Weeds AR Wild S3 Ep14. Dr. Tom Barber discusses the current weed control situation and options for mid-season weed control.
Weeds AR Wild S3 Ep14. Dr. Tom Barber discusses the current weed control situation and options for mid-season weed control.
[00:01] Intro/Outro
Arkansas Row Crops Radio, providing up to date information and timely recommendations on road crop production in Arkansas.
[00:12] Tom Barber
Hello and welcome to another episode of The Weeds AR Wild podcast series on Arkansas Row Crops Radio. This is Tom Barber, extension weed scientist with the University of Arkansas System Division of Agriculture. And unfortunately for all of y'all out there in podcast land, I don't have a guest today, so you'll just have to bear with me as I kinda go through what's happened the last week and some of the calls that we're getting now and hopefully before long, we're going to be able to lay most of this crop by and I won't get any calls anymore and I'll just take off the month of July. And so that'll be great, for me anyway. Now seriously, I wish I could do that, but we all know that's probably not going to happen.
[00:53] Tom Barber
So, some of the topics of the day for this podcast, I believe this is episode 14 if we’ve counted right. And this time of year is usually when we just get a lot of random calls. One of the main ones I'm getting lately is, is my pig weed resistant? And, you know, most of this is following applications of dicamba or glufosinate for the most part. And, you know, our weather pattern has been so crazy, it seems to me this year we've had places that have gotten plenty of rain, some maybe too much rain, and others where we've got very little rain at all, like on some of our research plots there at the Mariana Station. So it's all across the board, I think.
[01:40] Tom Barber
Not only pig weed questions, but also barnyard grass. Those are the two top ones still, as far as calls coming in, and the barnyard grass calls, honestly, that I'm getting the most of lately have been in soybeans or cotton or some cotton fields. And so, between Barnyard, excuse me, barnyard grass, goose grass and pig weed, those are the top three weeds I'm probably getting calls on right now. And are they resistant? Well, it depends obviously on what chemical we're talking about but to loop back around the pig weed, do we have widespread resistance to dicamba?
[02:17] Tom Barber
As far as I know, the answer to that question is, is no. Locally, in some fields we are struggling, I will say based on the calls I've been getting. And some of that might just be due to the dry weather and the other environmental conditions that have plagued us this year. But all in all, we have some areas of the state where you see a lot more pig weed escapes than others.
[02:46] Tom Barber
Northeast Arkansas has always had a target as far as being the, I guess, the ideal environment for pig weed growth and development, because it just seems to grow and produce better there in three or four counties in northeast Arkansas than it does the rest of the state for whatever reason. So we are still struggling with pig weed control in northeast Arkansas.
[03:07] Tom Barber
We do have fields where glufosinate resistance is more widespread. We don't, to my knowledge, have many confirmed dicamba resistant populations through that part of the state. But what I do know from talking to growers and consultants that you know, we may have some increased tolerance at minimum in some of those populations. And so, you know, a lot of that, again, can be solved by environmental conditions sometimes or better application practices. There's several different factors that go into whether a herbicide application is effective or not. But we do know that just across the river in Tennessee, the pig weed resistance to dicamba and 2,4-D is becoming more widespread. So, it'd be foolish for us to think that we don't have some of that over here in Arkansas already. So, what about the grass control failures?
[04:08] Tom Barber
And again, barnyard grass is some of the biggest are the biggest culprits. Some of the questions that I'm getting right now, every year at the end of June, 1st of July, when we see these temperatures go up, I get failed barnyard grass calls. So, we sprayed roundup in the mixture we didn't kill the grass, why? Well, and there's again, many factors that go into that. Number one thing, the grass has to be actively growing. And so, when we see hot, dry conditions, that grass is not going to be actively growing. It’ll actually go into reproductive mode a lot of times and we're just not going to kill it with anything. So, do we have some resistance? We might, we might have some built up resistance to Roundup.
[04:56] Tom Barber
Again, it's across the river in Mississippi. It's across the river in Tennessee. Be foolish to think that we don't have some of that over here. I don't believe it's widespread at this point. But when we talk about goose grass, although there have we have confirmed goose grass, resistance to glyphosate in Arkansas. And I get a lot of calls on goose grass.
