Australian Innovation in Weed Control with Caleb Squires & Guy Coleman

Harvester in New South Whales.

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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 guests today are Caleb Squires and Guy Coleman. Caleb is a post-doctoral research associate in wheat biology with the University of Sydney; he is part of the Weeds Research Team based at the I.A. Watson Research Centre in Narrabri, New South Wales. He is originally from Spokane, Washington and came to Australia in March after finishing his Ph.D. degree in Crop Science at WSU. Hello Caleb.

Caleb Squires: Hi Drew.

Drew Lyon: And Guy Coleman is a precision weed control scientist working at the University of Sydney in Narrabri as part of the Weeds Research Team. Originally from Western Australia, he completed a Bachelor of Science at the University of Western Australia in 2014, and his Honors Degree at the University of Sydney in 2016, investigating the use of unmanned aerial vehicles, or UAVs, in plant breeding to expedite phenotyping. Hello Guy.

Guy Coleman: G’day Drew.

Drew Lyon: I would like to ask both of you to tell me a little bit about the research you are involved in here in Narrabri. Let’s start with you Guy.

Guy Coleman: Thanks Drew, so as you mentioned, we’re both part of the Weeds Research Team here in Narrabri, and which is part of a larger project, the Northern Weeds Project, and so my part of this larger project is the engineering control section. So I’m looking at how do we use alternative methods of weed control on a physical manner for weed management. So, we’re looking at how, aside from the chemical side of things, we can incorporate targeted tillage or lasers, or electrical weeding, that on a broadacre basis might be quite impractical or is very impractical, how they can be used on a very site-specific basis. And this includes identification of weeds as one of the major aspects of our research.

Drew Lyon: Okay, so a lot of fun, new technology or what may become new technology in the future.

Guy Coleman: That’s right.

Drew Lyon: And what about you Caleb?

Caleb Squires: So my area that I’m focusing on is weed biology, and so I’m looking at, we have a list of twelve different weeds that are problematic in this area, and I’m studying their characteristics trying to get to know their growth habits, reproduction, dormancy, germination, basically anything that we can identify as a weakness that can be exploited for purposes of weed control.

Drew Lyon: Okay, so I imagine the weeds here are a little bit different than they are back in the Pacific Northwest. What are some other differences you’ve noticed between how things are done here in New South Wales versus the way they were done in the Palouse?

Caleb Squires: Well that’s a great question. First, there are some really fun language differences before we get into the cropping. So for example, pickup trucks are called utes, fields are paddocks, and combines are headers. Australians don’t plant crops, they sew them. Those are just some of the Ag terms, but there’s a lot more. And also, it goes the other way too. If I try to talk about garbs I get a whole bunch of blank stares because nobody knows what I’m talking about. As far as the cropping systems, here they plant spring wheat, but it’s actually grown during the winter so in the Palouse it would be called spring wheat. So they plant in May but it grows during the Australian winter since we’re in the southern hemisphere. And the winter actually isn’t super cold, it gets down to freezing at night but 60’s during the day, that’s in Fahrenheit. And so one of the challenges I guess they have is they’re worried about freezing during anthesis but then after that, that cold mid-winter then it tends to get hot really fast so they’re also worried about heat stress as the wheat matures. The crops grown here are primarily wheat, chickpea, and faba bean during the winter and then there’s a little bit of summer cropping as well, so they get two crops in per year if there’s enough water. And they primarily do the irrigation during the summer, so it would be things like cotton.

Drew Lyon: Okay, and correct me if I’m wrong but it’s considered spring wheat here because it doesn’t need to be vernalized but it does grow over, as you said, over the winter, it’s just that there’s often not enough temperature to really get the plant vernalized, is that the issue?

Caleb Squires: Yes, that’s correct.

Drew Lyon: Okay, so that’s some of the differences between New South Wales and the Palouse, what about differences between New South Wales, the northern crop region here and other parts of the country. What have you noticed coming from Western Australia as being different there versus here?

Guy Coleman: Oh it’s a yeah massive differences around Australia as well so, coming from WA (Western Australia) it’s very much we’re called, “sandgropers” because there’s just sand everywhere in WA and anyone from the descend states, so that includes Queensland, New South Wales, Victoria, that comes through Western Australia are often just is blown away by how sandy the conditions are and if you’re lucky you’ve got a sandy loam and not so lucky you’ve got some sandy, limey sands. So the biggest difference I noticed when I first came here was the black vertisols and the self-mulching vertisols that the remnants of an old volcanic sort of region in the area, and what happens is, these soils when they get wet, they get very, very sticky and so just the practicalities of managing crops in these very sticky soil conditions completely changes the management techniques and is something you need to consider if you’re trying to develop autonomous vehicles or alternative methods of weed control. So if it does get wet and you’re trying to drive this robot through the field, it’s often impossible or can result in severely bogged tractors, cars and small robots. So that’s one major difference, the other one was the temperate climate. So in Western Australia it’s sandy but also very strongly Mediterranean climate and Caleb was touching on the issues of frost there that in wintertime it gets quite cold and so then you get some issues with frost and that summer is very hot whereas and not much rainfall as here in Narrabri, it’s quite, the rainfall is quite consistent it’s starting to drought across the year, and so that can just change the way they can use summer crops as a rotation instead of just purely winter crops. And yeah, that’s just a couple of the big issues there in terms of the soil and climate that I’ve seen so far.

Drew Lyon: Okay, so Western Australia, the WA, would be more similar to the Pacific Northwest because of the Mediterranean type climate so in the PNW most of the moisture comes in the winter, the summers are very dry and warm, same thing there?

