Timely Crop Scouting as Summer Finally Arrives
Good morning. This is Dave Nicolai with the University of Minnesota. I'd like to welcome you to the third installment of the IPM or Integrated Pest Management podcast in a series here in 2019. We're really encouraged and glad this morning that we have two special guests with us for this podcast, Bruce Potter and Kurt Burns. And I'm going to let these gentlemen introduce themselves.
Dave Nicolai:They're both key in terms of agriculture agriculture and crop production in Minnesota. Bruce, you wanna go first?
Bruce Potter:Sure, Bruce Potter, integrated pest management specialist with the University of Minnesota Extension. My office is with Southwest Research and Outreach Center. It's a couple miles west of beautiful downtown Ton, Minnesota.
Kurt Burns:And I am Kurt Burns. I am an independent crop consultant serving Sibley, McLeod, Renville, Nicollet, Meeker Counties. I also farm.
Dave Nicolai:So Kurt, how long have you been an independent crop consultant in the area?
Kurt Burns:This is my twenty eighth year. So a few years of experience now and I still learn every day.
Dave Nicolai:And I think, Bruce, how long have you been out on the scene in Minnesota agriculture with Integrated Pest Management?
Bruce Potter:That Lamberton in the current position, twenty two years.
Dave Nicolai:Well, it's coming up to the July 1 here, this coming week. There's a lot of things happening out in crop production in the field. Finally, things are warming up. It's been pretty cold and pretty wet, but with the recent warm temperatures over the weekend, we're getting a lot of crop growth, but certainly it's a situation where growers, consultants, ag professionals have to really begin their scouting program in earnest if they haven't already. So let's start off with that, Bruce, and you want to talk a little bit about what's been going on in the fields and what people should be looking at here for the upcoming month of July.
Bruce Potter:Well, think I'm going to turn it over to Kurt first, because he spends a lot more time in fields than I do. When we talk about pest management, whether that's weeds, insects, or diseases, I think we always need to start at the start. Kurt, you and I have talked in the past a little bit about this tough spring and the wet weather, kind of some of the things that that's impacted as far as crop production and management later on this summer.
Kurt Burns:That's right, Bruce. And we've had this conversation this spring and many springs, but it looks to me that tile drainage is the most important management thing that needs to happen on a person's farm today with the type of weather patterns that we're having these wetter springs, these wetter summers, and it's all about timing with IPM. It's timing of getting the field planted on time. It's timing to get the spraying done on time to get the treatments of insecticides or whatever it needs to be. And right now we're facing the same issue.
Kurt Burns:I've got dry beans that need to be sprayed right now because of rotational restrictions with herbicides and some guys can't get in the field because the fields are too wet yet. And so it really comes down to tile drainage of trying to be ahead of the game when it comes to integrated pest management.
Bruce Potter:Yeah, and I think one of the things that's really struck me this spring is that we're seeing a lot of, because of this unevenness and how fields are getting planned, we've got some fields go in early, some fields go in late. We've got big discrepancies in crop stages out there and that's having some impact on insect pressure. Seen some issues with black cutworm. We still have a few of those out there. One of the things we're seeing this year is in soybeans.
Bruce Potter:They're attacking some soybeans. Fields where they're having pressure is a lot of times areas where it drowned out. Last year in corn, typically we think of black cutworms following soybean residue. But there's ways you can attract them into corn residue as well. Seeing some cases with thistle caterpillar, for example, where some soybean fields got in real early and ahead of everybody else, and those are the ones the butterflies were attracted to.
Bruce Potter:They laid their eggs and we've got some concentrations there. I think we're going to see issues. We can talk about this a little later, but corn borer, when we start scouting corn borer, there's going to be some fields that are definitely more attractive and less attractive to those moths as well. So, I think that's a really important aspect as far as if you get good field conditions, you got a good start to the crop, those fields in those areas are off to a good start and even.
