Field Crops Webinar Series - Overcoming Weed Management Challenges in 2016

March 22, 2016

MSU Extension Field Crops Webinar Series 2016
Session 1, 2/22/16
Title:  Overcoming Weed Management Challenges in 2016
Presenter:  Dr. Christy Sprague

Video Transcript

>> Speaker 1: OK. Good evening once again. And welcome to the MSU Extension field crops webinar series. By name is James DeDecker. I'll be your host for this evening. And tonight we're lucky enough to have Dr. Christy Sprague with us for a presentation on overcoming weed management challenges in 2016. >> Speaker 2: All right. Thank you, James, and first of all I want to welcome everybody tonight. Basically we're going to talk about some of the weed management challenges that we've been seeing around the state. And really specifically focus on two particular weeds and spend a little bit of time talking about both horseweed and also waterhemp. These two weeds were weeds that I definitely had the most phone calls about this last summer, and there are some key things that we need to really think about when we start managing these weeds. And I'll spend a little time talking about a little bit about the biology of both of these weeds and what are some of the options we do have for management in some of our field crops. And particularly, mostly, we'll talk about corn and soybeans. But there are definitely...we do have information on some of our other field crops that are out there. So, I would say that Horseweed by far is one of those weeds that we've seen explode in Michigan over the last two years. Last year I spent a lot of time talking about a method to manage this weed. And we still continue to see this as a problem. We had several soybean fields that looked like this with Horseweed throughout them towards the end of harvest, and this became an increasing concern as we drove around the state. Just to give you a little bit of background about Horseweed, we many people will call it Marestail; it's basically the same weed. This is a winter annual; also can be a early spring emerging weed, and that we generally see it come up anywhere from August all the way up through April the following year. Many times in the spring we'll see the rosette of Horseweed that will show up like this picture in the upper left hand corner. Once it starts to grow a little bit more, it'll...a lot of times you'll see a nice big rosette, and I'll show you a few pictures of those, particularly the ones that come up in the fall. Then it starts to bolt, as you can see in the lower left hand corner. And eventually will start to produce seed. And you can see the seed looks very similar to what you would see on a dandelion. Basically it has this feather-like, and they call it a pappus, and that really helps it travel from field to field, and that's also helping- making this weed become more of a problem in many of our fields throughout the state. This is just some general information about the life cycle of Horseweed. As I mentioned before, it is a winter annual, but we do have some spring emergence of this particular weed. So in general, we see a lot of emergence pretty much as the soybean canopy senesces; anywhere towards the end of August into September. And generally we will see fall germination all the way up to November. Ideally, at this point that those plants are always going to be in that rosette stage, so that also gives us an opportunity to control some of those fall emerging plants. We also see a emergence of Horseweed early in the spring. In general, we usually start to see this towards the later part of March all the way through April, May; and in some cases we've actually seen Horseweed emergence into June. In general, with both the fall and spring emerging Horseweed, we do see it to start to bolt sometime around April for those early emerging plants, and really start to see flowering about sometime in July. And, when that seed really disperses is towards the end of August and through September. Many of the fall emerging Horseweed that we have can survive the winters, anywhere from fifty nine to ninety one percent. So it is a pretter- pretty winter hardy weed. Again, it is a winter annual, so it is able to survive those winters. Another thing about Horseweed that's pretty interesting is it does produce a large number of seeds. Anywhere- in general, we see about two hundred thousand seeds per plant. And I'm, as I mentioned before, each one of those seeds has kind of a feather-like...protrusion from it, which they call a pappus, that can basically tra- help in the transfer of it, particularly in wind. In general, those windblown seeds can travel quite a long distance, and in some cases we've actually, there have been reports of it being actually traced up to the upper atmosphere. Another thing about the Horseweed plant; when it produces seed, they're quite small. And generally, they do germinate from the soil surface, so if you look at this particular slide, you can see these seeds that are on the soil surface- these are the ones that are going to germinate and cause a problem. As those seed gets- seeds get buried- it's tougher and tougher for them to actually emerge. So if you look over here we have a couple different schematics where we say at a quarter of a centimeter, basically we only have three percent germination. And the deeper it goes, we see a lot less germination. And again, over time, if those seeds are buried, they will break down due to a