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Mar 7, 2024

Intelligent or sensor-controlled sprayers have the potential to improve pesticides application efficiency, reduce labor, and lessen waste. Brent Warneke, Senior Faculty Research Assistant in the Department of Horticulture at Oregon State University is testing LiDAR sensors that can sense a plant and adjust the amount of spray based on the coverage area needed. Brent also addresses the best time to use biologicals based on disease pressure, the benefits of drones in farming, and simple ways to improve spray efficiency with an air blast sprayer.


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Craig Macmillan  0:00 

Our guest today is Brent Warneke. He is senior faculty research assistant in the Department of Horticulture at Oregon State University. And today we're going to talk about some really cool stuff and agricultural technology. Thanks for being on the podcast, Brent.


Brent Warneke  0:11 

Hey, thanks for having me.


Craig Macmillan  0:12 

I saw you speak at the 2023 Sustainable Ag Expo in San Luis Obispo. And I was very inspired by your talk, I thought things that you were doing were really interesting. And I thought your message is really, really great, what kinds of things you've been working on.


Brent Warneke  0:25 

I've been in this position at Oregon State University for the last five years. And we really started with investigating this sprayer, which we'll get into called the intelligent sprayer, and how it has potential to increase efficiency in terms of pesticide applications, from everything from labor to spray volume to pesticide quantity, and waste. And that's something that we've covered and in a lot of different ways that we'll go into here.


Craig Macmillan  0:55 

And so, you know, obviously, this is a viticulture oriented show, but you've done this in other crops as well.


Brent Warneke  1:01 

Yes. So I work with specialty crops in general, the kind of main categories that I focus on are wine, grapes, blueberries and nursery crops.


Craig Macmillan  1:11 

Cool. What is an intelligent sprayer? Let's start there. What is it? What's it composed of? How does it work? What are the benefits?


Brent Warneke  1:19 

Yeah, so the intelligent sprayer is one of a group of sprayers that I termed sensor controlled sprayers. These are sprayers that have sensors mounted on the sprayer, and they're able to sense objects in our in our case plants, and adjust the amount of spray they're applying based on those, what they're seeing. And the intelligent sprayer is is a kind of more advanced sprayer that uses a LIDAR sensor, which is a laser sensor, that's able to scan the plant canopy with millimeter resolution, and adjust is it spray very finely based on the canopy density that it detects.


Craig Macmillan  1:59 

Tell me more about the sensing aspect of it. So LiDAR, if I remember correctly, it's the same concept as radar. Only light is the key, the laser, the laser goes out and bounces back. Is that right?


Brent Warneke  2:12 

Yep, so a lot of these sensors use what's called time of flight. So they'll emit a beam of light. So in the case of a LiDAR sensor, it's a laser beam. And then it detects the amount of time it takes for that beam to hit off of the object and come back to the sensor. And what's cool about this LiDAR sensor is it scans a 270 degree field of view, it's able to scan basically almost through, you know, fully around the sensor itself. And out up to about 100 feet is the maximum that it can see. But you're able to set the various widths and areas that you want the sensor to focus on, for doing your precision spraying.


Craig Macmillan  2:55 

Is that 270 degrees? Is that vertical or horizontal? I mean, is it scanning up to capture canopy? Or is it going side to side to make a map, how's it work?


Brent Warneke  3:02 

if 270 degrees would be kind of three quarters of a circle, and the blind spot of the sensor would be kind of pointed at the ground. So if you can picture an arc going kind of from each side of the sprayer up and around, so it can see vertically above and also horizontally out up to about 100 feet from the sensor.


Craig Macmillan  3:25 

It's reading a plane?


Brent Warneke  3:26 

Yes it is.


Craig Macmillan  3:27 

And then it's telling the computer, there's something there, there's something not there. And then the computer adjusts how much spray or is not coming out of the nozzle then?


