Title: Early season row crop insect update (6-3-21)

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

Nick Bateman: Welcome to Arkansas Row Crop Radio. My name is Nick Bateman, extension entomologist with the University of Arkansas System Division of Agriculture. Today I have with me Gus Lorenz and Ben Thrash, both extension entomologist. Today we wanted to talk about some of the early season insect issues and what we're seeing and some things like that. Where we're at with seed treatments. I guess I'll start it off with what we're seeing in rice. So you know over in Stuttgart we've had our rice water weevil plots flooded for about two weeks now and haven't seen any adult activity from rice water weevils up until this Monday and we're starting to see a pretty good population of adults move in there and a lot of scaring showing up. One of our recommendations is if we're going to have to make a foliar application for rice water weevils it needs to be usually within the first seven days after going to flood. Over the past couple of years we've seen this trend of, especially if we go to flood mid May we're usually not seeing that flush of rice water weevils  show up to around the first week of June, it's usually a couple of weeks after. And when it comes to a foliar at that standpoint, considering the weather we've had where the rice isn't growing real well, a lot of it's sickly going to flood right now to begin with, we're still in that window we should probably consider that application, especially if the scaring's greater than 35-40% on new leaf material out there and need to keep in mind too, if you have like a Cruiser or NipsIt seed treatment, we're talking about the rice that's going to flood right now, got planted the first 10 to 15 days of April. It's long gone. We only get 30, 35 days out of those products so that would put us around mid May. Here we are at the first of June. We're not expecting a lot of activity out of that. If you had like a dermacor fortenza seed treatment on there we don't recommend a foliar on top of those. Those products last much longer and they provide much better control of rice water weevils. The other thing we've seen a little bit of showing up in rice and not to a large extent is some defoliation from some army worms. Now we've done work on this the last 4 or 5 years and what we see is essentially until you get up to green ring it takes a lot of defoliation to cause any yield loss. There may be a little bit of delayed maturity but we see no yield loss from 100% defoliation, so down to the soil line for 2 to 3 leaf all the way up to 4 to 5 tiller rice. Once we get around that 4 to 5 tiller stage, 60 to 80% foliation there we can start getting in some pretty good yield loss and some pretty good heading delays. So that's pretty much what's going on right now in rice, so just keep that in mind, keep up with those fields, especially those going to flood right now and keep an eye out for the rice water weevils. 

Gus Lorenz: Right, we haven't seen this trend with the rice water weevils. Was this kind of different than what we've seen in the past? I mean they just pop up maybe a week after the flood's been on and that kind of thing and that's kind of different from what we've seen in the past, but if you've got that seed treatment out there like Cruiser or NipsIt, and it's 28 to 35 days, it's gone, like Nick said. And I really feel like with the growth that we've seen, I mean it's been cold, it's been wet, and the crops in general across all the crops have just really been slow this year and I think that lends itself towards some damage if we don't take care of these insects and this is the same trend we see in cotton, the growth on our cotton has been slow this year and I'll just say this based on the numbers that we're seeing on our samples and our plots, the thrips numbers are outrageous right now. The thing to remember is when cotton is slow and it's not growing off, well it doesn't take nearly as many thrips to cause damage as it does when we got good weather and good growing conditions and the cotton's growing off really well. It takes a lot of thrips to cause any kind of damage but in this situation is where the cotton's not growing good, just a couple of thrips per plant can cause some pretty significant damage. So that's kind of what we're seeing right now and getting a lot of calls from people and there's some questions about everybody's going out with a herbicide, can they tank mix, and where we've seen some problems with the EC formulation, insecticides like Bidrin and Dimethoat and stuff like that, you tank mix that with Dual and Glufosonate and some Roundup and you can get some pretty substantial burn particularly with these days like we've had. All the cloudy cool weather I just think it lends itself towards seeing some kind of burn on those leaves so being careful about the product that you choose and really scouting thrips right now because they are bad all over the state. It doesn't matter where you are. We're getting calls from everybody about the thrips and I can just tell you they're worse this year than they have been for the last two or three years. Don't you think so Ben?