Guy Coleman: Yep.

Drew Lyon: Whereas here, on the eastern side of the country, it’s a little more balanced between summer and winter precip?

Guy Coleman: I think so, that’s right. This year’s been very strong drought so winter we got about only a few mils of rainfall but yeah, usually it’s pretty balanced.

Drew Lyon: Okay, well one of the things that brought me here to Narrabri is the problems Australians seem to have with herbicide resistance and seems to be a lot of that around here. Caleb, can you talk a little bit about why that’s such a problem in Australia.

Caleb Squires: Yes, sure, the interesting thing about that I think is that there’s a lot of history that goes into explaining that. So prior to the 1980’s I believe, there was a lot of sheep production and so they planted a lot of annual ryegrass for fodder for the sheep, and then when sheep prices crashed then they tried to take all that pasture out and grow wheat crops instead and so since ryegrass is you know, an outcrossing species with lots of diversity it just set them up for problems. And another thing that I noticed when I got here, just as I was driving around and seeing sprayers out in action, I couldn’t believe how fast they were driving. So typically here, a traditional spray job is done at 13 miles an hour and they have a carrier volume of about 5 gallons per acre, which is you know, not what we recommend in the U.S.

Drew Lyon: Not for good coverage, is it?

Caleb Squires: And I think that also in you know, definitely causes problems. You get sub-optimal dosage on the weeds.

Drew Lyon: So the annual ryegrass or I believe some people call it rigid ryegrass, is very closely related to Italian ryegrass, which is a major problem in the Pacific Northwest and that’s really one of the things that attracted me to come here is to see what I could learn to help deal with that weed. Guy, do you have any insights on herbicide resistance and some of the things that are being done here perhaps that we might learn about and carry back to the US with us?

Guy Coleman: Yeah I think in Western Australia particularly there’s been a strong focus on harvest weed seed control so Michael was, Michael Walsh, our supervisor, has been very a big proponent of harvest weed seed control and having spent much of his time in Western Australia, I think it’s driven a large sort of shift towards that practice and then not having a large amount of experience in the US, I’m not sure what happens over your way but by the sounds of it, harvest weed seed control is a big type of control method used and so the Harrington Seed Destructor is really an opportunities to manage weeds around harvests, although it has issues in terms of requiring the weeds themselves to maintain seeds right until harvest period, so that’s probably one thing that could be exported a bit from Australia. But we are very good at developing herbicide-resistant weeds and so hopefully we don’t export any of those.

Drew Lyon: Yeah, maybe we can learn how to do it from you because you’re going to have to figure it out because of all your issues with herbicide-resistant weeds here. Okay, one of the things you’ve mentioned earlier Guy, was the use of robots. You’ve mentioned robots getting stuck in the sticky mud. What do you see as the role of robots and weed control in the future?

Guy Squires: Yeah, I think that’s an interesting one because some people might see them as potential challenge directly to herbicides but I think the way we’re working with them here in Narrabri is they can complement the role of herbicides in a cropping situation so I’ve sort of termed them the group T, or group technology, because they just offer where herbicides fail in like seasoned weeds where they’re quite large and often ineffective. Technology really has strengths because the weeds are larger, they’ve got more time to control them, and often the robot can go around and target these larger weeds much more easily than say the younger, smaller weeds. And so that means you have more time and you have large leeway’s in terms of your persuasion and accuracy, and it means that these technology or group T options are much better suited for these larger weeds in poor ecosystems and so I think if we use the chemistry to control those earlier weeds, and use the forte of chemical control when it sort of early post-emergent weeds, then complement that with light post-emergent robotic usage, I think that could be a really good fit there.

Drew Lyon: Okay, I can see where maybe chemistry tillage early and then chemistry maybe and then maybe robotics and then harvest weed seed control, you can put together a full package because they all kind of have their strengths and weaknesses and what we tend to do is just throw one thing at them until it doesn’t work anymore, and if we can throw multiple things at them, maybe we can maintain our ability to control these weeds much longer than we can when we just use one technique.

Guy Coleman: I think that’s right. It’s all about integrated weed management so you use some cultural control methods, which we’re also looking at with the Weeds Research Team here, with the sod in competition, and then all your crop rotations as well, and then combine that with the chemistry, the tillage, and the… as well as the robotics and the harvest weed seed control, you should hopefully have a pretty good handle on it.

Drew Lyon: You can’t give these weeds any quarter or they’ll take advantage of it. Caleb, what Australian technologies do you think are easily transferable to Eastern Washington?

Caleb Squires: So Guy talked a little bit about harvest weed seed control, I think that there’s definitely some potential there, there’s one thing we’d have to figure out on the Palouse to get that to work; so in Australia probably 90% of the farms use controlled traffic, which means that they have their planters, and their combines, and their sprayers all set up on the same wheelbase to cover you know, the same effective width, and so that allows them to do things and harvest weed seed control where they can direct the chaff maybe into the tram lines or something. And so obviously there’s some challenges with that in the US, in the Palouse, because you know the rolling typography, if they could figure out how to do that then I think that would open up some additional options as far as harvest weed seed control.

Drew Lyon: Alright, well I appreciate getting the perspectives from both an Eastern Washington person who’s spent some time here Caleb, and Guy your perspective moving into the area of robotics and some of the harvest weed control, weed seed control issues here. Thanks for your time.

Guy Coleman: Yeah, thanks, Drew.

Caleb Squires: Thanks, 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.