Brent Warneke  3:35 

Correct. So this sensor itself is a two dimensional sensor. So it scans that plane, That's 270 degrees field of view. But then as the sprayer moves through the field, it kind of creates that, that third dimension, and it's able to construct 3d representations of the canopy. And then that's what it uses to adjust the spray volume in real time.


Craig Macmillan  3:59 

How is that controlled, there must be some valves and involved in the third thing.


Brent Warneke  4:03 

Yeah, kind of where the the eyes meet the the actual controllers of the system are individual solenoid valves at each nozzle. And you can actually set the field of view or the area that each of those nozzles will focus on. You can actually tell each nozzles to only focus on a certain width of the canopy that has some a lot of different capabilities even besides what I just mentioned, there's other settings that you can use to make sure that you're kind of only targeting what you want to target.


Craig Macmillan  4:38 

Oh, okay, so does that mean that as I go along, it'll say okay, there's something above but there's nothing below so I'm gonna open the valves above not open the valves below. Or the opposite say, hey, there's less above than there is below. I'm gonna change my rate based on that so it can do it both directions and everything as you're going along.


Brent Warneke  4:55 

Yeah, exactly. A common thing is there's weeds that are below or the vines and we don't want to spray those, they're not relevant to us. So we can tell the sprayer to not regard anything that's 18 inches and below, or you can tell it to only focus on, you know, the actual grape canopy itself. So there's different settings and within the system itself, you can make different configurations for different crops or different size canopies, depending on what you're working with.


Craig Macmillan  5:26 

So something I was thinking about, as I was preparing for this interview, we've I've done a number of interviews recently around things like hyperspectral, imaging, and also just regular light. So this is a little bit different, because those things are based on color, or based on certain reflectances. This is just based on the physical presence of a leaf or shoot or branch or something like that. So it doesn't matter what color it is?


Brent Warneke  5:49 

It does not so this technology actually does not sense any colors. I mean, there is potential for that. But it just says his presence or absence. So it sprays you know, if there's a post there, or something in the canopy that's not green material, it'll spray that because it'll it'll detect that it's there


Craig Macmillan  6:07 

wouldn't be advantages to using this kind of technology?


Brent Warneke  6:11 

The advantages of these sensor controlled sprayers kind of form a cascade. So because you're using the sensors to detect canopy they apply usually lower volume than a standard air blast sprayer. And an air blast sprayer is kind of the the general comparison we always use. That's the most widely used sprayer type. What's the work? Yes, it's been the classic workhorse for, you know, 80 years. Yeah, for a long time. Yep, yeah, implementing these sensors, you start saving volume, and then that leads to fewer fill ups of the sprayer, which then leads to less labor, because you're in the field for less time, and then also less diesel, then you're also releasing less pesticide into the environment, and using less pesticides. So there's less pesticide waste as well. So there's kind of a suite of benefits that come with using these more precise sprayers.


Craig Macmillan  7:09 

And that was the next thing I wanted to talk about. So in my experience, when you're working with fungicides, in particular, it's all about coverage, coverage, coverage, right? It's all about coverage. When I use a lower volume, I am perhaps reducing the coverage that I'm gonna get. That's always been kind of the mindset, for me, at least, you know, my understanding, how does this technology overcome that issue? I mean, are we getting good coverage with this kind of technology, and then I want to talk more about the reduction in pesticide as a result.


