Field Notes talks weed and insect updates
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.
Anthony Hanson:Welcome to Strategic Farming Field Notes. This program from University of Minnesota Extension. It's brought by generous support by Extension Program Extension Programming, but then also by our sponsors, Minnesota Soybean Research and Promotion Council, as well as the Minnesota Corn Research and Promotion Council. So we're going to go ahead and join us for today's session on essentially early season weed and insect planning, where we can figure out what's going on with current spring conditions and how to react to that with what we're seeing for some of our pest pressure out there. I'm Anthony Hansen, regional extension educator in Integrated Pest Management, and today we're welcoming 2 guests.
Anthony Hanson:Our first is doctor Debalin Serangi. He's our Extension Weed Scientist with University of Minnesota. And then we also have Bruce Potter, our IPM specialist in Extension, who who's gonna talk a little bit more on what's going on the insect side of the world in terms of pest issues we're running into. So with that, I'll turn it over to Devalin. We'll start talking about what's going on with our wheat situation a little bit.
Anthony Hanson:So, Debalin, one of the questions I know you've been getting a lot and, any of us who've been out in the field this year, we've been seeing kind of a spread across the state. Some people got in, planted really early or relatively early, maybe about more than 2 weeks ago. Some of us planting has halted a little bit. I know in my neck of the woods here, West Central Minnesota, we've had nearly 4 inches of rain in the last 2 weeks. That slowed things down a little bit.
Anthony Hanson:So when we look about at our wheat situation, what is that kind of disjointed planting gonna mean for decisions farmers are looking at depending on when they got their crop in?
Debalin Sarangi:Thank you, Anthony, and good morning, everyone. Thank you for having me. So, that's a very interesting question that I'm getting from last 2 weeks because, few people planted their corn and soybean, as you said, like, 2 weeks back probably. And then they got, plenty of rain and moisture. They're now concerned about their preactivity because we need rain for pre activation.
Debalin Sarangi:We got that rain. But now question is how long that pre can stay in the soil to control the weeds, especially if your target weed is, waterhemp. Because waterhemp does not emerge, Like, earliest you can see, waterhemp emergence would be maybe May 10th ish. So you you are looking at 3 weeks gap from your planting to water em emergence. So, that's a question I'm getting from the people.
Debalin Sarangi:And then few people, due to the rain, they could not plant yet. So they're on track now. They are probably planning this week or next week. So they're asking me, okay. So I saw some, lambsquarters are up and waterhemp started coming.
Debalin Sarangi:So what will be my herbicide program? So it's like, not one suits fits all situation. You know? So for the early planter who planted already and put your pre, yes, there is a chance that with that rain, preactivity would be really good. But usually, we say the preactivity lasts for, 3 weeks to 4 weeks.
Debalin Sarangi:So if you're using a really nice pre to control your weeds, 3 to 4 weeks time period that you were looking at. So your pre will run out of fuel pretty soon, so you have to plan your postemergence, very early because, I have been in a field, last week, last Friday, in Rochester. It's a farmer's field. He planted 2 weeks back, and he put a pre. And now I started seeing some lamb's quarters started coming.
Debalin Sarangi:So it's been 2 weeks. It started coming now. So my recommendation for this situation is plan your postemergence herbicide early and, maybe in your postemergence tank mix, throw some kind of, chloroacetamide or group 15 type herbicide like dual, outlook, or warrant. So that will give you a little bit more extended period for a residual control for your weeds because, the, the early planted corn or soybean, it will take some time to close the canopy. So you need a little bit weed free period.
Debalin Sarangi:So the folks who are planning now, they're pretty much on the, same timing for water hemp or lambsquarter emergence. So you should be good if you have a strong preprogram. But I know due to rain, sometimes people are rushing to plant, then, maybe your, sprayer is not following your planter. And some herbicide like, flumioxazin, like valor or fierce type herbicide, those are recommended to spray within 3 days of your planting. So, if you could not, spray your pre within 3 days of your planting, you're kinda off label, and you can injure your soybean.
Debalin Sarangi:So, in that case, I would say check the weather plan properly so that you can plant and put your pre down. So that's that's how you can control your lamb's quarters or waterhemp, which will emerge, pretty soon.
