Crop Talk by IAS – 07/01/26

As corn and soybean development accelerates across Iowa, fungicide season is quickly moving from planning to action. Recent rains, warm temperatures, and persistent humidity have created conditions that make disease scouting more important than ever. In this week's Crop Talk by IAS, our agronomy team shares boots-on-the-ground insights on crop staging, disease pressure, and what growers should watch as tasseling approaches.

In this episode, the team discusses:

• Corn growth staging and estimating days to tassel
• Disease pressure observations, including common rust and reports of tar spot
• Why scouting ahead of fungicide applications matters
• Fungicide timing considerations for corn and soybeans
• How weather and canopy moisture influence disease development
• One-pass vs two-pass fungicide strategies
• Weed control follow-up and post application evaluations in soybeans
• Using crop staging to improve application planning
• Soybean reproductive growth stages and fungicide timing at R3
• Practical reminders for staying proactive as crops rapidly advance

Conditions still matter field-by-field. As corn moves closer to tassel and soybeans enter reproductive stages, timely scouting and understanding crop stage will be key to making informed fungicide decisions in the weeks ahead.

Featured this week:
Nicholas Giesseman - Host and Eastern Region Agronomist 
Nick Thompson - Southwest Region Agronomist (Ellsworth) 
Owen Heetland – Northwest Region Agronomist (Cleves)
Erin Ricker- Eastern Region Agronomist (Masonville) 

🎧 Listen now
Have a question for the team? Send it to CropTalk@InnovativeAg.com

To learn more about Innovative Ag Services and our agronomy services, visit InnovativeAg.com/Agronomy.

Produced by IAS Communications in partnership with My Four Creative.

Transcript

Nicholas Giessman 0:00

Welcome to Crop Talk, brought to you by Innovative Ed Services, and this is our field scouting special. Each week from March through October, our agronomy team shares timely boots-on-the-ground updates from across the IAS geography. So you can make confident decisions as the seasons change. Today you'll hear a quick regional update from our IAS agronomist, including what we're seeing in the field right now, what to keep an eye on next, and a few practical scouting reminders you can put to work this week. But first, let's get it started with a little update from Nick Thompson on the west side.

SPEAKER_03 0:46

Thanks, Nicholas. This is Nick Thompson on the southwest side of IAS, covering anywhere from Ames up to Alden. We've had a good amount of rain here this past couple days and then this past week or so. Things are moving along now that the heat's kicking up. We're starting to see this corn really start to take off. And I've even seen one to maybe even two fields start to tassel around here. I think for the most part, we still have anywhere from four to five growing stages, depending on the field, before we hit tassel for majority of the acres around here. But things are moving along real nicely. As I've been out scouting, I've noticed some common rust start to pop up, which obviously as things heat up, that should slow this rust a little bit down. I've also seen some gray leaf spot and some northern corn leaf blight start to pop up. So it's just important that we uh get out there and we make sure that we know what diseases are in our fields currently, and it seems like it's gonna come a little bit sooner than we expected this year. So get out there and get looking at them early. I'd rather be earlier than later. Like I've said several times, this stuff works more as a preventative cure than it is a curative product. So if you get out there with little to no infection, uh that's where you're gonna be seeing the best result. I'll pass it up to the northwest now over to Owen and Cleves.

