Weed management in fall and what to do with weed escapes
Welcome everyone to the fourth episode of twenty twenty for the University of Minnesota IPM podcast series for field crops. I'm Doctor. Anthony Hansen, hosting today, and today we'll be talking about weeds. We have a new hire to the University of Minnesota, Doctor. Devlin Sarangi.
Anthony Hanson:He's an assistant professor and extension weed scientist. So thanks for talking to us today, Doctor. Sarangi.
Debalin Sarangi:Thank you, Anthony. Thanks for having me. And, you have mentioned I started recently, in late July. And previously, I was, working as an assistant professor in extension weed specialist at the University of Wyoming. So it is really great to be in the state of Minnesota and working with EU and all other extensive folks around, and it's a great place to be.
Anthony Hanson:Yeah. So you're just starting out pretty recently then. So what, areas have you been working on before you came to Minnesota in terms of weed science?
Debalin Sarangi:I got my PhD in weed science from the University of Nebraska Lincoln. And after getting my PhD, I spent a little bit of time in the South in Texas A and M University at, College Station, Texas. So, after that, I took a position in Wyoming and then I came here. And mostly, in my career, I was working on biology and management of different weed species, including, waterhemp and other pigweeds like palmer amaranth and, johnsongrass, giant fragweed. So those are the weed species I was working on.
Debalin Sarangi:And mostly so for my career, I have evaluated their biology, like when they emerge, how they respond to different management practices, and how we can control them using traditional integrated weed management tool like tillage and herbicide and their interaction, as well as some of the innovative tools like the new technology like harvest weed seed control, whether that is feasible in, in The United States for different crop. And for my biology part, I worked on the response of different weed species to adverse climatic situation like water stress. Also, I worked on gene flow, like how the resistant weeds herbicide resistant weeds are spreading in The United States or in the Midwest mostly. So those are my major biology of weeds work. And I spend a significant amount of time working on pigweed species like waterhemp and Palmer amaranth.
Debalin Sarangi:So in Nebraska, these two are the biggest challenge for the growers due to their evolution of herbicide resistance. In the South, in Texas, the Palmer Amaranth is also a big problem. So I got plenty of opportunity working with these two species, identifying their status in those states and how they're impacting the crop yield. And and some of the time, I mean, the infestation of Palmer Amaranth or waterhemp may cause total crop failure, whether it is soybean or cotton or corn. So those are my previous research experiences.
Anthony Hanson:So what are your plans for Minnesota here where, you said you just started officially in July, but I'm sure you have quite a few plans on the ground already for Minnesota for what you wanna look at or maybe things you have started already just to start off in the fall here.
Debalin Sarangi:So last two months, I was, traveling different parts of Minnesota, and I was interacting with the growers. But you can understand the situation with this COVID and all those limited interaction. It was a little bit difficult for me to travel and talk with different growers around Minnesota, but still I was lucky enough that I got some good people, some of our state regional extension educators, and support from, soybean growers association and other research and extension centers and other scientists, my colleagues. So they kind of helped me to connect with different growers in different parts of Minnesota. And I talked to them to understand what is going on and what are the burning issues in Minnesota regarding the weed management problems.
Debalin Sarangi:What I have understood that it is the same all over the Midwest. When I was in Nebraska, growers used to tell they're struggling to control the herbicide resistant weeds. And it's basically a similar problem here in Minnesota. And recently, we have conducted, one of the surveys and, that University of Minnesota Extension. And we saw that less than 10% soybeans are grown in Minnesota.
Debalin Sarangi:Conventional soybean means they are not, resistant to or tolerant to any of the herbicides. So now you can understand when you are growing a herbicide tolerant soybean, there is expectation that you use certain herbicides in a a large volume. And that's the cause of all the herbicide resistant weeds, evolution in the Midwest or in The United States or in the world even. Previously, in 1995 or '96, you know, there were all the glyphosate resistant crops came and we used so much herbicide or the glyphosates specifically. We got, glyphosate resistant weeds everywhere.
