Weeds AR Wild Series, Season 2 – Episode 2
Title: Make Every Application Count
Date: February 23, 2022
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. And thank you for joining me for this second episode of season two of the Weeds AR Wild Podcast series. This week, I have the privilege of hosting and discussing, basically, how we can get the most out of our herbicide applications for 2022. So, by now, I'm sure most of you have heard that our prices for herbicides have significantly increased from last year. You know, availability of several different herbicide options are very low. And so, we're just running into a lot of challenging aspects to this year's weed control strategies, or programs, because of these influences on, you know, herbicide availability and cost. So, I really wanted to discuss today, you know, just different things that we can do to make sure we're setting up each herbicide application for success, right? That we're not leaving stuff on the table. And so, a lot of these things might seem like little things. But again, if we have a lot of little things, we can set ourselves up for success, or if we have a lot of little things go wrong, we can set ourselves up for failure. So, I just kind of want to hit on a few of these things today. 

Now, one of the first things I wanted to hit on, too, is the way that we can make our applications the most successful really at first doesn't even have to do with the application. It has to be some of the programs that we put it in. And so, one of the first things that I just needed to highlight before I even get into the application talk, is that we really need to be making sure that we're using residuals this year. We're getting them out timely. We're using multiple modes of actions, and that we're overlapping those residuals. And so, I just wanted to highlight that right, first thing off the bat.  We want to put ourselves in a best-case scenario first. And so, if we can use a lot of these residuals and multiple MOAs and overlap these residuals, we're going to set ourselves up for success from the application front anyway. Especially from a post emergence application front, because we should have less weeds up. They should be smaller when we're going out there for a timely POST and all those kinds of things. So, if we can put ourselves in a good situation, it just helps all of our applications downstream. Now, following that, there are a handful of things I wanted to talk about today, on the application front. A few of those things I'm going to hit on include mixing order, some of the adjuvants that I get a lot of questions about. I'm going to get into a little bit on nozzle selection and some importance there, and I will hit on, at the very end, just a little bit on the aerial application side as well. But let's just jump right in. 

The first thing I wanted to discuss was on the mixing order side of things and just something that we should be paying attention to right on the start end of when we get out there to try and make one of our applications. So, the best couple pieces of advice that I can give you on mixing order is first and foremost, we want to make sure that our main spray tank on that sprayer has at least a quarter full of the water (or total volume by the end). We want to have at least a quarter of that full load of water in that tank before we start adding chemicals. So, we need to have at least some water in there that we can start mixing into and just give us a base to start basically diluting our products down in that sprayer.

We want to make sure to have that at least a quarter full of water. The next thing, when it comes to our mixing order, if you, the easiest thing that I can tell you to remember is the WALES sequence.  W-A-L-E-S sequence. And so, what that stands for is the W is for wettable powders or our dry products. Those should be the first things to go in the tank. After that, the A stands for agitation. If you have any of those drys, we need to make sure we're all in that water agitating it really well to get all of those in fully into solution. Following the A of agitation, we go to L, which is for liquids and micro encapsulated materials. So a lot of our, you know, a lot of our liquid type formulations can go in next. Following that E is for our emulsifiable concentrates. So we want to get some of those products in towards the end. And then the very final thing that should be going in that tank, the S is our surfactants and oils, right. So if you can kind of remember that WALES method, that gives you a rough idea. The dries go in first. We want to agitate those for sure, then start adding the liquids and then the emulsifiable concentrates. And then finally the surfactants (or oils). 