Anthony Hanson:So, Debalin, I know there's been some research in the past at university booking more some of these other weeds, say, like, giant ragweed and others where if you end up planting later, especially late tillage, sometimes you'd knock out some of that emergence. Is that a situation we're looking at this year? How are some of these other weeds looking in terms of when they're emerging and especially when some of these folks planting maybe just this week might be benefiting from that?
Debalin Sarangi:Yeah. That's that's very good question. So this week, this year, giant ragweed is, on track for their, like, timing for emergence. So, usually, giant ragweed you'll see end up April or early May. And I have been in the field last Friday.
Debalin Sarangi:I saw giant raguid is in cotyledon stage. So they're they're up, so they're on track. But the interesting thing is, like, your lamb's quarters and waterhemp, they're coming early this year. So, last week, Friday, I found, lamb's quarters. They're already 1 to 2 inch tall, some of them.
Debalin Sarangi:Some of them are still coming, and waterhemp just started coming. So it is early for waterhemp, and it is probably a little early for, lamb's quarters. But, yes, ragweed, if you are planting now, if you start clean with your tillage, you can control ragweed with your tillage because, ragweed usually stops emerging end of May, and majority of its emergence happened by May 15th. So I would say, like, if you do tillage right now, you can get rid of 50% of ragweed.
Anthony Hanson:Yeah. So that's, yeah, a good point here. A little benefit of late planting. Sometimes people get worried about that, and I was like, no. It may help out for some management issues coming up here.
Anthony Hanson:So one of the other questions I get a lot is what's happening with palmaramaranth? Have there been any updates on that? So just kind of a quick summary what's been happening basis last year, and what are we looking at this year for potential risk.
Debalin Sarangi:Yes. So Palmer Amaranth, situation is, pretty similar. I would say the number of cases reported over the last few years is kind of declining. So that is the sign of the success, of MDA and U of M Extension Driven Eradication Program as well as the effort put by the stakeholders. Because, like we, like we are telling the stakeholders at some point this eradication effort may stop due to, all the fine funding and financial situation.
Debalin Sarangi:So it will be kind of on the stakeholders to identify and eradicate them. So I think our, as a state, our stakeholders are really doing good job, in identifying them and eradicating them and reporting them. So our reports are going down and we I think, if I'm not mistaken, out of the sites we identified so far, I think there are 2 active sites that MDA will monitor this summer, and, there is no new evidence this year yet, but we'll keep monitoring that. But I think our our stakeholders are doing really great job, taking taking the palmaramaranth out and pushing it back from the state coming from the state. Yeah.
Anthony Hanson:Another question, Debalin, is how about herbicide carryover? I know that was talked a lot about this winter, especially when we're in dry conditions, and now it's so wet for a lot of people. Now it may be an afterthought, but is that still an issue for some people? But then also if you get further north, we haven't got quite as much rain up there either. So maybe there's higher risk if you go further north.
Debalin Sarangi:Yeah. That's another very good question I'm getting. So, if you see the trend in last few years, like, at least from 2021 since I have been in Minnesota, I saw every year there are multiple reports of herbicide carryover. If it is soybean, it's from, like, callistotype, like HPPD bleacher herbicides. Or if it is, corn, I'm getting reports of flexor carryover.
Debalin Sarangi:So these are pretty common last 3, 4 years due to the drought situation. And this year, that concern was still there, and it is still there because, we we didn't get much snowfall. We are getting good rainfall now. That's very good thing, but we don't know how the later part of May may look like. Because last few years, if you think, early spring is little wet, and then when you go to later part of the spring, it's pretty dry.
Debalin Sarangi:It's drought. So, yeah, I mean, I cannot really predict what will happen, but there is a chance this may happen this year again. But with this rain, I'm hoping the severity will go down because, lot of herbicide, they need the rain to get, like, you know, like, degraded with microbial activity. But it is a little bit cool. We are getting seventies now, but with a high temperature and sunlight, it it gets, like, degradation get gets faster.