Debalin Sarangi:And now we have other technologies like dicamba tolerant soybeans or enlist soybean and corn. So we are using all those growth regulators and we now learned from our previous mistakes, but still we are using a heavy amount of those growth regulator herbicides. So, I can see in the future there'll be more stacked resistance and it's coming. I talked to the growers, I talked to other regional extension educators and they're saying that the stacked resistance is coming in the weeds. In the future, the weed management will be more complicated and challenging.
Debalin Sarangi:So I think, that's the main theme for my research and goal because I identified the major trust area for weed management research in the state of Minnesota. And now my goal is to serve the stakeholders in the state and how I can serve them better. So my goal is to do some of the research on integrated weed management tools because, you know, last thirty years, there are no new sites of action for herbicide in the market. So we are basically relying on all the existing chemicals, and we are basically mixing them to make some cocktails and spraying them. Those are good at this point, but, you know, in future, they may not be the sustainable, way for using the herbicide.
Debalin Sarangi:So that's why, I'm proposing the integrated weed management tools. So, basically, you have your big hammer, which is herbicide, and that's the most powerful tool for weed management. And then you can supplement that with some other small tools like many little hammers. So like a tillage, row spacing, cover cropping, harvest weed seed control. So all those small tools may, make your herbicide choice more sustainable.
Debalin Sarangi:So my goal is not to replace the herbicide because it we can understand. This is the most easy button as well as it is the most, powerful tools in the weed management. And my goal is to make that, finite herbicide choices more sustainable so that you can we can use that, until we have something, new or new sites of action in the market or even in the future, you know. And if you want to manage certain weeds, you have to understand its biology, like how it it behaves, when it emerge, and when it matures and produce the seeds, how much seeds it can produce per plant. So I will give you one example.
Debalin Sarangi:Okay? So giant fragweed, we have seen mostly it emerge early in the season, like from, April to June. That's the period you can see that most of the giant fragweeds are coming up in your field. However, if you see waterhemp, it starts emerging in May and it continue until late August. And sometimes if the temperature and moisture is good, you can get some emergence in September.
Debalin Sarangi:So that's the key. Like, you have to know what weed species you have on your farm and as well as, how you can manage them, by integrating that their biology knowledge with your management choices. And so that's another goal for my, my, program would be to identify the weed species and, understand its biology. Then cover crops. So we saw that there are, a lot of interest among the growers.
Debalin Sarangi:I talked with them and they expressed that they want to grow cover crops. They understood that continuous green thing, harvested your corn or soybean or other crops, you have a bare ground, and that, kind of promotes the germination of the weeds in the field. So they're, looking for something which will kind of give a shedding effect to the weeds so that they don't emerge in the fall or early spring. So cover crop is one of the good choice. There are some research in Minnesota, but this cover crop, its success depends on the localized data.
Debalin Sarangi:So when you see the data from, suppose, Indiana or Tennessee, that may not fit, with the situation in Minnesota. So my goal is to get some localized data regarding cover crops through my research and, applied work. And finally, as I told you that herbicide resistance is a really big issue in, Minnesota as well as Upper Midwest. So, I want to know, like, what is what are the herbicide resistant weeds in the state? And it's always better to document those things because that's that's how you can, serve the stakeholders better.
Debalin Sarangi:And it is the information growers also need to know, what are the resistant weed species on their farm or in their area because these herbicide resistant weeds, if you know, like, okay, I have waterhemp and this is resistant to, glyphosate and ALS chemistry like classic and raptor, and also, PPO chemistry like Flexster or Cobra. So if you know, like you have registered waterhemp to three sites of Axon, you can plan accordingly. Okay. So which herbicide may work for managing this weed species? So I think it is very important to document this herbicide resistant weeds in the state.
Debalin Sarangi:And, over the years, my predecessor and other weed scientists, they, put their effort doing that work. But, you know, with all the changing management practices and all the new treated crops, the the stacked resistance is coming. So it is really important for, us to screen those population and check if they are resistant to one herbicide sites of action or two or three or five. So that's the goal. And, also, I want to create a a special distribution map where we can, show the stakeholders that, look.
