Title: Weeds AR Wild, Ep. 21: Arkansas and Wisconsin: What's Weed Control Look Like? - Part 1 (8/4/21)

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

Tommy Butts: Welcome to the Weeds AR Wild podcast series as a part of Arkansas Row Crops Radio. My name is Tommy Butts, extension weed scientist for the University of Arkansas System Division of Agriculture. Joining me today is Dr. Rodrigo Werle, from the University of Wisconsin-Madison. We were actually in graduate school together at the University of Nebraska, so Rodrigo and I have known each other for quite a while. We probably have some war stories on each other and all that kind of fun stuff, but with the podcast episode today, what we kind of wanted to hit on was to just get a little bit of background on each of us and then talk about some different weed control strategies across our states. And what might be different but also what might be similar and how we can battle weeds across different geographies kind of thing. So with that I wanted to introduce Rodrigo. Rodrigo, do you want to say hi and give us a little bit of background on your history as well. 

Dr. Rodrigo Werle: Dr. Butts, thank you for the opportunity to be here today. It's an honor to be in your podcast exchanging some information. Hopefully we'll have some good discussions here that might help our listeners out there. As Tommy indicated, him and I graduated in graduate school at University of Nebraska-Lincoln, but an even more interesting fact is that Dr. Butts is from Wisconsin, where I get to work today, so Tommy is also familiar with Wisconsin agriculture and it's going to be helping us a lot with the discussion here, so glad to be here today Tommy. Thanks again for the opportunity. 

Tommy: So along those lines Rodrigo, one of the questions I often get coming from Wisconsin, how much rice do we deal with up there in the state of Wisconsin? 

Dr. Werle: Not a whole lot Tommy, not a whole lot. Not a whole lot up here.

Tommy: There's some wild rice though, right?

Dr. Werle: Yeah sometimes. Sometimes when we get to moving materials you have some volunteers that come with, but yeah, a conversation for later. 

Tommy: That's right, that's right. So like Rodrigo said, we've been very familiar with each other and like I mentioned before, we really just wanted to hit on a few different topics and let all of our listeners kind of, learn a little bit of weed control in a different area and maybe find some topics that Rodrigo is doing some research on up there in Wisconsin that may be beneficial to us down in Arkansas and also vice versa, you know anything that we're doing down here in Arkansas that might be beneficial for Wisconsin growers. So that was kind of the whole point of this since we're kind of reaching the end of the season and getting away from real critical timings for weed control, we can hit on some things that maybe will help us down the road. So one of the first things I wanted to mention at the top of this is, I love the quote from Benjamin Franklin that nothing is certain in life but death and taxes, but I think he missed part of that quote and missed the part that said the fight against weeds in agriculture is also, it's always certain in life too. Because no matter where you are, what crop you're fighting, you'll always have weeds that you're battling as well. So I think in the future we can say nothing is certain in life but death, taxes and weeds. I think that's the addition that we need to have on that quote.

Dr. Werle: I love that idea Tommy. I oftentimes give our colleagues in plant pathology a hard time, right, because they never know how intense the diseases will be, but we know that if we got seeds in that soil seedbank, we're going to have weeds for sure. They're always there.

Tommy: That's right, that's exactly right. And they don't move so it's easy to capture them that's for sure. So the first thing that I wanted to hit on is maybe just a little bit of the variety of crops that we have growing in each of our states. Especially field crops. So down here in Arkansas, we really are heavy in five main field row crops. We've got soybean, rice, corn, cotton and peanut. As far as soybean goes, we have any and every technology you can think of. Liberty Links, Xtends, Enlist. Even a fair amount of conventionals because we have a pretty hefty poultry market and a lot of our conventionals go to the poultry market. Rice is probably our second biggest crop in the state. We're the #1 rice grower in the country down here in Arkansas, so we just have some really good soils conducive to keeping a flood and growing rice and things like that so that is a major commodity for our state. And then like I mentioned, corn, cotton and peanuts all take up some space as well. So that diversity is great to see growing, but it also leads to some unique weed challenges as well as herbicide drift challenges and things like that. What do you have growing up there mainly Rodrigo? What are you working in a lot?