Kurt Burns:When I look at too, the disease pressures, you look at Phytophthora, Rhizoctonia root rot, Pythium, all of them in soybeans. And if you have a well drained farm, you don't have those issues that you're dealing with as much. Not to say that there's not out there, but not as prevalent when you have well drained farms out there that the root system can handle it, the water gets drained through the system and you're not sitting in saturated soils all the time. Same thing. And I know a little bit soil fertility here, but same thing with nitrogen management.
Kurt Burns:The well drained farms have much better looking green color corn than the ones that are that have the water's been sitting and having some saturated soils right now with some pan caking of those roots right now that can't get to that nitrogen.
Bruce Potter:Yeah, I noticed that as I drove north here this morning that we're definitely seeing some water and probably some nutrient stress on some of these cornfields. And I think we're gonna see more IDC this year as well just because of that excess water.
Kurt Burns:Yeah, agree with that. I've seen that too now in the last week
Bruce Potter:or so. What about corn? Are there other issues you're seeing in corn, Curt?
Kurt Burns:Well, right now, weed control, there been some issues and again, with the ponding of water we've had over the last few years, some drowned out areas, the water hemp has been an issue. It's the we've had these areas that haven't been able to been controlled because there hasn't been any crop canopy there for a few years. And so a week to ten days ago when guys were treating their cornfields, the temperatures were in them 72 to 75 degrees, some very cool mornings, I could see my breath out there getting out to 05:30 in the morning, it was 4,548 degrees. And I think we had some weed control issues with waterhemp that would now we've had to come back and retreat and some of these cornfields. Obviously, the height of corn has been a challenge.
Kurt Burns:So products are getting limited on what we can use. Coverage has also been an issue. But I think that that got coming down to using a pre herbicide needs to happen in corn and in soybeans because you need to take that pressure off those areas. Because you get a one to two inch water hemp out there and they canopy each other in these patches and you just can't get good coverage out there.
Bruce Potter:Yeah, I'm hearing the same thing. And I think if we can get some of these fields under control a little bit better with good weed management, I think we're gonna have a little more flexibility in how we handle it. We're not gonna be under such stress all the time and trying to stop train wrecks after they've happened.
Kurt Burns:That's exactly right. And right now we had a windstorm obviously come through yesterday with that front that came through. And right now there was products that were sprayed that were kind of off label for the conditions we had and Nick Green snapped a couple of farms I looked at yesterday because a dicamba product was used. And the labels need to be looked at the temperature, the weather forecasting needs to be looked at before we apply these products when we're pushing the height of corn that we are right now.
Bruce Potter:Well, Curt, do you have a lot of your growers or customers or yourself that has cut back on the BT in corn this Yeah,
Kurt Burns:I have been a lot. I would say right now my customer base has probably got there's probably at least 20% conventional corn out there right now in my area and maybe more, maybe more that I don't even know of. But at this point, I have a lot of growers going to conventional corn.
Bruce Potter:Well, it's kind of I think that's not a bad decision for the most part, but it's stuff we're gonna have to pay attention to. We're seeing low corn bore numbers. We still are having a few show up in this first generation flight at Lamberton, but the numbers are low. They're kinda low statewide. But we get back to this uneven planning scenario, and we've got some fields that are gonna be very, very attractive.
Bruce Potter:And, you know, I think you know this, but when you got bigger cornfields that have no BT in them, those are the ones you're gonna focus on. And hopefully that gives you a little indication of how bad that corn bore problem's gonna be.
Kurt Burns:And I think you're right, Bruce. I think we've come complacent because of the BT genetics we've had for a long time now. I think the last I you know, I've been intensively starting to scout more than conventional hybrids, but, you know, twenty years ago, that's when the BT genetics came into play, basically. And it's taken, we gotta get back into that mindset of starting to do a thorough scouting of these conventional hybrids.