Debalin Sarangi:So I cannot really predict, but if I see the trend of last 3, 4 years, yeah, I may I'm expecting to hear few reports at least this year as well.
Anthony Hanson:Alright. One last question before we move over to Bruce. I know you've had a monitoring project going on the last couple years for herbicide resistance, and that was in waterhemp. Do you wanna give a quick summary of how that's been going? And I know you've actually been finding some pretty heavy resistance in some cases to multiple herbicides.
Debalin Sarangi:Yeah. So, Anthony, that herbicide resistance screening for waterhemp, we concluded that, research actually. So we only screened for postemergence, registers. We didn't screen for any preemergence or residual, registers. So our postemergence screening is showing that Roundup and ALS, like classic or raptor resistance is predominant throughout the state.
Debalin Sarangi:There is no such pocket where it is happening. It's throughout the state. And then if you go come down to, growth regulator auxins, like 240, Dicamba, we found quite a bit of population those are registered. And those population mostly, they are located in the, south and southwest part of the state. So, I mean, I'm not saying the auxin registers or 2 40 registers is not happening in other part of the state, But the samples we collected, most of them came from south and southwest part of the state.
Debalin Sarangi:And then atrazine and Callisto, those are 2 corn herbicide. We got about, 47, 50% population we screened that were registered to atrazine and about 20% were registered to Callisto. And then Flex Stir, it's one of the important herbicide for soybean. And if you think it's a PPO herbicide, some of the sugar beet growers, they started using, Ultra Blazer on their sugar beet with that, special, section application. So we got about 30% population registered to PPOs.
Debalin Sarangi:So only thing right now is our hope is, liberty, glufosinate. And as you know, it's a bit tricky herbicide. You need lot of things to be right to get liberty activated. But if you can preserve that option, it's a very good tool for controlling waterhemp right now. So, I mean, yeah, I mean, 240, we can still use because 2 40 resistance is not prevalent yet.
Debalin Sarangi:Like, it's about 10% population. We can still use 240, but Liberty will be one of the great choice, but we have to diversify our management and to preserve this herbicide option.
Anthony Hanson:Alright. Thank you, Debalin. And, yeah, if you wanna hang around a little bit just in case questions come in on Sure. More weed issues, we can tackle that later.
Anthony Hanson:Bruce, I think we'll move over to you here and chat about what's going on in the insect world. So I know, you, run the black cutworm monitoring network, basically across good chunk of the state there. I'm wondering, what are you finding this year? Are we, looking at a situation again where it's a little earlier season, it feels like? Are we seeing more pressure earlier?
Anthony Hanson:Anything that you're getting indications of with black cutworm. And, also, for folks who haven't looked for black cutworm before, what do you actually do when you're out there monitoring for it in scouting?
Bruce D Potter:Well, thanks, Anthony. Appreciate being, being on the program here this this morning. Well, we've been running this black cutworm network for quite a few years, and, you know, a lot of people think when they think of insects migrating, they think of monarchs, but, there's a lot of other insects that do that as well. A lot of butterflies do things like painted ladies and, and, red admirals, but a lot of, a lot of our pests do as well and, and black cutworms are one of those. As far as timing, I think they're they're pretty much on on time.
Bruce D Potter:It's what what brings these insects into Minnesota is they've got they can move a short distance on
Anthony Hanson:their own, but
Bruce D Potter:there's a pretty efficient transport mechanism setup where if you get a high pressure systems stuck over to our east, and then we get cold air coming off the mountains and a low pressure that's gradually moving from the west. That sets up a pretty efficient pump, and people notice that when we get these real strong south southerly winds. A lot of times, most of the time, some thunderstorms are associated with that, and these insects, are waiting to migrate. They'll fly in case of cutworms, they'll fly up at dusk. They'll pick these air currents, and and they can get from, Northern Mexico to Minnesota in a couple days doing that.
Bruce D Potter:So, timing wise, we're right on schedule. And actually, some of the traps we've had this year, we've had, bigger captures, than than I've seen for quite a while. We had the first capture on April 8th that was in Brown County, and, we had another flight that came through, 16th, 17th, another one on the 26th and 27th. The bulk of those have come along the Minnesota River Valley, Brown, Renville, Redwood, up into Swift County, Nicola County. We've been catching some of these traps in in, Randall County.
