Announcer: The following presentation
is part of the Agronomy and Horticulture Seminar Series
at the University of Nebraska-Lincoln.
-: All right, well, good afternoon, everyone.
Welcome to the Agronomy and Horticulture
Friday seminar series.
I can see from the list of attendees
we have a few folks from Wisconsin on, so welcome.
As you can see from my background,
we've kinda had a heat wave down here in Nebraska,
so I hope you're staying warm up north.
All right, today's seminar is gonna be presented
by Dr. Nevin Lawrence, and I'll introduce his title
here in a second, but just a little about Nevin
and his background, so he did his undergraduate
and master's work in Wyoming,
but he worked with Dr. Andrew Kniss and Dr. Bob Wilson
for his master's degree.
And so he's already had a little bit of interaction
with Nebraska, even back in his master's work
with Bob Wilson in the panhandle
and then across state lines over into Wyoming.
And then he and I have talked since he's been here
and realized that we missed each other
by about a year out in Pullman.
So he went to Pullman in 2011 to start work on his PhD
and graduated from Washington State University in 2015,
and then he joined the faculty here at UNL
at the Panhandle Research and Extension Center
in January 2016, and he's a integrated weed management
specialist there in the western part of our state.
And so I know he's gonna talk a little bit
about some of his research out in the panhandle
and some of the work he's been doing
over the last five years that he's been here,
yeah, five years that he's been here in this role,
but his title today of his presentation
is Management of Herbicide-Resistant
Palmer Amaranth in Minor and Specialty Crops
within the High Plains.
We'll hold the questions until the end of the time here,
and then we'll set aside some time for Nevin
to address any questions you might have.
But for now, Nevin, whenever you're ready, go ahead.
-: Thanks, thanks, Chris.
You know, after the crop production clinics
and the Nebraska crop management conferences,
I think this is the fifth time this month
I've had the pleasure of being introduced by Chris on Zoom.
So thank you, Chris, and thanks for all your work
for those online extension events.
So if I had to kinda point out what I've been doing at the,
in my position in the panhandle these past five years,
I could really break down my projects
into three broad categories, kochia germination ecology,
and that bottom picture is actually
one of our larger studies we've done on this,
and you can see some of the kochia start to come up.
This is taken in April. I won't be talking about that.
And then on the right,
I've got a photo of some rubber dandelion.
This is a species of dandelion native to Eurasia
that we're trying to domesticate
to make a domestic source of rubber.
And I also won't be talking about that,
but just some other things I'm working on.
And I will be talking about, a lot of the work
I've been doing has been on Palmer amaranth,
and I'm gonna focus on that because that lets me focus
more on the graduate students
that have been working in my lab,
which I couldn't really get anywhere without them.
So Palmer amaranth is a species
that if you're in the Midwest or the South
or in Nebraska, you've heard a lot about,
but it is sort of a new thing for the panhandle.
And so Palmer amaranth, here's a photo of some borders
of some plots I had where I just didn't spray
outside the research plots, and so we kinda got weedy
at the end of the year.
And this is Palmer that's been emerged since May,
and it's been competing season long in the corn.
So in this photo, it's about seven feet tall
by the end of the season.
And that photo in the front of the plots,
in front of the corn there, you can see some Palmer
that's emerged later on in the season.
And if you walk into the corn
about two, three meters in there,
you actually go into where the plots were,
and those plots were weed free from May,
really good weed control, all the way up
through about early September.
And then when early September occurred,
the corn plant starts to senesce, the leaves fall off.
Some sunlight comes to the rows,
and sure enough, that's enough to trigger
a weed emergence all the way at about September 15th.
Not a lotta seeds can be produced.
This will have zero impact on yield,
but you're contributing seed to the seed bank.
So this is a weed that we're controlling
from as early as late April all the way through September.
It really is a season-long weed in all of our row crops.
And it's a prolific seed producer.
So this is one of my favorite images in weed science.
This is by Jason Norsworthy and others out of Arkansas,
and it's a glyphosate-resistant cotton crop
where they sprayed glyphosate.
Some of the Palmer didn't die,
so they just kept spraying glyphosate,
and then they harvested the cotton crop.
