A New Solution for Wireworm Control with Aaron Esser

March 22, 2021

Show Notes & Resources Mentioned:

Contact Information:

Contact Aaron Esser via email at aarons@wsu.edu.

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Episode Transcription:

Drew Lyon: Hello. Welcome to the WSU Wheat Beat podcast. I’m your host, Drew Lyon, and I want to thank you for joining me as we explore the world of small grains production and research at Washington State University. In each episode, I speak with researchers from WSU and the USDA-ARS to provide you with insights into the latest research on wheat and barley production. If you enjoy the WSU Wheat Beat podcast do us a favor and subscribe on iTunes or your favorite podcasting app and leave us a review while you’re there so others can find the show too.

[ Music ]

Drew Lyon: My guest today is Aaron Esser. Aaron has been with WSU Lincoln/Adams area Extension for 23 years, mostly concentrated on dryland cropping systems and conservation tillage. His research and extension program has focused on wireworm management and cropping systems since 2008. His work with wireworms has covered the biology and distribution of this pest as well as cultural and chemical control of this pest. Hello, Aaron.

Aaron Esser: Hey. Hello, Drew. How are you?

Drew Lyon: Doing well.

Aaron Esser: Good.

Drew Lyon: So you’ve spent a large portion of your program over the last decade or so focused on wireworms, which is the larval stage of the click beetle. Can you tell us a little bit about how you got started on this project?

Aaron Esser: Yeah. First of all, I want to reiterate and I think I’ve — everyone who’s ever heard me talk regarding wireworms is that I’m not an entomologist and my passion for entomology is pretty limited. But a group of growers came to me early in 2008, maybe late 2007, and asked me if I could work on an issue. Because Lindane was removed from the marketplace starting in 2006. And they wanted to know if I could work with a pest that seemed to be giving them some issues, and it was wireworms. So we sat down with a couple of growers and it all went from there.

Drew Lyon: Okay. And Lindane was a chemical they had been using up to that point for successful wireworm control?

Aaron Esser: Yeah. It was one that was successful for close to like 30 years. So it had a good run. It went away. Had some issues. And that left a product called neonics on the marketplace for growers to use. And, you know, Lindane had some residuals in the soil and stuff. And with those residuals, neonics seemed to be producing pretty good results. But once you start seeing some of the Lindane get out of the soil and stuff, the neonics really started to fall down a little bit. Two studies I did early on that growers wanted me to look at was a study looking at Gaucho at two ounces versus the check. And, you know, two ounces at that time was like, wow, that’s way above anything any farmer had ever tried with this Neonics. And I remember when I was given the first field with it, we were up on hill overlooking the trial and stuff. And I said, yeah, we’re using two ounces of neonics, and one of the farmers made one of his cracks. He goes, you can’t afford two ounces of Neonic. And I looked at him and then I looked at the trial and I looked back at him and I said, I’m not sure you can afford not to, just looking at the results. And that was kind of the start of it, along with the trial I did where we put on zero, a quarter ounce, half-ounce, and one ounce of Cruiser. And at that time, that quarter ounce of Cruiser was the heavy wireworm rate. And, you know, we had put that trial in and we were seeing significant damage with one ounce of Cruiser, which was probably one of the early breakthroughs that we had. Because at that time, a lot of farmers were getting upset because they were putting on the heavy wireworm rate of .25 ounces of Cruiser and they were still having significant wireworm damage. So there was a lot of finger-pointing in the industry saying, I paid for it, you didn’t put it on. And there were actually growers who switched seed dealers because of it. So that was one of the big breakthroughs with that trial. And early on, Keith Pike, was really instrumental in helping me get started with the program. He was an entomologist with WSU, has since retired. But he was really instrumental, along with Lincoln Adams Wheat Growers Association, and Crop Improvement. They helped do a lot of the early funding. And the education early on was mostly focused on identifying the pest, identifying the damage of the pest, and figuring out ways for farmers to scout this pest.

Drew Lyon: Okay. You mentioned one of the things you consider to be a breakthrough with the work you did. Are there any other key breakthroughs you’ve had?

