Field Crops Webinar Series - Field Crops Webinar - Weed Management - Sprague Hager

February 7, 2022

Video Transcript

- Good evening everybody. First of all I'm really excited that Aaron's here with us tonight. I've known Aaron for a long time. He actually completed his master's degree here at Michigan State and worked with Karen Renner and I think that was when our first paths crossed. I was an undergrad worker in the next program. So it's been and been great to know Aaron this long and actually worked with him when I was down in Illinois for a few years. So it's great to be able to have a good conversation with him today about some of the topics that we're gonna be facing in 2022. What I thought I would do is first start out talking about one of the issues that we know is gonna be an issue coming up this next year. So as we've looked at all the changes that we've seen with the COVID and a lot of other things that have happened over the last couple years, one of the things that's been a challenge is getting certain items and herbicides is one of those items where it looks like it's gonna be potentially a problem for 2022. I know there's been a lot of talk about what are some of those shortages. And I know here we've heard a lot about the potential for glyphosate shortages as well as liberty shortages and I thought I would ask Aaron what his thoughts are and some of the things that he's been hearing about down in Illinois. - Sure. Well, thanks for the introduction, Christy, really appreciate that. We hear in Illinois primarily about concerns with the shortages of glyphosate products, especially (indistinct) glyphosate products, and the glufosinate or liberty type products here as well. And not only are there going to be shortages of those two active ingredients, we've seen some pretty significant price increases here as well. We have a rural farm store here in the Champaign-Urbana area that sells several different brands of, you know, of glyphosate products and I think the price already on those has more than doubled, you know, in the last couple of months. And last time I was in there they had a new little sign up there by all these glyphosate products, I think they're now limiting each purchase to, you know, five gallons or something like that. So most of the other stuff that, you know, we've heard about there could be some shortages of liquid AAtrex products from Syngenta, but a lot of the other premixes that we typically rely fairly heavily on here in Illinois, at least for going into the season, I think, many of our retail applicators are fairly comfortable if they've got those supplies in stock. One other thing they're not sure of is about refills. If they can get anything, you know, if they run out of a particular product or they're gonna be able to get an in season refill on their bulk tanks. - Yeah. I know that's been, you know, one of those things, that's been one of the major questions that I've been getting is, you know, well, what do we do if we don't have these products or if we can't get refills or resprays, what are some of the things that we can do? As well as looking at some of those price increases. But what I thought I would do next is just kind of, you know, show the viewers as well as you some of the top weed challenges that we feel like we'll probably run into in 2022. I know we did kind of a quick survey this last December and asked a number of people that attended our December pavilion meeting and asked them, you know, kind of what some of their top weed challenges for 2021. And looking back at our 2021 data and also 2020, they're pretty similar. And, you know, in Michigan, what comes up, number one, over the last several years has been horseweed and (indistinct) and that's been a huge issue. And one of the things that we've really seen an uptick in is waterhemp problems and I know that you've had a lot of experience with water hemp and we'll talk a lot about some of the challenges that Aaron has worked with down in Illinois, but you can see some of the other ones, lambsquarters, just some of our annual grasses, whether it's Foxdale, the ragweed species, you know, in 2010, we had palmer amaranth move into the state and it's been, you know, potentially a problem, but this last year bubble leaf and then obviously volunteer corn. You know, I'm just curious, do you feel like those are some of the same problems that you guys are dealing with, or you got some additional ones or things that we should be looking out for? - Really, that list that you've got here is very similar to most of our species that are fairly common across the state here in Illinois. Now we've got, you know, roughly around 23 million acres of row crop, but one thing that would be a bit different would be which ones are ranked where, here in Illinois, and by far and away, you know, waterhemp is now our driver species on the majority of our acres. It's one where, you know, our farmers are having to account for it, or they're having to plan for it every growing season. It's really been an interesting species to watch in terms of its distribution and movement around the state. It's actually native to Illinois that it, you know, it's always been here, but you know, up until about maybe a short 30 years ago, most people in Illinois didn't even know what it was. It was primarily confined to the older, more weathered, heavier clay soils in the very Southern part of Illinois. But, you know, over the last 25 years, we can find water hemp now in every one of Illinois's 102 counties. Our horseweed is interesting because, you know, when I first started at Illinois 29 years ago, it was almost exclusively behaving only as a winter annual, but we tend to see more and more spring emergence now. Of course, those can be a bit of an issue, certainly. We still have issues, you know, we're trying to get good control of horseweed. And that did emerge in the fall on our no-till acres, especially our no-till soybean acres. So, you know, you're other ones that you've listed here, lambsquarters, we have, you know, of course that's a challenge every year. We would probably add cocklebur, maybe, to our list that you don't have here. And, you know, volunteer corn. It probably, in Illinois, be quite a bit higher. It was actually last fall after harvest. It looked like we had volunteer corns planted as a cover crop. It was, you know, tremendous populations and fairly confident not all those drop kernels actually germed last fall, so I suspect we're gonna have to contend with volunteer corn again in 2022. - Yeah, you know, that's interesting that you brought up cocklebur. That is one weed that, you know, we've been getting a lot more people asking questions about. So it is showing up in some of our fields. Didn't quite rank up on this list, but I think that's one of those issues we're gonna need to really start thinking about. Are there some things you might wanna bring out about cocklebur that, why you think it's, you know, become more of a problem over the last several years? - That's a really tough question. I know you and I have talked about this before, as well as, you know, some of the other weeds folks across the Midwest and up till about, I don't know, five or six, seven years ago, you really didn't see much velvetleaf, you didn't really see much cocklebur in soybean fields here in Illinois. We have a very effective portfolio of products that are very effective on that weed, actually on both of those weed species. But, you know, for some reason, you know, it's been fairly consistent now in the last five to seven years, we see more and more velvetleaf and cocklebur that are popping up, you know, through the soybean crop. And we've screened a few populations before. I'm sure others in other states have too. We haven't found anything that we would label, you know, glyphosate