Insect update and management strategies for fall armyworms and tarnished plant bugs (6/24/21)

Today’s podcast covers fall armyworms in rice, corn, and soybean and defoliation thresholds. We also cover tarnished plant bugs in prebloom cotton.

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Title: Insect update and management strategies for fall armyworms and tarnished plant bugs (6/24/21)

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

Nick Bateman: Welcome to Arkansas Row Crops Radio. My name is Nick Bateman, extension entomologist for the University of Arkansas System Division of Agriculture. Today I’ve got Gus and Ben with me. We’re going to cover basically all the crops and a bunch of the issues going on. I guess we’ll start out with cotton, talk about some of the issues going on there. 

Gus Lorenz: Yeah, so in cotton we’ve kind of transitioned out of the thrips deal. Most of our cotton is past that point right now. It was a heavy thrips population type of year and a lot of damage. What we saw was kind of interesting. I’m getting a lot of calls from other people about, there’d be like, the plants would look good and then like every fifth of tenth plant, something like that would be wrapped up with thrips and we kind of saw that in our plots in all the varieties that we plant and I think it may be just a seed treatment issue where we’re not getting good coverage on all the seeds and that kind of thing, but I thought I’d bring that up because we’re seeing that quite prevalently across grower fields and in our plots and getting calls, so there was a lot of that issue where it seemed like one plant in like five feet or something, maybe two even would have a lot of thrips damage and the rest of the plants would look good, but that I think is an indication that we didn’t get good seed treatment. But anyway, on the plant bugs, it’s a kind of, it appears like plant bug numbers are there this year. We’re beginning, with cotton, hitting about the ninth, tenth, eleventh node, we’re beginning to see some plant bugs, particularly those typical situations that you’re familiar with, like next to corn, particularly corn that’s turning, the silks are black on the end, or if you’ve got a lot of plainscoreopsus, the yellow flower, around the edges of the fields. We swept some plainscoreopsus the other day and it’s just loaded down with plant bugs right now. So there’s a lot of plant bugs out there in the system and so we’re getting a lot of calls, particularly in that cotton that’s like I said is in the ninth to eleven node and they’re hitting treatment level of eight per hundred sweeps on a lot of that cotton and the question we’re getting is what to use and what your options are. Like you got Centric, Vydate and Transform and so the best that we see with Vydate, which a lot of people like to use, because of the nematode activity. You know the best we ever do with Vydate in our plots is about seventy percent control. And in these situations where plant bug numbers aren’t high that’s not too bad. Seventy percent control is not anything to sneeze at and I wouldn’t tell you not to use it certainly because it does work. The other product is going to be Centric or Transform. And Centric, the company doesn’t recommend using less than two ounces per acre and we would agree with that wholeheartedly. You need to be in that two, two and a half ounce range minimum to get control and when it comes to tank mixing and that kind of thing, that’s always a consideration. Be concerned about mixing with a bunch of other products and making sure you get it in solution and going into the right mixing stage to get it where you need it. And if you treat with one of those products, Centric or Vydate, and you don’t get the level of control that you feel like you should get, it may be time to think about changing gears and maybe considering Transform. And another idea where populations are really high next to corn and weeds and stuff like that is to go with, is to consider adding some Diamond in with your product, your knock down on those field edges and places where you have high plant bug numbers. So just something to think about. If you’ve got any questions or comments on that, don’t hesitate to give us a call. Last thing I’d say is in some areas we’re also seeing mites starting to break out so you need to keep your eyes open and be looking for mites and aphids. In the south it seems like there’s been some fields treated for aphids already. Your options there are like Transform or Acetameprid which is Strafermax or something like that, something with Acetameprid in it to get control of those aphids. And on the mites, if you start out with Abamectim, which just about everybody does and you don’t get the control that you want to, you need to change your product and start thinking about something like Zeal or Portal or something like that. If you got any questions just give us a call. That’s all I got on cotton .Anybody else got anything you want to talk about on cotton? 

Ben Thrash: I think you pretty well covered it. Rice?