Brent Warneke  7:38 

So that's actually a great segue, I can talk about some of the work we've done using both micronized sulfur and and also biological fungicides. So we first got this system back in 2018. And we took it as an out of the box sprayer, we're gonna see what it can do. That was our approach. And we chose micronized sulfur as our product to really investigate it with because it's a contact fungicide that you need really good coverage with in order to get good disease control on powdery mildew, which is the disease we mostly focus on. So yeah, we took it with it's out of the box sprayer settings, and micronized sulfur, and out in the field, it didn't perform as well as we were hoping it would, with a standard five pounds per 100 gallons sulfur mix rate, we took that and we decided to make some adjustments to how we use the sprayer. So we kind of tested two different things, we upped the concentration of sulfur in the tank, and then we also increased what's called the spray rate in the sprayer, which is where the sprayer will apply more spray per unit canopy. So per canopy density unit than the original lower setting. And we were able to get control that was controlled powdery mildew that was comparable to our standard airblast sprayer. So those were two adjustments that we were able to make to get to get good control. And along with that we've done coverage studies as well. And volume is related to coverage amounts. So with higher volume, you will get better coverage, you can get to the point of oversaturation, then you're not really providing any benefit. That's more of a waste situation, you may you know, you probably will still be getting good good disease control, but then you're also probably wasting materials. Well, we found that with adjusting the various settings we could get also get comparable coverage to a standard sprayer.


Craig Macmillan  9:39 

How hard is it to calibrate this kind of technology?


Brent Warneke  9:42 

You know, these these technologies these sensors sprayers I mean they're they're just sprayers like any other air blast sprayer. I like to work backwards when I'm thinking about calibration. So that really is how well is it actually covering the leaves. Using water sensitive papers is a great way to About this, you can get them from many agricultural suppliers, and just bring them out into the field. And it takes, you know, it'll take a half day or you know, it'll take a little bit of time to really dive into adjusting your sprayer. But using those cards, adjusting the air volume, adjusting the spray volume to match the canopy really has lots of benefits, in terms of streamlining spray efficiency.


Craig Macmillan  10:27 

You talked about increasing the concentration in this particular study we started with said five pounds per 100 gallon, I think, was the ultimate outcome in terms of what the concentration was.


Brent Warneke  10:37 

We jumped up to 20 pounds for 100 gallons, so four times the amount. Oh, wow, that's not to say that a lower concentration wouldn't still have efficacy. But we just jumped up there just to see how well that higher volume would work. And using the lower per unit canopy settings with at higher volume yielded similar control to our standard sprayer. So we may have been having a hotter spray mix. But then we applied, you know, quite a bit less volume. So there is a trade off there. You know, maybe with some products like sulfur, you know, there's potential to maybe not be saving as much spray pesticide material. As you know, one one would hope based on that the trade offs. But we've also done work with some trials with synthetic fungicides. And those, even with the reduced rates and kind of mixed at a standard rate, they still performed quite well. And there's been lots of other studies across the US with this intelligent, prayer technology that have found great disease control with synthetic products at those lower use rates.


Craig Macmillan  11:49 

You mentioned biologicals. First of all, why the interest in biologicals and then secondly, what did you find out?


Brent Warneke  11:54 

We've really zeroed in on biologicals over the last three years, we kind of started with sulfur and looked at that for three years. And then we transitioned over to biologicals. And mostly because there is such an interest among growers and using them. I mean, they have a lot of, yeah, they have a lot of benefits. I mean, they're typically organic, they typically have short reentry and pre harvest intervals. And there's a ton of different development that's going on in the field and new products coming out all the time. Yeah, there's a lot of interest out there. So that's kind of why we started looking into them more, just to kind of quickly go over what we found, we definitely found that some products, there's a bit of a rate response, like if you apply more of them, you might get some better control. And then other ones, we found that that's not actually as much of a thing where those lower application rates can still have fairly comparable control to the higher application rates. And then we've also found some found that some products don't don't work very well, as well. So it just kind of depends. Another kind of overarching caveat is that the disease control that you can expect is definitely dependent on the disease pressure that's present. So these products are these biological products really need to be applied preventatively. And if there's a lot of disease pressure, a lot of disease in the field, they're not going to reverse that, like, you know, many fungicides will not and these, these are the same. So that's that's kind of another caveat.


