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In this episode of the Nutrient Management Podcast, we discuss iron deficiency chlorosis (IDC) and soybean nutrient management. What are our guests working on for research on IDC? Is there anything new out there for farmers to help manage IDC? With the late planting and dry conditions following last year's harvest, are any impacts on IDC anticipated this year? What else should growers know about soybean nutrient management?
Welcome to University of Minnesota Extension's Nutrient Management Podcast. Each month we bring you the latest research in nutrient management for crops and how you can incorporate the latest tips and best management practices to your farm.
Nutrient Management Podcast episode: “Iron Deficiency Chlorosis (IDC) in soybean”
June 2022
University of Minnesota Extension
Written transcripts are generated using a combination of speech recognition software and human transcribers, and may contain errors. Please check the corresponding audio before referencing content in print.
(Music)
Paul McDivitt:
Welcome back to University of Minnesota Extension's Nutrient Management Podcast. I'm your host, Paul McDivitt, communications specialist here at U of M Extension. Today on the podcast we're talking about iron deficiency chlorosis, or IDC, and soybean nutrient management. We have three members of Extension's Nutrient Management Team. Can you each give us a quick introduction?
Dan Kaiser:
This is Daniel Kaiser, a Nutrient Management Specialist located out of St. Paul. My area of expertise is fertilizer guidelines. Some of which have involved looking at different management strategies for IDC in soybean across the Western part of Minnesota.
Seth Naeve:
And I'm Seth Naeve, I'm Extension Soybean Agronomist, and I am also based out of St. Paul, Minnesota. I have a similar appointment as Dan. I deal with everything related to soybean production, including some soybean quality related issues, but I'm... One of the things that we've always been interested in is this challenge we've got in Western Minnesota with IDC. So I'm pushing into this nutrient management area a little bit and working on some IDC related issues again this year.
Maykon Junior de Silva:
I am Maykon Junior de Silva, a second year master student in the Naeve lab, working with management strategies for iron deficiency sclerosis in soybean.
Paul McDivitt:
Great. So starting off, what are you currently working on for research on IDC?
Maykon Junior de Silva:
So, first of all, I would like to thank you, Paul, for the invitation to participate in this podcast regarding to talk a little bit about what we've been researching regarding iron deficiency sclerosis in soybean. So my master's project is title Managing IDC, or Iron Deficiency Sclerosis, with Agronomics and Economics. And I'll explain why. So IDC is a major management issue for soybean production in Minnesota because the regions where IDC prone soils are found overlap with the regions where soybean is mostly grown in this state and IDC is an important problem because most often its symptoms result in significant reductions. Therefore, due to the large impact of IDC on soybean productions, farmers have adopted several management practices or agronomics or agronomic practices or management strategies to mitigate your losses such as soil or [inaudible 00:02:20] applications of iron, tillage and drainage, planting companion crops, increasing seeding rates, planting tolerant varieties among others.
Maykon Junior de Silva:
However, because different management strategies can come at significant expense to soybean growers, the trade offs in cost and yield associated with their utilization may not maximize economic returns. Therefore, in order to overcome the problem and ensure profitability, practical and economical solutions are needed and this is what we are trying to do here. So we designed our study to evaluate three of the most often used management strategies for IDC and soybean, from a systems approach or from a practical point of view, which are variety selection. So we are testing two varieties, a moderately tolerant and a highly tolerant variety to seeding rates, 125 and 175,000 plants per acre, and three rates of iron chelates: zero, two, and four pounds of Soygreen per acre. And Soygreen is a commercial form of iron chelate.
Maykon Junior de Silva:
But you may ask, why these three management strategies specifically? Well first, because they all have been reported to be effective in controlling IDC by previous research. Second, because they are practical from a farmer's standpoint.
