Drs. Tom Barber, Bob Scott and Jason Norsworthy discuss Italian ryegrass burndown mixtures prior to planting, glyphosate-resistant annual bluegrass (Poa), BMP’s for glufosinate applications and necessary residuals for a successful start to rice weed control.
Drs. Tom Barber, Bob Scott and Jason Norsworthy discuss Italian ryegrass burndown mixtures prior to planting, glyphosate-resistant annual bluegrass (Poa), BMP’s for glufosinate applications and necessary residuals for a successful start to rice weed control.
[00:03] Tom Barber
Hello and welcome to the Weeds AR Wild podcast series as a part of Arkansas Row Crops Radio. This is Tom Barber, extension weed scientist with the University of Arkansas System Division of Agriculture. This is gonna be the first episode and Season 4 of the Weeds Are Wild podcast. And, the previous three seasons, I think we've had some great success.
I've had some good feedback from agents and consultants and farmers out in the state. And so we're looking for hot topics for this season to discuss as we move forward. But, for the first episode, I've got my fellow wheat scientists, Dr. Bob Scott and Dr. Jason Norsworthy joining me today, and we're going to discuss a whole range of issues.
So, fellas, welcome to the program. And how's everybody doing on this April Fool’s Day?
[00:51] Bob Scott
Doing all right Tom, and I want to start out by saying it's good to be back in the weed science fold.
[00:57] Tom Barber
Yeah. That's right. We can talk openly now, since you're not our boss anymore.
[01:01] Bob Scott
Yeah, but you're my boss at the moment, so that's, that's true.
[01:05] Jason Norsworthy
Yeah. It's good to get the year started, Tom. And I'm looking forward to talking about some of the topics. You know, as you mentioned, the phone has started to ring and I'm looking forward to hopefully this, in this episode, starting to address some of the questions that we've been getting.
[01:20] Tom Barber
Well, all right. So on that, let's kick it off. I know a lot of us have been fielding some calls on burn down. Obviously, you know, we're just now the 1st of April and as normal everybody feels like they're a couple weeks behind already, I think, from a from a farmer’s standpoint. So I know the planters started rolling, this past Friday, for the most part, but we're still getting a lot of questions on burn down right before planting.
And probably the number one issue with that is rye grass, and so when we talk about glyphosate resistant rye grass, there's a lot of questions that come to mind. You know, programs, what rates, formulations, take mixtures and, important key plant back interval. So I think we'll just start with, talking about general recommendations and what we've been talking about through the winter has been, you know, if the rye grass is overwintered and it's getting to a point where we've got a lot of tillers all in and it's a big clump of rye grass, generally, I tend to move away from a clefidem or select based herbicide program,
just because number one, it seems to take a lot of select rate when the plant gets that big to, to kill it. And then two paraquat plus a PS2 inhibitor is much quicker and seems to be more effective on those larger ryegrass plants. But when we go back to select rates and, and tank mixtures,
oh, what kind of calls have y'all been getting I guess. And what kind of rates are we recommending if we're going to go the Select or Clefidem route?
[03:04] Jason Norsworthy
You know, I think what you just touched on there, I think rate is one of the questions, how much does it take to kill it? And, you know, if you are going to go with select today based on the size of the, on the size of that ryegrass, I'm going to tell you, you can't cut back on rate.
You're going to have to use the full rate select max. That's going to be 16oz of, of that, of that product. I think you can go a little bit higher on some of the generic but select max, that's where you're going to be. And you know, with that it's going to take every bit of two weeks, if not three weeks to actually kill that the ryegrass.
And so with that, I just I think there's probably better options. There's like you said, the Paraquat’s a better option at this time. The other problem I run into, or, you know, folks are not going to want to put out select at this point and see it for, essentially a month waiting on planting corn, waiting on planting rice.
And so along those same lines, the next question when we start talking about select layer is ask questions about select rate is how soon can I go behind that and plant rice or can I plant corn. And the answer to that is if there's a month plant back at that full rate. And I just want to caution everyone and let them understand that that plant back is real.
