Mycotoxin problems are rising, but do you know where they’re really coming from and how to protect your herd? In Episode 45 of Ruminate This, Caroline Knoblock, Director of Nutrition at Agrarian Solutions, breaks down what dairy producers and nutritionists need to know about Fusarium molds, feed contamination, and practical ways to get ahead of mycotoxin challenges.
Caroline shares insights from a recent research trial on corn silage quality and vomitoxin (DON) levels, highlighting how fungicide applications at V5 and VT stages can impact both mycotoxin contamination and feed digestibility. She explains why many mycotoxin issues are out of your control, why early testing of freshly harvested feeds is critical, and how spreading spoiled feed can actually worsen contamination by inoculating soils.
You’ll also hear how healthy soils and smart hybrid selection help plants naturally resist mold infection and why DTX remains the most researched, trusted tool for broad-spectrum mycotoxin protection without binding essential nutrients.
If you’re looking for real-world tips to safeguard cow health and improve feed quality, this is a must-listen episode.
🎧 Listen now to set your herd up for lifelong success!
Scott Zehr
Hey, welcome everybody to another episode of Ruminate This with Agrarian Solutions. I am your host, Scott Zehr. And today I welcome in our Director of Nutrition, Ms. Caroline Knoblock. And we are going to be dissecting some of the results from our recent mycotoxin report. And I have a couple of questions I want to ask Caroline in regards to that report.
Caroline, so just give a brief overview if you would, let everybody know who you are, where you’re at in the world, and your role at Agrarian. I know this is your second time on our platform, but just remind people of what your role is.
Caroline Knoblock
I am director of Nutrition at Agrarian, so what that means is I’m doing technical support with Dr. Larry Roth. So I focus on the east side of the US, so I’m up in the Northeast and Pennsylvania a lot down through the Carolinas, which incidentally is also where we’re seeing a lot of the changes in mycotoxin exposure over the last two growing seasons. So it’s been fun to get into, and yeah, I’m supporting salespeople like yourself as well as our customers.
Scott Zehr
Nice tie in. I’m telling you what, you could be an old podcast pro at this. I mean, making a callback. I like it, to a previous episode, tying in. So, yeah. A few things, Caroline stood out to me about the mycotoxin report. One, they haven’t gone away.
Caroline Knoblock
Yeah.
Scott Zehr
Two, I, I feel like especially across the northeast, you get down into PA and even in some of the great Lake States, we’re maybe seeing a little less DON in years past? Is that, are you seeing the same thing as I am on that?
Caroline Knoblock
Oh, I think we’re probably seeing similar amounts of DON, it’s just the other mycotoxins are kind of increasing. So it’s kind of overshadowing the DON nowadays. But I think DON’s just been similar in these growing seasons and, I mean, part of that when you get into what is really happening with the molds and the mycotoxins is DON is just made as a part of the mold growing.
So part of just the normal metabolism of these molds is they make DON, it’s just a byproduct of them growing and expanding in the plant. So, we’re gonna see it. If the mold is there, you’re probably almost always gonna see DON. And that’s why we also call it that marker of…
Scott Zehr
Yeah.
Caroline Knoblock
…that mycotoxin marker. ‘Cause it’s just the molds make it. No matter what’s going on.
Scott Zehr
So then to play devil’s advocate, why do we sometimes see assays come through Dairyland Labs that do not have any DON detected on the sample, but we find zearalenone and fumonisin?
Caroline Knoblock
I had the same question. So I ask people that are much smarter than myself getting into these molds. And some really good agronomists with different states extensions. So one thing that they think is happening, so like I said, when the mold grows, it makes DON. When the mold is stressed, when it fears for its own life, that’s when it starts making the zearalenone and the fumonisins.
So there definitely are instances where you have a mold, but it’s not growing super well. It’s just not the right growing conditions for it. So it’s not getting bigger, it’s not inoculated more of the plant. So it’s not making much DON, ’cause it’s kind of staying static. But then that mold gets stressed, so it’s making the zearalenone or it’s making the fumonisin.
So you can have instances where you don’t see tons of DON. But that mold was there in small amounts, but it got freaked out, it got stressed. It started to worry about its own survival. So it made those two mycotoxins to kind of harm what’s trying to harm it. Is their defense mechanism, mycotoxins.