resistant or anything like that. So we start to, you know, kick around an idea. Well, as you know, we've seen other weed species actually shift in their germination and emergence characteristics over time. I know you worked with giant ragweed at your time in Illinois. And, you know, I think it's pretty clear. The evidence is pretty clear that sometimes these species can shift their emergence timing based on, you know, practices that they've been exposed to for many years. So, you know, I guess there's an outside chance we maybe seeing something similar with velvetleaf and cocklebur. - Yeah, and I think, you know, that's one of those things is those later emerging weeds that seem to be the biggest issue, especially, you know, as you mentioned, kind of that shift in emergence patterns with horseweed, you know, in Michigan here, we've seen that as a huge problem because a lot of times we may not get initial emergence until, you know, really early May, the last part of April. And then it just continues, especially if, you know, if we have any holes in that canopy and that's been a huge issue. And I think as you look at this list, you know, the things like horseweed, waterhemp, palmer amaranth, giant ragweed in particular, those are ones that seem like they come up later in the season and make it a little bit more difficult to control. - I guess I was a little bit surprised to even see giant ragweed on your list. 'Cause, you know, when I was MSU almost 30 years ago, you know, I don't even recall ever seeing much giant ragweed across the state of Michigan. - Yeah, I think it's moved up from Indiana and Ohio. We've got them on kind of those southern tiers of counties as being more of a big issue. And then we've got a few populations that pop up other places, but you know, if you remember correctly, common ragweed's kind of been the driver on a lot of different acreage, and also lambsquarters. The one thing, you know, just to bring up to the audience here, some of these weeds, when we start thinking about, you know, these weed challenges and we talked about the potential for shortage of glyphosate, you know, maybe that doesn't affect many of these weed problems because a lot of these, particularly the horseweed, the waterhemp, and the palmer amaranth, if you were to screen any of our populations in the state, I would say probably over 90% are resistant to glyphosate. And in many cases many of them are gonna be resistant to those ALS inhibitors. And I think you guys probably have that same issue in Illinois, I'm guessing. - Yeah, with our horse weed and, you know, full confession here, I don't want to be misleading anybody, we really have not done, you know, extensive resistance confirmation with horseweed like we have some other species, and, you know, Purdue University, Ohio State University, years ago they really did what I think is an excellent job trying to determine, you know, what's the frequency of glyphosate resistance in their populations? Dr. Steckel of Tennessee did some of the same things. And then when you look at how these resistant plants, you know, what their morphology looks like after being sprayed with glyphosate, it's like, okay, we've got it here too. I mean, our plants that were sprayed that weren't controlled looked exactly like, you know, the resistant ones that Purdue was showing, that Tennessee was showing, that Ohio State. But, you know, our key species right now of course is the water hemp. We here in Illinois have confirmed resistance in waterhemp to herbicides from seven different side of action groups. That's a lot. We actually have one population that we've worked on here within the Champaign-Urbana area that has resistance to herbicides from six different classes in that one field. So, ironically, and I don't know how to explain it, that population that's resistant to herbicides from six classes. however, we can still control it with glyphosate, but we have noticed over probably about the last four seasons, you know, the level of control when we first started on that population maybe seven years ago, eight years ago, I mean, you couldn't miss a plant with glyphosate, but now it's becoming a little bit less sensitive, a little bit more challenging. So, and it'll continue to happen. We have no doubt. - Yeah, you know, I'm kind of excited, as we get a little bit further along, I've got a few slides I'd like to have you really specifically dive a little bit more into some of those populations because it's pretty scary. That's for sure. Having all those resistance problems. The other thing I wanted to mention is, you know, from our ragweed standpoint, we're pretty lucky we don't have what I would consider tons of common ragweed that's resistant to glyphosate, but I would say a majority of it's resistant to some of those ALS inhibitors, you know, that happened fairly quickly. And then that southern tier counties, we do have both glyphosate and ALS resistant giant ragweed. So as we start thinking about some of the potential ways we're gonna manage these weeds, you know, glyphosate's always been a huge part of many weed control programs, but, you know, with some of these driver weeds, it's not necessarily helping with those, but maybe helping with some of the others that are out there. So that might give us some other options to think about for management. So what I thought I would do, Aaron, is ask you a little bit about what do you think some of your recommendations for weed control and corn are gonna be for 2022, especially looking with, you know, some of the limited glyphosate and glufosinate, and potentially, even as you mentioned, atrazine. - You know, it was interesting, Christy, for many many years, you know, the Illinois corn farmers did not plant any what I call naked acres, like what you're showing here on the slide. We had a pre-emergence herbicide under virtually every one of our 11 million corn acres every year. But then when the glyphosate resistant hybrids came into the marketplace, it was interesting because you could drive across any part of Illinois and see people who were trying to do this total post system in corn. Generally speaking, they did that one year because their thought process is, well, you know, as effective as glyphosate is, I can let these weeds get, you know, tall. I can let them get six, eight inches, and still kill them. Well, I think everybody would be in agreement that, you know, there's a critical period of interference, and, you know, eight inch tall weeds in corn far surpasses that. And you really don't see any, you know, fields of corn like this with any frequency anymore, because folks have gone back to using very strong residual herbicide programs. There are so many really effective premixes in the marketplace right now in corn, you know, that I've never seen in all the years of being in weed science. There are some absolutely stellar products. You could put the full rate on at the pre-timing. You could even do split applications. Maybe you do a two-thirds of planting time, follow up with one third post. But, you know, our base recommendation is always in corn, especially, you know, get something on there. It doesn't necessarily have to be real early in the season. We don't really like stuff out there 35, 40 days ahead of corn planting, like, you know, we used to do with some regularity. And part of that, you know, as we'll talk here a little bit later with the amaranths, water hemp is a species that has no trouble germinating and emerging for us clear through July and even into August. And so we're gonna rely on that corn canopy but we want try to get that canopy formed as soon as we can without very much weed interference. So, you know, loading up with effective pres, there's really not a lot that's gonna give us always season long control from a pre-standpoint. But