Tips for Forage and Pasture Management: Insect Pests, Production and Harvesting
Well, good morning, and welcome. My name is Dave Nicolai. I'm with University of Minnesota Extension Educator in Field Crops, and I will be your host this morning for today's program on, University of Minnesota strategic farming field notes. Before we get started today, just a couple of, items that I'd like to go over real quickly with, with the folks that are viewing. We have an, answer and question situation here, so we have an opportunity for you to ask questions with that.
David Nicolai:There is a q and a box at the bottom of your screen. If you'd like to enter questions, use that. There's also a box at the bottom of your screen for, chat box that will reserve that for technical issues. All you have to do is hover your mouse near the bottom to see that toolbar options including, the q and a box. When we conclude the program today, when you log off, there'll be an opportunity for taking a three question survey that'll help us a little bit in terms of, program, situations and program discussion, for future sessions with that.
David Nicolai:This session is being recorded. It'll be posted on your favorite streaming services later, on this week, and we'll have an opportunity for that as a as a podcast as as well, with that. Again, welcome to today's strategic farming field notes. These sessions are brought you by the University of Minnesota Extension with general support from farm families throughout Minnesota. Also, the Minnesota Soybean Research and Promotion Council, and another sponsor is the Minnesota Corn Research and Promotion Council.
David Nicolai:We're happy that you joined us today for today's section in all things forage management. With this, we have a couple of guest speakers that are experts in their field from different parts of the state of Minnesota. We have Anthony Hanson, who is an extension educator on a regional basis, primarily dealing with integrated pest management. And Anthony will be talking a little bit about forage pests, the forage crop and those situations. Also, have a very special guest, Troy Sulzer.
David Nicolai:Troy Sulzer is an extension educator. He is actually located in parts of Northern Minnesota. He lives in the Carrollton County area, covers a lot of St. Louis County and in the agriculture situation. And Troy will be talking a little bit about forage management, for livestock, forage management in terms of, feed supply, and also, we'll segue into pastures as well, with that.
David Nicolai:So with that situation, I'm gonna turn it over to Anthony. And, Anthony, we've we've had a kind of a more, I guess, a lack of snow cover, so to speak, in in terms of our forages. How did the alfalfa survive with that? We've had some really warm temperatures. We've had some rain, quite a bit of rain recently.
David Nicolai:How's the alfalfa crop looking in terms of of stand and how did it manage through this past winter and what's it look like going through into this coming season? So just a couple of comments in general.
Speaker 2:Yeah. So kinda talk about the agronomy side of things a little bit before we jump into the pests. And if you think back to last winter, you know, we had a lot of areas that really didn't have snow cover at times of the year, and that also timed up right when we had our coldest spells, it seemed like. So for some areas of state, especially, you know, we did see some winter kill, especially some of the older stands. So there's there's some fields that are we're looking a little rough this spring there.
Speaker 2:Some some are starting to shape up a little bit, but this is kind of a point where, you know, folks should definitely be considering, you know, what am I gonna do next year especially, or do you need to supplement at all with anything getting into that field now just in case, you know, you're not getting enough stand out there for your alfalfa. But the key thing for kind of that winter question a little bit on the pest side of things is that perennial question we've had about alfalfa weevil. And that one too, you know, whenever alfalfa doesn't do well in terms of winter, usually alfalfa weevil doesn't do as well either. So when we look at some of our, you know, kind of really rough models we have for alfalfa weevil overwintering mortality, It does look like in some areas of state, especially here in Morris, we had some pockets that we should have seen really heavy alfalfa weevil mortality. So that's the hope.
Speaker 2:Numbers might be lower this year, but I caution about that because there's gonna be pockets where maybe someone had some snow, maybe they had a lot of ground cover that would keep that temperature quite a bit higher. So you think about this year, we had a lot of frost deep into the ground that helped us out on the pest side a little bit. But, yeah, if you're in a protected area, chances are you might still have some alfalfa weevil out there. And kinda what I've seen across the area, at least so far this year, alfalfa weevil numbers have been pretty low in the fields here, at least in West Central Minnesota. Round Morris here, the highest count I had in one field was just three alfalfa weevils for 30 plants out there, and that's pretty low still.