Now, one big thing that I wanted to hit on, because I've had a lot of calls on this, you know, in the past year or so is, you know, mixing products together before they go in the tank. Right? So straight formulated products, mixing those together before they actually get into the big spray tank, the main spray tank. And that's a real, you know, it's a big thing we don't want to do. We do not want to mix concentrated products together before we start mixing with water. And so, this comes into a problem, really in a lot of situations, if we're using an injection or an inductor tank. Right? We don't want to mix multiple products in that small inductor tank before we start flushing it into the big main spray tank. So if we have those types of systems, and I know this gets to be, you know, an issue because it's not as efficient or timely. Right? But we need to add one product into that inductor tank first, flush the system with water, get it all in.  Then add the next product, flush it with water, you know, get it into the main spray tank and etc. and keep agitating the main spray tank. Now, although that seems less efficient - in the long run, you're going to have less compatibility issues with that. You're going to have less problems with efficacy and antagonism things. And so overall, it's going to be a much better method for you to get the most out of your applications by splitting up each one of those individual active ingredients and getting them into the system separately. We just can't be dumping those things together first before they start getting agitated with water. So those are the main things, on mixing order, I wanted to highlight - as far as what the order goes and then that we're not mixing those formulated products together before they actually get into (and diluted down into) our main spray tank with all of our water. So make sure, that we're following that kind of pattern. 

Now, outside of mixing order, the next thing I really wanted to hit on was adjuvants, and I get a lot of questions on adjuvants each year and, it's really tough to answer adjuvant questions, because of the millions of possibilities that are out there. And each one, you know, is a little bit different proprietary material, the inert ingredients might be a little bit different, they might be a different combination of types of adjuvants. And so that can be it can be very difficult to talk about those in general terms. Now overall, I'm going to try and do this generally, you know, adjuvants have different purposes that each one of them can play. So we have, you know, different things that might affect our water. Like our water conditioners, our defoamers or things like that, we have adjuvant products that are stickers or spreaders or, you know, drift reduction agents, penetrants, all those kinds of things. There's a lot of different, you know, factors why adjuvants should be selected and put into a spray tank - because they have different roles that they might play. So you really kind of need to know what each of those roles are for different products and, when you might want to select one over another. 

So, I'm going to start off with water conditioners first. And the reason I'm going to start with water conditioners is because, if you are really using water conditioners for what their purpose is, which is basically to assist with hard water, those should be getting mixed in the tank first before you add in any chemicals whatsoever. You want to get your water conditioners in the tank first. And now the reason for that is, is because they basically act as a substitute. So what's going on with hard water is that we have positively charged cations in our water. Right? So think of things like iron, calcium, magnesium, sodium. Those are really the bad ones. They're all positively charged floating around in that water. Most of our herbicides, especially things like glyphosate, glufosinate, tend to be negatively charged. And so it's just a it's just a basic electrical principle right? You get a positive charge and a negative charge in the tank they attract. And what it does is if we just throw our negatively charged herbicide in there, they attract, they get bound up, and they're not free to do their job. Now, the purpose of the water conditioner is it acts as a substitute. You throw that in the tank first, it's negatively charged. It goes after those cations, those positively charged cations, and they tie each other up. Then we add in the herbicide after that, let's say glyphosate, and it's in the tank. And now there's not as many free cations flowing around, to tie it up so that herbicide is more available to do its job. Right? And so that’s the whole purpose of this, is that we can act as a substitute. If you put the herbicide in first, you’re not getting that substitute effect because the herbicide’s already getting bound up before that conditioner ever even makes it in the tank. So kind of think of it as, you know, like our when we're on the airplane, right. And we hear the, you know, free to roam about the cabin. That's what the whole point of the water conditioner is, is it takes the place of the herbicide and ties all those cations up. So the herbicide then is more free to roam about the cabin and do its job. And so that's why we want those to go in the tank first. And especially we want to be using water conditioners in areas if we've tested our water where we know we have high iron calcium, magnesium or sodium. 

Now, we've done a survey across the state, and I can tell you there's been a few places in the state where we have some very hard water. We have some high pH things like that. Waldenburg and Weiner area comes to mind. There is some very, very hard water up there, you know, and so just being aware of that and potentially adding in something like ammonium sulfate or AMS can be a big benefit to be that substitute, tying up those cations and allowing the herbicides to do their job. Now, outside of water conditioners, like I mentioned, there's several other different kind of classes of herbicides and what they're you know, what their main purpose is.