Maykon Junior de Silva:
So let's start with variety selection. So growing a tolerant variety has long been suggested or indicated as the most practical and most important strategy for IDC management. So in deciding which variety to grow, farmers can basically select a [inaudible 00:03:54] with high tolerance to IDC. Adjusting seeding rates can be effectively done by varying the plant density with a variable rate seeding equipment. In more application of an iron chelate as a liquid suspension at planting is also a practical option because many farmers, they possess planters equipped with such technology for similar applications on other crops or for the application of other products. Therefore, the first objective of our research is to evaluate the effectiveness of these three management strategies in individually and collectively.
Maykon Junior de Silva:
Secondly, we know that there is a trade off in cost and yield, relative to the adoption of each of these management strategies. For example, today's most tolerant IDC varieties. They come with some new penalty relative to susceptible varieties or relative to varieties grown elsewhere. Seeding rates, they significantly reduce IDC, but soybean seed has become increasingly expensive. Iron chelates, they have been a game changer for farmers in the most heavily affected areas, but they can be quite costly at effective rates. Therefore, our study also aims to evaluate the impact of variety selection, seeding rate, and iron chelate rates on return of investment or profitability. So overall, we don't want only to test this three management strategies, but we also want to be able to inform farmers which of them will offer the best economic return.
Maykon Junior de Silva:
So to accomplish the goals of our study in 2021, we planted our experiment at three locations in Western Minnesota on soils where IDC has extra historically exhibited mild to severe iron deficiencies so Foxhome, Graceville, and Danvers. This year in 2022, we planted only at two locations because we couldn't get to the third location. In addition to varying intensity of IDC, we planted our field plots in two different areas within each producer view: a hotspot area where IDC is severe, in a known hotspot area where there could be some IDC, but where IDC is not as severe as in the hotspot area. So our preliminary results suggest different management strategies to be recommended depending on the field location and the intensity of IDC symptoms, which is quite challenging when it comes to making a recommendation. More specifically, we cannot provide the same recommendation for a soybean field in Danvers and a soybean field in Foxhome, for example.
Maykon Junior de Silva:
Furthermore hotspot areas where IDC is severe, require more conservative approaches compared to known hotspot areas where IDC is less severe. In non hotspot areas, for example, our treatments showed less effect on soybean yield, meaning that farmers could even grow a less tolerant variety without the need of increasing seeding rate or applying an iron chelate. Differently in hotspot areas treatments varied in their effect on IDC. In a hotspot area in Danvers, for example, we found that increasing seeding rate of a highly tolerant variety to 175,000 plants per acre, significantly increased grain yield compared to the lower seating rate. However, the same effect was not found for Graceville, Minnesota. So managing IDC is very complicated overall.
Dan Kaiser:
One of the interesting things I know from some of the work, Seth and Maykon, that you've been looking at has been some of the linkage between soybean cyst nematode and IDC. Because one of the things that we were never able to completely nail down in some of the last work I did about five years ago, we had always looked for locations. We never really looked at cyst counts. And as I started looking into that more and more, we're having a lot of issues in areas with some of these management strategies getting them to work. And then I started looking at cyst counts and those tended to be high. And just one of the things, I don't know, if either of you two can comment on just kind of some of your work, if you've been looking at cyst nematode. Because I know when you start looking at some of the hotspots, right? You see the two can go hand-in-hand.
Seth Naeve:
Yeah. I'll chime in. This is Seth. This is a complicated issue. I had a student work on this project a few years ago and we had actually some really interesting findings. We probably could do a better job spreading those around, but it's quite an academic point. I guess the good part for farmers is that we don't see a real strong interaction for the symptomology. We were concerned that the IDC might flare up and cause more damage from the SCN or more yellowing and stunting and vice versa. That didn't seem to be the case. But what we did find that was really, really, really interesting to me was we found that the SCN continues to reproduce on even really highly stunted soybeans. So even soybeans that are just dead and yellow and ugly and yield 20 bushels or less still seem to support reproduction of this parasite, which is really surprising.
