A Practical Guide To Residuals, Nozzles, And Timing In Cotton Weed Control

A herbicide pass that misses is not a “learning moment” in cotton, it is a bill you pay all season. With drought across the Cotton Belt and budgets under pressure, we sit down with weed scientists Dr. Charlie Cahoon (NC State), Dr. Sarah Gansky (Kansas State), and Dr. Larry Steckel (University of Tennessee) to get brutally practical about optimizing cotton weed control without gambling on luck.

We dig into what they told growers to protect even when commodity prices are low: keeping residual herbicides in the program, getting activation when rainfall is scarce, and staying ahead of Palmer amaranth and tough grasses. Then we move into the mechanics that decide whether products like glufosinate (Liberty) deliver: nozzle selection, droplet size, sprayer speed, pressure, and spray volume. We also talk through the real tradeoffs between 15 and 20 gallons per acre, because water hauling, refill time, and label restrictions can matter as much as the chemistry.

Next comes timing and tank mixing. “Bankers’ hours” can be the difference between great Liberty performance and a costly redo, but other herbicides respond differently to sunlight and conditions. We unpack tank mix antagonism and why pairing auxins like dicamba or 2,4-D with grass herbicides can quietly cut control, plus what resistance is forcing in places where Palmer amaranth, ryegrass, and glyphosate-resistant grasses are rewriting the rules. We close with forward-looking tactics like lay-by residuals and ryegrass planning before the next season starts.

Subscribe for more cotton agronomy, share this with a neighbor who is about to spray, and leave a review with the one application detail you think most people overlook.

Transcript

Cold Open And Theme Song

SPEAKER_05 0:01

Well, what do we do? You call me the moon and then I wish I would take it. I think it's not even away from gold, but it's still the only life I did. Well, I finally made some money. It's the cotton picking cotton grooving blue.

Why Weed Programs Break In Drought

SPEAKER_03 1:03

Welcome to this episode of the Cotton Specialist Corner Podcast. My name is Campan, Extension Cotton Specialist based out of Tifton, Georgia. And continuing with a few of the podcasts that we've already done this year and talking about optimizing inputs, I've got a few weed scientists on the line here to talk about optimizing inputs with respect to weed management and a few different things that we need to take into consideration. This year has already been complicated for a lot of people in terms of the drought that's so widespread and giving us a lot of questions in terms of weed management of what we need to be doing. And because a lot of those things that we talk about in terms of a good, strong weed management program hinge on those early applications. And so we want to make sure that we're doing the right things and getting those residuals activated in situations uh where we can. But certainly uh got a good group today, got uh Dr. Charlie Cahoon at NC State, Dr. Sarah Gansky at Kansas State, and Dr. Larry Steckel at the University of Tennessee. So glad you guys could join us. And uh real quick, just kind of wanted to get into uh, you know, planting has been underway across the belt and in Texas since February, right? But we're kind of entering uh into some of these situations where people are making their first or potentially even second trip uh across a cotton field with a sprayer. And so what are some of the things that you guys gave advice about over the wintertime, kind of before we get into some of the particular things that we're gonna talk about? Just advice that you gave your growers going into 2026 with the situation we were looking at. And Charlie, I'll start with you and we'll work our way back towards the West.

What To Keep When Budgets Tight

SPEAKER_02 2:49

Yeah, yeah. First of all, thanks for having us, Camp, and uh good to be on. So, yeah, a lot of time we spent during the winter was was considering that commodity prices were so depressed, and and we knew that folks were gonna be trying to to squeeze every uh penny out of the acre. Um, so we focused a lot of attention in terms of the weed control, right? We, you know, we knew that folks were gonna be looking at cutting back. And so what were the things that we thought folks should keep? What were the things we thought folks could maybe trim some fat? And so number one at the top of my mind and my advice to our growers was we wanted to keep residuals up front uh behind the planner because you know, our our theme for for weed management across crops is start clean, stay clean, and and you can't start clean if you don't use a residual up front. And we know that's a a cost, and a lot of times, folks, that's the first place folks want to look at cutting out some costs. But I truly think if we're gonna start the season off right and not play catch up all season long in terms of chasing weeds, we got to have a good residual. Now, in the past, you know, we would talk about two and three and you know, maybe even four-way mix. Um, but but I was just hoping that folks would would see the the benefit of using a residual. Maybe we go to a one or two tank mix uh type product that we could have some savings there, and at least we've got some coverage on starting the season out clean. And hopefully uh we got them activated. That was a little bit tougher this spring with the the how dry it was in in the later part of April and moving into the first of May. But we've we've got some rains here more recently, and and I would suspect that we probably got a bulk of our residuals on the cotton acres that we got planted in May activated. So hopefully we've started the season off on the right foot on those acres for sure.

SPEAKER_03 4:39

Yeah, sure thing. Yeah, you know, it's if you look at a map of the drought monitor as it stands today, and we're recording this in the middle of May, right? Everywhere in the cotton belt is in under some kind of drought. And so certainly uh still need a little bit of relief there. But uh, Dr. Steckel, what about you? What was your message this past winter?

SPEAKER_01 4:59

Yeah, good to be with y'all. Kind of one of my main messages was you know, the most expensive application is the one that doesn't work. So a lot of the block and tackle stuff, um you know, especially with things like glyfosinate and liberty, you know, time of day, when you spray it makes a big difference. So you know, spraying it during bankers' hours, 10 to 3, uh, you're gonna get the best chance of getting good results with it. That was one of the fundamentals, but you know, novels, uh, you know, on things like contacts again, like Liberty, uh, getting good coverage with those, you know, things like that. Just kind of the block and tackle stuff, uh using uh a residual herbicide and overlaying another one we're we're struggling to control, especially well. Remember the grass species, goose grass and banyard grass and palm ramaranth with anything post. So residuals are really the most consistent thing. But like Charlie just said, if you don't get it rained, don't get them activated, then you gotta be Johnny on the spot with those posts. So uh those were some of the main take homes uh that that I had this morning.