We've done a lot of work where we've gone in and tried to plant 14 days behind that, and more often than not, you're going to fail to get a stand. So if plant back is a concern for you, that's another reason to push you back over to the paraquat, paraquat atrazine, paraquat metribuzin and paraquat directs depending on what you're looking at putting in the field behind it.
[04:54] Bob Scott
Yeah. And, going back to what you said before, Tom, about the size and kind of switching over to that paraquat PS2, I've only been back in the office for a couple weeks, but I've already been to a couple of fields and actually sampled one of the fields where we weren't able to get it with select, and I feel like it was probably just too big.
And so a couple things, you know, that puts you a little bit behind on your burndown, trying to get in there and plant, but it also means a later application now trying to come and clean that up with paraquat. And whichever PS2 I don't know which one they're using because I'm not sure what they were planting back in the field, but say it was metribuzin for beans, so that just doubled the cost, you know, of that, that burndown going back in, we probably should have been at paraquat first in that particular field.
So just one of those things to watch out for.
[05:47] Tom Barber
Well, and I know, I've got a lot of questions on the rate of select and the MP 44. And of course we can't put every generic version of select in the MP 44. But you know, select max, we do have it in there. I did you increase the rate. It does go up to 32oz in the MP 44.
That's really a perennial grass rate. But the whole idea there is to show the range, I guess, of what we do have to work with on some fallow ground. And then also when we get to some of these generics, like section three, for example, it doesn't distinguish as much on the rate of Clefidem for perennial and non-perennial grasses. And so it just goes up to that equivalent 32oz. So if you are still using select, number one or a clefidem, know what formulation it is, know how it is formulated. Whether it's a 1 pound like select max or a 2 pound, or a 3 pound like this section three, to get your rate correct on that application.
And then the other thing I get a lot of questions on is I guess it's in the corn, taking out a failed stand a corn section, in the MP 44, and where we have a reduced rate of select, where we can plant back in seven days. That is not a rate that we recommend for ryegrass control. That is just a rate to take out a corn stand.
So, and that's the only time we can replant within that 30-day window. And every year I walk fields, especially on our sandy or soils where we have an issue with planting too quickly behind that select application, like Jason was saying to where, you know, say in two weeks or, or whatever. I see it every year. So it's real, just be mindful of that.
And then the other thing, if we definitely set on select or clefidem, I'd say just watch the antagonism when we move into oxin tank mixtures, whether that's dicamba or 24D, especially those two I think, especially as that ryegrass plant grows and is larger, we're going to see some reduced efficacy in those situations.
So main story on ryegrass now, for most of our fields we’re probably in that paraquat recommendation. As far as what we would recommend, if you all agree with that and then putting a PS2 inhibitor with it, if it's beans that can be metribuzin, technically, yes, we can do that in front of corn as well.
If it's cotton it could be diuron or cotteran, something like that for rye. So unfortunately we really don't have one.
[08:26] Bob Scott
And we're not really talking about a full rate there, right?
[08:29] Tom Barber
Right. Yeah. So we're to say like three ounces of metribuzin, right, is equivalent. We could do it with a pint of atrazine in front of corn, on a diuron or less even, ten ounces or so. And so yes. Doesn't have to be a full rate. But, anything else on ryegrass before we . . .
[08:49] Jason Norsworthy
The one thing I’d just like to say about ryegrass, this is kind of even going back to where we started here is, you know, I think most of our growers south of I-40, they've had ryegrass now for many years. Our growers that are north of I-40, this is tending to be a new weed for them in terms of burn down.
And I just want to caution everyone, if you have ryegrass in your field, you better make the assumption that it's glyphosate resistant. We have a little bit less susceptible out there that most of it is going to be resistant to glyphosate, and I think that you just get behind the eight ball when you go out there and you start spraying this stuff with glyphosate. It's going to get big on you because glyphosate generally is not, is not effective. And then the last thing that I want to say on ryegrass, we've got to do a better job of keeping this stuff from going to seed and not only seed in the field, but I think seed on the edge of the fields. I've seen that where it’s creeping into our fields from these spill margins, just like any other weed.
It's going to become problematic if we if we let it go seed.
