Weed management recap & corn crop status prior to harvest
Well, good morning, and welcome to, the FieldNotes webinar. This is our last session, for 02/2025. Before we get started, just a couple of, housekeeping things that we normally talk about at this point in time. We're here to answer questions and have a discussion. Therefore, if you have some questions, you can use the q and a box, which is at the bottom of your screen to actually type in a question and click enter.
Speaker 1:There is also a chat button that we reserve for technical issues as well. If you just move your mouse near the bottom of the screen, you'll see the q and a box pop up, with that. When you log off today, we have a short three question survey that we'd like you to fill out, if possible, to give us some feedback not only on this seminar for today, but also your impressions of of past seminars. And we'll be also dealing with an opportunity for you to do a more comprehensive survey here, a little bit later at the end of season. Again, welcome to the strategic farming, field notes.
Speaker 1:This is a program from the University of Minnesota Extension. It's brought to you today by the University of Minnesota Extension and generous support from Minnesota farm families, through the Minnesota Soybean Research and Promotion Council, as well as the Minnesota Corn Research and Promotion, Council. We are happy to have you join us today. We're going to be talking about a review of the 2025, weed management's, season with regard to specific weeds and biology, and we also have an update and concerns about a status report of the Minnesota field corn crop and where we are, in 02/2025. To help us out on these subject matters, we welcome, doctor Tom Peters.
Speaker 1:Tom is a University of Minnesota and North Dakota State University weed specialist in the sugar beet area, but also works with weed biology in Minnesota and in North Dakota. And also doctor Jeff Coulter. Jeff is University of Minnesota extension specialist in corn, and we welcome both of those fine folks for discussion. With that, I'm gonna turn over and start with Tom here to begin with and talk a little bit about weeds. You know, Tom, this this last week, I was out at FarmFest, in Southwestern Minnesota down near the Redwood Falls area, And we had quite a few questions about weed control as you can well imagine.
Speaker 1:It's getting here towards the month of August. And farmers and other people are beginning to notice, different weeds such as waterhemp now poking up through sugar beet fields and soybean fields and so forth. Let's talk a little bit about weed biology and what we can imagine in terms of of of situations with that. A lot of comments about folks again about really, almost ornate in in awe about how a waterhemp plant and an infestation is able to keep, in a field situation all the way from early spring in through the month of August. Let's talk about that a little bit and maybe some other weeds in terms of weed biology and observations you made for 2025.
Speaker 2:Well, I I wanna start by saying that the observations from the growers at FarmsFest are are are very consistent with the same questions that I've been getting, Dave. Our producers, allied industry, all of our stakeholders have noticed that there seems to be more weed, weed escapes this year if you don't mind me saying that. And they're absolutely right. And I I guess what one of my goals for today is to talk through why maybe we had more escapes this year and maybe talk about how our plan will change or not change as we transition into 2026. So Dave, let's start a little bit with biology and let's focus on waterhemp first.
Speaker 2:So waterhemp is not the earliest emerging weed that we have. I would say common ragweed, giant ragweed and lambs quarters germinate and emerge first. We saw waterhemp emerge roughly the May 1 so the timing was typical. I think the real challenge this year with waterhemp is the consistency of the rains especially in June and July. So waterhemp germinates when we have a cooling cycle followed by a warming cycle.
Speaker 2:So that might be synonymous with a rain event. The rain event usually brings cooler temperature, cooler soils, rain adds moisture to the soil and cools the soil and then when the sun comes out and soils start to dry, that creates a flush of weeds and we've had some challenges with stand in some of the crops so these frequent rain events followed by openings in the canopy or failure to get row closure in some cases, it's just made a perfect storm I think this year for later season waterhemp germination and emergence. And you know, Dave, it's still germinating and I will bet 25¢ that these late germinating waterhemp are gonna make some seed yet this year. They're gonna flower and make seed yet before the end of the year.
Speaker 1:Well, I I think certainly that's the observations a lot of growers have had, and I think they marvel at the ability of waterhemp, with a small seed to continue to emerge, into the month of August as opposed to perhaps redwood pigweed and other types of weeds where you really you don't see that as as much. And so the question is, why waterhemp versus some of these other weeds not emerging, you know, later on in in the season? I don't know if we delve into too much genetics here, but in in situations and adaption, but the that's, you know, certainly one thing that people have have seen.
Speaker 2:Yeah. And and I will say this, though. We also have had some late germinating giant ragweed and common ragweed.