Seth Naeve:
When we think of parasite-host relationships, you don't think that... You think that the quality of that host is going to be an important factor related to reproduction of the... You would think that might have an impact on the SCN reproduction, but it doesn't seem to. So I think this might be in fact part of why we do see really high numbers of SCN in some of these higher pH areas with yellow soybeans. It may be partly due to the fact that we've had good reproduction, even in those areas with poor yielding soybeans. And so it's something I think we need to maybe think about how we manage this long term. I don't know exactly what it does for our research standpoint, because I don't think we have to be as concerned about it from a research standpoint, the interactions. But from a soybean management standpoint, it probably is worth considering whether farmers want to continue to grow soybeans in areas where they know they're going to have very low yielding soybeans because of IDC, because they're still end up putting a lot of SCN back in the soil.
Seth Naeve:
So that's kind of a long winded answer, but that was our summary of that two, three year project we had.
Dan Kaiser:
I said, I just find it interesting when you look in a lot of the information we had, you look at particular in-furrow Soygreen was looking at some of the studies and we just couldn't... Look at what growers would show for the impact and just be pictures that'd be night and day. Dead or alive for some of these areas. And they just weren't seeing a lot of that. I think the last year, the study that I was doing strip trials at the time, and we had a tolerant and susceptible right next to each other and their two row strips that we started to see that more and more. And we started looking at sites that had lower cyst counts on it. And I was at least able to get some decent performance data, because that's the thing I've struggled with is getting good performance data, because the problem with IDC and I mean, and Seth and Maykon, I'm sure you've seen this too.
Dan Kaiser:
You can put it on an area where you think you have it, but you aren't necessarily going to know until that crop goes in. And I've seen it so many times where it seems like those areas move. And it's just the weirdest thing you mean, you look at it. I mean, you think, well, you've got to find out you talk to the grower. It should be right there where you get the iron chlorosis and you have maybe two replicates of your study inside of that area. And you got two without, and it makes it kind of hard to detect or look at some of your differences out there and get some meaningful information out of it. So that's the thing that's really driven me crazy about some of the studies. And I started going to strips a few years back when we started looking at it.
Dan Kaiser:
So we could then look at putting our treatments out over a longer area and wider, trying to condense our down verse fewer treatments to try to get some better data out of it. And that tended to work a little bit better for me, but it's one of those things. It's a challenge. I mean, it's a challenging problem because Seth was kind of mentioning the IDC and the SCN interaction there, but even the IDC, it's not anything I think that's completely well known in terms of why this problem is occurring. I mean, there's a bunch of theories from him and I think it's a single impact that's affecting it. So it's one of the things that you think you get it, the answer figured out, but like a lot of other things we look at with some soil fertility, there's still a lot we really need to learn about it moving forward.
Seth Naeve:
Well, yeah. And I think that highlights, some of Maykon's results with the variability in responses by location is that, and that is really the real question here is I think when the breeders looked at this. They came up with some really good varieties that were really IDC tolerant and then you put those out and everywhere that they were placed, they did better than the check. So yes, they seem to work everywhere, but I think if you really dove into it, I think if you really looked at the minutia, but there's different types of SCN or IDC. Sorry. IDC tolerants out there in some of these varieties and some of the varieties do yield a little bit better in under some of those conditions than others. And we're dealing with a lot of different soil chemistry going on relative to these soybean plants and the various varieties are dealing with it differently.
Seth Naeve:
And so that's why we're getting these different kinds of responses. And so it is really, really, really a huge challenge for us, I think all the way around. Back to your transect idea, I mean, clearly that's what's working for folks, the Bayer Company, they... Both of our locations this year are co-located with a Bayer plot where they plant single row plots as transects through fields so that they can see the variation through the field. And those aren't very quantitative because they're not collecting any yield they're just looking at greenness. But for this particular issue, yellowness correlates pretty well with yield. And so I think they can, you can, and farmers can actually go to these sites and get a pretty good handle on how some existing varieties and some new varieties look in some of these areas, and by putting a transect through the field, they're able to make sure that they at least have one area where they have some IDC because it does seem to move around a lot.
