Knocking the wind out of soil diseases

In this episode we talk to Anna Testen and Bob Philbrun, from Ohio, about a method for directly competing with and destroying soil diseases by encouraging a special group of microbiology, called anaerobes. Like day shift and a night shift clocking in and out, the anaerobes rule with oxygen is removed from the soil, leaving behind a tilthy planting medium wither fewer plant disease-causing pathogens.

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Ben (00:14):
Welcome to the Vegetable Beet. My name is Ben Phillips and I work with Michigan State University extension.
Natalie (00:19):
And my name is Natalie Hoidal. I work with the University of Minnesota extension.
Ben (00:24):
We've been doing this podcast over the last few years, and we're changing the format a little bit for this season. We're going to do some pre-recorded interviews in a three act style where Natalie and I will introduce an episode by talking about why we decided to do it. It might not be us doing it, but we will introduce it. Then we'll have the second part, which is the actual interview performed by us or other people. And then the third part will be a wrap up. What did we learn? Where can we go from there? How are we doing this, Natalie?
Natalie (00:52):
This podcast is brought to you by the Great Lakes Vegetable Producers Network. It was kickstarted by the North Central Integrated Pest Management Center. Our license for Transistor is held by the University of Minnesota extension.
Ben (01:04):
You can listen to this episode and all the rest at glveg.net/listen. Enjoy the show. Hey Natalie, how you been?
Natalie (01:23):
Hi, Ben. Great. How about you?
Ben (01:25):
I've been pretty good. I got to do this interview that I've been really excited to do with some folks from Ohio. I interviewed a woman named Anna Testen from the USDA ARS.
Anna (01:38):
Anna rhymes with banana. Unless you're British, they just say it however they want.
Ben (01:42):
And a guy named Bob Filbrun from Earthen Goods Farm in Ashland, Ohio. The first time I wrote a note to you Bob, I wrote Filburn instead of Filbrun.
Bob (01:53):
Oh, that happens all the time.
Ben (01:56):
He also is the farm manager at the muck crops research station in Willard, Ohio, but he's mostly in this interview as a farmer who grows greenhouse crops and he uses this process called anaerobic soil disinfestation. It's a mouthful.
Natalie (02:15):
Yes.
Ben (02:17):
Anna does research on this and so she has been working with Bob as a research collaborator, along with a bunch of other growers in Ohio to talk about this process in which you can basically clear the soil of pathogens, because it's super common in a hoop house to use the plastic for as long as you can use it for and grow the most profitable crops year in, year out and after about year three, you really start to notice the decline and by year eight, it's almost a joke. Sometimes they just don't do anything. It's because of a buildup of a few things.
Ben (02:50):
The diseases are corky root rot, black dot root rot, verticillium wilt and also root not nematodes. At least that was what was found in Ohio in a big survey, across several growers. Anna started to look at this technique against those diseases and that's what the show is about. It's about what it can do, how you do it when and why so here it is.
Ben (03:18):
I guess we're here to talk about ASD and grafting. Maybe we can eventually get to it. It's been fun catching up with Ohio people. What I'd like to start with is with the question to Anna, because you had a neat workshop last year, last August about ASD. I think it was at your farm Bob and it was with Central State University and it was demonstrating this process in a way that I'd never actually seen it in real time. I'd like if you would be able to describe it in words, like what is the ASD process and what does ASD stand for?
Anna (03:55):
Yeah. ASD stands for anaerobic soil disinfestation, which is a very fancy name for a somewhat simple biological process of managing diseases. ASD is a three-part process in which we amend soil with a carbon source like wheat brand or molasses. Then you irrigate that soil to saturation and then you cover that soil for several weeks. What we're trying to do in this process is leverage the power of microbes that live naturally in our soils to combat soil-borne pathogens. What happens in ASD is that these soil-borne microbes... Sorry, I love soil-borne pathogens so much, I always say so.
Anna (04:40):
What happens in ASD is that these natural soil microbes will start to break down that added carbon source, which is food for them. When they break it down, because we've saturated that soil, there's not much oxygen available so then they shift to using anaerobic types of digestion. In those anaerobic processes, there's a lot of nasty byproducts that are produced like acetic acid, butyric acid. We have volatile organic compounds. It's the lack of oxygen and all these nasty byproducts that are produced that kill off soil-borne pathogens.
Ben (05:15):
Okay.
Anna (05:16):
I like to think about anaerobic soil disinfestation as a type of biological control. We're using beneficial microbes to control diseases in ecosystems.
Ben (05:27):
Yeah, it sounds like it's a bit of a biofumigation type of situation too, but when I think of fumigation, I think of a gas and this is actually the absence of gas.
Anna (05:40):
Yes.
Ben (05:40):
So yeah.
Anna (05:41):
There are gases produced like methane, and carbon dioxide, but what makes ASD different from bio fumigation is that we have that added flooding and also the carbon sources that we're using. Usually in a bio fumigation, we're using something like a mustard or abrasipa. Then you get the production of toxic compounds called isothiocyanates. In the absence of water in the soil and with tarping and those isothiocyanates will volatilize and kill off soil-borne pathogens. There's some interest you can use these mustards as carbon sources in ASD, and maybe get a little bit of a combined impact. But that's how those two processes differ is really, what carbon sources you use? Then the presence or absence of water.
Ben (06:28):
Okay. Okay. These microbes that enjoy an environment that doesn't have any oxygen in it, is that their prime way of operating or do they switch from breathing oxygen to not breathing oxygen or is it like a moving in of organisms that can tolerate that environment? Do they like to move in?
Anna (06:51):
Yeah, that's a really good question. One thing I love about ASD and why we have lots of things to still study is the microbiology and ecology, changes in microbial interactions that we see in anaerobic disinfestation are really complicated.
Ben (07:06):
Okay.