Scott Zehr
Yeah. Yeah. No, that, that makes total sense. Yeah, that makes total sense.
Caroline Knoblock
Not as common. But it does happen. So it’s, it’s normal.
Scott Zehr
Yeah. And you know, those are some of the questions that we get from nutritionists, right? So why I’m glad you’re able to answer that for us. You know, you’ve, you’ve referenced zearalenone and you’ve referenced fumonisin so let’s, let’s go that direction for a minute.
Zearalenone. So, you know, you’ve probably answered this question a little bit in your last response, but I wanna ask it this way. I mean, for myself, looking at assays for the last four or five years up here in the northeast, I, I consistently see zearalenone. Just, we always do. I think we have the right weather for it.
I’m telling you what, maybe I have a bad memory, but I’m, I, I feel like I’m used to seeing somewhere between 150 parts per billion and maybe two, 300 with a high sample being 500. And over the last, I’m gonna say eight to 10 months, we’re seeing some 1000 part per billion zearalenone. I’ve seen high-end samples at 4,000 parts per billion. Why do we think that is? Is it strictly weather related? Is that our theory?
Caroline Knoblock
Well, so that fusarium mold that’s making these mycotoxins, that’s growing super well in this weather. So, we’re seeing those growing conditions consistently. We’re seeing that mold just being in our soils, getting on our plants year after year.
So that’s why we have this consistent DON exposure, why you have this consistent, we consistently see the zearalenone. But yeah, like, you had said, I’ve, we’ve noticed those trends that zearalenone’s going up and up the last couple years. And that’s just when that mold’s getting stressed. So either it’s gonna be improper fungicide application.
‘Cause if you apply fungicide at the wrong points for if you’re applying it different points than what your agronomist is recommending, you’re probably, you could potentially be stressing out that fusarium mold. It’s a, “Holy crap. It’s not enough to kill me, but it’s enough for me to try to defend myself.” So it’s making zearalenone.
That’s why agronomists are super specific about when to apply fungicides. ‘Cause there are certain times in that just growth period of the plant, when the plant can defend itself from the mold. And then that fungicide just really helps it and get rid of that mold. But then you have those other times where it’s just not optimal.
So that’s why working with agronomists who are knowledgeable about molds and mycotoxins and following their advice is really important. ‘Cause the molds are there, our plants are getting inoculated with these molds.
And then, and it’s not just fungicides that stress them out and causes zearalenone. There’s just certain growing conditions that the mold doesn’t really like as much. Or there’s other pressures just in that plant’s immune system that caused this to happen. So it’s not super well defined, but it’s, we know that there are some things that might influence it.
Scott Zehr
Yeah, yeah, definitely. So, Caroline, you mentioned the fungicide applications. And I know we’ve, we’ve done some work with Ohio State, working with them on the assays of their fungicide research. They’ve put out some information and remind the audience, or I guess let the audience know, like, based on the work done there at Ohio State, when is the right time to apply that fungicide?
Caroline Knoblock
What what they’ve found over the last few years, somewhat consistently, is that when the proper fungicides are applied at full silking, that’s when you get the best results for reduced mycotoxins in your final feed. They’ve put out some really nice data when they applied fungicide to cohort fields at different stages of that plant’s life. And that’s just when you get the most consistent reduction.
People don’t really know why exactly. But, part of it is just that fusarium mold gets into the ears and it loves being in the ears and growing there. So, that’s probably has a lot to do with it. The fungicide just stopping that mold from getting in.
Scott Zehr
Yeah. And just so you know, folks, we will make that Ohio State data available to you in the show notes here of today’s episode. You also mentioned full silking. Correct me if I’m wrong. Folks, I’m no agronomist. My experience of growing corn was when I was on our dairy, our family dairy, and I would dish the fields and then I would fill the fertilizer hoppers for my dad who planted, and then I would run the chopper. I didn’t really spend a lot of time in corn fields, even though we grew corn. Full silking to me doesn’t sound like a very big window if I’m trying to cover thousands of acres.
Caroline Knoblock
Yeah, it’s a very small window. And that’s why you can see why it’s so, most people see inconsistent results from fungicide application. It’s that silking window to get it in in time before that mold gets in, very short. So if you’re doing a small number of fields, you might be able to target those molds.