Dan Kaiser:
Yeah. And that's one of the things that growers... You have a lot of times want to look at some strip trails with and without, and that's the problem. And you get like a 30, 40, or 60 foot planter. I mean, you can't always replicate the same conditions across those areas. And I know I try to do some work. That's probably been 10 years ago with some growers and they just couldn't get the same results we could with some of the smaller strip trials. So, that's the main challenge with it is finding the area consistent enough. I mean, we don't necessarily see whole fields that go yellow. Although I know up in the valley, it can occur. It may be a little bit different in terms of what's happening up there. I know in Yellow Medicine County too, and some of the have been over there in some fields too, that will go completely or mostly yellow.
Dan Kaiser:
And otherwise you get these small pothole areas that are just yellow or on the rims. It isn't really the easiest to do work in some of those fields. So that's been kind of the main challenge. So. Seth and Maykon, one of the things I know that does come up is, we are doing testing and you're doing testing I've done in the past, looking at different varieties and looking at some of these different management scenarios, particularly the in-furrow chelates. One of the things I've seen consistently is that I get a larger yield response to my higher yielding, maybe my less tolerant variety, but then the maximum yield always tends to be less than I can get without the product with my tolerant variety. I don't know if you've been seeing some of the same things, because it always seems to me that the recommendation I'm usually giving to growers is starting with a tolerant variety. It may not necessarily get the return when it comes to some of the iron chelates that you would with the other one, but still it sets you up for a higher yield potential. It's kind of general... Generally what I've seen. But again, I don't know how some of these newer varieties, if they're getting better or not in terms of the maximum yield potential.
Seth Naeve:
Yeah. I'll take a start on that one, Maykon, then you can jump in. That's a challenge. Another challenge from a research standpoint is what varieties we use as indicators for that. And we can always choose bad enough varieties that look awful, that we can improve. For our particular study, we use basically two kind of a tolerant and a very tolerant variety. And so then we're looking at those because that's what we think that farmers should be planting. So the question is how much tolerance do you need to provide? But yes, I agree that we can always make those bad ones look better. So the question for us is really how much value do we get out of each of those pieces? And from a practical standpoint, my personal feeling is that we need to know how close we can get those.
Seth Naeve:
I think to your point is how close can you get those other varieties to the maximum yield by adding Soygreen? And because it's a lot easier for farmers with current technology to do a variable rate in furrow operation. Even if that variable rate is just flipping the on and off the switch or kicking the button as they go through the field than it is to do a variable variety of planting in a field. So we think that's a much more achievable goal is to either on and off with an iron chelate or else change rates of the iron chelate as they go across the field. So that's our angle that we're kind of hoping for with this. But if we find out that there's real heavy interactions, that in some areas you need to have both, then we're just going to have to deal with that. And talk about things a little bit differently, I guess. I don't know if you have anything to add, Maykon.
Maykon Junior de Silva:
Yeah. This is something we found in our preliminary results from last year is that sometimes only a tolerant variety might seem enough to control IDC in some areas, but then you move to other areas and then the tolerant variety itself is not enough and also suffers a lot from IDC. So that means you need a second management strategy, would it be increasing the seeding rate or applying Soygreen. Yeah, so it depends on the area, different results, very complicated.
Seth Naeve:
So one of the... I think we're... I'm certainly no soil scientist, soil chemist, but one of the confounding factors I think that are, and that certainly go together here, is this question about residual nitrate and water. And the way I look at IDC is a lot of this is mediated by water movement in that soil profile. And that's very complicated. It's moving. It's doing a lot more than just moving salts and other ions around in the soil. It's also creating anoxic and hypoxic areas in the soil. It's affecting rooting physically and the timing and movement of that relative to the timing of the soybean plant, I tend to... My personal gut feeling is that if there's one thing that we can look at as an indicator, a driver, is this water status in the soil.
Seth Naeve:
And I think it's going to be very... if we knew enough, it would still be very, very complicated, but it seems like that's what's really driving a lot of this. And typically when a normal planted soybean, typically this time of year we get some really hot weather, like we're going to have next week, this later this week. And we're thinking that maybe that'll help push these soybeans through some of this yellowness that we get out there. That's a lot of what we get in early July in a lot of years. So just don't know how much of that is increased plant growth and increased rooting, or whether that's actually pushing some of that water down deeper in the soil or else bringing more up through the plants and ripping through it in the soil, in the water, in the plant, excuse me.