Anna (07:06):
When we first put that carbon source in soil, there's still a bit of oxygen left. We have some really fast colonizers like some fungi and some quick growing bacteria, like pseudomonas that start to break down those carbon sources. Then as that environment starts to shift to anaerobic, we have microbes that can operate and without oxygen, like bacillus. Those will start to take over, and then when we go fully anaerobic, we have our true anaerobes like clostridium that start to dominate these populations. The biology of clostridium is really wacky. We produce all kinds of nasty byproducts that are what we want to control these pathogens.
Ben (07:50):
Is clostridium the same thing we hear about when we're canning food?
Anna (07:56):
Yes, it is.
Ben (07:57):
Okay.
Anna (07:59):
As humans, we do focus a lot on the negative of the microbial world and the majority of clostridium just like the majority of microbes are non-pathogenic.
Ben (08:10):
Okay.
Anna (08:11):
But there are clostridium in soils, not every soil, such as clostridium botulinum, clostridium tetani that do cause human diseases.
Ben (08:21):
Okay. I'm not trying to freak anyone out. I was just trying to draw connection.
Anna (08:24):
Yeah and that's where most people identify, are familiar with clostridium.
Ben (08:29):
Okay. Okay. How long has ASD been a thing?
Anna (08:33):
Yeah. ASD was originally developed in Japan and the Netherlands in the late 1990s.
Ben (08:40):
Two separate? Japan and the Netherlands?
Anna (08:42):
Yeah. Two separate regions of the world that really interestingly kind of came up with the same process. I mean, Japan, Netherlands, total opposite side of the world but really when you read the original papers, what they were trying to do was... We knew that flooding would reduce soil-borne diseases, but not very well. We knew that organic input such as cover crops or crop residue can reduce diseases and we know if you tarp soil and keep it warmer and solarize it, that can reduce diseases. Both sets of researchers thought, why not all of these? Kind of combine them into one treatment, then you get this really unique biological situation in which this combination of treatments works way better than any individual component of treatments.
Ben (09:30):
Okay. I see. When you mentioned the flooding being a technique in itself, I recognize that one of the factor, one of the things that ASD seems to treat are nematodes and flooding alone, I would think would make that worse. At least, that's my observation on some of the muck soils in Michigan where carrots are grown, where the water gathers is where the nematodes tend to be the highest pressure. I guess then when you combine that with this carbon source and the covering, that it ends up reducing them, is that what I'm hearing?
Anna (10:12):
Yeah. The thing with flooding and water is, while that is an effective treatment for some soil pathogens, like you've said, it's not effective for all. Why flooding is so difficult is usually most of these soil warm pathogens they're used to surviving in low oxygen conditions and water is just a great way for them to spread.
Ben (10:32):
Yeah.
Anna (10:34):
Yeah, you need that additional input in these systems of that carbon source combined with your indigenous microbes in the soil to make those nasty byproducts that really are what most is makes ASD most effective. Interestingly, root-knot nematodes seem to be the most sensitive to anaerobic soils infestation.
Ben (10:53):
Okay.
Anna (10:53):
We've gotten really good reductions in root-knot nematodes, even at really cool soil temperatures of about 15 Celsius. We're talking mid 60s Fahrenheit, really cool soil treatments.
Ben (11:07):
Okay.
Anna (11:07):
The nematode will still be killed off.
Ben (11:09):
Okay. Okay. Now Bob, how long have you been using ASD then knowing that, or how did you learn about it and then why did you choose to run with it and when did you start?
Bob (11:25):
Anna may have to help me with this a little bit. I'm trying to think whether...
Anna (11:29):
You participated, I think, in our 2016 round of experiments.
Bob (11:35):
Yeah. Kind of through Anna, of course. We were having some issues with tomatoes. We hadn't been growing tomatoes, I don't think too long, but saw the potential. Had heard the stories of other high tonal growers with the lack of rotation and that single crop. We just saw in the rise and we were going to have issues. We were trying to be a little preemptive, proactive. Anna was working, I think with some mennonite growers, maybe two at the time.
Anna (12:13):
Yeah. We worked with a lot. Most of our growers are Amish and conservative Mennonite.
Bob (12:18):
We thought we would kind of partner up as well to see how it, of course our soil type is very different in our high tunnel. Of course, everything was in field production here at the research station. It wasn't in a controlled environment like our high tunnel more so. Yeah, we were eager to participate and it was really interesting to see kind of the differences in how it worked and kind of saw some of the challenges and try to figure out how it would work into our cropping system. Yeah, it gave us a chance to kind of play with it and see where it would fit in and how it would be beneficial for us.
Ben (13:00):
Okay. You have one tunnel?
Bob (13:02):
Yeah. We just have the one tunnel. I'm trying to think, it's like a 25 by 50. It's not that big, just for us to do enough tomatoes that we have a little roadside stand. Then we also sell a few through one of the local produce market, have one specialty retail outlet that we'd stock as well through the season. Obviously, we were trying to hit the early market, so that for us, and initially we thought maybe we would try and combine it with some greens production. That was the other thing, trying to figure out how ASD fit in, if we were going to follow tomato production with greens, how could we fit ASD into that very narrow window between those two crops?
Ben (13:55):
Yeah. You've got a tight turnaround.
Bob (13:58):
Yep.
Ben (13:59):
Yeah, I've got a lot of Amish and Mennonite growers here in Michigan. I think most would identify as Amish and they do hoop house tomatoes for auction and they're chasing the early market as well and then they all end up with the glut in August and some of them do a second planting that they take through November to see the price go up again a little bit, but many of them don't. Then they'll retire it August or September. Then they'll kind of just prep it for winter. Sometimes we just cover crops and sometimes doesn't, but I could see. Yeah. If you wanted to then follow up with a winter lettuce or spinach crop, you've got a pretty tight turnaround because you got to get those in by like mid-September in order for them to be yep. Reaching that harvestable stage when everything just stops growing.
Anna (14:50):
Exactly. Yeah. I mean, that's a good point because the ASD treatment takes four weeks.
Ben (14:55):
Okay.
