All about weeds

Shay

Foulk: Welcome back everyone to the Ag View Pitch. This is Shay Foulk and today I have on special guest Adam Striegel at the University of Nebraska-Lincoln. Can you introduce yourself, Adam?

Adam

Striegel: Yeah, hello everyone. So my name is Adam Striegel. I'm a graduate student at the University of Nebraska-Lincoln. I study weed science primarily in corn and soybeans and I was given the opportunity to join Shea to discuss some of the weed control issues many producers are having with the spring that we've had this year.

Shay

Foulk: I'll preface this by saying that Adam is one of the smartest and most dedicated people to weeds outside of the marijuana type of anybody else that I know. So definitely talking to the right person here today. Adam, can you tell me a little bit about the research that you're doing on your end?

Adam

Striegel: Yeah, first and foremost, Shay, now I'm blushing. Thank you for that. In my graduate research, I work primarily with two main projects. We have several different industry-side projects that my advisor makes me do as well, but the two projects that I work primarily on, the first being volunteer corn control in the Enlist corn systems, and the second being comparing different pre- followed by post-herbicide programs in soybeans across the state of Nebraska. Did you want specifics as well?

Shay

Foulk: Yeah, let's talk a little bit about, you know, if you could talk for 2 minutes here about what those actually look like.

Adam

Striegel: Yeah, most definitely. So for the Enlist corn project in Nebraska, with having a lot of center pivot irrigation and highly productive land, a lot of producers do corn on corn crop rotations or corn, corn, corn followed by a year of soybeans. In these cropping systems, we've noticed an increase in, in specific years of volunteer corn in their corn fields. In 2017, we had a really bad windstorm that dropped a lot of ears right before harvest, and that following year, the volunteer corn in these corn fields was incredibly bad, to the point which they were reaching out to my advisor about you know, what are the yield loss potential of these volunteer corn plants in my cornfield, or how can I control them in my cornfield? And up into that point, there hadn't been a lot of research done on the yield impacts of volunteer corn in a cornfield or how to control it in a cornfield.

You know, if you think back, you used to be able to rotate between Roundup Ready and LibertyLink corn, so that was a good way that we used to be able to control volunteer corn, but with the prevalence of these smart stacks that stack these two traits together, that management program has kind of gone by the wayside. So with Enlist, it's resistant to all the FOP herbicides in the ACCase group. So you're, you know, you're looking at Asure II, Fusillade, or Fusion. These are products that you could spray in Enlist corn and control volunteer corn from the year prior. It's a new management tool. And did you want me to jump right back into the soybean project?

Shay

Foulk: Yeah, no, that, that, and that's interesting. So one quick note that I'll make there on that, and you and I were talking a bit about this offline there, but when, as we move forward, so, you know, Enlist, obviously exciting lineup there. As we move forward, if there are fields that are corn on corn and you have the volunteer from Enlist, what does that look like? How do you control that down the road?

Adam

Striegel: That would be incredibly difficult to control in a corn on corn crop rotation. If you're not willing to utilize a crop rotation and plant soybeans, for example, the products that you could use to control the volunteer Enlist corn in a cornfield is next to nothing. If you were using soybeans as a rotation crop, then you could just use any of the other ACCase herbicides like clethodim, which would be Select, or Poast, which is sethoxydim. But in a corn-on-corn crop rotation, it would become incredibly difficult to control volunteer Enlist, which is why, you know, variety placement in your rotation is probably essential.

Shay

Foulk: Right, obviously some long-term decision-making to be made there. Now let's talk a little bit about the soybean side of things then.

Adam

Striegel: Yeah, most definitely. So, you know, I think no one is more aware of the options that you have in herbicide-resistant crops than, than producers and farmers. With the Xtend trait being widely adopted and Enlist soybeans coming out soon, there will be more options for your, you know, herbicide-resistant soybeans than we've had ever. And so this project looks at, you know, the ability to control weeds in conventional herbicide programs, Roundup programs, your Xtend programs, and your Liberty programs. And that is a pre followed by a post program. So not only are we looking at these different post programs that go associated with different herbicide traits. You're also looking at different pre-programs, trying to really look at what is one of the better herbicide programs that you can use based off of your state in, or excuse me, your location in the state.

