Managing Pests in Strawberries Using Predatory Insects with Andy Petran

Welcome to Farming Matters, the storytelling series where you get to hear directly from innovative farmers and ranchers across the North Central region. Each one has had a SIR grant. Today we're going to hear from Andy Petran about greenhouse biocrol. Um and I mentioned he has a s grant. Sands for sustainable agriculture research and education. and we have um outreach materials and grants for farmers and ranchers to test out innovative ideas because our mission is to advance sustainable innovations to the whole of American agriculture. So Andy, we're so glad that you could join us today. Welcome to the show. >> Thank you so much for having me and I'm excited to talk about our project, hopefully get other people thinking about biocrol. My name is Andy Petran as Liz just said, and I am the owner of Twin Cities Berry Company. We are a research and production farm that specializes in strawberry production up in Isanti, Minnesota. It's about 40 minutes north of the Twin Cities. And we focus on highdensity strawberry production. So if you can see in this picture we have in the bottom left. We grow both in the ground but also in these tunnels, we utilize the vertical space and we assemble gutters with containers in them. And then down each gutter line, we have these irrigation lines with quarterinch tubing that goes into each individual container that holds two strawberries each. And that's how they get all of their irrigation and their nutrients. And when we stack vertically like this, it saves a whole lot of space. This model, I think, embodies all three tenants of sustainable agriculture. It is economically viable for people who don't have a lot of room. It can be environmentally sustainable because it frees up land that you can take out of agricultural production and put it into things like native habitat or solar panels or just whatever you want. And it's socially sustainable because the worst part of farming for almost anyone is the backbreaking labor of crawling around and weeding. So, if you can just walk through your tunnels and harvest and weed and maintain the plants at waist level and shoulder level, it just makes quality of life so much nicer. So this system works very very well for all of those things. And we have a direct to consumer business model where we both sell our fresh berries and also we have a a vibrant cottage food uh business on the side too where we take our early week harvest and put it into jams, we put it into syrups, fruit leathers, all sorts of stuff and we're able to make extra revenue that way as well. Andy, before you move on, I'm very interested in anything that can save my back on the farm. Um, are those, while we've got this picture up, are the strawberries, so they're like waste and and shoulder lover. Are they in um soil? Is this hydroponic? What's >> Yeah, hydroponic is actually a very large umbrella term. So they are technically hydroponic because we use potting soil that we put into containers and then we have uh those irrigation lines that go into each one. When you say the word hydroponic, most people just immediately think of roots with no soil at all into this continuous liquid feed of uh water with nutrient solution going through it. That's not really what it is. It's just potting soil and then the irrigation line is on timers. So they get watered two times a day for about 10 minutes each session. So no more than 20 minutes of drip irrigation a day. So it's actually very water efficient. So much so that we got a Minnesota water quality certification from the Minnesota Department of A uh last year. And it's basically just container growing, but we stack the containers on top of each other. This is similar to growing tomatoes in containers in a high tunnel, but just, you know, utilize the vertical space a little bit more. >> Neat, neat. Thanks for clarifying. >> No problem. All right, let's go to our next slide here. So, biocrol, if you are not familiar, is basically just the scientific way of saying using beneficial insects to try to control pests on your farm. And in the open field, one of the biggest problems is you release these little buggers and they could just leave, right? They could fly away, especially if they have wings. And inside of green houses, that sort of solves that problem a little bit where you have a confined space, you have a controlled environment. And the overall goal of most people when they use biorol is to reduce or completely eliminate the use of uh sprays whether they are synthetic sprays or organically approved sprays. So that's what we're trying to do here inside of each of our tunnels. You see we have four total tunnels all the exact same type. And we used our grant project to deploy a biocrol insect called embleius swerski or as that I'll be saying for the rest of this talk for common control of pests in tunnels. It's a very widely available biocrol that you can buy from most horicultural supply stores. Uh and they are advertised for control of things like spidermitites, thris and white flies. But because we also have aphids and tarnished plant bug, also known as leus linearis, it's the biggest threat for our type of strawberry in the upper Midwest, even more than spotted wind drosophila. So I decided to test for control of that, too, just because it's unique to my plant. But things like spidermitites, thris, aphids, those are going to be common for whatever type of, you know, produce you're going to be growing in a tunnel. So our question is how much of this bio control if any is necessary for sufficient control compared to just spraying uh a pesticide in there. So how we did this is we took the as and we applied it via paper sachets and there'll be a picture of this in the next slide onto containers of plants and we wanted to see what density is necessary in order to get sufficient control. So we had four tunnels and four treatments. And those four treatments were sachets in every single container, sachets in every other container, every three containers, and then our control was no sachets at all. And we just did traditional spray. And the spray that we used was a combination of pyanic and grandivo. They're both organically approved sprays. They're very commonly used on organic farms. And over the course of two years, we recorded pest presence on a common one to five scale for the pests every single week for two years. And here's that closeup of those sachets that I was talking about. One of the ways that you can deploy as is actually through like a salt shaker where where you just shake it onto each plant