Bruce D Potter:I've been catching 26 a night, which we kinda consider 8 a night as a trigger or 8 every 2 nights as a trigger. We've also picked some up now, more recently in Jackson and and Pipestone County, there's also been a capture over in, Steele County, so kind of spread around. And so now that we know we've got, pest come the pest has come up, it's a matter of we can use degree days to help predict the timing on when to scout. These captures kind of give us an indication where we're more likely to find these flights come in.
Anthony Hanson:So I know, black cutworm is one of the one of our main insects to talk about for migratory ones, but there's also another one on the mix, and that's armyworm. Are you seeing much of that this year? Has it been a little quieter compared to last year?
Bruce D Potter:So far, it's been quieter. It's still early in the season for for armyworm. You know, we're catching a few, but they've been singles, in the pheromone traps. You know, we'll have to wait and see if, you know, if, if those populations pick up. We had some big problems with them last year in Southeast Minnesota.
Bruce D Potter:They have had consistent problems, more consistent problems up in Northwest Minnesota Minnesota and some of the grass production fields, to get an insect problem, a migratory insect problem, things like green clover worm we had last year as well. What we have to have is we have to have good populations of insects in the south, then we need the right weather conditions to bring them up here. And then we need, we need the good conditions for them once they arrive. Cutworms are looking for, you know, small weeds, winter annuals, you know, lambsquarters is favorite spot for them to lay eggs. Armyworms are looking for grasses.
Bruce D Potter:We tend to get some problems, especially corn, when that's planted into a rye cover crop. And that some people really are gonna have to pay attention to this year because, that rye is pretty darn dense and and and feels compared to most years.
Anthony Hanson:Yeah. I always like to chime in on that one. Here in Stearns County, we had one field where it was, rye but planted soybean. And, normally, they don't really like soybean that much, but that entire field was wiped out. So that's one where I think that definitely illustrates value scouting.
Anthony Hanson:Just being ahead of that if you do have cover crops like that in just to make sure you're ahead of the insect issues.
Bruce D Potter:Well, the good news, Anthony, is if they had us complete their development on soybeans, they probably, probably died. You know, it's not a good food source for them, but, you know, if they're, if larger army worms are coming off of a grass, into, into soybeans and that's all there is to eat, You know, they'll they'll do they'll have to do some they'll do something.
Anthony Hanson:Alright. So back to black cutworm a little bit. Let's say you get if you're in an area that had, you know, 8 moss per night captured couple times even, what should those growers in that area be looking for? Especially, you know, there are some that planted, like, we're talking about a couple weeks ago. Some are just out planting now.
Anthony Hanson:So what's the, scouting process like for black cut farm?
Bruce D Potter:Well, I think one of the things you can there's a couple things you can do to kind of prioritize, scout fields to scout. 1 is, fields that when when we have a map, moth migration come into the area, if the fields have been tilled already, those are gonna be not, the adults are gonna try to avoid those for egg laying spots. So later planted fields are gonna be more attractive fields that have a history of lamb's quarters, or or or, early season weed issues. And then I think, you know, the other thing, the nice thing about black cutworms, just like corn, we can use degree days to determine when about what stage those, those larvae are at. So right now, most of these flights, their later ones might still be eggs.
Bruce D Potter:The early ones are starting to hatch. We'll maybe start to see some leaf feeding on corn that's emerging, or on or on weeds. You know, if you're out and scouting, you know, for weed issues and and your lamb's quarters start disappearing, that's kind of a clue you might have an issue in there. As far as when those cutworms are big enough to actually cut a corn plant, we're looking at probably about the 3rd week of May for that earliest flight, and we can also kind of project out when they should be, done in pupating. So, there's a lot of cue cues you can use.
Bruce D Potter:The other thing is some of the BTs are are effective on them, especially something with the peptera trait. So How
Anthony Hanson:about, you mentioned painted lady, butterflies seeing some of those and that's, thistle caterpillar, that we get. It's kind of the some people know the pest name. Others know the butterfly. What do we kinda keep an eye out for with that one? I know it's been some years since I saw major major infestation, some areas in soybeans, but that's, something we look for early in the season, later.