decay and other types of things that can happen with seed. One of the bigger issues that we do have is that we have...several instances of herbicide resistance in Horseweed. In general, we have had, in Michigan, ALS-resistant Horseweed. We've had two herbicides in the ALS-inhibiting family that have been very good to control Horseweed in soybeans, and those were FirstRate and Classic. And there are several premixtures that have Classic or chlorimuron in there, but with the ALS resistance, we started seeing more and more Horseweed becoming a bigger issue. In the last several years, we've seen the glyphosate resistance expand in our Horseweed populations in Michigan. And several of the populations that we do have in Michigan have both glyphosate and ALS them. And in general, we do have a diagnostic clinic here on campus, and Dr. Erin Hill is now doing our herbicide-resistant screening. This year she received eighteen different samples from different places. And from her initial results- she's been able to test twelve of ' one hundred percent of those have become- are glyphosate resistant, and seventy five percent of them have both glyphosate and ALS resistance, so that is a big concern as we move forward in trying to manage Horseweed, particularly in soybeans, with the few options that we do have. One of the bigger problems that we have with managing Horseweed in soybeans is that...we are very limited on options for control. This is a chart from our MSU Weed Control Guide. Extension bulletin E434. And if you look at page fifty six, this is kind of our general table of weed responses to our post-emergence herbicides. And if you were to look over at the column that says Horseweed on the far right hand side of the two pages that are next to each other, and you look down, there are, in this first table, we see that there are two- or, excuse me, three different herbicides that provide good control of Horseweed, and these are Classic, FirstRate, and Synchrony. And if you go over and you look at the site of action, you see that these are all group two herbicides. As I mentioned, many of our Horseweed populations have glyphosate resistance, and those are the group two herbicides, so those basically are no longer going to work for controlling those Horseweed populations post-emergence. If we go- look further on at the rest of the table where it says 'in glyphosate resistant soybeans', you can see that many of the herbicides as far as site of action are either group nine or group two. With those multiple resistance issues that we have, it is very difficult to control those. If we look at some of the other premixes, you can see something like Flexstar, which is a combination of glyphosate and Flexstar reflex. And if you go back over here to see what type of control we would actually get with Flexstar, you would see it'd be poor. So again, even though we have these other options, these options are not available for control of Horseweed because they're just not effective. So, in...with the resistance, and just because we don't have any post-emergence options, particularly in RoundUp ready soybeans or non-GMO soybeans, this makes it a really difficult weed to manage...particularly in soybeans. So there are a few things that we can do, and these are management steps that really are important to follow if we look at trying to manage Horseweed in soybeans. The first one is to make sure that we control any emerged Horseweed prior to planting. As I mentioned, we do you have fall-emerging Horseweed. We also have early spring-emerging Horseweed. So if we're planting our soybeans into plants that are already there, we've already lost the battle, because again, there's nothing we can apply post-emergence. Ways to control Horseweed prior to planting. One particular way is with tillage. In general, we talk about tillage, we need to make sure that we have uniform disturbance of the upper few inches of that soil. And as we've moved forward, a lot of people are using vertical tillage units now. Those particular units are not going to be effective in controlling Horseweed; again, we need to be tilling up that Horseweed in order to manage it. And that would be one way to control emerged Horseweed. The other option we do have is to look at using an effective burndown treatment. In particular, if we have a lot of Horseweed that comes up in the fall, we might consider doing a fall application; that way we are basically starting with a...only the spring-emerging plants. So, for example, if we have a lot of Horseweed that emerges in the fall, those are probably the ones that are going to start bolting and getting bigger in size in the spring as some of our newer ones emerge, so if we have a lot of fall emergence, that's where we might want to consider doing a fall burndown treatment, but in general we'll probably have to come back in the spring because of some of those spring-emerging plants. The other thing that we need to do, so, not only do we need to control Horseweed prior to a planting, we also need to make sure that we have a residual herbicide or pre-emergence herbicide in with either that burndown, or after that tillage pass, to make sure that we're controlling any of the Horseweed that may come up after the soybeans are planted. Because we have no post-emergence options. So if we look at some examples for controlling Horseweed prior to planting, in general, some of the things we need to think about is we need to