So that way you can get the best bang for your buck in terms of weed control.

Shay

Foulk: Sounds like you're looking at a lot of variables there.

Adam

Striegel: Yeah, it's made the analysis kind of interesting, but the one thing I've really enjoyed about this project is that we have a multi-site location. So I've gotten to travel across the great state of Nebraska and look at, you know, different production practices as we move across the state. And, you know, when you move from a dryland farm to an irrigated farm to all the way out west in Scottsbluff, you do see a lot of differences in some of the management practices that producers use.

Shay

Foulk: And that's a good follow-up question that I had for you. You are looking at variables between dryland, irrigated, and otherwise?

Adam

Striegel: Yes, so that is a— that is one of the layers associated with this project. So we have both dryland, irrigated, and those are primarily the two differences that we have. But then we also have differences in tillage operations, whether it's a conventionally tilled field or a no-till field.

Shay

Foulk: Okay, great. Now thank you for sharing that side of things, and it's a good segue into one of the primary questions why I'm talking with you today, and that's current weed pressure and late season control. So producers have finally gotten a breath of air, hopefully, uh, planting's done, side dress operations or late season nitrogen if they have the capability for that or if that's part of their program. Now they're looking at weed control, weed pressure, and there are a lot of producers out there that are going, oh man, lots of issues right now. So I want to look at it from the standpoint of not only those that were prevent plant acres, but the wet spots that you have remaining in the field and just traditionally heavy areas of weed pressure.

So talk to me a little bit about how this year was different as far as timing for weed emergence and then some of the decisions that producers had to make with that.

Adam

Striegel: Yeah, most definitely. Um, so what we saw in some of the research plots that we work with is two actual things. In one area where it got a little less rain than some of the other locations, the weeds emerged just kind of normally, your standard timing of the different weed species, whether it be your amaranth species, your horseweed. Then in some areas where we had very heavy rainfall, the weeds were also delayed in emergence. For example, That soybean project that I was talking about earlier, one of my locations, it— we're probably 40 days after we applied the pre, and we haven't seen a break or weed germination in the plots that received pre-herbicides, which was really surprising to see.

Shay

Foulk: Yeah, that's pretty incredible. That's the product doing what it's supposed to be doing. Yep.

Adam

Striegel: Uh, and with depending on the product that you apply as well, the amount of rain that you received. And if you got your herbicides on prior to a lot of the rain events that we had, you could have saw increased efficacy, but you could have also seen a breakdown of products if it moved it through the soil profile.

Shay

Foulk: Interesting. So the areas that were not able to get that in in time, and maybe you haven't seen a whole lot of that, but I know, so Northwest Illinois, Northeast Iowa, and really kind of on the eastern side of the,, the Corn Belt, even into Indiana here, there's a lot of producers that were not fortunate to, to get anything on before that. So they're seeing this really heavy weed pressure. Now, have you seen any differences? Uh, you mentioned there are some farms with different cultivation practices as well as product management. How has cultivation or tillage passes played a role in that?

Adam

Striegel: So that's actually a great segue. Um, so for the project that I was discussing The location I was talking about that we had excellent weed control, that is a conventionally tilled field. Another one of the locations that I have is a no-till field, and they start off a little dirty. And, you know, that's not something we weed scientists like. You know, one of the things that we stress to producers is, you know, we start clean and you stay clean. That's the ideal scenario. But in, you know, this spring, this year, that's been very challenging for a lot of producers. That, that specific field location where we started a little dirty, it got even more dirty with the delay of planting and some of these herbicide program applications. So I think I'm seeing kind of similar results to what we were seeing, what you're seeing, I guess, in the eastern Corn Belt.