Dr. Werle: Yeah, so again, up here in Wisconsin, we're a dairy state, a strong dairy industry, but we do have a lot of grain crops. We also grow or raise a lot of forage crops. We got to feed our cows here so that's what a lot of what some of our growers do here. In regards to crops I would say corn, soybeans, alfalfa and small grains as well Tommy in that mix, so a quite diversified system where we have alfalfa there in part of that rotation that really helps with weed management because we have a perennial crop kind of growing year round and being chopped year round so a well-established, well managed alfalfa crop can really help with suppressing weeds if you would, so we have a diversity of crops all around the state. The primary crops that our research program works with are corn and soybeans and the soybean crop we also deal with all the various traits or bio-technology we have available. And then one thing I want to point out here, in the central part of the state of Wisconsin, this is where we have a lot of vegetables being grown there. This is where we get a lot of potatoes. We have sweet corn and some other vegetables are grown as well, and soybeans kind of come as part of that rotation if you would. If you're thinking you just described drift there, this is an area where folks are often concerned about drift because they have some really high value crops in that central part of the state where we have sandier soil. So very diverse state from a cropping system perspective. You get to see a little bit of everything. It's pretty neat. 

Tommy: Yeah, that's awesome. So just kind of along our cropping system too, I guess something else we should maybe mention is just the weather patterns a little bit too. So this last week we just got out of a major heat wave that went through Arkansas. We were averaging upper 90's, we didn't quite hit a 100 apparently according to the Little Rock thermometer. I disagree because on my thermometer we were over a 100. So we were pretty hot, we had a lot of humidity, especially when you're talking about flooded rice fields and you're walking through a flood close to 100% humidity a lot of time this summer and a high heat. Now we've cooled off this week, we're back to like the mid to high 80's for highs and things like that, but typically we're talking 90's throughout the summer and very low precipitation throughout the summer. We get a lot of total precipitation for the year, normally somewhere around 55 inches, but often times in the summer it really shuts off and so we're actually, I want to say #3. We're in the top 5 states for irrigation. And we do a lot of furrow irrigation down here and that's because during the summer months we just completely shut off and then we pick it back up in the fall. And in fall, winter and spring we get a lot of our precipitation. So how does Wisconsin differ from that compared to us?

Dr. Werle: Yeah, that's quite interesting. So the both of us when we worked together, the western part of the state of Nebraska, pretty much, I mean a lot of crops, a lot of acres got irrigated and I moved here to Wisconsin in 2018. It's quite different. Irrigation is not much of a thing here. You see more irrigation in the central sands where they have vegetable production and you see a center pivot here and there across the southern part of the state of Wisconsin, but not a whole lot pivot or irrigation systems out there and that's because of the amount of precipitation that we get.  Usually we get pretty decent precipitation. Most of it kind of comes in the spring during the planting season. We do get some good amounts in the summer overall. So usually precipitation is not a concern, however we're going through a very, very atypical year here Tommy. This is my 4th growing season here in the state of Wisconsin and this has been completely different from what I've experienced this past three years growing up here. I mean you can also share your experience if you'd like. But this has been a pretty dry year. Month of July we're already 2-3 inches behind what we normally get, so overall it's been a dry year which is not normal here. Usually precipitation tends not to be a major concern for us and we tend to get a good amount of rain throughout the growing season for the crops that we raise. We usually get more than what we need, especially when we're trying to plant and spray our trials, right?

Tommy: Yep, that's right, we're never happy right? We always either have too much when we don't need it and then never enough when we do need it, so it's just always a struggle. 

Dr. Werle: Believe it or not earlier this year we were complaining because we were spraying our PRE's and we're getting rainfall for pre-emergence activation so we had to slow down for a little bit and that usually does not happen.