Speaker 1:True.
Speaker 2:So there's been a few calls about edges of the fields with giant ragweed that's come a lot later in the season than what we've expected and I got a picture this week of a newly germinated and emerging common ragweed. So it's a crazy year I think for weed germination and emergence and of course waterhemp's the worst. I'm sure we have other pigweeds as well that are still emerging But right now, waterhemp is is, the most prolific and important of our pigweed species.
Speaker 1:Well, people notice the adaption too of waterhemp and since it's, dioecious out there in male and a female, there's lots of variation that they've noticed as well.
Speaker 2:I I think, I think that's something that concerns me the most is every time it makes new seed from parents that could be maybe a half mile apart, we have the opportunity to make a plant that's unique and different than the previous plants and unfortunately we don't have a lot of herbicide options anymore. We've seen the onset of weed resistance especially with waterhemp so that scares me a lot. My mentor, Doctor. Allen Dexter at NDSU, University of Minnesota used to always say that dead weeds don't make seed and certainly they don't make new mutations of plants. So it reinforces the importance that we've got to really double down on weeds, especially waterhemp and do everything that we can taking an integrated approach to control waterhemp throughout the season, especially, later in the season.
Speaker 1:Well, let's talk about management for a little bit of time here. Tom and Natty, there's a lot of folks applying glufosinate under the trade name of Liberty. There's other herbicides as well. They typically will come to FarmFest and there will be a certain portion and I'll be, yep, happy things went well. Other portion, no, it didn't go well.
Speaker 1:I've had problems and sometimes you hear more of the negative than you hear the positive, but what are some of those concerns and so forth that you observed in terms of application, especially when we talk about post emergence herbicides?
Speaker 2:So let's just talk a little bit about post in general and I'm not gonna focus on glufosinate right away but we're making an application at one, two, maybe at the most three different points during the season. And again, what I told you earlier about the biology of waterhemp, germination and emergence is continuous. So the idea that we're going to make one or two well timed sprays and get waterhemp, it's just not going to work that way. So the starting point is pre emergence. We can't forget about pre emergence.
Speaker 2:What I like about pre emergence is it shortens the window instead of May through August, maybe our window is June 15 through August so it enables a better opportunity to maybe target weeds like waterhemp that are going through disgusted about what we've done or not done, let's not give up on PREs. We need pre emergence herbicides and let's continue to plan to use them in 2026. Now here's the thing about Liberty. Liberty performs best when we have humid conditions, when the sun is out and when it's warm. So those three things.
Speaker 2:And I will say this, based on my experiences, humidity is number one. I don't mind if it's cloudy, I don't even mind if it's a little cool out, but we need those humid conditions to get consistent waterhemp control and I think some of the challenges that we had is especially back in June, maybe even the July, we had some dry air masses and that contributed to some of the inconsistency. So even in my own experiments, Dave, I've had tremendous common ragweed control in July with Liberty, not so consistent waterhemp control from some June applications and I'm gonna go back but I'm gonna bet we can contribute the humidity as maybe an important factor that might help us to explain. Humidity, sun and warm temperatures, humidity being the most important of those variables.
Speaker 1:You know, also when I've, quizzed people a little bit more, it does come true that their memory of plant height, weed height is is variable and, you know, it's it's it's really important on a contact product like this in in waterhemp is places for regrowth, getting proper coverage, and keeping nine in there because, you know, I think you would agree, Tom, here, weed height plays into this because of the variability of waterhemp weed height.
Speaker 2:Yeah, so I think of weed height, I think of growing points. Water hemp has a tremendous number of growing points. So some of our producers are out there now with the weed zapper and I support that. I think it makes perfect sense especially to stop flowering. But the weed zapper probably isn't going to get the growing points that are deeper in the canopy and that's the thing with waterhemp.
Speaker 2:As it grows, we see more of these growing points and since Liberty is a contact herbicide, we need tremendous coverage. So nozzle selection, water volumes, droplet size, all of those contribute to overall waterhemp control.
Speaker 1:I believe in most cases that you've had better success at 20 gallons or enough water in that area, I think would be a good recommendation, Tom.
Speaker 2:Yeah. You know, it's funny. I always talk about water and I mentioned that to a producer. You gotta quit using 12 gallons. You gotta use 20 gallons of water, even 25 gallons.