So the next thing I really wanted to hit on was methylated seed oils or MSO. MSOs tend to be the best adjuvant for retention on the leaf surface. So there's some data out there that has shown that if you use an MSO, you can normally get more of your herbicide to stay on a leaf surface and the other positive to a methylated seed oil is it makes sure to burn through a waxy cuticle. So if we have a weed that has a very waxy cuticle, it helps to burn through that to make sure that our herbicide can enter the plant and then move throughout the plant if need be. Now there's a couple of downsides to MSOs. Typically, they tend to be more expensive, so we're going to have to you know, spend a little bit more money on those. And then also if we get a little bit high rate of MSO or our, you know, herbicide is a little bit hotter, we can cause some pretty severe injury to some of our crops. So, we have to balance that out a little bit with something like an MSO. Now, outside of an MSO, we also have crop oil concentrates or COCs, and we have surfactants that most people are familiar of. With a surfactant, the one thing I'd like to point out is make sure that you're getting a good high quality surfactant. You know, that it's at least an 80-20 mix. You know, 90 tends tend to be even better. But if you can at least get an 80-20 and it's not less than an 80% surfactant, that's always better than some of those lower ones. So pay attention to that. But with crop oils and surfactants, they tend to be about equal as far as retention goes, it's a little bit less than what an MSO can retain on a leaf surface, but it's still pretty good. And then between those two, they retain about the same amount on a leaf surface. Really the difference between those two boils down to kind of what weed we were going after and what leaf surface we're dealing with. So again, the crop oil part, because it has an oil, will burn through some of our waxy leaf surfaces, whereas a surfactant is really just going to help us get it to stick to that surface and help it, you know, basically move into the plant because you get more retained on the surface, but it's not actually going to affect the cuticle at all.

Now, for most of our weeds that have, you know, not really a waxy surface or they're a little bit hairy surface, a surfactant does a great job for us. But if we're thinking of things that have a real waxy leaf surface and the one that to me that comes to mind is yellow nutsedge, it's got a real waxy leaf surface to it. You're going to want something that can burn through that wax a little bit and allow our herbicides to get in there. That's one of the reasons why if you look in the M44 or you talk to Gowan, you know, with Gambit, Permit, Permit Plus our recommendation is to use crop oil concentrate or MSO and it's because they have that burning power to burn through that waxy cuticle and make sure that herbicide is getting into the plant to be successful at killing it out. Right?. So again, just you know your weeds a little bit there if you're really debating between an MSO or MSO-COC, or a surfactant, if you don't really have if you're going after something like Palmer Amaranth, you know, it really doesn't have a super waxy leaf surface, a surfactant would do just fine. Right? So that's kind of what those oils are for versus a surfactant.

Also, I just need to say, you know, make sure that you're reading labels. You know, a lot of those herbicide labels have gone through some pretty extensive testing. And so if they have a specific recommendation as far as a let's say a nitrogen source that needs to be in the tank, or you should use a surfactant over an oil or an oil over a surfactant one way or the other, you know, pretty much heed those directions because those are normally, you know, been through quite a bit of testing. That's pretty good advice to follow whatever their number one recommendation is. And so read and follow those labels or look in our MP44 publication for some of those recommendations because they've been vetted and that's why they're recommended. Now, the final thing as far as adjuvant goes that I wanted to hit on is remember to do a jar test. If you're trying anything new or you're trying new combinations in a tank mixture. There's just so many millions of combinations out there when we start talking about all the different adjuvants, the different herbicide active ingredients we've got the different potential combinations that we're coming up with and take mixtures that we can just never test all of these things. And so the big thing that you want to do is if you're doing a brand new combination of those things and you're a little bit concerned, you know, perform a jar test, make sure you don't have any incompatibility issues. And then the final thing I can tell you is just watch what's coming out of the sprayer. You know, whoever is operating our sprayer or applicators you can see if something changes coming out of that back of the sprayer whether it seems to be, you know, clumpy clogging it's dripping a little bit, whether it seems to be drifting more whether the patterns just don't seem to be fully, you know, fanning out completely. You can notice small little changes just with your eyes. And if you see something, you know, flag it, mark it down. Have a discussion with either, you know, whoever you're working with, the farmer, the consultant, whatever, and just try and come up with a different plan of action on the next go around. Right? And let’s mix something up either. Maybe it's a nozzle effect. We got to change our nozzle type. Maybe we got to try a different adjuvant. Maybe we just don't do this whole combination again that we have because more than likely there is something happening, but we probably don't have enough data to fully say exactly what's going on. But if you see something with your eyes that something just looks off coming out of the sprayer, there's a very good possibility that that's completely the case. And we just don't know what it is. And we just need to kind of change up that combination, whatever it might be, and try something a little bit different to make our next one a little more successful. So that's really the best things I can tell you on the adjuvant front is, like I said, watch out for incompatibility issues when it comes to, you know, different combinations and then make sure we're just watching what's happening out of our sprayer so we have a better idea.