Craig Macmillan  13:25 

Right. What kind of reductions are we talking about? Like in terms of the sulfur work? You know, I think a standard application might be anywhere from two to five pounds per acre, biologicals, we're talking ounces per acre, or whatever liquid, what kind of reductions Did you see between your comparisons between the normal sprayer and the LiDAR controlled sprayer?


Brent Warneke  13:45 

So this is a it is a true variable rate sprayer. So when there's less canopy, it applies less material, and then when there's more canopy, it applies more material. So looking at a graph of how it applies spray over the course of a season, it starts out really low, so at approximately 10 to 20 gallons per acre, and then it'll slowly increase up until the canopy is full. And that can be 40 to 50 pounds gallons per acre, depending on the settings. In general, we saw it we see approximately 70 to 90% SPRAY savings in those first applications of the season. And then as the canopy fills and the maximum canopy is achieved, it's more like 30% Spray savings.


Craig Macmillan  14:36 

Ah, that's that's a lot.


Brent Warneke  14:37 

Yeah, plus or minus depending on those those settings.


Craig Macmillan  14:41 

What does that translate into in terms of like pounds of sulfur per acre?


Brent Warneke  14:44 

That all depends on your mix rate and your application volume per acre. We saw with those lower application rates that were the default when we first got it. We were applying approximately one ish pound at the beginning of the season up to to about two and a half pounds at the end of the season, with that lower use rate and five pounds per 100 gallons, whereas in Standard Mode, it was applying about five and a half pounds of sulfur per acre. And with that higher spray rate that we tested, it still started the season at approximately one and a half pounds, but then increased up to around four pounds per acre. Yeah, and that was the setting where we adjusted the spray rate and were able to get good control of mildew.


Craig Macmillan  15:30 

So if I was using a synthetic fungicide with this technology, that could be a major cost savings. Some of these fungicides are pretty expensive.


Brent Warneke  15:38 

Absolutely. What we found with the synthetic fungicides is even mixing them at kind of your standard rate. And using this technology, which applies a lower volume, we still got great disease control comparable to a standard application. In terms of spray volume savings with synthetics, there's greater potential to save on volume and wastage than with contact pesticides, which need higher volumes higher coverage to be efficacious.


Craig Macmillan  16:06 

Now, you said you started with an with an out of the box sprayer. So when you started this, it was a machine - a whole sprayer that you got. That was all constructed. Is that right?


Brent Warneke  16:22 

What I had meant to insinuate by that was it was a sprayer that we just took and used as it was, we actually started this project, kind of midway into its usage. So some folks back at Ohio State University and the USDA ARS over there, design the sprayer and kind of developed a concept model for it and prove that it worked pretty well. And then the next step of the project was to take that control system that they developed and retrofitted onto existing sprayers. And then that's where we came in. So we got just a standard 50 gallon air blast sprayer, and had this sensor system retrofitted onto the sprayer and use that system in our tests.


Craig Macmillan  17:10 

How difficult was that?


Brent Warneke  17:12 

So the retrofitting itself is not too difficult. So we have two of the systems in our research program. And one of them uses a research version of the system. The other one uses a commercial version of the system because it has since been commercialized. And when we got the commercial system installed, it only took about two hours, maybe two or three hours to get installed, and then also calibrated on to our crop that we were focusing on. So pretty quick. And the company has, you know, representatives and stuff throughout the West, and across the country. So they're able to come out and provide customer support for that.


Craig Macmillan  17:51 

So if I'm a grower, I don't need to have a master's degree in Ag Engineering to implement this kind of an idea. This is something that I can I can take and I can do myself.


Brent Warneke  18:04 

Yep, yeah, the technology is there. And there is support. And it can be run by any knowledgeable pesticide applicator one, one note, all I will say about these sensor systems is it's good to have someone who wants to use them and to take an interest in them. Because they do have more caveats than your standard sprayer would. And if you don't really put the time and really learn to use the system. You won't be able to realize its benefits as much as you potentially could.