again, depending on what we're dealing with, if it's not a glyphosate or glufosinate shortage issue, we've got some other pretty good post-products I think with a lot more flexibility in corn than maybe what we have in soybean going into 2022. - Yeah and I think that's kind of the key thing is thinking about where you might wanna use, you know, your glyphosate or your glufosinate, you know? If you're kind of limited on what you have, maybe don't want to necessarily put it on your corn acre. And I'm just kind of laughing because I remember some of those earlier applications that we'd go out in Illinois and thinking here in Michigan we'd be putting it on top of snow. So we don't usually worry about that too much. - You know, and the other thing, and I'll just bring this up now, but we're seeing a pretty significant trend here in Illinois. For years, Illinois was a corn first state. We planted corn first because that's what we did. And we got to planting soybeans whenever we could finish up the corn because that was the second crop, but with advances and some of the seed treatment technologies that we've seen on soybean seed, we're seeing a pretty significant shift now in people almost planting their entire soybean crop before they even begin planting their corn crop. And so that kind of pushes our planting time of corn back a little bit, you know. We used to always try to get in starting sometime in April, you know, when soil conditions were good to plant corn. Now we're planting soybeans the first week in April. Some are even trying the last week of March. So it's gonna push that corn planting a little bit farther down the calendar. And so, again, we're gonna hopefully have some flushes of weeds maybe that have already germinated and emerge that we can control ahead of corn planting. And, again, rely on our two-pass residuals, you know, start out with that good, strong residual. We've had some people suggest, and I think probably rightfully so, maybe if we had some glyphosate premixes that are labeled only in corn, use those. And then if you had a supply of just straight glyphosate or straight glufosinate maybe think about, you know, saving that on your soybean acres. - Yeah and I really do think that's a good idea because we do have a lot of alternatives out there for corn and we'll talk about where you can get some more information on that as we get a little bit further along in the presentation. So, you know, kind of looking at corn, we've got those options and we're starting to see a few more options depending on soybean traits, right? So with some of the newer soybean traits, and I always look at this and go, boy, we've got a lot of choices in soybeans, which can also cause a lot of headaches if you happen to be in the wrong field. And I'm sure you've seen that happen every once in a while. - A few times, unfortunately, yes. - Yeah, and that's maybe one thing we might want to bring up is, you know, knowing that we have all these choices and we do have a pretty good market up here for some of the non-GMO soybeans. So that's been a pretty steady acreage up here in Michigan, but obviously, you know, looking at all these different things that are herbicide resistant, whether it's glyphosate resistance with the Roundup Ready system and the Liberty resistance with the Liberty Link and then you've got the Liberty Link GT27s that you can spray both of those on and looking at some of the new extend type systems with Dicamba and Lists, so there's a lot of options for growers to plant and I know one thing that we've been thinking about lately is, you know, making sure that you're aware of what you're planting in what field and many times maybe it's not such a bad idea for one farm just to really focus on just using one of those traits so they don't forget what was where and it's always a little troubling when you get that phone call and say, oops, we had, yeah, we had some Xtend beans and we had some Enlist beans and they went in the same planter. So what do you do there? Or, you know, some of those different options. But what I thought I would do is just kind show, you know, from that survey that we had done earlier, what kind of just approximations. And again, this is a small sampling, of acreage that was planted in 2021. And then look at what some of the different people are thinking about planning in 2022. So if you remember correctly, in 2021, that was the first year that we had XtendFlex more widespread that growers could plant and you can see where that is. That's that blue portion, darker blue portion, of that pie. And we actually had quite a bit of Enlist E3 soybeans that went out last year. You can see there's kind of an even split for some of the other ones, again, the non-GMO soybeans. We've got, you know, some processors up here that that's a pretty good market with some potential, you know, increases in prices. But we asked some of those same people what they thought they'd be planting in 2022 and I would say things are pretty similar, maybe a little bit more on the XtendFlex, but definitely a little bit more on the Enlist E3 soybeans. And just curious to what you're seeing in Illinois, is that kind of a similar split, or are you seeing the majority of one way or another? - Well, you know, by and large, we do have some issues, well, not issues, but certainly some acres of non-GMO beans primarily, you know, for the enhanced contracts and the price premiums, but, you know, hearkening back again to some of our issues that we have around resistant weed populations, it's very, very difficult, and in many cases we don't have an effective post option, you know, especially for the waterhemp and a non-GMO soybean. There is none. They'll still try to use a pretty strong residual program. They'll come in with an early post and then maybe add another residual in with that early post application and try to keep the amaranths down. Our other splits, of course, would be between the Xtend, XtendFlex, and then the Enlist E3 technologies. And we probably hit somewhere close to maybe 60% of our soybean acres in Illinois, about two years ago were the Xtend soybean varieties. And a lot of reason before that, of course, you know, a lot of farmers felt like those were the highest yielding varieties that they could get ahold of. And certainly, you know, Dicamba would, effectiveness against some of our resistant weed populations. That certainly was attractive to a lot of people, but we've always had issues around off-target movement of Dicamba in Illinois. And it's really escalated since the technologies came in the marketplace. As a state, we are very heavy in custom application. We estimate that somewhere between 60 to maybe 70% of our corn and soybean acres are not sprayed by farmers, they hire custom applicators to do this. And what's happened, of course, with the issues surrounding Dicamba here in Illinois, when our state goes out to investigate a complaint, they're looking to see if there's been any violation of the label that's taken place and, you know, retail applicators are finding it very, very challenging to meet all the requirements on the Dicamba product labels. They're the ones, if they're found to be in violation of the label, they're the ones that get the warning letters, they get the points on their license, and then they get the fines. And many of our retail applicators have felt like, you know, they've tried to do everything possible to follow the label and keep the product where it's applied, but yet, they're still seeing their customers, who are seeing issues around soybean injury. When you have such a large percent of your acres being done by custom applicators and these are the folks who are growing increasingly uncomfortable, you know, with some of this off target movement, I think they're really gonna be looking at other