Welcome back to the War Against Weeds podcast. This is Alyssa Essman, Weed Science extension specialist for Ohio State and today, my co host is Joe Ikley, North Dakota State University. How's it going today Joe?
Going pretty well. We're back above zero fahrenheit for one of the few times this February as we're recording. So no real complaints.
Awesome. Well, today we're joined by a co host, actually across the world, so probably a lot different weather conditions where he's at. So So today we have Michael Walsh. Do you want to tell us a little bit about where you're at and what you do Michael?
Yeah, sure. Hi. Alyssa, hi. Joe, yeah. So it's a balmy 25 degrees Celsius here in Wagga in New South Wales. So I'm on the campus of Charles Sturt University where I'm a professor of plant science and horticulture, focusing on weed control in cropping systems, grain production systems in particular,
awesome. Well, thank you for joining us. We've brought Michael on today to talk about kind of a fun, interesting topic. I know, one of the questions Joe and I get are, sometimes, how can we use, you know, mechanical weed control, along with our comprehensive herbicide programs. And so we're talking today all about targeted tillage. And so this is an area where Michael has some experience and can kind of shed some light on some of the research and activities around
this targeted tillage. So before we get into some of that, Michael, could you describe to us a little bit what is meant by this term, targeted tillage.
Yeah, sure. So targeted tillage is really about, I guess we call it site specific weed control, but with a spot tillage practice, if you like. So you're concentrating a tillage action around the weed target for a site specific weed control output or outcome.
So in reading about some of this work, you talk a little bit about the origins, and I think that's kind of a fun story. So could you tell us a little bit of the background of this approach and how you started studying targeted tillage? Yeah,
it is a fun story. It's a story that came out of, well, harvest weed seed control, actually. So harvest weed seed control is a non chemical weed control tactic that we've been working on for many years, and through the peer to peer learning process that we developed in trying to get farmers on board with harvest weed seed control, used to take growers around to visit other grower groups and talk about, you know, their experiences with this weed novel weed control
practice. So one one day, we were visiting a farm, and the one of the leading proponents of harvest weed seed control was walking ahead of us, talking to the owner of the farm, and they're walking across a fallow so in that part in where they were, which was in southern Queensland, the fallow phase occurs over summer, where it's all about maintaining a completely weed free area to store moisture for the
subsequent winter crop. And as they were walking along, the the owner, the farmer, was walking from weed to weed and just kicking these weeds out with his with his boots. And the farmer who was walking with him was noticing this, and when we rejoined the group, he came over, and he's all excited. He said, Did you see that? Did you see that this guy was just kicking out the weeds with his boots? How easy would that be to come up with some sort of mechanical tool that just kick
the weeds out? And that's how the whole idea of targeted tillage came about. We're looking at just essentially kicking out weeds in a low weed density situation, to just stop these weeds from using moisture and nutrients and having
detrimental effects on subsequent crop crop. So Subsequently, we got a project funded by the Grains Research and Development Corporation, and we worked with some mechanical engineers at the University of Western Australia, and we came up with what the farmer referred to as a weed kicking device for what we call now as targeted tillage, and we've actually
named it the weed chipper, right? So the weed chipper has been developed as a targeted tillage implement, and the aim for the use of that implement is to target low density weed populations. You know, in a fallow phase, it's quite aggressive, but very effective on large weeds. And essentially, what the scenario that you're looking at is that you've got weeds surviving the first herbicide treatment of the
fallow. They're typically at low densities. And so you come. Back in with this weed chipper, and you take out the survivors, and the effect is not only weed control, but you're probably also going to be removing herbicide resistant weeds that are left surviving after initial herbicide treatment.
That was going to be my follow up question, has this so far been implemented mainly after an initial or maybe even a second herbicide pass, so higher likelihood of herbicide resistant weeds being targeted, so you've kind of gotten rid of the rest of the weeds and taking out the survivors with this system.