Owen Heetland 2:14

Thanks, Nick. This is Owen Heatland at the Cleves location covering Grundy, Butler, Franklin, and Harden counties. As we get to some extreme heat here, we'll really start to see the corn and beans take off. Was in a cornfield this morning that was roughly five leaves from tassel, and the bean field I'm sitting in currently is just getting ready to enter into the R2 stage. So we'll start to see stuff move pretty quickly here, but we will see a large range of things. I've seen beans that are barely into R1, into R2, like I said. And as Nick said, he's seen some corn starting to push tassels. I've also seen corn probably six to seven leaves, eight leaves away from tassel. The biggest things that I've seen this week are you know weed control. Obviously, we finished up spraying most of the uh herbicide on beans last week, but we are gonna do some respray this week. So to me, biggest thing is get out and look at your beans and see what you have for weed control. Since we did end up spraying a lot of Liberty and List in probably cooler and cloudier conditions than we would like, given uh what Mother Nature gave us, we did have some struggles in some areas. We did get some bigger weeds because of the rain and not being able to get in. So now would be a great time to look at those beans and see if there's any spots. Maybe it's just you know, endrows, waterways, etc., that need to be resprayed. But go ahead and get that taken care of. And then as we are significantly hotter and more humid, remember the rule of 150, and we may actually have to end up backing down that oil load a little bit so we don't burn the beans quite as bad. As far as corn, you know, really just scouting for disease and and stage. And as Nicholas stated at the beginning, we will talk here at the end a little bit about how we're gonna stage corn and beans and then how we determine, you know, how many days or how far off fungicide is. With that, I will kick it up to the northeast with Aaron.

SPEAKER_00 4:08

Thank you, Owen. I'm Aaron Record at the Masonville location. I cover Bikenan, Delaware, and parts of Fayette and Clayton County. Over the weekend, we got some more rain, but with the heat wave coming in this week, things are gonna dry up quick and the crops are really gonna start taking off. And with that, um, I know some guys are starting to think about fungicide season and it will be here before we know it. There have been a few reports of tar spot. Um, from everything I've been scouting, I haven't found anything yet. However, we have had the wet, humid weather with some of those heavy dews and fogs in the morning, which is the perfect condition for it. Um, so it's just a good reminder to be out scouting to see what disease pressure is out there, if any yet, and just starting to think about fungicide paths and making sure we get that application done in a timely manner. With that, I'm gonna pass it over to Nicholas and our Southeast region.

Nicholas Giessman 5:00

Thank you very much, Aaron, for that update. Kind of like everybody else said, we're corn's moving along, beans are moving along, we're wrapping up spraying. Uh Owen kind of touched on that of the rule 150. I know this week we're trying to get out there and finish all of our spraying up, you know, whether that be the second pass on beans or if we're out there doing some resprays or that last pass on some corn. Um, just making sure that we're adjusting our adjuvants to get the proper kill without having too much crop response out of that. And then looking at in diseasing corn and getting ready for that next step, you know, which is fungicide. We're not as far along as the west side. We're we're still seven to eight leaves away from tasseling. So we got a ways over here on the east side, but it's better to be proactive than reactive to planning. So still out there looking, trying to make plans when we're gonna get the helicopters in, we're gonna get the planes in, the drones, stuff like that. So getting ready to make those next plans down the road. Sounds like Owen was out in a field this morning and he said he was, you know, five leaves away from tassel. Owen, can you you know give us a little run through of how you're out there and you know saying, hey, how I'm five leaves? How are you how are you finding that?

Owen Heetland 6:09

So to me, the easiest thing is you walk out to a somewhat consistent part of the field and you basically just pop the top of the plant off and then start unrolling leaves. And so you'll start wherever the last leaf basically emerged. So as your leaf is you know horizontal, 30 degrees, whatever it is, it's fully out, you pull the rest of the leaves out and then unwrap. And each time you unwrap a leaf, you count it. So I basically had five leaves wrapped around that taffle. Now, without getting into the math, you know, it's based on degree days and how warm it is and humid it is, uh, will depend on how quick you're gonna push those leaves out. But given that the next week to two weeks looks extremely hot, I would guess that you're probably gonna look at three-ish days. But I would say probably in this weather, three days per leaf. So if that corn is five leaves away, that puts us at roughly 15 days until full tassel, probably 12 days until flag leaf. And then from there you can determine on you know when you think you'll be spraying, whether you use an airplane, a ground rig, spray at flag leaf, or what your plan is. Is that kind of what you figure, Nicholas or Nick?

Nicholas Giessman 7:23

That's the one that I use. I like that three. Now it can change, like Owen said with that growing degree days, and yeah, it's gonna be a little quicker than the in the next 10 days. You know, for sure it might be that three, but I always use that as a a rough guideline. It gives us a good spot to, you know, at least have an idea when we might think without doing the math every day and saying, hey, we actually pushed a little more this day or a little less. Using that three-day reference is I think gets us in the ballpark of where we need to be at.