Speaker 2:And there was a pause and he said, know, you're making a one day job into a two day job and you know, that's the way it's gonna be now with some of these weed control challenges if it takes more if it takes more operational equipment in order to get to 20 gallons, I think we're gonna have to figure that out because ultimately that's how we're gonna get control, Dave.
Speaker 1:Are there any other herbicides that of note that you might have heard of in terms of concern and maybe it's application, it could be other things related that we need to talk about beyond
Speaker 2:I think there's one. I wanna jump over to corn which will transition into Jeff as we, move into the second segment. But, some of the misotrione products have been the staple in broadleaf weed control in corn and some of the producers, some of our other stakeholders in allied industry have, mentioned inconsistencies with mesotrione products this year. So Callisto is the product name that people probably are familiar with or premixes like Sure Start and Triple Flex and they contain the active ingredient mesotrione which is a group 27 herbicide and I'm hearing some inconsistencies with overall control with those products, waterhemp again, and I'm sure that the various company, the organizations will dig into that deeper, but I just want to point that out only because some of the growers, producers on the call might be maybe wondering why my weed control in in corn wasn't as consistent as as it was in other years. So we're gonna be investigating that.
Speaker 1:Good. Tom, I got two quick questions that came in, from, listeners and viewers, this morning. One of them I think we've already touched on in terms of, how humidity benefits weed control and and there's speculation. Does it have an effect on the on the cuticle thickness or or thinner cuticle? And I I think we've, kinda talked about that a little bit.
Speaker 1:The other one is a grower indicating that in in his corn crop that both the pre and the post didn't work well. He has larger waterhemp population in his corn. He's wondering about a seed production for next year and thinking about whether to use a product like two four d, you know, with drop nozzles, high clearance sprayer to reduce the seed production. I guess what's your opinion? Now this comes up from time to time in in terms of physiological maturity of that weed seed, but, what about going back in there and trying to, not just salvage it for this year, but prevent seed production by going back in there and trying to drop nozzle something like that in corn.
Speaker 1:Is is that money well spent, I guess, at this point?
Speaker 2:I think logistically that's very difficult. So I I you know, we've had some wind challenges. Jeff's gonna talk a little bit about greensnap. Adding to that stress by running a sprayer and an auxin herbicide. I worry about some of the other effects that that kind of an application may cause.
Speaker 2:You know one good thing about our corn crop is it's tall and lush and I'm just hoping we're not getting a lot of seed production deep in the canopy. Hopefully those plants aren't able to flower and make seed. But one good point that we do make especially for the small grains producers and maybe for some of the producers that lost fields from standing water, we've got to be absolutely certain that we're not seeing any late season weed production in those fields or weed seed production. So I would encourage our producers to actively manage their small grains fields post harvest and that may even carry over to the dry bean people when they take dry beans off. So let's make sure that we're actively managing, fields into the fall.
Speaker 1:Yeah. And last quick thing before I turn it over to Jeff, just one quick comment came in from folks that, of course, obviously, if you don't have rain, maybe the priest didn't weren't as active. They had a little concern about status, as a growth regular not working as well. And I think some of that could be heightened weather related, I I think, in a nutshell. Would you agree?
Speaker 2:I think so. I wasn't aware of that so, I would like to hear more about that one. Yeah. But that certainly could be a possibility. The active ingredient in status is dicamba.
Speaker 2:Yeah. So, one other quick comment before we transition, Dave.
Speaker 1:Yes.
Speaker 2:Our soybeans are either at the flowering stage or have completed flowering or are at the R3 stage making pods. We're done making Liberty applications, Enlist 24 D applications or Roundup applications. So I just wanna say if there's anybody that thinks that they're gonna try to get one more application in, I think it's way too late for that. Let's push on and plan our post harvest strategies or our strategies for 2026.
Speaker 1:Okay, maybe we can come back to that. I'm gonna switch over to Jeff and bring Jeff on. Well, the the corn crop, talking to people at FarmFest, most people say it looks very good. As a whole across the state, there's a lot of variations, Jeff, areas of Western Minnesota got a lot of rain, in in Northwest Minnesota in some spots, other places does not. We had a lot of rain, almost too much in the Morris area.
Speaker 1:But, as a whole, what's your impression on the Minnesota corn crop this year?
Speaker 3:It looks good. It looked really good before we had this wind event come through on the evening of July 28, but overall, looks good. Most corn's in the dough stage. Some of the later planted stuff is still in the late milk stage. At this point, the kernel number is set.