and then sawdust plus the little uh predatory mites will come out. I would recommend doing that if you're thinking about it. But because it's very difficult to control how much you put on each individual plant and this was more of a scientific study, we decided to use the sachets because it allows us to control the dosage a whole lot better than just that shaker method. And yeah, the pest presence measured on a common one to five scale. We did that for two years. Each year I think we measured for about 12 weeks. And I've got two slides where we talk about our results. So, this looks very complicated. So, we're going to break it down. Let's just focus on spidermitites first. And what I have down here is look at the blue, red, and yellow lines. So, blue is sachets every container, sachets every other container for red, and sachets every three containers for yellow. Now, look at those relative to the green line, which is our spray control. And as you can see for spidermitites in 2024 and 2025 having sachets in every container at least matched and in 2024 had a little bit better control of spider mites compared to the spray treatment. We didn't have thris really either year. So we couldn't measure whether or not there was any effective difference. But for aphids, which is very common for pretty much every single plant that you grow in a greenhouse, we also noticed a very similar result where sachets every single plant or every single container had equal or better control to the spray treatment and sort of a linear step-wise regression in effectiveness as you go down to the half sachets and the sachets every third container. And if you wanted to see how that breakdown is by week, um I also have that here if you want to study that kind of on your own time. But this one here is sort of the average of all weeks each year. And this is the breakdown of weekly. And you can see the full sachets are usually in the blue here and they're kind of near the bottom for all of these graphs. And then the spray is the green kind of around where the blue is. And then the yellow and the red are almost always higher. >> So just to summarize the results, uh having an ambioski sache in every single container, we were able to actually match the efficacy of spray control for both spidermitites and aphids. Uh there wasn't enough threat presence. Maybe there it could have worked, but we just didn't see thris either year. So we weren't able to make a a valid conclusion there. as was not able to match the efficacy of spray for control of tarnish plant bug which I didn't really expect to see. I just wanted to look because that's very important for me as a strawberry grower. It's important to note that as is not advertised as being able to control ligus in any way. Um what that also means is that I won't be able to just use as for total blanket control of pests in those tunnels because legus was not able to be controlled. And right now the best control for ligus is spray. So for my strawberries I will not be able to completely eliminate spraying for ligus. I will say that if you grow in a tunnel like we do the I have to do the pyanic spray for ligus once every two weeks or so. Sometimes once every three weeks depending on the on the intensity of the presence if you grow in the open field in an area where ligus is common. If you're near an alpha alpha field or something where you have a a native host, you'll have to spray multiple times a week, every single week. So just having growing in those tunnels really really tamps down on the amount that you have to spray doesn't completely eliminate it. So we're still on the quest for bio control for ligus bug. Could be another project down the line. Who knows? But so that's good news. If you don't worry about ligus and you only worry about spidermitites or aphibs, you can have essentially the same control as spray by deploying these sachets in every single container. The economic drawback is for us in every single container. It cost about $359 per tunnel and our tunnels were 16 feet by 100 ft. And a spray control it was only $83.25. So, for spray control, it was uh 4.6 times cheaper to use spray compared to bio control. And that sounds like a lot. It was $300 per tunnel to use the as compared to the sprays. Um, but if you think about it, that's really not a whole lot in the grand scheme of most farms business models. And I think in my grant write up, I said that let's say you are growing a crop and you get something like 3,000 pounds of that crop out of your tunnel and you charge $5 per pound. If you just crank that up to $510, it'll more than cover the cost of the bio control. Then you can also advertise it if you want to go into the marketing side of things as totally spray free. People are more than willing to pay more for a totally spray-free product, especially at farmers markets where there's a naturally higher willingness to pay. And you could probably even make more money. You can go past that break even point. And so you can give consumers a product that they want and you can make more money by using the bio control even though the input cost is a little bit more compared to sprays. Just something else to help you stand out as a grower. I would recommend now that we know that every single plant or every single container is the most effective way going forward. I'm just going to be using that shaker uh and shaking the as on all of my plants because it takes a lot less labor when it comes to applying those little sachets and then removing all of those sachets and disposing of them. If you just use the shaker, it totally eliminates almost all of that work. Something that I didn't measure that's also important to think about is that you have an economic cost of the labor of applying those sprays maybe every single week in your tunnel or tunnels. Whereas with the bio control, it's just a one and done. You you apply it and then you don't have to worry about it for the rest of the season for most bio control solutions. So there's definitely a labor savings there too. And maybe that makes up for the extra cost. It depends on what whatever your labor costs are. So for future work, I would think that combining multiple biocrol options, so having more of a holistic solution within the same tunnel, you can maybe get total pest control for whatever plant you are growing and achieve uh a complete elimination of sprays, which is really desirable. It's what most small growers I think would would ideally want to do. and looking at this for different crops to ensure that the control is similar among different plants. It worked really well for us for