technologies here in 2022. And by far and away I think we're gonna see a pretty sizeable increase in our acres of Enlist E3 soybeans in 2022. It may even surpass our acres of either Xtend or XtendFlex acres here. - So yeah, I know that that's been, you know, kind of a huge challenge down in Illinois, some of that off-target movement. Do you feel like, and I think this is probably one of the things that makes it a little bit more difficult, is because you have so many resistant waterhemp populations that they're probably having to rely pretty heavily on that Dicamba application later in the season where I think with some of our (indistinct) issues, maybe some of those earlier applications may not be as big of a issue as far as off-target movement. So I think it's always interesting to hear other states, some of the issues. - Well, you know, when the Dicamba soybeans first entered the marketplace in 2017, we were really hopeful that people would think about some of the lessons that we learned with Roundup Ready technology. That first came in the marketplace in '96 here in Illinois. By and large, at that time, a lot of applications were made to fairly small weeds. You know, four inches or less, right? Where you would almost like them to be. But over time as folks discovered how effective glyphosate could be, Now all of a sudden you started to see that four inches here now become four inches here. And, you know, we sprayed a lot of very large weeds because we could and obviously that led to some issues that led to some performance challenges with the trade and the evolution of resistance. So our hope was when Dicamba came into the marketplace that folks would say, okay, we need to go back and treat these and at the appropriate size, but that didn't always happen. And it's not difficult even to this day, what are we now, five seasons into having that technology, to see whether it's giant ragweed, whether it's horseweed, whether it's waterhemp plants that are, you know, somewhere eight to 12 inches tall before they start curling over from a group four (indistinct). I'm afraid if we're not careful we're gonna limit the longevity of this technology like we have so many others. - Yeah and I think as you talk a little bit more about some of those waterhemp issues, I think we're gonna need every tool in the toolbox, as you know, somebody might say. So kind of thinking about that, over the years I know you guys have preached kind of the same thing that we have is that, especially as we start looking at some of these post-emergence shortages, I think a lot of these soil-applied pre-emergence herbicide applications are gonna really be important, you know, making sure we have that residual out there, kind of similar to what you were talking about in corn. Do you see that as being a huge benefit and are there certain types of products that you like to put down on the acre? - Yeah, I really do. I think this is something in that it's a fundamental practice of good weed management. You know, I harken back to 2008. 2008 was the first year that we actually came out with very specific directions. As a matter of fact it was a five step recommendation process and we titled this, you know, Managing Glyphosate Resistant Waterhemp. And the idea was you would look at this list of five steps and you would start at number one and you would work your way south to number five and you would do all those in between there. And the reason that we had these recommendations like we did is because we kind of fudged a little bit. We titled it, you know, Glyphosate Resistant Waterhemp, but what we were doing is we knew in the background, so to speak, we had functionally lost ALS inhibitors on waterhemp. We had no control left over whatsoever, but we also knew that the frequency of resistance to the PPO inhibitors was growing very rapidly. And so I give you all that background to say that the first one of these five steps was not only would a soybean farmer use a residual herbicide. Our recommendation was you need to apply that at the full labeled rate for that soil type and not much more than seven or 10 days before you intended to plant. Now, remember, this is back in 2008. We had just discovered our first glyphosate resistant population two years earlier. So in January of '08 when I first got up on the stage on our extension meetings and started going through this recommendation, you know, 35 seconds into the presentation I had absolutely no credibility left whatsoever. How dare the university come out and recommend residual herbicides? That's just university trying to scare us. It's going to add cost to my program. It can't be as bad as what you're making it out to be. And you know what, when glyphosate doesn't work, somebody's gonna bring something else into the marketplace. So we heard everything. Well, I really don't know or have any hard data, but I would estimate our numbers now in Illinois going into, let's project out to 2022, we'll probably be somewhere 60 to 70% of our bean acres have a residual. Now I'd like to tell you it was because of the great recommendations we came up with, but that's not the case. It's not because of what I said. It's because biology is forcing this change. You know, folks are realizing that they didn't really want to accept the fact that there may not be an effective post option. You know, once these things come out of the ground. That's happened before. And so beginning with that good, strong, foundational residual herbicide program, fundamentally, I don't really ever foresee that changing. I think we're gonna have to continue to try to keep the weeds down for as long as we can and utilize every possible tool that we have. - Yeah and I think when you start talking about residuals and we start to see kind of a shift to using more of those, again, because of some of the resistant weed issues, but also when you start thinking about it, it doesn't take long for some of those weeds increase in size to where they're harder to control. But not only that, you're losing yield every day that that weed gets bigger and it's competing with that soybean crop or corn crop or whatever crop. So to trying to make sure that we start out to give that crop the biggest advantage possible. And I think those residuals are really important. I mean, this was a no-till field, so obviously a good burn down program's gonna be extremely important. So kind of starting out, I always kind of look at it as starting out clean and then making sure have a good residual down. - Yeah, anybody who ever questions, you know, Christy, the need for residuals in terms of weed growth, I always point him towards somebody who's had prior experience with palmer amaranth. I mean, there you've got a species that grows at just a phenomenal growth rate. You know, Larry Steckel shared a couple of photos with me years ago. He had a soybean field at a certain date. Literally 13 days later that palmer amaranth was somewhere around eight inches tall, you know, after it had emerged from the soil. So there's really no way that you can stay in front of some of these species or some of these resistant populations by going a total post anymore. It's just very, very challenging and very risky, quite frankly, to do that anymore. - Yeah, and kind of thinking about that, are there certain herbicide groups that you like to look at down as a pre, are there certain combinations that you like to look at, or, you know, especially looking at your guys's kind of weed spectrum? - It really depends, I guess, on what our driver species are, and for us, again, it's the pigweed, it's the amaranths. Our frontline, so to speak, products still for residual control of our pigweeds have, you know, PPO chemistry, whether it's a (indistinct) or sulfentrazone. We don't really use those by themselves. Most everything is in a