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Wireworms with Aaron Esser & Dave Crowder

Contact David Crowder by email at dcrowder@wsu.edu or by phone at 509-335-7965.


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Episode Transcription:

[ Music ]

Drew Lyon: Hello! And 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. We have weekly discussions with researchers from WSU and the USDA ARS to provide you with insights into the latest research on wheat and barley production.

[ Music ]

Drew Lyon: This week we will be discussing wireworms. Our first guest is Aaron Esser, Regional Extension Agronomist from Ritzville. Hi, Aaron!

Aaron Esser: Hey, Drew! How are you doing?

Drew Lyon: Good. And our second guest this week is David Crowder. He’s an Assistant Professor of Entomology here in Pullman. Hi, Dave!

Dave Crowder: Hi, Drew! Thanks for having me.

Drew Lyon: So we’re going to talk a little bit about wireworms here today. And you two have been working on wireworm control since 2008. You have had an assortment of funding sources for this work. There’s a lot of interest in it. Aaron, what do you think one of the largest impacts of this work have been?

Aaron Esser: One of the largest impacts of this work, Drew, I think has to go back to just increasing the overall awareness of wireworms as a pest in cereal grain production, both from the farmer standpoint and the seed treaters. Understanding that they are there, the damage that they’re causing, being able to identify the type of damage, and then being able to assess what they’re doing and then how they’re going to move forward to help minimize the damage from wireworms. I think just overall increased awareness is one of the biggest impacts of our work.

Dave Crowder: Yeah, and one of the other big impacts that we’ve been working a lot on since 2008 is understanding the different species of wireworms that are present in wheat and barley and cereal crop fields. When we started this project, growers were often managing wireworms as just a single pest complex. So regardless of what they had in their field, they were treating it the same way. And we’ve learned a lot over the last eight years that different species. The two dominant species we have here in eastern Washington are called the Western Field Wireworm, which scientific name is Limonius infuscatus, and the Sugar Beet Wireworm, Limonius californicus. And we’ve learned a lot that these species are very different in how they respond to insecticide treatments. They have very different life histories. And so farmers should really be tailoring their management strategies to the species they have. And we’ve been able to give growers in the industry tools to proactively kind of identify what they have in their fields. And Aaron and my work has really identified what types of pesticides and rates work the best for which species you have. So we’re trying to move away from kind of a blanket management strategy to a more targeted strategy where growers are really getting the most effective management depending on what they have in their field.

Aaron Esser: I find I have a lot of growers will ask me or they make comments that I’m using the maximum rate for wireworm control. And I’ll say, well, what’s that? And then they look at me and don’t fully understand all the complexities associated with wireworm control and what you can bring with the Gauchos, Cruisers, and NipsIts of the insecticide world. So it’s been pretty interesting.

Drew Lyon: As we speak about management of wireworms, one of the major management tools has been the neonics, as they’re sometimes called. Will neonics be the way we control them in the future? Or do you see new things coming down the road?

Dave Crowder: Well, a little bit of both I would say. And you know, let Aaron talk a little bit more about this later, but you know, right now the only insecticides that really are registered in wheat and that seem to be effective against wireworms are the neonicotinoids. There certainly are other products out there that are registered in other crops. Organophosphates and pyrethroid insecticides that have also been shown to be effective against wireworms. They’re just not able to be used in wheat cropping systems. And so one of the things that we’ve been looking at is obviously whenever you’re relying on just a single pest control tactic like just neonicotinoids, you’re setting yourself up for it to fail. And then you don’t really have any alternatives. The insects could potentially evolve resistance to the control tactic or any number of things could happen that just relying on that one strategy is not going to be effective in the long term. And so what we do recommend to growers is even though neonicotinoids might be the only real management option right now that they can alternate between the different neonicotinoids, as Aaron said, there’s Cruiser and Gaucho and NipsIt inside are three different types of neonicotinoids growers can use. They differ in their effectiveness. Aaron will talk about this a little more in a second, but we are investigating alternative control strategies including biological controls as well as working with pesticide companies to develop some new products. So I’ll let Aaron talk about that a little bit and then maybe we can also talk about some of the other management strategies that we’ve been recommending to growers that are effective.