Debalin Sarangi:This is the herbicide resistant weeds in your area. So, watch for them. And if you can control them well, for this year, probably next year, you will have less problem. So these are, kind of the area I, figured out that I want to work and my programmers want to serve to the stakeholders in Minnesota.
Anthony Hanson:So in previous years, we've had your predecessor, Doctor. Jeff Gonzales on earlier in the year, but we might have some benefit of doing this in the fall because we can sort of do a little bit of a inventory of what weed issues came up in 2020. I know you've started kind of partway through the summer, but what are some of the key problems you've heard that we've had in 2020 for weeks especially?
Debalin Sarangi:Yeah. So the majority of the weeds, they vary by areas like when where you are. Like, if you are in the Northwest Minnesota, you'll see mostly the waterhemp and kochia, and common ragweed. Those are the problem. And if you come to the South Central part, it will probably be waterhemp and giant ragweed.
Debalin Sarangi:So so these are the weeds, we saw this year, when I talked with different people, when I traveled to different parts of Minnesota, when I surveyed some of the fields. So these are the main weed species. And now the some of the key issues regarding the weed management, what I have heard is, one is the, weather because, you know, the weather is uncertain. Sometimes you get too much rainfall. Sometimes you get less rain, and you cannot really predict, like, whether the rain will be earlier in the season or late in the season.
Debalin Sarangi:So I talked with some of the growers and they told that some some of the time the weather didn't allow them to plant early or spray any pre emergence herbicides on the ground. So that that's a big problem, but we have least control on that. But what we can do is we can get ourselves prepared, like, if there is any adverse weather situation, what are the rescue treatments we have, or what are the alternate management options we have. So I think that's, one of the thing I have heard from most of the growers. And definitely, you know, weed management is, getting complicated even if you are using only herbicides, even if you are not doing the integrated weed management, still it is complicated nowadays because, you have different traits of crops.
Debalin Sarangi:Like you have English crop, you have, extent crop, you have roundup ready crops, so and you have some conventional crops. So with all those traits, first, you have to identify what are the type of seeds you are planting. So that is a big thing. We need to keep track. Otherwise, you may, misapply some of the herbicides that may kill some of your crops.
Debalin Sarangi:And second thing is, mixing issues. Like, because we are recommending mixing different sites of action of herbicide. But now the issue is sometimes they're not compatible. So once, if you don't know or if you don't read the level carefully, sometimes you can mix one herbicide with other and then you can see some sediment in your spray tank or so it may ruin your spraying operation. So those are, another biggest challenges.
Debalin Sarangi:And then carryover because we are recommending the growers to use lot of pre emergence herbicide or soil residual herbicides. Even we are asking them to do the layering applications like, tank mix, the herbicides with post emergence herbicide, like, residual herbicides with the post emergence herbicides. And that that may cause, some carryover issues for your subsequent crop or the next year, depending on how's your weather. So so nowadays, if you are even using only herbicides, still it is more complicated. And, I know growers are really concerned about that.
Debalin Sarangi:Then I told you that pigweed is the biggest challenge for us in Minnesota. And recently, we saw the news last few years, palmer amaranth is popping up in here and there, and mostly they are coming from either manure or feedstock when we are importing them from Southern states because they have big problem with the palmer amaranth. But I want to really thank University of Minnesota Extension and Minnesota Department of Agriculture. They're collaboratively to prevent this weed species coming to the state, and that's a big effort. It takes a lot of time, a lot of resources.
Debalin Sarangi:But so far, I think we are successful eliminating every single report of Palmer amaranth in the state. So but I know the growers are really concerned about this weed because this is a weed species which is not comparable with any other weed species because this is aggressive weed. This is highly competitive. So it's better if we can keep this weed seeds coming to the state for, at least longer period of time because eventually it will end up in our state. If we can delay its infestation, that would be a good idea.
Debalin Sarangi:Overall, I can tell you that the major weed management issues I have heard is herbicide resistant weeds on the farm. And I cannot tell you when the new herbicide sites of action will come to the market. But what I can tell you is we still have some of the tools that those will be really viable tools and strong tool if we, use, one or two of them in a growing season.
