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Talking Crop is a row crop production podcast that brings current trends, actionable management considerations, and research updates from guest experts to farmers, agribusiness representatives, and agriculture agency professionals.
Hello, and welcome to the Talking Crop Podcast. My name is Kathryn Seebruck, and I'm a commercial agriculture educator with University of Illinois Extension serving Jo Daviess, Stephenson, and Winnebago Counties. Talking Crop is a row crop production podcast with episodes occurring every other week during the growing season between the months of May and September. In each episode, I bring on a guest speaker to discuss topics related to their areas of expertise. In today's episode, I talk with Dr. Harkirat Kaur, an assistant professor and extension specialist with the University of Wisconsin-Madison Department of Plant and Agroecosystem Sciences. Doctor Kaur and I have a wide ranging conversation in which we discuss the effects of wildfire smoke on corn, drought, fungicide applications, mycotoxins and silage, short corn and silage, and a few other topics in between. It was a very topical conversation that I think folks will get a lot out of. In the episode description, you'll find my contact information as well as Dr. Kaurs, in addition to links related to today's episode, including one to Dr. Kaur's blog, one for the fire smoke forecast website, one for the growing degree day calculator, and one to an open access article on the impacts of tar spot on silage corn. Dr. Kaur mentioned that this article is geared more towards producers, so it's more streamlined than typical articles, and it leaves out a lot of that heavy scientific jargon. On the next episode of Talking Crop, I'll be speaking with Dr. Marty Williams, who is an affiliate professor with the University of Illinois Department of Crop Sciences, and we'll be talking about his research on post emergence weed control and inconsistent weather.
Kathryn:That episode will air on Wednesday, July 9. Now onto this episode of Talking Crop, Corn Conversation, Wildfire smoke, drought, short corn, and more with Dr. Harkirat Kaur. Dr. Kaur, welcome to the Talking Crop Podcast.
Kathryn:Thank you so much for joining me today and taking the time to have a conversation. I'm very excited to talk to you about what you've been working on and some pretty topical topics, I guess you could say, that I think growers are interested in hearing about. So again, thank you for joining me, and welcome to the Talking Crop Podcast.
Harkirat:Thank you, Kathryn for having me. I'm really glad to be here and talking to you about corn and crops, two things that I really like working on.
Kathryn:Awesome. Great. I always get started right away just jumping right into the questions. Like I said, we're gonna be talking about a lot of very topical things. The first being wildfire smoke. We had this issue over the past couple of years, I and of course, this year. It's come back to haunt us. At the time of this recording, I was looking at the Canadian Fire Smoke Forecast website and over the next couple of days, which is what this website monitors. It predicts where wildfire smoke events will occur. And it's showing that Southern Wisconsin and Northern Illinois will be affected by wildfire smoke. What effects do wildfire smoke have on corn production? And is it all negative effects, or are there any positives to it at all?
Harkirat:I would like to start by saying that at the moment, we don't have any peer reviewed reputable research in our area to quantify these effects properly. However, the research that's been done in earlier and also the research that's been done in terms of understanding the light interception and everything is something that we go into to find answers for this question. For instance, when we talk about wildfire smoke, the first thing is that it creates like a haze. It creates like a cloud of smoke over in our skies, which kind of limits the amount of sunlight we receive. Since you were talking about tracking the Canadian wildfires, it's been expected that we will be receiving about 15% less light interception as opposed to, a normal year or historical averages. What that does is it definitely reduces the overall photosynthetic capacity in a plant like corn, especially because it is a C4 plant, and it has a higher light saturation point. It functions better when it gets more light, basically. That's one way to look at it. There is another, I would say, a silver lining or a positive aspect to it because we don't want to freak out at the moment and also trying to look where we can find those hanging parts. It's like when we have a layer of smoke in our skies, also what it does is it scatters the light better as opposed to in the absence of the smoke, so which would mean that now the lower parts of the corn canopy will also be getting higher amount of photons, basically. Now the plant can actually compensate for the loss of the photosynthesis in the upper canopy by being active in its lower part as well. At the moment, when a lot of corn is around, I would say, Southern Wisconsin or Northern Illinois is around V4 to V8, somewhere around that, this time is not very critical in terms of yield implications with respect to the affects of smoke or haze if we look at it from that angle. If the conditions persist and they go on until silking R1, R2 that's when it's a situation where we need to analyze that. Is it going to affect our yield in a substantial amount of manner?