Bruce Potter:And I think even we're gonna have to pay attention to some of the BT fields. We haven't seen this issue here, but I know in Eastern Canada they've had some problems where they've got corn borer population. It's a different biotype than we have here, but corn borer populations that are getting around the Herculex trait, BT trait. So, you know, that's just what happens when you go to the well too many times and if an insect doesn't go extinct, we're gonna select for the ones that can survive.
Dave Nicolai:Well, Bruce, was just gonna ask quick ask question here in terms of that. So if a farmer does scout or a consultant does scout, how do they know when they really have a problem or an issue if they're in a non BT situation like we're talking about and what management would they do this year and what management should they think about next year if these numbers are going higher?
Bruce Potter:Well, for corn borer, the good news is this first generation is pretty easy to scout for. You're going look for the tallest corn in the fields in the area, and you're going to go look through and that shot hole damage is going to be pretty visible up in the world. You can look at the economic threshold for those and they're in that world stage corn, they're fairly easy to control with an insecticide. If we start seeing more corn borers and we do a corn borer survey every fall and you know people like Kurt have clue us into fields that don't have BT so we can get a little better handle on what those populations are. We try to keep a handle on if those populations are static or if they're going up or down.
Dave Nicolai:And as I mentioned before, we're coming up to July 1 here, Bruce. So at this point in time from an IPM standpoint, what are some of the insect situations here in Minnesota that growers and others should keep an eye on for and scout for at this point?
Bruce Potter:Well, one thing I think we need to really pay attention to, we have caught some big numbers in some of the light traps. Not that it's a guaranteed problem, but certainly people should be paying attention to true armyworms, both in small grains and in corn. You know, if you've got corn that we talked about weed control earlier, if you've got some corn that had grassy weeds in it early that were fairly thick or you've got some heavy grasses that are lodging on the end of the field, those are edge of the field. Those are places to start checking any place your small grains are lodged or are exceptionally dense. I think next couple weeks, we're gonna see how how that insect plays out.
Bruce Potter:After the July 4, I think we also also, people should be out starting to pay attention to soybean aphids. Most people know there's certain fields tend to have aphid pressure earlier and try to get a perspective on how those early season populations are doing. And one thing that we're seeing this year, we had a problem in 2017, but this spring, the first generation of thistle caterpillars were fairly heavy in some of these early planted fields. They concentrated the butterflies and larvae and damage. But I think we're going to have to watch that later on in July for pressure on soybeans later on.
Dave Nicolai:Do you want to just quickly mention the economic threshold here we're using in Minnesota on soybean aphids?
Bruce Potter:Oh, sure. We can't seem to be able to change it because it's fairly robust and simple, but it's basically two fifty aphid per plant average. We want most of those plants to have aphid on it. You know, 80% or more of the plants with aphids. And we're going to run that all the way through our five stage soybeans up till our six.
Bruce Potter:And as far as protecting yield, it works fairly well.
Dave Nicolai:We were talking a little bit before we started the podcast about potato leaf hoppers. So both of you obviously have had a lot of experience on that. I know in terms of that, you want to set the stage here, Bruce, then Kurt can mention a little bit about what he's seen in the area as well.
Bruce Potter:Yeah, lot of our insect problems, you know, the painted ladies, the black hot worms, army worms, and potato leafhoppers, they're all migrants. They don't survive the winter here. Potato leafhoppers are pretty darn active and particularly on some of these legume crops they can cause a lot of damage. The other problem is the adults are very mobile, so if you cut an alfalfa field they'll maybe move over to soybeans or dry beans. As they reproduce and those populations get thicker there, the alfalfa starts to grow back, they'll move back and forth.
Bruce Potter:It's kinda chasing your tail for a little bit. And Curt, I think you've seen some issues on dry beans
Dave Nicolai:and Oh, alfalfa I've
Kurt Burns:been scouting dry beans now three days before you won't see hardly anything out there and all of a sudden you'll come back three days later and you'll start seeing the damage on the on the first trifoliates right away and so they are coming in like gangbusters right now and second crop cutting of alfalfa is happening road ditch hay is being cut. And so they're going to move into the dry bean areas. And I got a quite a few dry bean acres in the Renville Sibley McLeod County areas, Chippewa, Candia County. So definitely guys need to be out there treating and you're probably going to have to contreat for a couple applications because like Bruce said, they're going to be moving back and forth a lot.