Or if you have a lot of fields you’re doing and you know you have fields that consistently are very high in those DON or zearalenone, maybe those fields, you make sure you’re really tight in that window and targeting those fields where you know it’s really bad.
So, and that’s something again, work on with their agronomist, ’cause they, they know what they’re doing with this. They see it every year and they’ll be able to make sure it’s applied at the right time and really help target those high risk fields.
Scott Zehr
That’s a great point. You know, if I’m trying to cover a thousand or more acres, right? Find the fields that are maybe a, a problem child consistently. Which if you’re not sampling your corn coming out of the field, contact your Agrarian rep, myself. Email us [email protected] and we will help you get your assays taken this year during fall harvest.
Caroline Knoblock
Yeah, it’s very important to know what’s going in the bunk just so we can prepare, so that we are ready when it comes out.
Scott Zehr
Absolutely. And Dr. Roth talks about that a lot.
Caroline Knoblock
Mycotoxins are not going down.
Scott Zehr
Yeah.
Caroline Knoblock
No, they’re not going down.
Scott Zehr
So I’m glad you brought that up, Caroline, because I was on a dairy last week. And you know what, I’m gonna give the hot take right here on Ruminate This. I, that dairyman asked me if I was there to sell an inoculate. I said, no, we’re not in the inoculate space.
I explained to him you know, our DTX technology. And he said, “so this is a feed additive, not an inoculate.” “Correct. Feed additive goes in the cow.” He goes, “okay, because the last three salesmen that were here are selling inoculate and letting me know that they’re gonna be able to reduce mycotoxins with their inoculates. So.
Caroline Knoblock
I think it can be kind of a semantics issue.
Scott Zehr
I understand it could be semantics, but, you know what folks consider a PSA from, from me. If you have somebody coming at your doorstep selling you something to put on your bunk, because it’s gonna reduce the field-born mycotoxins, kick ’em outta the driveway, because Caroline’s exactly right. What we harvest from the field and put in our storage pile, bunk, egg bag, upright, doesn’t matter. It’s not gonna go down. And it has the potential to go up.
Caroline Knoblock
Yep.
Scott Zehr
And I think Caroline, you, you mentioned semantics and you know, was this inocular salesman talking to this farmer trying to be cute? Was he trying to be, you know, pushed a line? I have no idea. If we do a great job of fermentation and we’re getting oxygen out, right? We’re able to reduce the risk of increasing? Am I saying that right?
Caroline Knoblock
Yes. Yeah. It’s really, so the mycotoxins that go in aren’t going to go down ’cause the mycotoxins are extremely stable molecules. Heat doesn’t kill, heat doesn’t destroy ’em. The really only things that destroy mycotoxins are, rumen bacteria do a tiny little bit before mycotoxins kill them.
So they’re there. What’s really important is just the normal good feed recommendations. It’s reduced pack, pack, pack to get the oxygen out. You want that pH to go down quickly, because just preventing that mold from growing more and making more mycotoxins. So it’s mycotoxins can go up quite easily, especially in those that first 30 days after after putting it into the bunk.
Scott Zehr
But it’s not gonna go down.
Caroline Knoblock
No. No, it’s not gonna go down. Where people see…
Scott Zehr
It doesn’t matter if you’re putting buchneri on or if you’re putting a good lactic acid producing inoculate on, folks, it’s not gonna go down.
Caroline Knoblock
Yeah. And there is a misnomer that if you roasted your corn, your dry corn that your mycotoxins went down after, it’s not, it’s just that you blew off the chaff, the little, the chaff where mycotoxins tend to collect.
Scott Zehr
Yeah.
Caroline Knoblock
So if you have, I’ve seen people who have really a lot of mycotoxins in their corn, in their dry corn, they’ll roast it. ’cause then you get that blowing and it will go down slightly. It’s ’cause you’re getting the chaff off. It’s not a bad idea if you have to use that corn for your animals. But yeah, we’re not getting rid of, we’re not killing the mycotoxins. We’re just taking out that bit of the feed that is really high in it.
Scott Zehr
That’s a great point. That’s a great point. Well, Caroline, we went down that little proverbial rabbit hole, but I think it’s a good thing we did. You know, the, that’s a real life scenario that I just bumped into literally a week ago, yesterday actually. But, I wanna talk too about fumonisin. Now, Larry gave us the spring mycotoxin report a couple of weeks ago on Ruminate This. And you know, I guess my question is, where is all this fumonisin coming from?