premix with something else. So it's not hard to, you know, find a combination that maybe has good control of your pigweed population, but also maybe has a premix component that has better control of large seeded species also. We don't really worry so much anymore in soybean about trying to control annual grasses with the pre. We certainly use products, for example, like boundaries, something that has (indistinct) in it will give us some of that annual grass control. But by and large I think most of our residuals in Illinois for soybean were using those targeting the broad species. We still have some fairly effective post grass products. We don't really don't see a lot of widespread resistance to the ACC inhibitors yet. I think we do have more ALS resistance, especially in our giant foxtail because of all the years of using, you know, products like nicosulfuron for corn. But so far we haven't really seen any hiccups yet with a post-glyphosate application on our annual grasses yet. So again, our residuals, for us pro targeting, you know, the broadleaf species, and again those applications that take place for broadleaves, you know, 85, 90% of them are targeting amaranths. And then we'll find a premixed partner if we need something, some assistance on other species. - Yeah and that's kind of where we've been at too, especially as that waterhemp, the problems with waterhemp start to increase in Michigan and I would say that, you know, one of the other things is because of the whole horseweed mirror still issue, we've seen a lot of metribuzin go on acres to help pick that up. It's kind of crazy to think about that that herbicide's been out for a really long time. You know, one of those kinda steadfast soil applied soybean herbicides that we thought was gonna go away and it's probably on more acres now than maybe what it ever was. - Yeah, it's interesting because my advisor from a PhD was Dr. Lloyd Wax. And I think Lloyd first started here at Illinois back in the late '60s. So he obviously has, you know, a lifetime of experience looking at various active ingredients. We've been playing around with metribuzin, especially on some of our tougher waterhemp populations. The good news is that it's still very effective and it can actually give us longer residual control of something like a PPO resistant waterhemp population than our PPO inhibitors do. So after looking at this and giving this some thought for a while, I asked Lloyd one day and I said, Lloyd, why did we ever move away from using metribuzin in Illinois? And he said, I don't know. He said, it always was a good, effective product. It doesn't control everything. It's not a standalone, but certainly it had it's utility, it had a good spectrum of control, primarily on our smaller seeded broadleaves. So I think it's something that we maybe have been under-utilizing here recently. And, you know, we've got a project, I think you're gonna participate in it also, trying to look at does metribuzin really still have a good fit in our soybean systems across the Midwest given the fact that, as we'll talk, our length of residual and some of our resistant populations is getting less and less. - So, yeah, obviously if we get a good start with a good pre that's gonna be important, but that still leaves us with any of those weeds that come up later, right? So let's talk little bit about, you know, some of those post herbicide applications and particularly in soybeans and you know, some of the things we wanna think about and, I mean, what are some of your thoughts on just post applications? - Well, I like your list. Your first one here is product selection. Of course, in 2022, that gonna be potentially a challenge. What we've encouraged people to do is, flexibility is gonna be absolutely key, I think, in 2022. You gotta have a plan, you've got to have a backup plan, and we've gone so far as suggesting that you've got a backup plan for your backup plan, because we simply don't know if we're gonna have access to some of these post products. You know, I've had retailers tell me just a couple of weeks ago, they're still trying to get prices on these products and there's a possibility they might not even be priced until delivery time. And so that, how do you go plan around that? So the other thing we've really tried to encourage people to think about and actually do, if you've never owned or looked at a university-generated weed control guide. I think this year would be an absolute essential to have that tool because in the tables that you'll see in virtually every university guide, will be herbicide against a suite of different weed species. And so maybe your plan was to use product A, that was your first line. that's what you used before, but all of a sudden now, well, we can't get it. Okay, our backup plan is to use product B. Well, golly, it's a week before we want to post the field and we just found out we can't get that one either. So you look in your weed control guide and say, okay, you know, here's my target spectrum. What other active ingredients can I look at that maybe I can source for that application? So, you know, the product selection is gonna be a bit tricky this year, but I think we've got some tools and techniques to try to maybe take some of the difficulty, you know, away from it. - Yeah, and the interesting thing is depending on what soil pot or pre-emergent product that you have, you know, some of those are pretty good at controlling certain weed species throughout the season. You know, it doesn't control all of them, but it definitely maybe reduces the number or the types of that you need to control. And also the number of weeds. So that's where I always look at it. That kind of goes into that whole thing on application parameters because if you got fewer weeds to control, you obviously get better coverage. And I always think about, you know, waterhemp populations or palmer amaranth populations that just seem to be a carpet. And I think that's where those pres definitely at least knocking out part of those help to get some good coverage. - Exactly, yeah. I mean, you talk something like the small seeded broadleaves like the waterhemps, the pigweeds, you're not even talking 100 seedlings per square foot. You're talking thousands of seedlings per square feet. And it's just remarkable. I mean, you can actually look out across the field at the right time in the morning that's got a solid stand of either waterhemp or palmer amaranth and there's a red cast across the entire field. Well, that's that red coloration on the underneath side of those leaves. And when you see that, you know, that ought to be a little bit alarming that that's the density, you know, that these species will actually emerge at that can literally give the perception of it. You know, the soil color has changed, you know, when sun strikes that leaf surface like that. So anything, the good solid residual program that reduces that down without a doubt, you're gonna have, you know, better coverage. There's no such thing as one emergency waterhemp. If you ever go to a field and you identify the broadleaf, it's waterhemp, and there's only one emergence event, you've misidentified it, it didn't work that way. So the other thing that happens is you have these multiple flushes, well, you get a variation in the architecture then, right? Here's your ones that emerged close to when the soybean came up. Well, here's his cousin right here, and now you can actually get into a kind of an umbrella effect where the larger plants, the leaf surfaces of some of these bigger plants, can actually protect the smaller ones that are growing underneath them from getting a thorough dose or an adequate dose of the post-applied product to control it. - Yeah, and I think, you know, that kind of brings into a play that particularly we're looking at