SPEAKER_03 6:05

Yeah, for sure. And you know, you you mentioned that the the most expensive one is one that doesn't work. And we say something similar around here, the most expensive one you make is the one you make twice, you know, and it's same thing, right? Because you're gonna have to make a second trip and clean up that that uh first application. So certainly echo that for sure. So uh Dr. Gansky, what about you?

SPEAKER_00 6:30

Yeah, so here, so Kansas, I'm thinking, is sort of the fringe acres for everything. We're fringe acres for corn and we're fringe acres for cotton. So, you know, my environment is quite a bit different than what Charlie and Larry see. So we kind of fight this battle of always being on the edge of a drought or in a drought throughout much of our cotton production region. In fact, I would say we've been in pretty significant drought in some of my cotton farmers for the last several years. So we do emphasize the residuals. And I do Charlie talk a lot about making sure we keep at least two. And the spin that I put on that, and and y'all can tell me I'm crazy if you think I'm wrong, but the spin I put on that is that I want one that has high water solubility and I want one that has lower water solubility. That way I'm covered with something that will activate quickly, with that, you know, we we joke around here that the two inch rains when it's two inches between the drops, right? Um, with something that will activate with a little bit of rainfall, and then also something that can stick around a little bit longer. So we've spent a lot of time this winter talking about that. We spent a lot of time this winter, not much like Larry said, talking about glufosinate. And in here, you know, yeah, bankers hours are good, but we spent a lot of time talking about the role of AMS um in terms of making glufosinate work better.

SPEAKER_03 7:53

So yeah, for sure. And I mean, out there, right, it's it's dry. And so in the in this humidity that we have in the in the mid-south and the southeast, you know, that's not as big of a concern, right? But certainly out there in Kansas and Oklahoma and Texas, that becomes a lot bigger concern. So it sounds like everybody was on the same page. And and that's interesting you bring up the the water solubility. I've never thought about it like that, but I do the same thing. Like on some of our stuff on on the station, from nine times out of ten, we're gonna do reflex and warrant. And if we get an inch and a half, the reflex ain't doing much for you. And but you still got something to fall back on. So certainly a good piece of advice there.

Nozzles, Droplets, Speed, And GPA

SPEAKER_03 8:34

So let's get into some of this stuff that you know, we're we're getting into this time of year where these folks are making their first trip across the field. Like I said, we mentioned some stuff about pre-herbicides and getting activated and and different things like that. But we we mentioned also that you don't want to make a mistake and have to go back again, right? And so what we'll do is kind of go through a few things that I think about a lot or in terms of optimizing weed management with a herbicide application for certain. Uh, and then we'll kind of bounce some stuff back and forth, and you know, we can talk about droplet size and nozzle type and and even sprayer output all together and uh a few things in there, right? And you know, I would encourage folks, we've already released the episode that uh Dr. Culpepper and Dr. Dotre did with us on Dicamba. There's a lot of legality in some of that stuff, and so certainly go back and listen to that because I don't think we're gonna touch on that too much in this episode. It might come up, right? But um I imagine everybody and their brother has heard everything they want to hear about uh that herbicide and that type program. But Sarah, what we'll do is we'll start with you and kind of start this conversation around droplet size and nozzle type and sprayer output, and then we'll kind of work our way back over to Charlie.

SPEAKER_00 9:55

Yeah, so I guess when I think about that, you know, kind of my spin on Larry's thing about the most expensive application is one that doesn't work. The least expensive part of that sprayer are the nozzles. I mean, right? It's not a small investment when you're going across 120 feet. But golly, it's a shame to have a herbicide application go sideways on you because of the least expensive part of that um high-tech piece of equipment. So I think choosing the right nozzles is key as we start off this conversation. And Camp, I'm gonna do a little shameless self-promotion here. We actually had Tommy Butts on the Ween Science Podcast, the World Speeds podcast. Um that episode actually came out, I think, last week. And Tommy did a pretty good job of going over kind of nozzle selection and things like that, and just you know, making sure that you're picking that kind of course, medium to coarse droplet size for your post applications and and making sure that you actually are using the right orifice size for your sprayer speed. Um, I think a lot of times we just take what the dealer sends us or what we get on the machine and we just roll with it instead of taking the time to actually do the math and figure out, you know, what size nozzles do we actually need on that machine?

SPEAKER_03 11:07

Yeah, and I I actually got a uh a used machine to use for plot maintenance and stuff this year. And uh I went and bought some nozzles and all that good stuff. And come to the rate controller's a great piece on that machine. But man, if you are we had some red ones, so I guess those are 04s, but we were going and in those machines, and I'm sure y'all know you can fly, like you can really move with those things, but you start going much over seven or eight miles an hour with some 04 nozzles, then you're going at 70, 80 psi, and you're you're losing a lot of the benefit of some of those coarser droplets, right? Because it's upping the pressure, you're getting a lot of fines, and and those things can potentially go places where they don't need to be. And so we need to uh certainly if you're if you intend to drive that fast, uh, that's something to take into consideration. But I honed in my speed and and we're at seven or eight miles an hour, which it feels really slow in one of those things. I don't know if y'all have driven one, but it feels really, really slow. So um what about what about sprayer output in terms of you know, do you recommend it? I know that some of the labels say 15 gallons. I I didn't know if y'all had a recommendation, and and I know that guys are trying to cover as many acres as possible, but what what's kind of your thought on something like that?

SPEAKER_00 12:33

Yeah, as we think about, you know, post applications and the role of glufacinate um in our cotton acres here. I think 20, 20 gallons is a great idea. Especially like you said, we're driving faster and we're kind of pushing the boundaries on some of our other parameters. And I'm not saying that that extra, you know, to go from like a 15 to 20, it's not gonna like cover all your sins, but I think it can can take an application that at 15 or 12 GPA might have been a little questionable, and it can kind of turn it around. I mean, sometimes in our plots, we have trouble separating 15 and 20 GPA, if I'm being perfectly honest, but we are spraying, you know, 20 inches above the canopy, we're walking three miles an hour, we I mean, we're dialed in, right? So I think that's where the big difference lies.

