Entomology Update 8-18-23: Rice Stink Bug, Bill Bugs, Preventing Boll Damage in Cotton

In this week's Entomology Update Extension Entomologists Ben Thrash and Nick Bateman discuss rice stink bugs, bill bugs, bollworms, spider mites 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.

[00:12] Ben Thrash

Hey everybody, today is August 18th and we're getting kind of near the end, Nick.

[00:21] Nick Bateman

Yeah, I agree. It seems like things are kind of picking up towards the end, though, in general compared to the past two and a half months.

[00:27] Ben Thrash

Yeah. Yeah, that’s right. We got a few things here and there to talk about. Well, what's happening with rice stink bugs, I guess, is the only thing really still left in rice, huh?

[00:38] Nick Bateman

Yeah, pretty much. You know, I did get several phone calls over about the past, I don't know, three days on some of this green rice. As it’s starting to head we are starting to see a lot of stink bugs in it. You know, we got combines, not running all over the state, but we do have some combines moving and a  whole bunch of rice getting drained. So they're going to start looking for green, greener pastures. So if you got green rice, be watching out for them, but you know, that's really about it.

[01:11] Ben Thrash

Yeah. I had a call earlier this week about a billbug on some row rice and some guys were seeing some, you know, white heads up in the top end of the field, Nick, he was asking how much yield loss he could expect from that. And from what I remembered, it wasn't very much with just a few heads. What was the upper end of that?

[01:40] Nick Bateman

So we never from a blank head standpoint, we never really were able to make it correlate to yield loss. As in, it never seemed to totally mean anything from a yield standpoint. And if you look at the way that feedings occur, and it seems pretty targeted from billbugs larvae to where they're feeding on primarily secondary tillers. And I think that's one reason that correlation gets kind of weird really. And it doesn't help you have heads out. But really the only thing we've found that correlates to yield loss is going out there around green ring to half inch and count the number of damaged tillers at that point and 10% damage doesn't equate to 10% yield loss. Normally what we've seen is like a Cruiser, a Nipsit, a fungicide only seed treatment was running upwards of 50 to 60% dead tillers at that timing and then like a Dermacor, Fortenza that was providing some level of control would be reduced down to about 10% in between those we were seeing about a 15 to 20 bushel yield advantage to Cruiser, not the Cruiser, the Fortenza and Dermacor. So reducing the reducing that damage by roughly 50-60% equated to about 15 to 20 bushels. But on the blank head part of it, I mean, yeah, it's going to take a lot of them like in a square foot to really impact yield. But we never could really get that data to separate. So it's kind of hard to say there.

[03:33] Ben Thrash

And what I told him, he said he was seeing some up top and they weren't real bad. I told him I was like, you know, our data showed that that rice was able to compensate quite a bit. You know, we had more tillers on rice had been fed on by billbug compensate for that feeding out there. And that was pretty consistent across there. So anyway, a few blank heads, not too much to worry about. Well, in cotton, I guess you done with rice, Nick? All right. In cotton, you know, we're getting towards that timing, that pretty much anything that's blooming right now is not, doesn't have a really high likelihood of making a full boll. So what we're trying to do is protect those bolls out there. And there's a few worms out in some of this cotton, from what I've seen. And, you know, I've got some pictures and what I've been seeing out in 3 gene cotton will be squares being fed on in the top. And, you know, those squares up there in the top, they aren't gonna do, they're not going to end up making a boll. So it's really nothing to worry about at this time of year. That square fading. And, you know, there's some variability we talked about between how we scout plots and how a lot of times consultants may scout their plots. And you got to remember, on like our 6% damaged boll threshold, we're looking at like all the bolls on the plant. We're not just walking through there and looking for damage bolls and picking every single damage boll  off every plant that you find out there and go on. Well, I found, you know, 15 damaged bolls. That doesn't mean you got 15% damaged bolls out there in the field. You got to take into account all of those that are undamaged. You can't just walk through there picking out every single damaged boll you’re seeing and think you got a lot of damage. You got to take into account how much undamaged fruit you got out there to. So just kind of keep that in mind. I guess that's kind of it on cotton right now. I will say that we did have some spider mites blow up in some of our plots at Marianna, and you remember, you kind of got to protect spider mites until you get pretty close to defoliation. You know, you don't want premature debilitation on your cotto. That can end up hurting some yield.

[06:19] Nick Bateman

Hey Ben, hit on some late season plant bug, stink bug management. You know I know we're up to that the window you're talking about. But let's talk about that for just a second.

[06:32] Ben Thrash

Yeah. And our termination timing, you know, for plant bugs, you know, everything would be double if there's any squares left on them or any blooms that you're trying to protect. You know, on the plant, we're trying to, we're just trying to prevent that boll damage this time of year. So our thresholds double on the plant bugs after you get passed cut out, which everything should be past cut out now and then, I mean, you gotta protect for stink bugs. I'm trying to think what that, what that termination timing is for stink bugs, I think is it 450 units passed out.

