Weeds AR Wild, Ep. 19: Herbicide Drift, Checking Labels, and Staying Clean from Weeds (7/7/21)

Weeds AR Wild podcast series, S1, Ep 19. On this episode of the Weeds AR Wild podcast series, Dr. Tommy Butts discusses recent herbicide drift calls and widespread off-target damage, the importance of checking herbicide labels, and a few final recommendations for finishing the year off strong to keep fields clean of weeds.

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Title: Weeds AR Wild, Ep. 19: Herbicide Drift, Checking Labels, and Staying Clean from Weeds (7/7/21)

Welcome to the Weeds AR Wild podcast series as a part of Arkansas Row Crops Radio. My name is Tommy Butts, extension weed scientist with the University of Arkansas System Division of Agriculture. Thank you for joining me today and I just wanted to say good morning, or good afternoon, or good evening, wherever you’re listening, whatever time you’re listening at, thank you for joining us today for this episode. Episode 19 actually of our Weeds AR Wild podcast series. Today I’m going to be talking about several different things, primarily as we’re getting later in the season, especially towards the end of our weed control portion of the growing season. So I just wanted to hit on a few topics to watch out for here towards the end of the season and give you a few tips moving forward and then just kind of an update on our podcast series moving forward. 

So the first thing that I really wanted to kind of touch on today was herbicide drift. And so all of us weed scientists here at the University of Arkansas have gotten many calls over the past couple weeks dealing with herbicide drift and the repercussions of that drift and what symptoms are and all those fun kind of things. So I wanted to hit on a couple of main ones that I have gotten phone calls on. 

The first one that I’ve gotten phone calls on is glyphosate drift onto rice. The one thing I really wanted to mention on this front is that it is a very dangerous time period for glyphosate to be drifting and hitting our rice crop. Primarily because a lot of our rice is entering reproductive stages and a lot of it is at flood, we’re starting to hit that half inch internode, all those kinds of things. And that is the absolute worst time for glyphosate to hit our rice crop because it immediately gets dumped into the seed head. And at that point we get shortened flag leaves, we can get parrot-beaking on our seeds or even blank out entire seed heads, we also can blow that seed head out the side of the rice plant and all of this can lead to either harvest inefficiency or yield loss to a large extent. Now we can also see some visual symptoms typically with this and that includes buggy-whipping of those rice plants, crimped leaves, they can be a slight yellow color, all those kinds of things and so this can be a really detrimental aspect at the stages that we’re entering into with our rice plant. So the big thing I wanted to mention there is just we have to be careful if we’re applying glyphosate next to our rice fields. You know we still need that to go out on a lot of our soybean and cotton acres to manage grasses and other things, but we just need to watch what we’re doing, we have to be careful, make sure were doing all these drift mitigation practices to make sure that we watch out and don’t let that glyphosate hit our neighbors rice fields because it will not be pretty. 

From there the next herbicide drift that I wanted to talk about that has really blown up over the past couple of weeks, and maybe you’ve heard some reports, maybe you haven’t, but I just wanted to give an update on it here. Dicamba injury has really swept across the state in a lot of our soybean acres. The first thing I did want to mention with Dicamba just as a reminder, we are past our cutoff date officially now in the state, so June 30th was that cutoff so it is officially illegal to apply anymore Dicamba in the state. But along those lines like I mentioned in the past couple of weeks we’ve had a lot of phone calls come in, a lot of pictures, a lot of field visit requests to come look at Dicamba damage. It’s very wide spread at this point, primarily a lot of the counties that I’ve been hearing reports from include Poinsett, Cross, Lonoke, Prairie and Arkansas counties, and they have a lot of landscape damage, but it’s also evident in several other counties including Chicot and Desha, Lincoln and then a few other scattered counties here and there as well. At this point I did want to mention, specifically reported to me, so I mean this is not counting Tom or Dr. Norsworthy or anyone else, this is just strictly reported to me from county agents I’ve talked to, from consultants I’ve talked to, farmers, all those kinds of things, and all the fields I’ve walked. I’m currently estimating that we have a minimum of 200,000 acres of soybeans, just strictly soybean affected from Dicamba damage across the state. Again that’s just me, that’s not counting everyone else, and a lot of acres are probably not reported and everything else. 