Now, as far as the next thing I wanted to get into is our nozzle selection. So we've covered mixing order, we've covered adjuvants The next thing I really wanted to hit on is our, our nozzle selection. And to me, nozzle selection is probably the most important thing that we can do on a sprayer to get the most out of each application, whether it's reducing drift, increasing coverage, you know, just making sure that we're, we're putting our best foot forward. It all comes down to our nozzle because that is the last point of contact before we turn over our herbicides to the biological world to try and do their job in real world settings. Right? That's the last point of contact where we have any kind of management over what's going to happen to our herbicide application. So it should be the, you know, the most critical we should spend the most time on that point because that's our last point of contact where we have any chance of influence in this final herbicide application. So when it comes to nozzle selection, the number one thing I preach every time I give a talk like this is that to me droplet size is much, much, much more important than spray volume. Now, spray volume is important and I'm not you know, I'm not saying don't worry about spray volume whatsoever. But droplet size is the much bigger player here as far as us getting coverage, as far as us getting better weed control at the end of the day. If we can appropriately select our nozzles for whatever applications we're making, that's what we need to do. We need to pick the nozzle that's going to put us in a good situation on the droplet size front. Now, I'm typically the type of guy that I like to go to the middle of the road nozzle right where I can do most of my applications on.  If I'm sitting at like a coarse spray you know, it's a little bit bigger than what, you know, the old XR flat fans used to be or even the TTs used to be, and we can get some drift reduction out of it, but it's not too big that we just completely lose our coverage from that droplet size. So I really like to be sitting in that coarse range, if I can be. It just kind of gives us the best of both worlds, almost. Now, I do realize for some products, you know, we're pigeonholed into larger droplets sizes. So things like, you know, dicamba, we have to have a large droplet size to follow a label for the drift reduction aspect. That's where spray volume can really help us out because if we're forced into using a larger droplet size, we got to increase coverage in some aspect and the only way to do that then is to increase volume. Right. What I would say is if we can get a good middle of the road as far as a droplet size nozzle and we're running at, you know, 10 to 12 GPA, maybe 15 for certain things that should be more than enough for most of our applications. But then once we start having to increase our droplet size, we start talking about the really large droplet size nozzles that we need, for dicamba applications. There, you really want to start pushing up our ground rig spray volumes to about 20 GPA to make up for that huge size where we just can't get as much coverage.  Okay?

Now as far as nozzles go to me, we're going to have to get at least more than one set.  We're going to have to have at least two sets of nozzles on our spray rigs to really truly be successful. This depends a little bit on what we're operating, you know, the conditions were operating in and what we're spraying and things like that. But I've got three sets down that I'm going to talk about. And again, this could be a little bit hit or miss, but to me you're going to need at least two of these three at some point. 

So the first set that that I would describe is you're going to need a large droplet size producing nozzle for drift reduction, especially if you're operating in the dicamba systems. You know, they have a very specific list of nozzles that can be used and they create an extremely large droplet size. And I don't like that droplet size for any other herbicides that we spray. It doesn't matter what crop we're talking about, it doesn't matter what other herbicide we're talking about. I do not like that droplet size for anything else other than on the dicamba front, because it's a label law and it reduces drift as much as possible from the physical standpoint in that system. So, you're going to have to have that nozzle basically on its own to spray the dicamba system. 

Then following that, I really would like to get a midrange droplet size, like I mentioned, you know, coarse spray roughly, because that whatever that could be, that gets me a coarse spray. I basically can get better coverage, but I still have some drift reduction capabilities. Now, the types of nozzles I'm talking about, there are things like the AIXR from TeeJet, the TDXL from GreenLeaf. The 3D nozzle is not a bad nozzle from Hypro in that range.  The MR nozzle from Wilger is a good one, especially for the pulsing systems that happens to be kind of in that mid range. So there's a variety of options and that's really where I would want, you know, the bulk of my applications going out. 