Speaker 2:I'm kinda expecting to see more if, at least in terms of what we'd see year to year. But so far, at least in this little area I've been looking, it's been pretty low numbers. So I'm gonna say a little lower risk here so far, but the next week or two is really what I'm I wanna keep an eye on because they could still show up in numbers.
David Nicolai:Well, I think one of the reasons why we should explain we're talking about this last year, for the first year in many years, it was a very serious problem across the state of Minnesota of off we will cause quite a bit of damage, quite a bit of of crop loss and and stand loss. So people are very sensitive to this. I know in Eastern Minnesota here that we we had several fields that were devastated with it. You wanna explain a little bit about the life cycle here, in terms of what happens over winter? Are we, quote, you know, out of the woods, so to speak, with this?
David Nicolai:Is it just a first crop, situation and it doesn't, really present itself of a problem? But talk a little bit about the life cycle here.
Speaker 2:Yeah. And in short, we're not out the woods yet. But, yeah, if you backtrack a little bit, I mentioned those alfalfa weevil overwintering. Those are adults. So they'll lay eggs basically in the stem of the plant come spring.
Speaker 2:So they were doing that early early May, maybe even April with the warm weather we had. But all of those larvae that hatch from those eggs, those hatched out roughly a week or two ago, and they'll be feeding on the leaves. They skeletonize them, so you'll see kind of a almost a windowpane appearance or it'll kinda be either brown or kind of a white look on the tips as you look across a heavily infested field. So what's happening right now is those larvae are going through a few different molts. So they have four different instars we call them.
Speaker 2:And when we look at some of the forecasts we have with degree day models, they're about their second or third instar across Southern Minnesota right now. So they're about halfway to finishing development. When those larvae get to their fourth instar, the next stage is, you know, pupa or kinda like think of butterflies. They have that chrysalis stage or cocoon, similar setup there. So once they go through that, they turn into adults eventually.
Speaker 2:And those adults, they aren't laying eggs. They're really not eating or causing damage to the rest of the year. So we have this window just looking for those larvae. And when I look at some of the degree day forecast right now, it's, you know, kind of across Southern Minnesota, like I mentioned. If I look ahead about a week, they should be hitting that pupil stage at least across South Central Minnesota up along the Minnesota River Valley as we head west.
Speaker 2:But there are some complications with that too with these predictions. So I don't wanna say just wait a week and you're good for that part of the state. But I would say definitely at least the next two weeks, I wanna be keeping an eye out for especially a lot of feeding damage here. Hopefully, it will start to tail off in terms of risk in about the next week or two.
David Nicolai:Do you wanna mention about from integrated pest management specialist, how should a grower or ag professional go out and scout and what are the threshold levels here?
Speaker 2:Yeah. So there's a few ways to scout for this one. You know, some people like to use the sweet net and that's alright for just seeing if it's in the field. It may not be the most accurate, though. So what I like to do is I just carry a five gallon bucket around with me in the back of my truck.
Speaker 2:You're grabbing 30 plants across the field, so just grab 30 stems, spread that out across the field a little bit. And what you're gonna do is just hit those plants in your bucket. That's gonna dislodge. Hopefully, all or most of the alfalfa weevil in there, and then you get a pretty good count just based on what's in the bucket there. So hopefully, you're not losing them to wind or other things like you might be with a sweet nut, but I tend to use both out there.
Speaker 2:But if you really want a good count, keep a bucket along that will let you get a quick estimate there. And if people wanna know what the thresholds are, I generally send them online to some of these other resources we have. So people look up Minnesota Crop News and alfalfa weevil or just through U of M extension, they'll see this whole table set up showing what the different thresholds are. It's all based on plant height, your crop price as well if you're factoring that in. And, you know, it could be anywhere from just one larva per plant all the way up to three or four across that whole spread there.