make those burndown applications are best when those Horseweed plants are at the rosette stage. So you can see here, this upper picture, that's a good picture of a rosette Horseweed plant. Once they start to bolt, they get a lot harder to control. The picture in the lower right hand corner is probably showing you a Horseweed plant that's about six inches tall, and those get very difficult to control as they increase in size. We usually generally say we need to make those applications before those weeds are four inches tall. There are two different herbicides in soybeans that we'd consider as kind of our base burndown include. And the first one is 2,4-D ester. This has kind of been the standard treatment for controlling Horseweed; in general, we would apply to 2,4-D ester with other herbicides such as RoundUp or Liberty or some other different things to help pick up control of the other weeds. When we're using to 2,4-D ester, in general, prior to soybeans, we need to make sure we have seven days between that application and planting, and we can't go over a whi- one pint per acre for that application. The other treatment that we have that can also help with Horseweed control is the use of the Sharpen. Sharpen is a contact herbicide; in general in soybeans, we can apply it all the way up to planting, or any time before the soybeans emerge. The use rate that we would use for Sharpen is one fluid ounce per acre. And we need to apply that with a methylated seed oil. And I'll give you a few examples of what I would consider as potentially good burndown options that would include one of these different herbicides. So, when we talk about managing some of our resistant populations, in particular, as I mentioned, we have widespread resistance of glyphosate resistant Horseweed as well as ALS resistant Horseweed, and in many cases the resistance is to both of those groups of herbicides. So we're really wanting to make sure that we're using effective herbicide sites of action. I've kind of broken this down into looking at how many effective sites of action- the more we can use to control these resistant plants, the better off we were- we are. So if we look at different programs that we can use that would just have one effective site of action group, we obviously have 2,4-D. That could be tank-mixed with glyphosate for a wider burndown program. Another particular option we have is that Sharpen with glyphosate, again, and a methylated seed oil; the methylated seed oil definitely needs to be used with Sharpen. The third option that we do have is Liberty, which is another contact herbicide. In if we're using this as a burndown treatment for Horseweed control, we generally want to use it at the highest rate that we can, and again, that's going to be thirty six fluid ounces per acre. And with all these treatments we would add ammonium sulfate. And remember, with our 2,4-D, we need that seven day application window. For better control, we're much better off going with a program that will have two effective burndown herbicides in it. Here are four different options that we do have. We could look at adding 2,4-D to Sharpen with that glyphosate and methylated seed oil. Another option that works out really well is the combination of Sharpen and Liberty. Again, including methylated seed oil. Another option that we- two other options we have is looking at a burner herbicide like Liberty and adding Metribuzin to it; so the Metribuzin would help not only with post-emergence activity on those emerged Horseweed plants, but also would give us some residual control. Gramoxone plus Lib- Metribuzin has also provided very good control. And each one of these programs would have two effective site of action groups. So there are some cases where we've been having some difficulty in controlling Horseweed with either 2,4-D or Sharpen alone. And in many of these cases, if we look at including another effective site of action group, we're much better off in trying to control these resistant populations. One other potential option we have is to look at three different site of action groups. And with this one in particular, we do have that Metribuzin in there, so we do see some residual control, so looking at the combination of 2,4-D, Gramoxone, and Metribuzin. So these are all options that we can use to burn down the emerged Horseweed that we have prior to planting soybeans. As I mentioned, not only with those burndown herbicides...we do need to include a residual herbicide. So with some of those options, we did talk about using Metribuzin; that is a good residual for Horseweed control. Again, if we're using tillage, we also need to be thinking about using a soil-applied herbicide for any of those Horseweed plants that could come up after the soybeans are planted. We have basically two different herbicide groups that we can use; we have the group five herbicides- those are ones that we consider Photosystem Two inhibitors or some of our trizines. And in soybeans, what we really have is Metribuzin. And in general, with Metribuzin, we do have some premixes we can use, but again, the Metribuzin is what is really giving us the control- the residual control of the Horseweed. And in general we want to try to keep that Metribuzin rate up around six to eight ounces. So if we're looking at those premixes we may need to supplement some of those premixes with a little bit more Metribuzin to get that longer residual control. The other option