Field Crops Webinar Series - Field Crops Webinar Weed Management in Hay and Pasture Fields - Cassida Burns
March 14, 2022
- All right, everyone. Well, I have seven o'clock. So we're gonna go ahead and get started. Welcome to the sixth week of the Field Crops Webinar Series. My name is Jenna Falor and I am a Field Crops Extension educator out of the Thumb of Michigan. With us today we, oops. With us today we have Kim Cassida who is a forage and cover crop specialist with MSU as well as Erin Burns who is a field crops weed specialist for MSU. Welcome and thank you for being with us, guys. As with most presentations here, I'm gonna put the slide up here. MSU is an affirmative-action, equal-opportunity employer, and we welcome everybody to come to all of our programming, regardless of anything listed there. After today, we have two more field crops webinars on this series. If you have any interest, the topics are on your screen. And at the end of this, you will have, at the end of this presentation, if you haven't attended one with us before, you will be at a survey link, and that will take you both for your feedback and if you are here for any of those RUP credits. That link will be sent out in the chat toward the end here. If you have any questions throughout the presentation, please feel free to put those into the Q&A. If they're pertaining to what they currently just finished covering, we'll answer those as we go. If they're unrelated or something they may be covering later, we will hit them at the end. And with that, I will hand it over to you, Kim. - Hi, everybody. Let's just get my screen share set up here. (mouse clicks) Hopefully you can all see the title slide now. - Yep. - So, I'm glad everyone could join us here tonight. I am the forage specialist primarily for MSU. And I've been here for about 10 years and really have seen quite an uptick in last few years of questions about weeds compared to when I first got here. So we have also with us here tonight Dr. Erin Burns who is our weed specialist for forage crops and she can give us a little insight into this problem. So, Erin, what is it that makes these weeds such a problem in our forge crops? - Well, Kim, that's a great question. So we thought we'd start off our night talking about weeds in forages and talking about kind of what makes them unique in this system and how do they really exploit the system and take off? So the first is that they have rapid establishment, growth, and then ultimately seed production. As you know, in a lot of our forage systems, we have repeated grazing and cutting, which is number three, but that's really linked to the first one is that these weeds need to be able to complete their life cycle within all of those stressors that you're putting in on these systems. And secondly, they're very good at colonizing poor conditions. So things like low pH or poor fertility, which we'll touch on later of why some of these weed species like that and some weeds that can actually tip you off on you might have some soil issues. Also compacted soil, high traffic areas, or any of those bare spots that may come up, the weeds are just great at exploiting those. It can also be toxic to livestock. So maybe they don't have big impacts on yield, but it could be toxic or have spines and make them often unpalatable or have certain chemical components in them that make them just not tasty to those animals. Often we do have noxious weeds in forage systems. And noxious weeds are categorized in addition to being kind of a problem agronomically in reducing yield and competing with your desired forage. They also can have impacts on the environment and human health. So those are a special category of weeds, and there are noxious weed laws in the state that prohibit you from having those in your fields. And then also they can reduce marketability of hay, which, Kim, I think, you can maybe touch on some implications of having weedy hay. - Well, I'm going to talk first about having weedy pastures. (Kim laughs) - There you go, - Because we're going to actually spend, a lot of our talk tonight is going to be focused on getting the weeds out of your hayfield because of the marketing issue. But I just feel obligated to point out here that not all weeds are bad, especially when they're in a pasture. And the reason for that is that many of our common broadleaf weeds are actually quite nutritious. People have done forage quality on weeds and discovered that in many cases, they're just as good as alfalfa. The trick is getting your animals to eat them. Now when it's in hay, you also have to sell it to the person who's paying for the hay. The animals might eat it in the hay just fine, but the people don't wanna see it in there, so you're not gonna be able to sell your hay. But you can teach animals how to eat weeds. And this is beyond what we can cover here tonight with our time limits. But I do wanna point you towards a book called "Cows Eat Weeds" by Kathy Voth. And I've been to some of her seminars over the years, and I can attest that this is a method that actually works. So I've got, here on the slide, a picture of the cover of her book with a cow, but the sheep with her mouth full of Canada thistle is in my flock. And I've successfully used her method to teach my sheep to eat a lot of different kinds of weeds in the pasture. So if you're interested in that in a pasture system, I would recommend you to look up her book or look at her website and learn more about how to do that. But you do have to be careful with horses. The trouble with horses is that they're a lot more sensitive to plant toxins than cattle, sheep or goats are. And that's because of the way their digestive tract is set up. And so you have to be a lot more careful about the weeds that you feed to them, where a lot of things that you might be able to feed to the ruminants, you can't feed to a horse. But fortunately here in Michigan, we have relatively few of those weeds that are what I consider zero tolerance weeds in a pasture, or actually in hay or haylage either. And that's because of their toxicity to horses for hoary alyssum, which is only toxic to horses. But then we also had poison hemlock and spotted water hemlock, which are two weeds that are actually moving north into the state. These are often found on the borders of fields and these are quite toxic. Poison hemlock was actually the plant that was used to execute Socrates many, many (chuckles) centuries ago. And these are not things that you want your animals to eat. Also white snakeroot, cocklebur, and nightshades can be problems. Most other weeds can be tolerated depending on the degree to which they're affecting your yield, forge quality or your ability to sell your hay product. Now we do get the question from a lot of people of like, well, okay, this is all interesting, but I didn't have weeds before. And now I have a lot of weeds. And we have a couple of things that have been contributing to that. And in my opinion, as a forage agronomist, the biggest thing that