Speaker 2:So some of these plants can tolerate quite a few larvae out there. So that's one where I'd just say check for your specific situation. It gets pretty complicated for these thresholds compared to something like soybean aphids where we just say 250 aphids per plant. And then that's your trigger point.
David Nicolai:Well, if you're getting more than five larvae per plant, you really need to be looking very much closely at some of those standards because you're at the high side, I would imagine.
Speaker 2:Yeah. One thing to think about too is, you know, a lot of folks I saw a lot of hay down this weekend here. There's still some being cut at least in this part portion of the state, but this might be helping us out a little bit because if you are mowing early, that tends to cause some weevil mortality. Well, if they're already low numbers and if they're a little less mature, they may not survive as well too. So, you know, at least as far as I can say right now, the timing might be helping us out.
Speaker 2:But, yeah, I don't know for sure if, you know, we're gonna see a resurgence come up in the next week or two. But, you know, keep an eye out. There's gonna be pockets somewhere, I'm sure. But at least it seems like compared to last year, it seems at least like it's a little lower pressure.
David Nicolai:Should they monitor that second that growth if they made that first cutting? Is there still issues here as the second growth is coming?
Speaker 2:Yeah. So you want to be monitoring that regrowth because you can get some weevils basically concentrated in that windrow, especially. So if it takes a while to get that, you know, raked or bailed up or whatever setup you have, they might be feeding under that, especially if they're not exposed to the sun. They do pretty well in those situations. So what we can do is you just kinda look at, you know, a one foot square grid.
Speaker 2:You can toss it out a couple of spots in the field or especially look under where the wind rose were. And we can do some ground scouting. Usually, it's, you know, lower numbers a little bit. Again, we have some guides folks can look up for that based on if you have sandy ground or a little closer to the clay end of things. So that can vary quite a bit too.
Speaker 2:But overall, that's one where it's usually shorter window. And then you're back to scouting the actual plant material there at least. So it won't be too long. You have to be on your hands and knees looking for larvae on the ground. I know a lot of folks don't wanna spend too long doing that there, but, you know, that's at least one angle they can look at for a little bit to kinda get through that period right after cutting.
David Nicolai:I might mention for those of you that are watching this morning, we put in our a link into the chat for alfalfa weevil management. New crop news, I believe, from 2023, Anthony. So, there's, quite a bit more information. Anything else in terms of other, forage management, pests, aphids, etcetera, pea aphids you wanna mention?
Speaker 2:Yes. So so far, like I mentioned, it's been pretty quiet in the alfalfa, but aphids, especially pea aphids, are the ones I've been seeing more than anything right now. Not at numbers I'm concerned about, but they're definitely present a little more than some other years. So just the short, kinda to do list for that one there. If you are seeing closer to a hundred aphids per stem, that's definitely threshold levels.
Speaker 2:That's all again based on growth stage. So roughly if you're around a 10 inch plant, you know, 40 to 50 aphids per stem as you kinda progress through that, you might be 75 aphids per stem, and then a hundred is basically if you're over 20 inches tall for a plant there. So, you know, again, it's gonna be pretty high numbers of aphids there if you are actually hitting thresholds, so we can tolerate quite a few of those. One thing I do wanna mention for pretty much all of our insects, we at least alfalfa, we don't have very many options out there. So folks remember chlorpyrifos, that product has been going through a lot of regulatory changes.
Speaker 2:This year, it is available to use if you have it on hand. Basically, it's an existing stock order. You can use it until the June, so that does overlap with a lot of our alfalfa insects. But anything registered at this point, basically, you won't be able to use it after June, and you had to have it on hand already. Now there may be some other products being registered after June 30 that have updated labels.