Anna (14:56):
When you talked about that glut of tomatoes in August and September, it's the same situation for growers in Ohio. A lot of times they'll just say we're done, we're not getting money from these tunnels anymore so we'll pull those crops early. That's when we'll see treatments August, September, October. Some of our growers have enough tunnels that they'll leave one out of production and then they'll do ASD when they have an opportunity within the season. Especially, the treatment is more effective the warmer you can keep that tunnel. We're still seeing good results in warmer Octobers but if you can get that in September, you're more guaranteed to have good results with the treatment.
Ben (15:41):
Do you know of anybody who will actually turn on the heater to ensure that this happens in a timely manner?
Anna (15:50):
Most of our growers, there's only been one year that we had a really cold October that would've required heaters, but I don't think the heater would get the soil to the temperatures you'd want.
Ben (16:02):
Yeah.
Anna (16:03):
Most of the time, with enough sun, if you close up that tunnel, it's going to stay warm enough during the day.
Ben (16:09):
Yeah. I think it'd be perhaps a sunk cost, I think, to heat all that air space, just to try to raise the soil temperature a little bit.
Anna (16:18):
Yeah. That's one reason why, unfortunately, in a temperate region like a spring treatment would delay your planting too much. Even with the solar radiation, you're not going to get those tunnels hot enough. Usually you're not going to get those tunnels warm enough long enough. Because you'd want soil temperatures above 68 Fahrenheit for a period of three to four weeks.
Ben (16:40):
Yeah. Yet tomatoes go in, some of them are going in March and some late February. Yeah, there'd be... Yeah, you need to get things ready for tomatoes to go in the fall, that'd be your best opportunity. You mentioned time about four weeks, and I understand that temperature plays a role here too. Can you talk about that?
Anna (17:04):
Yeah. We have found that if you can maintain a temperature of... Let me Google. Give me one second. I'll start this. All my scientific studies are in Celsius so I'm like, I'll tell you in Celsius. Hold on. Okay. We've done a study and we've found that like what most consistently gives you good results is if you can maintain four weeks of treatment in a temperature range about 75 to 77 Fahrenheit. You'll still get reduction in diseases if you have cooler temperatures but if you have cooler soil temperatures, you want to think about extending your treatment to maybe about six weeks. If you have temperatures at 68 Celsius, if you're doing an October treatment, keep those soils covered because, but microbial activity will increase as temperature increases. If we have lower temperatures, we want to give those microbes more time to do their work.
Ben (18:02):
All right. That makes sense. Yeah. We hear about that a lot on the food safety side of things, especially when it comes to like compost and paying attention to temperature and rotation of composts before you put them onto a crop that's eaten raw. Because the hotter things get the more things really cook and by cook, I mean they replicate, but then you can get to a temperature where they die off as well. You kind of have to push it, but this is obviously different because this is anaerobic. It's a little different than a compost pile, but that's good to know. Okay. When you say 75 to 77 degrees Fahrenheit, is that sort of like an average, so your nighttime can get down to mid-60s and your day times that could get in the 80s.
Anna (18:51):
Yeah. It's an average temperature. Again, you're not going to have a nice controlled 75-77, that's not realistic. If you have temperatures of in the 80s or 90s, if you keep that tunnel sealed up, that's great. Microbes are pretty resilient. They'll just keep eating away at what you've given them and they'll keep producing nasty byproducts.
Ben (19:12):
Okay. The hotter the better then?
Anna (19:15):
The hotter, the better, but if you're doing a fall treatment, it's not always realistic to get soil temperatures in the 80s.
Ben (19:21):
Okay. 75 to 77 is kind of like the lowest you want to go for that four-week window?
Anna (19:28):
It's your safe zone to get good efficacy against a range of pathogens. Like I had said earlier, nematodes, we still see reductions even at lower soil temperatures in the mid-60s, but if you're you have something more stubborn like a fusarium or a corky root rot, you're going to want higher temperatures.
Ben (19:49):
Okay. Don't bother opening the vents if it's getting too hot?
Anna (19:52):
Nope.
Ben (19:52):
Okay. Good to know.
Anna (19:54):
Leave those tunnels sealed up, make sure you're capping the ends. Make sure you've got the sidewalls rolled down. You make a giant incubator for those microbes.
Ben (20:03):
Yeah. Sounds fun. The carbon source is the second piece you said. What effect does the carbon source have? I think in the paper that you had sent to me, you were working with a wheat based product. I don't remember if it was meads or germ or bran, but then also molasses.
Anna (20:23):
Yeah. Yep. We use bran and mead. Carbon source is most important decision you can make and there are some safe choices for you.
Ben (20:32):
Oh, wow. Okay.
Anna (20:33):
First thing I want to talk about for carbon sources is the rate. In ASD, we have to use a pretty high rate of carbon source. We found that nine tons per acre will give us consistently good results. That's quite a bit, but if you're looking in a high tunnel, it's not as much as you think. That's why ASD works really well in high tunnels is because you have a limited area to treat and so that helps reduce your costs.
Ben (20:59):
Right.
Anna (20:59):
These high rates of nine tons per acre, pretty consistently reduce diseases. We have found that a half rate of four and a half tons per acre does still reduce disease, but not to the same extent as that high rate of nine tons per acre. If you want to do ASD more frequently, say every year, every two years, you might consider using that lower rate to save money.
Ben (21:23):
Okay. Bob, what kind of materials have you been using and what rates have you observed or sort of fallen into as like a regular practice?
Bob (21:34):
We follow this rates that Anne is recommending. Now we started, I think in the first year or maybe two years that we did it. I believe we used wheat brand. Then since then we've transitioned, I think over the last four years or whatever, maybe more we've used the wheat meads. Of course, we've always used the molasses. But yeah, we've always followed the rate that Anna has recommended.
Anna (22:04):
Yeah. Wheat bran and wheat meads, we've consistently gotten good results from both of those carbon sources. Nutritionally, they're very similar, but wheat meads are about half the cost of wheat bran. Okay. A lot of times it comes to what can you find at your local feed mill? For most growers in Ohio, they can get meads and it's a lot cheaper for them to apply the treatment with meads.
