Weeds AR Wild Series, Season 2 Episode 3. Title: Check Soybean Tolerance to Metribuzin Date: March 4, 2022 [Music]: Arkansas Row Crops Radio providing up to date information and timely recommendations on road crop production in Arkansas. Dr. Jason Norsworthy: Welcome to the Weeds or Wild podcast series as a part of the Arkansas Row Crops Radio. My name is Jason Norsworthy, and I hold the rank of Distinguished Professor of Weed Science with the University of Arkansas System Division of Agriculture. And I'm excited today to be joined by Dr. Jeremy Ross, our Soybean Specialist. Jeremy, hey, thanks for being with us today. Dr. Jeremy Ross: Hey, Jason. Appreciate the opportunity to get onto the podcast and talk a little bit about soybeans. Jason: Yeah, Jeremy. So today we want to talk about soybeans, and we're going to talk some also about metribuzin, that's going to kind of be the focus. But before we get started today, yeah, we’re – I’m going to say – we’re four or five weeks before we probably get serious, at least in the southern portion of the state, to start planting some soybeans. What are you hearing about soybean acreage this year? Jeremy: Well, so yeah, you're right. I mean, we're a little, few weeks off, to really getting and started and just do one to make a note, I got a call a couple of weeks ago and I know there was 50 acres of beans planted on February the 18th. So we've actually got some beans planted in the state. But you know, that was down in the southeast Arkansas and haven't heard yet, you know, if they've got a decent stand. But we've had some pretty cold conditions, you know, since February the 18th. But you know, today, yesterday it was almost 80. I think the rest of the week is supposed to be pretty warm but I think another cool snaps coming, you know in another seven days. But now's the time to be thinking about getting ready to start planting, you know all of our data shows that, you know, especially in southeast Arkansas if we can shoot for around April 1st on getting planted, it's where we can maximize yield. And then as you go further north in the state, you know, that gets pushed back to, you know, the middle April to first of May. So really been pushing, planting dates and trying to get that information out. Acreage-wise from the meeting circuit, for the last two months, I've talked to a number of growers. You know, I think there's still some decisions to be made. I think we'll have a little bit more acreage of soybeans this year compared to the last couple of years. We were down below 3 million acres in 19 and 20 and it finally broke over that 3 million mark again in 2021. So we're going to be over that 3 million mark again for 2022. But you know how far over, I don't know. We probably gain at least, you know, I'd say another 200,000 acres from some of the other commodities just because of, you know, prices of soybeans right now. And then some of the input cost. And you know, we all know that, you know that fertility is up. Pesticide costs are up, and then availability is going to be a big thing. So I think there's going to be a few more acres of soybeans this year. But really, it’s all going to be dependent upon what the next few weeks does on the markets. And then, you know, kind of what our weather is for the next two or three months. Jason: Jeremy, when we think about soybean and we think about weed control, in soybean, palmer amaranth by far is our number one weed that we deal with here in Arkansas, and I'd just say the Mid-South as a whole. And one thing that we've got to do if we're going to be effective in terms of managing palmer amaranth is start with a good clean seedbed and lay down a very strong residual herbicide. And one thing that we have seen in our research for the last I'm going to say probably the last five or six years, where we have these bio-types or populations of Palmer Amaranth that’s resistant to multiple herbicides, is that we really need metribuzin as part of our pre-emergence program. And what we have found is metribuzin alone is not necessarily the answer but metribuzin in mixture with some other pre-emergence herbicides has been quite effective. And when I look at the options that we have in soybean today, there's a wide assortment of mixtures, commercial mixtures, that are out there, that can be bought. I just jotted down here a list yesterday and some that come to mind are things like Canopy, which is a mixture of classic and metribuzin. And you've got products like Boundary, Trivence, you have Moccasin MTZ, Tripsyn, Authority MTZ, Kyber, which is a mixture of Valor, Zidua and metribuzin. And you've got Intimidator. There's a wide assortment of products, again, that we can put out there. And what we have found is when we have two herbicides, metribuzin, plus another herbicide - on that ground, generally we're able to get 90% or better pigweed control for four or five weeks into the growing season. But when we think about metribuzin and it's a herbicide that's been around for some time, there also can be some problems with metribuzin, in the sense that we know that we also have varieties out there that are very sensitive to metribuzin. And you've got to choose a tolerant variety. And, you know, we take part in this, this screening where every fall we screen for metribuzin tolerance in terms of the cultivars that we're entered into the Arkansas OVT program. And last year we evaluated a 152 cultivars, and that information is now available online to the growers so that you can make a very informed decision as what's going to be tolerant to metribuzin, when you choose one of these products. Jeremy, I know you spent some time over the last few months taking a look at the, the results from that document that is out there on the web now, looking at metribuzin tolerance and what are your thoughts? What are some of the conclusions that you've actually reached based on reviewing that document? Jeremy: Yeah. So you know, as Jason mentioned, that that data is available on our website, and you can find in a couple of different forms. We've got actually a standalone metribuzin document. And then that metribuzin data is also available in the soybean update along with other agronomic characteristics. So just wanted to kind of make that known that we've got a couple of different avenues for, you know, finding out this information and making sure that producers are educated on these varieties. But I've spent quite a bit of time looking at, you know, the OVT data from last year, as Jason mentioned, and we evaluated about 152 individual varieties. And so after kind of looking at the ratings for this year, really we're kind of surprised at, you know, the number of varieties that we, that we consider severe injury and so in that situation, you know, we wouldn't recommend any form of metribuzin to be applied on those varieties because they, you know, you'd see pretty much, you know, kill your stand. Jason: Especially under cold, wet conditions. Jeremy: Right. And so, you know, when I presented the data at the