Arkansas Row Crops Radio

Weeds AR Wild Series, S2 Ep12. Wet and Rainy Weed Control

May 04, 2022 University of Arkansas System Division of Agriculture
Arkansas Row Crops Radio
Weeds AR Wild Series, S2 Ep12. Wet and Rainy Weed Control
Show Notes Transcript

Weeds AR Wild Series, S2 Ep12. In this week’s episode, Extension Weed Scientists Drs. Tommy Butts and Tom Barber discuss how the wet and rainy weather is affecting weed control and some current questions that have been coming in.

Weeds AR Wild Series, Season 2 Episode 12. 
Title: Weeds AR Wild Series, S2 Ep12. Wet and Rainy Weed Control
Date:  May 4, 2022

[Music]:  Arkansas Row Crops Radio providing up to date information and timely recommendations on row crop production in Arkansas.

Tommy: Welcome to the Weeds AR Wild podcast series as a part of Arkansas Row Crop Radio. My name is Tommy Butts, Extension Weed Scientist for the University of Arkansas System Division of Agriculture. And today, Dr. Tom Barber is joining me. We're going to have an Extension weed scientist talk with Arkansas, I guess, today. So, Tom, you want to say hi to everybody out there.

Tom: Hey, what's up out there in podcast land? [laughter] Just happy to be here since we can't plant anything. We're just talking to ourselves.

Tommy: Yeah. I haven't looked outside yet, but it's fixin to start raining again here. So, great news for everybody, apparently. Basically, in today's episode, that's pretty much the main hot topic that we wanted to talk about – is weed control in the wet and rainy weather we have right now. And so, we're going to try and cover a few hot topic questions we've been getting. And then just a few of our recommendations with all of this. Like I said, this wet weather and what we need to kind of be doing to maximize our weed control at this time. So really the first thing that we wanted to jump into because of the really the weird, strange weather we've had, it's been cool. It's been very wet. And really, it's resulted in a very extended window or at least multiple flushes of some of these winter annual junk weeds that we're dealing with. And there's a variety of those weeds. And we're getting pictures every day of different weeds and, “What weed is this?” and “Why can't we kill it?” and those kinds of things. So we just kind of want to chat about that a little bit. One of the first questions I've gotten too is, this late in the season and trying to plant as fast as we can – “Should we even be applying herbicides at all, or should we just be trying to till it up? What's our best option here?” And Tom, I don't know about you, but at least my recommendation has been, herbicide is going to help, because if we just trying to kill it, we're going to end up with a bunch of clumps. We're not going to have a nice seed bed to plant into. It just leads us into more problems if we don't at least try and apply something ahead of time. So what are your thoughts on that, Tom?

Tom: No, I agree. You know, and it's a hard call because herbicides are so expensive this year and everything's expensive. Fuel to put them out. You know, our applications are going to cost us more. So, a lot of people think it's a wasted expense just because we're going to go in there and till it. But you know, as big or as large as some of these winter annuals are now, as big of a root system, like you mentioned that they have. If we just go in there and even if we do invert them, we're getting rain so frequently now, they could just take back root and start growing again. And so it's going to be hard in our current weather pattern, I think, to kill a lot of this winter vegetation and at least plant timely – if we don't come back or go ahead and spray it before we hit it with the tillage equipment. And so that's what I've been telling them too. It's hard right now to talk anybody into tilling because we're so late in our planting window. And so, we're sitting here first week of May and there's a lot of rice, a lot of corn, a lot of beans that are still in the seed sack. And so, in these times, everybody feels rushed to get the planter in the field. You know, one thing we really don't want to do though, is we can't let that crop get up at least before we go out there with our burndown herbicide because there's a lot of these winter weeds that are going to be very tough to kill with our in-crop herbicides.