Ben (22:29):
I'm wondering if there are other byproducts out there of any volume. Like in Michigan, I'm thinking sugar beet pulp might be one that you'd have to kind of figure out how to like get into their system. Because they do particular things with it. It ends up in like these settling ponds and stuff and I don't know then how you recover it. You'd have to get creative, I guess.
Anna (22:52):
Yeah. That brings up a good point. Most of the carbon sources we use in ASD are agricultural byproducts, because you're using it at such a high rate, you want something low cost and that's easy to get locally. That's why even though ASD is used in California and Florida in the US. When we started looking at it in the mid west, we had a look at a totally different suite of carbon sources that we had available to us here. You know you said in Michigan, you have this unique product in Ohio. We also have unique products like tomato palmas, tomato processing. Processing tomato industry in Northwestern, Ohio. There's lots of unique local products that could be used.
Ben (23:34):
Yeah. Yeah. Okay. When I'm thinking of like wheat meads and wheat brand, I'm thinking of a dry product and some of this other stuff like the tomato palmas and the sugar beet pulp might be more on the wet side. Would you then reduce the amount of molasses you would add with a wet carbon source or what do you think there?
Anna (23:53):
Yeah, so usually when I talk about that rate, I'm talking about your main solid carbon source would be nine tons per acre.
Ben (24:02):
The main solid stuff. Okay.
Anna (24:04):
Yeah. Then what the molasses role is kind of as a lighter fluid for the microbial activity. Cause you know, that has more free sugar like products that you think. Think of microbes as little tiny greedy children, they're going to go for the sugar first.
Ben (24:18):
I wonder...
Anna (24:18):
Once they start eating that sugar, eventually they're going to use up all those easily digestible. Sugars, and then they have to move on to the main course, which is your main carbon source. Now, like you said, a wet carbon source. I haven't seen any studies in the mid west, but you could pretty easily figure out how much either wet or dry palmas or sugar beet debris you would need for those treatments.
Ben (24:48):
Okay. Molasses is the lighter fluid. That's a good way to remember that. What's the rate that you would recommend there for the molasses?
Anna (24:54):
Yeah. Molasses, you can get away with a rate of one to four and a half tons per acre. That's again, in addition to your nine ton per acre of solid carbon source. Depending on temperature, if it's a little bit colder, I would air towards using a higher rate because then you have more sugar to get those microbes going. We can see this. It's really cool when we do these trials. If we have molasses in our treatment, those treatments are one to three degrees warmer than our treatments without molasses. You know those microbes are really doing their work when you add that additional molasses.
Ben (25:32):
Okay. Okay. That's good. Well, go ahead Bob.
Bob (25:36):
Yeah, one point just to mention and we'll get Anna's take on this. I would caution a little bit as far as the carbon source goes. I think a big consideration too, is you have to be thinking about the incorporation of that product into your soil. So that's the one nice thing about wheat, germ or wheat meads. It is, it's very easy to incorporate into that soil structure down to the depth that you're looking for now. I don't know how typically we would apply that out and then we would go ahead and use a tiller to go ahead and till that in or some sort of rotavator. We're not going that deep, we're still staying in that typical root zone for the crop. I don't know if that has any bearing Anna, when you're dealing with a wet or a more moist, I don't know, a fibrous. I'm thinking of like a beet pulp is more of a fibrous carbon source. I don't know if that's true for the product you're mentioning, but I don't know, Anna, would it be a challenge to get that incorporated?
Anna (26:44):
I mean, it all depends on your equipment. For example, the workshop we did in Bob's high tunnel, that was a really good demonstration of a small scale, high tunnel production application of an anaerobic soil disinfestation. In general, you want to work that carbon source to a depth of six to eight inches. That's, what's realistic for most growers with the tillage equipment they have. The nice bonus, if you have a liquid carbon source like molasses is that'll penetrate the soil a little bit deeper. You're getting that carbon source down to that depth of maybe 12 inches, which is great. You get a little bit of a bonus from that but yeah, it's all about adapting to what works for your system for incorporating those carbon sources. I know that's you can buy palletized sugar beet.
Ben (27:34):
Oh, I haven't seen that, but it would make sense.
Anna (27:36):
Yeah. I've seen it for sale. I mean, obviously your costs are going to go way up, but I've seen palletized sugar beet. Is it the gas that's left over from the sugar production? I don't know if that's what it's called technically but...
Ben (27:50):
I'm not sure.
Anna (27:50):
They are kind of like an animal feed. This is one way for people to find carbon sources. It's go to your local feed store or feed mill.
Ben (27:59):
Yeah.
Anna (28:00):
Look at what they have available for animal feed.
Ben (28:03):
Okay. Okay. Oh gosh. I had a question. The molasses and incorporation, what kind of effect does that have on the equipment that you're using? I'm thinking of molasses as being sort of a sticky, maybe frustrating material to work with in that way. I've known it. I've seen it used in sprayers a lot. I've it also seems like an Amish type of thing. I'm not sure why it is. I don't hear many other people talking about molasses applications or the agricultural uses of molasses, but in that community, I hear about it fairly frequently, usually through a sprayer. But getting it incorporated with metal tools, rotational tools, I'm just curious what the effect is like.
Anna (28:49):
Molasses is always an adventure to work with. Again, it's based on scale.
Ben (28:55):
Okay.
Anna (28:56):
In Bob's high tunnel. We can pretty easily spread the molasses. One, always make sure you dilute your molasses because you're not going to [inaudible 00:29:04]...
Ben (29:03):
Oh, dilute.
Anna (29:04):
... the molasses and just dump it on your soil, that would be a mess. We suggest diluting it one to three or one to four with water. It goes into the water pretty easily. Then in a, in a high tunnel, Bob sized, it takes us what? Maybe 15 minutes to put it in water in cans and just walk it through.
Ben (29:22):
Okay.
Anna (29:23):
Now if you have a lot of tunnels, you're not going to want to do that. I've seen suggestions of putting it in backpack sprayers, putting it in like a sprayer cart but it's molasses. It's great at clogging things.