Shay

Foulk: Right. With, with that being said, so we've talked about where we've been, We know where we are right now, where are we going? So I guess to implement more on where, where we are right now, what can producers be doing right now in order to turn some of these issues around?

Adam

Striegel: Yeah, most definitely. So if we're, if we're working with a primarily heavy weed infestation and large weed size, you know, that's, it's important to look at not only species composition but also species height. Some of these products are a little bit more flexible in terms of what we can apply for weed height versus others. You know, it makes sense, Shay, if we were to apply a contact herbicide, you know, the only part of the plant it's going to kill is where it comes in contact with the specific leaves or other plant parts. So with larger weed size, a lot of these contact herbicides that we would— we could primarily use in a normal year may not be the best fit for our certain situation, to the point where I'd be looking at more of our systemic herbicides, which there's probably no more popular systemic herbicide than glyphosate, followed closely by 2,4-D and dicamba.

So when we're looking at these larger weed sizes, you have to come up to bat with the right herbicide, I guess.

Shay

Foulk: Oh, that makes sense. Now how about on the smaller end of that?

Adam

Striegel: So with the smaller end, if your field has smaller weeds, you know, a lot of these contact herbicides will still work great. And depending on if you got a crop in or if you didn't, this is an opportunity. You know, I think we talked about, we would discuss this in the prevent plant section, but you know, this is an opportunity to maybe utilize a herbicide that you haven't used before. Like if you've not traditionally used Liberty on your farm, and you weren't able to get some acres in and you're looking at a prevent plant situation, this is an awesome opportunity to utilize a chemistry you don't typically use and give the weeds a little bit of a diverse experience with our herbicides to hopefully prevent the development of any resistance on your farm.

Shay

Foulk: And that's some of the whole premise behind proper weed control, right?

Adam

Striegel: Yes.

Shay

Foulk: I mean, let's look at— let's not look at one knockout punch here. We need 3 to 4 modes of action, and that's what you're alluding to here. Uh, we need to look at areas that if we've moved to no-till or strip-till systems, if this is a year where you're having significant pressure, you didn't get the crop planted, or you have large areas that didn't make it after 1 or 2 replants, you may need to be considering some other options.

Adam

Striegel: And, and there's an interesting point that I talked to my advisor Amit Jalla at UNL about because, you know, one of the locations that we were spraying had exactly what we're discussing about some of these, some, in some of these farmers' fields. They have large weeds that weren't controlled or taken care of by a tillage operation or burn down, and we needed to apply some of these products. And I discussed with him, you know, is there any, has there been any studies that have shown that a field that has, you know, high weed populations that are already present in the field, is that going to prevent some of these molecules from getting down into the soil to provide residual control to any of the seeds that have yet to germinate?

And he was telling me, based off of what he's seen and what he's read, that there hasn't been a study that has identified that a ground cover will prevent some of these soil-applied herbicides from working. That surprised me a little bit., but if it gets down to the soil like it should, we shouldn't see a reduced efficacy just because you have weeds in your field. And that kind of makes sense when you think about what a lot of producers will do in the spring where they throw a burn-down herbicide in with their preseeds.

Shay

Foulk: Right, that's a really interesting point. Talk to me a little bit about the importance of residuals.

Adam

Striegel: Yes, absolutely. So, you know, Shay, if you have a really bad waterhemp population in a field and you need to control it and you kill it. Is that, is that gone or will it come back? Kind of like, um, what— there's a Greek— there's an animal in Greek mythology, I believe it's the Hydra. You cut one head off and two come out of it, right? You can control a stand of plants with, you know, either a contact or systemic herbicide, but if you don't apply some sort of residual product and there are seeds waiting in the soil, in the seed bank, that are able to germinate, then you're just going to have to come back with a second pass almost.