Kathryn:It's really interesting how it has those negative effects, and I never would have realized that it has that positive affect of potentially, I guess, I should say not 100% sure, but that slight positive of of scattering light a little bit better within the canopy. That's interesting also that you say that there's not a lot of hard and fast research on these effects. Do you know of any research that's ongoing now that this has occurred a couple times? Is there any research ongoing to to look at this more in-depth?
Harkirat:Not that I'm aware of in the Midwest. People have been usually focused more on wildfire research, I would say, around the West Coast. But now since we have been having these situations coming at us over and over again in the last decade, I think and and a lot of researchers around the land grant universities in the Midwest have been trying to put together these under like, knowledge pieces to answer questions. I assume there would be some that would stem from this sort of collaboration. But, unfortunately, at this point, there is not at least I'm not aware of.
Harkirat:Won't say there is no one doing it. There might be somebody doing it.
Kathryn:Like you said, it's been happening a couple times now or a few times, I should say, over the past few years, it would be definitely interesting to see what researchers come up with. Something that's somewhat related to this is that there has been, this year, a relatively lower accumulation of growing degree days thus far in this season. I wondered if slower crop growth is a direct effect of that. Are there any other secondary effects of this lower accumulation of growing degree days thus far in the season that growers should be concerned about or at least cognizant of? Not many deteriorating effects at this point, I would say. But, if this continues, it's going to eventually show up in our grain filling period and also eventually in the dry down. We might have a wetter crop as opposed to the moisture that we target when we're harvesting corn. Those kind of things. But at this point, the only situation that the growers are looking at is a slower growth for their crops. A lot of who I've been talking to some of them and the ones who have already planted their corn, say, early May or late April, which is quite early for Wisconsin situations. Even their corn is not progressed to V10 or V11. They're still around V7, V8. It's it's been slower and on the lower side as opposed to the overall average, I would say. This lower accumulation might be more of a concern later on in the season during those more critical periods. Right? But is there any from your understanding, is there any need to be concerned about potentially increased vulnerability to stressors due to that slower growth?
Harkirat:I would say, number one, especially for the silage growers, maybe it could affect the overall height of the plant. It's like and that kind that kind of goes into the affecting the overall plant biomass. Is now we are harvesting the whole plant. If your plant's not a sufficient height or a targeted height as needed, it will obviously show up as as a decline in the overall yield component that you are looking at.
Kathryn:Moving on to another topical concept which is, of course, drought. You don't want to yell drought too loud, right? Similar to where we're getting the wildfire smokes also in this area in Southern Wisconsin and Northern Illinois, we are also experiencing a bit of drought conditions and we have had some locally replenishing rainfalls throughout the area. Just enough to get the crop by but the drought conditions are continuing to persist a bit in this area.
Kathryn:Thankfully, I think today, we're going to be receiving some more rainfall which is great but obviously, we don't really know what's going to happen in the near future and the rest of the growing season. We can't control the weather. We can't control rainfall. So, what can producers do to maybe buffer their crop against the effects of drought conditions?
Harkirat:I would say, and I assume most of them have already taken a step in that right direction, is to have the timely nitrogen applications in the field in order to ensure that the plants are surviving the stress or the low moisture stress that they are having at this point. Most of our region, like Southern Wisconsin, Northern Illinois, growers have been focused on using drought resistant traits in their hybrids, which actually eventually help their crop to get by through the lower areas of stress. If dry conditions continue later on and for example, last year, we observed southern corn rust in this in South of Wisconsin, which I talked to some of the senior faculty and senior researchers, and they were like, this is one of the very few incidences when they have seen southern rust show up in corn, and that was primarily because the time between, I would say, late June to mid August and everything. That was really dry. That affects the overall plant health and its susceptibility to these kind of fungal infections as well. Last year, we did start with a very wet spring, which is not the case this year. Although we have our crop in the ground, one, it's a little delayed because of a lower GDD accumulation, which further puts the plant on the stress. I would say the solution at this point is not a silver bullet, obviously, but keeping an eye on our nitrogen requirements. I know irrigation is a costly solution, but in case the crops are really stressed, I would say, we can look into that as well. Timely nitrogen application is one of the few things that we can do at this point.