SPEAKER_03 7:49

Yeah, I'm typically basing it off of that three-day reference. I'd say from the fields that I've looked at and just where what I'm gauging off of uh here in Ellsworth, I'm thinking that we're probably gonna be wanting to think about and definitely having those discussions late next week of should we be getting out there early next week and possibly doing fungicide with the way some of these things are moving along. Which I think I'm a little further along than you guys are with planting and crop stage, but uh no, we're definitely coming to that point where uh stage is gonna be very important to us and making sure that we're getting out there at the right time.

Nicholas Giessman 8:29

We kind of talked about staging. We know we're you know we're 12 to 15 days away from seeing these tassels. Optimum timing for fungicide, high disease pressure, low disease, any given year, what's your what's your optimum time to go? And then maybe, you know, with it being cooler and really you know having that moisture out there this year, what would be your optimum two pass time frame to you know get this application timing kind of lined up for the season?

Owen Heetland 8:53

I would say, you know, optimally, I always like to shoot for tassel. If you're doing one pass fungicide, the best time that research has shown, Iowa State has shown, companies have shown is always that tassel. Now there's lots of caveats to that. Do you have a machine? Can you spray a tassel? Do you have to spray before? Do you have to spray after, etc.? So I would say, you know, if you're gonna spray once, you're gonna do it with an airplane, it's probably better to turn it loose a little before than a little after. Now, if we're in a low disease environment, maybe that's a little different, but I would we haven't seen a lot of disease. I haven't seen it a lot of of disease, but I would expect with the warm weather and the amount of moisture and now the amount of time during the day that that canopy is gonna stay wet. I was just in a field and it's still got dew on it. At 80% humidity, it's gonna stay like that. That's great for disease, unfortunately. So I would say tassel is probably your time frame. Now, if you're doing a two-pass, which I know there's some of that out there, right now I would target tassel or just a hair before, and then roughly 21 days after that, whether that be brown circle or a little before that, if it was drier, maybe you'd push that a little bit later. But as of right now, that's kind of what I'm thinking.

Nicholas Giessman 10:09

With it staying wet in the canopy, and it seems to be the whole next week's gonna be about the same as it is today. So you're seeing a lot of hours of moisture in there. Do you think guys are gonna start pushing this the second pass or a two pass you know option this year seeing this moving forward? Or are you gonna have some at tassel time and then 21 days after tassel? Or what do you what are you thinking we're gonna run into?

Owen Heetland 10:33

I don't know that there's gonna be a ton of it widespread. I think there'll be more one pass and then scouting. I mean, there are guys that definitely planned on a on a two-pass in certain scenarios. I would say, you know, in late corn, higher yielding, uh, corn on corn, all those scenarios would be first you would look at a at a two pass. So I I think it really just depends on crop and area. I mean, I know as you get to, you know, eastern Iowa, specifically northeast Iowa, it's really hard to cover at one time because of the topography comparative to over here. So that's gonna affect things definitely too. What about you, Nick, down in that Ellsworth area? You get to some more, even more than here, big square fields. Did you have any guys talking about a two-pass down there?