But if you apply some of these contact or systemic herbicides in conjunction with a residual product at the same time, even though this is, you know, at this point post-emergence, you will see a longer period of weed control because your residual soil herbicide will be putting in the work for, you know, 14, 28, maybe even 40 days depending on where you're at and what your field's like.

Shay

Foulk: You threw me a really good pitch there. And that leads into another question that I had for you. Producers that are renting new ground, have recently purchased from other ones that have traditionally had poor weed control. I'll ask this two ways. So the first way is timeliness. And the second way is economically. So as far as timeliness goes, How long can producers expect to have to have these diligent programs to get real heavy weed areas under control?

Adam

Striegel: You know, I would say that it's, that's gonna be what an agronomist would say. It's a great, you know, cop-out answer. It always depends, uh, you know, based off of species composition, the original density, and the management practices of that field. It's going to vary on a case-by-case basis. But if we want to talk in specifics, you know, if we think about the seed bank dynamics of a field being a living entity, obviously you're going to have to control for multiple years. So, and based off of your weed composition, you know, I think, and it was an undergrad, the weed scientist that I took one of my classes with told me like velvetleaf can remain viable in the soil for up to like 30 or 40 years.

Shay

Foulk: That's pretty incredible.

Adam

Striegel: Yes, but obviously that's on one end of the spectrum. Some of these smaller seeded plants, like for example your waterhemp species, the seed reserves that they have in terms of viability over time decreases rapidly. So based off of your species composition, you're probably going to have a better look at how long you're going to need to control a specific field, but the main takeaway answer from this, from from this question that you asked me, and it was good, is this is a multi-year experience. If you have a new piece of ground that has had poor weed control, you're going to have to put in due diligence and time and money to control the last producer's mistakes.

And eventually, you know, with time, you will be able to probably back off on that, but it's essential that you keep up with it in these, in these first few years., and it may be more expensive than some of your other acres, but you know, you're looking at a long-term investment probably if you purchase the farm. And if you're renting the farm still, if it's a multi-year agreement, you're looking at trying to maintain a, you know, income from those acres, not just one year, but two, three, or however many years your agreement is for. I don't know if that answered your question.

Shay

Foulk: It did. And you mentioned money and expenses there, which leads me to the second part of that question. And A lot of producers are in a tight area right now. I mean, yep, your working capital, your line of credit is real tight. Margins are a little bit better with the increase in market price. But who knows what happens here as we get into the end of summer and early fall to see how this crop actually turns out. So I mean, and I know it's hard to quantify, but taking the time and the money to do this now, it pays economic dividends down the road, am I right?

Adam

Striegel: Yes, and that's something that I do want to stress that I've seen, you know, growing up on a farm I saw this, and I know a lot of producers do the same thing, you know, picking a herbicide program without looking sometimes at the weed populations in your field. The best thing that you can do with your retailer or your agronomist is visit, visit your fields, scout, see what's there, and see if the herbicide program you're planning to put on Do you really need all the products that you planned on using, or are you not addressing a specific weed problem that isn't in the portfolio of the control that some of these other products provide? So it makes sense, match a herbicide program up to what you have in the field. With some of these situations, you can get by with some of those older non-patented herbicides. That can, that can be a source of cost savings.

But for some of these premixed herbicide programs or products that are very popular, they do come at a price premium. But, you know, they come with these different surfactants and crop safeners, and sometimes that's a little difficult to create on your own by mixing some of these old non-patented versions. You know, that said, I would definitely look at exploring any cost savings cost-saving options that you have at your disposal. But, you know, don't extend yourself past where you're comfortable making choices, I guess.

Shay

Foulk: Great points, uh, staying inside of that comfort zone for your economics, but at the same time making sure that you're controlling the issue. Um, let's turn quick to, uh, cover crops and how they play into this picture. So as far as weed controls, talk to me a little bit about the importance of having ground cover there in the first place and also competition with these weed species a little bit.