Kathryn:Looking ahead it's crazy to think that we're this far in the growing season already and before we know it, we'll be coming up on those critical timings for fungicide and insecticide applications and of course, with the dry weather, it's hard to consider that we potentially could have disease issues. But like I said, we never know what's gonna happen with the weather. Something I harp on about on the podcast and elsewhere in my job is that scouting is paramount to a lot of ways to be successful as a producer. To be more specific though, what is your recommended scouting schedule and strategy? When should folks start scouting?
Kathryn:How often should they scout, and what should they be doing when they're scouting? What's the best way to do it? I think some folks might just think go out in the field, walk around a little bit. But is there more of a a strategy to it that you can talk about?
Harkirat:I would say when I'm out there in a grower field scouting, I would generally like to cover at least one tenth of the field area to have an overall picture of what's going on. And that might mean that entering the field through different parts and trying to go into the depth of it as much as possible. Overall I don't think it's set in a stone rule, but I would say covering one tenth of the total field area is something that gives you an overall great picture of what's happening in your field and what are the steps you need to take in order to ensure that your crop survives. At this point, if it was last year, I would say go into the fields right now and look for any slug damage. But this year, since we're already short on moisture, I don't really expect that to happen, but I would still say be be cognizant of any holes or streaks that you see on the leaf that might be a slug infested field, which would eventually result in weak plants and make it susceptible to other kind of diseases. Going forward, I'm a big advocate of going in to scout for egg mass scouting, especially for certain kind of Lepidoptera insects, say European corn borer or western bean cutworm because those are the precursors which eventually would result in maybe ear injury and aid fungal infections as well. Around V12, V11 is when you should probably go into the field and look into the upper canopy to see if there are any egg masses. Because if there are, that means maybe you need to decide on having an additional insecticide application as opposed to just a fungicide. For the diseases, I in our environment, things are really unpredictable. As you said, we can't control the weather. I would just like to point out that in 2023, we started off really dry, but then we had this span of rainfall. From mid June to late July, it was raining quite a bit, which resulted in a higher accumulation of fungal infections such as ear rots, which resulted in other complications of mycotoxins and so forth. Scouting for ear rot around R1 or actually not R1, because you can't really see here also at that point. I would say because if you're looking for insect egg masses earlier in the season, that can actually help you get a picture of what's the weather looking like and what's the insect situation in your field looking like, and is there a possibility that those kind of things would interact? If they're interacting, that would put your field at a higher risk of those kind of infections, and that's when you decide to go in for a fungicide spray. I'm always an advocate of looking and scouting into the field before deciding on a fungicide because it takes time, it costs money, and those two things are precious.
Kathryn:Yes. Very much so. Related to that, when you're scouting for, let's say, disease specifically, and you don't see any signs or symptoms of disease, do you recommend that growers still make a fungicide application? I think that's something that some growers might struggle with making that decision on because it's like an insurance policy. But like you mentioned, it's an expensive insurance policy. It could be expensive because you didn't spray and then you end up with disease, or it could be expensive because you sprayed and there was really no need to. How do you help folks kind of balance that decision making process?
Harkirat:One thing I would say as a disclaimer, I'm not a pathologist. I refrain from advising growers on absolute decisions. Different sites because I look at it from the interaction point of view for the environment, for any external factors, and the inoculum present in the field. If you're not seeing any disease, but you're still looking at a weather which is very conducive to the diseases that are prevalent in your area or in your field history, it might make sense to actually invest in some fungicide. I would still encourage to hold off the spray as long as possible. For instance, if you are having a continuous cone rotation on your field and you have had incidents of ear rots earlier in the previous years and the environment is something which looks like a really nice cocktail for the fungus to grow, that's the time when we can actually act. And, yeah, just because now you have the history of inoculum in that field. It's like looking at the different factors, but I would still hold on to the application as much as possible. A pathologist might be able to provide you a better direct answer, but this is my analysis of the situation.
Kathryn:Sure. I think it's great to have that secondary perspective as well to get a a more a complete picture. In Wisconsin, which is a a dairy state. I'm in up in Northwest Illinois which isn't quite as dairy heavy, but we do have silage producers in our area. I was really excited to be able to talk to you about this particular topic today. In the name of fungal infections, of course, with silage production those two things are very important to keep track of, right? That's because of the potential of the development of mycotoxins. What diseases are of particular concern when it comes to mycotoxin production?