variety or during the production meeting season, I kind of group, you know, varieties that’s kind of the top ten varieties across multiple locations. And so, you know, it really surprises, especially once we got into our group five ExtendFlex varieties, the percentage of the top yield and varieties that that we consider severe injury to metribuzin. And and so you know, if you look at the data, the majority of the varieties are going to be, you know, considered either slight or moderate. Um, tolerance to metribuzin, or injury. But we did have 25 varieties, out of the 152 that we pretty much deemed severe injury. And so if you kind of look at the breakdown of those, you know, especially if you look at the Enlist, the Roundup Ready Extend varieties and then now the ExtendFlex varieties. Of the 25 varieties, about 20% or five varieties is in the Enlist technology is what we consider severe. Seven Extend varieties or about 28% of those severe varieties. And then the largest group, we had nine varieties out of the ExtendFlex technology that we considered severe. And if you actually go and look at the data and kind of sought the data by the highest yielding varieties, especially in our group fives, five out of the top ten varieties, you know in the group five ExtendFlex test, is what we consider severe. And so that kind of, you know, kind of threw up some red flags to me because, you know, a lot of producers will just kind of look at yields and, you know, and see how these varieties perform. Sometimes they may not look at the metribuzin score. Hopefully they will, to make sure that, you know, metribuzin can be used in their herbicide program. But I just wanted to kind of reiterate that this year it seems like we saw you know, a higher percentage of the higher yielding varieties showing sensitivity to metribuzin in 2021, and just wanted to kind of make sure producers were aware of that. I'd hate for a producer to pick a high yielding variety and not look at the metribuzin ratings. And then you know apply metribuzin, and then has some cool conditions, or you know, or soil texture or ph - that just causes a little bit more injury in metribuzin and loses stand. Because you know the way this year is, you know, we're going to have to do everything we can to make sure we get a good stand and try not to use any extra inputs during 2022 just because of the, you know, the herbicide issues and, you know, fertility issues and some of these other issues. So just kind of wanting to kind of make everybody aware that. But I've been, you know, every production meeting. I’ve pointed that out and hopefully we can, we've got the word out and everybody be aware of that. Jason: In addition to us having this information on the website. You know, if you go to your local seed supplier, hopefully they will also have some testing. I know that Pioneer, I believe, does a good job of testing and putting metribuzin sensitivity on some of their seed. And so there should be, when you purchase seed, you should be able to ask your seed supplier as to whether or not that soybean variety is actually tolerant to metribuzin. Something else that Jeremy touched on here just a second ago, he said ph and he also mentioned soil texture. Soil texture is really going to dictate the rate of metribuzin that we use. And if we're going to use metribuzin in combination with another herbicide, it's all about getting the correct rate out there. Some of these pre-mixes are extremely low rates of metribuzin and we don't see the benefit of metribuzin there that we would get a versus a full rate of the herbicide. And when I say full rate of the herbicide, I'm talking a half a pound of active ingredient on a silt loam soil which would be equivalent to 10.67 ounces of a dry material that being like something like TriCore 75DF, if you're actually working with a liquid TriCore 4F - that would be equivalent to a pint per acre. On a clay soil, you're basically going to be able to double those rates. The other thing that we need to think about is the ph. Again, on those soils that have a tendency to have a high ph, and when I say a ph, when we start getting over seven, the risk for metribuzin injury is going to increase substantially. And if you start looking at the labels, the labels are actually going to tell you if you have a seven and a half or higher ph, don't apply metribuzin. Organic matter also is going to have an impact if we're less than far less than half a percent organic matter, the risk of seeing damage associated with metribuzin is likewise going to increase. But you know, we've talked a little bit about some of the risks we've talked about. Again, the concerns Jeremy has maybe as it relates to some of these higher yielding varieties. But I don't want to leave the audience here today thinking that, again, metribuzin is not a herbicide that we need to be using. Because, all of the work that we've done myself, Dr. Tom Barber, we've been on a lot of PPO resistant, ALS, glyphosate resistant, you name it, a wide assortment of resistances within Palmer Amaranth. And what we see year after year is, we've got to have that full rate of metribuzin and in combination with another herbicide and nothing else that we've looked at in our program has stacked up and provided comparable levels of control. If you have a PPO resistant pigweed, these other products just really are not going to provide you a level of control that you're going to expect on these resistant populations. So again, I'm a big fan of metribuzin, and it's got to fit in Arkansas. Actually, we widely use it across the state as well as the Mid-South. And hopefully our growers can find a variety that works with them in conjunction with metribuzin. And so, with that, Jeremy, is there anything else you'd like to add as it relates to metal abuse and or soybean? Jeremy: No, I mean, I've pretty much followed either Tom or Tommy on the meeting circuit this year. And, you know, herbicides are going to be an issue this year. Again, because of supply and demand. And, you know, listening to Tommy talk and to Tom, you know, we're going to need to rely on these pre-emerge herbicides and start clean, stay clean early in the season because, you know, some of the post applications are going to be kind of hard to get. And so you know, definitely we need to be using multiple modes of action and metribuzin needs to be one of those products that we need to be doing. But again, just you know, look at the list and make sure that the varieties you are planting or tolerate to metribuzin. And because I'd hate for anything bad to happen and you lose a stand, just because, you know, a farmer’s not educated enough, so well. Jason: Well, Jeremy, hey, I appreciate you being with us today. Next week, I think Dr. Barber will be the one that will be delivering the podcast. And I want to say thanks to you, for joining us - the audience - for this episode of the Weeds or Wild podcast series on the Arkansas Rock Crops Radio. [Music]: 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.