Yeah, that's right, Joe. So the because it is a tillage implement, the aim is to, well, the use is for low weed densities. And so we typically refer to a weed density of, say, one plant per 10 square meters. Anything much higher than that results in too much soil disturbance and doesn't then fit with our conservation agriculture programs. So yeah, we are definitely looking at low weed
densities. Now that may be an initial emergence is quite low, but most commonly, it's after you had one or two broad spectrum herbicides applied across the whole field. You're taking out survivors, and potentially any sort of late emerges as well. So the timing of use in terms of achieving effective weed control can be, it can be anytime, real, really, because it's a tillage based weed control, it's not really limited by the weather, other than if it's actually raining or
straight after rain. So there's not the same limitations with this weed control activity, as it is with herbicides. So you potentially when you're able to use it, you can use it 24/7, around the clock, but yeah, the limitations are if the soil is wet. So tillage based weed control works best when you've got a drying soil environment. So you obviously rain and immediately after rainfall is not an ideal condition.
And so maybe to back a little bit up here, just thinking through this whole system, because it might be foreign to many of our listeners. And I know Sarah is not joining us today, but she'll probably have some no till fallow folks that they're listening in. And this really would be targeting the annual weeds within the system, because we're not really going to probably remove many perennials or or have you tried that? Maybe?
Um, yeah, we can. We can remove perennials so we it's effective on return cotton. So that can be cotton plants that have survived over into the next season and are quite large and difficult to control because it is a very aggressive tool. It's quite a high impact when the implement engages with the soil, and probably should have described that action a little bit more closely. Yeah. So getting back to your question, Joe, it's typically in our production systems, in our
annual production systems, we have annual weeds. We don't tend to have a lot of perennial weeds persisting from one year to the next. So yeah, they are the primary target. But yeah, as I said, they can. This system can potentially be used for on quite large perennial weeds if needed. Yeah,
we're it's always going to vary based on where, what state you're in, for those listening from the States, but I mean, I look at this as some of our perennial weeds. We have foxtail barley, it's a Hordeum species that is pretty shallow rooted that will probably be a good fit. But we also have some Canada thistle and some deep rooted perennials that may be a little bit different.
Yeah, sure that should have no problems with those. I probably feel as though I should have described the time action before this point too.
I was going to ask that. And then also, I know there's videos. So Michael, if you know of name of a search term for the video. We can always link it to show notes too, because it's a pretty interesting thing to watch. So probably worth describing that action, and we'll also link the videos to it, yeah. So
the the action of the target tillage implement is based around what we refer to as the response time. So it's a typical cultivator time with a hydraulic breakout. So instead of a spring breakout system, it has a hydraulic cylinder that acts as the breakout if the tine has hits a rock or something like that. That's in its normal operation. When set up as as targeted tillage, the system is adjusted with additional springs
that actually hold the time out of the soil. So the time travels at about 10 centimeters above the soil surface, or maybe a little bit higher, held in that position by these these springs. The hydraulic tine is still, the hydraulic ram is pressurized. And when a weed is detected, that RAM is triggered to push that time quite rapidly into the soil. So from standby to soil engagement and then back to sand standby, all happens within
point three of a second. So it is very fast, very rapid, and has essentially been developed to achieve, if needed, a weed control action every meter traveling at 12 kilometers per hour. So it could actually be a very rapid tillage operation if needed,
could you describe to us then how this system knows when the weeds are there. Like, how are we detecting it to trigger this, this rapid response time system? Yeah, so
the detection system that we've got on the weed chipper at the moment is essentially just a reflectance based detector, so something like a weeded or a weed seeker system, because the weed chipper has been developed and is being used in fallow weed control. So anything that's green, anything growing in those situations, is considered a weed. So a fairly simple sensor based detection system is used. We are looking at reconfiguring the time arrangement so we can
potentially use it for row crops. So we might want to use it in sorghum or cotton or even corn, I suppose, in the US, in the early stages of growing season. And in that scenario, you would have potentially use more sophisticated detection systems, so maybe a camera based weed recognition system that would trigger the tines when a weed is detected.