Harkirat:In our region, we mostly see accumulation of mycotoxins by Fusarium graminearum or Verticilloids. With these two pathogen the problem is sometimes when with the graminearum, it's like when you have very very moist and humid environment and temperatures around, say, 23 to 25 degrees Celsius, which would be around 72 to 75. That that kind of bracket, it would result in the production of vomitoxin or DON as we call it in the normal conversations. Those diseases, they affect our crop in terms of its overall quality and overall plant strength. Eventually, if the infections are a lot more, they would eventually also lead to yield implications as well.
Harkirat:The second part, because we are talking about silage, is that we cannot ignore the stalk because there could be stalk infections due to fungus as well. Fortunately, a lot of germplasm, a lot of hybrids we have been using in the area have a good resistance to stalk infections. We have not been seeing a lot of stalk rots and accumulation of mycotoxins due to stalk infections for over, I would say, last half decade. But it's something that always crosses your mind when you look at a plant as a whole.
Harkirat:The other part is the the chance of having fumonisin infections or fumonisin accumulation in the crop. That comes when you are having a little bit of a drier condition. Tt's like, damn if we do and damn if we don't. Like catch 22. Still the inoculum for fumonisin and fumonisin accumulation fungal infections are on the lower side as opposed to the gibberella or the graminearum where we have higher chances of it occurring. Fortunately, our region is safe or has not been under a lot of stress because of any aspergillus infections. We don't have a problem of aflatoxins, which is one of the major problems if we go towards the Southern States. A lot of researchers, especially in Iowa, have been trying to ensure that we don't have any kind of aflatoxin infections, but we haven't seen those as of yet. Coming back to your question, the major factors that we need to look at when we look at mycotoxin accumulation is if there are any ear rot infections, there is a greater chance that you will have a mycotoxin accumulation situation in your field. Sometimes it's like the inoculum is not too high to cause very high disease infections, but there is still a chance that there might be some accumulation happening, but that would be really minor and i it won't be as severe enough to make a difference in your crop. In a situation where you have an infested field and you have a field where you are seeing mycotoxins, the best way is to actually harvest it sooner than later. I understand we need to have certain moisture levels to ensure proper ensiling or packaging eventually. The longer the crop stays in the field, the higher the chances of accumulation and also the higher the quantity increases with time. Like, the mycotoxin concentration also increases with time eventually. Harvesting sooner than later is one of the strategies.
Harkirat:And second is feed dilutions. If there is no other option for you, but you need to use some of the silage that is from the field, which is affected with mycotoxins, you dilute it with healthy silage so that the overall concentration in the diet ration reduces and it alleviates the overall risk to the livestock eventually.
Kathryn:Can mycotoxin levels increase in storage too? Is there a period of time in which. if they're present, they can actually increase? Because living organisms are at play, Right? Can it increase over time, and is there a point at which it levels off?
Harkirat:The most critical time where it can actually increase is the time just before our silage enters into the anaerobic phase. There are different phases of ensiling. The first phase is where it still has some air in it. There is some oxygen availability in the silo and that's the critical stage where if there is fungus present in your chopped silage, it might result in further increase of mycotoxin levels. It's important to actually make sure that you take as much air out of the silage while packing it. It is a preventative strategy. Then the problem with mycotoxins is that they don't really degrade. If they're present preinsiling, they'll be present postinsiling. The only way of making sure that the level consistently remains slow is to ensure dry and adequately anaerobic packaging conditions where you don't have much airflow happening and which can further result in more infections in the storage time.
Kathryn:Okay, somewhat related to this that's more topical, and that is tar spot. It's already been identified in a few states or spotted in a few states, I should say. When it comes to silage corn, does tar spot have any particularly significant effects on corn silage?
Harkirat:When we talk about silage corn and tar spot, the first and foremost impact we see is the rapid drying down of the crop. The crop dries down real quick. There are two things to look at when we talk about this problem. Number one is that silage is usually harvested 45 to 50 days after silking. The tar spot doesn't really have as much time to affect the yield in silage, or we assume, or we hope that it doesn't have as much time to affect the yield as it has for a grain crop. It does affect the overall moisture quality of the silage, and it also impacts the overall digestibility in terms of fiber content and also starch accumulation because now you have a plant which is weak. Eventually the starch accumulation wouldn't be as effective. The overall digestible quotient of the plant decreases for the livestock. The silage is drier as opposed to what we expect or as opposed to the optimum levels, there are challenges while we are trying to package it in the silos later on because now it's harder to manage the airflow at that point. Those kind of situations there are quality concerns with that. There has been some work done in Michigan State specifically on silage, although it's not on a very large scale. Earlier at Michigan Stat, we were looking at those implications. We did see that there is a decline in overall digestibility and overall starch quality. We didn't see a very high decline in yield. That might also come from the fact that the fields or the site years we were looking into didn't have a very high severity of tar spot happening in those fields. In a year where we have tar spot I would say upwards of 25 to 30% severity, there are chances that we see a deeper decline in yield and in overall quality, specifically digestibility and starch.
