Entomology Update 5-31-24: Early season pests in rice, cotton, corn

Extension entomologists Ben Thrash and Nick Bateman discuss rice water weevil thresholds, thrips pressure, corn borers and more. 

Transcript

[00:01] Intro/Outro 

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

[00:11] Ben Thrash 

Hey everybody. Today is May 31st and yeah, not a lot happening out there, didn't seem like. A little bit of stuff here and there. But what's, what's happening in rice, Nick? 

[00:26] Nick Bateman 

You know, for the past, I guess, ten, 14 days I’ve had several calls on rice water weevil and I think we talked about it a little bit last week. Was really kind of curious as we got more flooded if that pressure would stay constant or if it’d go down, but the phone calls haven't slowed down a whole lot. So it kind of feels like we're maybe dealing with a few more weevils this year than we have in the past. A few things around those phone calls, though, you know, folks are telling me they can't find any larvae, but the fields all have been flooded for five, seven, ten days somewhere in there. And just to make everybody aware, those larvae are little bitty until they get, you know, it's all dependent on temperature, but roughly three weeks old, they're much easier to find then. So, I mean, don't be surprised if you're seeing a bunch of adult right after flood not finding larvae. I mean, besides, the adults needing to mate and all of that. The larvae are really, really small until they get, you know, about three quarter the way grown, which takes about three weeks or so. 

[01:32] Ben Thrash 

Yeah. Even when they're like two weeks along, I mean you about can't find them. 

[01:38] Nick Bateman 

Yeah. I mean like when we pull all of our samples to write seed treatments, foliars, all that stuff we use 21 days as a benchmark. It's not always 21, if it turned off good and hot it maybe be more like 18. But either way it's it's it's two and a half three weeks after planting before they're easy to count. But as far as like control options go, threshold type stuff, you know, we have that scarring threshold. Frankly, we're doing some work right now, playing with a sweep net and comparing it to the scarring threshold. I'll go ahead and tell you I don't have a lot of faith in that scarring threshold. Most of this rice that I'm looking at, you know, you got 100% scarring on new leaves going into flood, putting on a new leaf every 2 to 3 days type thing. And the other thing about that scarring threshold is it's it's basically whether it's scarred or not. And to me, what I'd much rather do is go out there, make sure that I've got a bunch of adults. You know, we're doing that work with a sweep net. We got two sites and one year. We got a student working on it. So it's not like we have a bunch of data to back it up, but sort of seems like somewhere around 15 on ten sweeps is is kind of what it looks like the threshold might be. So, you know, that I would take a sweep net out there at a minimum and just see if I have adults. Rice water weevils is one I feel like we do a lot of revenge sprays because we show up, you know, seven days after the water's been on, see all that scarring and decide to spray. But the adults have already mated, you know, laid eggs and their gone. So anyway, though, just, just keep an eye out and I would be out there scouting pretty good right now. Pretty hard for weevils. 

[03:26] Ben Thrash 

That all that’s happening in rice? 

[03:30] Nick Bateman 

Pretty much. Yeah. 

[03:31] Ben Thrash 

Well, in cotton, you know, it's thrips time of year and it kind of sounds like a bunch of the cotton is kind of past that point up in North Arkansas, they were able to get in there and get planted early. And so they've kind of outgrown thrips on a lot of acres from what I'm hearing. But down in South Arkansas, really the thrips calls seem to have only ramped up over this past, I guess probably started last week kind of.  Just because they've been quite a bit farther behind than the northern part of the state. So and remember, look, guys, with all this rain we got in the forecast, you know, Intrepid Edge is probablystill, you know, our best product. Bidrin you know looks pretty good from time to time. But both are fairly rain fast. You know, you got to run a surfactant with Intrepid if you're going out with, if you're going out with that product. Bidrin, you know, if it looks like there's rain in the forecast, even though it's pretty rain fast, I would probably go ahead and add a surfactant in there to try to improve that rain fastness a little bit. If if it looks like there's some in the forecast. Really, the spider mites, you know, it was it was dry up north for a while. And then I think all this rain set in and it sounds like the spider mites aren't as bad as they were, you know, a few weeks ago. So, you know, one positive thing that's come out of this rain, if you were able to dodge any floods and, you know, washed out beds and hailstorms and everything else that I've heard, you know, going on up there right now. Just remember if you're playing ThryvOn we don't recommend treating it for for thrips but that's about that's not all I've got on cotton right now, Nick. How about how about soybeans? Are you hearing anything on soybeans? 

[05:36] Nick Bateman 

Man, we ought to you know, some of these early beans ought to start blooming early any time now. But yeah. And there's a chance maybe that we get some caterpillars in there or some pod worms. Most likely not. I mean, normally, early planted beans, you know, out run them. Don't really deal with a whole lot of caterpillar pest in there, but there is a chance to get some stink bugs in there. And, you know, regardless of planting date, it is not uncommon to see stink bugs get into blooming beans. We're not worried about them. They're seed feeders. They're just kind of passing through until we really start getting some pods with some size on them, with some seed in there. We're not concerned about them. But but no, not really hearing anything. It's been pretty quiet there. 

[06:24] Ben Thrash 

Yeah. Every year we get them calls on stink bugs in blooming beans. And it always seems like if if they go back and look the next week, it's they're gone. They just flew in and were stopping for the day and then they're gone the next week, you know. So, and in corn you know well the calls that I've got I guess kind of been on army worms this past week people have an army worms or something you know defoliating some of their corn and guys don't worry about defoliation in corn you know if it was, outside of anything that was planted in like June, which nobody does really but there's no point in treating corn for defoliators, they don't cause any yield loss. And then on top of that, it's really, really hard to get any kind of control of caterpillars on those, on caterpillars they want. Yeah. Yeah. So, you know, I don't recommend spraying them at all in corn. But you're already think about corn borer, Nick? 

[07:36] Nick Bateman 

No, but it's I mean, I think we mentioned it last time, too. It's time to get serious about getting some traps out or visiting with your county agent. You know, all of them have traps out in every county to kind of figure out, you know, what them populations are doing. I ain't heard nothing on them yet. But but it ought to be coming up on us pretty quick. 

[07:59] Ben Thrash 

Yeah. And just remember, you know, there's European corn borers out there in their southwestern corn borers out there. I can describe them to you, but it's probably just better for you to look up southwestern corn borer versus European corn borer and look at a picture of them. And you'll see the difference between them having those, you know, dark spots on their body on the southwestern versus European corn borers. They've got a lot a lot more prominent or dark spots on them. So that's that's a big difference there. But, you know, if you get some out there in the field and you're wondering why, you know, you hadn't found any in your traps or something like that, it could be Europeans, but it's still it's still early, but just kind of keep them on your mind if you if you're planting non Bt corn. So, um, well, that's about all I get. 

[08:54] Nick Bateman 

Yeah, I think that's about all that's going on right now. 

[08:58] Ben Thrash 

Yeah, well, if you need us, call us my number 501-517-3853. 

[09:06] Nick Bateman 

Mine’s 870-456-8486 

[09:09] Ben Thrash 

Alright, thank you very much. 

[09:14] Intro/Outro 

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.