has contributed to the flood of weeds that we seem to be having recently is the crazy weather we've been having. So we all know that the weather in Michigan is quite erratic, but it's been even more erratic than usual the last few years, and plants do not like this. Remember that most of our forage plants are our perennials. We don't replant them every year. We plant them once and we expect them to survive for a really long time. And when they have situations like fluctuating temperatures and precipitation, really stresses them out. So in the past few years, just the last three years, we've had, in 2019, we had all that flooding. Not good for our plants. We followed that up with 2020, we had a lot of winterkill, bad winter conditions that summer or, that summer, winter. And then we followed that up with quite a severe drought in many parts of the state in 2021. So we've had three years in a row where our forage crops have not had good growing conditions and that weakens them. And then the weeds can come in. Another reason is our management choices, and I'm not even gonna call this bad management, because in many cases it might not necessarily even be a bad management choice. It's the choice you made for some reason. And it might be suited for some other purpose, but you have to understand how it might affect the survival of your forage species. And one thing that we see quite a lot of is just people are trying to grow a species that's not suited for the site or the weather conditions that they're trying to grow it in. A classic example of this is alfalfa, which has almost zero tolerance of poor drainage. Yet people still try to grow it on a poorly drained site and that is just a recipe for failure and weeds. We do have this bulletin that if you Google the name of this, you can look this up online, and it's got some charts in it that will help show you which forage species are suited for which types of sites, like for drainage, drought, cold weather, things like that, so that you can try and pick species that are appropriate for the field you want to grow them in. Another thing we see a lot of is marginal soil fertility, talk about that here in a second. And then also your harvest management decisions have an impact. The issue with fertility is that hay crops in particular remove a lot of nutrients from your soil. They remove actually more nutrients than almost any other crop you could grow because you're taking almost the whole biomass off that field and you're selling it. So that is mining nutrients outta your soils. And depending on the species that you're growing, you may be removing 60, about 60 pounds each of nitrogen and potash, 17 pounds of phosphate, and up to six pounds of sulfur per dry ton of hay that you harvest. And so you can see that if you've got a six to seven tons per acre hay yield, those numbers are gonna go up a lot. Those nutrients have to be replaced somehow. If you just continually harvest hay without putting any nutrients back, with the exception of nitrogen, obviously, 'cause if you have alfalfa or another legume, they can get their own nitrogen, but the other things have to be replaced. The good news about a pasture is that grazing animals actually recycle about 85% of those nutrients in the grass that they eat. Only about 15% is gonna leave the field when you sell your product, your animal or your milk or whatever you're selling. So there's not quite as much strain on the system, but there's still some. Also need to consider that forage crops differ in their nutrient requirements. I just mentioned legumes like alfalfa. They don't need nitrogen added, but grasses do. Grasses need you to feed them nitrogen. And again, nutrient-stressed forge crops can't compete with weeds. Like Erin mentioned earlier, the weeds are really, really good at dealing with poor fertility. That's kind of their special niche and the forages can't compete with that. So that's the reason why we will recommend that you soil test your hay fields and pastures every three years, at least, or you can, instead of soil testing, you can do a tissue test on the forage about every three years. And that will help you monitor your soil nutrients and maintain adequate fertility for the specific species that you're growing. Because the soil test will come back with recommendations for what you need to apply to make up for the yield you're expecting to get. Another thing is harvest management. And this is where there's really a trade off. The issue here is our perennial plants, they have to have a chance to recharge their nutrient stores in their roots after every harvest, whether that's hay cutting or animals have grazed it, or however it was removed, they've got to be able to restore those roots or the plant cannot be a perennial. It will die, because it needs those stores to regenerate itself. And when those forages are weekend or die out to make a bare spot, that's when your weeds come in. In pastures, again, this is kind of outside of the scope of this particular talk, but we do run a grazing school each year, usually in the fall, where if you're interested in learning more how to manage pastures, I'd recommend you to watch the events, and consider attending that. But in general, if you have got more than 500 pounds of animal live weight per acre in Michigan on your pasture, it is likely that unless you are an outstanding pasture manager, that your pasture's probably overstocked and overgrazed and might look like the picture on the top here, at least in places. Now alfalfa in particular is a little bit of a different story, because we like to cut alfalfa on short intervals, because it improves the forge quality for things that we need like dairy quality hay. And so you may decide to do it, but you have to understand that that is going to make a trade off on the ability of the plant to tolerate weeds, because it takes alfalfa about 35 days usually to restore those root reserves. And so this picture over here on the bottom is from a trial that we finished up a year or so ago where we had alfalfa stands that we were cutting every 28, 35 or 42 days for three consecutive years. So what you're looking at here is spring of the fourth year when it was starting to green up. And you can see quite clearly here in the front that the plots that were being harvested every 28 days, no matter what, have a much more severe infestation of dandelions than the ones that had the longer harvest intervals. And again, you may need that for the quality of the feed you need to harvest, but you also need to understand that's gonna increase your weed problems. (chuckles) So, Erin, you mentioned earlier that there are some weeds that can help give us clues to what sort of problem we may be looking at so. - Yeah, yeah, there's some great ways to be kind of a sleuth in your field and do some detective work to see what some of these indicator weeds are for problems. So there was a study that looked, it was in the University of Missouri. So they went all over Missouri and sampled