Speaker 3:So if we have any stress on the crop now, that's only going to reduce kernel weight, not the number of kernels that we harvested. You know, one thing that we're seeing out there is that the crop looks green from top to bottom. We're not seeing the typical, loss of lower leaves due to the drought stress and nitrogen stress that we've seen in the past few years. So that's looking good. Generally, good stands, but in some fields, we are having we are seeing uneven emergence.
Speaker 3:So we do have some late emerging plants, and those are characterized by those thin stocks. And when we had that wind event to come through on the evening of July 28, those late emerging plants with the thin stocks, had root lodging. So down in Southern Minnesota, we got hit pretty hard with this. So those late emergers had root lodging, but the plants that emerged early or on time, they looked they stood up to the wind. However, we did have quite a bit of green snap.
Speaker 3:Down in the Waseca area, we had about five to 10% of the plants were snapped below the primary ear. So that's basically a complete loss on those plants. And then we had about 5% of the plants were snapped right above the ear. And on those plants, probably looking at least at 50% yield loss, if not a little more. And on those plants where we had, snap the stalk snap below the primary ear, that secondary ear shoot right below that one, that one took over and started to grow, and in a lot of cases did get, pollinated.
Speaker 3:But I don't think we can expect anything from those secondary years. So that really took the the top off of our yields. You know, I was thinking at Waseca. In that area, we have 240, in some cases, 260 bushels per acre in the fields in the small in these plots. But with this, wind event, that's probably gonna take about 10% of the yield off the top.
Speaker 3:So, that's bringing it down, but still, definitely, it's gonna be a respectable yield. With regards to, crop development, we are about two to five days ahead of normal. It's just been a little bit of a warmer year overall. And we have had plenty of rain, and it's been a humid last month. So even though we've had some warmer days, the temperatures haven't actually been that high, and we've had quite a bit of humidity.
Speaker 3:And when we have humidity, the plants don't use as much water because there's more water in the air, and the plants act as a straw between the soil and the air. And, with more humidity, the plants don't use as much water. So that's, that coupled with all the rain we've been getting has really led to a soil profile with quite a bit of moisture in it that I think is pretty much gonna carry us through the rest of the year. Big challenges at this point other than the wind. You know, we diseases are starting to show up in corn more and more.
Speaker 3:Although, late last week at Waseca, I did was surprised not to see too much, leaf diseases, given the humidity and everything. Just wasn't a lot there, but I'm hearing reports of, gray leaf spot and southern rust, you know, growing. And I saw some of that, but, it's still pretty low levels. And I think in Iowa, they've, noted that, southern rust is basically present in every county. So, you know, it's there, but is it at a high enough level to cause yield loss?
Speaker 3:Probably not in a lot of cases. But, you know, couple that with some of the other diseases and, you know, we'll just have to kinda wait and see how things develop over the next, month here at this point. But, overall, I'd say the crop looks pretty good. We're in about as good a shape as we could be. It's just unfortunate that we had that wind event come through.
Speaker 3:And other people that didn't get that wind in this last round, some of them got hail and stuff too, and that tattered up the leaves. Maybe bruised the stocks a little, but, overall, I think we're looking pretty good. And the yield estimates that we're seeing, that are being reported the last few days by DTN, Progressive Farmer, those groups, I think they're right on with what they're recommending for Minnesota, which is in the neighborhood of 200 bushels per acre state average. So that's very respectable, and it could have been higher. So, I think that's kind of where we're at.
Speaker 1:Yeah. We just had one question in, and I think we've already covered, and that was, observations about Southern Rest that we just discussed, quite a bit of it in in places in Iowa and showing up now more in in Minnesota. You know, it's been a phenomenon. I think it's been just the last couple of years. Jeff, if you go back in time, you know, eight, nine, ten years ago, we didn't really see it here.
Speaker 1:We thought it was more of a Southern, United States, phenomenon. But nonetheless, it's something that that I'm sure plant breeders are are looking at. It's on a lot of fungicide labels as well, possibilities. We're going in here to now. I noticed, just this morning, it's cooler temperatures.
Speaker 1:We've got a lot of dew. We've got a wet canopy in corn and soybeans and other crops here in the morning, for a couple hours and in in through the night, so that'll make a a factor. We're still not out of the woods yet for hot temperatures yet. We're increasing here, so I think things will, still progress, with that. I was gonna ask you a little bit about, colonel depth and and development.