Ben (29:38):
Does it settle out in the column as well?
Anna (29:40):
It does.
Ben (29:40):
Okay.
Anna (29:42):
Yeah. If you can keep that stirring, that's great. Molasses is a bit tricky. What you want to do in ASD is you want to make sure that you have that first solid carbon source tilled into the soil. If you're going to treat beds, you want to have your beds formed at this point. Then what you'll do is you come back and put the molasses either onto that flat ground or the beds.
Ben (30:06):
Oh, you're not actually then reincorporating?
Anna (30:11):
No. The nice thing about it being a liquid is you're just going to rely on that liquid to soak itself into the soil.
Ben (30:15):
I see.
Anna (30:16):
Yeah. Then when you add your irrigation later, that'll also help the molasses penetrate deeper into the soil. Somebody asked once if it would be washed away. I was just like, "Well, think about sticking molasses into them." It's pretty good at sticking in your soil. It'll get taken down the soil profile, but you're not going to wash it away when you add your irrigation in these systems.
Ben (30:41):
Okay. Surface applied molasses, not incorporated. That was great to hear. I was a little worried about what the tiller would look like at the end of that.
Anna (30:52):
Oh yeah. That'd be amazing. You should be more worried with your boots look like after molasses.
Ben (30:59):
In the video of your workshop. I saw you went like elbow deep into some container to mix it up. Is that necessary or is that just you had to do that?
Anna (31:13):
I would recommend using like a stir stick or something.
Ben (31:15):
Like a broom handle or something. Yeah.
Anna (31:17):
Broom handles or PVC pipe is great for stirring stuff. I'm a very hands on type of woman. Just get in there and get that mixed up.
Ben (31:26):
That's great. Okay. Bob, I got a question for you then. You were part of that workshop. You've been doing this for a few years now, and I'm wondering now that it's become part of a routine on your farm. Has it resulted in a sacrifice of any other types of processes that would occur at that same time? I guess another way to ask this is, does it get in the way of other things that you'd be doing around then?
Bob (32:01):
I think Anna alluded to it earlier and I think probably other growers. We typically grow a combination. We mostly have grown determinant type tomatoes in our high tunnel. We can talk diseases in addition, but unfortunately a big problem for us has been leaf mold. We have to get varieties that are more or more disease resistance, at least toward leaf mold. We've had to use a couple of different indeterminate varieties. As you can imagine, and even a couple years with our determinate types, when it came to August, we were actually having a whole new set of fruit coming on. It's a challenge to try and figure out when that sweet spot is when price wise, your market may not be the best.
Bob (33:05):
It depends a little on your market. If you still got a decent market and prices are fairly good, it's hard to pull the plug, especially when you see a really nice set of fruit coming on. That's probably on your main crop. I find that's probably your biggest challenge. For us, we typically go into our high tunnel a little bit later. I do have heat in my high tunnel. I've got the ability to do some heating in the early months if I need to.
Bob (33:39):
While I'd like to go start transplanting in March, for us it's just not feasible with fuel costs. I generally am looking at April one. I figure at very most I'll provide some heat if necessary up until maybe a month, month and a half at most. If I do that, I'm still having pretty good production because for us, I really need to be shutting down and pulling those tomatoes by. I would like to have them out by early August, because my goal is, if we come in with greens, I'd like to have those greens transplanted in about that end of that first week for us.
Ben (34:28):
End of that first week of September, you said?
Bob (34:30):
Yep. I'm typically shooting for end of that first week of September to transplant that green crop in.
Ben (34:36):
You'd like for the majority of the month of August devoted to this ASD process.
Bob (34:40):
Yep.
Ben (34:41):
Okay. I suppose if your market was still hungry for tomatoes, one technique you might have, and many growers I work with do this. They have a field planting perhaps more than one that is really it's part of the problem with the glut to begin with because people who don't have hoop houses, they just have field tomatoes. Their stuff comes in August alongside everybody else's. That's part of the glut thing, but yeah, I guess you're not using as expensive or real estate, so it doesn't hurt as bad to want to take out the hoop house tomatoes, I suppose, if you've got a backup crop in the field, right. To keep that thing going, I could see that. Okay. I
Bob (35:24):
Probably, I would say we probably lose, I would say a good two to three weeks of good tomatoes that we lose by trying to get them out August one or very early August.
Ben (35:37):
Okay.
Bob (35:37):
On my primary crop, I would say that's, that's one sacrifice you make. Now even then on the... Trying to think then again, then on your secondary greens crop, again, you're making a little sacrifice because you're probably getting into your high tunnel with those greens a little bit later than you'd ideally like to be having them started.
Ben (36:02):
Okay.
Bob (36:06):
I can't really think of any other real trade offs other than those right off.
Ben (36:13):
On your farm, it sounds like this would be a problem every other year. Right? You do this bi-annually?
Bob (36:19):
Initially we did it annually. We were pretty much going every season. But I think, and again, Annie, you can weigh in on this. I think maybe over the last three to four years, I think in talking with you, we decided we could, we could bring that back to every other year.
Anna (36:37):
Yes. Go ahead, Bob.
Bob (36:40):
I don't know, I would assume... I don't know. Do you have numbers? Did you guys do some research on that to know how is the efficacy of the annual? Or...
Anna (36:51):
Based on what we've seen, so we did a survey of soil-borne diseases in 2017 and some of the information we got from that survey was how long have you been growing tomatoes? It seemed like it took about three years of continuous tomato production until these key soil-borne diseases. We talked about corky root rot, verticillium wilt, black dot root rot, and [inaudible 00:37:13], before those started to become a major pro problem. We're talking probably every three years, if you're using it as a maintenance treatment. Really, as Bob said, getting those tomatoes out in August, that works for him because he's got his soil-borne diseases under control now. Unfortunately, what we've seen is for growers who have a major soil-borne disease issue. Their tomatoes aren't going to make it until August. If you have soil-borne diseases at the level that ASD has now become your last ditch effort to control those diseases. It will, it'll not come back. Your tomatoes are going to lose vigor about mid-July and you're not going to have plants producing in August, unfortunately.