soybeans, all these different traits, you know, making sure that we're matching up those post products and there can be a lot of tank mixtures out there because sometimes they're not necessarily, especially if we don't have glyphosate to help clean up some of the more sensitive species, some of the tank mixtures you have potentially could cause some crop injury or even some potential tank mixture antagonisms and I know both of us have seen of grass antagonism with some of the different tank mixtures. And I don't know if you wanna touch on that a little bit? - Yeah. Well, one of the big issues that we've had for the last several seasons now is with our volunteer corn and the thing is, I guess really, I don't wanna use the word alarming, but it just makes you scratch your head because you've got a volunteer corn plant and things like clethodim, for example, are just absolute death on volunteer corn. But unfortunately when we have tank mixtures sometimes and we see this quite a bit now with tank mixes of our post grass products with either the Xtend technology herbicides or the Enlist herbicides, we can see this antagonism happening with some regularity. And it's not something that we've really been able to find, you know, a silver bullet solution for. This is one thing to do and it's gonna go away. It doesn't work that way if you want to have these tank mix combinations. So this year, I think, especially, for our retailers in Illinois, what they have told me is that they feel as though they have a good supply of clethodim based product for post grass control, whether it be annual grasses or, you know, we do have some fern grasses of course, but again, targeting primarily volunteer corn. But what they're unsure of is, you know, what happens if we do get antagonism on that tank mix? Are we gonna have enough product in the inventory if we have to go back and respray that field? And I think that's a very legitimate concern going into this 2022 season. So something like antagonism on grass species doesn't have to happen, and there's a surefire way to avoid it every time and that is simply to split the applications. So you literally could spray your post grass herbicide on Monday, turn right around, and spray your (indistinct) product on Tuesday. And you'll kill all the grass because there's not gonna be that antagonism that we can, and don't let me mislead, we don't wanna get antagonism every time that we combine these things, but the likelihood of seeing it increases quite a bit when these products are combined versus when they are applied separately. - Yeah and even if you could get the product, just remember a lot of these products are more expensive this year. So maybe that extra application cost is not as big of a deal as having to come back another time with that herbicide cost. - Yeah, I mean, it's possible, Christy, you hit the nail on the head. The application cost this year could pale in comparison to what the cost of the re-spray herbicide's gonna be because of the antagonism issues. - Yeah, so I think that's kind of a big thing. And then when we start thinking about some of these post applications whether it's in corn or soybeans, a lot of times we do put some of those residual herbicides in there, some of the group 15s like a metolachlor or a pyroxasulfone or acetochlor or some of those other ones that can help with control some of those later emerging weeds like some of the amaranth species and I think that's where I kind of wanna take us next is really talking a little bit about, I know we've talked a little bit about waterhemp and you've brought up some really good points, but I thought maybe we could delve a little deeper because you guys have had probably the most experience with different types of resistance issues as well as just some watch outs and things. I thought I would just kind of bring up, you know, what we know right now in Michigan as far as different profiles. Like I said, you know, you had mentioned that waterhemp is native to Illinois. It's also native to Michigan, but again, we were probably maybe 20 years behind you into where we really started seeing widespread problems. It was probably, you know, 2011 that I think we probably found our first glyphosate resistant waterhemp in Michigan. Before that, if it was in a field, it was just pigweed, right? So one of the things that, I mean, these are just some maps from our diagnostic clinic and which particularly Dr. Aaron Hills has been doing a lot of screening of some of the waterhemp populations when people have sent them in. You can see that obviously the glyphosate resistance is pretty widespread, but we've got some other populations that are resistant to some of the triazines, the group fives, and then, you know, at least one population where we've got ALS Triazine and glyphosate resistance and then in the last couple years we've had a couple populations where we've identified resistance to those group 14 herbicides, like a Flexstar and Cobra and I know that's one thing that you guys have had as more of an issue longer and it seems to be pretty widespread. So I thought I would ask you a little bit about that because you just talked about how important those group 14 herbicides are from a pre-emergence standpoint to control waterhemp. So how does that work with a soiled applied group 14 herbicide like a Valor or one the sulfentrazone products compared to something like a Flexstar or Cobra that's applied post? - Well, this is a really important concept. We've really been trying to hammer our folks here in Illinois for several years, is try to get them to understand that when we have something like PPO resistance, it's not just to the foliar applied PPOs. It's also to the soil applied PPOs. And that's a very, very important thing to remember. What happens a lot of times is this. Okay, I've got a field, a soybean field, and I want to go spray my Flexstar. I want put Cobra on it. I want to use one of the foliar applied PPOs. I make the application, everything was done correctly. I had the right nozzles, the right rate, the right additive, you know, the sun, the moon, the stars were in perfect alignment. We should have killed every waterhemp plant in that field but yet we didn't. Pretty obvious, okay? You can even send it off to a university lab somewhere, they can confirm. Yep, you do have PPO resistance in that population. So visually seeing the resistance to a foliar applied is easy, right? They don't die. They may be injured, but they grow back. But what you're looking at here, this is actually work we did, golly, probably over 15 years ago. The pots in the front are from a sensitive population. The pots in the back are resistant population. The numbers that you have in white, that's the rate of Valor that we spray those pots with. Now, our use rates range anywhere from two to three ounces of Valor per acre. So you can see that the pots in the far right hand column, at three ounces of Valor, we controlled the sensitives and we controlled the resistance. So somebody would say, well, golly, I use three ounces of Valor and it's not resistant to it. Well, hold on, you can cut that back by a factor of 10, and you're still controlling both of these, right? There's no plants at that 0.3 ounce rate of Valor. You reduce that by another factor of 10 and all of a sudden, wait a minute, we've got resistant plants that are coming up through here. So I always ask this question. I said, now, can anybody tell me what is the rate of Valor that I need to control a germinating or emerging waterhemp seedling at any one point during the growing season? And usually, say, everybody sits there in silence. They don't wanna say anything. And I said, it's right in front of you. Well, they still don't say anything. And I said, well, if I look at this graphic right here, I only need 0.03 ounces 