Bruce Potter:Yeah, I think Kurt, thing people should keep in mind if they're retreating fields, you really don't want to go back to the same insecticide more than once. You want to switch those up a little bit. You don't know what they were treated with maybe before, but it's just kind of a good standard practice to rotate your insect icides just like you do herbicides.
Kurt Burns:Just like that's exactly right. Great point on that. Second cutting alfalfa gets cut, gets made up, five to seven days later they need to be in there treating that alfalfa with an insecticide Because they really are gangbusters right now.
Bruce Potter:You are scouting those and looking at number of leaf hoppers per sweep
Kurt Burns:as
Bruce Potter:That is a correct,
Dave Nicolai:yes. So what is the threshold with the sweep net?
Bruce Potter:Well, for alfalfa, it's based on alfalfa height and basically it works out to a tenth of a leaf hopper per sweep per inch of alfalfa growth. It's the early shorter regrowth that takes a pounding with less leaf hoppers.
Dave Nicolai:Well, wanted to talk about a couple other things and we can move back into some of the IPM. But I know the other things that we were mentioning earlier, Curt, were the fertility. And this is a wet year, obviously. So any comments a little bit about some of the things that you've seen just in scouting and in terms of crop health?
Kurt Burns:I think something that came upon the last couple of weeks was when you went from that early corn growth stage to, you know, when we started to go into that V four V five stage, we've gotten through that yellow kind of stage of corn and, and my observations were that any fall manure fall on hydrants and there wasn't a lot of fallen hydrants applied because the type of fall we had last fall. But those acres seem to come around a little slower than what the spring urea spring 28%. I think a couple of things there. I don't think that the ammonium transformed the nitrate quick enough because of the cold soil temperatures we had, plus that whatever whatever and we had there on top move down a little bit further into profile and the roots weren't there yet. So the fallen hydrous fields and the manure fields now have come around, they look good.
Kurt Burns:But definitely there was about a week to ten day window in there where they were not looking as good as the spring applications. Did we hurt yield? No, that was all before V eight stage. It all greened up now by V eight and I think we're all going to be okay with those farms.
Dave Nicolai:The temperatures are going to make a difference here as we go forward. You know, that we always talk about the rainfall and the potential impact it has on soybean production, particularly, you know, we always say, you know, rain in in August in a timely manner, you know, helps to make the soybean crop in a lot of Minnesota. So we've got a lot of season yet to come. But that keeping in mind, you know, I was talking to some coworkers this morning up in the Stearns County area and so forth. A lot of variability, prevent planting and and so forth, and we've got a couple minutes here.
Dave Nicolai:Any any comments about prevent planting that either one of you have in in terms of what what to watch for or or manage? And there's gonna be difficulty, obviously, of figuring out what the what the plant in those areas and so forth, but, there's a concern in a in a conundrum of, you know, leaving these areas fallow, etcetera. But, comments on that, Kurt, anything that you run into?
Kurt Burns:Well, definitely we need to because of NRCS laws, that impact the ground, we definitely need to have a cover crop out there. And also we don't want the fallow syndrome to happen for next year's corn crop out there. But definitely, I think we're gonna have to keep on top of the insect issue because I think this like Bruce was saying this, this whole impact of different crops stages of planting and different sizes of things are going to impact I was in a field of corn yesterday that was bordered three sides of CRP and the stock bore and the in the in the army worm were in that in that first row. I mean, you could see it right off and it's coming from the grass. So PP acres are going to generally probably be planted to a late planted oat crop or something like that.
Kurt Burns:So this insect issue is going to continue on for the because there's so many different planting dates and crops out there they're going to be right now.