Ben (37:58):
That much of a time conflict there, because the tomatoes are done.
Anna (38:03):
No, when you have no tomatoes in your tunnel, there's not much of a conflict.
Ben (38:06):
Yeah.
Anna (38:06):
Especially this is how we started doing as looking into ASD in Ohio was we had two major growers and both had been growing tomatoes in the same location for eight plus years and their crop was petering out by July. First they had noticed a gradual decline in yield and then it just came that they couldn't produce that crap as long as they normally did. When I went to look at their sites, we found just this menagerie of soil-borne diseases.
Ben (38:37):
Yeah. Well, there's one comment I want to make. Then move on to another question that's directly related to what you just said. I can see one conflict at with the time of year when you have to do this. That is if you have a whole bunch of other crops and they all need attention in the field perhaps, right? There's the harvest of the cucumbers and the eggplant and the peppers and the broccoli and sweet corn and whatever else is happening. I'm curious, what time commitment it was to get the whole thing done. On your farm Bob, in that video that you put together last year, you'd said one of the pieces was about 15 minutes, but like maybe that was the molasses application but the whole thing from start to finish, if you weren't filming it for a class or whatever, how long do you think it would take?
Bob (39:28):
Well, as far as the initial gathering of supplies. You've probably got a couple hours in going to your feed store and acquiring the molasses and the carbon source once you're actually in the high tunnel and starting the process, it actually goes quite fast. I mean, for me, probably the initial step is probably the most physically challenging and that's the actually kind of... I try and go through and do some pre-tillage. I'm trying to, till out the entire, the entire high tunnel. Areas that you've used is kind of your walk areas.
Ben (40:15):
Okay.
Bob (40:16):
That takes a good bit of time trying to break up any compaction that you've caused over the pre-seeding season, trying to get that soil in a pretty good tilt, I would say. Working that tillage, a couple different directions to make sure you've got that soil in good condition. Once you've done that, which so I probably, a good hour and a half, two hours probably doing some of that pre-tillage. As far as again, the incorporation of the organic matter and the mixing incorporation of the molasses. That goes very quick too. I mean, I would say within an hour and a half, two hours...
Anna (41:01):
Yeah, when we set up research trials, it only takes us about half a day. Actually it's easier to set up ASD treatment on an entire high tunnel compared to like [inaudible 00:41:14] trial. One thing in ASD, if you're setting up ASD and you also form the beds for next season, because that's, that's one nice way to do ASD is you'll apply the carbon sources, you'll form your beds, lay your drip tape, lay the plastic. The nice thing is, you know what? You don't have to do that next season. You're saving yourself some time in the future.
Ben (41:36):
Yeah. I was thinking about that. You got to cover the soil, you can either saturate it and then cover it or you can cover it and then saturate it. If you're already going to be putting a crop that is going to use plastic mulch in there, to me, it seems like the perfect it's almost seamless. It makes, it makes this process. I mean, it has to be a part of the process for it to work, but it's also a thing you have to do anyway.
Anna (42:02):
Exactly.
Ben (42:02):
It just, to me, it seems kind of beautiful.
Anna (42:09):
Bob and Jenny's production system, they plant flat and flat beds on the ground, but most of our growers are doing raised beds. Especially, if you have a bed former, you till you take your bed former through. That bed former has a plastic and a drip tape layer, you're done in about two hours. It's wonderful. That's again, why when we set up these research trials, we're forming beds by hand. It's a lot of physical labor for us, but if you've got mechanization and even Amish with horse drawn bed layers, they can get these trial or get this treatment set up relatively quickly in their tunnel. I'm saying half a day and what Bob said, a lot of that pretreatment you have to do for the tunnel is ripping out plants, baseline tillage. That can take a little while, but it's not too bad. Total time input probably a day. If you can budget for a day of work, you'll probably have no problem fitting ASD into your schedule.
Ben (43:10):
Okay. Okay.
Anna (43:11):
The other nice thing, if it's raining and you can do it in a high tunnel, even when [inaudible 00:43:16].
Ben (43:16):
Hey, that's a smart thinking.
Anna (43:18):
It's a good rainy day project.
Ben (43:19):
Yeah.
Anna (43:20):
Just don't leave your wheat meads out in the rain.
Ben (43:24):
That's really, that's a really smart use of a rainy day. Yeah.
Bob (43:27):
Now the other component, if I can just add kind of a point on the final point on that would be as far as, I mean, it seems like waiting for us is the biggest component. The actual physical labor is fairly short duration, but then it's the irrigation and the waiting. You have to remember that after you've done that physical labor, then you've got that flood or overhead irrigation where you're driving that soil to the anaerobic state. Depending on your system for us on a flat ground, in our high tunnel, probably this past season, I would say we probably irrigated for at most three hours.
Ben (44:13):
Is that right? To get to the initial anaerobic like you're at saturation?
Bob (44:19):
Exactly.
Ben (44:19):
About three hours to reach that, but was there maintenance irrigation that you needed to keep it that way for the duration of that time?
Bob (44:27):
Basically, how we've generally done it was the end of the day after we did our incorporation. We ran our overhead irrigation for about an hour and a half then, because you're already late in the day we come back first thing in the morning, kick the water on again. Run it for about another hour and a half and then immediately cover.
Ben (44:52):
That was overhead open that's for overhead field type thing. Yeah.
Bob (44:56):
Okay. I've not, I've not had the experience with the plastic culture any kind of... Using drip tape or whatnot. I can't weigh in on that but...
Ben (45:08):
I have a feeling it would take a little longer, I'd have to think about how long it would actually take. If you're on beds too, I can't help but wonder if it would drain and you might have to do some maintenance.