we have is to use a group fourteen herbicide. There are basically three different group fourteen herbicides that have some residual control for Horseweed. We have Flumio...Flumioxazin products; those are our Valor-type products; there are several of those, and there are several premixes. One of the things that we have to worry about is we cannot tank-mix Sharpen with any of these group fourteen herbicides as long as- if we're planting it closer to soy- or, applying them closer to soybeans. So if we're using these tank mixes and deciding we're not going to use 2,4-D and we want to use Sharpen, we- and we're going to tank-mix one of the residuals in with Sharpen- we need at least fourteen days before planting to use these. There is also the Sulfentrazone products; these are a lot of our Authority-type products. Again, also provide pretty good residual control of Horseweed, and there is also again those tank-mix restrictions when applying it with Sharpen. We can also use Sharpen at some higher use rates. But again, we will need that longer time period. And it can only happen on some of our soils that have more than two percent organic matter. So, in general, there are some restrictions based on when we- or what our tank mixes are, and some of the use rates, and when we apply it. So, that's one thing to keep in mind, so if we're thinking of using a group fourteen herbicide for residual control, we might want to consider either tank-mixing that with 2,4-D and having that seven day window, or maybe potentially tank-mixing it with something like a Liberty or Gramoxone. With the Metribuzin, we can tank-mix it with any of the other burndown options that we talked about prior to. As we mentioned before, the more sites of action we have out there; herbicide sites of action that are non-ALS, particularly, on those multiple resistant weeds, the better off we are. So, there are some options of combining things like Valor and Metribuzin. There are some Authority products out there; there's Authority MTZ that has both the group fourteen and group five herbicides. And there are some premixes that again will have both the group fourteen and group five herbicides, as you can see listed here. And, as I mentioned before, we can go with some higher rates of Sharpen, but we would need a longer time from that burndown application, also, to planting, so. Just a few things to consider as we look at trying to manage Horseweed. And again, it's because we do not have anything post-emergence that we can use to control that particular weed. One other option we do have is- if we want to consider having one potential option post-emergence- is to plant Liberty Link soybeans. This is going to be the only option we currently have until some of the new Dicamba packages and 2,4-D resistant soybeans have all gained full approval with the applications of the herbicides; right now Liberty Link is the only option we have to where we can get some post-emergence options. In general, we'd still need to make sure that we have an effective burndown herbicide in there, as well as a good residual to get us good initial control of the Horseweed plants. Because, again, as I mentioned before, once the Horseweed gets any size on it, it's very difficult to control no matter what herbicide you're applying. In general, with Liberty, if we're going to follow up to help control some of those escapes, we're looking at using anywhere from twenty nine to thirty six ounces post-emergence in those Liberty Link soybeans. And we want to make sure that we're making those applications prior to that Lib- to the Horseweed being six inches tall. And, with those particular soybeans, we do have the option to follow up with Liberty. I will say that Liberty is a contact herbicide. As those plants get bigger, a lot of times, if we're not- if we wait until those plants are bigger, we'll just burn off the tops and we'll start to see some regrowth. So again, that is why we need to make sure that we have a good burndown herbicide with a good residual component to it. And these would just be kind of our rescue or insurance treatments. We do have our MSU Weed Control Guide. There was a picture of the cover here, but in general, our 2016 guide on page 199, we do have a fact sheet that kind of lists some of the different options we do have for controlling Horseweed, and basically some of our recommendations. You can also find this particular fact sheet online at And I'll give you that website towards the end of the, the webinar. The next thing I want to talk about is not only the Horseweed issues that we saw from- in 2015, is we received a lot of calls in regards to waterhemp. This is a picture of field that actually had both...glyphosate and ALS resistant Horseweed and waterhemp, so we're looking at trying to manage two weeds that have resistance to multiple herbicides, so you can see, this basically kind of got out of control, and pretty much all we see here is kind of a weedy mess amongst those soybeans. As far as waterhemp, we've, over the last couple years, have gotten a few reports of waterhemp becoming more of a problem. But it hasn't become widespread; this last year we had a lot of calls where people were thinking that they might have Palmer Amaranth or some other issues, and in general when we look back, many of these fields had waterhemp and many of these soybean fields were either apply- Roundup was applied to them, or in some cases Extreme, which is a