SPEAKER_03 13:24

Yeah, for sure. And you know, whenever you're doing everything right, you know, 15 to 20 doesn't seem like much, but for sure, you know, it's I worked for Dr. Culpepper and Dr. Prosco from during my graduate school, and and Dr. Prosco always says, he's like, Man, I'm doing research wrong. Like, I measure everything before I get in the field and all this good stuff. And he says, I need to do it wrong because those are the calls you get, right? The ones that don't go right. And so certainly a lot of good stuff there. Dr. Steckle, what what about on your end in terms of droplet size and nozzles and and sprayer output and different things like that? What are some of the some of the considerations that you're uh helping your guys out with?

SPEAKER_01 14:09

Well, just kind of along the lines of Sarah, uh, you know, 15 typically with most of our applications is is going to be better, more consistent than 10. Um, but then I start getting some practicalities, you know, the research we do and all, but you know, some of the farmers, and I've talked to them about going up to 20, and and you know, I think they get a little better control, particularly if they're borderline too big on some weeds. Uh, but you know, that's another five gallons an acre. And somebody that's spraying 2,000 acres of crop, that's that's 10,000 gallons of water they gotta haul. Uh, and that's uh quite a few tractor trailer loads and and and logistics of that. I always had to get pushback on that. The logistics of that when they're when they're trying to manage a lot of weeds over a lot of acres over counties can be almost unbearable. And that's that's the pushback. And and I have to always kind of think about that when I'm telling them to do 20 over 15, because um as you all know, especially if you look at the Dicamba label, in a lot of hours in the day, you can actually spray that thing and be on label. Uh and so if you're filling up a thousand-gallon spray tank, that can take some time. So it's there's a lot of you know, give and take on on you know that extra five gallons of the acre. I think sometimes it can be a big benefit, but depending on your logistics, it it may not be doable.

SPEAKER_03 15:27

I'm I'm impressed that you're even having a conversation, Sarah, with your guys about going from 15 to 20, because most most of the ones I feel like I have are more around, hey, let's go from 10 to 15. Five. Yeah, yeah. Or like seven to ten, right?

SPEAKER_00 15:43

So so to Larry's point, yes, the logistics trump agronomics every day of the week, right?

SPEAKER_04 15:50

Yeah.

SPEAKER_00 15:50

But to your point, Camp, I think I've got a lot of guys who are used to spraying paraglat and they know they need coverage with things like cont you know, contact herbicides like that, like uh Grmox and things of that nature. And so they've they have seen for themselves in these super dry environments. Like I the guys in western Kansas are just to use a phrase my teenager uses, they're just built different. That's right. The environment that they're in and the things that they have to do to try to try to get things done.

SPEAKER_03 16:23

Yeah, no doubt, no doubt. So, Charlie, what about you? And we can kind of wrap this up and then move on to the next one.

SPEAKER_02 16:31

Yeah, so so yeah, when we when we return to the land humidity and heat, right? We uh we get a little more smooth, we get that glufosinate activity smoothed out a little bit. So yeah, I'm uh I'm uh I try to hit 15 with my guys. Uh and the carrot that I kind of dangle with them is hey, look, look, if the weeds are small, right, 15 is what we need, right? So so catch them small, go with 15, you can get across more acres. You know, obviously when they try to go to to some uh systemic chemistries, they're trying to go down to 10 to cover more acres. But that, you know, I try to, you know, at less catch them small, then you can get across them with 15 GPA and get get consistent control. And now if we get into those marginal situations where they're a little big, 20 definitely helps a lot. So uh that's the kind of the kind of the way I've gone after it is here's the incentive of of getting after the one the weeds when they're smaller, you can cover more acres.

SPEAKER_03 17:28

Yeah, no doubt. These guys are just experts at logistics, they know what it takes. I work with some guys and they do 15 on their herbicides and then they swap to 10 once it comes think bugs and PGRs and stuff like that. So, I mean, they they know how to work these machines and cover the acres that they need to cover when they need to cover them. So,

Time Of Day Changes Results

SPEAKER_03 17:49

so we already touched on this a little bit, but what about time of day? So we talked about liberty, right? And there's certainly a time of day effect with that, but you know, what if somebody, and of course, there's also the legal side of you got to spray from this time to this time with certain herbicides, but you know, sometimes you just got to get it done, right? And so are any advice on on any products that people may see better results from at different times of day, or is it just kind of a blanket, hey, spraying it on these bankers' hours, as Dr. Steckel said, is the best practice for for most herbicide applications. And so we'll start with Charlie and then work our way back.

SPEAKER_02 18:31

Yeah, we've we've hit the nail on the head with Liberty. We've we've kind of uh talked about that a lot, and there was a lot of educational effort going toward getting folks to realize you can't spray early in the morning, late in the evening, right? And those are optimum spray times because we know that the the wind is falling out, right? Um, so obviously folks are thinking about trying to keep this stuff on their their fields, so that's when they might want to do some things, but we can't do that with Liberty. We need, you know, bright sun, as much sun as we can get, warm temperatures, humidity, etc. Now, I will say people have taken that uh and ran with it. And and so we were, in fact, we were planting some corn a couple weeks ago and it was overcast, and we were trying to think about how we're going to burn down some pigweed that was up after we had kind of had a stale seed bed. Um, and I was like, well, it's not a good day to spray Liberty, but let's spray some parakeat. And so oftentimes what folks I'll hear from folks is they'll say, well, it's it's not a lot of sun, so we don't need to spray pariquat, but that's actually opposite of liberty. We we actually get better control with pariquat when we've got limited sunshine, in my experience, because it it lets that that parquat move a little bit more. In fact, I think Dr. York used to say the best time to spray pariquat on some of those marginal weeds like horseweed, etc., was as the sun was going down to give it a little time to move. So I feel like we've done a good job of raising the awareness about time of day with liberty, and and folks need to realize that's not all chemistry, right? It's uh that's a that's a liberty thing now. Some of the other herbicides, a lot of those light-dependent herbicides do need good sunlight, but it's not always the case that we're we're kind of hamstring into those bankers' hours for all chemistries.

SPEAKER_03 20:15

Yeah, for sure. Dr. Steckle, what about you? I mean, same same type of advice on on this time of day type stuff where, you know, with some things it's gonna work better, or just for the most part, we need to be spraying them during normal daylight hours, I guess, is what I'd say.