Speaker 1:Typically a little bit earlier, sometimes we're worried about what we call a a tip dieback or or aborting kernels at the end of the of the of the year. Are we far enough along where that isn't going to occur as much, but if we're gonna use lose yield, it's gonna be more on depth colonel versus, you know, colonel abortion at the end of the tip if we get stressed here in the month of rest of August. What's your thoughts on that?
Speaker 3:Yeah. Exactly. At this point, the number of kernels are established. We're not gonna have any more kernel abortions. So, stress now is just gonna reduce the size of those kernels.
Speaker 3:You know, even if it does get warm, I think we got the soil moisture levels to support us. So unless the temperatures get above the low nineties, it's not gonna be that big a deal. And if it's humid, when it gets warm, that's even better because that's gonna help to offset some of that temperature stress a little bit. So I think we're sitting pretty good.
Speaker 1:Yeah. I I think your comments too about, plant stability, whether it's from wind, there's some concerns sometimes about, corn on corn, corn rootworm, certain events perhaps from a BT standpoint, maybe not holding up as well in situations with that. But that's an opportunity. I know it's not not a difficult thing to do, but, looking at roots this time of the year, I think perhaps. I don't know, what's your thoughts if did we really have shallow rooted corn per se with all the rain, or does that corn tend to be pretty normal, in in, rooting depth, you know, from year to year?
Speaker 3:I I think the roots are fine. I mean, you know, maybe they're not as deep as in a drought year, but I think we got good establishment at the base of the plant in the top foot. And so I and I don't think it's gonna be much of an issue. It's just those fields where we've had, you know, hail damage or other things that's caused the stocks to be weak. You know?
Speaker 3:Those fields, we probably wanna target an early harvest. And, you know, if you got hit hard by the wind, you could walk out there and just kinda see how well the stocks are hand doing. If you have root lodging, it'll be very noticeable. But I think that's mainly only gonna be on the late emerging plants with the thin stocks.
Speaker 1:What's your thoughts? There's some predictions. We discussed before we started here this morning a little bit about black layer, in in terms of that. And maybe we can just discuss with people a little bit when what what does that really mean when we hit black layer in terms of physiological maturity and, any more, development as far as yield is concerned?
Speaker 3:Yeah. So when you hit black layer, yield is basically established. There's no more, carbohydrates being transported into the kernels, and that black layer, basically, it's an abscission layer, and it cuts it off. So, basically, nothing else is being pumped into that kernel. At that point, it's physiologically mature.
Speaker 3:I think we're probably gonna hit that about two to five days ahead of normal, so I can kinda use that as a a general guideline. Probably what or maybe mid September in some places. Depends upon latitude where you're at. Yeah. Somewhere in that area.
Speaker 3:Mid September to September 2224. Okay. Yeah. I I think that's some
Speaker 1:of the earlier predictions for parts of, of of Central Minnesota, like, on an average, like, a hundred day relative maturity hybrid, with that. Anything else that people should think about looking at their corn to kind of plan for next year in terms of seed selection, variety, plant population? Any things that you've noticed or recommend that people, when they look at some of those yield data and plots, think about, well, what should I do differently for next year?
Speaker 3:Not necessarily. I would say the big thing is look for hybrids that are consistently top performers in multiple trials. So look at trial results from a number of different trials in your area and try to identify hybrids that are consistently yielding, say, in the top 20%.
Speaker 1:Okay. Great. Thank you. Tom, any additional things that we didn't touch on about Weaves that you wanted to mention here as we close? You're you're muted, Tom.
Speaker 1:Tom, you're muted. There you go. There you go.
Speaker 2:I'm good, Dave. Thanks for, the question, though. And, I did I was in the q and a, so I did answer some questions that that came in while, Jeff was speaking.
Speaker 1:Okay. Great. Great. Because there were a couple of those and and late ones that we did, did talk about. Okay.
Speaker 1:Well, we have reached the end, not only of today's program, but we've each reached the end of this season's crop strategic farming field notes program. So, again, we would like to thank for today's program and the sponsors of Minnesota Soybean Research and Promotion Council, as well as the Minnesota Corn Research and Promotion Council. Again, we remind you that when you log off today, there's a three question survey. Won't take you too long. We will be back again in the spring of, 2026, but before then, we'll be talking about strategic farming in our winter series, and, we're looking at early January, the start of that program.
Speaker 1:So, keep please keep note of that. Those a little bit be a little bit longer programs, usually in in an hour. We'll have a couple of different guests and so forth, and, we'll be providing information.
