 weeks. Right now, probably, it's late in stuff because, like, a rootworm lab egg, maybe I experienced, like, 3 different instars. Probably right now, it's a certain instar, and, you will see probably 1 or 2 weeks. A lot of be like, beetle is emerging in your fields.
Fei Yang:So as Bruce said, the best the best option is to dig your roots and a retail damage, and then you can see, well, how about, yeah, like a management strategies, how how it works this year for this season. And also later, and then you can put some yellow stick traps and also you can use like whole plant sampling for beetles. So you can predict the populations next year and to see what kind of management strategies you can use for the future. You can use different insecticides, see see the treatments, and also you can choose like a different BT traits based on your field history. And also like a root worm is very like a local.
Fei Yang:So fields, like, even very close, so they are totally different. So you need to manage, like, determine your management strategies totally based on your field characteristics.
Bruce Potter:I think I think the important thing to know about remember about corn rootworms is right now, unless you're in a rare situation where you've got, you know, pre pollination, silk clipping, which is actually pretty rare, You know, right now we're managing for next year for roadworks. I mean, all our options for this year are over, and we're looking at, how well what we did worked and what as Fei mentioned, what what to do for next year.
Claire LaCanne:Yeah. That's a good reminder.
Bruce Potter:Is fun, but it's not. It's pretty expensive.
Fei Yang:Yeah. It's a $1, 000, 000, 000 it's a $1, 000, 000, 000 box, so it costs lots of damage for and also lots of cost for managements. And that because like a root worm, it seems like it can overcome airy, like, a management strategy. It's developing resistance to catch propagates insecticides, BT traits.
Claire LaCanne:Yeah. We had a question about, insecticide resistance in corn rootworm too, Fei. So, do you have any resources or tools you want to point people toward maybe for for looking at what what treatments are still effective, which Bt traits are still considered effective?
Fei Yang:So in Minnesota, we have 2 different species of rootworm. 1 is like a western con rootworm and the 1 is northern con rootworm. So the western congruent worm, it seems it developed resistance to almost every strategies. For insecticides, parasitories, and, Bt traits, CRIS3BP1, CRIS3 phosphide AB1, but the only thing we have right now may may be working for Western conodal worm is eye eye technology. That's new.
Fei Yang:But it is with all the BT traits, like, is auto it is auto efficacy so that we have put II as a single trait. So if the insect project is high, it can debug resistance very fast, to I and I for western congruent worm. And, also for northern congruent worm, the resistance, it seems not that widespread like, in the state. But we had I think they published a paper late last year, and they found some cases for northern congruent developing resistance in Minnesota in Meico County to crossly bb1 and the crossly for SIFA ab1. That's the first report for, northern congruent developing resistance within the state, and except for that, I think, like, several years of pagoley found, like, a feared population sharing resistance in our neighboring, like, state, like, North Dakota, and they reported like unexpected survival of the northern congruent worm to crush the bp1 and the cross site phosphide bp1bt traits.
Fei Yang:So right now, the population of Northern is increasing and, with the development resistance to both CRYB we b b 1 across the phosphorab1bt proteins. That means we we need to pay attention. So we need to sample some, beetle this year, and then we can test the stability, like, across the state to these BD protein proteins to get a general idea about the population, like, status against the b t traits. Do you have any do you have anything to add, Bruce?
Bruce Potter:Well, I mean, as far as insecticide resistance, you know, I don't think there's been anything documented in Minnesota, but, for guys that have been doing a lot of, beetle bombing, trying to control adults, I'd be a little suspicious because there, there is resistance to beetles, just over as close as Nebraska, to a lot of different foliar compounds, including the pyrethroids. So, think about rootworms, if you do things often enough to them, they'll develop resistance and it, it doesn't take very long. I think we're seeing BT resistance. It's it's been always about 4 or 5 props and and, they seem to enough of them seem to get around the trait to to cause problems.
Fei Yang:Yeah. Another scene I want to add, like, is not resistance, and we did some, like, competition studies between for the lobby between western and the northern Congo worm, like, in the greenhouse settings. And we've we we did a 2 trials and I experienced now almost like 1 year. So each experiment takes about, like, 4 months is and we found the results were very consistent. And the western conodal worm is more competitive compared to the, like, northern conodal worm.
Fei Yang:So with the so only difference here is, like, the northern conodal worm, they they can over they have, like, a more competitive to, like, a code tolerance compared to western conodal worm. However, if if like last year and maybe future, like, a global warming or climate change and if the temperature is okay, so western canyworm, they may expand the population to the north and that will increase the challenge for rootworm management because, as we mentioned before, western corn rootworm developed resistance almost to every BT traits.
Claire LaCanne:And that's not great news, but, Bruce, you have a tool that I I've seen you share a lot, that called the handy BT trait table. So we can maybe log that into our resource sheet to share with listeners too.