'cause I'm still controlling that sensitive. Well, if that's all that I need, why in the world am I putting on 100 times more at that three ounce rate? I mean, I don't wanna spend any more money and I have to, but yet I'm putting it on a dose that's 100 times higher than what I need. Well, the reason that you do that, of course, is you want that length of residual. You want that three ounces to last, you know, 3, 4, 5, 6 weeks, as long as you can get it. But what half when you have this resistance is that once that concentration of Valor or Authority, it doesn't make any difference, once that concentration begins to decrease in the soil, it's gonna reach a concentration that's low enough that the only ones that are gonna come up are the resistant ones. The sensitives are still gonna be controlled, right? Because they're still controlled here at 0.03 ounces. So that length of residual gets less and less. Now, how much is less? We don't really know. Maybe it's a day less. Maybe in some other instances it could be three weeks less. But we look back at some of our data from years and years ago, back about 1996 to '97, where we did an experiment looking at that time it was Authority and the highest rate of Authority that we applied six weeks after planting our waterhemp control on a sensitive population was still over 90%. Okay? Fast forward to the last two seasons where we've had the same rate of Authority on a resistant population. Now at six weeks we are less than 40% control. So again, we've lost a huge link of that soil residual activity through this evolution of resistance. So, you know, when we talk about resistance, we're really trying to hammer home the fact this is not just unique to foliar applied herbicides. It happens to soil applied also. - Well, and with that, you guys have seen a lot of different kinds of resistance profiles in Illinois. And I think these are a few that I've pulled that you guys have talked about in the past. I don't try to scare people but it's pretty scary when you put them up on the screen, especially when you look at that seven way resistance, you know, you were talking about six different classes, looking at 2,4-D and Dicamba both being group fours, but I mean that's pretty scary when you start thinking about what we've been talking about from a standpoint of what our options are, right? We've been talking about using either 2,4-D or Dicamba to control some of these populations. And, you know, as you mentioned, one of the things that stands out with this one and I'll let you talk a little bit, we'll go on the next slide, talking about the group 15 resistance or the resistance to some of those are kind of what we consider pre-grass herbicides, but I don't know if you wanna mention anything about the 2,4-D and Dicamba as you look at that one. - Yeah. You know, it's funny. Well, it's not funny, but I guess I'm getting old. I keep telling the same stories over and over again. My colleague, Dr. Trail, and I, we were just so excited when we found the first population of waterhemp in Illinois that was actually resistant to herbicides from two classes. It was ALS resistant and Triazine. Boy, we were just on cloud nine. Then we found three, then four, and you can see where this is going. What you're looking at in this population on the right over here in the seven way. You know, one of the, I guess, really unnerving, if I could use that word, things about this population. I forget, I think we've published on this, maybe, what, 4, 5, 6 years ago about this 2,4-D resistance in this population. We've gone back in the farmer's records for as many years as we can. There's no history of 2,4-D ever being used on that population. And depending upon which sensitive that you want to use for comparison, this thing could be up to 30 fold resistant to a herbicide that was never are used in that field before. And so, you know, we always get people to think, now think about this conceptually. Can you have resistance to a herbicide for which this population of this field has never seen before? And the answer is certainly yes, you can. Well, carry that a little bit farther. What's most people think is gonna be the solution for all this? Well, somebody's gonna develop a new herbicide and it's gonna make all these problems go away. Here's the catch. It may already be resistant to that herbicide. Matter of fact, I know firsthand from one of our former students who used to work in herbicide discovery, that the company that they worked for actually had discovered a new site of action and they were continuing to, you know, move it through their early screens, their biology program at the laboratories. And then they screened it against one of these things. That new site of action now sitting on a shelf somewhere because they won't bring it to marketplace because there's already resistance to it. And so even though somebody, and somebody eventually will bring out a new act of a new target site, but there's no guarantees how long that's gonna be effective. The Dicamba that you've got circled here, when we first started working with this population, again, about seven years ago, we could still effectively control it with Dicamba. But starting about five years or so back we started noticing the field that the level of control kept getting less than a less. And we were looking at a half a pound at Dicamba. We'd go up to a pound and a half, and even at a pound and a half, we still found survivors. And so finally doing the appropriate dose response in the greenhouse when we were able to earlier, you know, confirm that we do have Dicamba resistance now in this population. So we've lost so many of our effective tools that for many, many years we relied upon and we're not gonna see a lot of new things coming into the marketplace anytime in the foreseeable future. So, you know, my preaching message to Michigan growers, I mean, stay in front of this thing. Don't do like we did here and think that there's always gonna be a new solution for this. There's not, you know, a lot of folks thought that, you know, the 2,4-D resistance soybean, a Dicamba resistance soybean was gonna solve all these problems. And the answer is not indefinitely. - Yeah, Aaron, so just to bring this up. The seven way resistance population. How widespread is it? Is it one field, one farm, one county? - Yeah, we have no idea. I mean, honestly, we don't know. We don't find any populations of waterhemp in Illinois that are sensitive anymore. They're resistant to something. It's just now a question of, well, how many somethings are they resistant to? And this is gonna continue to increase. What we know from previous work is, you know, even if, let's say we evolved glyphosate resistance, and we stopped using glyphosate for 10 years, and in year 11, we think, well, we'll go back and try it again. Maybe something's changed. Guess what? It's not gonna work even after 11 years because once these resistance alleles are in these populations, even in the absence of that selection, that resistance does not go away. So once you've got it, you've got it for good. - And I think what I'll do is we're getting pretty close to the end of the hour. I just wanted to put this up here and maybe you could just make a quick comment about your group 15 resistance and then we'll kind of end things. - Yeah, this is some work that we actually first thought we had something about this in about 2010, and it wasn't because of group 15s. It was actually HPPD inhibitor work that we were working on. And we noticed in some field experiments that the level of control with acetochlor was lot less than we normally associate. But yet the control with acetochlor still remained pretty effective. We dropped it simply because at that time we weren't looking for this. We were more interested in group 27 work. So when