SPEAKER_01 20:31

Yeah, well, it's kind of like Charlie said, it it's somewhat herbicide dependent in paraphone, you know, you spray in the middle of the day that's really bright and sunshiny. You get that flash burn, and it just doesn't perform as well as it does if you if you spray it on the evening or first thing in the morning. But the HPPDs, uh, those are going to become more and more of a deal in in all our crops. At least some of the early work we're doing, we're seeing a little better control with them sprayed middle of the day. I think that's something we probably, from a research standpoint, need to need to dig into a little more to get it get a handle on it, because uh all we've ever used them for is in corn and you always throw atrazine with it, and atrazine pretty much cleans up all mistakes. So right. We won't have atrazine in cotton, right? So so anyway, it's it won't be there to help prop up uh an HPPD, but uh, I think time of day may also affect that herbicide as well.

SPEAKER_03 21:20

Yeah, yeah. And so for those that I'm sure everybody's aware, right, that the Stoneville and Fibermax varieties have resistance to HPPD herbicides, of course. Uh those chemistries have not been labeled for those varieties yet, but they they are optimistic, right, that that's coming. So um certainly something that we need to be talking about in the future. And and once that gets labeled, I do intend to have an episode on some of that stuff. So so we may be revisiting some of that. But Sarah, what about you in terms of in terms of time of day?

SPEAKER_00 21:55

Yeah, I mean, time of day is another one of those things, you know, Churley and Larry both did a good job of just. Talking about the fact that it is kind of different from herbicide to herbicide. I mean, I have a lot of guys that inversions notwithstanding, gotta say the I word, the D word, so we gotta say the I word.

SPEAKER_04 22:11

Oh, yeah.

SPEAKER_00 22:13

That they try to spray at night because that's their highest humidity. And in a lot of cases, our plants are actually recovering overnight and functioning better than they were during the day when they were baking with low humidity and and high temperatures. And so I think the thing that I try to get folks to think about with all herbicides, right? Glufo liberty included, is that the better the plant is is working, so the better the growing conditions are for the plant, the better that herbicide is going to work.

SPEAKER_04 22:43

Yeah.

SPEAKER_00 22:44

Right. I think that's kind of my my rule of thumb that I try to use when I talk to folks about it.

SPEAKER_03 22:49

You know, the the big one here, obviously, we already mentioned that hey, you got to spray from two hours. What is it? What's the rule? Two hours after sunrise, hour and a half before sunset. Is that the rule for die camera?

SPEAKER_00 23:03

Two and one, but I don't remember which way it is.

SPEAKER_03 23:05

I should know. I don't know. There's some legal stuff with respect to some of these herbicides in terms of time of day, but also with some other chemistries, right? There are optimum times to make those applications. We've we've talked about Liberty a lot. That one seems to be a little more temperamental, whether it's time of day or, you know, having AMS in the tank in our drier environments across the belt. But, you know, one thing that I think is important, and whenever we start talking about optimizing applications, one way that growers look at reducing cost is by reducing the number of trips across the field.

Tank Mix Antagonism And Resistance Reality

SPEAKER_03 23:43

And so if you can throw as many things in the tank as possible, that's what they're going to do, right? And so one thing that comes to mind for me, and I know there's been a lot of work on this in the in the weed science world, is some of this uh antagonism and synergism type interactions between chemistries, maybe even uh interactions with uh herbicides and insecticides and different things like that. So, Sarah, we'll we'll start with you and and kind of start the conversation on this subject. But what what are some of the things that growers need to keep in mind in terms of tank mix partners to optimize that application when they decide to get out in the field?

SPEAKER_00 24:24

Yeah, so thinking from a cotton perspective on this one, Camp, I think you know the big thing is you kind of got to give the the textbook answer here, check the labels.

SPEAKER_03 24:33

Yeah, oh yeah, right.

SPEAKER_00 24:34

I I think the something else to think about is yeah, you can have that physical incompatibility that creates a mess in your spray tank and slows you down and costs you money that way. But also, you know, you can have that that chemical or biochemical incompatibility, right? And the the examples that I have been using in the enlist era um for that antagonism piece is the interplay between the group four herbicides like 240, so enlist and our grass herbicides, so things like lethadem, ashore, or sorry, select ashore, things of that nature. They're kind of the poster kids for how the group four herbicides really decrease that grass control. And so, you know, we talk a lot about the fact that you can overcome it to some extent by increasing rates of your affected herbicide, but the only true way to overcome that antagonism is is to split them out and then circle back to our logistics conversation and how you let into this question. That doesn't always work.

SPEAKER_03 25:34

Right, right. So what about uh potential synergism, right? And I mean, I there may not be as many opportunities for something like that in our over-the-top options, but but I know of a few in terms of burn down and and different stuff like that.

SPEAKER_00 25:52

Yeah, when I think of burn downs, you know, we we look at a lot of paracat products and we like to put some sort of photosystem to inhibitor in with those products. Now that becomes more challenging in the cotton world, right?

SPEAKER_04 26:06

Yeah, right.

SPEAKER_00 26:07

Um, and most of our fellow acres, right, that's either atrazine or metrobusin. So I think that's a little more challenging in the cotton world.

SPEAKER_03 26:14

Yeah. Yeah. We we typically will do grimoxone and diuron, right? And I mean that kind of yeah, that kind of covers your bases there. It does a really good job, can cover a lot of mistakes, you know.

SPEAKER_00 26:26

So do you know how many guys I don't hear talking about things like diarron in Kansas?

SPEAKER_03 26:32

Well, it's probably not very many. We use it, we use it a lot around here, but I know that there's not many people across the belt really that use it like we do. So it is uh I'm I'm pretty sure Stanley uses it in a cereal. Yeah, he might. He might. He recommends it like nobody's business. But um, yeah, so certainly a lot of opportunities there. So, Dr. Steckle, you've kind of got some some interesting stuff going on in Tennessee with some of the pigweed populations you're dealing with. So talking about, you know, optimizing the application with respect to minimizing the number of trips across the field, but also keeping in mind that there could be some antagonism with some different weed species and and different things like that.