Tommy: Yeah, that's 100% right. We get into these terrible weather conditions like this, and we all want to be in a rush to get everything planted and in the ground. But we can't forget that we still need to start clean. We still need to get residuals out and make sure that we're getting that out. And so, basically, like Tom was saying there, let's not plant too far ahead of our sprayer. Let's make sure we still get our sprayers across acres. We're getting seed in the ground too, so we might get the seed the ground, but if we don't get our weed control down, we're going to be at a loss too at the end of the year still as well. Tom, just a couple of questions, I guess. What are the main couple of weeds that you're really getting calls on this late in the year now that are problematic? And what's really been your herbicide recommendation for battling some of these fronts that we're at this point?

Tom: Well, you know, and there's a lot of them out there, like we said, and it's really going to be crop specific on what we can do with some of these. But the top two that I get calls on relentlessly are ryegrass and horseweed or marestail. And so, you know with the ryegrass, there's not a whole lot we can do right now other than to go out with an application of Gramoxone at this point or Paraquat or something with Paraquat in it. And it's usually going to take a couple of applications to knock these big ryegrass plants down. So, if you haven't started on your ryegrass, we need to get going on that ASAP. And again, the name of the game now is just burning it down as best as we can because at this point, we've kind of lost that battle. Select, in my opinion, or Clethodim at this point, really does absolutely nothing for us, as large as the ryegrass is. Once that plant starts jointing, the effectiveness of Select goes down pretty substantially and its ability to kill it. And so we're at a Paraquat window on that. Any time, and we mentioned several times on these podcasts, putting a PSII inhibitor with that Paraquat or whether it's Metribuzin if we’re planting corn and beans, or if it's Diuron if we're going to cotton, or Cotoran if we're going to cotton. Rice is the one we really don't have a good, good option to put one in there. I think in an earlier podcast we mentioned Propanil, maybe a quart of Propanil in there, but we've gone back and looked at our plots and that really didn't bring much to the table for us. So, I guess that's not really going to be a good option our rice acres. So, Gramoxone or Paraquat alone is really going to be the option there. And bump that right up as much as we can stand it. The other big one is horseweed or marestail, and it's one that's really going to get some size on it this time of year when these temperatures start going. And we've got corn up with horseweed in it. We've got beans up with horseweed in it. Shouldn't have much cotton up, because I don't know many people that has planted a lot of cotton yet or been able to. But if we don't have anything planted, Dicamba is still a good option for marestail or horseweed control, especially at the rates we can use it in Xtend crops with that 22 ounces of XtendiMax or 12.8 of Engenia. But since we're past April 15th, we're not able to tank mix glyphosate with that application. And so knowing that, that means we're back into a two application window, or we can put Gramoxone in there if our crop is not up – or Paraquat formulations. And so, just check the website for those tank mix options. Dicamba is going to be an option there. Elevore is a good option for marestail or horseweed, but it's basically 14 days I think replant to most of our crops, and so again, that may take us out of a window where we can use that, since we're wanting to plant or may have already planted. If the crops aren't up and then we're planting beans or corn, glyphosate plus 5 ounces of Verdict prior to planting beans or up to 10 ounces of Verdict prior to planting corn is an excellent option for just about any winter annual that we have, including horseweed. Now that's not going to take out our ryegrass clumps, but most of our broadleaf junk – poa annua, mayweed. It'll burn back, might not kill mayweed. We might need a little first shot in that mix for mayweed, to get the mayweed out of there. But the glyphosate plus Verdict is one of my favorite go to burndowns for beans or corn, especially if we know we're in a tight planting window. The other thing that gets used a lot – now this year is a different story, just again, back to price. But a quart of PowerMax and a quart of glufosinate, Liberty, is a pretty good hot burndown on just about everything. Again, excluding the ryegrass. And we can plant anything immediately. And so, other than expense, that's a pretty good option. Only thing that's going to hurt is likely the checkbook. And so, Tommy, the one thing that I keep thinking of when I'm mentioning these burndown options, and I know everybody's in a tight window to move, are these neighboring crops and what we've got planted. So what have you been hearing on that? Have we got a lot of drift calls coming in? – I guess this is the question I would ask.