pastures for both pH and fertility. And then they counted the number of weeds that were there and then what species there were. And what they found was that the common ragweed was often associated with low pH fields. And amazingly what they found is if you just went from pH 5.8 to 6.8, so up one unit, that resulted in less than, or 4,000 less weeds per acre, which is a pretty amazing number and 245,000 less common ragweed plants. So pretty market difference if you're able to increase your pH just that one unit. And, Kim, when would you recommend people soil test if they're worried about low pH fields in some of their forages? - Typically for forage crops, I like to see people do their soil testing in the fall. And the reason for that is because we know that it takes, an application of lime takes about six months before it's gonna significantly affect your actual pH of your soil. So if you soil test and apply your lime in the fall, it can be doing its thing in the soil over the winter while your plants are dormant and be ready to help you when you have things green up in the spring. - Cool, all right, well, let's go on to the next one. - Oops, sorry. (Erin chuckles) (Kim chuckles) I forgot to advance. - That's all right. So next is low fertility. So usually when we get emails or calls about weeds, Kim or I, the first question we ask is, do you have a soil test? That's probably like 99% of the time our response, 'cause usually, I mean, a healthy forage stand doesn't have it, they're highly competitive against weeds. And usually there's something unique going on, so low pH or here is low, low fertility. So things like potassium and phosphorus, Dandelions love those situations. And they're a good weed just in general, 'cause they can withstand a lot of the cutting, but lots of times we'll see that associated with low potassium and phosphorus. So that's one of our first things we ask you. So if you have questions, that'll be number one. And then lots of times, if you don't have a soil test, you can go do one. And then we can kinda make a game plan to how to adjust those parameters to make sure your forages take off. And then also there's soils in which you would just, you obviously can't change markedly the texture of your soil. There's ways to increase organic pattern, things like that, but if you're on pretty sandy soils, there's more some weeds to watch out for, and just be aware of, and do some scouting. So things like horsenettle, which is the top left picture on your screen. It has giant spikes. I've spiked myself with those plants before and they're not pleasant. So lots of times we'll recommend making sure you are out scouting, having a shovel too. So this is a great one to, you have just one, you can pop it out of the ground. Also spotted knapweed. So I usually exclusively get calls about spotted knapweed and that's associated with these sandy textured soils that drain pretty well. So these are just weeds to look out for it if you're in those systems, have a plan. And then the opposite side is poor drainage. So having implications on not being able to grow your desired forage, but also weeds that can withstand that. The top left picture is horsetail so not to be confused with marestail. So horsetail is equisetum. It actually looks like little Christmas trees. So it's much different and it's an ancient plant. And it can withstand saturated soils quite well. Annual bluegrass is another good one. Mosses can occur. And then our rushes and sedges are also pretty good flags of knowing that you have some drainage issues, not only being able to see how wet the soil is, but see what weeds end up invading those areas. And then also wheel traffic. So this is a pretty cool picture Kim took back in 2019 and if we remember back to 2019, it was really, really wet. And we had a lot of delayed planting and that meant delayed cutting too. So this was cut on five weeks late. So this is July in the upper left. And you can see that this soil was still too wet to be going over, but they needed that forage to, I believe, feed the dairy cattle on farm. So they just, at campus, so they just went ahead and did it. And then you can see later in October what came in is those are grassy weeds. So there were bare spots that were left from that wheel traffic and compaction going over the field. And then the weeds will take over. So things like dandelion, plantain, annual grasses are good at coming up. And if you have weird patterns, so this banding pattern, which you could pretty much overlay with some of this wheel traffic, that gives you an idea that you maybe went on that field when the conditions weren't right. (chuckles) - So how, the next question is, people go, well, I didn't have weeds before and now I have them. So where did they come from? (Erin chuckles) - Well, those weeds are always there and that's 'cause there's a concept called the soil seed bank. So the soil seed bank are all the seeds that are contained in your soil, just waiting for the right conditions to germinate. So soils actually contain thousands of weed seeds per square foot, which would be amazing if they could all germinate at the same time, but because of different dormancy and viability and other parameters, they don't. So the weeds that are in the soil seed bank can come from mature weeds that set seed during that year, so those are the weeds that you saw with seedheads in this figure, such as a dandelion. It produces seeds. Those seeds go into the seed bank. Some can germinate and some will actually just stick around for up to a few years and they can germinate later on. And then we also have new additions from animals and wind and things like that. So there's two ways, weeds, and then also us, and humans. And we'll go over a bit of those in a second. So what we do on campus if you, and you can do it at your house, if you wanna know what weeds are in your soil, you can go out and shovel and dig up some soil. You can put 'em in flats or if you have like a cake tin or something like that, and then water it and see what comes up. So that's a picture on your right, as we pulled soil samples from a number of different fields, and then you just see what germinates. And that gives you kind of an idea of what might come up. So this might be something good to do if you're going into a field that you don't know the history of too well. And then there's also that looking at how long weed seeds can remain viable in that soil seed bank. So things like common lambsquarters, they take about 12 years for 50% of those seeds to deplete. Amazingly some can stay up to 80 years. So there's some weeds, it's very small percentage can do that. Things like common ragweed have a pretty quick, their viability isn't as long. So about one year and half of the seeds are already dead. And then things like pigweeds about three years. And then I couldn't find a time for 50% for hoary alyssum which is a pretty problematic weed, but about nine years for that seed viability. So just showing you kind of a range of seeds