Anthony Hanson:So we're moving into fall now. Is there any sort of planning that farmers should especially be doing now or in the winter for their weed management? Either planning for some things they could still do this fall or plans for spring when conditions are fit?
Debalin Sarangi:Yeah. So for the fall or, spring, the best idea would be stout and remove the, weeds that you can see, on your farm. So this is probably the right time because, it's September and this time most of the weeds are producing seeds. So if you go out and if you can see some of the weed escapes, I would strongly recommend that you remove those weed species. I'll just give you an example.
Debalin Sarangi:Okay? Waterhemp. So a single waterhemp plant can produce more than a million seeds. So now think if you have one plant and that will produce 1,000,000 or 2,000,000 seeds per plant, those all those seeds will go to the ground when you harvest your soybean corn. Sometimes when you're harvesting soybean, you can see the weed seeds can be spread out easily with your combine.
Debalin Sarangi:So it's always better to scout your field before harvesting and remove the weeds by hand because or by clipping them and bury them, deep so that those weed seeds will never come back to your farm and show up in the future. So that is a good management practice for keeping your weed seeds to the soil seed bank. And, then if you are suspecting that you have a big amount of weed escapes and if you are suspecting it is herbicide resistant due to the herbicide resistance, you can always contact me or any regional extension educators and send us samples. Sometimes fall application of herbicides or cover crops may suppress your weeds. If it is a winter annual weeds or if it is late emerging, you know, waterhemp or something, you can kill them by applying a one shot of fall application of herbicides or, planting cover crops.
Debalin Sarangi:And again, I'm telling you, waterhemp can emerge from May to August or even September. So the late emerging waterhemp may be really tiny plant and it may not cause any yield, loss for your corn or soybean. That's true because, they're really tiny to compete with your fully matured plants. But the only issue is those small plants, can produce five to 10,000 seeds per plant, and that will go back to your weed seed bank. To reduce your weed seed banks for the next season, it is better to control those late emerging weeds at this point or, after harvest.
Debalin Sarangi:And for the next year, in the spring or early summer, I would say that pre emergence herbicides, we are recommending to the growers and it is very important to have, any pre emergence herbicides. So don't skimp on your herbicide, options because if you reduce the rates of the herbicide or if you reduce one one shot of herbicide, like, if you think, like, okay, I'll skip the pre emergence. I'll just go with the post emergence. Probably, that is not a good idea because having a pre emergence or preplanned burn down herbicide with residual activity will give you a little bit longer window for application of post emergence herbicide because only the post emergence herbicide will only be effective if you spray the herbicide before the weeds reach to four inch, weed height. So you have to spray pre emergence herbicide that will give you a little bit longer window that you can apply some of the post emergence herbicides.
Debalin Sarangi:And we are recommending for layering the pre emergence herbicides. Like, you'll apply pre emergence herbicide and some of the pre emergence herbicides like dual two Magnum or Outlook. I mean, I'm not talking about a specific brand or herbicide, but I'm just giving you example. Those herbicides are residual herbicide. You can use as pre emergence as well as you can tap mix those herbicide in your post emergence treatments.
Debalin Sarangi:And then it will give you some more period for weeds like waterhemp. And then your soybean or corn will close the canopy. Once the canopy is closed, you'll get very few emergence in the later in the season. So it is better to layering those residual pre emergence herbicides. And we are always recommending growers to rotate, rotate, rotate means please rotate your crops.
Debalin Sarangi:Please rotate your management options, like adapt any IWM approach. Please rotate your herbicide sites of action. So if you are using Roundup as your post emergence treatment, try to pack mix it with some other herbicide from different sites of action or use pre emergence herbicide prior to your Roundup application so that it will bring some diversity in the sites of action in your herbicide management choices.
Anthony Hanson:You mentioned earlier about looking at distribution maps possibly for Minnesota, and you've also mentioned before in conversations we've had in the past about a survey you want to do for Minnesota. So you want to give the listeners a overview of what the survey is you're looking at and what they can do to possibly help out with it?