SPEAKER_03 11:19

Yeah, so I've got a couple guys, you know, they've been considering several different things here. Just with the early disease pressure that we saw. I had a few guys even try and consider throwing some fungicide in their post, even, uh, which, as we've talked about on the last podcast, we you could see a payoff, you could not see a payoff sometimes. It's just tough to see with how small the plants are and the amount of coverage that you need. But a lot of two past discussions are going on right now with this area, a lot of those long rectangular 80s. There's a lot of low spots where the water likes to sit. And that's where I'm seeing the fields with those low spots and the in the spots that just have had water in them all year round. That's where I'm seeing the most pressure. Obviously, uh, it could be coming from the excess moisture of this year, the high humidities that we've had as of recent, but there's definitely some discussions on whether it'd be worth it for a two-pass. And I'd just say my rule of thumb usually is I'd rather run an early fungicide pass and then gauge it. It's something to consider. I like to think if we're gonna do a two-pass program, let's see how the first one works out first, and we'll keep checking up on it. If that second pass is needed, we'll get out there and we'll get that second pass done. With just the way that the application is here and um and the prices of everything, I think it's worth it for to make sure that that first pass is doing what you need it to do. Because we ran into an instance last year where we sprayed some fungicide and it didn't work on the southern rust as well as another fungicide that we had. So different fungicides hit lesions differently and hit diseases differently. So I think it's just when it comes to disease, it's one of those things where you just always have to be thinking about it. I don't think it's something that uh unlike weeds where we kind of know what to expect, we aren't a hundred percent sure what diseases you're gonna have. We have a very good guess. We have the maps that are showing us where the disease is popping up, but at the end of the day, um, you could have a map that says that there's no rust anywhere in Hamilton County, but then you go out and you look in your field and there's a little bit of rust in there. Disease, it really takes a lot of time and energy just scouting for it, in my opinion, and making sure that you're making the right decisions. Because just like killing the weeds, um, if you spray 2,4D on grass, it's not gonna do a whole lot. We hit the southern rust last year with a chemical that um does better on those smaller lesions, and we saw a better result out of that. So making sure you know what's out there and uh you know what you're gonna spray on is gonna be the most important.

Nicholas Giessman 14:18

Yeah, I would I would agree with that, Nick. So we kind of talked about corn, staging corn on that bean field you're in right now. You know, what stage is that? I think you kind of said it was getting close to going into R2, and then do you want to walk us through staging the beans and what you know, kind of go through that same thing? What's the optimum time to spray, you know, that fungicide pass on your beans?

Owen Heetland 14:38

Yeah, so this one uh I would pretty confidently say is in R2 now. Caveat that with their one seven being planted very, very early. So um this is about the only one I've seen in in R2. But basically, you know, to stage you're looking at flowers on the stem and location on the stem. So R1, I believe, is any flower, R2 is top foremost nodes of the plant, and so that continues to change as a plant grows and adds nodes. Um, you add another node to the top, maybe that means that you're back into R1. So um R1, R2 can last a while just like R3, R4 can, you know, they can move quick or last a while depending on how quick the plant is growing and and adding nodes. I say that to say basically your best time to spray beans is R3. Um it's been proven quite considerably through a lot of data that if you're gonna do fungicide, the best time is R3, which I would guess we're probably still two to three weeks away from. The beans usually get to R1 pretty pretty quickly. That's determined by day length. So usually June 21st or thereabout is when we start to get into R1, and then as the plant gro grows taller, um, that means that R1, R2, and to get into R3 will take a while. That is your best timing. The one challenge to that is if you're spraying for white mold. There are a couple white mold products out there they want you to spray at R1 because they are trying to protect the flowers from getting white mold on them. So if you're spraying for white mold, which isn't really a big thing over here, probably more in eastern Iowa where white mold is a little more prevalent, right now would be the timing to do that.

Nicholas Giessman 16:25

Not seeing so much right now, but I know that's you know, that's that's the do you push to go early with that product, or you try to find that optimum time? I think a lot of people split the difference, or depending on like over here, you're kind of at the mercy of the helicopter. When's that when's that helicopter come for most of these acres, or do you have a drone lined up to get there? So a lot of it on that end, you know, just application timing when when is your available applicator actually available and going to get there for you?

Owen Heetland 16:50

Yeah, I think that's a good point. Topography differences um over here, a lot more of that is done by uh by a ground rig. And so I'm sure we'll have a little bit of white mold spraying to go on probably this week. And then we'll probably be a couple weeks before we move into that R3 fungicide time.

Nicholas Giessman 17:13

That's all for this week's Crop Talk by AS. Thanks for tuning in. If any of our listeners have questions, feel free to email them to crop talk at innovativeag.com. Be sure to like, follow, and subscribe so you don't miss next week's update. And if you know a fellow grower who'd value a quick field snapshot, share this episode with them. For more agronomy resources and to connect with your local IAS team, visit Innovativeag.com and follow Innovative Ag Services on Facebook, Instagram, YouTube, and LinkedIn. We'll catch you next week on Crop Talk.