that can stick around in your soil seed bank. - So another way that the weeds can get into your fields, aside from being already there, or carried in by Mother Nature, is that you can help them get there. And one of the common ways that this happens is by seeds hitching a ride on your equipment, because anytime you take any kind of a truck or a tractor or any kind of hay-making implement out there into the field and it's just come from some other field. And maybe not even recently. Maybe it's been sitting in the barn over the winter with weed seeds stuck all over it. But you then take it into another field and those weed seeds fall off and now they're in a new field. So one of the things we usually recommend is that if you have a particularly bad weedy field, that you should try and clean your equipment off after you leave that field before you go back into a clean field with it. And it might be something worth talking to your custom harvesters about too, because of course you have no knowledge of where they came from. So they could be bringing you a present that you didn't anticipate from some other client's field. - And the next good way that weeds move around and that are unique to these system is manure. So anytime you're applying manure, you wanna know that there is a chance that there's weeds in there. So this study looked at, they fed a certain amount of weed seeds to various animals, and then looked at the number that they could recover in the manure and then actually how viable were they? So could the weeds make it through that system and then could they actually grow? So things like field bindweed makes it through that system pretty well. So any seeds that are small and have hard seed coats can generally make it through animal systems. So followed by Pennsylvania startweeds, we still had 26% for things like calves and horses, but then you can look at the number that's in the parentheses is the viability. So even though they made it through, those were less viable than our field bindweed. And then red sorrel, pretty low numbers. But when you look at the bottom, chickens are amazing at (chuckles) taking out weed seeds. So, Kim, why do we see these differences depending on what the manure source is? - A lot of this has to do with the way the digestive tract of the animal is. So animals that chew more thoroughly, or in the case of chickens, they grind their feed in their gizzard, which is full of little stones. And apparently grinding seeds in little stones is quite effective at destroying even tiny weed seeds. Whereas something like a calf or a cow or a horse or sheep, they don't chew their food nearly as thoroughly. - So we just need to have more animals with gizzards. - Gizzards, yeah. - We'd have to come up with a pretty cool invention. And then we also wanted to mention Palmer amaranth. So that's a very aggressive pigweed species that we have in parts of the state. And what we think of how that actually got here was through contaminated feed that was then fed to animals. And then they excreted that In the manure, and then the manure was spread all over the fields, and that propagated the issue. So I couldn't find a study that looked at how money were recovered, but how much were viable. So from things like cattle, about 27%, which is pretty high, and then chickens actually 3.5. So just to show you the percentages. And if you think of one plant, some of those plants can produce up to a million seeds. Just having a few seeds around and having that escape throughout the season can be a great way to move around weed seeds that you might not have had an issue with before. - Yeah, well, I'm just gonna take this opportunity to make a comment about that, but that's one of the reasons why Erin mentioned earlier that if you just see one weed in a field, get a shovel and dig that sucker out of there and dispose of it somewhere. Don't throw it on the side of the field, 'cause some of those plants can mature the seeds sittin' over there. Get rid of it, because just that one plant, say you just had one plant of Palmer amaranth show up in your field and it makes a million seeds and spreads 'em all over the place, you can see that it doesn't take very long for you to have a much bigger problem. - Yep, and it's easier to do if you don't have the weed than after you have a big problem. - Another way that weeds can get into your fields and pastures is through seed. Now if you're buying certified seed or regulated seed with a tag, one of the advantages of that is by law, that seed has to be screened for weed seeds. So you will look at your label, you will see things like on this alfalfa label, that it's been counted and determined to be 0.04% other crop seeds. That just means anything other than alfalfa. Might not be a bad plant, could be orchard grass or something, but you don't want it in there. And you've got 0.03 weed seeds and you see there is a separate category for those noxious weed seeds, which Erin mentioned earlier is being the ones that are really, really bad that actually are regulated at the state level. So you can have some information that the seed has been screened for that. Now if you're gonna use bin run for seed or off-market forage seed, or just something that your neighbor harvested and you bought it for cheap, it might be economical, but you just have to be aware that you are taking the risk, that you are bringing whatever weeds were in their field, you're now bringing those into your field, because in lot of cases, that seed really isn't even cleaned very effectively. So just keep that in mind. There was an instance a few years ago where, pretty well known, the NRCS was actually using a seed mix that they got from I don't know where that had been inadvertently contaminated with Palmer amaranth. And they were promoting this for use on conservation reserve land and ended up spreading a lot of Palmer amaranth around the state of Minnesota. So you just have to be really careful with this. And now we're gonna finish up by talking about a couple of case studies. We can't talk to you about every kind of weed that you might possibly have. I'm sure we're gonna be addressing some of those questions in the question and answer session, but we tried to pick two particular weeds that we commonly get calls about and discuss a little bit about the specifics. So the first one here is hoary alyssum, which is an example of a toxic weed. But as I mentioned earlier, it's really only toxic to horses. And again, this has to do with their digestive tract. They can't detoxify it. Whereas cattle, sheep and goats can. But this particular weed has a toxic in it that can actually cause the death of horses, both when it's grazed fresh in the pasture and also when it's eaten dried in the hay. And when it's dried up in the hay, it looks a lot like alfalfa. It can be really hard to identify it. And it's basically gonna stay toxic in the hay for the lifetime of the time period that most people are gonna be feeding a batch of hay. And we have seen here in