Now also I wanted to mention all our research stations in eastern Arkansas have been hit at least once, including Keiser, Pine Tree, Marianna, Stuttgart and Rohwer. They have been damaged and documented with the Plant Board to have Dicamba injury. So again, widespread Dicamba damage especially in the past couple of weeks that have really popped up hot and heavy in a lot of areas and it seems that we just get more and more reports every day. So just be on the lookout for those symptoms. The symptoms have been consistent of a cupping. The patented cupping symptoms that we’ve seen, the cupping is very, very indicative of Dicamba damage. We can get some cupping out of potentially Facet. But normally it takes a much higher rate of Facet to cause that symptom, so unless we’re right next to a rice field, more than likely it’s not Facet causing the injury, especially if it goes across the entire 80 acre field or larger. Normally Facet cannot spread that far and keep causing that cupping symptom. If it goes across and it’s even across that entire field, that’s normally signs that it’s Dicamba damage. Again when it comes to yield loss and those things, we don’t have a good way to estimate yield loss. I will say a lot of the fields that I’ve walked, I do expect at least some yield loss to occur simply because of the timing that a lot of the beans I’ve walked have gotten hit. A lot of our research shows, and a lot of the research across the country shows, that if soybeans get hit right at that late vegetative, early reproductive, so we’re talking that R1 growth stage, that almost always they will exhibit some kind of yield loss, no matter the rate that they’ve been hit with. And that’s a lot of the soybeans that I’ve walked, they were right at the R1 growth stage when they got hit, so I fully expect there to be some yield loss on those acres. Again if it’s earlier vegetative or later in reproductive, sometimes we don’t see that yield loss and the research has shown that too. At least the amount of acres that I walked all of them just happened to be right at that R1 growth stage which is the absolute worst time to be getting dinged up with a shot of Dicamba like that off target movement. So just be aware of that. There is a lot of injury. The best thing I can tell you as far as all herbicide drift incidents, no matter which herbicide it is, if you have a field subjected to off target movement, please call the Arkansas State Plant Board to document that injury and then have them come out and investigate potential sources to see if they can find which direction or the source that it came from and then as always feel free to call or text me as well and I can give my two cents worth there too. 

Getting off the herbicide drift conversation, the next thing I really wanted to hit on was just kind of an overall summary and this can occur beginning of the year, end of the year, anything like that, but what I just want to emphasize is make sure we’re all double checking our herbicide labels too with whatever we’re applying. You know for example, one tidbit that I really wanted to hit on that I’ve had a few calls on this year was checking to make sure that our herbicides are the same active load. So we may have two different herbicides with the same active ingredient but the active load in those herbicides may be different. So my prime example of this is Quinstar vs. Facet. So both are Quinclorac products, both are labeled in rice, both can do the exact same job, but the difference is Facet is a 2lb of AI per gallon product and Quinstar is a 4lb of AI per gallon product.  So what that means is, is Facet a typical common rate is a quart per acre, with Quinstar, because it’s basically a double active load, really a common rate for that then is 16 oz per acre. 16 oz would be equivalent to a quart rate of Facet, 16 oz of Quinstar would be equivalent to a quart rate of Facet. Now we had a couple of instances this year that guys didn’t double check their labels and they sprayed Quinstar at a quart rate per acre which is equivalent to 64 oz of Facet. That’s a huge load of Facet, the rice didn’t like that at all, it didn’t grow out of it, it was really banged up, so we just really got to pay attention to some of those little things. Like I mentioned Quinstar is an excellent product, it can still do a great job, but we need to be applying it at the specific rate otherwise we run into some big issues there. So double check herbicide labels for things like that. Double check and make sure that if we are using other generics that they are equivalent to some of our brand products as far as potentially safeners used or what kind of adjuvant load that they might have, maybe we need to add in some extra surfactant, maybe we don’t, those kinds of things. Just pay attention to some of those little details because they can really go a long way at our final weed control aspects. Also just as we are getting later in the season with these herbicide labels, the other thing I wanted to make you aware of to double check is the season use limits and the cutoff timing for various herbicides in our different cropping systems. So it’s real important that we follow some of those cutoff timings for either potentially residues in our plant material or for plant back intervals the following year. It’s also important to follow those season use limits again for maybe residuals left in the soil, carryover potential, all those kinds of things. So we really need to observe those label requirements for those as well. And we do have a couple of new publications that can help with that. The MP566, Application Cutoff Timings for Common Herbicides and we also have the MP567, Max Use Rates per Application and per Season for Common Herbicides. So those two publications can be a real benefit, just a quick handy reference guide to provide that information to you for a lot of our common herbicide used across the state and across different cropping systems. So feel free, you can either grab those and download those from the internet, from our webpage or visit with your local county extension agent to receive some physical copies of these publications. So just be on the lookout for those and those can be some quick handy reference guides for some of that information that you might need. 