That was my follow up was, if you've gone that pathway and sounds like you are, because that's the first follow up question I know I'll get, is, can we use this inter row within crops, and sounds like, stay tuned.
Yeah, you can't. Well, yeah, that's right, stay tuned. But also stay tuned because there is a, not a new, novel system that's being developed, which is what we call as an active tool system. And that system is a electric motor driven paddle, if you like that, when traveling through the when traveling across the field, when a weed is detected, the paddle dips into the soil where the weed is and essentially just
scoops the weed out. And so that system has been specifically designed for in crop use, specifically for row crops, at this stage, 20 to 30 centimeter wide paddles on these tines, you could potentially have two or three tines per row, depending on on the row width. It's a low energy system and quite finessed in the level of soil disturbance that occurs but still achieves effective weed control, and the efficacy actually increases with
speed. So we're finding that as we go from nine kilometers to now up to 18 kilometers now that the efficacy improves, because you get more of an actual impact as that paddle dips into the soil.
So so the faster speed is that meaning we're the paddle will be in the ground for a little bit longer time. So is it a paddle response of dropping and then raising back up, or is it the speed of the paddle hitting the ground? I don't know if that question makes enough sense there.
Yeah. No, that makes perfect sense. Joe, so it is actually the speed of the paddle hitting the ground. So if you can imagine, well, it's a bit like if you you hit something just moving your arm slowly, compared to if you hit something moving your arm quickly. There's a quite a can be a potentially big difference in force, especially if you've got big, strong, powerful arms, like you. Joan, so that's that's
essentially the same principle for the weed. So with the paddle hitting at higher speeds, is a lot more impact force, and so a lot more sheer pressure on that, on that weed, on the weed roots, to excavate them out of the soil.
Next up, I was just thinking traveling faster for weed control is music to the ears of many American weed control folks,
and the same here in Australia too, which is, I guess, part of the motivating force for looking at the efficacy increase with speed is that large production areas that take time to travel over to for effective weed control. And so you gotta be able to kill weeds quickly and effectively.
So you mean, you mentioned a couple things there that I think are exciting, one of which is this reduced kind of impact on the soil system in Ohio, a lot of no till acres. Right? And so this kind of reduced tillage in a very targeted manner, in a way that's different than our herbicides, I think, is exciting in this site specific management. But one of the other things is the efficacy. So could you talk a little bit about the efficacy of targeted tillage, like, what?
What's your kill rate? Are certain species more or less impacted, yeah.
So the, if we talk about the the weed chipper, so it has a the blade on the weed chipper, which I should have described earlier. It's a flat blade with a little point in the middle. So instead of like a conventional cultivator sweep, the blade is actually flat or across the width, so 30 centimeters or 40 centimeters wide, but it's just like a flat hoe engaging with the soil at speed, so it does potentially
cause quite a bit of soil disturbance. So it will be a 30 centimeter wide divot by maybe 40 centimeters long, depending on the depth of engagements and how long you decide to engage the soil for, and you can adjust it. You can adjust it for larger weeds or reduce it for smaller weeds. But that reduction is limited because it is such a big, aggressive implement, but it is, it is suited for that fallow situation where typically you do get larger weeds, and you do need that, that extra level
of soil disturbance to achieve control. And we have actually got 100% control whenever we've got the tool engaging at the right time. And the weed has been, you know, sensed appropriately and the system set up properly. The times when we don't get 100% control, it's because maybe the weed is right on the edge of the blade and it gets a glancing blow, and even though the weed might be affected a little bit, it still
survives. So yeah, that's sort of the typical scenarios where you do get some sort of survival for the the novel targeted tillage system that we're developing now, the the active tool design system, which has the little active paddle, so that's a 20 centimeter wide paddle or tool, and it is developed for row cropping systems, and probably targeting smaller weeds, particularly if you have to go at slow speeds, then it will be highly effective on small weeds, but maybe not so
effective on larger weeds at higher speeds, though, with that increased impact force, there will be particularly, probably similar efficacy as the as a weed chipper, to a point, I suppose it all, it all depends on the weed size. But I would suggest that if you're trying to get larger weeds, and you need a bigger tool to have a greater chance of success, whereas the the the active tool system would be more reliable on medium sized weeds. And so what I'm referring to, in terms of larger weeds,
are things that are about a meter in diameter. So they're quite big, big plants with a maybe a two centimeter tap root on them, something like that, which two centimeters is probably nearly an inch in diameter, will be less Yeah. So the weed chipper can handle those without too many issues, but the active tool system might struggle, but hopefully you're not having those occurring in your crop.