SPEAKER_01 27:24

Yeah, it's uh kind of depends on the weed species. Now, like like with Palmer Amaranth, um we've got populations that are still fairly susceptible to the oxen herbicides. Uh, we got some that have fairly low level resistance, you know, about 2x or so. And then we have some that have 10 to 12x dicamba resistance. So and then in some places on top of that, we've got some pretty sketchy liberty control on the same population. So but we find if we mix the two together, whether it's like in list and liberty or dicamba and liberty, we can actually get some fairly decent control if we can do sequential applications back to back about two weeks apart. On the really resistant locations, though, we've actually found that if you split the application up, don't put them in the tank together, and this doesn't help on logistics, but uh you will get better control, is uh run dicamba first and come back with Liberty. It can be a sprayer right running right behind the other one, for that matter. Uh, and we'll improve control about 10 to 15 percent. So uh with that population of pigweed and where it's located, just any port in a storm, uh, you you gotta go there if you're gonna get control. Um on our on our resistant, we got a lot of glyphosate-resistant grass species, most notably one, I think we got it from Charlie in North Carolina, is the ryegrass. Uh, we just we just become a ryegrass nightmare now, I guess like North Carolina's been, but this year's been awful. Uh, but a lot of antagonism with glyphosate and clethodim with the oxen herbicides too. And so we traditionally we always put dicamba in the tank, and that's hurt our ryegrass control. But even on our annual grasses like goose grass and uh barnyard grass, jungle rice, it's glyphosate resistant. You know, we're going with clefidem more and more. If you got dicamba in the tank, uh, or even if you're spraying it a week ahead of time, a lot of times uh you'll see antagonism uh where it's gonna hurt the grass control with glethidem. Um so it's a lot of things to consider when when you're trying to struggle with these resistant species. Um and uh it there's just no way around cost on it. You're just when you start having resistance like we've got, your wind control costs are gonna go up. There's just no other way around it. Yeah.

SPEAKER_03 29:36

That's kind of the nature of the beast, which uh is really unfortunate, but it's the cost of doing business, as they say. So Charlie, what about you? Similar, similar stuff, I assume.

SPEAKER_02 29:47

Yeah, absolutely. We see the the grass antagonism with the with the aukses for sure. I feel like it's a little uh we see it. I feel like I see it a little more with the dicamba than what I see show up with in my tank mixes with 2,4D. So I won't I won't belabor that point because Sarah and Larry did a good job of talking about that. But I will say that we do a we do a lot of Roundup and Liberty tank mixes. And I, you know, I I do it a lot in my own plots. I'm a big fan of it, right? But but folks need to understand that there are there is antagonism with those tank mix. It just most of the time it doesn't show up because we're going after Palmer pigweed. We can't control that with Roundup anyway. Uh so it it's we basically equate it to uh liberty with a little bit better grass control than liberty by itself. And so, but that that antagonism will show up in some on some weeds that we don't normally talk about anymore, like some of the broad leaves that are a little too big, like lamb's quarters, right? That we we normally can get with Roundup. We mix it with Liberty and all of a sudden we didn't kill the lamb's quarters. Or maybe some ragweed that we we still can control with Roundup. If it's too big for Liberty to control by itself, we can it can show up there as well. Uh folks need to understand that there is antagonism with that tank mix, although we use it a lot. Um, they need to think about it as Liberty plus a little bit better grass control, but it's not as good as Roundup on larger broadleaves that are susceptible to Roundup. So that's kind of the rule of thumb that I kind of try to point out to folks. And then also now we're moving to some Liberty grass herbicide or clethodim and uh sure tank mixes type things. Uh so we can also need to understand the same kind of thing there, right? It's it's liberty with a little bit smoother grass control, but it's not gonna be as good a grass control as we would get with those grass herbicides by themselves. Yeah. And I think as long as folks understand that, uh they can figure out how to use it in in their system.

SPEAKER_03 31:50

Yeah, for sure. Now, I'm I'm curious, you know, everybody mentioned some of the auxin herbicides and roundup and and potential antagonism there. In y'all's observations, does the size of the grass matter much, or is it it just across the board?

SPEAKER_02 32:08

Absolutely. I mean, I I think there's a lot of in in in North Carolina, I think there's a lot of things contributing to it. Number one, a lot of times we don't have a residual grass product, right? We might have a residual, maybe we had reflex, maybe we had directs, but we maybe we didn't, we left out to warrant or to prowl. And so we didn't get as good a grass control as we could have up front. Uh then a lot of times we're doing a tank mix of a roundup in Dicamba, a roundup in 2,4D, and that didn't do great on my grass because of the antagonism. And then all of a sudden now I've got foot tall grass out in my field, and folks are are finally realizing that it wasn't controlled. So there's a lot of things at play. Growing conditions, I think when we're, you know, we're hot and dry, it makes it much worse, and the the calls just flood in with antagonism. So I think that's a big part too that we've kind of had to get out ahead of in terms of educating folks about think about this, the growing conditions, like Sarah said, when you're making these applications.

SPEAKER_03 33:11

Yeah, in terms of uptake, like it being so dry and not being able to take up the the stuff.

SPEAKER_02 33:16

Just harder to get in, you know, not growing, not translocated as well. Yeah.

SPEAKER_00 33:22

And I would almost take the other side, Charlie, in that I get a lot of calls on sorry grass control, particularly cover crop burndowns, when it's the beginning of April and it's 70 degrees one day and 40 the next five days, and they're trying to spray these, you know, uh select or roundup types of products, and it's just too cold. Um, the plants aren't kind of working well enough. And so when we throw our 240 and our dicamba in there with it, we just see less than desirable grass control.

SPEAKER_03 33:55

Yeah, for sure.