Nick: Yeah we can move into rice. You know there’s been a lot of calls in all crops including pastures on fall army worms and we’re seeing it in rice anywhere from two to three leaf rice and eating the rice back to the soil line all the way up to some of this rice is joint movement or at least green ring and what we’ve seen over the last five or six years, we’ve been doing a lot of manual defoliation because trying to infest caterpillars and getting them to actually take has been a headache, so what we’ve seen for April planted rice until we started seeing twenty, twenty five percent defoliation at green ring we can’t get yield loss. We see a little bit of heading delay as we get into late tiller and into green ring with some defoliation, but as far as yield loss goes, we got to exceed that twenty five percent at green ring. May and June’s different though. Once we get into May and June plantings, we’re going to be at forty percent at late tiller and what we’re calling late tiller is four, five, six tillers out there when the plant basically maxed out tillering and once we get into green ring, we’re going to be at twenty percent. We’ve seen some pretty significant heading delays there, especially in June, upwards, if we get a hundred percent defoliation at green ring so all the way back to the water line, it can be a month later before we get headed. But as far as control options go there and I’m sure we’ll cover this with the other crops as well, we’re going to recommend going out with Lambda and getting back there behind that application within three or four or five days. And if we miss some worms there, that’s happened a little bit for our counter parts around us, is missing some caterpillars with Lambda, coming back with something like, the only other option there is Dimilin with another shot of Lambda included with it. The only other thing to mention on rice there, you know we’ve made this prediction last year, seeing a ton of rice stink bugs all up and down these ditches right now and any grass you turn rows, what it’s going to end up meaning were not sure yet, but be aware, there’s a big population out there. They may or may not end up in the rice. Last year they didn’t but this year’s a totally different year.

Ben: I guess kind of moving over into corn. In corn there’s a lot of fall army worms out there and if it’s pretty late planted, like up towards June, and you’re finding like three army worms per whorl, they can actually cause yield loss. We don’t recommend treating for defoliation early in the season in early planted corn, but when you get into this late planted crop, it’s a completely different situation. And they can actually cause some injury on late planted corn. The same thing goes with soybeans too. That’s actually what I did some of my research in when I was down at Mississippi State. Early planted soybeans, when you plant them in April or early May, they can tolerate a hundred percent defoliation when they’re like in V4 and not see any yield loss associated with that defoliation. However, whenever you get up into June and later planted soybeans, defoliation can really hurt you. We’re really confident with the thirty five percent defoliation threshold in soybeans, but it really needs to be paid attention to when those beans are planted late or when the corn’s planted late. 

Ben: You want to talk about grain sorghum Gus?

Gus: Yeah so on grain sorghum right now I’ve had some calls already on some heading milo that’s got a few midges in it. So I would encourage you, if your grain sorghum is headed and it’s starting to bloom, you need to get out and check for midge and when you think about what your options are on treating it, usually we would spray with a pyretheroid but we don’t want to make aphids, the sugar cane aphids mad at us so we tested the Blackhawk. The last few years we’ve had trials out with Blackhawk and it does a pretty good job on midge and it also provides a little control on the worms too so you might want to keep that in mind, but if you’ve got grain sorghum starting to bloom right now you definitely need to get out and check for midge and I got a report that aphids were starting. I hadn’t verified that yet and we’re going to go make sure that they’re looking at sugar cane aphid and not something like yellow sugar cane aphid or something like that but certainly we want to be aware of the aphid situation and we don’t want to make that any worse if they’re already in the states so I would be concerned about using the pyretheroid but if you’ve got midge out there, you got to get them out. They’re the most devastating pests before sugar cane aphid. They’re by far the most devastating pest in grain sorghum and it’s one you got to watch out for. We’re got a lot of grain sorghum out there this year, so we want to be careful and don’t let them slip up on us there. And this thing that Nick was taking about with fall army worms, we’re actually seeing treatment level in pastures around the state and it’s not just in one spot, it’s all over. It’s in southeast, northeast, up the river valley everywhere, we’re getting calls on army worms in Bermuda grass pastures, so you want to keep your eye out. If you’ve got some pastures, you probably want to check them. Were also getting calls where they’re on the grass in bean fields and the grower goes out and sprays the weeds with Roundup or something and they move right over from the grass onto the soybeans, so you got to keep your eyes out looking for that and be checking that broadleaf signal grass is one of their favorite hosts and that’s where I’d be looking first if I was looking for fall army worms and row crops. That’s a good place to start.

Ben: Our moth traps right now, they’re kind of strange but we’ve got some traps that don’t have any moths in them and then we’ve got some moths traps that are extremely high out there. I mean they’ve got pretty good numbers in them. Our average overall is kind of low but some of those traps are hitting pretty high numbers so in the next couple of weeks is typically when we have our, what we like to call our 4th of July moth flight so we’ll probably have a pretty good feel for them by then. But anyway, be on the lookout for them in some areas. 

Ben: Anything else?

Gus: I think we’re covered just about everything.

Nick: We appreciate it and you’ll give us a call if you need anything. And 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.