We hope not either, but those questions always come up for us, but so something you said there triggered a follow up question for me. So for the weed chipper, in that more fallow targeted system, you mentioned, some of these scapes might be on
the edge of the blade or something. So I'm I started thinking, for many of the folks in the US, we think about the different site specific sprayers, and there's the question of, Do you have a section turn on with nozzles meant to overlap, or even nozzle banding, and pros and cons of
that. And so I was just thinking with the weed chipper itself, the setup, are these blades set to overlap at all, or they kind of 30 centimeters of width bump it up right against another 30 centimeter with blade, so that you could have some of these potential skips right on the edge of where those two blades meet.
Yeah. So you would, yeah. Ideally you would set them up so that there was overlap. But it comes down to cost, of course, and so the the arrangements will be the time arrangement will be up to the growers, what they what they can afford to do. But ideally, you'd expect that you'd allow some overlap to make sure that there are no escapes because of near misses on the edges. Yep,
makes sense to me. Sorry, Alissa, I'm full of side questions.
No, no, you're good. I think, I think that kind of leads here into another question we have. Kind of related to the sea and spray, I know right now it's based on reflectance and difference between green and not green and when it's triggered. But if there is the potential to have this in crop, I think one of the questions will be, how does it compare to other in crop, site specific management tools like
the CN spray. So I guess do you have any thoughts on that, or how they might be used together or in tandem, or what that might look like?
Yeah, that's a good question. I guess we would see these targeted tillage implements used for site specific weed control in conjunction with herbicides. So, you know, they're meant to be an alternative to take the selection pressure off herbicide so you can actually come in and clean up survivors that have persisted through herbicide treatments for whatever reason, whether it was a, you know,
ineffective application or due to herbicide resistance. So that's, that's where we see the the true role of these systems in terms of efficacy. They should be similarly effective. The, you know, steel is a pretty blunt implement when it comes to using it for for weed control at high speed. There's a lot less environmental restrictions on on targeted tillage as compared to herbicide treatments, but there are other restrictions. Of course, there may be probably slower operating speeds, maybe,
but you know, there's pros and cons for each system. There's no such thing as the perfect weed control tool,
so you kind of touched on it there. But what role do you see targeted tillage and these sorts of alternative or supplemental weed management strategies kind of playing in the future of weed control programs?
Yeah, well, I love to see them have a big role, actually. So even though I work quite a lot in alternate weed control technologies, I've previously worked a lot with herbicides, and herbicides are still by far the best weed control tool that we've got, and probably likely will stay that
way. So we need to keep using them. We need to keep using them by preserving their use and using them when we really need to use them, and using them effectively when we really need to use them, but we have to support their use with other control techniques. We have to use other things to take the pressure off herbicides, and that's where targeted tillage
comes in. It we know a lot about tillage as a weed control tool, other more novel techniques we don't know so much so, you know, there's talk about lasers and electrical weeding, and, yeah,
we're learning about those. But tillage has been around for centuries, and so in recent times, we may have forgotten a little bit about how you use tillage effectively for weed control, but that knowledge is still there in the background, and we it can be brought back to life and used effectively in in a more unique way than what it has been used previously and still fit with their conservation production systems that are very much focused on reducing the level of tillage in
the soil environment.
