Breeding Herbicide-Resistant Wheat with Arron Carter


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Contact Arron Carter via email at or by phone at 509-335-6198.

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Episode Transcription:

[ Music ]

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 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 Dr. Arron Carter. Arron is an associate professor and O.A. Vogel Endowed Chair in wheat breeding and genetics in the Department of Crop and Soil Sciences at Washington State University. His research is directed toward breeding improved winter wheat varieties for cropping systems in Washington State and incorporate diverse rotations in environments. The program goal is to release high yielding disease resistant varieties with good end-use quality that will maintain profitability and reduce the risk to growers. Varieties are developed using a combination of traditional plant breeding methods, molecular marker technology, biotechnology, and high throughput phenotyping. Hello Arron.

Arron Carter: Hello, Drew.

Drew Lyon: So Arron, I was recently at an annual meeting of the Western Society Wheat Science, and there were several papers on this new CoAXium® wheat production system. And that got me thinking that maybe we should talk a little bit about the history of breeding for herbicide resistance in wheat and then talk about the CoAXium® wheat breeding technology. So could you give us a little history of breeding herbicide resistant wheat varieties here in Washington?

Arron Carter: Yes, I’ll do my best. Right. I’ve got a 10-year tenure here. But, you know, I think it all started back in the late 1990s. We kind of had the Clearfield® wheat technology was coming out. So that’s resistance to the Beyond® herbicide. Then there was also RoundUp Ready™ wheat that was being tested, as well. So I’ll just start with just RoundUp Ready™ because that’s a little more simplistic and short. You know, as far as I know, like say the late 1990s, Monsanto released varieties to different breeding programs to begin introgression that round up resistant trait into their varieties across the nation the breeding went on for about five, six years. Different programs had varieties that they were prepared to release but at that time Monsanto decided that it was, you know, better to pull that technology off the market and not commercialize it. And so, although varieties were ready to be released there are no commercially released round up resistant wheat varieties. All of the material was either destroyed or put in storage back at different facilities. So, you know, that was kind of an open and closed story. We started but it never got commercialized. You know, I get that question a lot about round up resistant wheat and is it out there? And, you know, so this can clear everything up. There is no round up ready wheat commercialized and available for production. So then if we switch, like I say, the Clearfield wheat technology was coming along about the same time. So when I was doing my master’s degree at the University of Idaho with Bob Zemetra. That was actually my master’s degree project. So that would have been back in 2002, 2003. It was actually to do the field testing and make sure that the varieties that were developed could withstand the herbicide application and not have a severe injury with that. We started out with one gene resistance, again, back in the early 2000s. We had some varieties that were released. I think the biggest one in the Northwest was ORCF102. We saw a lot of acres of that come into production systems. And then again, just about the time I started here at Washington State University, so 2008, 2009 timeframe, is when the two-gene resistant material started coming along in breeding programs and being commercialized. So kind of in that late 2000, getting into the 2010s and onward, we’ve seen an increase in the two-gene varieties as the one-gene varieties have gone away.

Drew Lyon: Okay. Is there anything special or unique about bringing herbicide resistant traits into wheat or is it just like any other trait that you try to bring into the — into your program.

Arron Carter: Yes, it’s very similar to any other trait. You know, we start with the resistant variety that’s usually given to us by the company. So I can Clearfield® technology. BASF has an approved line that is the donor for the traits. And then after that it’s breeding. If anything, it’s actually a little easier because you spray them. [Drew chuckles] If they die, you don’t want them. And if they live, you keep them, and that’s what you take the field test in. [Drew chuckles] So, you know, it’s a little different because like in disease resistance, you know, there’s these intermediate reactions or you don’t really know if you got the disease or not and it’s a lot of field testing. Herbicide resistance is pretty straightforward because —

Drew Lyon: Even the wheat scientists can do it a little bit.

Arron Carter: Oh, Yes.

Drew Lyon: [Laughter] Okay, so tell us a little bit about your current projects involving herbicide-resistant wheat, both the Clearfield® wheat and whether you’re doing anything with this new CoAXium® wheat.

Arron Carter: Right. Yes, so, I mean, WSU has released some two-gene resistant lines for Clearfield®. So most people would be familiar with Curiosity and Mela. That are Eltan types that have the two-gene resistance to Clearfield®. Those have been out, again, since the early 2010s. And then recently released was Resilience. And that’s targeted more for the high rainfall in a Madsen type background. So we have some varieties that kind of fit all the production zones. And then we just submitted for approval to our variety release committee a two-gen line that will be called Stingray CL plus, and that’s really more targeted for the southern region of the state and then also northern Oregon, and also does well in other production zones but, you know, that’s kind of the focus. So we’ve kind of got a good pipeline going along now for both high and low rainfall varieties of two-gene Clearfield® varieties. So we have seen the acres of those decrease a little bit, just as we got more weeds that are resistant to Beyond®. But we actually will still see a yield advantage because there is so much of that chemical in the soil residual, that you’ll still see a little advantage growing the resistant line, even though you’re not spraying it, just because we’ve used that chemistry a lot. It’s in a lot of our soils.

Drew Lyon: Yes, so as we talk about herbicide-resistant varieties in production systems, such as Clearfield®. I guess that’s one of the concerns weed scientists have had is that it’s really good technology but if you use it too much, you develop herbicide resistance. In the case of Imazamox, we’ve seen a buildup of it, particular in our drier portions of the state where the breakdown isn’t as quick. And so, I think we need to be careful and I think we talk about it. I think you talk about, don’t overuse this technology or we won’t have it for long. And I think because we’re starting to see the breakdown to the Clearfield®, there’s a lot of interest in this new technology. And one of my fears is that we’ll start using it just like we used Clearfield® and it won’t last very long. But it has stimulated a lot of interest. So can you tell us a little bit about where you’re at with that particular herbicide resistant trait?