Now Finally, after those two sets, the third set that I would really almost say that we probably need in a lot of situations, is it's really just a second set of  one or two of those. That's the exact same type of nozzle. But it's a different size, right? It's a different color. And the reason that we probably need a different size or different color is because we're going to have a range of spray volumes that we want to operate at or a range of sprayer speeds that would be that we want to be going at. You know, and if we have one set size, we're kind of stuck into what volume and what speed we can travel. Otherwise we drastically have to change one or the other if we're going to change volume or speed significantly. 

Now just to help kind of illustrate that, I did something, you know, a basic little calculation that I wanted to talk about. And so in this example calculation, let's say we want to operate at ten gallons per acre, we've got 20 inch nozzle spacing and we want to travel 20 miles an hour. If you run through the little gallon per minute equation, that comes out to each nozzle needs to be giving us 0.67 gallons per minute to operate at 20 miles an hour and get us ten gallons per acre. Now at 0.67 gallons per minute, we could be operating either in 06 nozzle which is a gray nozzle at 54 psi. And this is theoretical, this would change a little bit in the real world, but this gets us really close to where we're talking about. We could operate an 06 or a gray nozzle at 54 psi and get our output. Or we could select an 08 nozzle, a white nozzle, at 31 PSI and get our output. Now both of those situations would work pretty good. I don't see too much trouble at all in that situation with either one of those nozzles operating at 50 or 30 psi and traveling at that 20 miles an hour. We can get our output pretty easily. Now the problem comes in, if we want to all of a sudden decrease our speed. You know, we get into an area where we can't travel that fast, we're hitting the headlands, whatever. If we have to slow down to 12 miles an hour. And so we still are 10 GPA, 20 inch spacing, and 12 miles an hour - now our output needs to be 0.4 gallons per minute. And if we are still operating with that 06 nozzle, that 06 nozzle has to now drop down to 18 psi for us to get that output. And if we're at the even bigger nozzle, that 08, we have to drop all the way down to 10 PSI for us to get that output. And, both of those pressures are pretty much well below the limit of what nozzle manufacturer recommended pressures are. And so they're not going to be forming a good consistent fan. They're just not going to operate at their best capabilities. And so, we're running into issues simply because we don't have these correctly sized or we're running into issues where we really needed another set of nozzles. So like I mentioned, you know, I really almost think if you're going to operate at a slower speed or you're going to change your volumes - you really need to use this equation into your strength and pick out a couple different sets of nozzles that give you the best of both worlds. Where, one, you can be either traveling fast, or one you can be traveling slow, or again, one might be your high volume nozzle and the other one would be a low volume nozzle - or something like that. So again, nozzle selection, that sizing is really, really key to make sure that we can travel the speeds we want to travel and get the output that we want to use. And so we got to properly size our nozzles up front as well as select the correct type, you know, to get the droplet size that we want. So proper sizing and proper selection of droplet size is really critical when it comes to nozzles. And we can, you know, we can be very successful here or we can quickly mess up an application through that nozzle selection. 

Now, the final thing I just wanted to hit on briefly is to talk about aerial applications real quick. You know, aerial applications, although they're drastically different than ground applications - when it comes to really optimizing them like we're talking about this year, a lot of the same principles are at hand, right? When we're mixing, we want to make sure we've got good agitation. We've got a lot of water in that tank. That we're mixing into. Adjuvants is the same way we want to follow, you know, use the same principles on adjuvant front in the same mixing order, things like that. And then we want to be appropriate in our nozzle selection and other application parameters and make sure that we prioritize droplet size, again. You know, the droplet size is critical for making sure that we can stay on target, but also get good coverage. And so, if we can select nozzles and different application setups, whether it's deflection angles or flight speeds or things like that, to help generate a specific droplet size, that will go a long ways and helping our aerial applications out as well.