Now finally the last thing that I kind of wanted to hit on was a few getting towards the end of the season weed control thoughts as far as the 2021 growing season goes for weeds. The first thing I wanted to mention is that if weeds like, especially like barnyardgrass are getting basically out of hand, we’re at multiple tillers, we‘ve flooded the fields and we have only half the plant emerged, seed heads are already coming out, all of that kind of stuff, it’s really probably at that point in time to cut our losses and just save the money, instead of just trying to throw everything under the sun at it to try to kill it and spending sixty dollars an acre on that post-flood postemergence shot, it’s really probably a lot better in the end that we just save the money, we take the loss, we deal with the weeds being out there and probably some of the harvest inefficiencies, but it saves us as far as spending that much more money on a weed control POST program that probably won’t kill it at this point anyway either. So at some point we just have to cut our losses if we’ve got some of those major escapes and in a lot of our fields I think we’re to that point where we just need to cut the loss and let them go and move on and try and fight that battle next year. In other areas where we have younger crops, we really need to be watching our moisture and temperatures closely. We’ve gotten really hot and really dry in a lot of areas and so the best thing I can tell you there is if we can and this is just darn near impossible but if we can try to avoid spraying in the absolute heat of the afternoon is better just because we’ve seen some reductions in weed control especially for things like Clincher and Regiment when temps got above 90 degrees consistently. So if we can avoid spraying in that dead heat of the afternoon, also if we can run water down furrows and get our beds completely wicked across no matter what cropping system we’re in, you know soybean, cotton, row rice, anything like that, if we can make sure we have good soil moisture there that will help a lot for either activating residuals in some of our younger crops or for any of our postemergence products that we’re spraying, it helps with their absorption and translocation in the plant because those weeds are actively growing there, they’re actively moving sugars in water and everything through the plant that move that herbicide better too with more moisture. So again really watch our temperatures and really watch our moisture levels to try to get the most out of our weed control strategies that we can at this point. 

And one final note on the weed control front, let’s not forget about our prevented plant acres or our laid out ground out there either. Again I know there’s a handful of those acres out there and if we can kill those weeds in these fields this year, I know we’re basically throwing money at herbicides on a field that’s not going to give us anything but if we can kill a lot of the weeds out there with burndown herbicides, non-selective herbicides and reduce what’s returning to that soil seed bank it can really benefit us a lot in future cropping system years by reducing the number of weeds that we have out there. So just don’t forget about those fields, make sure that we get out there and get a lot of that stuff controlled too and help us out down the road in the future for more growing seasons down the road. 

So with that, that kind of hits on all the topics that I wanted to hit on today for this episode. I did want to mention that since we’ve gotten later in the growing season here, I think what Dr. Barber and Dr. Norsworthy and I have discussed it and we’re going to start releasing our podcasts by-weekly from here on out as opposed to weekly just because the weed control front is kind of slowing down and we’re moving into other areas of prevalence I guess for this year but we still wanted to produce some information and get some information out there but we’re just going to do it by-weekly now moving forward for the rest of the season. So basically next week, there won’t be a podcast, a Weeds AR Wild podcast but two weeks from now Dr. Tom Barber will be back to host this Weeds AR Wild podcast series and provide that fresh episode. So until then if you have any questions please don’t hesitate to get ahold of me and ask questions. If there’s anything else I can do to help please don’t hesitate to ask and as always I just want to say thank you for listening, thank you for your continued support and with that I just wanted to say thanks for joining us for this episode of the Weeds AR Wild podcast series on Arkansas Row Crops Radio.