Bruce Potter:Yeah. It's a, it's a good tool. And, and, you know, as we mentioned armyworms briefly and, and in corn, there's basically only, 1 of the BT traits, the BIIP3A or Buptera trait that that's effective on on true army worms. So, that that table's real handy and it's also got a list of, attached to it, a list of known resistance issues. So it's pretty good it's pretty good resource.
Bruce Potter:I can't keep them straight probably because of my advanced age, but I can't keep the thing straight. And, I use that use that resource all the
Bob Koch:time. That's put together by Chris Daphonzo, right, at Michigan and someone from Texas?
Bruce Potter:Paul and Pat Porter. Yeah. Chris and Pat. But mostly Chris.
Claire LaCanne:I won't comment on the age, but I use it a lot too, Bruce. Yeah. I, this is kinda changing gears a little bit, but we can address some of the questions that came in on email. There were questions kind of around cover crop and cover crops and, insect interactions. And so there, there was a question specifically asking, do cover crops help break pest cycles in a corn and soybean rotation?
Claire LaCanne:Bruce is shaking his head. I think I
Bob Koch:hear Bruce, shaking his head there. I I don't think I'm not aware of any situations where we could probably break a best cycle in in Minnesota. There there's some data where like, in soybean, for example, you know, we've seen where if you plant soybean into, into, say, a rye cover crop, you might end up with less soybean aphids in that soybean that's growing with the cover crop than in soybean without. But, you know, you've got other issues there too with the, 2 crops potentially competing, you know, if the, the cover crop isn't terminated at the right time. So there's a chance where you could get a benefit, but it having these cover crops in the system, it, you know, provides all the other benefits that that people know about, but it does create some situations where past risk is increased, and Bruce mentioned that.
Bob Koch:You know, if you're planting corn into, into a grass cover crop or something to that effect. I think the risk is highest, you know, the as as that main cash crop and the cover crop, the the more closely related those are. Right? So corn and some of these small grains, they're pretty closely related. You get a lot of some of the same pests can feed on both of them, so I think there's higher risk there.
Bob Koch:This year, I, saw a situation where a farmer had some alfalfa mixed in with the cover crop and was gonna put it into pasture, but at the last minute, decided to put, soybean in that field, and there is a pretty huge infestation of alfalfa weevil on that alfalfa before planting the soybean. And after terminating the alfalfa, those alfalfa weevils moved over to the soybean and are actually doing quite a bit of feeding there, and I've never seen that before and haven't really seen that reported in the literature other than, you know, a few couple, like, laboratory studies saying it's possible. But, again, you know, alfalfa and soybean are fairly closely related, so it's not a huge surprise that you can get some of those pests moving over.
Bruce Potter:Yeah. So it's just 1 I think the the best way to look at this is the only way to break a pest, you know, overwintering pests in a crop is to not grow the host. And with the cover crop, you still have the host in the host plant in the field, whether it's corn, it's corn, soybeans, or whatever. So you're not really, you're not really giving the field a break from that host crop. So you're not, you know, you're not gonna solve a root worm problem, for example, doing that.
Bob Koch:Because it's not a true crop rotation. Right, Bruce?
Bruce Potter:Right. Right.
Claire LaCanne:Kind of a follow-up to that. There was an email asking, has there been an increase in insect concerns from growing cover crops? And I think, you know, you kind of touched on it, Bob, that is, is there, if you're growing kind of similar kind of same plant family ahead of your cash crop, right, a rye cover crop ahead of corn or a alfalfa ahead of soybean, there's probably increased reason to scout right there to, probably increased management. And maybe just in general with cover crops, we know there's increased management and probably prompting to scout more. Like we know Bruce with armyworm being prob the eggs are laid in a rye cover crop or grassy cover crop or even grass weeds in the field, and then they'll feed on corn after that.
Bruce Potter:You've personally seen the impressive results of that. Yeah.
Fei Yang:Yeah. Those, like, a cover crop will be attract lots of micro like a black cutworm, to armyworm, and for even for armyworm, it depends. So to those, like, cover crop. And so the timing for the termination is very important. So if you terminate, like, earlier and you later plant for the spring planting, maybe you can kill the population.
Fei Yang:Yeah.
Bruce Potter:And I guess 2
Claire LaCanne:Go ahead, Bruce.
Bruce Potter:I was gonna say there used to be there's there's 2 ways to get, armyworms into corn, and 1 is to have a bunch of uncontrolled heavy infestation of uncontrolled grassy weeds. And the other way is to plant a uncontrolled infestation of grassy reeds as a cover crop. So
Claire LaCanne:Yeah.
Bob Koch:But, you know, even though we're saying all this, there's no guarantee that No. Using a cover crop Yes. There's no guarantee that it will cause a problem. Right? It it just increases the risk.
Bob Koch:And as Claire mentioned, you know, III totally agree that what what we should do then is be scouting that field, you know, paying attention, you know, to these potential paths. And I think, Bruce, I've seen in some of your slides, and I can't keep track of all the traits and stuff. But for some of these pests, you know, if if you're concerned about corn, for example, you might consider certain traits or something that might be Right. More effective against some of these other caterpillar pests that that might be more likely in that scenario.