Tommy: Yeah. Well, so that's good. That's a great question. Because I've been in the same boat. You get all these late applications of burndown herbicides going. And kind of in the same aspect, everybody's in a rush to plant and kind of not focusing on what's right next-door. I've had several calls, too. “Well, we've got rice and corn planted next to each other. Now, what can we spray if we're going to drift, that's not going to hurt?” You know, it's kind of like a pre-planting where the drift hasn't occurred yet. But when it occurs what's going to hurt and what kind of damage can we expect? – basically, is some of the conversations I've had. And so, there's a lot of different calls. You mentioned the Select front. We're trying not to get away from that because it's so late, but we know there's still applications going out there. Drift rates of that onto our corn acres, if the corn is up a little bit, is not good. We still got a lot of wheat across the countryside, which most of that is trying to head and everything else. So we're hopefully out of the window where a lot of that's going to damage our wheat. But there's still a chance that there's some acres out there where that could get banged up from some of this. You know, there's still a lot of issues there. In the corn and in rice incidents, I mentioned that Facet is really quite dangerous for our corn, especially if the corn is up. And that's one that kind of confuses everybody. Because, Facet you can spray over the top of milo, and it's fine, but it will it will bang up your corn pretty good. So watching out for drift of Facet onto corn is a pretty big deal. Command will bleach it a little bit, but as long as it's a drift rate, you can kind of get away with it potentially. Things like that. So just be aware that a lot of our rice herbicides are going to bang up corn pretty good and vice versa, honestly. So we really just need to pay attention to what's around us. Try and be good neighbors. I know it's challenging. We all get in this rush and we're running and gunning, but basically try and just know what's around us and be good neighbors. Tom, you heard other things other than those ones mentioned?

Tom: Now, I think that's the, you know, a lot of Select pictures coming in on corn. I fully expect to see some more. I just got through talking about the Paraquat plus PSII inhibitor mixes. And although they are very good on weed control, when they drift, they're going to be a little worse on our neighboring crops than just Paraquat alone. And so I walked a lot of acres I know, Tommy, last year – rice, beans, corn that had the Paraquat plus the PSII drift on it.

Tommy: I walked a wheat field this year with that on it too.

Tom: Oh really? Yeah. And so I think, we're not able to prevent all the drift occurrences. I mean, we know it's just part of farming and farming turnrow to turnrow with somebody. But you know, the best way we can live with that is just kind of watch the wind the best we can and maybe choose not to spray all the way next to the to the field next-door until we have a good wind to do that, I guess.

Tommy: And have conversations with all our neighbors so that we know. That crop might not be up yet, but it may be planted or they may be fixing the plant in the next week when the weather actually does dry up. And so we could spray something and the residual ends up hurting us. So just have those conversations in advance, so we all kind of are aware of what's going around everywhere. The other thing that we wanted to mention along with that, too, is just for your knowledge. I don't know if everyone knows that this table is in the MP 44. If you check out, it's actually on page 28 of this year's version, the 2022 version of the MP 44. There's a table in there called Sensitivity of Major Field Crops to Commonly Applied Herbicides, and it gives a good little rundown of a wide range of herbicides and the sensitivity of each one of our major crops to that specific herbicide. So that's a nifty little table to kind of give you some quick and dirty information on what some of those herbicides might do to a specific crop. That's not an end-all be-all table by any means, but at least would give you a rough idea of what might happen.

Tom: So, those are always my most uncomfortable conversations when I answer the phone and some of the first things we talk about is, “what will happen if I spray this next to this?” Because it's almost a permission to drill. “Will this hurt my corn if I spray this?” But, you know, it's again, it's part of farming row to row. And we live with it every year. We usually do a pretty good job overall. But, understand a lot of the things that we're spraying now to get some of these larger winter annuals out of the field are going to be fairly detrimental to any crop next-door, I guess.