Tommy: See we fight that battle quite a bit down here, but yeah that's rare up there, so that's crazy. Moving in from the crops, and kind of a little bit of that background, one of the first things there that I wanted to hit on was just some of our weed differences, our species that we battle or what's most problematic for the growers and those kind of things, because it really changes quite a bit which is kind of surprising considering we're talking about somewhat similar cropping systems. It's a little bit different and honestly the weather patterns are slightly different but it's not like western Nebraska where we came from where it was a dessert climate, much more similar compared to something like that and so it's kind of crazy to me when we put together a list here of our top five weeds, just how different they were. So the top five weeds that I had listed for Arkansas, was 1, I always say 1A and 1B. I mean they're right there battling each other out depending on what crop we're talking about, but it's Palmer Amaranth or Palmer Pigweed and then Barnyardgrass. Those two are easily our top 2 down here that are just constantly, they're basically the Clemson and Alabama of college football. They are constantly in the national championship fighting it out which one's the worst one. Then we get down to 3 and 4 and I group all of the sedges together. We have a real bad problem with sedges in the state of Arkansas. Primarily because of our rice production in that they survive the flood. So yellow nutsedge, rice flatsedge, white margin flatsedge and then umbrella sedge we struggle with in a lot of our acres and I had a few more calls on that stuff this year in soybeans than before in trying to kill some of those in our soybean crop so they're becoming problematic even outside of our rice acres. Italian ryegrass is my next one and that thing has moved up our list of problematic weeds dramatically. A lot of times you think of ryegrass as only being a problem in wheat and we do have a few wheat acres in the state, but it's just gotten to be such a problem early season, burndown ahead of all of our other crops that it's quickly moved up the list. And our resistance in ryegrass has become real problematic because really we have ALS-inhibitor resistance widespread now. Glyphosate resistance ryegrass is very widespread across our state and then right across in Mississippi they've had Clethodim resistance for a little while and it's already jumped the border and is in south Arkansas that we're fighting. So you start eliminating all those options and we really don't have much left to kill ryegrass ahead of our crops. And especially if you start talking about going into a grass crop like corn or rice, if that crop gets up and you still have standing ryegrass, there is nothing POST to kill our ryegrass at that point and so it's there all year at that point. You're dealing with it all year once your crop is up and you haven't killed it. So starting clean, burning it down has been real critical but that can still be a challenge for some other reasons. And then following, my 5th weed and I can bounce back and forth between 2 different ones here, but weedy rice is a real challenge across crops. You know you get kind of volunteer rice or we also have another sub species, red rice that actually is like an actual weedy rice that's just natural in our population, so that's real problematic and then morningglories. Morningglories can be real, real challenging down here as well. But, so I say all of that to be out of our top, let's say 6 weeds there that I listed including the morningglory. You know 3 of those are grasses, 1 are sedges, then the other 2 are broadleaves, so really more heavily grass and sedge related vs broadleaves. I'll let you take over your list Rodrigo, but it's very different from our list here in Arkansas. 

Dr. Werle: I've truly enjoyed learning from your main weeds there because they are different from what we're dealing here in the upper mid-west and after I go through my list here I'm going to have some questions for you because some of your major weeds there are the weeds we keep talking about to our growers that we want to keep an eye on. We don't want them to come our way. But we're going to get to that in a minute. So now looking, corn, soybean productions in the state of Wisconsin, what are the main 5 or 6 weeds? I would say waterhemp has become #1. It has exploded around the state of Wisconsin in the past 5 years. Some people like to say that I was the one who spread it around, but you were here before me. (laughing) It was around here, it just wasn't as wide spread. We've got to the point now where it is everywhere. We travel around the state and it is everywhere, ok.