the state that horse owners have become pretty educated about this and they have zero tolerance right now for buying hay that has hoary alyssum in it. So if you are marketing hay to that market, you really have to be pretty careful about this weed. So Erin is going to give us some suggestions about what you can do. - Yeah, yeah, so in general, so hoary alyssum's an annual, which means it can complete its life cycle in one season, but there are also instances where it can be a short-lived perennial. So that means it can live multiple, multiple years. Often the conditions, it can thrive in sandy fields with poor soil fertility. So as we covered earlier, making sure your nutrients are right, but I will say it can invade pretty healthy fields too. That's why one of this weed is so difficult to control. But ultimately you'll see there aren't that many great options, for herbicide-wise, to control it. So making sure your nutrients are right and maintained and that you're having the appropriate, either cutting schedule or grazing is really important to make that whatever you're growing as your forage is as competitive as as possible. So this is a fact sheet that was put together by MSU a number of years ago. And I checked that there's not really any additional options. So herbicides did a good job for a while and then we haven't discovered a lot of new ones. But on the table you can see that, what type of forage, so is it broken up by grasses or legumes? Do you apply them post to that, or you can actually apply dormant herbicides to dormant alfalfa and then crop tolerance. So one would be, it's pretty safe up to three or four that you'll see some crop injury. And then the use rates and then how effective it is. So you can see for seedling legumes, we don't really have very many good options. Established legumes, the only options you have are dormant season applications, which can be effective if you're applying 'em at the right time, so that for the, Kim can touch on later, that alfalfa's broken dormancy, some of the injury you might see. And also that only controls early season flushes of these weeds. So any weeds that might come up later, so let's say you have bare spots in your fields or weakened stands, this weed will continue to germinate. So you won't just see it right away. And I wanted to note that many pastures and hayfields grown for horses are grass-legume mixtures. And maybe, Kim, you can touch on why that's becoming a pretty popular practice. - Well, what we see with the mixtures is they have a number of benefits for improving forage yield and quality, protecting the soil, fixing nitrogen, preventing soil erosion. Many reasons why they can be a good thing, but they have this one big bad thing, which is, (chuckles) it makes it really hard to put any kind of herbicide out there. - Right, so when you grow these mixtures, you effectively have no herbicide options, 'cause herbicides are selective. So herbicides are good at, if you're growing it broadly, so let's say you're growing alfalfa, we can kill grasses pretty easily, 'cause we have herbicides that do that. If you're growing grasses, we can kill broadleafs pretty easily. But once you mix those together, you reduce all your herbicide options, 'cause you have both of those broadleaf and grasses together. And our herbicides just aren't that amazing at somehow keeping both of those functional groups and then still killing the weeds. So you do have, and I've scoured all over, 'cause I get this question all the time, what can I use in these mixtures? And I always wanna come up with a better answer. And I don't have a good answer. And I've reached out to weed science colleagues in Wisconsin, Minnesota, Penn State, kind of the foragey regions to see what their answers are. And they were all the same too. So I felt my due diligence in trying to find a good answer. So the only one you can use is metribuzin or Sencor and you have to apply that dormant season. And it does okay. So it might set it back a little bit, but by no means is it going to control hoary alyssum or broadleaf Canada thistle. So any broadleaf weeds in general. So - Yeah. So I'd just down a little. - Yeah, yeah, yeah, which is sometimes good. So that gives your forages a little time to jumpstart and grow, but it's not a silver bullet. So when I do recommend this, you gotta make sure your alfalfa is dormant. And that knowing that you'll still probably have that weed is an issue. And then the second case study we wanna go over is Canada thistle and that's 'cause Canada thistle is a noxious weed. So one that you're prohibited from having and have to show that you have some that you've tried to control it. And what makes Canada thistle so problematic is that it's a perennial. So it emerges in the spring and then flowers later in the fall or later in the summer when the days are longest. And that local reproduction is through this creeping root system, which you see on the right-hand side, I did some Canada thistle work for my masters. This is plants that I just dug up and then followed how many shoots came off of that creeping root. And it can be quite a few. And that's a really good way that it invades. So if you, by chance, see one Canada thistle plant, like that's amazing, and that means that that seed just landed in your field. So when we were talking about shovels, that's one I would dig out pretty darn quickly. And then they produce these seeds which are attached to these little feathery papillae. And that's how they can disperse farther distances. And then they can infest your fields. And then to note, tillage and mowing, and other kinds of mechanical control are not highly effective. On the tillage side, you can add actually move the root fragments around, which is not good. That's a really good way to spread it. And then mowing can also kind of knock it back, but you need to mow at the right time, because oftentimes when we mow Canada thistle, it'll actually stimulate all these root buds to then germinate. So you wanna make sure, usually, we advise mowing it when it at least has buds, 'cause that means that it's used all this energy to produce those flowers. And if you can remove those, you're at least damaging the plant a little bit, but know that it's gonna come back. So you need to be pretty meticulous at your mowing scheduler or cutting schedule if you're trying to control Canada thistle mechanically. - Yeah, and I just wanna point out before I change the slide that this is a problem in both hayfields and pastures. It's probably one of our most common weeds that we face here in Michigan. But also I'll remind you that it's one of the ones that is quite nutritious for animals if you can convince them to get past the spines and eat it. But pretty much in hay, you don't wanna see it. Nobody wants to buy hay with Canada thistle in it. (chuckles) - No, not so much. (Erin chuckles) And Canada thistle in grass forages, you can actually, there are herbicides that are used that can suppress it. So that means it can help slow