Tommy: And because of the everything getting delayed, we're fixing to have a lot of different crops going at the same time. There's going to be a lot of different herbicides getting flung out all at the same time, which just leads to more potential injury as well. And with the weather we've had, there's real small windows to plant, but there's also real small windows to get all of our herbicides applied as well. So it's just going to be a lot flying around all at once. We just kind of need to all take care and all work together at this year, because it's going to be a tough situation for everyone involved. And speaking of those tight windows, I guess for our herbicide applications too, something else that's really giving us troubles. Again, with the wet and rainy conditions is that, applying residuals or applying a lot of our herbicides to saturated ground conditions or even standing water really is not a good viable option for us either. And for really several different reasons. One, you know, most herbicide labels tell us to not be applying those herbicides into standing water or into like fully saturated conditions. And outside of just following the label, there's really reasons we don't want to be doing it any way too including basically off-target movement of those herbicides. A lot of our herbicides are water-soluble. So, for spraying them into standing water, wherever that water rolls, that herbicide is probably moving with it, and could damage stuff, basically, downstream. And on top of that, if that herbicide is moving in that water, well, it's not sitting in your soil doing what you need it to do. Right? It's not giving you your weed control efforts as well. So, you're probably having a loss in weed control, a loss in residual length, both because of off target movement, but also the dilution effect – right? Instead of being at our 10-gallon per acre rate that we applied, we just sprayed it in the water and now it's diluted way down. And so we're not going to get the same activity for a lot of those herbicides either. In contrast to that, there's also some herbicides where we can get the exact opposite effect. We've had cool conditions. So, if we have gotten crop in the ground, it's not really growing quickly. It's just kind of sitting there, maybe growing real slow. If you got the wet conditions, it's still trying to suck up some of that water. You get some of those herbicides out there and it sucks up that herbicide. Plus, it's not really growing very quick. It can't metabolize the herbicide very well, and we're going to end up with more crop injury. So, I'm thinking of things like I know on the rice side, Bolero is one of those big ones that if the rice is growing real slow, you get it sprayed out there and it sucks up a big bunch of that. You can get some injury from that. On the soybean front, a lot of our PPOs can cause a lot of heavy injury in these cool wet conditions. You know, there's different herbicides. Tom, on the cotton front, I'm sure there's several there too.

Tom: Yeah. You know, cotton comes up looking for a place to die [laughter]. So, we need the temperatures to help us a little bit on getting our cotton up and out of the ground and at a good start. But, I'm thinking corn, because go back to some of these corn pictures. A lot of them are just the injury from the herbicide application that was made. A prime example of this, if we look at Halex GT, has been a pretty common herbicide program in corn for a long period of time. Well, that's three herbicides, plus most folks – and it’s our recommendation to put Atrazine in there with it. And that's a lot of herbicide for that corn plant to metabolize and deal with in addition to cool and wet conditions. It seems a lot of times if we put a big slug of herbicide like that out early under these conditions we're talking about, you're going to get some white flashing, especially if that boom ever overlaps. You get some severe stunting where we get our rate up a little too high. But even without doing that, we can still get some yellow flashing and white flashing, from just the inability of that corn plant to metabolize some of that heavy dose of herbicide. And while I'm talking about that, and it's not necessarily specific to Halex GT – but due to the herbicide shortages going on, the difficulty to find different products, a lot of people might try to roll their own Halex or row their own “name your most common, popular herbicide pre-mix.” And what you have to watch out for in some of those situations is Callisto, for example, is an EC. Dual, is an EC. Roundup PowerMax 3 is a heavy loaded, surfactant based, solvent based glyphosate product. So if I roll my own Halex, I've got a lot of solvents and a lot of oils, then I add atrazine to that in the tank. Versus when it's pre-formulated, they're a little different. It's not an additive effect of all those solvents and oils. And so, you will get a lot more burn in general when you start rolling your own or mixing your own individual products together sometimes. So just be careful with that.