[05:18] Tom Barber
And goose grass is another one of those hardy grasses that when it gets this time of year, it's just hard to kill. You basically have to drop a brick on it to do any good. And so, you know, it's not that we've had an increase in resistance. I think as much as it is just the advent of the season and the conditions that we're having and, you know, environmental conditions go a long way and how well our herbicides work, especially on, on goose grass, are very hardy, hardy weed. So I think, you know, for those that have asked we're using, making a fallow application with glyphosate where we've had some failure in putting it in an ACCase, whether it's Clethodim or Select or something that’s got quizalofop in it like Assure II, if you can find some Fuslidae out there. something like that.
[06:15] Tom Barber
But mixing something here with glyphosate to give us a little boost maybe on that follow up application where we've had a failure. The other questions I've been getting lately revolve around programs, which programs are working best. And I was fortunate enough last week to attend the Anheuser-Busch field day at Jonesboro, and I quoted a line I got from a farmer earlier that week who basically summed up the season pretty well, and it doesn't really matter if we're talking about rice or any other crop, but, but basically he said where I got my residuals out and caught the rain, I’m clean. And I think that pretty much sums it up across the board for us. We rely so heavily on residuals anymore, regardless of the crop that we're talking about. We rely on timely application of those residuals, meaning we have to get them out. And then before the crop comes up or before the weeds come up and then we need that timely rainfall to activate those. And without the rain, they're not any good.
[07:21] Tom Barber
And so will they sit there? Yeah, we've talked about they can sit there, but then there's that, that window of time where we’ll apply the residual, it won't be activated because we missed a right or whatever, but the weeds have enough moisture to germinate and come up through the non-activated herbicide. So, the rainfall is just as critical as the timeliness of their residual.
[07:48] Tom Barber
And, and, you know, with our weather pattern this year, it's been hard to place residuals everywhere where they caught a timely rain. I'll use Marianna, the Lee County area, the area around Marianna again, as an example, we've got three or four locations where we put out herbicide research plot. Marianna is one of my biggest ones, but I cannot buy a rain and Marianna when I need it this year.
[08:14] Tom Barber
And so we've had very little rainfall there. Our residual programs are looking ratty at best. When we finally do catch the rain, we've had that window of time where the weeds have already germinated, so we don't have enough reach back to control the weeds. And we're in a mess before we know it. And I think those fields, when you drive around and you see weeds, there's going to be a lot of grass, a lot of pig weeds in some of this crop this year.
[08:4-] Tom Barber
But when you see that, a lot of that goes back to just the timing of that rainfall, and when we put our residuals out and whether or not we got activated in time there. So unfortunately, with pig weed and barnyard grass, some of these other grass is we're living in a world where if we can’t keep them from coming up, we struggle with killing them in the crop for whatever reason, especially this time of year.
[09:05] Tom Barber
So success or not success this year is going to be based on how well we timed our residuals in regards to a rainfall. And as we farm a lot of acres and a lot of this crop, all we've talked about this on the podcast, most of this crop was planted within a two week period. And so it all has to be sprayed about the same time. And, and so, you know, it's hard to get across the ground to be as timely as we need to be. But the rains are critical to success as we know with these residual programs. Do I have a favorite herbicide program? You know, just looking back on the year, what's worked in the past is still performing very well this year. If we're talking about cotton, two residuals up front are still the best. The Coteran, Chaparral combination that we've used in the past. The Coteran, Break combination is very good. I can really tell a difference this year at Marianna where we included dicamba in our pre-emerge program, it is night and day different, just due to the lack of rainfall.
[10:19] Tom Barber
And that's what we've been saying all along these last several years is that dicamba can have a good fit of at plating to give us some insurance when we don't catch a rain to activate those residuals. And so we see that affect really well or we see that major effect at Marianna this year because of the lack of rainfall. Now, down in southeast Arkansas where we have plots or in Newport, we've received some more timely rains, and so we don't see that that affect as much there. But for sure where the rain was lacking and we can see that row to row.