Adam

Striegel: Yeah, most definitely. Uh, so, you know, depending on who you talk to, cover crops are the next best thing or one of the dumbest things known to mankind. I kind of, I kind of fall in the middle. I think that there are times and places that cover crops are absolutely fantastic to implement into our cropping rotations, but But if it doesn't fit a certain scenario or your economics, you know, it's not something that you should explore at that current time. But, you know, don't feel like you can't come back to that option as you move forward with your, with your operation. It has to fit into your system. And one of the places I think that it's really going to fit in well this year is a lot of these prevent plant acres. You know, you mentioned how cover crops interact with weed species and also ground cover.

I worked for a professor for a summer looking at a lot of those type of, a lot of these type of experiments using cereal rye at different density rates and different termination times in corn to control weeds. And what we found is, you know, if you can nail that termination time and you don't cause a competition for moisture or nutrients in your crop, crop, the residue, the stubble of that cereal rye was an absolute fantastic tool to use in our weed management programs. With a lot of these programs not using either a pre or a post herbicide program or different timings or rates, we found that the residue from the cereal rye, even after it was terminated, was a fantastic tool for use in weed control. And, you know, that's after it's been terminated and died and it's just laying down on your soil surface.

But we're talking about an active living crop, cover crop specifically, in these prevent plant fields. You know, it's an opportunity that growers have not only to, you know, hopefully prevent any unnecessary soil erosion and protect that soil surface,, but also, as you said, to compete with these weed species and, you know, also throw a little bit of diversity in their cropping rotations. You know, let's think about our common corn-soybean crop rotation. When was the last time some of these fields, you think, saw like a brassica species, your mustards? Probably a long time ago. Yeah. So it's an opportunity to inject a one year or a couple months of diversity into your system that it may not get to have for quite some time. But what it really comes down to is, is the economics, you know.

Is it going to be economical for me to apply these cover crops to these prevent plant acres, and will I get the control I want with these species by itself, or will I have to also include a tillage operation or a herbicide application? And I would probably say Your best bet would be to start clean, plant your cover crops, and then based off of that, you'd be moving forward with, you know, do I have any post-emerge herbicide programs that I could put in these cover crop areas, or is my pre and my cover crop going to provide me enough control? You know, there's a lot to discuss on specifically cover crops just in general.

Shay

Foulk: Yeah, that's a lot of good, you know, advice or even, even perspective on that. I won't even call it advice, just some perspective on all the different options that producers have. Because back to our point earlier, it's not just a one-punch knockout, it's a 1, 2, 3, 4, let's give them an uppercut after that, and kind of managing it, managing it right is how I'll say that.

Adam

Striegel: Exactly.

Shay

Foulk: One thing that you had mentioned offline too, and I'd like you to speak to this real quick, is looking at making sure that you're planting the appropriate species as a cover crop. Can you just reiterate what you mentioned earlier?

Adam

Striegel: Yeah, most definitely, and I'll add a little bit to more than what we just discussed earlier. So, you know, when you're picking a cover crop, either blend or species, to put onto your field, you need to make sure that you're either working with your ag retailer or your extension service to make sure you're adequately choosing a species or blend to meet your needs. You know, if you're wanting to add organic matter into your soil, that you're going to pick different species than what you would for if you want to, you know, cause— improve your soil infiltration rate with like tillage radishes. If you're— and then also whether or not you're addressing what you're going to plant the next year.

You know, if you're going into a corn, uh, you know, the next year you plan to plant corn, we're these prevent plant acres are this year, you need to be looking at, you know, do I have any grasses in the mix so that way I can feed my mycorrhizae fungi in the soil so that way we don't have issues when I plant corn the next year with a low mycorrhizae count. Um, but, but so those are all things you need to think about, but probably the utmost most important one that I would think about when it comes to picking cover crop varieties is making sure that I stay within the rules of my prevent plant program. You don't want to accidentally plant the wrong crop and find out that you've put your payment for the prevent plant program in risk or jeopardy of being, you know, canceled because you planted the wrong thing.