Craig Macmillan  18:40 

Yeah, so like anything else you have to there's a learning curve, but this one doesn't seem like it's too steep.


Brent Warneke  18:43 

Yep, it's a tool. And it takes some practice, but it can give you some good benefits.


Craig Macmillan  18:49 

Are there other ag technologies out there that you're excited about?


Brent Warneke  18:53 

You mentioned remote sensing earlier, that's a technology that I'm very interested in in terms of being able to detect changes in plant canopies and use that as a way to detect what's going on in the field. I'm also interested in drones both as a way to collect some of that remote sensing data. But then also in terms of spraying. Yeah, there's there's just been an explosion in drone spraying technology. It's constantly evolving. So that's something that I would like to do some more research on is looking at how good is are these drones for spraying in specialty crops such as wine grapes, what can we do to use them in that capacity to actually get good disease control good coverage and get some good returns.


Craig Macmillan  19:45 

I remember a while back seeing it was a remote controlled helicopter that was set up to be a sprayer for wine grapes. Are you familiar with that technology for me when we're talking about.


Brent Warneke  19:57 

Yeah, I think those are maybe the yeah Mahara Maxi are mentioning, it looks like a little helicopter. And they've done tests with them, I think up in Napa and that area


Craig Macmillan  20:08 

Is it the same concept?


Brent Warneke  20:09 

It's the same concept. Most of the drones I'm referring to are kind of more the quadcopter, with the four different rotors on the top kind of your, your classical drone shape. Just larger. I mean, these things have wingspans of close to 10 feet.


Craig Macmillan  20:28 

Oh, wow.


Brent Warneke  20:29 

And they, some of them can have eight gallon tanks on them. So they're, they're pretty sizable.


Craig Macmillan  20:36 

And then we need an operator. So we need somebody who has the training and the licensing to do that.


Brent Warneke  20:43 



Craig Macmillan  20:44 

How far away is that kind of technology from being out in the world?


Brent Warneke  20:47 

Well, the drone sprayers are being used right now. There's, there's folks in the Willamette Valley, where I live in work, that are using these things in all kinds of crops. Right now, it's a very wet winter here where we live, so the fields get muddy, it's hard to get equipment in there. So that's kind of one aspect that is really appealing about these drones is that they can get into these areas that are kind of difficult to reach with tractors. And the same goes for hilly terrain.


Craig Macmillan  21:17  

Eight gallons does not sound like very much


Brent Warneke  21:19 

No, no. So application rates that these drones are targeting are typically less than 10 gallons per acre, you know, two to five gallons per acre is pretty common. I'm not by any means an expert at this point. So I won't get into the details of using them too much. But that's that's part of the impetus for the research is there's kind of there hasn't been a lot of looking into how efficacious these things are in specialty crops. So that's something that I think is a good opportunity.


Craig Macmillan  21:52 

You mentioned remote sensing. Tell me more about that. You were interested in drones. But are you interested in satellite, aerial, proximal, you know, you have some kind of a sensor on on a piece of equipment being an ATV or being on a tractor. Where does your interest lie in that world?


Brent Warneke  22:09 

I think in terms of remote sensing, I definitely have interest in the drone space. Because with that type of surveillance, you're able to get a lot finer spatial resolution than you can with, say, a satellite, I do appreciate that satellites, you can get information and data on a much wider field of view. So you can track much larger areas easier. And there's lots of different options out there that are either low cost or free. But drones I've I want to focus on a little bit more just because they're widely available. And lots of farms may already have them. And you can get very fine spatial resolution, which could allow determination of plant stressors such as disease, or localized water stress, or kind of other stresses with hopefully more precision than using satellite based technologies.


Craig Macmillan  23:10 

With things like vine stress or disease pressure, can that be combined, either directly or indirectly, in combination with your on the ground spray application that can inform what you do?