Seth Naeve:
So anyway, a lot there, but it's part of my conundrum with this is this question about water and nitrogen. And I guess my whole point with that introduction... I guess that was an introduction... Was that in Maykon's study, we actually use extra and on the plants in half of the plots to actually create a little bit more of a hot... Of a variation in how much IDC we have. And he's even noted that we have a variation in how those soils respond to that extra N. So some soils that extra N really creates more IDC symptomology. In some areas it doesn't. So it's not going to be as simple as, as taking soil tests and determining whether we're going to have IDC. We're not able, I don't think to be able to do N rate tests out there for and determine thresholds for IDC. It's just very, very challenging.
Dan Kaiser:
Well, one of the things I've been hearing are getting more questions about them have been some granular forms. Traditionally, the majority of the ortho-ortho EDDHA products, which are the most effective products, have come in a dry form that you've had to turn into a liquid or in a liquid form that you can use directly. I think that's, Seth, kind of what you've been using is the Soygreen AST, which is the already mixed product. So that's been one that we've had some questions on. Anecdotally just listening to some of the information, some of the consultants, there seems to be some positives with the particular... Some of these products. The main thing, if you look at their use, they're still recommended for use as a band application near the seeds. So it's the same thing we're seeing or recommending with a liquid form, because one of the things about the EDDHA products, particularly the ortho-ortho EDDHA, which is the most effective form, is that it is mobile.
Dan Kaiser:
So it will move. So you want to have it near the seed as much as possible, and have it concentrated where those roots are in order to be able to take up. So a couple products out there for granular products, the Soygreen Granular 2.4. Wilbur-Ellis has a product out as well. The main thing on all these products, whether it's a liquid or a dry source, is you want to look at where the iron chelate is derived from. So just looking at the Soygreen Granular 2.4, it says derived from iron EDDHA, and then it gives a split to 85% of the chelated iron is ortho-ortho EDDHA and the other 15% is an isomer, or it's slightly different. It's an Ortho-Para EDDHA, which is less effective. That's really what's important when looking at a lot of these products is the percent of the chelated form of iron that's in that ortho-ortho form.
Dan Kaiser:
There are also some other questions about EDDHSA and some other different chelates. Really, if we look at where we have the most effectiveness it's been with the EDDHA. So depending on what product you have, there's different ones out there. So Soygreen isn't the sole source. The main thing is when you look at application rates, they're likely going to vary because a lot of that is because of the variation they have in that ortho-ortho EDDHA in the product. So that's kind of the main thing with many of these is to just look at these and just look at what the composition is. Some of them will say, I think, that the versatile from Wilbur-Ellis, I'm just looking at the label now. It says a hundred percent of the... Or that the drive from a iron EDDHA, but it doesn't give you the isomer breakdown.
Dan Kaiser:
So you don't really know with some of these in terms of the effectiveness of it. So that's kind of the main thing is when you look at these chelates, all these chelates, aren't... They're not all made identical. So that's one of the important things is just to kind of look at some of these and they may still be effective. It just may take a variation in the rate for them to work. So then that's kind of the new thing, because in the past, we didn't have any options for growers that didn't have liquid in-furrow, or maybe they were using a air seeder for fertilizer application. The interesting thing, though, I find with these products is if you look at... They still recommend in-furrow or some different placement methods that are still banned placements. So that may still limit a grower in terms of what they can do.
Dan Kaiser:
So this isn't a product you can go out and broadcast apply like you would a standard fertilizer and see the same results. It's still something that you have to look at going in and putting it and concentrating it near the seed. So that's been the main thing came up. I know some questions from consultants this spring. I haven't looked at it. It might be something really, we look at here in the future doing some tests on, because I really don't know much about it, other than it's pretty much the same source. It's just a little bit different carrier in terms of how they're applying it to the plan.