[10:00] Bob Scott
Well, one other quick thing I guess I would mention is, there was some fall residuals that went out, this year. Jason, for ryegrass, duo being one of those and, I think in Jared Hardkes’ last newsletter, he pointed out that it is not safe to plant rice, you know, back into those fields.
And that applies to several of the, coracedimite type products or, group, remind me, Group 15.
[10:31] Jason Norsworthy
Group 15 herbicides. I would agree with that, Bob. And I will tell you, we, we've done a lot of work with fall applications. If you put out residual in the fall, if you put out duel in the fall, there's, I would not want to plant rice behind that. More often than not, you're going to fail to get a stand if you put those out in the fall.
[10:55] Bob Scott
And, I guess finally, on this subject of ryegrass and, and breaking through these burndown programs you're interested in or have the ability to test these, right? Correct? But not only ryegrass, but maybe annual bluegrass. We haven't talked about that one yet, but.
[11:15] Jason Norsworthy
Ryegrass, annual bluegrass, any of these grasses I don't want to go and test for glyphosate resistance, folks. We have glyphosate resistance everywhere. You better make the assumption. It's kind of like the pigweed. All pigweed resistant to glyfosate today, make the assumption all ryegrass is resistant to glyphosate. But if for some reason an individual had failure of, clefidem, Select, I'd be more than happy to test that.
All you need to do is, you need to get, I would, I want to see 10 to 15 clumps that you collect seed from. You get those, you're going to make sure that they're mature seed from those, get as many panicles from those clumps as you as you can, put those in paper sacks. Once they have dried down, take them to your county agent.
Your county agent has a herbicide resistance form. We need to know where they were collected from, preferably GPS coordinates. Also want to know what was sprayed on that population? Send it in to me and then I'd be more than happy to test for clefidem. And I'm going to kind of jump ahead here. We'll talk some about annual bluegrass, but we're starting to see some failure of glyphosate on annual bluegrass.
I'd be more than happy to test that. Now, when folks call me and I've had several consultants call over issues like this this spring, I want to remind everyone I'm not asking. Do not allow this stuff to go to seed in the field so that you can get a sample. The last thing you want to do is be spreading clefidem resistant ryegrass, glyphosate resistant bluegrass. Do everything you can to kill it.
But before you make that final application, if you want to dig up some clumps and put them in a five-gallon bucket, bring them to your house, grow them out so you can get a seed sample. Again, I'd be more than happy to test, but I would not set aside a small area in the field and let it grow out because again, if it is resistant, you're going to have a significant, significant problem, the coming year if this stuff goes to seed.
[13:20] Tom Barber
Absolutely. yes. That's great advice. And I think that, you know, if we have a miss on bluegrass from glyphosate, really the next best thing is probably paraquat is what I've been telling most folks. Do y'all have a better.
[13:36] Jason Norsworthy
That's what I've been telling. I've had some folks ask me about using some ALS herbicides. We have not had a chance to, to test these. I think paraquat is the, the sure one. You know, the glyphosate resistant powen that we have up in in Poinsett County. I haven't sprayed it yet with, with paraquat, but going out today, that's what I would do.
I'd go paraquat and again, I'd put a PS2 herbicide in it. It's just going to make paraquat a better product.
[14:06] Bob Scott
I'm going to tell you it's a little bit firm and ugly too. But you know, there's been some work done in rice and beans both, I believe a little bit of fertilizer, mainly in rice, with the nitrogen, can overcome any competition from what's left of that annual bluegrass. But it is kind of an eyesore out there.
And it will, hurt yields if it's thick as hair on a dog's back.
[14:28] Tom Barber
It's hard sometimes. If we're in a system where we're rehipping or condition in our beds that they're huge clumps, you know it, you know, it can kind of clog the system or make our beds uneven. And so I think, you know, if it is really big, that can cause some of those issues. So, best to get out there and probably make another application to kill it if we can, because we don't ever know when we're going to get back in the field.
But, the.
[14:58] Jason Norsworthy
One thing though, again, just about bluegrass as well as ryegrass, just, Tom you've already, you touched on it, but I want to reiterate is, when you start placing other herbicides in the tank, if you've got clefidem that you're going after this and even some of the ls herbicides, you start mixing things together. We have a tendency to start missing grasses, enhance again the value, I think of going out with paraquat.