And that was maybe a maybe there is no good answer from from Weed Science perspective at this point, but yeah, as I was thinking through how this might look in the US, right? So we have some conservation tillage systems and how the agencies in charge of kind of classifying that would look this. In my mind, it sounds like as long as you have minimal weeds, and you're you're still going to be under the threshold
for a certain percentage of disturbance. I know there's that conversation has even begun Australia for people adopting these systems, or if it's still kind of trying to work in how the systems will work, and we'll figure out definitions about things like conservation tillage within the system later.
Yeah, so the Australia has probably been focused on no till and Conservation Cropping for three decades now. So we've got really high adoption rates. It's in the 90% of growers we call themselves conservation croppers. The challenge, the number one challenge to the that
Conservation Cropping and no tillage has been weeds. And whenever a weed problem has gotten out of control, the first thing growers turn to is cultivation, because they really don't have an option and and I guess I'm saying that in that it's a you have to have a means to an end, even though you've
got this. Context of very conservative cropping and minimal soil soil disturbance, at times, you have to break that rule and and do something to get on top of your weed problem, to get back to a more more Conservation Cropping program.
And so I guess what we're advocating with the targeted tillage is that before you get to that point of where the weeds are just out of control, and you have to resort to something drastic, like a major intervention, use alternatives to try and target the weeds with an effective tillage based system. That's some soil disturbance, but it's not field
wide. It's, you know, only two to 3% of your entire field is is actually disturbed, still fits within you, your Conservation Cropping context, and still allows you to persist with your conservation focus in the production system.
That makes me think of another question here. So sometimes in these no till or Conservation Cropping Systems, folks will also use things like cover crops. So in those situations where maybe we haven't planted and it is sort of a fallow situation, but we have a cover crop that's terminated and maybe dying by this brown would that interfere with the ability to get in and use a tool like this when you have some level of residue in your field?
Yeah, well, potentially, depending on the level of residue that you've got. So if, typically, we see that if you got high levels of residue, you don't have that many weeds, because the residue actually suppresses the weed growth. If it's a particular if it's a cereal residue, and it's high levels of residue on the soil surface, it can potentially
interfere with the weed chipper. But for non cereals, so legumes or oil seed type residues and reduce or reduce cereal content, that there's less of an issue for restricting the action of the weed chipper. But yeah, it would cause some level of interference, but not overall prevent weight control efficacy, I guess, would be the point.
Well, if I remember earlier, you said that some of these folks can also kind of fine tune the the hydraulic pressure involved in it, so maybe you could kind of Jack the pressure up if you're in a high residue situation.
Yeah, probably maybe a bit more pressure, but maybe a bit more sharper cutting blade to slice through residues. To be honest, we haven't really come across really high residue situations where we've needed to use it, either because there's hardly any weeds or no weeds, or that farmers just haven't been able to reliably achieve really high levels of residues in their
fallow phases. It is a challenge being able to get high levels of residues from cover crops and from previous crop residues, to get them to be retained on the soil surface, particularly in the areas where we're focusing on the fallow weed control, which is northern New South Wales, Southern Queensland, summer dominant rainfall areas. They're the they're the areas
where they do they really need the fallow weed control. And yeah, the residues, they break down so quickly in that environment, it's, it's hard to keep that residue on the soil surface for any period of time.
We touched on this a little bit. Sounds like you have a lot in the works in terms of next steps. But could you walk us through some of maybe your short term and long term research goals, looking at targeted tillage and how we can use them?