we had another population sent to us that I forget what they said, it wasn't controlled with one with post applied HPPD, on a whim we just put out a similar trial and all of a sudden we say, wow, we're seeing the exact same thing. So what you're looking at, this is typical results that we see about 30 days after application. The panels on the top row, that's a sensitive population and you can see what the products were. They're listed there at the bottom of each column. I'm sorry, the population on the bottom is a sensitive population, but the population on top is a group 15 resistant population. And every one of these group 15s that we've looked at, we can quantify the resistance. So even though a Harness or acetochlor looks like it's got better control than the Dual Magnum, and it does, you know, obviously in this slide, those plants that have already emerged, every one are resistant so we do have resistance across all the group 15s that we've looked at. - Yeah. Well, I definitely wanna thank you for spending your Monday evening with us because it's actually been enjoyable. It's been nice to able to do another extension meeting with you. I know we did a number of those when I was in Illinois and it's been great to have this conversation and just wanna put up here Aaron's contact information, mine, as well as our website. And remember, you know, the weed guide, it's gonna be really important this year. And I think, with that, we'll turn it over to Jim and he can maybe give some instructions on some things. And then maybe if we've got time for a couple questions. - Well, thank you very much, Christy and Aaron, it's been a lively discussion and I feel real good about how the program has gone tonight. There was a couple of things that came in early in the program when you were talking about the weed profiles kind of in Michigan and Illinois. And one was a question about bur cucumber. If you have any comments about that particular species. - I'll let Aaron handle that one 'cause I know that's been a big problem on the west side of the state of Illinois, and I think, probably, bur cucumber, they're probably talking about in corn, 'cause that usually seems to be the bigger issue. - Yeah, that's where we see most of the challenges with bur cucumber because those seedlings can actually emerge so late in the year. We may think we have a fully developed corn canopy and we're out of the woods and all of a sudden we come back two weeks later and it's just this big, huge, mass of vines. For us, back in the day when we could use 3, 4, 5 pounds of atrazine, that actually was fairly effective against bur cucumber. But the challenge of it is now with as late as it can come up, it's very difficult to have our soil residuals that give us that lasting effective residual control. Prosulfuron is very effective as a post-treatment on bur cucumber, but again, with the lateness that you would have to make in an application for prosulfuron, you're pretty much locking yourself into corn the following year because of carrying issues and concerns. - Okay, before I bring my next question to you, I wanna tell everybody that we've put the link to the survey that we invite you to fill out. It's in the chat, I just sent that out. Your access to one pesticide research credits for Michigan applicators and also certified crop advisor credit can be had at the end of that survey. One other thing that that came up was about cocklebur. As I mentioned, I'm in upper-peninsula Michigan. We had a grad student a number of years ago, 20 plus years ago, was working on a thesis or a dissertation and came up to Chatham where the MSU research station is located in my area and wanted to assess the adaptation of cocklebur that far north, including, I think, quite a continuum of, is it latitudes? North and south, anyway. None of them survived, thank goodness, or else they'd have tarred and feathered me and run me out of UM. But how far north do you expect that cocklebur is adapted? That's a hard question, I know. - Well, Christy, since you're north of me, I'm going to turn that one over to you. - Oh, well I can tell you I've seen it in Saginaw county. You know, Shaiwassee-Saginaw, kind of that border, I've seen a couple fields that have been pretty heavily infested. So further north than that there are probably some, but I haven't seen anything further north than that, but I think with some of the changes that we're seeing and some of the adaptations of some of those weeds, and, I don't know, Jim, maybe you should go back to some of those fields and start doing some digging. There might be some old burs there. And before we go, I do wanna, you know, thank Jim because he's actually retiring at the end of the month or at the end of this week, I'm sorry. That's why he is got a huge smile on his face, but he's been a tremendous asset to our extension team and just wanna wish him well. - Thank you very much, Christy. Thanks, Aaron. Before we sign off, are there any last questions? We'll give you a minute or two to type anything of interest to you into the Q&A. - You know, Jim, when somebody's writing here, I'll just share this observation with you. But you know we talk about the adaptability of weeds and maybe cocklebur being more adapted to the more northern latitudes, palmer amaranth is a really case endpoint sort of a species because this thing evolved in the Sonora desert. I mean, this is a desert evolved plant species from the Southwestern United States. And just last August, September, there is a news release that palmer amaranth has now been found in Manitoba. - Got a new question in the chat. What would you say to someone who is not having success with (indistinct) control with metribuzin? - So, I mean, a couple things, maybe the one thing we need to think about is the metribuzin rate. So depending on what that is and I know that's one of the challenges that we have on some of our sandier soils, you know, we've been doing some screens all the way up to a pound, but that's always kind of one of those issues, but if there is a huge issue from that standpoint, it wouldn't be a bad idea to collect some seed and send them in and have Aaron do some resistance screening. But the other thing is, you know, we do know that we can get some residual control from some of the flumoxes and products. At least, you know, to give it some kind of a start and then making sure that we got something post emergence. And again that's gonna be really focusing on some of those herbicide resistant soybean traits that we have. - Would it be fair to say that maybe one of the take home messages from tonight's discussion is that producers should continue to pay strict attention to their pre-emergent programs? - Yeah, I think that's really important. And you know, as Aaron said, both corn and soybeans, it's critical. - Yeah. I always try to use this analogy. It's like, you know, what do we call these areas that we pull these massive pieces of equipment into and we plant this very expensive seed in the ground, right? We call these things fields. No big surprise there. But these are actually biological systems and biological systems just by definition, they're never static. They're always changing. Might be weeds this week, might be insects next week, but something is gonna change over time. - Okay. One final question before we pull the plug. What's the best way to kill hemp dogbane in corn? - So we actually have a fact sheet on that in the back of the weed control guide and it's on the website so if somebody wants to go and look 'cause there are some different options that you can, some of the ALS inhibitors are actually fairly good on it. So you can choose but there was a lot of work done several years ago before Roundup, so we've got that information out there.

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