Brent Warneke  23:21 

Yeah, definitely, the spray application technology that we talked on a little bit earlier, was mostly in reference to real time sensor applications. So these are sprayers that go through the field, and adjust that what they're applying in real time based on what the sensor is seeing as it drives through the field. But there's other systems out there that use more of a prescription map approach, where they will take these remote sensing maps, or maps that are created from sensors on tractors, and then use that data to construct a prescription map. Where that is actually used. The map itself is actually used to adjust the amount of spray applied in a given area.


Craig Macmillan  24:06 

Where are we going into the future? What kind of what actually I guess what I'm really asking is what kind of projects are you looking forward to. Is the current work ongoing? Are you starting new things? Where do you where do you want to go next?


Brent Warneke  24:16 

Yeah, so our current work is, you know, as research tends to, it's always ongoing, there's other things always developing. So we're definitely continuing looking at biological fungicides. One aspect of biological fungicides that we want to delve into is kind of the compatibility. So what can we mix these things with? Is there any impact on the viability of these biological organisms that are in the products? Another thing is, are we affecting viability by using them in these various sprayers? So if we put these products through these airblast sprayers or through drone spraying systems and the like, is there any impact in their efficacy because they're expensive, and they're a lot they're alive. So those are some Some aspects. And then with the drones, I hope to do some research on looking at sprayer efficacy, specifically in wine grapes, and potentially other specialty crops as well, just to get some data on some of the spray parameters. So droplet size, volume per acre, how is that impacting coverage and efficacy? Those are, those are two things I definitely want to delve into.


Craig Macmillan  25:25 

Cool, what one thing what one message, or recommendation do you make to our listeners regarding these topics, overall?


Brent Warneke  25:34 

I would say that there's always a place to start to improve your spray efficiency. So we've been talking about sensor array sprayers and drones and remote sensing. And they're all kind of big technologies. But you don't need to worry about any of that if you just want to increase your application efficiency. I've looked and I work with other colleagues that work with spray application technology. And you can do what's called canopy adaptive spraying, which is basically working backwards from coverage on the spray cards to adjust your spray volume and the air volume that your sprayer is putting out to match the canopy. And actually looking at that in detail can save quite a bit of time and money and pesticide wastage by really targeting and matching that spray application output to the canopy itself. So that involves adjusting the spray volume using different nozzles and adjusting the air volume that's getting expelled at the sprayer by either changing the RPMs of the tractor driving faster or slower, or various ways like that. And then circling back to getting you know better good coverage. That's that will be efficacious with your products. And then on top of that standard sprayer, if you want to take it one more step, you could look into one of these sensor based systems, which could be retrofitted on your standard sprayer and increase efficiency in that way. And then on top of that, there's other autonomous sprayers that are out there that can take even more labor out of the equation. And many of those can be fitted with these sensors to increase their efficiency even more. And then if we want to take it one more step, then using some of this remote sensing data can even help streamline these things even more.


Craig Macmillan  27:32 

So there's lots of things we can do. They don't all have to be rocket science, but the science is out there. And it's coming to us in new forms constantly, which I think is really exciting. The one of the things that got me excited about your work was, like you said, you know, the basic airblast style sprayer has been around for forever. We have all gotten very used to it. That's like the base technology. And I think it's a great message to say, we don't have to stop there. We can keep going we can make improvements on what we have. And it doesn't have to be, you know, skull crushingly difficult.


Brent Warneke  28:05 

Yep, there's always some way that we can improve. Yep.


Craig Macmillan  28:09 

Well, thank you, Brent. Our guest today has been Brent Warneke. He is senior faculty research assistant in the Department of Horticulture at Oregon State University. So I'm really excited about the work that you're doing. And it's really, really great. And I hope that you can get your message out there and help people reduce their pesticide load and improve their efficiency. You know, less labor, less diesel, less water. Those are all good things. So thanks for being on the podcast. Brent.


Brent Warneke  28:34 

Definitely. Thank you very much for having me.


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