combination of both glyphosate and the ALS inhibitor Pursuit. And as you can see, many of these plants survive some of these soybean fields. Or- in some of these soybean fields. So this is a picture from a field in Shiawassee County, just kind of showing you some of the pictures that we either took this year or had sent to us. This is Saginaw County; again, a couple applications of glyphosate, and the waterhemp is surviving. This is a field up in Sanilac County. You can see the waterhemp has kind of moved in from the side of the field and has started to spread throughout the field. This is a picture and you can see some dead waterhemp plants next to some surviving waterhemp plants, so this particular population is still segreting- segregating out for resistance. And this happens to be a Lapeer County. This last year we had several samples that were submitted in addition to some of the phone calls that we had, and of the samples that were submitted, for right now, we know that a hundred percent of them were resistant to the ALS inhibitor, so those group two herbecides, and fifty percent of them showed up both glyphosate and resistant to the ALS inhibitors. Erin- Dr. Hill is also screening for atrazine resistance, and there are a few populations that she's re- retesting because it looks like we might have some multiple; another additional resistance in some of those waterhemp populations. The other thing I'm going to mention is Palmer amaranth; again, we do have Palmer amaranth in several of our Michigan counties. And we do have multiple types of resistance profiles. We have some populations that are just resistant to glyphosate or RoundUp, some that are just resistant to the ALS inhibitors, and then we have the multiple resistance, which is pretty widespread with both glyphosate and ALS, just like what we're seeing with the waterhemp and the Horseweed, and then we do have a population that has threeway resistance; glyphosate, to the ALS inhibitors, and also to atrazine, and to some of the other triazines. So, they're very difficult to control as we start looking at what options we have in both soybeans and corn. As I mentioned before, waterhemp was the one where we had the most calls this year. I'm gonna talk about some of the similarities and differences between both waterhemp and Palmer amaranth because they are both pigweed species. On the left hand side of your screen, you can see a picture of waterhemp. In general, the leaves are much more narrow that what we see with Palmer amaranth, which is on the left hand side. Some other similarities that we do see with both of these pigweed species is that they have extended emergence patterns. And basically what I mean by that is they tend to emerge and continue to emerge throughout the season. Here's a picture just showing typical emergence pattern of a weed that we have in Michigan, Velvetleaf, and comparing it to waterhemp. And as you can see, in general water- or, Velvetleaf would come up early and would probably hit its peak emergence sometime in May, and usually would kind of...emergence would drop off by quite a bit as we got into June. But with waterhemp and also our Palmer amaranth populations in Michigan's, we usually see the first emergence showing up about the third to fourth week of May; our peak emergence is sometime in June through July. And we have seen emergence of both waterhemp and Palmer amaranth into August and then sometimes we see an emergence even in September, when there has been light available to- hitting the soil surface and the correct moisture for these weeds to germinate and emerge. Another thing that's very similar between these two pigweed species, the waterhemp and Palmer amaranth, is they both have rapid growth rates. This is a picture that I have shown before from North Carolina showing you how quickly Palmer amaranth can grow. So for example, if you look at the lower part of the picture and you see this orange stake and it says July 6th, 3 P.M., that was the height of this weed that is right next to it. July 8th at 7 P.M. you can see how much- how quickly that has grown, so in two days, that plant has jumped up that high. And if you look at the next morning, so we're going from 7 P.M. at the top of the stake to the top of where that plant is at 7 A.M., so just twelve hours later, you can see how quickly that plant grows. And again, this is Palmer amaranth in North Carolina. So, usually, quite a bit warmer than what we are, but we are seeing quite a bit of growth in our Palmer amaranth populations in Michigan. And in general, we've seen anywhere from a jump from three to seven inches in less than five days. If we look at waterhemp, typically, in the heat of the growing season we will see waterhemp grow anywhere from an inch to an inch and a quarter per day, so these- both of these plants can grow fairly rapidly, which makes it very difficult to time some of our post-emergence herbicide applications. Another thing about both of these pigweed species is they produce a lot of seed. In general, the seed is very similar between both Palmer amaranth and waterhemp. They're both small, black seeds; very round. And we have seen in Michigan some of the seed production that we've seen in Palmer amaranth growing in soybeans; up to 350,000 seeds per plant. Again, this is in competition with soybeans; with waterhemp, they average about 250,000 seeds per plant, so if we're allowing these weeds to escape, we will have problems