Debalin Sarangi:Yes. So we are we have started a weed survey in Minnesota. We, along with some of the regional extension educators, we initiated this effort this fall, and we'll continue to do that in the coming years as well. So what we are doing is we are requesting the stakeholders to let us, know that if you see any weed escape from your pre emergence or post emergence herbicide treatments. And we are mostly focusing on the weeds like waterhemp and other pigweeds and kochia, lambsquarters, giant ragweed, common ragweed, and barnyard grass.
Debalin Sarangi:Those are the species we are looking for, but those are not the only list we are looking for. If you see something else that some other weed species you suspect they're resistant, please let us know. We would love to come to your field to get some of the seeds, or you can just take those weed seeds and bag them in some paper bags and drop it to some of the extension regional extension educator, or you can directly ship it to me to St. Paul Campus. Our address is 411 Borlaug Hall, 1991 Upper Beaufort Circle, St.
Debalin Sarangi:Paul, Minnesota 55108. And my phone number is (612) 625-8130. So you can give me a call if you have any questions. And, also, my email, you can find it on, University of Minnesota website. So it is, dsarangi,dsarangi@umn.edu.
Debalin Sarangi:So, yeah, feel free to ask me any question if you have any questions regarding this lead survey, but we are really looking for serving the stakeholders in Minnesota better. We want to serve the weeds for herbicide resistance. So what, I can tell you the procedure, what we are doing at this point. So if we see any field with lot of weed escapes from herbicide applications or if if we get a report from a grower that, some weed escapes are present, so we are going out to that field, taking some of the brown paper bags, and we are collecting all the weed seed heads. So we are just clipping the top part for the weed species, and we are kind of putting them in the bag.
Debalin Sarangi:And we are, recording some of the information like GPS coordinate of that, collection site. And if the GPS coordinate is not available, we are requesting the stakeholders to submit at least the address of their farm so that we can kind of locate where from the samples are coming from. And then we are collecting the name of the crops and name of the weeds. And then if the field history is available, we are collecting that information. Because that will be important to know because what are the crops you are growing last five years, and what are the herbicides you have spread this year, whether this weed escapes you have seen last year or this is the first year you were looking for this weed escapes.
Debalin Sarangi:So any kind of field history we are collecting if available. And then we are bringing those samples to St. Paul Campus. We are growing the weeds out of them in the greenhouse, and we are spraying them with different doses of certain herbicides, and we are checking whether they're resistant to one or multiple herbicide sites of action. Also, we are planning to send some of the selected samples to genomic, for genomic analysis.
Debalin Sarangi:So we have capacity doing that, at Saint Paul Campus, or we can send that to some of the other state like Illinois or Michigan or Colorado. They can do that, small cost, and, I can cover that cost from my program. But this is the way we want to document the information of herbicide resistant weeds in the state. And, also, I want to prepare a map for the special distribution, And those results will be shared with the stakeholders in different extensive meetings and through some of the publications. And I think it will help us to plan better, like, what are the management practices or herbicide options we can have to, manage these certain weed species.
Debalin Sarangi:Again, if you see some of the weed escapes on your farm, please contact me. My name is Devlin Sarangi. Please contact me or contact any of your regional extension educators, and they will send out the sample. They will go out in your field or I can come personally and get the seeds and bring it to the St. Paul campus and screen them for you.
Anthony Hanson:We'll also have your contact information posted on the Minnesota Crop News blog that's associated with these podcasts whenever we update a new episode. I think you also have more information on that blog for some separate posts too, so there'll be some more weed information coming out for people who follow that part of University of Minnesota Extension. So thank you, doctor Saragi, for coming to talk to us today. And with that, I will end this fourth episode of twenty twenty, and we might have one or two more episodes coming up this fall still, and we might be looking to having a little bit of fall and winter programming since we couldn't get quite as much in earlier this spring. We might have some good listening for you when you're out doing work this winter or just taking easy inside.
Anthony Hanson:Thank you again.