Speaker 2:But for now, basically, just let folks know that chlorpyrifos products, you have a limited window to use those for now. And common trade names like Lorisband, that's not available at all. So you might have to look and see what some of these other generic products are out there for that one. But, yeah, a lot of our other products like Steward, that one seems to be working pretty well for alfalfa weevil, and we're still concerned about pyrethroid resistance out there for alfalfa weevil as well. So we're hopefully gonna get a little screening done this year to see if that, pyrethroid resistance is in Minnesota and formalize that.
Speaker 2:So if anyone has a problem field, especially that it looked like a pyrethroid failure, I'd be interested to hear about it and maybe we can get some samples out of there.
David Nicolai:Well, before we go to Troy, just one last insect I've you wanna mention a little bit on, and we don't have it quite yet, but potato leafhopper is a situation if we turn, dry in situations with that and stress the crop. You just wanna mention a little bit about leaf potato leafhopper and any economic thresholds, that's theoretically yet to come.
Speaker 2:Yeah. So potato leafhopper, usually later season pests, their populations have to build throughout the season. They've migrated up from the Gulf Of Mexico every year. And in that case, that's one where, you know, I'm not too worried about it right now unless you just planted alfalfa this year. It's that first planting the first year planting that that tends to be a little higher risk there.
Speaker 2:So that's one where you see kind of stunting on the plants that kind of v shape a little bit. Also keep in mind for your thresholds, if you do have any kind of resistant varieties out there, they can tolerate quite a bit more in terms of potato leaf hopper. So that's one where, you know, it's, you know, pretty manageable at least with that one. So it's good to say, yeah, just keep an eye out for that. In terms of thresholds, there's, again, a few different ways to do that.
Speaker 2:But if you're just doing a sweep net setup, if your plant is, you know, taller than 12 inches and you're getting more than two potato leaf hoppers per sweep, that can be your you got a quick threshold you could use there at least there.
David Nicolai:Okay. Great. Great. Well, Troy, you get to travel, quite a bit of over over the state and you talk to growers. I know I know not just in, obviously, Northern Minnesota, but in Southern And Central Minnesota.
David Nicolai:What's your sense of how the, alfalfa survived, the winter, this year? Of course, it's it's a difference in in snow cover, but, did things come through pretty well in in in terms of tolerating that from a winter injury or winter damage?
Speaker 3:Well, in our particular case, Dave, Anthony, did a nice job framing, the components of, this winter. And generally speaking, I would say, in the northern portion of, Minnesota, certain areas had received plenty of snow, and, they really didn't see much, damage. But what I would consider the southern portion of the area that I really work in didn't receive any snow virtually the entire winter. And so it the old East Central part now has become the, probably, 50 to 80 miles further north. At least that's what it looked like this winter in regards to snow cover.
Speaker 3:And those particular areas, the older stands did take it quite hard and really are something that we need to address this season, especially to address some of the reduced yields because of that.
David Nicolai:Speaking of that, if you if you were to go out and look at an older stand, do you have any rules of thumb of, not just stems or plants per square foot when you are really concerned like it's, well, this is about time to go. We need to do something else here.
Speaker 3:Yeah. So in relationship to that, I always look at, the open area, the position of, the plant species that are out there. And, you know, many of, the growers I work with utilize a combination of not only alfalfa, but grasses, mixed in with, their forage. And some of them are spreaders, where they actually, spread out and fill in those areas. We don't necessarily want to count on that, and others are bunch grasses.
Speaker 3:And so knowing that, for example, orchard grass is a bunch grass, would really help you in making some of those decisions in relationship to, Are you gonna harvest your first crop and then plow that down and put corn or sorghum Sudan or something like that in as an alternative feed source just because, both the quality perhaps is down, but also the yields are down dramatically.
David Nicolai:So over the years, you've seen people use different grasses and so forth of alfalfa. You mentioned orchard grass. What are what are your top couple of grasses that you felt have the longevity and the and the nutrient value or nutritional value?