Yeah, sure. So the the Well, the short term goal is to try and get the weed chipper commercialized. It's, it's a commercialization is a real challenge. In Australia. We have little or no machinery manufacturing. Most of the
implements are imported. And we have the only these small engineering firms, or comparatively small engineering firms that produce some implements, but they tend to be risk averse, and so something new, like a weed chipper, is is a little bit maybe too No or has been too novel for them, but we're still hopeful. There's definitely farmer demand. So that's that's our goal for the short term is to try and get this to be commercially available so that there can be
some can get it into the hands of growers to use. The longer term goals are really about the row cropping implements. So the the active tool design system, it is quite a lot of novelty. About it. It's, it's an electrically powered system, which is very novel for agriculture. At the moment, the the industry is going electric. It's, it's, everybody's forecasting that it will be an electrified implement industry in the not too distant future. So we're sort of catering or
directing our research towards that. So a little electric motor that not only dips the paddle in, but actually controls the
speed of release of that paddle coming out of the soil. So there's a little engineering, a little bit more engineering development to go on with that system, but the agronomic development is really about proving its efficacy in row crops such as cotton and sorghum, and then potentially expanding its use into into more conventional growing crops to see if it has a role there.
Do you have any final thoughts on this, or Joe, any any final questions that we wanted to ask? Michael, I'm
going to the question side. My mind's just racing now of how we're and a lot of our no till systems. We're doing these fall residual applications, knowing that we'll have some weeds in the spring, and thinking how this could potentially be implemented, but we still a paraquat as a big hammer for that spring burn down. So we're, we're probably not there yet, but I'm just, you know, that's where my mind was cycling. So no questions at this point. My long winded way of saying that,
yeah, I'm not sure. I guess what this looks like in your region. I know in certain parts of our state, we're seeing an uptick in some non GMO organic interests. And so I see something like this potentially filling a need in some of those systems as well.
Oh, the the the end crop, row crop option that's Michael described, they're still kind of working on. Would would have high demand the tillage part, or the tillage the the fallow part, that'll be a select few people working in our region. But I know if Sarah was on, she's got a different story with or if I go west of Montana, there's, there's definitely some no till fallow out there, so not too far from my region, from being in high demand. But I'm thinking if thar growers in in
crop option for row crops would be the cat's meow. I
can definitely appreciate that we did. We did spend quite a bit of time thinking about the US that, because the US has manufacturing, right? We were hopeful that we could get a some weed chippers into the US so that we could prove the opportunity for a lesson to fallow. But yeah, in exploring that opportunity, we did, we did see that. We did learn that there's limited opportunities
for fallow weed control. There may be some opportunities for pre seeding weed control, but yeah, row cropping is probably our next option for trying to get some sort of targeted tillage action into in the US systems,
and something since I, I'd spend some time up in Canada now where they don't have paraquat, and we're, we're at a inflection point with some kosher populations, where that pre seed option could be very Big for some of those no till producers up there, where you don't have many herbicide options, that pre seed option will definitely be something to consider.
So there's a lot to be excited about, I think, for for where the future of this, this work, and its potential implications for weed management command to play, and we
understated it, so we will have the video linked in the show notes. As someone who likes equipment, watching this video is it's just fascinating to watch too. We're kind of talking the science and how it works behind of it, just watching these little times drop and kill weeds. It's it scratches a certain itch in my brain.
Well, it's just it's so gratifying to see a weed get blasted out of the soil. It's a beautiful thing,
a lot more immediate gratification than watching it die slowly, like glyphosate.
Yeah, exactly.
Yeah. So, Michael, if folks want more information about this, is there, is there a website or somewhere you can point folks to read more about this, aside from the video?
Yeah, that's a good question. Melissa, I guess there's no there's not a specific website set up with information. They could probably search targeted tillage on the on the web and find some information there. There is a journal paper that sort of talks about how the system functions and operates and its weed control efficacy. But yeah, there are. There's plenty of instances of the videos available on the web of the. Of the way chipper and targeted tillage.
Well, thank you for joining us today. Michael, it was fun to chat about this technology and to the listeners. We hope you'll tune in next week to the war against weeds podcast. Thanks for tuning in. Just a reminder, you can find this and other podcasts and resources on the crop protection network. This network has a host of information from extension programs across the US about all things pest management. We hope to catch you next week on the war against weeds Podcast.