Seth Naeve:
Yeah, there's a lot there. I think, just to kind of summarize from a simple agronomist standpoint. I think you've got to look at that concentration of your product because there's a lot of generic versions out there. And so farmers are probably going to have to crank up their rates a little bit when they're using some of those products. And especially if they don't know exactly what the composition is. The other piece, I think that you brought up towards the end is something that we talked a lot about 10 and 15 years ago was this kind of population effect and linear distribution of the products and then the seed. And this pertains to both the seed and the furrow, as well as the iron is that those things, the soybeans tend to help themselves in that row combat this problem.
Seth Naeve:
And so the shorter, the inter-row spacing between those plants is the more value we get out of those is an iron deficiency chlorosis mechanism or a method to battle this thing. So that's why we originally recommended wider rows and higher seeding rates. And today, I think it's still our general recommendation that when we're planting in wider, or in very narrow rows, or with air seeders, that the population may not have as much benefit as we get with wide rows. But then with the iron chelates the same thing, Dan, is that when we're putting these things down in with an air seeder, they're getting pretty well dispersed. And that iron gets a long ways away from each in individual seed. So we just have to be I wouldn't say not to do it, but I think we have to definitely be a little bit more careful, especially as we move to an air seeder or some sort of really narrow row system.
Dan Kaiser:
Well, it's one of the things too, that I've had questions on rate wise, too. And with Soygreen specifically. You see the company talking about 2, 3, 4 pound rates with some of the liquid rates and from what I've seen with a lot of our strips, two pounds typically was sufficient. Maybe get some hotspots, you need higher rates, but the higher rates you might need with some of the other products too. So again, that's one of the things to watch out for is that the concentration of the EDDHA, the ortho-ortho isomer in particular, is important. So again, it's one of the things to pay attention to with these. Because you may be putting the same rate, maybe a material on two different products, but you might see vastly different results just because of the makeup of the products. It does make a big difference when it comes to IDC, just the amount of available iron there. You'll see it pretty quickly.
Seth Naeve:
It does it. This is a real tough thing to do research on. And farmers would have a really hard time quantifying a lot of these effects, but clearly it's something that farmers can play around with a little bit in their own farms, and they can vary rates as long as they flag those. We know that greenness really relates quite well to yield. And so farmers can get a pretty good handle on it. I know every year we've got farmers that have a plug nozzle in a row or something like that they don't get the product on or they skip for some other reason, or there's some other issue, or they change product middle of the day and they have a different greenness or yellowness on the side. So farmers should really try all that they can to best utilize those either accidental situations or develop a little plan to do some of that. And if they have to test a couple products, do it. Buy some two and a halfs, or a small quantity of another product and put it in there in strips along with it. And the good thing is they don't have to wait till harvest to know whether it worked or not. They can go out and pretty much take a look at yellowness and greenness out in the field.
Paul McDivitt:
Seth, I think you hit on this a little bit already, but with the late planting and dry conditions following last year's harvest, do you anticipate any impacts on the IDC this year?
Seth Naeve:
I'll start with the late planting piece of this. That's an interesting question. I guess I alluded to this earlier in the fact that it's hard to predict IDC. Soybeans do come out of IDC later in the season. So one would expect that planting later could really reduce. We know that too much water early on is stressful to the soybeans, but it's amazing late planted soybeans will give us pretty good IDC symptomology. In fact, in the old days, the breeders would identify locations to do all their research by just going out to farmer's fields that were yellow and they'd have the farmer till up an acre, and then they'd plant their studies in June or early July just to see. So it's very possible to get those symptomology even quite late. And so it's quite surprising.
Seth Naeve:
And then on the other side of this nitrogen standpoint, I think we can have a longer discussion about that. But it's... we definitely had more carryover and last year, and again, as I mentioned earlier, this... The N effect is probably quite unpredictable, but overall I would say more N definitely pushes us towards more IDC symptoms, for sure. Whether there's any kind of a threshold or minimum or maximum amounts, I think we could debate, but definitely there's no question that more N is definitely... And excess N is definitely part of the equation in most of the fields that we're looking at around the country.