It's going to be a lot more forgiving. You don't have paint. You don't have antagonism with paraquat like you do with other herbicides. But I'll get calls. Folks wanting to tank mixed glyphosate and tank mixed paraquat. Want to tank mix dicamba and tank mix paraquat. And maybe there are some scenarios where we need to tank mix those. But in general, if you take a systemic herbicide and you mix it with a contact herbicide, you're going to reduce the activity of that systemic herbicide.
[15:59] Tom Barber
Great points, great points. All right. That's my, my notes for wrapping up burndown. Anything else that we left off? Can’t think of anything. All right. So another hot topic of late, and this has been a conversation over the last at least week to ten days, is, you know, whether it's the lack of availability of approved dicamba formulations or in certain areas of the state.
We're hearing a lot of reports from last year of reduced activity, or you know, lack of results when using dicamba on pigweed. But, I've had a lot of discussions over, like I said, the last ten days with growers and consultants and, and everyone about shifting back to more of a glufosonate based program or Liberty based program.
And so a lot of questions have been coming up. And, you know, it doesn't seem that long to me, guys, but, you know, I know, if we're not using things, we forget about the setups we need and we forget about the best management practices. But one thing we know for sure, and we're probably going to repeat every time we do one of these programs, is we need to change our nozzle setup.
if we're going back to a glufosonate based system. So the tti’s are out. In my mind, if we're talking about Liberty or glufosonate. Comments?
[17:26] Jason Norsworthy
I would agree with you totally on that, Dr. Barber. It's, I mean, you're going to give up, you're going to give up 20, 30 percentage points of weed control if you go to, if you keep that TTI on there. And I know it's, it's a challenge to go in there and start changing those nozzles rotating from one to another.
But I don't see where you have an option of doing anything other than moving to it. You basically have to have a medium to coarse droplet size. You know, aixr’s, I don't want to have any, that's going to in the most, in most instances that's going to produce a coarse droplet. I don't want to be any larger than that.
The other thing you've got to remember about glufosonate is that, that herbicide, I don't think, with it being a contact herbicide, it's not as forgiving. And what I mean by that is once you start getting weeds out there five, six inches in size, pig weed and, you know, grasses are probably kind of the Achilles heel at times of glufosonate.
And when you start stretching that from a weed size, standpoint, you're going to see a lot more failures if you don't have that droplet spectrum optimized. And you need to make sure you're running a running a full right, you're running those on, on small weeds. I think if we take a look at glufosonate today, it's safe to say, you mentioned dicamba.
But I will tell you all the oxygen herbicides as well as glufosonate, you know we're seeing some slippage in in all of these herbicides. It's just the nature of when you use them year after year after year, the performance of those herbicides begin to diminish over time. And we need to be mindful of that. And for that reason, we need to make sure we're doing everything possible to ensure that we optimize the level of weed control that we're going to get. From a timing standpoint, need to make sure we have residuals in the tank.
When we come over the top, we have to glufosonate. We're spraying small weeds.
[19:32] Bob Scott
I agree 100%. I think that was a mistake. You know, if you look back several years back when we introduced or when we reintroduced Liberty Link or Glufosonate and tolerant soybeans, everybody was used to farming with roundup. And, I think the first kind of inclination was to try to use it in that same way. And so we saw a lot of failures, right out the gate that I think can be attributed to weed size and, you know, things like nozzle selection and GPA and stuff like that.
So we don't want to make those same mistakes again. If you've been in a dicamba based program, dicamba roundup type program for the last couple years, and you're switching to Liberty, it's a different herbicide. It has different requirements in order to be successful.
[20:20] Jason Norsworthy
The other thing that I would you state about glufosonate, you know, the that's a generic herbicide today. There's a lot of formulations out there. I don't claim to have sprayed all of them. The ones that I have sprayed, I will tell you at times they can differ in terms of activity. Some are better than others, some are more injurious to crops than others.