Aaron Esser: Well, that early work and the trial where we had the zero, the quarter-ounce, half-ounce, and one-ounce really led to one of the major breakthroughs. Because we had that at two locations, Drew. And it was really interesting because they said neonics don’t reduce wireworm populations. And at one location up in the Wilbur area, we actually had a significant decrease in our wireworm population where we did increasing rates of neonics. At the location that we had just south of Davenport, we actually had no significant difference in our wireworm population. Not a bit of difference amongst all those treatments. And as a scientist, you know, I’m sitting here going, how can I explain this as bad research? What’s going on? You know, just starting to question every move I made. And then we sent some wireworms off to Montana State, who did a DNA analysis on them. And lo and behold, at the location at Wilbur, we had a species of Californicus infuscatus, where we had infuscatus up there. And at Davenport, we had Californicus, Limonius californicus. So instantly it was one of those aha moments, we’re dealing with two different species. And then that led into some work. We brought in David Crowder came onto the program to kind of replace Keith Pike when he was retiring. We brought in our graduate student, Ivan, Ivan M. And then the Grain Commission got involved and put a lot of additional funding behind it and we got some USDA-NIFA funding. And then we started going after looking at the detail of this pest. And Ivan did some great work focused on the distribution of wireworms across the area. You know, overall, there were 17 different species. But three of them really stuck out as dominant pests that we have in eastern Washington and northern Idaho and part of Oregon as well. And so these three pests — and then we started looking and taking a closer look at them. And they have completely different feeding habits and everything, and that really helps explain some of the damage, why we saw damage in one area and not at the other. So that was one of the biggest breakthroughs I think we had moving forward. We also did a lot of work on cultural controls. You know, we found that wheat was a lot more susceptible than barley to wireworms. So if you had heavier infestations, it may be more advantageous for a farmer to put in some barley instead of spring wheat. We also started looking at summer follow and incorporating that. A lot farmers in this area were using continuous cropping systems. So then by incorporating summer fallows and other means, we could reduce wireworm populations in the soil. And then growers started incorporating peas into their rotation, both winter peas and then chickpeas. And one of the primary reasons growers up in the Lincoln County area and some of this intermediate rainfall, started looking at peas was to utilize a product called Capture LFR. That’s an in-row applied insecticide. And that was to reduce wireworm populations. And we also found that that reduced wireworm populations by about 50%. It didn’t eliminate wireworm populations, but we could reduce wireworm populations, maybe get them to a more manageable population. So those are some of what I thought was some of the biggest breakthroughs. You know, our education at this point, it’s really focused on, how do we incorporate these integrated approaches to help control — not necessarily control but manage — wireworms to where to minimize their impact on our overall cropping systems. And it really took a lot of planning and efforts moving forward to put these things in place. During this whole time, also, we were looking at lots and lots of seed-applied insecticide studies. Over I think since 2009 or ’10, I’ve worked with nine different companies, putting out hundreds of treatments. Just in 2020, we looked at 29 different treatments for wireworm control as a seed-applied insecticide. So we were also doing that on the side along with all these other larger-scale stuff and the distribution and developing these cultural controls.

Drew Lyon: You mentioned earlier three dominant wireworm species. Do you find you have to manage those species differently, are they the same management approaches work for all of them?

Aaron Esser: No. It was interesting, you know, infuscatus happened to be — Limonius infuscatus happened to be the most prevalent in the Pacific Northwest, but it also did the least amount of damage compared to californicus. How it’s related to growers is, one californicus will do as much damage as two infuscatus.

Drew Lyon: Okay. So if you’ve got californicus, you need to be more vigilant?

Aaron Esser: You need to be a lot more aggressive.

Drew Lyon: Okay.

Aaron Esser: And Cruiser had no impact. You could utilize two ounces of Gaucho and you could reduce both of those species of wireworms. And then when you got into the dry, dry area, you get into a different species, and it’s Selatosmus pruininus. And it too requires a little bit different to manage. The two ounces of Gaucho would reduce wireworm populations but it would only reduce the neonates, the youngest of the wireworm populations. And really had no impact on the larger, more mature wireworms. That’s one of the things that makes wireworms — I forgot to mention maybe early on, makes wireworms so difficult is these things can remain a pest anywhere from two to five years in the soil, upwards of 10 years. And that’s that Selatosmus pruininus, the dryland species, it’s in the soil for up to 10 years. So unlike most insects, you know, where they go through a quick lifecycle, you know, the larval stage is a very long lifecycle for an insect.

Drew Lyon: Yeah, that is quite long. Interesting.

Aaron Esser: They just don’t want to mature. [ both laugh ]

Drew Lyon: Sounds like kids these days!

Aaron Esser: We all know a couple like that, don’t we, Drew?

Drew Lyon: Yeah, exactly. So Dale Whaley recently posted a timely topic on a new product called Teraxxa insecticide.

Aaron Esser: Teraxxa.

Drew Lyon: What can you tell us about this development and what does it mean moving forward?

Aaron Esser: You know, I talked about I looked at a lot of different products with different companies over many years. One of the companies I hadn’t worked with until 2017 was BSF. And in the spring of 2017, they contacted me about doing more of a long-term study, a multi-year study, looking at one of their products for wireworm control. And you know, this was really my first time working with them, and so I was kind of leery, you know. I was pretty skeptical at first, especially when they wanted to do a multi-year study. And their grand scheme that they were laying out and everything, I’m like, I’ve looked at too much wireworms. And, you know, am I wasting my time? Am I wasting their time? Am I wasting the grower’s time? And the ground I was putting it on? But we established a study in 2017 and it was with a product broflanilide. And, you know, it looked really good the first year. But the thing that really set it apart, you know, the yield our check, average 28 bushel, where we had no wireworm control, just a fungicide, the heavy rate of Cruiser at 1.33 ounces — the highest legal rate, labeled rate — went 62 bushel. But the Teraxxa will average 70 bushel an acre. And that was really cool to see. But the thing that was really nice is coming back to subsequent year and putting wireworm traps in the ground and removing those traps. The check overall, Drew, we averaged almost 14 wireworms per trap. With the Cruiser 1.33, we also averaged 13 wireworms per trap. You know, no significant difference there. But with the Teraxxa, over those two years of doing this study, putting two traps per plot across this area, we only found a total of two wireworms, and both of them were small neonates. And so that was really exciting, you know, to see. It’s been a long time. Never really pulled bait traps out of the ground that were just empty. And so that was, you know, one of my big aha moments. And, you know, I’ve mentioned in stuff it was a game-changer. And I think for the industry moving forward, I think it really will be a game-changer.