You know, you mentioned earlier that you were talking to some producers that were discussing potentially just planting soybeans as a— just to cover the ground because they had the seed, but that is a harvestable, you know, insurable crop, and that would not fit into the prevent plant rules, uh, from my understanding. So, you know, make sure that you're following the rules associated with these prevent plant programs.

Shay

Foulk: And the key there, if you have any questions, contact your FSA office, talk to your agent, and make sure that you're making the right, the right decisions there.

Adam

Striegel: Exactly.

Shay

Foulk: Uh, so Adam, I guess as we, as we wrap up here, any last thoughts for, uh, the people, the listeners out there on what they, you know, anything to leave them with as far as weed control, what they need to be thinking about.

Adam

Striegel: Yes, absolutely. Um, so I guess I'm going to finish talking about these cover crops, and then we can maybe go into a no cover crop where you got your, your field in but just a little late. Um, you know, if you are planting or planning on planting a cover crop and you're looking at herbicide programs, there's two different schools of thought that you can use. The first is picking your, your cover crop species based off of the herbicides you need to spray for your weed pressures. And the other is picking your herbicides based off of your cover crop program. You know, those are two different schools of thought that are wildly different. I could have you plant different species or spray different herbicides, but I would say with this year having, you know, this is a large issue for a lot of producers in a lot of states.

I wouldn't feel comfortable only limiting myself to one or the other. I would look at the options you have on both ends. What seed can I get to my field when I need to plant? And what herbicides can I get to address the weed control issues I have in my field? And try to play the best of both worlds from those two schools of thoughts, I guess. Um, and it's important also to note that this is something I was discussing with another one of our Extension educators, Um, is that, you know, with some of these herbicides, you— they may not be labeled for a fallow application. So if you decide to not plant cover crops and you're not plant— choosing to plant anything in your field and you're just going to do a prevent plant and that's it, you, you need to make sure that the herbicides you want to spray are labeled for like a fallow application.

Uh, otherwise you're looking at I don't know if it's the farmer themselves or if the county has to do it, but there's a 24, Section 24 for one of the herbicide acts, which, which allows local use for an emergency of some of these products. You know, make sure you're not going off-label basically.

Shay

Foulk: Great point. You mentioned Extension there. Anybody listening, are they able to either reach out to you, and if so, how would they do that, or what are some of the resources that you recommend if they have questions? Here.

Adam

Striegel: Yeah, most definitely. You know, if someone wanted to reach out to me, I will do my best diligence to pass them on to the next person who would be the best appropriate to suit their need. Um, my contact information, I don't know if you want me to share it right now or if you'll go ahead.

Shay

Foulk: Yep, that's fine.

Adam

Striegel: Uh, my email address probably be the best way to do it, um, which would be adam.striegel.com. R-I-E-G-E-L, and then that's @huskers.unl.edu. And I will try to get any inquiries to the right person as fast as I can. So that's one avenue. And then the next avenue is, you know, you said when you were introducing the podcast series is that you have listeners in a lot of different states. I may not be able to address appropriately a, you know, a producer's questions. So if, if they're not in Nebraska or relatively close by, if you are, you know, not so close to where I am, I would not hesitate to contact your local Extension agents or maybe even your, your ag retailers with questions because, you know, everyone wants to make sure that we succeed in this really rough spring.

And I would, I would hope that we can find the information that we need, whether it be from me or Extension or maybe even just industry as well.

Shay

Foulk: And some people may have gotten to the point in their operations that they felt comfortable with their programs for years and years and years, but I would argue that this is a unique year with a lot of unique situations. So reach out to those people if you have questions. Hey, thanks a lot for joining us here, Adam. I really appreciate your time.

Adam

Striegel: No, thanks for having me. This has been a great experience, and hopefully your viewers found my rambling useful.

Shay

Foulk: Well, they'll, uh, they'll certainly be able to tell us if they did. Thanks everyone out there for joining us on today's episode of the Ag View Pitch, and we'll catch you next time.