You know, Dr. Barber, when you talking extend flex cotton and you got one, two leaf cotton out there and you start coming over the top with glufosonate, it's tolerance at times is somewhat questionable to glufosonate early. And, you know, we like to overlay these residual herbicides and you start putting some things like metolochlor in there or worn in there.
I mean, your product of choice to tank mix, to try to lay that residual down. You can have some issues. And so I just, I want to remind everyone that you probably need to make sure that you've got a good glufosonate formulation that you feel comfortable with, that you've worked with in the past. All these formulations are beginning also to differ.
We're going to start seeing these elastomer forms that are starting, that are going to come to the market. If they're not here, I don't know whether some is going to be available this year, but if they're not this year, you're going to see them here in the next year or two. I know we got surmised five out there today, which is completely different than the old surmise formulation.
If you're not careful and you go out and spray surmise five at a quart per acre over the top of inflate, extend flex cotton, you may be replanting extend flex cotton if that cotton was, was small.
[22:07] Tom Barber
Yeah. And I've already had that question this year already about surmise five. And so, for those that you that don't know, it is a heavy formulation of glufosonate by double, I guess. And so a normal standard, what we'd call standard liberty generic glufosonate was 2.34.
[22:30] Jason Norsworthy
2.34, that’s right.
[22:31] Tom Barber
And so the surmise five is double that. It's 4.68, I guess. And so, a quart of Liberty is a standard rate. But a quart of surmise five is a 2X, rate. And if you put that with metolochlor or outlook and put it over the top of cotton, it's 2 or 3 leaf, you might not be able to roll that cotton out the next day or two.
So, it's we laugh about it, but don't get caught, you know, without knowing what you're putting out. And so, it's not going to be funny if you call me and you've done that. So, it's going to be serious and, just know what you're spraying. And, you know, one of those different isomers like you were talking about Jason, you know, Liberty Ultra, I haven't heard, you know, where there's going to be a lot of that available or not. I know there's going to be several of those coming down the pipe in the future by 2025 anyway. So, you know, when in all our program, when we look at cotton and we talk about, extend flex cotton, and if dicamba is in that first application, a lot of our best programs, include a dicamba early, followed by glufosonate.
And in the, in that second, you know, over the top application. And so I think, you know, with the lack of available formulations for dicamba and for those that don't know what we're talking about there, of course, there was a court that vacated the labels back in February, but we're able to use the existing product that was in the, the chain of supply chain of extendamax and, and Genia and Tavian.
And so when those are out we're done. And so, you know, if we're got an extend soybean out there, we might be in trouble at that point if we don't have an option to spray over the top of straight extends, so that's another thing to keep in mind. That's probably a little late in the game to change the seed that you've got now, but the extend flex would be much better than extend.
And so, gives you more options over the top. Anything else but glufosonate. You know, I have my points here, changing from tti’s, to coarse nozzles, at least coarse, cause like you mentioned, the aixr’s, if we increase pressure a little bit, we can bust up those droplets a little bit more to spray glufosonate. GPA is your friend and 15 to 20 GPA, spraying during banking hours. We know what that is right, 9 to 5 or so. including ams. Like you said. Make sure you know which glufosonate you’re spraying. And, most importantly, with any of these systems, start with a robust, effective residual program. And so we can't leave it without saying that. Anything I left out on that Bob?
Any comments?
[25:29] Bob Scott
No, I think you got it.
[25:31] Tom Barber
All right.
[25:31] Jason Norsworthy
I think you're spot on.
[25:34] Tom Barber
All right, let's talk a little bit about rice. I bet there's rice going in the ground. Matter of fact, I know there he is right now, today as we speak. So anything y'all are hearing on the rice side of things.
[25:45] Bob Scott
There is.
[25:46] Jason Norsworthy
Folks are planning. You're right about that. I've had some phone calls from folks planting, and, everyone knows where I am on rice. Let's start every acre with a residual down at planting. I like to put Facet or Quinstar with clomazone.
Just as a reminder, we touched on it here last week with glufosinate. If you go with Quinstar, that's a completely different formulation than Facet. You got a 4-pound material with Quinstar. It's a 1.5-pound material with Facet. And so just make sure that you're matching your use rate with that actual product for the soil texture.