Tommy: I caught that, that you were blaming me Rodrigo. Point the finger down south. (laughing)

Dr. Werle: Hey, we're not here to judge, right? (laughing) So waterhemp has become #1 here in the state of Wisconsin. For a while folks were trying to get by with a one pass program early POST and burndown with residual in that early POST. And I'm talking both crops, corn and soybeans, and a common program especially where soybeans was. You till the ground, start clean, right. You plant your beans and then at V1-V2 you come with a tank mix of Glyphosate and an ALS herbicide, for instance imazethapyr to have great soil residual activity in it. You hit it at the right time, you have excellent weed control, right. Well that works when you have Glyphosate susceptible weeds, small seeded weeds, that program worked for a while. Once you bring waterhemp into the game, we've done some screenings here. One of our graduate students Felipe Faleco defended earlier this morning, right? I mean he presented some results more than 95% of our populations were both Glyphosate and ALS resistant so that forces a major change into our producers here on how they control weeds. So again, waterhemp has been the #1 all around the state troublesome weed that extended the emergence window. It makes it very, very difficult to control. The 2nd one is giant ragweed. You and I were at Nebraska, giant ragweed in Nebraska behaved one way. It emerges early in the spring and it's done emerging in two or three weeks, ok. During graduate school we did some work looking at emergence window of giant ragweed there and usually most of the seedlings come up before crop establishment, so an effective burn down can help you tremendously for giant ragweed management. Here in Wisconsin it's a different ballgame. You know giant ragweed is the first annual summer weed to start emerging. As soon as the ground is thawing here you will start seeing seedlings come through. Early April, mid-April they are starting to emerge. And if you go to the field now we're talking early August here, if your canopy's not close out there, this thing is still emerging, ok. And once it's up and running it's a very, very aggressive and competitive weed, so that's one of the weeds we are keeping an eye on. We have cases of Glyphosate resistance, we have cases of ALS resistance and we have unfortunately recently found the population showing signs of PPO resistance, especially in food grade soybean systems. Again, we're talking food grade. We cannot use any of the technology that we have now to control postemergence, very, very challenging.

Tommy: Giant ragweed is one of the interesting ones on your list for me too. Kind of like you talk about how different it was in Nebraska, it's very different down here too. You know, we can find giant ragweed very easily in roadside ditches, along woods, all of that kind of stuff down here, but as soon as you get in a field crop situation, there is no one down here that struggles with giant ragweed. You know that is not a problem in any field I've ever been in, but you can find it everywhere, it's just not in our field cropping situations. So again, it's crazy, the geography how much that changes and shifts which weeds are that problematic.

Dr. Werle: That is so interesting from your comment there, because that's how it used to be here in the mid-west twenty years ago, right. It was a weed that was found in the roadside ditches, but it would never invade the crop. But it has adapted to our current cropping systems here. What's interesting to hear the analogy, or you know the correlation that I see is in areas where you have more no till, it kind of tends to emerge in a shorter period of time. Where you have more tillage, it tends to have a more like widespread window which is our case here. So again giant rag is our 2nd weed here. Most troublesome weed I would say in both corn and soybeans. Also a big problem in small grains. Usually small grains do a heck of a job suppressing small seeded weeds like waterhemp and some other ones that I'm going to talk next. Giant ragweed because of that large seed and large seedling nature it can just go through it, so it can be a problem with summer crops but also on small grain or winter crops if you would. The 3rd one down the list is lambsquarters. It is everywhere. The leaf, the seeds last forever in the soil seed bank. And even though we don't have Glyphosate resistant lambsquarters, if you don't spray it right under the right conditions, controlling lambsquarters can be challenging. The 4th one on my list here and I'm going to have 2 on my 4th ones are going to be horseweed or also known as marestail and dandelions. And those 2 weeds are usually present in our no till fields, ok. The other 3 that I just mentioned are present in both, no till and till. Here in Wisconsin we do a lot of tillage. And where we have tillage, fall tillage, early spring cultivations we tend not to see horseweed and dandelion, but where we do not practice tillage, or as our growers start to change into more soil conservative practices if you would, adopting more no till, this is where we're starting to see more and more of these 2 weeds popping up. Both horseweed and dandelion, majority of them come up in the fall or early spring, and they are well adapted to no till conditions. The next one is my 1st grass weed which I'm going to describe which is foxtail and then you have yellow foxtail, green foxtail, giant foxtail. They tend to be everywhere in corn and soybean production here. It's our one group of grasses that we tend to see everywhere and then the last one is our volunteer corn in soybean. Oftentimes people tend to forget about our volunteer corn and then you drive around this time of the year it's evident the fields of volunteer corn is being managed and the fields where volunteer corn is not being managed. So this is kind of the list of weeds that we have here in Wisconsin, the top ones. Now I have a question for you here Tommy and I think the information you are going to share is going to be very, very helpful to the listeners that are here in the mid-west and the upper mid-west. Please share your experience with Palmer Amaranth. Here in Wisconsin we're a dairy state and we bring a lot of cotton seed from down south. We are concerned about Palmer. We have run across Palmer. When we find Palmer here it is already resistant to herbicides. That's my first one for you. Please talk about Palmer Amaranth and how big of a challenge is it for you guys down there? 