it down and keep it from spreading rapidly. But once again know that if you do have a pretty heavy infestation, you need to make yearly applications of these herbicides and you need the herbicides to be systemic, which means they actually move throughout the plant so that it's schematic. On your screen right now, just a herbicide to do its job at Canada thistle is you need to damage that creeping root system. So if you can get that herbicide down there, that'll have the biggest implication. And you wanna do this at bud or bud to bloom stage or early in the fall. And that's just when the plant is still moving around at sugars, and doing its thing. And that's how the herbicide will also follow that. So exact herbicides, you can use things like Cimarron Plus or Crossbow. They're highly effective, but they have long soil residuals. So you wanna make sure you have a plan in place for those fields for multiple years to ensure that what you might wanna plan in two years isn't impacted by that herbicide application. And then there's a number of herbicides that contain chemicals that have longer restrictions. So things like Milestone, Grazon or Stinger are all, once again, highly effective at controlling Canada thistle, but they have many restrictions. And, Kim, can you give us an idea of what some of those restrictions are and the implications of those? - So the implications for that particular chemical for hay crops is that while the chemical is very effective at killing the thistle, there will also be some of it on the grass (chuckles) that you harvest and it retains its activity in the hay. It won't hurt the animals. It's legal to feed it to animals, but it goes through the animal, comes back out in the manure and that manure remains toxic to all broadleaf plants. So the concern has happened because, for example, horse owners would buy hay treated with this and then they would sell their manure to a vegetable farm to use on whatever, and that manure would kill the vegetables. (chuckles) Because the residual remains in that for a very long time if it's being and applied to a sensitive crop. And also this one, like some of the other ones, it has basically a sole residual of 18 to 24 months where it will continue to kill new Canada thistle or other broadleafs that come up, which is great for helping to control your Canada thistle. But say if you wanted to come back into that grass field and reestablish a clover in it, you're not gonna be able to do that until that residual is gone. And that is a rather long wait. (chuckles) - Yeah, so if you're havin' these issues that we, before applying, we just recommend knowing what your plan is for that field longterm and what your market is. - Yeah. And you are required by law, if you sell hay that has been treated with Milestone, Grazon or Stinger, then you are required to notify the buyer of the restrictions. Of course you can't control whether or not they follow those restrictions themselves, but as you can probably imagine, when you have to notify a buyer of a particular herbicide and all these restrictions, they're quite likely to just decide they're not gonna buy your hay. (chuckles) 'Cause they don't wanna deal with it. - Then I just wanted to highlight the resource that we have, which is the Weed Control Guide for Field Crops. And we do have a forage section in the weed control guide and you can find that on our website and we'll give you the URL at the end. So if you're only interested in forages, I'd recommend going downloading the PDF and just printing off the few pages that forages are. If you're wanna know about other field crops, definitely buy a copy. But just to show, so this is a snapshot of what the weed control is for herbicide and forage legumes. And we have it just broken up by the herbicide. If you can use it in seeding legumes established, or if you need Roundup Ready alfalfa, and then there are different weeds. And just to note, you can see that many of our perennials that we've been talking about today, so things like Canada thistle, field bindweed, we don't have any good herbicide options for those that are effective really whatsoever. So an N would be none. And a P is for poor. F is for fair. And then anything that's bolded a G or E means 80% control, control are better. And we also have a section for grasses also. This is just a good resource to have a snapshot of what you might be able to apply. - Yeah, and there also, in that guide, there are detailed sections for particular scenarios of what you might or might not apply to a particular forage crop. But by far the most work has been done with alfalfa. - Yeah. Agreed. Then we just wanted to cover these mixtures again. I get this question all the time. And I know, I think someone already put it in the Q&A, so (chuckles) unfortunately we don't have a great answer. So, Kim, you might, yeah, if you could cover the first few points of why they're used. And once again just go over where you wanna target planting them. - Yeah, well, again, we've talked about this already, but we thought the was important enough that we needed to emphasize it because this is by far, probably the most common question we get about weeds. I have a mixture, I have weeds. How can I kill the weeds? And really unfortunately, like Erin has already said, we really don't have a solution to that problem, but there are really good reasons to use a mixture, because they do increase your forage yield and quality. They help hay dry faster. Putting a legume with your grass will help replace that expensive nitrogen. So you'd fertilizer, so you don't have to buy it. And they have a real benefit for soil health, but you can't control the weeds. So what I usually tell people is this is where you have an opportunity when you're establishing a new field. You want to only establish forages into a field that is already as clean as you can get it from weeds. So you need to know a little bit about the history of the field and what is in it. So you might do something like maybe you grow corn in it for a couple of years, if you have a big Canada thistle problem, and then you can keep hitting the thistle with a broadleaf herbicide that's not gonna hurt the corn and get that cleaned up before you try and go in and plant something like alfalfa in there. Because once you've got the alfalfa in there, you really don't have very many options. So having, and I get a lot of questions right now from people who have just acquired a field. It's like they inherited a field or something and they wanna grow hay on it. And you're really in a hard position if you don't have any information about the history of that field, to know what the weed problems might be so that you can make a decision on what you could do. - Yeah, and that might be a good chance to go pull some soil samples and get it tested and also do some of your own grow-outs to get kind of an idea of what might be there. But I wouldn't put in my, yeah, my mixture off the bat without knowing some history. So just doing- - And the other