I also wanted to hit on that more spray volume does not always mean better coverage in weed control. Just like on the ground rig side, more volume does not always mean better, right? It's more of a droplet size effect, and volume helps kind of on the back end. But I will say, that having a little bit higher spray volume does help us manage a little bit more risk, right? If we're at a real low spray volume, we have really small room for error. So I'm not a huge fan of 3 GPA, even though 3 can do a very good job. But I will tell you, I'm not a huge fan of having to go to 7 for everything either. If our aerial guys out there can give me a truthful, honest 5 GPA, that is definitely a winner for most applications in my book - and I would be very happy at 5 GPA. So for my aerial guys out there, that's my big push is that if we can get to 5, I think, and a truthful five, that's really a win in my book for most of our applications. Now, the last couple of things for our aerial guys out there, we really need to know what our effective swath width is and make sure that we're getting proper overlap on every pass back and forth. And we need to make sure we're flying consistently. And I know that can be challenging with wind, you know, forcing our plane around and things like that. But if we can maintain a consistent height for every, you know, every pass, if we can maintain a relatively constant speed for every pass, you know, that's really what we need to do to make sure that overlap and everything else is very you know, precise on every single pass throughout that field. So that's a big thing. And then the final thing that I can just tell you to watch out for and this is challenging as far as managing it, because we just get into situations where we need to spray and we can't really change which direction the wind's coming from. But if we know we're flying in a crosswind environment where that wind is, you know, coming to us at the side, we're not flying into it or away from it - we can have some different things happen with our spray overlaps because of these crosswind effects. Where, you know, our finer droplets in our spray will travel farther downwind. And when we come back to overlap, we're not getting the typical overlap we expect. You know, a typical spray pattern is kind of that bell curve shape. Well, if we get a crosswind, we end up with a skewed distribution pattern. Basically, where we get a long tail out the side, and we just might not be getting the same overlap or we're getting different levels of coverage and we can end up with some streaking and more crop injury because of just this crosswind effect as well. So, I just wanted to throw that out there for our aerial applicators too. You know, just make sure to watch out for some of those crosswind effects or keep that in the back of your mind at least that might be playing into some problems as well. 

But overall, I just wanted to highlight, you know, let's all have open conversations amongst us, whether it's, you know, consultants, farmers, applicators, whoever it is. Let's all have these open conversations, chat about what we're seeing, chat about what's being problematic and those kinds of things. And hopefully we can all work together and have a successful year by the end of 2022. That's the biggest thing I can ask for this year. We all just have a, have an open talk and we figure out stuff together, because we're all in the ag world and we just need to work together anymore to survive - especially in a year like 2022 is going to be. 

Finally, with that, that pretty much hits on all the topics I wanted to cover today. I did just want to say thanks to all of our Arkansas Commodity Board funding for contributing to, you know, the research that I described today or, that drives all of our recommendations - as well as for helping to provide Extension opportunities such as this Weeds AR Wild podcast series. So, you know, thank you for all of that funding from the commodity boards. I also need to thank the USDA National Institute of Food and Agriculture and the USDA Agricultural Research Service, as well as United Soybean Board and the Take Action Group for additional support there. That helps my program conduct research and allows me to do some of these extension events as well. Finally, if you haven't signed up for our text service, I wanted to mention this. Please sign up for our extension specialist text service. All you need to do is send ‘weeds’ so w-e-e-d-s, weeds to (501) 300-8883 and you'll opt into our service. This text service, you'll receive timely Arkansas weed science updates directly on your phone. It's normally, you know, 4, 5, or 6 text messages a month. Nothing too major, but it just gives you a quick update to say, hey, you know, here's a new blog post. Here's a new podcast. Here's updates that we're seeing in the field. Check it out. You know, if you can get those updates right on your phone, and have some timely information from us, it'll be right there at your fingertips. So with that, I appreciate all of you all for joining me on this week's episode. Look out next week, Dr. Jason Norsworthy will be the host next week to discuss a new weed science topic. And I just wanted to wish y’all the best for a 2022 growing season and hope everyone’s season is gearing up positively so far. So, thank you and thanks for joining us for this episode of the Weeds AR Wild Podcast series on Arkansas Row Crops Radio.

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.