[10:59] Tom Barber
Got a lot of calls this week about layby’s in cotton or how late is it can I go puttng Zidua, or impregnating fertilizer and putting the fertilizer out. And if I stick my cotton agronomist hat on for a second and we've talked about this I think on up or other episodes of the podcast but just general Cotton agronomics, I don't like putting a big load of nitrogen out after bloom really. And so most of our fertilizer is somewhat front end loaded on cotton. A lot of people put some out at planting, followed by a second application around the squaring time or whatever. That initial squaring time for me I think is kind of a good time where we can mix some nitrogen and potash together to get the Zidua on the fertilizer and get enough product out to, to get good coverage. And again, we've talked about that being somewhere around that 250 pound of product mark, as far as how much fertilizer we need to get out there. So, obviously we don't want to do all of that with urea. So, most of it is ammonium sulfate or, you know, ammonium sulfate, potash blend, something like that. And so, where we've done this, again, this is our second or third year now looking at Zidua-impregnated fertilizer, it looks really good. This year is no different. Again, at Marianna, we're struggling to get a rainfall. So, I'm curious to how that's going to play out. We are watering and but as we all know, watering down the row is not as good as a rain. When we're talking about incorporating and movement herbicides especially into the bed portion of the of the field.
[12:41] Tom Barber
So, you know the verdict still out right now. I'm fairly pleased with it. I think it's a good way to get a residual out of this very effective on pig weed. And if, if everybody would break the layby rigs out of the out of the bushes, and the hoods out of the bushes or off the turn row, and get them by going, I think we would be a lot better off and a lot cleaner at harvest in cotton and not just with pig weed and grass. The number one call I got about weeds last year at harvest was grass. And it could be barnyard grass, it may be southwestern cupgrass, millets, there's Texas panicum. There's all kinds of grasses, as we’re watering you know, on a pretty strict schedule, that can come up and break through the any of the last residual we put out.
[13:41] Tom Barber
So laying by just for grass has become, in my opinion, an important process. So again, if we can't get it, if we're not willing to try a new method of, you know, encapsulating or impregnating some of this Zidua, not encapsulated, that's a bad word, it'd be more like impregnating or treating some of this fertilizer to, to get the Zidua on there and get it out that way, then we’re really going to have to take a deep dive, look at either drop nozzles or post-direct rigs to get us an extra residual out to get that layby application out again. So critical in wide row crop production. So, if we're wide row beans, wide row cotton, that layby application, even though it seems to be a pain and nobody wants to do it anymore, for those that are doing it we’re clean. At the end of the year, at, at harvest we are definitely cleaner. Got some questions on, you know the Valor, what's the best layby in cotton, if we're going to put one out, Valor or Fierce. Especially Fierce in my mind is one of the better ones. For anything that has Valor in it or flumioxazin it, from a herbicide standpoint, we need at least three inches of bark and we need a good operator that doesn't raise the layby rig or hoods because if we hit that green stem tissue, we can cut some of those cotton plants. They might break over a later once they get heavy. So again, it does take a little slower. It's a, it's a slower process if everybody remembers. But it is critical in maintaining a weed- free field through, through harvest.
[15:32] Tom Barber
Diuron, you know, I don't know how much longer we'll be able to use Diuron after this year, but while we can use it, it’s cheap and it goes a long way as, as an application. I mean, that used to be the standard, MSMA, Diuron, RoundUp, you know pretty good layby program in cotton, and it’s pretty cheap.
[15:55] Tom Barber
So, I guess the point I'm trying to make is we're about to reach a critical time where I think we're going to have to either start applying some of our residuals on our fertilizer or have the mindset that we're just going to have to take the time to break these layby rigs out, especially in our problem fields, and get some more residual herbicide out there before the cotton canopies.
[16:22] Tom Barber
So I think I'm going to close with that. As always, I know that many of you have commented and sent us some, not necessarily hearing a lot of critiques, but just ideas for the podcast. So if y'all, if you all want to continue to do that, we welcome that. If you have any critiques about the podcast, I think you should contact Tommy Butts as we move all complaints, he's in charge of the complaint department, so send all those complaints to him. I'd appreciate that. But as always, we want to thank you for tuning in, especially today, to hear me ramble on about weed control by myself. And again, if you need to shoot us an email, you can shoot me an email at tbarber@uada.edu. Thanks for joining us on this episode of the Weeds AR Wild podcast series on Arkansas Row Crops Radio.
[17:18] Intro/Outro
Arkansas Row Crops Radio is a production of the University of Arkansas System Division of Agriculture. For more information, please contact your local county extension agent or visit uaex.uada.edu.