Tommy: Along that conversation too. I was just going to chime in. We always say this, and I know no one likes to do it, but check those labels, right? Read those labels. Because when you're rolling your own, a lot of those different individual actives, especially if you start talking generics versus brand name, may have different loads. Just as an example, let's just talk about the glyphosates of the world, right? The Roundups. I mean, we've got I think there's 3-pound materials out there. There's 4, 4.5, 4.8. You know, there's a whole range of different loads of those glyphosates out there. We got to know which one we're using to select the right rate. If we find one of those 3 or 4 pounds, whatever it is, and we're running a normal court rate, well, that's actually low, right? The court rates for the 4.5 or 4.8 pounds. So just be aware of that. And the same goes for a lot of those other ones. Like Tom has mentioned, when you're rolling your own Halex, you've got generic meso or a generic something else, generic atrazine. Those loads might be just a little bit different. Just double check those and make sure you're getting the right amount of active actually in there and you're not either under or over applying them. Tom, did you have anything else on the residuals front or any other weeds of concerns or anything else you wanted to chat about?

Tom: Well, there's a lot of situational things out there. And I think our winter, I don't know how many winters we've had this year [laughter] but our temperatures – we never have a normal spring anymore. I don't know what that means. But, we'll have some winter annuals that are absolutely huge and bigger than I've ever seen. I've seen pictures of Virginia buttonweed and Shepherd's Purse that I don't think I've ever seen them that big this time of year. We just usually, easily kill them with our pre-plant burndown applications. But, there's going to be some specific things that may cause you trouble. And all I'll say is, if you've got a – you know, that's why we're here, that's why we have these roles and do this job. And so, always reach out to us if you've got any specific questions or concerns or if there's any crazy weed out in the field. I mean, don't just assume that we know about it or know what's going on, and we might want to come out and put a little squirt and look test on you. So anyway.

Tommy: Yeah, we'll do our best. We don't guarantee anything ever, but we'll do our best. So we'll try. But just along those lines too, just with some other outreach things. Make sure to always be checking our website for any updated information there. Visit your local extension office, talk to your county agents and hopefully they can help you. And if not, they always have our contact info too, and they can get a hold of us all and grab an MP 44 to make sure you have that guide in your in your truck or on your phone. You can download it from online too and have an online copy. Make sure you got that in your hands. If you haven’t signed up for our text service, just text W-E-E-D-S to (501) 300-8883 and so you’ve got a lot of different outreach methods. You can get a hold of us any of those different ways. And like Tom mentioned, if you ever have any questions, feel free to email us, give us a phone call, send us text message, any of those types of things as well.

Tom: You know, this MP 519 that I've got sitting here in front of me, because I can't ever remember all the plant-back intervals, is pretty handy to have this time of year. If you've got a question about just a quick reference guide on, “can I spray this plant immediately?” I'm not saying we have every herbicide in there. Matter of fact, I make notes every year, the ones that aren't in there. But it's a pretty, handy little quick reference guide to have this time of year.

Tommy: That's right. And with that, we just wanted to say thanks to you to multiple people as well, like normal. First of all, thank you, the listeners, for continuing to tune in and listen to our podcast and get this information from us. You know, if you ever have a comment or something you want to hear, or something that you didn't like that we said, you know, that's pretty common too. [laughter] I mean, feel free to let us know.

Tom: Send all those to Tommy [laughter]. I don't want to hear what you didn't like.

Tommy: I appreciate. I appreciate it, Tom [laughter]. But no, just let us know. We appreciate the feedback and that y’all are listening and finding this information useful. We also just wanted to say thanks to our Arkansas commodity boards and the USDA-NIFA and the USDA-ARS for all the funding that contributes to not only our research that generates these recommendations, but also it just gives us the opportunity to do these Extension things that we want to do. So we appreciate all of that support as well along the way. So with that Tom, do you have anything else final you want to mention in this week's podcast?

Tom: Hopefully, we can get our get some field work done and it's more things planted.

Tommy: That's right. Yeah, I know the weather forecast isn't looking promising in the next couple of days, but hopefully end of the week weekend, it'll start clearing up and dry out, hopefully. Knock on wood here. But well, with that – like I said, thanks again for listening and thanks for joining us for this episode of The Weeds AR Wild Podcast series on Arkansas Row Crops Radio.

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