in the future. Another thing that's very similar about both of these pigweed species when it really comes down to identification- waterhemp and both Palmer amaranth will have both smooth stems. You can see there's a picture of waterhemp on the left hand side of the screen, and Palmer amaranth on the right hand side of the screen, so. These are both smooth stems. Many of the other pigweed species that we have in Michigan have hairy stems, or stems that have kind of a rough feel to 'em; this just happens to be a picture of Powell amaranth, which is very common; Redroot pigweed would also be common. And even smooth pigweed has hair on the stem, so, as you're looking at your fields and you're seeing some of these pigweeds out there, if you want to tell the difference if there is a smooth stem, that's when you need to worry because again, that's probably either waterhemp or Palmer amaranth that you might be dealing with. Another thing that's very similar about both of these weeds and also causes some of the issues that we're seeing with resistance of these weeds is that both waterhemp and Palmer amaranth are dioecious, meaning they have both separate male and female plants. And what that really means is that we see a lot more genetic diversity. And some of those herbicide resistance traits can be spread fairly rapidly because of that genetic diversity. In addition to that genetic diversity as far as herbicide resistance, we also see diversity in how some of these plants can look, and I'll show you a few pictures of waterhemp and how they can look very different just because of this diversity. So with these separate male and female plants, those male plants are producing pollen. And they're sending that pollen off to female plants, so they can basically pollinate several female plants, and spread some of that genetic diversity, whether it's transferring herbicide resistance traits or maybe changing some of the morphological traits as far the phenotypes of each one of these species. Here's a picture of just showing you the seed heads of both Palmer amaranth and waterhemp. There's the male seed heads; if you look closely, you can see the pollen on the male seed pl- male seed heads. You can also kind of look and tell the difference between Palmer amaranth and waterhemp just by the thickness of the seed head; you can see a much thicker in diameter seed head for Palmer than what you can for waterhemp. With the female seed heads, again, these are the ones producing seed. The female seed head of Palmer amaranth is also the one where you'd grab it and it's very sharp or pokey, so it's one of those ones where you just can't hold on, where you don't see that with the female plant for waterhemp. There are some identifying characteristics, and I'll just show you a few pictures. And we do have a fact sheet that kind of walks through some of these differences. So if you look at Palmer amaranth again, this is where our identifying or differences occur between the two pigweed species. Palmer amaranth- our petiole that attaches the leaf to the stem is generally as long or longer than the leaf blade, so if you fold it over and that leaf petiole as- is as long or longer, then it is probably Palmer amaranth. Another thing we do see; the spiny bracts on Palmer amaranth female plants, as you can see here. And then the other thing; as I mentioned before, we have a much thicker, longer seed head for the Palmer amaranth than what we do for waterhemp. With waterhemp, a couple other key characteristics is in general, the leaves are going to be shiny or waxy looking. And they're much more long and narrow than what we see with any of the other pigweed species, so, that is a very distinguishing thing if the seed heads haven't been produced for waterhemp. The other thing as I mentioned before; that genetic diversity. You can see anywhere from red to green seed heads, so there's really no commonality to color. But if you look at what those seed heads look like compared to Palmer amaranth, you see that they're much shorter; much thinner than what you see with the Palmer, so, again, just some very distinguishing characteristics between the two different pigweed species. And in fact, both of these species can grow in the same field. This is a soybean field and you can see the Palmer amaranth plant on the left hand side of the screen and the waterhemp plant on the right hand side of the screen. So, they both can occur in the same field together. So as far as resistant- or, excuse me, at fars- res- managing these resistant plants, as I mentioned, waterhemp was by far the one we had the most calls, and I see that as the one that may take off, spreading more than the Palmer amaranth. We've had Palmer amaranth here since 2010, and it's kind of stayed in those same general ten to eleven counties, and it hasn't really taken off a whole lot. But this year, again, we're seeing a lot more waterhemp and it seems like it's exploding, so these are a few things we want to keep in mind as we look at managing waterhemp and also ways to help manage against having waterhemp be an issue. And when we look at our waterhemp management, it's going to be the same- basically strategies that we've talked about for Palmer amaranth. One of the things that we like to stress is not only just rely on herbicides, but also look at some of our other practices that we can do to make those plants- soybean plants more competitive. One thing we might do is plant