strawberries, but maybe it wouldn't for tomatoes, maybe it wouldn't for lettuce. There's no way to know because the the grant only looked at the crop that we were growing on our farm. So just validating our results among different crops, different areas would be a good way to verify whether or not this is a broadscale solution or something that only works for our specific crop. And I think that's a quick synopsis. I don't know if that was quick, but it was exciting and I learned a whole lot and I hope that other folks will be able to gain some insight from the work that we did here, too. Andy, that was great. Thank you. >> Thanks. >> Um, really neat to see that. And yeah, you stole my first question right out from my mouth, right? Which was labor, right? So, um, how long do you think it took you to deploy the sachets? And how long for the shaker instead, would you guess? Like for let's say for a whole tunnel. >> Well, for the sachets, I would say it was about an hour per tunnel to deploy them for that 16 by 100 foot tunnel. So about four hours total for our or three hours because one of them wasn't sachets at all. >> And for the shaker, I imagined it would be, you know, 10 minutes. >> Wow. Okay. >> You just go by and you just you literally are just shaking as you go and then those the little guys are falling out onto your plants. And another big thing is that you don't have to worry about the cleanup at the end of the year. And sometimes the sachets fall off the plants and then you've got sachets on the ground and it doesn't look nice. >> Aesthetically, having the shaker I think would be a superior option now that we know, at least for our crop and hopefully for a bunch of people's that uh just applying on every single plant is is good for sufficient control of several different pests. >> Neat. Okay. And so then is this something you have to do once a year every year? um like do or can the mites establish a breeding population inside a tunnel? >> So I asked the horicultural uh contact that I had about that specifically and they recommended redeploying every six weeks. Um, we didn't do that. And we, if you, if you look at our weekly breakdown, you can see the the control seemed to stay throughout the entire 12week season that we had. And that may just because, like you said, we they were able to get several generations in as long as they're protected and doing well. and they probably got their water from from the from the daily irrigation and they had all the food that they needed because they were feasting on the spidermitites and the aphids. Um, but the horicultural supplier that I had, BFG, recommended redeploying every six weeks and we did not do that. So, and still observe, you know, pretty good results over the course of two years. >> That's neat. Yeah, I wish we could go back and have that exact labor data because when you build that in, right, instead of spraying weekly, um I think it would be way closer. >> Yeah, exactly. And like just rough in my head right now, you know, a weekly spray for every single one of my tunnels would probably take me an hour a week. So maybe 12 hours of extra labor to do that with a with a battery pump backpack sprayer. >> And you know, you you pay someone 20 25 bucks an hour, you know, depending on where you live. And that could more than make up for the cost of the extra bio control. >> Yep. >> Up front. >> When you were measuring for pest presence, what were you looking for? Were you counting numbers of critters? Were you looking at the plant quality? Um, how do you measure that kind of presence? >> Good, great question. So, we measured in two different ways. One, we had sticky traps. So, those yellow sticky traps where you can just measure whether or not the pest is present. Um, that's kind of how we knew that the thris were almost never there. Uh, and then most pests, at least from an academic sense, have their own what they call a common one to five scale of damage. So in addition to their presence wasn't really measured in that one to five scale because sometimes you can't see them. Sometimes they're so small you can't see them at all and it's much easier to see what they leave behind rather than them themselves. So for something like spidermitites, the one to five scale is uh no presence at all. To spidermitites, at least on strawberries, they will start leaving sort of brown tips on the on the tips of each uh lobe of the leaf to eventually seeing literal spider looking webs on the on the plant. And then you'll start to get leaf curling and eventually complete scinessence of the leaf. if the if the spider mightites take control. So you sort of go from the one of just seeing a little bit of the presence to five complete uh leaf and sometimes even uh fruit death as a result of them being there. And you can look up for your specific pest which one to five, you know, stepwise progression there is. And it's pretty widely available. You just have to do a little bit of digging to find it for each one. I I started out, you know, without any land or capital in my inheritance pipeline in in, you know, beginning farmers. That's the number one hurdle is land access. And one of the hardest things to do is going from just renting land to being able to buy a farm of your own. And we were fortunate enough to be able to do that. And if we want to maintain the security and future of this vital piece of American agricultural fabric, I think we have to do a better job of developing new ways of growing that's actually available and affordable for those folks that can't afford $12,000 an acre for a new farm. And hopefully with projects like this and with NCR Ser funding so many great projects, you know, year after year after year, it can create a database to help growers go from having nothing at all to owning a piece of land that they can grow their own way and act out their philosophies. That is beautifully said and maybe the perfect note to end on because um that's that's what we're trying to do. Um, and you're right about the database. There are loads of good um, projects like yours that lay out here's how to do this thing. Uh, we just had an interview with a dairy farmer who figured out for his s project how to build a lowcost milking parlor that someone on rented ground could tear down and put in a different spot if they needed to. Um, >> that's why we grown caterpillar tunnels. I mean, I started renting and I'm still doing it just because that's the easiest way for people who don't own land to get started with controlled environment agriculture. >> Excellent. Well, thank you for sharing all this with us, Andy. This was great.