The reason I like quinclorac at planting is we've got a tremendous amount of quinchlorac-resistant barnyardgrass out there today. We have no activity on it postemergence with quinclorac. We still get activity on it preemergence. I like to wait when I put my preemergence out. I tell folks let's wait until it rains.
As soon as it rains, let's think about getting another residual out. You know that might be seven days. That might be ten days before you get your rainfall. But as soon as you get a rainfall, let's get a plane back in the field if you can. Let's get one of those delayed pre’s out, a Prowl or Bolero, something where we're overlaying those residual herbicides trying to get into that early postemergence application.
I don't want to sit there and wait, especially if I have dry conditions and I have a flush before I get that clomazone and Facet activated. I'm going to have to come in sooner rather than later with that post-emergence herbicide and try to clean up those barnyard grass plants.
Another reason that I like to put some Bolero in there is a lot of fields out there today. We've got annual surge in, better than 50% of that annual surge is resistant to the ALS chemistry. I like to get in front of it with Bolero. Folks complain about me making that recommendation. They say that's expensive. My response is, you go to flood with, rice flat sage, barnyard grass in the field, you talk about expensive, you're going to start running through $100 bills like there was no tomorrow. If you've got grass in your field or sedge in your field when you go to floods. So that's just kind of where I am in terms of getting the season started off right.
[28:18] Bob Scott
I've been really pleased, Jason, with the calls I've gotten. I've had at least 3 or 4 rice consultants call that that I know cover quite a few acres. If you add up the acres that they're involved on. And I like this change in philosophy that there's been over, using a lot of residuals on the front end and overlap in your pre-emergent, products.
I feel like, you know, I kind of came up in an area where it was, Let's see how cheap we can get by with. Let's use the lowest rated command and see what's left. And, you know, whoever spends the least amount of money wins. But with the resistance problems that we have now, and that's probably part of the reason why we have the resistance problems we have is some of those decisions like that that were made, a lot of guys are going out with just what you said.
I talked to one guy the other day. He had his command and his facet rates down to the ounce, that he felt comfortable with on a little bit lighter soil, he knew exactly what rates he was going to go out with Pre, he was planning on coming back, at the first sign of grass, or the first time that he felt like he could get back in there with a rice bowl followed by prowl. So he was definitely overlapping. That's five modes of action. before that rice, you know, really starts to tiller. And so that's a very good resistance management program. That's, that should be clean. That's a similar program. I don't know about you guys, but if I have a weed free trial that I want to keep weed free and just look at herbicide tolerance or something in rice, that's pretty close to what we do, out in our plots.
So, it's good. It's refreshing to get calls from this many consultants that are thinking along these lines and, you’ll obviously done some education or, or maybe the weeds of educated us over the last few years since I've been, away in administration. But, it's good when the first few calls back are positive like that.
I don't mind taking those.
[30:26] Tom Barber
All right, well, what else we need to talk about on this episode? I know we've got several planned. And just for those that are listening, if you have any ideas of future podcasts, any topics that we need to cover, always email us or text us. Let us know what you want to hear. But, I know, like I said, we've got a lot of planters rolling, planting corn, beans, and rice all at once.
Always amazes me how we can plant the state of Arkansas in like ten days. We need ten days and we can get the bulk of our crop planted. So, it's always amazing to me.
[31:03] Jason Norsworthy
And as a result of that, Dr. Barber, we’ll be back here a month, month and a half, now talking about off target moving to herbicides from another early post.
[31:11] Tom Barber
Yeah. Everybody pay attention to the prevailing winds, especially when they blow out of the North, because that seems to catch us all by surprise. Okay, so anyway, we're not going to have any of that this year, Dr. Norsworthy, we're going to do a good job all around, make an application. So we're going to, we're going to go with that.
Well, guys, thanks for joining me today. Like I said, we've got a full schedule planned. And I know, we'll be hearing more about rice and corn to come in the very near future. Wishing everyone out there safe planting season and want to thank all our listeners for tuning in to this first episode of season four of The Weeds AR Wild podcast series on Arkansas Row Crops Radio.