Overlay Residuals And Manage Injury Risk

SPEAKER_03 33:57

So, you know, we talked about overlaying residuals and and stuff like that. But man, one one thing we hadn't touched on much is the best thing you can do is be out there looking, right? And so especially in the situation that Charlie talked about where they they've been really dry and uh maybe didn't get stuff activated when they need to. And so making sure that we're timely with all these applications. And we did kind of touch on some of that just a second ago with making sure that you know you start to see some of those reduced efficacy type effects whenever the weeds get too big, right? And so we want to be timely with all this stuff, but certainly part of that is uh overlaying residuals. And uh, you know, I know that there aren't people, a ton of people running lay-by rigs anymore. I mentioned before the podcast started I run one just because I guess I like to drive slow. But um, you know, at the end of the day, we don't have a ton of residual options, um, but kind of want to talk about the residual options we do have, maybe what road to go down with some of those, and then balancing in herbicide injury with yield potential and weed control and different stuff like that. And so we'll start with Charlie and then work our way back uh to Sarah over there in Kansas.

SPEAKER_02 35:18

Yeah, so I mean, cotton is cotton's a really cool crop. You can you can at the beginning of the year, you can kind of set a calendar for weed control. You know, if I get my pre-activated, you know, I probably need to be spraying my first post eight, and this is specifically for Palmer, and that's it's kind of driving everything now. But yeah, you know, if if I get my pre-activated 18 to 21 days, I probably need to be spraying my first post. And then two weeks later, my second post. And then two weeks later, um, you know, hopefully you still got a lay-by-rig and you can do that, but a lot of times now it's it's another post over the top application. My worry is that you you mentioned it earlier, our residual options are few and far between. We're we're essentially down to the group 15s, uh, and we are just wearing out that chemistry. We've recently identified some group 15 resistance in some of our grass species over this way. So it's it's a matter of time before we just completely break it. So yeah, but but that's kind of until we get some newer chemistries, like maybe the HPPDs, they might have an over-the-top residual option in the future uh with the the accent cox and cotton that might be coming. Yeah, that the group 15s is where we're at. And and I I'm a big proponent of lay buys. Um I I talk about it. Folks don't want to hear it. There we do have a few people that still run them, but I would love to get you know another residual option like some diuron in there at the end of the season uh to kind of finish out the crop. It it has a lot of uh potential and and can protect us from some resistance to these over-the-top products.

SPEAKER_03 36:55

Yeah. And I, you know, whenever we run ours, we're running Roundup Diaron Invoke, something like that, you know, trying to clean up whatever's down there. Nut's edge, morning glory is the whole deal. I mean, you can really tailor a lay-by application to whatever your problem is and fix a lot of heartburn for the next year, the end of that year and the next year, right? So um certainly could do a lot of good. Now, uh in Georgia, Charlie, our guys really do not like herbicide injury. So are y'all in the same boat? Y'all, y'all don't like it? Are y'all good with a little bit? Or, you know, how do you balance including some of those? And uh, have you ever seen, I guess, reduced yield from including some of those over-the-top type residual products? Or uh what what do you think?

SPEAKER_02 37:42

Yeah, so no cotton farmer wants to see injury, right? That's uh a kind of a carryover from from Roundup resistant cotton, where we could have clean cotton with no herbicide injury, right? Uh so we still buy to that. Some some are more open to it than others, right? Some know that cotton is resilient. I I was I will say, you know, I have to go back to the old wide-strike cotton to find some data where we could actually get a yield loss from some of these tank mixes. Now, again, uh we know that the the group 15s, in my opinion, are the culprit. The growing conditions or the moisture at application are a big culprit. And if we get injury, and then uh, in my opinion, a lot of the issues stem from these elaborate tank mixes. I got an insecticide that's an EC, uh, and then I put Hellfire adjuvant in there with it, and I don't really know what's in Hellfire, but I was told to use it. Um, and it it's got an oil in it too, and then I've got a loaded roundup, um, and I've got Liberty in there that's got a lot of adjuvant in it, and then I got a group 15, uh, which may or may not be oil-based. And if the cotton's real tender, we're gonna burn the snot out of it. But I will say, I, you know, it's really hard to get a crop response or get a yield response, um, even with some of these elaborate tank mixes where we just burn the snot out of the cotton.

SPEAKER_03 39:03

Yeah. I I work really close with our entomologist, and he, of course, I already mentioned I worked in weed science on my PhD, but I I ain't scared, you know, to go out and spray some stuff and ding it up a little bit, and he hates it, right? And so I we've got a field that's got uh Bengal Dayflower or tropical spider wort real bad, and it's like every five days from the about two weeks after it comes out the ground, every five days we're doing something. So I'll go out with Roundup Staple and five days later, round or Liberty and Duel, and then come back about a week later and hit it again with something else. And he's like, Man, you're gonna kill it. But it it always does good, you know. And sometimes we'll have orthane in the tank for thrips and different stuff like that. So it's uh, you know, it's certainly a game you gotta play, especially if you got uh weed like that, that's a huge issue. But but yeah, nobody likes it. Nobody likes to look at it. It's not any fun. So, Doc, Dr. Steckle, what about you in terms of uh some of the residual options that you guys are and maybe even some of the uh application timings or or intervals, right? If y'all are making sequential applications of some of these group fours and Liberty and stuff like that, are you putting uh uh group 15 in there back to back? Or, you know, would you are you doing it every seven days or 14, or kind of what's the situation up there?

SPEAKER_01 40:25

Well, we're we're really getting it's got probably 70% of our acres are better now getting peroxisulfoam put on, either residual or anthem, um, with fertilizer. And that's really, really caught on. And you don't see any injury with it at all. So that's that's one of the big pushes with it. Plus, it's just it's been the most consistent way in my experience to to get a residual to activate it. That perhaps a cell phone doesn't need a lot of water to get activated. And it seems like we've done it with irrigation, without irrigation, uh we used it on tens of thousands of acres in the state, and uh it pretty much always gets activated. I don't can't think of a time where it didn't. I think it even on you know, just pulling the humidity out of the air and those that fertilizer melting into the soil, I think it pulls the herbicide in with it. It it seems to be a more consistent way to do it, and uh and then logistically it it really helps because you're not tying up the sprayer, fertilizer guy can put it out. So there's a lot of pluses to it, and it's really caught on in Tennessee. Um, just because of all the pluses. Of course, the negative is a little more pricey than what you're gonna get with a dual or a warrant, but it's it's really caught on. And uh and it's really, I think, really helped us on our our control because you know it you can put it on about that five leaf. So that's about the time that pre is given out. And uh it really gets you to where like we do have a few folks that use lay-by rigs or hoods, so it can get you to those uh in in a lot of cases.