Speaker 3:Well, orchard grass is one of those grasses that have very high productivity, but tends to mature a little bit earlier, than many of our, alfalfa varieties that we have. And so, if we're looking for a higher quality, maybe a metal fescue or a metal brome would match up a lot better in relationship to, timing on cutting. And there is absolutely a huge benefit to, adding, for example, metal fescue to that mix for the quality, specifically in relationship to the digestibility of the fiber fraction of that plant as compared to alfalfa. And that combination, of high quality grass, along with alfalfa really offers, the producer a lot of benefits in regards to, the composition of how that would feed to the livestock as well.
David Nicolai:Let's, maybe segue a little bit into folks that may not be harvesting but may have pasture situations. Talk to us a little bit about how those pastures came out over winter and, what, what types of of forages have been working well if you're going to either, you know, do something with a new pasture or rejuvenate maybe an existing stand a little bit on that, but if your intent was primarily to use it as a pasture situation.
Speaker 3:Well, this particular season, the pastures have been very slow to come out, especially in Northeastern Minnesota. Other parts of the state now that they've received rain, have begun to, kick in, especially on those lighter soils. The thing to remember about grasses is that they respond very directly in relationship to nitrogen, and they respond to the amount of moisture that is out there. And so with the lack of moisture this spring so far, the grasses have really not taken off very well, up to this point. There is some, hope in much of the state has received a pretty substantial amount of rain, and that will kick things in.
Speaker 3:For those of you that maybe haven't, some timely application of nitrogen, might be a really good place to start, especially based on last year with, extremely heavy rainfalls. Losing that nitrogen early, did have an impact. So, go out there, spend some time not only in your fields, but also out in your pastures evaluating where things are at. They they have the same signs. Nitrogen deficiency is, that pale light green color.
Speaker 3:Look around and and look at how you can do that. You also mentioned the components of potentially doing some renovation. Part of that is driven by the the lack of competition that you the species that you really want to have in your mix. If those species aren't aggressive and actively growing, that allows for things like weeds to come in and, take advantage of that situation. And so the more competition that we can provide through healthy plants being out there, it'll minimize the, the weed pressure.
Speaker 3:With that in mind, fertilizing is is one really good option consistently, and allowing that plant to be managed well in relationship to harvesting that just like you would with field, with rotational grazing, taking those animals out of there, and letting those plants regrow. If, if you have a situation with, with, your pastures, maybe needing some attention in regards to that, utilizing a process of no till seeding, zip seeding, as some people call it, where we actually go in, perhaps, use, glyphosate to to spray out all of those those weeds and grass and then introduce the species that you would like to have growing will help dramatically in regards to the productivity. If you do that, realize that those plants need to get established, develop that root system, so you may have to delay your harvesting. And so adding a nurse crop with that, perhaps oats or something like that, might be a way in which to get some feed off of there, very lightly grazing that, and then removing the livestock so that opens that up. That nurse crop is help helping to protect those seedlings, get them off to a good start, and then, remove that, potential shading.
Speaker 3:That is good feed. The livestock do, like, consuming that. And, and then once you do that, allowing those plants to continue to establish, and it'll help you, into the future.
David Nicolai:Is there a better time for renovation here going forward if you're if you're stand is is so I obviously, we can, you know, we can apply fertilizer, especially in a lot of Central And Northern Minnesota when you would, wanna do the renovation?
Speaker 3:Well, there is still time, in, those portions, Dave. It really does depend on the season. Again, those plants, as all seedlings, they are very small seeds. So it requires, those plants to, take advantage of nutrients very quickly from the soil after it has been, after the plant has germinated or the seed had germinated. And so if, there isn't adequate moisture, you have that risk of them establishing, but then actually, drying out and burning off.
Speaker 3:And so fall is a great time to consider, doing that, for a couple reasons. If you, spray at that point, your kill on those perennial weeds is, usually much more successful, and so that is a benefit from that perspective. And additionally, by that time, there's not much many of these pastures are pretty much run out, and so taking them out of production, and allowing those plants to establish, from, you know, maybe the mid August time frame, is a good time to get that done so that those plants have a nice fall to get going and, establish well.