Tommy: Sure. Palmer Amaranth down here is just absolutely insane. It is a crazy weed species to have and really I liken it to waterhemp. The battle with water hemp is very similar to battle with Palmer. I always say Palmer is a 9 or a 10 on just being a beast. Waterhemp is literally an 8 or a 9. It's just right behind it. It's not very far behind so I know I've seen some pictures and I dealt with some of it when I was up in Wisconsin on the waterhemp front, just how bad it can get. So I know a lot of growers up there kind of have that feeling too and it's really the same on Palmer, even though we just have that much more competitive ability and seed production and everything else on Palmer. So down here one of our biggest battles anymore now is just the resistance that has evolved in Palmer Amaranth. Kind of like you mentioned with waterhemp in Wisconsin, we have multiple modes of action now confirmed resistant, including some of the stuff you didn't mention. We have Group 15 resistance down here, so Dual Magnum and Warrant no longer work on a couple of our populations down here on Palmer, which is a real loss because that's a big part of our pre-emergence program normally trying to control it. We have quite a bit of HPPD resistance anymore across the state. Laudis or Callisto don't work on it anymore. We actually first confirmed Liberty resistance this past year, so we now have a couple of different populations that are resistant to Liberty, so we're losing another post-emergence option there and right now at this time we're even doing more screenings on potential 2,4-D and Dicamba resistance within our Palmer Amaranth population. And that already has been confirmed right across the border in Tennessee. Dr. Larry Steckel has confirmed that in his state, so if it's not here in Arkansas yet, you know it's only a matter of time. So if you start adding up there, I'm not very good at math, I'm a biologist, but we're down a lot of different sites of action there and we just really don't have much left for control of Palmer, so that's the battle that we're really fighting. And then not to mention you talked about the growth characteristics, the extended germination, all those kinds of things, I have a picture from a couple years ago from the middle of October where Palmer Amaranth had emerged and threw out a seed head in like two weeks in October, after corn harvest. Again, the seed production is not huge there, but if you've got a thousand seeds you've got a thousand more plants going back to that seed bank just because it emerged that late after our corn harvest. That's crazy. So that's part of the problem there, you know the fact that they can produce so many seeds, the seed banks are so full down here, that's the struggle we're living in right now with in trying to manage that thing. And like I mentioned too, we have a diverse cropping system but a lot of times with our rotations, we end up in similar environments, so a lot of times soybeans and cotton might be grown together and those herbicides generally are very similar. You got broadleaf crops you end up with broadleaf herbicides, so if you're rotating between soybeans and cotton you end up in kind of the same pattern. Now corn a lot of time we'll get in that rotation with cotton which that helps a lot. We can mix in Atrazine, or we can add in a few other things there, so that kind of helps if we get corn into the system. But we can kind of get caught in that crop rotation factor too where even that doesn't necessarily help us if we're not rotating amongst the right crops and diversifying those herbicides up. So that's been our challenge on the front. Like I said Palmer is just a beast, but then along those lines too, the grasses are just absolutely insane for us down here too. We talked about it. You know I had 3 to 4 grasses basically listed on my list and you had your one and really that to me is a factor of kind of our rotation and what we have to use to kill some of our different species and so with rice, we end up with barnyardgrass as or #1 rice weed because it is so physiologically similar and it can survive a flood so that cultural practice doesn't help us with barnyardgrass and so we're relying on herbicides and when you build resistance to some of the FOPS we can use and then things like growth regulator, like Quinclorac, we use a lot of Clomazone or Command, we're starting to have some resistance building there, it just builds and builds and builds and then all of a sudden just because of our rice rotation, now we have barnyardgrass that's resistance to 5 or 6 different modes of action, sites of action and then that spreads into our other crops where we can't kill them in those either. So it's just kind of those combinations of our diverse cropping systems, but then also some limited herbicides options in other crops and what we're trying to do to battle it and that just explodes some of those other weed populations when we can't get them controlled and again that seed bank takes over. So that's some of our main challenges with it. I also like you mentioned with the no till tillage thing, that does some major weed shifts as well. We are very heavily tillage involved down here and it's not necessarily deep tillage a lot of times, normally we're just kind of trying to scratch the surface and get that ready for planting again. A lot of times deep tillage doesn't happen down here because we have that hard clay pan and that hard clay pan is great for growing rice because it holds water, right. We can hold that flood but then it struggles to do any deep tillage events and bury some of our seed bank and things like that, so we end up just tilling the top and when you till the top you just bring more seeds around and just constantly cycle. And so we run into a lot of issues on that and it kind of gets to the aspect like you said about why we don't necessarily see as much horseweed down here. We do have some of it, it is a problem in some fields and it seems like it's increasing down here too but it's not near the problem like you observe up there with the horseweed and things like that. And again I think it's just kind of our management systems and the way they kind of work out. Are there other major resistances, reasons that you foresee differences in our weed spectrum that you wanted to discuss Rodrigo? 