[07:16] Nick Bateman

I would assume it’d be pretty similar to boll worm.

[07:18] Ben Thrash

I think it is it somewhere around in there? So you gotta protect for stink bugs a little while longer, but I'm going to want to run something like acephate for stink bugs this time of year to get control of them. And we have a threshold one stink bug per drop and to control, to treat for stink bugs in cotton. And that's just something to keep in mind. You know, you need to be looking for those stink bugs. They can, they can actually really do some damage to bolls. Anything else when they talk in cotton, Nick?

[08:04] Nick Bateman

I don't think so. I just if I'm getting a couple calls on it, that means people are interested.

[08:10] Ben Thrash

Yeah, yeah. Well, we've had a, I guess a decent little looper flight. We've got quite a few now here in our plots at Tiller, you know, we're having some problems. Actually, I put a test out last week, so we counted it yesterday at seven days after application and just plain old Intrepid, you know, Methoxyfenozide. We got these generics out there, TurnStyle, Troubadour. They're performing really poorly. We even put out all the way up to eight ounce rates of regular old Intrepid, and I'm only getting between 30 and 35% control with regular Intrepid in those plots.

[09:03] Nick Bateman

Adding acephate to it didn't do a whole lot either, did it?

[09:06] Ben Thrash

No, I got about I got about a 10% bump and half a pound of acephate to four ounces of Intrepid, I was at about 45% control with that. And then with the diamides, I was between, with Besiege or Elevest, I was between 43 and 48% control with those products. So I would stay away from the regular old Intrepid or the knockoffs or the diamides for control loopers. I think your only options right now are Intrepid Edge and Denim. Those are the two things I would recommend putting out. That's really the only things I hear even out there. But I do recommend putting it out on soybean looper and what about stink bugs, Nick?  I know you've heard a little bit on stink bugs.

[10:04] Nick Bateman

Yeah. And I mean in those plots of yours down there, we watched the greens go from threshold to 2X threshold in four days, it seems like. There's still a smattering of them. But really the calls I got this week are on red banded and having stink bugs right there till the end of the season. So you’re at R7. So you got one brown pod on that plant, which is our termination timing for a red banded. And this will really only pertain to southeast Arkansas and whether or not I should spray and look we did a lot of cage work back in 17 with this and what we saw was that at R7, there's really no chance of injury after that, bar any kind of hurricane type weather come through where we're going to get multiple rainy days and it'll soften those pods back up. With that being said, in 17, we had a lot of loads turned around because they had too many stink bugs themselves in it. We're not in that position, though, this year. There's not really a major concern for that. I think at the moment we have heard from our counterparts down in Louisiana that they're picking up more and more stink bugs and they're moving north and they are going to start cutting in to defoliating beans and they will probably keep pushing into the state some. Now that doesn't necessarily mean it's going to be 2017 all over again, but some of those late beans down in the southeast corner, they may end up getting sprayed. I mean, time is going to tell on you know, it's hard to make a prediction there.

[11:44] Ben Thrash

Yeah. Yeah. But I'll tell you, there are still some earworms here and there. I mean, we got a test out near Sherill, have a few tests out on some late blooming beans. And there's a few out there in some in some soybeans right now. I mean, we had tons of moths up here in that field. And our numbers actually went up from last week. So, you know, keep that in mind if you got some late planted beans, there's still some boll worm around to be found. So keep an eye out for them. And you know, I guess just hitting on sorghum real quick if anybody’s got any sorghum. We had a pretty good population of sugarcane aphids over at our plots of Marianna. They did seem to kind of go down this past time that we looked at them like the populations crash and a little bit on us and our sorghum is about milk stage right now so just keep a look out for them. Of course, we're with a real susceptible variety because we try to get sugarcane aphids so some of these other varieties might be doing a little better. And I hadn’t heard anything on the army worms, you know, Nick.

[13:07] Nick Bateman

Yeah I think that was a little flash in the pan about a month ago.

[13:11] Ben Thrash

Yeah.

[13:11] Nick Bateman

So I mean, even all the signal grass wherever you’re at in the state, you just don't see the burn out look, you don't see them down in there. So I don't know. That's a good thing, though. 

[13:26] Ben Thrash

Yeah, but anything else?

[13:31] Nick Bateman

Not that I know of.

[13:32] Ben Thrash

All right, well, if you need us, call us. My number is 501-517-3853 months.

[13:39] Nick Bateman

870-456-8486.

[13:43] Ben Thrash

Alright, thank you.

[13:47] Intro/Outro

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