SPEAKER_03 41:55

So if you got a few guys running hoods, like what are y'all what are y'all running under your hoods that that seem to be working well?

SPEAKER_01 42:03

Uh well, there's a little good bit of peroxisolph on you then too, but that's and it may not be as much this way. But a lot of that like you all are doing, diuron in SMA. A lot of liberty. Some of the you know, more robust things would be like liberty and zidua, something like that. There's a good bit of some of that that goes out, but and that'd take you home, uh, typically when you get that kind of residual on there. And it's the struggle we're having trying to control a lot of these weeds post, the best way to control them is to keep them from ever coming out of the ground. So overlaying residuals and and to me, peroxisophone really is it's it's a it's a game changer as far as managing these weeds that we're really struggling to control with any of our post-herbicides, whether it's grass or broadleaves. Yeah.

SPEAKER_03 42:48

Well, and the logistics piece is a big, big part of that, and we've talked about that a lot in the last 45 minutes. But I mean, you know, these guys, they they're trying to cover as many acres as possible. And if you can cut a cut a trip with a sprayer and just add something in to a fertilizer application or whatever, I mean, that's a that is a game changer in and of itself, right? So certainly helpful uh from that front. So uh Sarah, what about you in Kansas and out west uh talking about some of the residual options and then balancing some of this injury and weed control and uh yield potential and and even you know, in your neck of the woods, potential delays in maturity, if y'all see much of that.

SPEAKER_00 43:30

Yeah, so the delay in maturity can be a big thing. And you know, you set cotton back with something, you know, Charlie was talking about the super hot EC formulations with an EC insecticide with some super duper gonna kill the weeds because they're drought stress adjuvant package. I mean, you can set the cotton back. Um, we did some some on farm work um this year and we saw saw some differences um in maturity because of that. Um, I was glad Larry mentioned the zidua on the fertilizer. Thing. It hasn't really taken off here in Kansas, but I know that our friends kind of further west and the Texas panhandle, I know they love it for all the reasons that Larry was talking about. I think that's their their go-to. For us here, okay, don't you guys are gonna think I'm crazy when I say this, but sometimes our cotton never actually closes throws, right? We're so far north and we're so dry. We're growing stripper cotton for the most part. Um, so we have so what guys usually do is there's no group 15 in front of the planter, usually. And so we're coming back usually with a couple passes of aceticlore is probably the most common that folks are using here in that second and third trip um across the field.

SPEAKER_03 44:45

Yeah. So yeah, for sure. I mean, we we tend to use a lot of that or dual or you know, whatever it is, but it's it's kind of like we talked about. I mean, it's the cost of doing business and and you know, just knowing those products and knowing what they can do. I've walked into fields that have been sprayed with some of that. It and at first bloom, somebody says, Well, man, I'm missing some first positions out here. What's the what's the deal? And I'm like, Well, did you spray this, you know, about two weeks ago? He said, Yeah. I said, Well, that it shucked that first position, right, because because of a little bit of injury. But at the end of the day, cotton is such a it it compensates so well, right? That it in the environments that you can afford to compensate, Sarah. Uh, you know, you you can afford a little mistake like that. But man, in in a place like Kansas where you just do not have time, you cannot afford one of those mistakes.

SPEAKER_04 45:39

So all right.

SPEAKER_03 45:40

Well, that

Ryegrass Plans For The Next Season

SPEAKER_03 45:41

was anything else that y'all wanted to touch on.

SPEAKER_02 45:44

Larry mentioned something about ryegrass and and the the ryegrass problem, people need to be thinking about ryegrass management for this fall right now. Yeah. Um, but I because you you need to remember the spots that are terrible right now and make a mental note of them and hey, let's let's get out ahead of it. Uh whether we plant a cover crop like cereal rye, or we do a fall residual, or we do both, or we say, hey, we know where we got a bad ryegrass problem, we're gonna be out there sooner in the spring instead of letting it, you know, get all the way, grow all the way to planting. Um, let's think about that right now and and make mental notes so we can do a little bit better job going into our our next cropping season.

SPEAKER_03 46:27

Does the rye choke it out, Charlie, or how does that how does that work? Because I know I heard Stanley talk about how on their place up there they planted wheat and then sprayed sideline on the wheat as their cover to prevent the ryegrass from being a problem. But on rye, you can't do that. And so, or you I guess you can, but you'll see a lot of a lot of injury in the rye and stuff like that.

SPEAKER_02 46:51

So Yeah, so we we've done a we've done some studies and and what was when we initially went into it, we thought the cover crop was just going to be for erosion, you know, control stability. Uh, and we did fall residuals too, coupled with the the cereal rye. Uh, but the the year that we in one year of the study we got six to eight thousand pounds of biomass, and that's kind of what the the point that we we talk about we need for palmer suppression in the summer. And that year, the the residual herbicide didn't didn't mean anything. The the cover crop controlled the ryegrass um by its as well as the cover crop plus the herbicides. Now the next year our cover crop got cut in half, about three to four thousand pounds, and that was that year we needed the residual herbicide in the fall. So it's kind of a a multi-tactic thing, right? You know, integrated weed control. We got to do both. Um, but the rye, the rye surprised us a lot. Something that we thought was gonna just be for erosion stability, ended up that competition, that allelopathy, etc., showed up in that first year of that study as having a major effect on suppressing that ryegrass. Um, it's just, you know, if you if you leave any open space out there, it's gonna be invaded by ryegrass. So we're we're basically trying to replace a species we can't control with herbicides with something that we can. Um and that, you know, that's catching on. Uh also one of the things that our growers have really taken to heart is not letting it go to seed. We had, you know, you know, we had some folks that have been, you know, they'll spread a uh winter grass out there and then they'll they'll cut it and for and bale it for hay. And you know, I'm fine with that as long as the ryegrass is not going to seed, and and they're scalping it really, and they're telling me, hey, I've been doing this for two years and and the ryegrass is getting beat back. So uh as long as we're not letting that stuff go to seed, however we accomplish that, we need to be diligent in trying to keep it from going to seed.