Aaron Esser: You know the whole resistance thing is something we’re always concerned about. And we’ve done a lot over the last couple years to look at alternatives to the neonics or finding ways to complement them, a lot of it dealing with crop rotation, understanding that wireworms really prefer wheat over barley. And I think in a lot of instances they prefer lentils and chickpeas over peas. So understanding what a farmer can do with his crop rotation to help minimize it. In some instances, even in that drier or that intermediate rainfall zone, incorporating summer fallow will help reduce wireworm populations. So mixing the crop rotations and some of the things you can do, it’s subtle, but it is beneficial. If you have a higher population in a field, you can potentially seed it later. I’m not saying specifically seed a field three months later because the guy from WSU told you to seed it three months later. But if you have a field that has a high wireworm pressure, don’t seed it first in the spring. Make a point to seed it toward the end of the seeding window, not towards the beginning of the seeding window. There’s a couple of the other things you can do. Seed it a little bit later, increase your seeding rate. Not 170 pounds, but if you’re seeding at 75 pounds, bump it to 85 pounds. If you’re using a half ounce of Gaucho or a half ounce of Cruiser or whatever neonic is your choice, increase the rate to 1.33 ounces or use the label maximum rate for that particular product. I think overall you’re going to be a lot happier and it’s going to help keep these tools that we do have available.

Dave Crowder: And one this I will add to that is in, you know, we have a new grant investigating this. But there is evidence out there in the literature that biological control might be a part of the future of wireworm management. That there are, there’s been a group from Montana State as well as our group has shown that fungi that live naturally in the soil can be effective at killing wireworms as well as nematodes, which are little worms living in the soil kind of kill and attack wireworms as well. And so we have a three-year grant project with a professor at Idaho investigating kind of the viability of these biological controls to either be a replacement to the neonicotinoids or more likely be a complement to the neonicotinoids. So we are working to try to diversify the toolkit that farmers have available to them. In addition to some of the management changes that Aaron mentioned, we think there are also new pesticides coming down the pipeline. Every year we’re working with pesticide companies to evaluate new products. And we don’t typically know a lot of information about what those products are until they’re registered, but there’s definitely a lot of interest in developing new insecticidal controls for wireworms. So I think the neonicotinoids are going to remain part of it going forward, but hopefully we will be able to diversify that toolkit for growers in the near future.

Drew Lyon: Very interesting. I’m wondering if our listeners out there wanted to learn more about wireworm and wireworm control and the work you’ve been doing, is there a place they can go to find that information?

Dave Crowder: Yeah. We have a lot of the information on the SmallGrains.WSU.edu website. We try to keep that up to date with new extension publications or academic publications. We also populate that website with PowerPoint presentations that we’ve given on wireworms or other reports on wireworms. And that site has a lot of information about other pests as well. And we certainly welcome inquiries from growers or other members of the cereal production industry to contact Aaron or me directly. Our emails and phone numbers are on that small grains website. And we encourage people to send us any comments that they have. We, both of us work a lot directly with growers on farms, and so we do really enjoy having that interplay, getting questions from people. It really helps us make sure our research is applicable in the field.

Aaron Esser: Two of them you’re going to find on that website right off the bat, Drew. One of them is on identifying the species. Dr. Crowder talked about the different species and you might be wondering how do I identify those things. Well, we do have a publication extension bulletin on that, that shows some of the key characteristics between the different species. I think it makes it pretty easy for even the, I guess a non-entymologist to identify these species. And then there’s another one on scouting and how do you go about scouting for wireworms. I think those are the two critical ones that are on that website as well as the additional information that Dr. Crowder was talking about.

Drew Lyon: Alright. Well, thank you very much. Aaron Esser, Regional Extension Agronomist from Ritzville. And Dave Crowder, Assistant Professor of Entomology here in Pullman.

Dave Crowder: Great! Thanks, Drew!

Aaron Esser: Thanks, Drew!

Drew Lyon: Thanks for listening to the WSU Wheat Beat podcast. If you have questions for us, that you’d like to hear addressed on future episodes, please email me at drew.lyon@wsu.edu. You can find us online at smallgrains.wsu.edu. You can also find us on social media on Facebook and Twitter @WSUSmallGrains. Subscribe to this show through iTunes or your favorite podcasting app. The WSU Wheat Beat podcast is a production of CAHNRS Communications in the College of Agricultural Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon; we’ll see you next week.

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