Anna (45:19):
Yeah. Except Bob brought up what I suggest. Again, you want that saturation to go to the depth that you incorporated the carbon source. Six to eight inches deep, if you can get 12 inches deep. The nice thing is usually you can just take a shovel and pull it, put it in the soil and pull it back and see how saturated your soil is. What Bob had mentioned is do that initial flooding, let that water settle and then come back and do a shorter flooding. It's very soil texture dependent. It's dependent on the compaction of your soil. When I talk to growers, my recommendation is make sure those soils are saturated to a depth of six to eight inches.
Anna (46:01):
We don't see, we haven't seen the need for maintenance irrigation during the treatment because what's really important is you're going to have enough water with those, maybe that first initial flood. Then the next day, adding a little more. Those soils are going to go anaerobic with that amount of water and they'll stay moist enough. We've run quite a few trials across the state on a lot of different soils. Even on a really sandy soil, those soils were still pretty wet when we uncovered them four weeks there.
Ben (46:35):
Okay. Oh, that's great to hear. Okay. It really is. It sounds like it's a set it and forget it kind of thing almost.
Anna (46:45):
Yeah.
Ben (46:45):
Once you have it saturated, you get the carbon source incorporated, the covers on it's just waiting and there's really not much else to do.
Anna (46:53):
You might not forget it because ASD, if it becomes more effective, it smells terrible.
Ben (47:00):
We've gotten to this piece. Okay. How bad is it? Is it a problem like with neighbors? Or... Tell me about it.
Anna (47:09):
Not that bad, especially because one thing, if you're smelling it, especially you should have your high tunnel closed up pretty well. Hopefully you don't have a very leaky high tunnel, and hopefully if you've done a good job covering and sealing your soils, most of those gases are going to be trapped. Again, you want those gases trapped because that's what's killing the pathogens. For example, in Bob's high tunnel, they have it sealed up nice and tight, but you can pop your head in and know that it smells pretty bad. What it smells like, I grew up in Minnesota the land of 10,000 lakes. When lakes go anaerobic in the soil, they smell pretty nasty. It's worse than that. I like to say it smells like the rear end of a cow. It's pretty odiferous.
Ben (47:58):
Yeah. I've dug into some horse manure piles of my neighbor to make my own compost and stuff, but he doesn't turn it right. It's just making a big pile. Yeah, in the middle of that, it's pretty ripe. It's pretty ripe.
Anna (48:12):
Yeah. It's pretty ripe. From a research standpoint, when we talk about these different carbon sources we use, if you use a different carbon source at the end of ASD, you have very different scents. With wheat meads or wheat bran, it's a pretty stinky final product that you'll have. Now, this also brings to a good point. It smells terrible. Those are some residual byproducts of ASD. Before you plant into those soils, you want to give those soils some time to air out. If you're planting in beds, you want to make your planting holes, let those soils sit for five to seven days.
Ben (48:50):
Okay.
Anna (48:51):
You can flush them a little bit with fresh water or fresh irrigation water, and that can help speed up the process, but you don't want to go right into those stinky soils.
Ben (49:01):
Okay. That's good to know. That's really good to know. Is there any residual fertility effects on this?
Anna (49:09):
Yeah, so there are. A lot of our Amish growers have seen like a nice boost in plant vigor due to some added nutrients from your carbon sources. That's one thing that we haven't quantified really well with my research, but we do have a new collaboration with researchers at Penn State and Virginia tech. Part of that project we're looking at, coming up with fertility recommendations for growers in the Midwest, Northeast and Southern United States for vegetable production. Particularly in high tunnels, if they're using ASD process. Because we know there's a need and hopefully, so give us a couple years, and then we'll have a better answer for you.
Ben (49:53):
I mean, honestly, even without ASD, it could be useful to have a guide. There isn't a lot available and there's some basic lessons, I guess, that people have shared and that you don't need as much fertility anyway, in a hoop house situation. It's not exact, I haven't seen like different recommendations in extension publications too much. It'd be useful, whether it's ASD or not. Just hoop house fertility, it'd be really good.
Anna (50:26):
Yeah. It's definitely a need in our study network, we're starting first field trials will go in spring and we're looking at a couple different carbon sources. Again, we're looking at wheat meads, soybean mill, distiller dried greens. Each of these differ in how much nitrogen they have and other micronutrients and macro nutrients.
Ben (50:47):
Yeah.
Anna (50:47):
Hopefully we'll come up with good recommendations for different carbon sources.
Ben (50:54):
Okay.
Bob (50:55):
Kind of an additional benefit I would say too, is that we haven't talked about is kind of your soil texture, the tilt of the soil.
Ben (51:03):
Oh, really?
Bob (51:03):
I think it's definitely improved as well. It's kind of like adding an additional like a compost, like a leaf mold or whatever because the texture of the soil is really nice when you go back into that bed or that flat ground after the treatment's over, you're ready with your soil.
Anna (51:24):
That's probably one of the most noticeable things that most of our growers have commented on when we do trials on their farms, is that they've noticed the soil is a lot more workable and I haven't done any direct measures, but like my current explanation is you have, wheat mead is a pretty fluffy byproduct. You work it into the soil and then the microbes pretty much destroy it completely. You have all these nice kind of fluffy packets that are left in the soil. That helps with the workability of the soil.
Ben (51:57):
That sounds like a neat benefit. That's not something that was on my radar from learning about this process at all.
Anna (52:04):
It's not something we thought of either, but it's something we've heard repeatedly from growers.
Ben (52:11):
Okay. All right. Well, we're getting close to the end here. I don't want to take too much more of your time, but there was one other topic I wanted to just touch on and that is in relation to growers growing in hoop houses, particularly tomatoes for year, after year, after year style production. What you had mentioned before about three years is when they start to see effects of build up of some of these production limiters. Once you get to eight years, 10 years, your plants just don't even make it through July sometimes. That is what I saw here in my part of Michigan with some growers.
Ben (52:51):
What they chose to do, I don't know if they knew much about ASD at the time or not, but what they chose to do was graft. They saw immediate overnight, like one season difference. Like just complete turnaround. That was very impressing to them. They've continued to do it. It sounds like both of these techniques would result in improved an improved situation. I can't help, but wonder if you just graphed and that's the only thing you did and you used the same rootstock every time. Eight years later, are you going to run into the same problem?