Like why all of a sudden a mycotoxin that, yeah, it’s considered one of the big five. Man, if you look up some of the things that fumonisin can do, it, it doesn’t look pretty. But we really don’t, like, it was almost like an afterthought on an assay. For, for me, at least from the area that I cover and see assays from, for really the last number of years. And then all of a sudden, gosh, if you’re, if you’re in North Carolina, if you’re in Virginia, Maryland, Southern PA, we’re seeing fumonisin pop up in New York, but not at the levels, not at the levels we’re seeing in those other states I mentioned. Where, where do we think that’s coming from?
Caroline Knoblock
Well, bad thing is we don’t really know. So it’s from that fusarium mold. So it’s, that’s why we also tend to see DON and zearalenone in the same samples. But yeah, we don’t understand why there’s just so much more of the fumonisin mycotoxin than the others. And then than, and more than the past years. But yeah, those states, the Carolinas up through Southern PA, you’re, it’s that there’s that band in those Atlantic states that just have extremely high fumonisins in the feed. And it’s corn silage and dry corn. It’s not…
Scott Zehr
Yeah.
Caroline Knoblock
… either or. So we don’t really understand why, but those growing conditions last fall is just really ramped up.
Scott Zehr
Do, do you think it had something to do with the hurricane that came up through and, and really…
Caroline Knoblock
There is potentially…
Scott Zehr
…hit that very hard?
Caroline Knoblock
So, any kind of physical damage to the plant just creates a vector for that mold to get into the plant. And the more damage, the more spots for the mold to get in, it’s harder for the plant to fight off that mold. Because if you have super healthy plants that have minimal insect damage, wind damage, bird damage, you’re gonna have minimal molds, mold infiltration, and low mycotoxins.
But just that potential wind damage from the hurricane winds, and honestly molds, mold spores go through air, too. So there’s potential that that wind just helped push them up through that band. We’re not sure, ’cause it’s not typical for us to test mold spores in the wind, right around these times. So, that’s kind of speculation, but it’s, it is potentially related to that damage just to those plants.
And even if the plant was still able to grow and to make a good crop, it still experienced that period where it was fighting off a lot of things. It’s trying to recoup after that and then it has to fight off these molds.
Scott Zehr
Yeah. I mean it, you know, it’s almost like anything in agriculture, right? If it’s not one thing, it’s another. And I shouldn’t even laugh at that, but it is just really interesting how we’ve seen this rise in fumonisin which, like seemingly came out of left field.
Caroline Knoblock
Yep.
Scott Zehr
Really interesting. The other thing I would like to get your take on is, as Larry pointed out, we have a vast majority of samples with multiple mycotoxins. So bring us back to the cow for a minute, Caroline. These assays that we’re seeing come through, and it’s not by the fives or the tens, it’s by the hundreds of they have 2, 3, 4 different mycotoxins in ’em. How do we even approach controlling a mycotoxin sample that’s got four different mycotoxins in the corn silage or in the TMR?
Caroline Knoblock
Well, we need to be prepared going in. So that’s why Green Shop helps taking those green shop samples so we kind of have an understanding of what’s there. And then part of it too is, I mean, this is why we make DTX to have broad spectrum protection. Is ’cause we know this, these molds make many different mycotoxins.
So the way we grow our bacteria that we use in DTX, they’re growing on a mixture of all of these major mycotoxins. So it does have the ability to provide protection from these. But a lot of it is just working with us, with the nutritionist, with the farm to kind of pay attention to how is the cow responding to the feed?
How is she responding to this dose of DTX? Do we need to adjust it up or down? And we’re looking at repro, but that’s a longer term thing to kind of look at and it’s a back look. We can kind of also look at cell count. And a lot of these, especially in those Mid-Atlantic states with the fumonisin, they’re, people are having some success using bulk tank cell, somatic cell count as kind of the barometer of are we controlling this well enough?
There’s some farms where single dose of DTX is actually working pretty well. ‘Cause otherwise those cows are very well managed. Low stress on those cows. But if you have instances of just something else going on in the feed digestibility issues, or you have some overcrowding for a period of time, then those cows kind of aren’t as able to handle that mycotoxin load as well.