Ben Thrash: Yeah, I think so. And while we can kind of move over into corn. What we're seeing here, we're getting some phone calls on army worms out in corn. Our threshold for defoliation in corn is really high. Our threshold's about three worms per plant out in the corn field and you've got to get into some really late planted corn before you can even see any yield loss from defoliation from corn. Another thing that we're picking up on, people are calling us about, brown stink bugs, brown or green stink bugs out in corn, mostly brown. They're really hard to find out in the corn fields. So if you start seeing a few out on the edge, that probably means there's a lot more out there than what you're seeing. We hear stories about somebody seeing a few stink bugs on the edge of the corn field, then deciding to go ahead and treat and they come back the next day and there's dead stink bugs everywhere. So keep an eye on your corn for those stink bugs. There's not a whole lot going on in beans right now. We're getting some phone calls about slugs. And there's not a whole lot you can do for slugs except there's a chemical out there called Deadline that works really well. The only problem is it costs about $30 per acre and you can't put it out ahead of the rain which is hard to do. You need a few days of dry weather to be able to put this chemical out for it to work. Or if you're in a no till or minimal till situation or in a cover crop situation, you can disk it and that will help once it dries out and everything and kill all those slugs. But there's just not a whole lot you can do for them.

Gus: Yeah a lot of people are calling right now asking about Acephate for slug control. No, no, the answer's no. So, there's just not a whole lot we can do and I think as we continue to increase no till and cover crop systems, I think slugs are going to continue to be a problem and we're looking at some banded applications and reducing the amount per acre to see if we can find a way to improve control with Deadline to kind of lower that cost but right now your only option is Deadline and it's just expensive. Like Ben said it's not going to be something that our growers are real hip to do, so this is a problem that we're going to have to learn to deal with and how we go from here we're trying to find some solutions but right now there's just no answer for the slug situation. You'll hear stuff about putting out pot ash and pot ash is a salt and if hits the slug or they come in contact with it, it may help provide some control but by and large that hasn't been really effective in the past, so just something to keep in mind. I want to talk about the fire ant situation. I had a lot of people call me at the end of last year and the first of this year about fire ants being bad last year and they're kind of wanting to know what they should do for control in row crops. We did some work a few years ago looking at perimeter treatments of Extinguish Plus and got some really good results with it, but I told everybody based on talking to our fire ant guy that we felt like with the winter that we had this past season that fire ants weren't going to be a problem. Well, wrong again. You know anytime you start predicting, you're always wrong. I was told there's only two kinds of people that make predictions, fools and new comers. And unfortunately I'm not a new comer, so. But they are much worse than we expected this year. They've bounced back from this winter extremely well and we've got some areas where fire ants are a concern. We produced a fact sheet about putting out a perimeter treatment of Extinguish Plus just around the edge of the field and it does work extremely well so if you get in that situation, if you want to talk about it, just give us a call. We can share that fact sheet with you or the details of it and save a little money for the grower. It's not very effective to go out there and make foliar applications just for control of fire ants. It just doesn't work. It kills the workers but not the queen, so it's kind of hard to get control without using some kind of long term product like a fire ant bait that they take back to the nest. So that's pretty much it. 

Nick: Before we get off here, you'll want to update everybody on the moth traps and where we're at now? 

Ben: Yeah, yeah that's a really good point.

Gus: The last few weeks we've had some target traps, specific traps in our trap lines both down at Tillar and up here at Lonoke. And we've caught, just this week, we had a trap at Grady that was running over two hundred moths on a 3 day catch. So pretty significant numbers are showing up and I would tell you that the potential for bowlworm issues is quickly coming up and I think bowlworm numbers, here I go predicting again, but I think bowlworms could be an issue for us this year with what our traps are telling us this early in the year to be catching traps with over two hundred moths and a hundred seventy in one night and that kind of thing. That's a good indication that there's a potential for bowlworm problems this year, not to be a baring of bad predictions, but anyway. That's about it. 

Nick: Alright, well thanks for joining us on Arkansas Row Crop 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