thing, yeah. - Yeah. - Go ahead. - Go, Kim. - The other thing you can do is you can put a grass in or put in a grass or a broadleaf. Say if you know that your biggest problem is something like roughstalk bluegrass, which is a grass, you could put in alfalfa and do a few years of control to minimize the bluegrass and then go and overseed a forage grass into the stand once you've got the weed grass under control or vice versa. - Yeah, that's a great, great recommendation. And then, yeah, and this is usually what I copy and paste into all my emails when you email me (laughs) about forage weeds is that if you can establish and maintain healthy forage stands, that's the best bet. And they're highly competitive against weeds. I mean, obviously we have years where the weather is unfortunate and things like that. And that's when we get some of these issues. But if you have a good stand or a good pasture, it's an amazing, amazing competitor. - Right, and you have to keep that fertility up though to keep it going. Where we see problems a lot of times is the field will be pretty good at the beginning, but if the fertilizer is not being replaced, so replace what's leaving in the hay, then over time, it just gets weedier and weedier. And fertilizer is certainly not getting any cheaper so. (Kim chuckles) I know it can be hard to justify the decision to buy that fertilizer, but that's, again, one of the trade-offs that you make. If you don't take care of those forage plants, the weeds are gonna have an advantage. - Yeah, and then with that, we just have a snapshot of what both of our websites look like. So MSU Weeds or forage.msu.edu, which we have lots of great resources for weeds in growing forages in general. And then our emails too. So if you have a particular question or this remind you of something, shoot us an email, or give us a call too if we don't cover it tonight and we can start making a plan. (chuckles) - All right, guys, we had one question that you guys kinda touched upon a few times here, but we'll just ask it so you can reiterate it for the specific weed. Are there any chemical slash spray options for controlling Canadian thistle in new or established alfalfa grass mixtures, legumes that are taken to harvest and not grazed? - So yeah, no. (chuckles) No. - No. (Kim laughs) (Erin chuckles) - Yeah, so that would be like the patch of is small, you might wanna think about doing some, man, it's probably not small if you're asking this question, so you're probably past the time when you wanna go dig some, but you could... So non-chemical ways, you could think about potentially mowing at certain times or trying to weaken it that way and then looking at what your fertility is, but those are- - Another thing that you could do with a situation like that, if it's more than one plant, but it's not the whole field, is just take out that part of the field, and basically do a scorched earth there. And you'll end up killing everything and get the thistle under control and then go back in and reestablish a forage crop, which might be a better option than letting the thistle take over the whole field. (chuckles) - And just keep creeping and invading, yeah. - And a lot of times it will be coming in from the edges, 'cause you'll see it a lot of times in fence rows or on the edge of woods. And it's got those underground roots that crawl. And the next thing you know, it's out in the middle of your field. - Right, a lot of these places you mentioned that they take advantage of where you have bare spots, such as where you had winter kill and whatnot. For somebody who has, say an alfalfa grass mix already out there, what would you suggest going in maybe? Would you suggest going in and seeding in a clover or some more grasses, that kind of thing just to make the weeds less competitive? - That is something that you can do. One thing that you have to be careful of, 'cause we see this question come up a lot with alfalfa, and I've done other webinars on this topic, but it applies to this situation as well. Alfalfa's toxic to its own seedlings. So you can't go back into an alfalfa stand and thicken it back up with more alfalfa. You have to give it a break of a year or so before you can plant more alfalfa in there. But what you can do with those bare spots is go in, you could plant something like red clover. You could plant any kind of grass if you just want to cover up those bare spots so that the weeds can't get going in 'em. And you'll see a lot of people actually in the fading years of an alfalfa stand, they actually will go out there and overseed it with a grass or maybe even something like oats, if they want it for short term just to fill in those bare spots and give them a little bit more life outta that stand. Just don't try and do it with more alfalfa. (Kim chuckles) (Erin chuckles) - Good advice. Another question we have is I understand that oftentimes goats will eat weeds preferentially. So if I have some troublesome weed species in my pasture for sheep or cattle grazing, can I send in the goats if I don't have chemical options and I don't yet want to reseed? - Actually you can do that. There are actually people who run businesses that are nothing more than putting their goats in a truck and driving them around to eat weeds. Usually in more residential areas. But it could be done anywhere that there was a weed. Because goats do like to eat a lot of that stuff. Although I have a flock of sheep, and I've worked with goats as well. And I actually find that my sheep will eat almost anything that a goat will eat. Goats are probably a little bit better at eating woody weeds. We haven't really touched on those here, but goats, mixed-species grazing is actually a really good way to address weeds because a lot of animals will eat things that other animals don't like. So calling it a weed is just a, that's something that we have as an idea. It's like, this is an undesirable plant, but to the animals, as long as it has nutrition in it, they don't care. (Kim chuckles) - The next question, and unless anybody adds anything, this is the last question that we have here is what herbicide would you use for horsenettle? - Horse, that's another great question. And unfortunately the ones that are highly effective at controlling horsenettle are the same ones that we covered for Canada thistle. So things like Grazon or Milestone are affected. So you have those restrictions in place. Also you need to spray it before there's berries on the horsenettle plant. So that's when I get the call (chuckles) is, the horsenettles have those bright yellow berries and that's when I wanna control it and so I then don't spray it- - That's when they noticed it probably. - Because that's a waste. You're just wasting money spraying it when it's at that point. So it's kinda unfortunate to see them all go to seed like that. But then you'd know you have a problem the following spring and have an idea of where some of those patches are. So I've told people that even if they, on GPS, mark, put a pin on