So we might have to adjust our rate up a little bit, one and a half dose or just depending on what’s there. So just balancing, testing our TMRs and then paying attention to kinda what the cows are telling us is what’s helping us control this?
But yeah, it’s never easy. And DTX is definitely doing its job because it has that broad spectrum protection, but it’s, yeah, it’s taken fine tuning in the really high areas. But it’s, we’re also learning a lot and we’re really learning how to consult well with our customers.
Scott Zehr
So I guess a follow up question on the multiple mycotoxin thing. So let’s say I get an assay back and you know, we’re maybe less than a PPM of DON, we’re maybe in that 100 PPB zearalenone range. And we’re picking up what’s considered low risk T2, and low risk fumonisin. Do we treat that?
Like if a dairyman or a nutritionist looked at that assay and everything’s in the quote unquote low risk, should that sample be treated like a true low risk sample if maybe I only found one mycotoxin that low risk? Is there a difference between finding one low risk mycotoxin versus four low risk mycotoxins?
Caroline Knoblock
Yes, for sure. We should definitely take it more as that aggregate amount of mycotoxin. So that’s, those diets where they’re all kind of falling in that medium to low risk, that’s probably a diet that’s getting into the high risk territory as the total TMR. Because each singular mycotoxin is okay.
But that TMR is getting into the high risk and, we have to remember too, with these mycotoxin, they all different mode of actions in the cow. They’ll do something different to cause inflammation, cause reproductive issues, cause immune stress and, and hurt digestion.
So, she’s trying to fight a lot of different things with this. And so yeah, those diets definitely give her a lot of extra things to take care of and… Adding, yeah, using DTX to support just broadly really helps her out. Prepares her to fight those mycotoxins.
Scott Zehr
I like the way you worded that too. ‘Cause it, it, like, we all, we all know this, right? That, that cow is, is fighting a battle on many fronts. Right? And maybe it’s environmentally, maybe it’s overcrowding or, you know, we don’t have great care on our stalls. Or, you know, maybe it’s she’s fighting a lameness battle or, digital dermatitis or, you know, just pick anything. Right? And then all of a sudden we introduce four different mycotoxins. That’s actually four different battles because they each attack that cow in a different way.
Caroline Knoblock
Yep.
Scott Zehr
That’s a great point, Caroline. Thanks for bringing that to light. Caroline, you know, I, I really appreciate you coming on here today and just bringing some of these insights of where these specific mycotoxins come from because it, to me, it really, it was really odd to see the rise in fumonisin, the rise in zearalenone and I think you’ve done a great job today of maybe bringing some of that stuff to light as the why behind it. Any final thoughts or insights you wanna leave with our audience today?
Caroline Knoblock
I think the biggest thing that I want to leave with just some ways we can kind of prevent these molds and mycotoxins is a healthy plant and healthy soil is just naturally able to prevent these mycotoxin causing molds from growing.
So whatever we can do to just have that strong, healthy plant. So with proper hybrid selection for your growing area. Good proper tillage practices. That plant will then be able to defend itself against those mold, mycotoxin causing molds. And if we have less fusarium, we tend to have less mycotoxins.
One other really big prevention matter is not spreading spoiled and visibly moldy feeds on fields. ‘Cause you were re inoculating your soil with those mycotoxin causing molds. So I understand that it’s hard to know what do I do with this feed? Composting is the best way, but, really stop putting it on your fields.
Do something with it other than that, and don’t feed it to your heifers or other animals either. It’s, it’s full of mold, it’s full of mycotoxin. You visibly see the mold, those molds that are growing are making more mycotoxins. So, it’s good to take it off your pile, try to compost it, dispose it in another manner, and not spread it.
Scott Zehr
I think that is probably the most valuable PSA we could have given the audience today, Caroline. I commend you for it. And oh, I, I agree, Caroline. I would implore our listeners to think of something else to do with that feed. And, you know, I’m, I’m kind of reminded, whatever you put into that animal is what you’re gonna get out.
And that’s my PC way of not using vulgar language on our podcast. So thank you for bringing that up, Caroline. That was great. Yeah, Caroline, you know, I, I do enjoy having you on Ruminate This, so anytime you wanna jump back in with us and spar with me a little bit, you’re always welcome.
Caroline Knoblock
Thank you very much.
Scott Zehr
All right, have a great day, Caroline. And we’ll be talking to everybody again in two weeks.