Dan Kaiser:
Yeah, to me, it'd be interesting, Seth, to kind of look at whether or not there's a threshold out there for nitrate, because it's generally you put a high rate on or you have nothing in for a lot of the plots. But is there a tolerable point at which the soybean won't see a negative impact? I don't really know. I think there's been some work looking at different rates, but the hard part about this it's got to be as, as nitrate because generally the way that works is nitrates taken up and bicarbonate should be released as nitrates being taken up to kind of balance the charge. And bicarbonate's really the problem in the soils. And if you get wet saturated soils, it tends to build just because carbon dioxide forms bicarbonate and it tends to build and not release.
Dan Kaiser:
If you try to measure it's not stable, so you can't directly measure it. So it's kind of one of those things that it's kind of a hidden thing that it's probably there, it's probably impacting it, but you just don't know that overall effect. But looking at some of the data that we had last fall from two foot soil samples, it doesn't surprise me to see things being bad this year, just because it seemed like there's a lot of nitrate hanging around. We had a dry year and it didn't go anywhere. So it just one of those things to careful for, and there's not a lot you can do because the plant's going to take up nitrate if it's there. So I mean, trying to minimize it, at least over applications in the corn's probably the best you can do, but then you have a year like last year and there's the year effect is so much greater.
Dan Kaiser:
So, there's... we'll see kind of how things... As things progress here, you may see it yellow and go away. Murray may see it yellow and kind of stick around for a while. Only time really will tell. That's kind of the issue with it is once we see that occur, we... There's not a lot we can do. I know there's always some talk about going with foliar applications. And we know that the EDDHA, the ortho-ortho products, fully applied will penetrate the leaf and we'll green the plant up. The issue a lot of times is that you have to do this before the plant yellows. So once it yellows, it isn't necessarily anything you can bring it back from. So that's been kind of the challenge with rescue applications is are there any options? Because a lot of times it has to be done before the problem's going to be there. So it isn't the easiest thing to do. A lot of times you just, you stress to growers to try to set yourself up as best you can. And the tolerant variety is really the best you can do. And then having some of that upfront application is really kind of an extra layer of defense with some of these particular products. And then hopefully it won't go yellow. But said mother nature controls a lot of that. So it's not always that we can figure out when and where that's going to occur.
Paul McDivitt:
Anything else growers should know about soybean nutrient management?
Dan Kaiser:
We're working a few things. I think we updated a few things in the spring regarding the phosphorous guidelines. Nothing major. I'm still working on some projects looking at sulfur. I don't think there'll be any major changes out of any of that. And debating when we get done some of the changes with corn, with potassium guidelines whether or not we'll have some recommendations. So some things maybe to watch out for with that. I also am in the process of updating the IDC pub. I wanted to include some of the information that Seth has been working on with the nematode work. For the update we had back in, I think it was around 2012. That's kind of one of the things that hopefully this year we'll have that out to growers kind of look at some of the new information that's available to them just based on some of the current research.
Paul McDivitt:
All right. Any last words from the group?
Seth Naeve:
Well, I think the ultimate last word is, it depends on what the weather happens or what the weather does the rest of the summer. And that's the big question, right? So we thought it was going to quit raining and then here it keeps on raining for us. So from an IDCs perspective that certainly could continue to drive this thing and we could, could ride this for quite a while. On the other hand, we know that dry weather doesn't cure it either. So it really depends. But I guess from the big, big soybean perspective as a soybean agronomist, I'd say, "Remember it all happens in August and early September." So that's what really seems to define our yields. We have to have a decent plant out there at that time to take advantage of it. That's why we're trying to minimize IDC now is so that we have a nice big vigorous plant. We're probably going to have something out there, but we want to create as large of a plant as we can that time of year so that we can maximize good growing conditions towards the end of the year. And that's where we'll get the big yields.
Paul McDivitt:
All right. That about does it for this episode of the Nutrient Management Podcast. We'd like to thank the Agricultural Fertilizer Research and Education Council, AFRAC, for supporting the podcast. Thanks for listening.
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