in narrow rows and higher soybean populations. This is fifteen inch rows compared to thirty inch rows. And you can see that there was just more light for Palmer amaranth to come up, so this is just an example Palmer amaranth. We also did some work this last year looking at seven and a half inch rows versus thirty inch rows. And, basically from our late season, again, we want to manage this with the best herbicide options that we can. But another way to help manage it is not only with herbicides, but by closing that canopy earlier, and we were able to reduce some of the new Palmer amaranth...emergers later in the season by fifty two percent by using narrow rows, so that's one particular way that we can also help supplement some of our herbicide options that we have to control these plants. Where we do have widespread resistance, one of the things I would suggest is to plant LibertyLink soybeans. Just because, again, we're, we have very few options post-emergence, and some of those options, if we continue to use over and over again, we might see the expanded...more resistance showing up. So when we look at LibertyLink soybeans, one of the reasons we might want to suggest that is it gives us another strategy besides just using our PPO inhibitors like Flexstar and Cobra post-emergence for control of the ALS-glyphosate resistant waterhemp. So, it gives us an additional site of action group that we can use. We can still use the group fourteen herbicides, those PPOs; but it also gives us the option of using Liberty, which is a group ten herbicide. It also provides some aws- flexibility in some of our crop rotation and use rates. And what I mean by that is, with Flexstar, we generally are limited to a pint per acre every other year. And we do have some longer rotation restrictions, particularly, we have four months for wheat, ten months for corn, and we have eighteen months for things like sugar beets. But if we're going to plant LibertyLink soybeans, we still need to follow the steps that we would use for managing waterhemp or multiple resistant waterhemp in both RoundUp Ready and non-GMO soybeans. So one of things we need to do is start clean. Just like we talked about with managing Horseweed. Again, we're going to either use tillage or an effective burndown herbicide, and those burndown herbicides need to be effective on the waterhemp plant and also...will not be- and would have to have a site of action that's going to control it. With our burndown, we're going to want to make sure that we're using a soil-applied herbicide for residual or pre-emergence herbicide. Or if we're using tillage, we still need to use a PRE, because those PREs are going to be essential for control of both waterhemp and, when we've talked about before, Palmer amaranth. For those PREs, we need to be using the fullest rate we can for the soil type and organic matter, so, on some of our sandier soils, we might be using less of a rate. But again, we need to match up those rates for those soil types. The herbicides that we've had the most luck with for controlling glyphosate and ALS resistant waterhemp have been the group fourteen herbicides; either the Valor flumioxazin premixes, or anything that would have sulfentrazone; again, there's those Authority products. And we need to be making sure that we have high enough use rates. We can also use metribuzin to improve control, but in general, metribuzin by itself is probably not going to be the most effective. We've also had good control with some of our group fifteen herbicides; these are things like Dual, Warrant, Outlook and Zidua. However, one of the ways we might want to use these group fourteen herbicides is to maybe give us some residual control with our later post-emergence applications. So we can tank-mix these herbicides with some of the things that will control post-emergence; for example, Flexstar, Cobra, and then that would provide us some residual control later in the season for some of those later emerging weeds, so. That's potentially where you might want to use one of those herbicides. Again, with some of our pre-herbicides we can see some soybean injury. Just to be aware of that, and many times that soybean injury, those plants can outgrow that, and we most of the time do not see a yield loss. As far as with those pre-herbicides, we also need to follow up with timely post-emergence applications. Our POST products- we know we need to be making those before the waterhemp plants reach three inches tall. As those waterhemp plants and- get larger in size, they're harder to control. In RoundUp Ready soybeans, again, all we have are the group fourteen herbicides; things like Flexstar, Cobra, and Ultra Blazer to control emerged waterhemp in with those resistance issues. Again, if we're in LibertyLink soybeans, we also have the option of including Liberty. And we want to make sure we're using a minimum rate of twenty nine ounces. And since all these herbicides are contact herbicides, we need to make sure that spray coverage is important and a minimum of fifteen gallons per acre needs to be used. As I mentioned before, the group fifteen herbicides work well from a residual standpoint. And in many cases, we might want to add those with that post-emergence herbicide to help ma- get us through the rest of season because many of those waterhemp and Palmer amaranth plants can emerge later throughout the season. And, also, keep in mind, those group fourteen- fifteen