Drew Lyon: That is exciting news, because that’s been a pest that’s really bothered our growers for, like you said, since Lindane went away.

Aaron Esser: Yes. And it can sneak up on you at any time. Growers didn’t have problems with it and all of a sudden, boom, they have problems. You know, most growers will misdiagnose wireworm damage for a couple of years. As those populations mature and increase, you know, you go from — I was a little disappointed in that field, the stand wasn’t quite there, the weeds. All the growers early on always focused on the weeds. You know, one farmer down by Uniontown, on his winter wheat, always had severe downy brome. Couldn’t figure out why. And once he figured out wireworm control, he really did a much better job with his downy brome. Rob DeWalt early on, he was always having troubles with wild oats. You know, submitting the drop on there, couldn’t get rid of the wild oats. Well, if you don’t have much crop there, the wild oats take over. And one thing we found in our research is wireworms don’t like oats, including wild oats. [ Drew laughs] And then Mark Shuffles, one of the other coppers, we had the long-term study with. He was having a problem with trying to control Russian thistles, you know. So anytime you start decreasing your crop, that crop competition, you know, there’s always something there to fill that void. And in this case it was wheats. And so it’s really nice to see something that, you know, these things are clean. And you know, even coming back, Drew, that second year, where we ran Cruiser the first year and then we’d come back with a check the second year. We harvested seven bushel where we had Cruiser the first year, came back with no insecticide the second year. Over two years, we averaged seven bushel. Where we did that with Teraxxa, we averaged 68 bushel, almost 69 bushel.

Drew Lyon: You don’t even need statistics to tell you that!

Aaron Esser: Almost no difference than using Teraxxa two years in a row. Yeah, you don’t need stats, you don’t need a statistician for those numbers. You know, and it’s interesting, I was just listening to the Wheat Growers Pod– or one of their seminars the other day on seed care. And Syngenta is bringing a product to the marketplace. Unfortunately, it probably won’t be here till 2024. Pinozilin, I think. And I’ve looked at that a little bit too, and it’s going to have some of these same characteristics I think where it can, you know, reduce wireworm populations in the soil. So it’s nice to see these products finally getting to market. We talked about it, Teraxxa did get registered on January 15th. And a lot of the effort on that went to the Grain Commission. They pushed in for a Section 18 for it, even though they were trying to get registration. It kind of stalled, something about all this COVID stuff and things were kind of stalling and not quite moving like they wanted to. But by simply putting in a Section 18 and forcing the issue, it really helped get the labeling in place so we could have this product available to us for the 2021 crop year.

Drew Lyon: Well, IIt sounds like exciting news for the wheat industry. Where can people go to find more information on wireworms and how to manage them?

Aaron Esser: Well, I’ve never been shy, so my email address is always there: aarons@wsu.edu. It’s pretty easy to find on any Google search or anything. And then most of our stuff, like Dale Whaley’s summary, his timely topic is on the Small Grains website. All our stuff on how to trap wireworms and stuff, all that’s on the Small Grain website. One of my latest presentations is going to be available here, should be available on the small grains website as well. So there’s a lot of great resources there. And if you don’t find what you’re looking for there, give me a call and we’ll figure out where we need to go.

Drew Lyon: All right. Well, Aaron, you had some good news here for our listeners today. Thanks for sharing that with us.

Aaron Esser: It’s nice to finally bring good news! You know, we were waiting for 2020 to get over with, and some people were questioning, well, 2021 is rolling in. But, wow, I like 2021, Drew. This is great for me and for farmers across eastern Washington and in Oregon. The Oregon Department of Agriculture approved it for Oregon as well just the other day.

Drew Lyon: All right, a good way to start off the year.

Aaron Esser: Yes.

Drew Lyon: Thanks a lot, Aaron.

Aaron Esser: Thank you, Drew, appreciate it.

[ Music ]

Drew Lyon: Thanks for joining us and listening to the WSU Wheat Beat podcast. If you like what you hear don’t forget to subscribe and leave a review on iTunes or your favorite podcasting app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon — that’s lyon@wsu.edu –(drew.lyon@wsu.edu). You can find us online at smallgrains.wsu.edu and on Facebook and Twitter @WSUSmallGrains. The WSU Wheat Beat podcast is a production of CAHNRS Communications and the College of Agricultural, Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon, we’ll see you next time.