Dr. Werle: I think you provided some phenomenal information there Tommy and I just want to do a quick recap here because I bet there's going to be a lot of listeners here from the mid-west and I hope there's going to be a lot of listeners here from Wisconsin paying attention to what you just said in regards to that Palmer. The way I like to start my conversations when I'm talking about Palmer is, hey, you want to get rid of waterhemp? You bring Palmer to the operation right. Because they're more competitive and that's kind of the trend you and I got to see when we were out west in Nebraska for graduate school. When I first landed in Nebraska where my internship, and by the way if you're wondering where this accent comes from this is where I got the accent, the Nebraska accent. Just kidding there. I spent seven years there. Amazing seven years, but when we got to Nebraska I got to the eastern part of the state in 2009, 2010 and at that time my colleagues were starting to do some work with waterhemp, right, because they were concerned about waterhemp resistance in that south central, eastern part. You go back there now years later, Palmer Amaranth has invaded that whole area, so Palmer keeps on marching. It's marching its way, it's moving around the mid-west, but what's different here for us in Wisconsin again is our dairy industry, moving that cotton seed, so we always talk about Palmer to our growers here. Hey you're moving cotton seed, watch for Palmer. Because what are we going to do, we're going to spread that manure back into our fields. And the other one that is just said there Tommy is barnyardgrass, ok and that barnyardgrass here for us, barnyardgrass is easy to control in our corn and soybean systems, but if we bring seeds with the type of resistance you just described there, if we got those populations in here, it's going to become more and more difficult to manage. So again it's important to understand what your bringing into your operation, what kind of weeds are present and pay close attention to how they're responding to the herbicide program so I think this conversation here is just fascinating Tommy. The other thing, some of the old weeds right let's say velvetleaf. That seed lasts forever in the seedbank and here in Wisconsin where we till a lot so we're always moving seed back and forth and that seed is always being brought up. This year for instance it was a dry year, and venice mallow and velvetleaf really like dry conditions so this year velvetleaf is everywhere in the state and everybody is calling saying why velvetleaf? I've been controlling my velvetleaf for the past ten years, why am I still seeing it? Well, research shows that velvetleaf in the seed bank can survive a couple of decades there, so there's your answer. So at the end of the day regardless if you're in Arkansas or here in Wisconsin, it's all about seed bank management and understanding how long those seeds can last in the seed bank, so you plan your management accordingly. 