their Google Maps of where they were at, so they remember in the spring that they have an issue and then they can apply some of those when they're smaller. But know that you have some of those restrictions or if there isn't any desirable forage nearby, so if it is on like an edge of a field or something like that, you can use Roundup. Just know that Roundup will kill anything it touches. So it's one of those that'll just kill everything, but does a decent job at some of those smaller horsenettle plants. - And sometimes it can be worth it. And also I just wanna point out too, 'cause I don't think we remember to say this anywhere, but it is really, really important to identify the weed species that you've got, because they have specific life cycles and you have to know where is the right place to hit it? (Kim chuckles) So in a lotta, with the exception of Canada thistle being one that's good to apply when it's at bud or flower, but most of the weeds are not very effective to apply herbicide at that point. And all you've managed to do is kinda kick it in the butt on its way out the door and it's already done its damage. So that's really important to identify the weeds and know when is the right time to control that particular one. And you really don't wanna let 'em make seeds. - No, we're here to help. So take pictures and send us emails. And Kim and I can either identify it or we have a number of other people on campus. So if we can't, we forward those on and someone will have a good idea of what you're growin'. - So we've had a few more come in here if I can figure out how to get back to 'em. (Jenna chuckles) First one being, assuming that I do not have any noxious or poisonous weeds, but I have a lot of weeds. At what point would you recommend tearing up a field and starting over? - Probably when you're not getting the desirable yield out of it, but that would probably be, Kim would probably be able to know when to pull the trigger on that. - We've actually got some guidelines that we can apply to that. If it's an alfalfa field, for example, we can look at the stand density. You should have more than 40 stems per square foot, or at least five plants per square foot. If you're less than that, your stands are already on the way out. You'd probably be better off to just start over. With our grasses there, NRCS actually has an excellent publication that is actually on my website in the extension section. It's called "How to do Condition Scores on Pastures." But I would just ignore the word pastures, because I find it also to be very good tool for evaluating the condition of mixed-species hayfields, because it's got standards in there. It'll actually tell you how to go out there and score it and say how much bare ground you have, how vigorous are your plants, and all of those things are important in a hayfield as well. And that gives you an objective way to determine whether the field is so bad that you should start over. But you can also do that a little bit by eye. Like if you look at the field and all you can see is weeds, that it's probably time to start over. (Kim chuckles) (Jenna chuckles) - Next in reference to the spot spraying that you had mentioned for packets of weeds. If somebody were to do that, would you always recommend reseeding those areas so the weeds don't become competitive in them? - Yeah, if you have, if it's just like a tiny area, no, but if it's any kind of a sizeable area and you don't replant it with something, it's just gonna turn into a weed patch, because the seeds are there. - So the seed, yeah, they're ready. - (chuckles) They're ready. - And sometimes they just need that light or open space to germinate and take off. So for sure don't leave big spots, but if you're killing a weed or if you went with a shovel and popped one out, that's not a big deal. - The next question we just had come in is can anybody buy van Banvel 2,4-D ester? - So, I mean, probably just talking about like herbicide shortages in general is maybe what this question is getting at. And we know that with various supply chain issues right now, a lot of different chemicals are hard to get your hands on. So that would be a time that you could probably shoot me an email or gimme a call and tell me what your weed problems are and what herbicides you can obtain. And maybe can we make a plan based off of what you can actually get your hands on. So that's what I've kind of approached this year with just given how difficult some herbicides are to get these days. - I think part of that question, and I could be misinterpreting is, are those restricted use? - So have that in the weed control guide too. And I'd have to, I mean, look exactly to remember if one of these are, so we have a whole table that goes over, that says if it's restricted use or not. And if you'd need any extra certification to do those. And I'm just trying to pull that up right now, because I have my weed control guide in front of me. - Somebody else just tagged in and says, they believe they're both general use. - I know for sure, yeah, 2,4-D is, and then Banvel's been around forever. So that has also not restricted you. So thank you for whomever chimed in, and you are right. (chuckles) (mouse clicks) - And Janice who chimed in that also put out there, if you don't have a relationship with your local co-op, et cetera, you can buy both of those at Tractor Supply. - Well, you can if they're stocked. (Erin laughs) (Kim laughs) - The inevitable question this year, right? - Yeah. - Yeah. - And with that, we had a couple people raise their hands, but they haven't been able to fill in any questions. So if you were one of the people who raised your hands and you had a question, please feel free to go ahead and shoot any of us an email and we will make sure that gets redirected either to Erin or Kim if you email me or directly to them and we'll make sure you get an answer on those. Oh, we have another one. Experience tells me that it takes a massive dose of glyphosate to kill horsenettle. - Right, yeah, so don't go low. So you need to use, depending on what your formulation is, like 32 to 48 fluid ounces, which Roundup is hard to get your hands on glyphosate this year. So if you do have it and you have decided that that's how you wanna use it, don't skimp out, because (chuckles) you'll just kind of make it mad and slow it down a little bit and then it'll continue to grow. And also don't apply it when it has like even the start of berries on it, 'cause that's oftentimes when I think also sometimes people just apply it too late and it's not as effective. - All right. Well, perfect. It looks like as of right now, that is all of the questions that we have we have in, and that being said, I wanna thank everybody for attending here. And if you check the chat, the link for the survey and your RUP credits is in the chat. So go ahead and do that. Again, thank you, Erin and Kim for being here with us today. We really appreciate it. - Well, thank you all- - Thank you. It was fun. (chuckles) - For tuning in.