Anna (53:29):
Potentially because unfortunately those rootstocks aren't resistant to all the diseases we're finding and probably the key disease that rootstock wouldn't protect you from would be root-knot nematode.
Ben (53:40):
I see, because I saw in your paper, the Northern one is the one that isn't affected.
Anna (53:45):
Exactly.
Ben (53:45):
That's the one that's the problem around here.
Anna (53:46):
Exactly. Unfortunately, the dominant, we found root-knot nematodes in about 50% of the high tunnels we surveyed, which is terrifying to me as a plant pathologist but rootstocks, well, some of them will have root-knot resistance. That resistance is only to the Southern root nematode or meloidogyne incognita. Meloidogyne haplo, which is our dominant root-knot nematode in these high tunnels and temperate regions, there's no resistance in these rootstocks. The other thing colletotrichum gloeosporioides, there's also no resistance in those rootstocks. That's more of a minor disease, but you know, we still don't understand. Maybe with root-knot nematode, colletotrichum gloeosporioides could be more of an issue, but you're not going to have [inaudible 00:54:33].
Ben (54:33):
That's that's the corky root rot, right?
Anna (54:36):
Corky root rot is pyrenochaeta lycopersici. Colletotrichum gloeosporioides causes anthracnose and fruits.
Ben (54:43):
Oh, right.
Anna (54:43):
The reason why you should worry about colletotrichum gloeosporioides in your soils is that you have a ton of colletotrichum gloeosporioides in your soils, tou're going to really also increase your risk of anthracnose in your fruits.
Ben (54:54):
I see.
Anna (54:55):
That's going to also hurt your bottom line. Yeah.
Ben (54:59):
Okay. Yeah. Okay. I think that these deserve their deserve some chances to be mixed and maybe over the years we'll see growers adopting both simultaneously. Yeah. I like the idea of ASD though and that it doesn't require you doubling up all the plants, you need to then reduce them back to one, because that's what grafting is, right? I could see that being, I could see that being something that would be a huge factor in someone's decision making, if they knew both systems well, that could be a no brainer in terms of costs. If they've got a chance to see it more... That's often what it takes is getting to see it someplace, which I really enjoyed that you did that workshop. I can share this video with people now and say, "This is the thing I've been telling you about, you know the big long word anaerobic soil disinfestation, whatever it is."
Anna (55:55):
Unfortunately, anaerobic soil disinfestation is not a very good name. Yeah, from like a technical expertise standpoint ASD is definitely easier to apply than to adopt than grafting. You know, ASD I'm not going to lie about it. It's a physically labor intensive process. We said you can finish it with the setup and the application about a day. It's not too much of a time commitment, but it's laborious. It's not like you're going out in spraying. It's not that simple.
Ben (56:28):
Right. Cool. All right. Well, Bob, Anna, I appreciate the time that you were both able to spend with me today.
Anna (56:35):
All right. Thanks, Ben.
Ben (56:37):
Okay. See you.
Bob (56:37):
Thanks.
Anna (56:38):
Thanks, Bob.
Bob (56:39):
We'll see you. Thanks, Anna.
Anna (56:40):
Good. Bye.
Bob (56:41):
Bye-bye.
Ben (56:47):
Well, that's that one? What'd you think, Natalie?
Natalie (56:50):
Yeah, I just thought it was like exciting overall. I think when, when we talk about processes like bio fumigation, they can feel really overwhelming. It's just so much work and you have to get everything perfect. To see a process that is similar, but much more accessible and something that a grower could just do in a day and make a huge difference. Yeah. It was really exciting to learn about that and to have someone break it down, I think, especially because the name is so complicated.
Ben (57:19):
Yeah. Right.
Natalie (57:20):
It seemed like it must be really hard, and it's interesting. You say like, there is this kind of three-year period where things look great and then they start to go downhill. That's exactly what we're seeing in high tunnels in regards to salinity buildup. I don't know, that's just kind of an interesting mirror that both of these things kind of happen on the same time scale.
Ben (57:42):
That's a question after the interview was over, I had some lingering thoughts. One of the questions I sent to Anna after we were done was if she had noticed any effect on salinity, because in addition to the diseases, which is kind of the main reason that ASD has performed, there are two other really strong effects on a greenhouse over time and that is pH creep upwards. At least in our region, it seems like our calcareous bedrock results in well water that's alkaline. Over time, you get higher pH and it doesn't wash out from rainwater because you're covered. Then salinity as well also builds up from fertilizers, conventional and organic.
Ben (58:30):
They also do not really wash out because of the plastic being on all the time. I asked her in the process of ASD what happens to pH in salinity? What she was able to say about pH in her Ohio trials is that it's been sort of inconsistent, but more often what they see is no change in pH and sometimes a reduction. It doesn't bring pH down a whole lot, and it will have a lot to do with your water quality. I'm sure.
Natalie (58:58):
Exactly. Yeah.
Ben (58:58):
Yeah.
Natalie (58:59):
If you're doing it with alkaline water, it's not going to do it, but if you can acidify that water in the process.
Ben (59:04):
Yeah.
Natalie (59:05):
That would be an interesting combination of treatments.
Ben (59:07):
For sure. But then the salinity thing, she said, she didn't specifically look at that and she thought that'd be a good idea to look more into as a side effect of this sort of saturation process. But of course, same as with pH your water quality would have a lot to do with that.
Natalie (59:27):
Yeah. Interesting.
Ben (59:33):
That concludes this episode of the Vegetable Beet. If you'd like to check out all of our past episodes, head on over to glveg.net/listen. Sweet. Okay. Thanks, Natalie.
Natalie (59:48):
Okay.
Ben (59:49):
I got to run.
Natalie (59:49):
See you.
Ben (59:49):
Okay. See you.
Natalie (59:49):
All right. Bye-bye.
Ben (59:49):
Bye.

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vegbeet s03e01 (Completed 05/12/22)
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