herbicides; the Duals, Warrants, Outlooks, Ziduas, are not going to control emerged plants. So that's where that tank mixture is important, whether it's with a Flexstar, a Cobra, in RoundUp Ready soybeans; or potentially with Liberty in LibertyLink soybeans. There are some premixtures that are out there on the market that contain both the group fourteen and fifteen herbicides, and those are Prefix and Warrant Ultra, so again, those are potential products that could be applied post-emergence to get us that...control the emerged plants as well as give us some residual control later in the season. In many cases we're going to get good control of watehemp; have to follow these additional steps. But, again, we do not want these resistant plants to spread. And in some cases if those residuals aren't working well, an additional POST application might be needed. Again, the important thing is to make sure that you're not exceeding any maximum seasonal product's rates, particularly with things like Flexstar, so if we're using Flexstar in RoundUp Ready soybeans, we may need to come back with Cobra, or we may need to come back with something like Ultra Blazer. And again, the size of those plants are going to be very important. Probably one of the things that most people don't want to hear, but in general, we want to make sure that these plants are not producing seed, so we want to get them out of the field. So if it's possible, it's important to remove plants prior to seed set, and again, those female plants are the only ones that are going to be producing seed. If those seed heads are present, if the seed is present on those seed heads, you wanna make sure you remove those plants from the field and destroy 'em; many people move ' take ' out of the field and burn them to help destroy those plants. Another option is if you have a small area in the field, try to harvest around that area so you're not dragging your combine through that area and spreading that seed all over. Or if it is...or if you need to harvest through that area, try to harvest those fields last. Again, very small seed can be transferred fairly easily with a lot of equipment, so we're just trying to make sure that we're not getting the spread of these resistant weeds. Another thing I want to warn you about, as I mentioned before, many of the options that we're looking at rely very heavily on those group fourteen herbicides. And that's why we really suggest in the areas where waterhemp or Palmer amaranth are a major issue to look at using a potentially look at using LibertyLink soybeans. Because the group fourteen herbicides...there has been resistance developed, particularly in waterhemp, in some of the states, and it's pretty widespread. Particularly in Illinois, many waterhemp populations have resistance to the group fourteen herbicides in addition to glyphosate resistance and ALS resistance. And there are a few populations that actually have resistance to four different herbicide sites of action groups, so this is a population that's Illinois ALS resistance, atrazine resistance, glyphosate resistance, and also resistance to things like Flexstar and Cobra. And, right now they also have a population that has five-way resistance. And, in particular, 2,4-D and also the HPPD inhibitors, so, again, just more resistance. These- the waterhemp plants, as well as Palmer amaranth, because of that genetic diversity that we see, we do see expanded resistance that keeps showing up. As far as corn, we want to follow the same steps. And I'll just mention that we're really looking at trying to look at two effective herbicide site of action groups. And I want to mention that we do have a fact sheet that I'll put up in a minute that gives you some example programs that will potentially work for controlling the multiple resistant waterhemp that we're seeing in Michigan, so. Gives us some, just, suggestions; these are not the only programs that'll work, but it does give you a good idea of types of strategies that you can use, and really focusing on trying to use multiple herbicide site of action groups that are effective at controlling waterhemp. So with that, I'll, I'll show you this fact; again, this is in the back of our Weed Control Guide or it can also be found at Really talks about telling the differences between Palmer amaranth and waterhemp; some of the identifying characteristics. Really walks you through some of the steps for management in soybeans, and a lot of this is from our research that was funded from the Michigan Soybean Promotion Committee, as well as some of the steps that we have for controlling these weeds in corn. And again, the Corn Marketing Program has helped fund some of that, so we've got some really good programs to help manage some of these resistant weeds. And as you can see here, we have our website, The fact sheets can be found there as well as the MSU Weed Control Guide. So it looks like we've got a, maybe a minute or two for questions, and I think I'll go ahead and I'll turn this back over to James us move forward with that. >> Speaker 1: OK. I want to say one last thank you to Christy for tonight's information; I really appreciate her joining us for this evening and for participating in the series. I guess with that I will say good night. And hopefully everyone will join us next Monday for the second webinar in our series, and be looking for a minor email about that.

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