Kathryn:Moving on, still on the topic of silage, but talking about, a newer technology that is on the wavelengths recently, and that is short corn. Short corn and silage, is that something that's being looked into recently?
Harkirat:Yeah. So so the thing is, like, with short corn, I would just like to reiterate it's it the plant is shorter than a traditional or conventional corn plant and it's, you know, about 25 to 40% smaller than what a traditional plant looks like. So there are questions across the grower community and also with the researchers that now when we're reducing the height, how would it translate into the overall biomass yield? Like, are we in the yield? And, like, what's happening in that case? Now we are trying to look at various venues in that. We're trying to look at what kind of population numbers that we need to maintain in the field in order to ensure that we do not take a hit on the yield. Also, when we are looking at short corn in terms of silage, we are looking at good quality numbers or I would say better quality numbers as opposed to. This is coming from our field research trials that we did last year, and we're repeating them this year as well. There are certain challenges when we look at harvest situations for short corn because now the ear height is closer to the ground. It's harder for the harvester to pick up everything. Those are the challenges that we are trying to look into. Also, you must be aware of the phasing out of BMR at this point. We are trying to see if there is a potential in short corn that could actually answer the quality related concerns that the growers have because now the BMR option is slowly being phased out by the industry. Those kind of option those kind of situations. Because short corn is shorter, it is more resistant to any situations of lodging due to storms or unexpected tornadoes that we get once in a while in our area or in our region. Those things are something we are looking at. We're also trying to understand how the changes in plant architecture would eventually affect the overall nitrogen management for those plants. There is a lot of promise.
Harkirat:There's a lot of questions. There is a lot of expectations both within the researcher community and within the grower community. I feel really fortunate to be at a position where I get to talk to both of them and collaborate with both of them to find answers to that. There's a lot to be seen and research and learn about this concept.
Kathryn:Yeah. I bet it's really exciting to be on the forefront of answering all those questions that are coming in from, like you said, both directions and both areas. Dr. Kaur, you are, of course, a corn agronomist. As a result you work on the hybrid performance trials, up in Wisconsin. I wanted to ask you, are there any newer technologies or advancements or even, I guess I should say, even older ones as well that you are particularly excited about or feel really strongly about growers either continuing to use or maybe switching to using in their hybrid programs?
Harkirat:With the drought resistant hybrids, when they came into picture, it was a big game changer for a lot of the growers. It helped them to manage their crops through stressed moisture conditions, and that's something that I feel like is a great investment when we are looking into hybrid selections and those kind of situations. And secondly, I would say at this point, considering what has been happening in our region for the last decade or so, investing into hybrid insect protection has been on the rise, and there are growers which are investing into VIB3 for Western bean cutworm or Cry1AB for European corn borer. They have paid off in the situations when they are trying to combat insect injury and has ensured that their crop is protected from any additional stresses that can be aided because of the insect injury. The third, which I would really like to see going forward is corn being resistant to tar spot. That is something I feel very passionately about and there's a lot of opportunity for collaboration between the plant breeding plant breeders and the agronomist where they are trying to come together to actually understand the G by E and management situation for tar spot. And I think going forward along with the fungicide applications that we are doing at this point, having tar spot resistance incorporated into corn hybrids is something that will be a game changer for the growers of our region.
Kathryn:Absolutely. Dr. Kaur, thank you again so much for joining me today for the Talking Crop Podcast. I was really excited to have you on being A newer faculty member up at UW Madison. It was really great to speak with you, and I'm very excited to hear all about the great research that you will continue to do and and push out going forward.
Harkirat:Sure. Thank you, Kathryn. I really enjoy talking to you, and I really enjoy talking corn. It's been a great experience. Thank you. With being a newer faculty, it comes with the all kind of excitements and challenges. It's because the core agronomy program has been a paramount program at UW Madison, and I feel really fortunate to be getting this opportunity to take it forward. Hopefully, we have good things coming.
Kathryn:Yes. Absolutely. That must be a really exciting position to be in. Again, thank you so much. I really appreciate it.
Harkirat:Thank you.