Bruce Potter:I would I would plant I would plant something with that BIP 3 a if I was planting corn into rye, especially especially if I wasn't getting to get the rye terminated real early.
Claire LaCanne:And there's some literature out And I think Bob, you've done some studies too, kind of looking at presence and effectiveness of like natural enemies too, when you have a cover crop that maybe there is some, some correlation, some attractiveness of cover crops for, for getting those beneficial insects in your fields too. But time flies when we're talking insects. So I have a couple more questions I wanna make sure we get to. Any emerging technologies that are showing promise that came in from an email?
Bruce Potter:Fei, you wanna talk about the new traits?
Fei Yang:Yeah. So so 1 thing, like, for, the current commercialized management for root worm is the INI technology. So this technology is not used alone. It's we call it like a pyrimidine with other BT traits with a Crested bb1, and that's a vt4 pro. And, also, we have, like, Smartstack Pro.
Fei Yang:It the the II technology is used with together with, like, a Crested bb 1 and the Crested itself. So
Bob Koch:Okay. I think you muted yourself. You did.
Fei Yang:Sorry. So the ion technology is used with the crusted bb1, crusted phosphide bb1, these bb proteins. They can have, like, provide much more like a mode of actions to control the root worm. So that's a new technology and also there are several technology underway. So like several technology from Bayer and, from Corteva with like a CRY75AA and also VIP4 and also IPD, I've I've got numb the the serial number.
Fei Yang:So those IPD is from Corteva. So those 2 technologies is under registration. So maybe they can bring some new model of options for management of root worm in the future. And also a new stuff like I'm working on right now because like we use like we try to see whether silicon rocks, those are used to capture like carbon dioxide. So those can increase the the boost boost the plant health.
Fei Yang:And, also, because, like, you know, like, rootworm larvae is attracted based on C02 released by the root. But those those silicon rocks can absorb the C02, and this may disrupt the behavior of the root worm larvae to target the roots. And also, as I mentioned, those silicone rocks can boost the plant health. They can make the plant to be more tolerant to the damage, so maybe they can provide some protection for the yield. So we are working on these right now.
Fei Yang:So these are new some new information, new technologies in the future.
Claire LaCanne:Thanks, Fei. We'll we'll stay tuned for that. And 1 question we got an email that caused all of us to kind of do some looking and researching prior to the program is, can clarpurifos be used to control red sunflower seed weevil and sunflowers in Minnesota? And we think partially why this question is coming up is because of the the status of chlorpyrifos where it was right revoked, by EPA for a while. There's, kind of temporary use allowed for certain products back in Minnesota.
Claire LaCanne:So right now there's 4 products that are allowed in Minnesota, 2 that are foliar products, and, we can kinda share information. I put some of that information in the resource sheet, but the short answer is no, those products aren't currently usable in sunflowers. Right? Bob and Bruce, do you wanna kind of touch on which crops are going to be allowed for chlorpyrifos moving forward or at least the, the best current news we have now on that at at least.
Bob Koch:Yeah. So again, III don't think we have the perfect understanding yet, and we're gonna reach out to our colleagues at the Department of Agriculture to, you know, maybe put out a crop news to clarify some of this. But, it sounds like toward the end of June, there was, an EP announcement that came out potentially reducing the number of crops on which these corporeal products can be used. And what was it? Narrowed down to 11 different crops.
Bob Koch:I don't have that list in front of me, but it from what we can tell, it looks like sunflower was removed from that list, but I think things like alfalfa and soybean and maybe wheat still remain for Minnesota. Is that right, Bruce?
Bruce Potter:Yep. And sugar beets, Then some vegetable crops and fruit crop.
Bob Koch:But we're going to, like I said, get in contact with the folks at the MBA and try to get, some better clarification here and get that out on crop news so everybody has the most accurate up to date information on what they can or can't do.
Claire LaCanne:Yep. Which crops it's usable on, which, again, which products and then, what pests they're labeled for is all good information to know. And I think you're saying too, Bob, if people really question, they can also check directly with Minnesota Department of Agriculture, you know, before they make an application too. So well, we're at the end of our program. Any parting thoughts from anyone?
Claire LaCanne:Bug, you do have a bug joke or anything, Bruce? You're usually good for something like that.
Bruce Potter:No. I well, I know it's, I wasn't a better mood. We've kinda missed a lot of the rain here at Lamberton, but, that changed this morning. So my plans for the day are are are completely different. It's you know, I think we drowned some more rootworms if anything's come out of the roots to pew, to to, pupate or to, mold or something like that.
Bruce Potter:So I guess that's positive.
Claire LaCanne:Yeah. There we go. Alright. Well, thanks again for being here today and, we appreciate your insights and discussion and thanks everybody for attending the program. Again, we want to thank our sponsors, the Minnesota Soybean Research and Promotion Council and the Minnesota Quorum Research and Promotion Council.