Anthony Hanson:When does that one tend to show up?
Bruce D Potter:Well, it the, you know, things they like to feed on are are, composites, sunflowers they're, you know, they'll, they'll go after sunflowers pretty heavily. Those larvae also, moths also not their moths or butterflies. Sorry. The butterflies like to lay their eggs, in soybeans as well. And so the flights that come in early, those, you know, early planted soybean fields are the ones that tend to have the most issues.
Bruce D Potter:There's more than 1 generation, and as that second generation comes off in early summer, you you know, you can have, you can have issues more, more broadly, but the good news is those bigger soybean plants can tolerate more defoliation And when we have a big issue, it's usually, usually on these small seedling soybeans.
Anthony Hanson:Alright. Let's move over to, different crops a little bit. You've talked a little bit about alfalfa weevil and hearing some reports of what's going on there. What's kind of our outlook for alfalfa weevil in the next month or so, I'd say?
Bruce D Potter:We certainly should have we certainly should have had a good, easy winner. I think I don't think the I think the population should be should be doing fine. Later late last week, it's hard been hard to sweep alfalfa with all the wind just like it's as they're having problems getting their pre emerge herbicides on. But, late last week, I started to pick pick up my first weevils moving into alfalfa from from hibernation in Southwest Minnesota. So that'll continue.
Bruce D Potter:I think as people get close to taking this first cutting out, they really need to pay attention to weevil populations, make make some decisions on, do they need to cut a little bit early? Do they need to cut and then evaluate later on for an insecticide?
Anthony Hanson:And that's kind of a good note too on the insecticides. We've been talking lately about pyrethroid or group 3 insecticide issues with alfalfa weevil, and we don't have resistance confirmed here yet in Minnesota, but other states have. So I think that's I don't know if you wanna mention insecticide options, kinda what, tools we have available there quick before we head out for the day
Bruce D Potter:here. Well, I think, you know, the, you know, there's, if you haven't had a problem and and a lot of guys are still trying, some tried it last year and they seem to work okay again. So I'm not sure on the resistance issues. They're steward as well. And I think the other thing that's coming into the mix is is, not just for for other crops as well, is or pure FOS has got the crop tolerances restored and it's gonna be a matter of which products are labeled if that if that can be used.
Bruce D Potter:And and it's gonna limit a numb number of crops.
Anthony Hanson:And I I don't know if you've heard anything, Bruce. One of the questions we've been hearing about is what companies will basically have chlorpyrifos products available, for this basically 1 year period that they're planning to have it approved for. Have you heard anything about potential limited supply issues or, general availability? I haven't seen anything myself yet either concrete.
Bruce D Potter:Well, I've only know I've only heard of one product that I think is gonna be re has is gonna be available. And what has to happen, Anthony, is those registrants have to reregister, with the state of Minnesota to be, to be allowed to be used on the crop. Even though the compound's legal again, the individual products have to be reregistered, and that's gonna be that's gonna be a slow process. And earlier in the spring, I talked to some people, and and they weren't getting in the supplies that they they requested.
Anthony Hanson:Alright. So we'll see, kinda what comes with the growing season with that one there for some of our insecticides we have available. Bruce, I wanna thank you again for coming here and joining in. We're about the end of our time here. So, any last, thoughts on insect issues coming up here as we get into, 1st part of May heading into June?
Bruce D Potter:Well, I think as, as your crop emerges, as soon as you can get out there and evaluate stands, things for you would, The first thing is gonna be these eel early season, stand reducers. We're getting some getting some calls on white grubs, cutworms, of course, and and wireworms. Those sorts of things are are gonna be your first first problems you have to attack.
Anthony Hanson:Alright. Thanks again, Bruce, and thanks for Debalin for, talking earlier too on the weed side of things. So again, thank you everyone for attending today. This is, University of Minnesota Extension's Strategic Farming Field Notes Program. We want to thank our sponsors Minnesota Soybean Research Promotion Council and the Minnesota Corn Research Promotion Council.