Dave Nicolai:One thing we haven't talked very much about Bruce, and that's disease. Is there some scouting things that people need to keep in mind? I mean, we've had a challenging year from a disease standpoint in our field crops.
Bruce Potter:Sure, just want to touch on one thing with the prevent plant stuff. I think people can't ignore the weed control aspect of that. Some darn big weeds out there and especially things like lambs quarters are right on the edge of form and seed. So we don't want to make things worse for next year. As far as disease, yeah, wet conditions, you know, you always tend to have a little more disease.
Bruce Potter:You know, some guys are using fungicides on corn and soybeans, but really it's probably to their economic advantage to do some scouting and make sure they actually have some diseases in there worth treating. The other thing that mentioning disease, and it goes back to an insect issue, we've got a new soybean insect in Minnesota and the Upper Midwest called the soybean gall midge. That injury mimics some of the soybean diseases. If you see plants dying and wilting on the edge of the field, it might be worth your while to take a look at those lower stems, see if you've got discoloration. If you do, peel some of that epidermis back and make sure there's not an insect larvae in there versus some sort of pathogen.
Dave Nicolai:If they want to learn more about some of those things, I think you've written some articles on soybean gall midge. Where can they go to read out a little bit more about that and you have some traps and some monitoring going on?
Bruce Potter:In Minnesota, they can go to the Minnesota Crop News website and we've got a couple of articles on soybean gall midge. Heard an extensive check off funded effort between Iowa, South Dakota, Nebraska and Minnesota trying to get a handle on this new insect. We don't know much about it. We don't know how chemical control works, that sort of thing. But we'll keep people posted during the season.
Dave Nicolai:At this point, Kurt, are there any other items that you would like to cover a little bit about what growers should be thinking about doing or maybe not doing? Well In the month of July coming up here.
Kurt Burns:The biggest thing I am discussing with my growers right now is that we are a long ways from canopy in these soybean fields. And Bruce mentioned it about weed control and the PP acres. Well, it's about waterhemp control before it emerges. And I'm really proponent of layering these pre emergence herbicides. And so if you're in 30 inches rows, or even 20 inches rows, got a long way to go to before canopy in these soybeans with late planted soybeans and a cooler spring.
Kurt Burns:So I'm encouraging growers to spend the extra $10 an acre and put another layer of herbicides out there, especially if they can get out in these fields before rain and get that herbicide activated, then it's just going to help you down the line for waterhemp because waterhemp loves light and it's going to come through the light and we got a long way to go for canopy.
Dave Nicolai:And our canopy is going to be less and less this year given everything else that we do in terms of planting. I know Doctor. Jeff Gonzalez has always said, you know, that rule of thumb, that four inch, and I know Bruce has seen this too with lambsquarters, it doesn't take too long and things get up and if it gets dry, things get hardened off. So really scouting for that post emergence and the waterhemp biology. Waterhemp keeps emerging all all season long.
Dave Nicolai:It'll it'll come up very small and set seed, you know, the corn. We've all seen that. So, you know, those are really two important weeds with that. Bruce, any other last comments on things that people should be doing or thinking about doing, or as we mentioned before, maybe not doing, but certainly being proactive out in the field?
Bruce Potter:Well, thing people really need to keep in mind is that not every field has the same insect, weed, or disease problems, and they're all unique, and the only way you're going to understand how to maximize your economic return on your management is by scouting. So get out there, look at those fields, or have somebody like Kurt look for you, particularly if you're old like me and can hardly see aphids anymore.
Dave Nicolai:Well, appreciate your advice, sage advice for both of you. You had many, many years in the field. We'd like to wrap up this podcast. We'll be continuing with others in the future here with other University of Minnesota staff and consultants, etc. So this is the third installment of the Integrated Pest Management, and we'd like to thank again Kurt Burns, the independent crop consultant from the McLeod area, Stuart area, and also Bruce Potter from our IPM staff at the University of Minnesota at Lamberton.
Dave Nicolai:So with that, thank you again, we look forward to visiting more about these items in the future.