Arron Carter: Right. So yes this was a technology that was developed by Colorado State University to a group one herbicide. And I believe, Albaugh is the company that will be marketing the herbicide, which is called Aggressor™. And so, yes, we’re looking — and it’s called the CoAXium® wheat system, very similar to like Clearfield® wheat system. So I kind of use those interchangeably. But, yes, we’ve signed the agreement with Colorado State University to begin introgressing the trait into our germ plasma. Now, again, they give us the approved donor, which is a Colorado State hard red winter line. And my job is to convert it into a Pacific Northwest soft white winter line. [both chuckle] You know, so there’s definitely some breeding and selection that we have to do. You know, bringing in the hard red material is a little bit easier because it’s the same market class, converting it to the soft white is a little more difficult. But basically, all the programs, you know, that have signed the agreement basically got the germ plasma about the same time. So we’re all kind of about in the same place, as far as breeding goes. But, yes, the first part is just getting the trait introgressed and resistant lines. Most of that is typically done in the greenhouse and then we shift it out to the field and start doing the field testing to make sure we’re carrying along all the other traits we need for yield potential, disease resistance, end-use quality, and so on. You know, I’ve done the math and I’ve thought as fast as I could go and starting increases with, you know, foundation seed services as fast as I can. Probably the quickest we could get something out would be four to five years in a soft white background that would actually be commercially available, not just because we have the breeding time associated with that. But we also have the seed increase side with crop improvement association. So, again, we’re looking at a few years anyway before we get something out of our breeding program. So right now what’s commercially available are two lines from Colorado State University. I believe Limagrain has licensed one of those. It’s called the LCS fusion. It’s a hard red line, basically, a Colorado State hard red line that is being marketed in the Pacific Northwest. And I know there was a demand for this technology. So a lot of growers did put that variety in, maybe around about 50,000 acres, mainly in the southern part of the state.

Drew Lyon: Okay. And what’s your expectation for how that variety will perform in this part of the country?

Arron Carter: Yes, you know, we’ve looked at Colorado State material before. It’s typically on the earlier side so it’s going to mature very early. So, again, in our environments, I’m not sure that it can capture the full yield potential that we might have to offer just because it matures earlier and is probably going to miss on some of that moisture that’s in the ground that other varieties capture. So probably a lower yield potential. And then also, it’s pretty susceptible to our races of stripe rust. You know, Colorado State doesn’t have that complexity of race structure that we do. So it’s something that the growers need to be aware of. You know, it’s kind of that trade off, like we talk a lot about different traits and what you care about in a variety. So, you know, there’s definitely growers who need that technology. They’ve got weed problems. They’re resistant to Beyond. They need a different chemistry. So this helps with the weed side of it. As far as the variety goes, yes, they’re probably going to be putting some fungicide applications on it and not expecting a high yield. But that’s the trade-off for the weed control.

Drew Lyon: Okay. So they have — they need to realize that this probably is going to yield less and then make that decision whether that price is worth paying to get the weed control they want?

Arron Carter: Yes, I think so. You know, at least until we get the breeding part of it through. Hopefully, we’ll be able to get that yield potential up there.

Drew Lyon: Okay. So you’re talking four or five years. If my math is correct that’s 2023, 2024 for a soft. Will you get a hard red out, maybe a year earlier or about the same time?

Arron Carter: You know, maybe. But it’s probably the same timeline. Again, just because of that germ plasma we start with. We have to, again, bring along the disease resistance that we need, make sure we’re getting protein, and end use quality specifications. So you know, it’s probably about the same time going in both of them. I’m putting a little more of my effort in the soft white, mainly just because that’s our bread and butter. Right. We’ve got a lot more acres of soft white. So I’ve kind of divided my attention more to soft white than hard red. But, again, they’re probably both about on the same track.

Drew Lyon: Okay. Well, I think this is a very interesting technology like the Clearfield. I’m a little concerned if growers overuse it that the ACCH inhibitors we’ve developed resistance to those even more quickly than we have the ALS inhibitors like Imazamox or Beyond. And so, I just hope our growers will use it wisely, don’t over use, maybe rotate it with Clearfield technology and different crop rotations and try to hold on to it as long as possible.

Arron Carter: Right. And that’s something we’ve been trying to, you know, you’ve got the breeding side of it and the development side. But I’ve always tried to stay in close connection with you, with Dr. Burke, you know, with our agronomist team for that same reason. I want to develop the varieties that our growers need but at the same time use them in a system that’s going to be the most sustainable. Because, yes, if we don’t use them in a sustainable way that’s really thought out, and growers are just using them back to back to back in seasons because of the easiness of it. Yes, it’s going to be a technology that potentially doesn’t live as long as it could.

Drew Lyon: Okay.

Arron Carter: And so, extending that with good stewardship is ideal.

Drew Lyon: So when do you suppose growers might see some of these lines and some of the variety testing fields around? When should they start looking for that, I guess?

Arron Carter: Yes, you know, it probably will still be, at least from my program about two years.

Drew Lyon: Two years, yeah, okay.

Arron Carter: Yes. So maybe in 2020, but probably more likely in the, you know, summer of 2021, you’ll probably see a couple of varieties in there. And again, you know, I’m hypothesizing that Oregon State University, Limagrain, some of the other programs are about the same spot we are.

Drew Lyon: Okay. Well, our listeners should be patient, I think. Keep their eyes open for what’s coming out of your program and be careful using this new promising technology. Thanks, Arron.

Arron Carter: Thank you, Drew.

[ 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 ( You can find us online at 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.