SPEAKER_03 48:51

Yeah, for sure. We we've got a little spot here on the station that we grow some seed rye, and it it was amazing to me that in the little triangles where the where the grain drill didn't hit, it was 100% ryegrass. And so I had to go around in February and spray a lot of those edges just to make sure that the seed the ryegrass seed was not going to get into our rye uh rye crop. So certainly something now, whenever you talk about fall residual herbicides, are you talking about spraying something after the cotton's defoliated before the rye is planted or or what what's kind of the the program with something like that?

SPEAKER_02 49:32

Well, I mean, I I don't Larry and and Sarah uh can chime in on this as well, but you know, we talk used to think about ryegrass being, you know, and I still think a bulk a lot of it comes up in October. But we're I'm getting pictures in September of ryegrass coming up. So um with our bean crop, uh our full season beans and our cotton, a lot of times the ryegrass is there after we harvest. So corn acres is a big opportunity to to do something in the fall. Uh if if we do have want to do a fall residual behind soybeans or cotton, obviously we probably got some ryegrass up that we need to try to kill with something, right? A lot of times that's going to be paraquat or clethodim or something like that, because Roundup is uh not working in a lot of areas. So uh just need to be cognizant of that. It's not just a fall residual. A lot of times, if you're doing it in November or early December, it's you probably got a crop of ryegrass that's already up. Yeah.

SPEAKER_03 50:32

For sure. Doc Dr. Steckle, what about in your neck of the woods? And and I know that, you know, once you get on the on the west side of the river for sure, they're doing a lot of tillage and and bedding and stuff like that, and and maybe applying residuals after that. But uh, what are y'all doing in in Tennessee to kind of get ready for what would be 2027 with respect to fighting some of this ryegrass?

SPEAKER_01 50:56

Well, uh, we're not doing a very good job. It's like we did this past year. We need a better weed scientist in the state. I think that's pretty clear, but um I it's been a struggle. Uh it's it's I've never seen it's never been as bad as it is this year. Uh it's across the whole state. It's it's just it's been nothing but calls on it in every crop. So that's one thing different than you know, like pigweed, which it's more of a problem in our in our broadleaf crops. Uh ryegrass isn't it's in weed, it's in it's a problem in corn, cotton, soybeans, it's in everything. So it you gotta think about it in everything. We've been really looking at the falloppied stuff. Uh, we don't kill, so that that really kind of limits us on what what we can and can't use and and what will work well. And I think on some of our bad fields now, this this this week's got enough focused attention that I think we're gonna start seeing some falloppied stuff go out. Um but one thing that's been interesting to me is you can do a good job in the fall on it. But we we clearly in in a number of these fields get a spring flush as well that if you you kind of fall asleep on, you'll it'll it'll come up and get you. So you gotta stay persistent on it throughout the the winter months. Uh fall and spring. So yeah, do a lot of stuff that you're only saying, uh trying to deal with something, get the fall applied on it. You know, it's the falls are usually pretty dry here, so herbicides that don't need a lot of water to get activated have been the ones that have performed the better for us, or something like command, uh, which it it needs water to get activated, but boy, you'll reach back and get ryegrass once you finally do get a rain, even stuff that's fairly well established. So we're we're looking at a lot of falliplied stuff and then and then being watchful for it in the spring, uh getting another flood.

SPEAKER_03 52:46

Sarah, what about you?

SPEAKER_00 52:49

So we've only got about a handful of counties in the very southeast corner of the state where they're starting to call me about rye grass problems. So we're collecting some seed this fall or this summer rather, um, and we're gonna try to screen it this fall. They're worried about Axiol and they're worried about Zidua. We don't know if it's just the hit they missed the timing on that fall Sidua application, um, or if it's really something going on there in terms of resistance. But we're yeah, it's just in there's about half a dozen counties in the very southeast corner of the state, which are not cotton counties, right? They're mostly fighting it in wheat.

SPEAKER_04 53:26

Yeah.

SPEAKER_00 53:26

And that part of the state also, the the guys both said tillage, they're pretty heavy tillage in front of their corn and beans. And so wheat is really the only place where we're fighting that one in Kansas.

SPEAKER_03 53:36

Yeah.

SPEAKER_00 53:37

And I hope hope it stays down there.

SPEAKER_03 53:39

Yeah, no kidding. No kidding. And that's you know, you mentioned one thing that I feel like has worked for us in in Georgia with respect to ryegrass. They Dr. Prosco and and Dr. Culpepper both talked about it this winter, I know, but with peanuts, we still break a lot of ground, you know, and so bury some of that seed, and it it doesn't do very well. But uh it started, it it ramped up out here this year for sure. So certainly an issue that everybody in the cotton world needs to be aware of. So

Final Takeaways And Thanks

SPEAKER_03 54:10

uh good discussion again, optimizing uh some of our weed management tactics, herbicide applications, stuff like that, and even looking to 2027 in terms of being timely with some of this stuff that we're doing after the cotton's harvested, getting ready for the next crop. So, certainly want to thank Dr. Charlie Cahoon, Dr. Sarah Gansky, and Dr. Larry Steckel for joining us today. And uh certainly also want to thank Cotton Incorporated for the sponsorship of this effort. And if y'all have any questions, please don't hesitate to reach out.

Outro Music

SPEAKER_05 54:41

Well, you take all my money, you take all my pride, you take up all my time, and then you take me for the ride. I got cotton picking, cotton picking, cotton growing blue, I can't live without you, but living with you make a man for two Well it first you grow so slowly, but I can't make it stop where we're without it, and I'm out of the big I can take it, I can go and I did all my day. You can go to the case, it's still the only two Well if it was the call you call me, you promised me the moon, and then I wish I wasn't both I got I can take it, I didn't take it, I didn't grow it But I can't live without it Living with it water gonna do one rain away from glory, but it's still the only life I'd choose. Well I finally made some money, it's the cotton picking cotton grooving blue.