Tommy: Well I think part of that too. That's an excellent point. It's understanding your weeds and understanding that seed bank longevity and everything else and to tie into that is really our maintenance cleanliness I guess is the best way to put it. Making sure that when we're transporting equipment from one field to the next, we're trying to clean it off the best as possible. We're not spreading things from field to field, because thatÔs the easiest way, especially if we go back to Palmer or waterhemp. Those seeds are so small, in a small little area you can have a thousand seeds and not even know it and you just spread a thousand seeds across your next field with just a small little handful, you know, just right there sitting on a fender or something. And so making sure we try and keep all of that as clean as possible, even when we're harvesting. You know for harvest in the field, we don't turn around on the road and shoot everything out into our neighbor's field or anything else. You know just paying attention to some of those little details can help reduce the spread and then maybe you're only battling it in one field and you can really focus your efforts on that one field and not have to worry about it across an entire farm, those kind of things. I think that plays a huge role too in us being more successful with managing some of these tough weeds, especially when we start getting resistances involved, because that just adds in another whole level of trying to control these things.

Dr. Werle: It's awesome though that you got to this point because tomorrow or the next couple of days that we're traveling to the northern part of the state of Wisconsin and we're going to have what we call a combine cleaning workshop. So we go out there and we talk about how to clean a combine, Dan Smith with the NPM program, you guys overlapped in school Tommy, he'll go and show a grower where the seeds are hiding and how to clean the combine and then we also talk about biology and ecology and longevity of those seeds, how they are spreading. We like to use the paper that Dr. Norsworthy published a couple of years ago, where they started a couple of small fields with a low level of infestation and when they just went with the combine, that spread that weed seed and within 3 years, a few plants lead to a severe infestation in cotton production, so we like to use that as an example, so the hygiene of your systems if you would, paying attention to where seeds are going and being strategic about harvesting the infested fields last, that can go a long, long way for sure. 

Tommy: One other thing I wanted to hit on too when you were mentioning the grasses and barnyardgrass and things like that too, with the resistances that we've evolved, you know it all starts with one. I always like to bring that up too. You know you get focused on using one herbicide over and over because it works great. Glyphosate's a prime example of this. It worked great, you can kill stuff when it's big. It doesn't matter, we just sprayed it year after year, multiple times, it was great. Once you lose one, it becomes very easy to evolve resistance to another. Whether that's because of metabolic resistance or whether it's just the fact that now all of a sudden you're putting more selection pressure on a different herbicide class, right? And so it's like I mentioned, once you get one, it's a slippery slope and you can real quickly easily evolve resistance to more and so like we talked about there in Wisconsin, right now it may not be a big deal but if all of a sudden you lose ALS chemistries, right, that don't work on it anymore, now you're putting an awful lot of selection pressure probably on Glyphosate, well the time it takes to lose that one too it's just boom, boom, boom right down the line. You can knock them off the list and that hurts a lot when you start talking about managing stuff postemergence like that. 

Thank you for joining us for part 1 of this podcast episode where Rodrigo and I discussed certain similarities in weed species that are present across our fields and some of the resistances that we're battling. Please stay tuned as we'll have part 2 for the rest of our discussion as we go into some of our research and some more recommendations for each of our states as far as weed control goes. So thanks for joining us for this episode of the Weeds AR Wild podcast series on Arkansas Row Crops Radio.

End notes: 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.