David Nicolai:You know, Anthony, you're located more into the Morris and Starbuck area and have some interest in terms of cattle on on yours and your family situation with that. Any any questions or comments you might make, in terms of management and pastures otherwise and observations that you have on forages?
Speaker 2:Yeah. Some of our pastures the last few years, we've been dealing with the drought, especially on the hills and white grubs are really thick in some of those areas. So we're still seeing the pastures recovering from that. It's still looking pretty weedy. So when we're talking about rejuvenating pastures, there's definitely some spots, you know, across the state that are like that.
Speaker 2:But Troy, I kinda had a related question for you. This is actually something we're doing on our farm, I'm sure it might apply to other folks here too, but we're planning some dry land alfalfa just to try to get a little more forage acreage in. And, you know, that's a little different setup for us. In this neck of
David Nicolai:the woods, we have a
Speaker 2:lot of irrigation. So I guess any just quick thoughts on, you know, dry land forages, but especially alfalfa and kind of the field crop situation, things to keep an eye out for. You know, the rain helped us out a bit, I'm sure, here, but kinda what you might look for the rest of the year on that?
Speaker 3:With dry land alfalfa, there's a few different things that I would keep in mind. The benefit of alfalfa, it is generally a deep tap rooted plant and really can harvest moisture from a very significant, soil profile. And so that is really beneficial, when thinking about that. And there's so many other reasons that, alfalfa is beneficial in a rotation from the nitrogen fixation, what have you. One thing that I really have learned over the years in relationship to that management is if that plant gets stunted during that growth period, maybe it's drought, maybe it's insect damage, in in most cases, it almost requires, or it seems to require an actual harvest to, restimulate that to get it going.
Speaker 3:And so oftentimes, many of my growers will, will say, well, after that drought, I just didn't see the, regrowth anticipated from a two inch rainfall, for example. And what I have learned over time is actually going out there and and harvesting it about that time, after that rainfall is really beneficial to get that plant rejuvenated and and growing in its natural sort of, physiological, activity from that perspective.
David Nicolai:Well, great. Great. We're, approaching the, end of our time slot here. Any last words, Anthony or Troy that we didn't cover, that you wanted to bring up?
Speaker 2:I think we'll just we'll see how, yeah, all the foragers are looking here with that rain that most of us got. I know further north, it wasn't quite as much, but that was a healthy shot right when we needed it. So, hopefully, we're set up for a good season to start here.
David Nicolai:Okay. Troy?
Speaker 3:No. I really appreciate the opportunity to be here and, encourage folks to, think about some of that strategic management, from the perspective of giving your your, pastures, the opportunity to, actually get harvested and regrow.
David Nicolai:Alright. Well, thank you. Thanks again, Anthony and, and Troy. We want also thank our listeners and, folks, for attending this today's program of University of Minnesota Extension field notes. We also wanna thank our sponsors again, the Minnesota Soybean Research and Promotion Council along with the Minnesota Corn Research and Promotion Council.
David Nicolai:When you log off today, they'll please take the quick survey. Again, that'll help us in terms of planning for future, programs. We will be back again next week at this time, and I believe that'll be Wednesday, June 4. We'll have a couple of, different subject matters. Hopefully, we'll we'll be talking about small grain, management a little bit more, disease, and some pest problems and other small grain situations with there along with some, fertility and crop fertilizers.
David Nicolai:We wanna talk a little bit about, supplemental and and how our row crops are doing as well. Well, with that, we wanna wish you also to have a great day, and we will, see you next week. And, thanks both to Troy and Anthony. If you have further questions, I think it was in the chat, you can email them directly, through the the UMN system with it. So thanks for attending both of you, and we appreciate that.
David Nicolai:And we look forward to seeing you all at 08:00 next week on June 4 for the next edition of University of Minnesota Strategic Farming Field Notes. Thanks. We'll talk to you later.
Speaker 2:Thank you. Thanks, Dave.