And what you see is a picture from 2008
where they had that initial flush,
and then the picture on the right,
you can see just how much seed was spread
throughout that field in one year.
So it's something that can be pretty explosive
in its populations.
It's also a very adapted species for developing resistance.
And so you can see on the list here, Amaranthus palmeri
is kind of in the middle down there with,
and this is of 2019, seven separate
herbicide site of actions,
so the part of the plant's physiology
those herbicides are targeting
have been found resistant in this species,
and some populations of Palmer amaranth
has as many as five simultaneous resistances.
So it's very adapted to herbicide systems.
Palmer amaranth is native to sort of the US-Mexico border.
It's a desert species, very adapted to dry conditions.
And from that area, it's sort of moved into cotton,
and it's been a long-time weed in the Cotton Belt.
And it wasn't always a problem.
It started becoming a problem when production
moved to glyphosate-resistant cotton,
and then they're rotating that
with glyphosate-resistant soybeans
or glyphosate-resistant corn,
and you're using glyphosate every single year,
and eventually resistance happens.
And it's since spread, originally they think
in a cottonseed lint which was fed
to feedlots as cattle feed.
The cows produced manure.
The seed happily survives,
so that manure gets spread on corn fields,
and the circle of life continues.
So when I started my position in Scottsbluff in 2016,
this is sorta the extent of where Palmer amaranth was.
And when you look at where I'm located,
I do research in the panhandle of Nebraska,
mostly centered around this irrigated acres
around the North Platte here in Scottsbluff.
And Palmer is a fairly recent arrival
kind of moving up the North Platte in the northwest,
in a northwesterly direction towards Wyoming.
And the real kind of what I call the Bermuda Triangle
of Palmer right now, where I'm at is
between Bayard, Alliance, and Bridgeport.
It's very heavy, and it's been moving
further and further each year.
So when I started in 2016,
we found it as far as Mitchell, Nebraska,
and then in 2017, we started seeing it in Wyoming.
So by the time I was in my second year here
at the University of Nebraska,
at least Southeast Wyoming was also a new arrival.
So one of the ways I could introduce myself is to tell you
that I'm one of the top six dry bean and sugarbeet
weed scientists in the entire country.
And the reason I'm not bragging about that
is there's six of us, and where there are dry beans grown,
there's also sugarbeets grown.
There's real no economic or agronomic reason for that.
It's just the people that settled these areas
tended to grow both crops.
sugarbeets tend to be grown in parts of the country
where soybeans might not be viable but dry beans are.
So I'm one of six, the small group,
but we both work in the, we all of us work in these crops.
And I'm kind of in a unique situation.
So when we look at these six growing regions,
the three main weed species I'm dealing with,
because of resistance, are kochia, waterhemp, and Palmer.
And kochia is a problem for myself and Nebraska,
folks in Colorado, Wyoming, Montana, and Idaho,
but it's not an issue along the Red River Valley
in North Dakota and Minnesota, or in Michigan.
They're not, they don't deal with kochia.
When we talk about waterhemp, I've got an issue with that.
So do my colleagues in North Dakota
and Minnesota and also Michigan.
But when we look at Palmer amaranth,
it's really not widespread in Wyoming right now.
My colleague Andrew Kniss the University of Wyoming
doesn't have it on his research plots.
He can't find a large enough population to work with it.
So it's really just me and Christy Sprague
in Michigan that are working on Palmer amaranth,
but it's hard to collaborate so much with her
because of some differences in climate.
And even, so when I'm trying to research this pest
and specifically in these crops,
I'm really the only researcher that has been
starting off researching this and coming up
with solutions to these projects.
And that's a plus because there's a lotta things I can do
that no one else has, but it also limits my ability
to collaborate with peers, at least in these crops.
I have other things going on in soybeans, sunflowers,
alfalfa, but specifically with dry beans and sugarbeets,
I feel a little bit like I'm on my own with what's going on.
And part of this where the weed is,
but also the environment.
So I like to describe my program
as Midwest Weeds in a Mountain West Climate.
If you were to look at other parts
of the country that grow similar crops,
similar rotations, have similar climate,
I'm very similar to actually my colleague in Southern Idaho,
but I've got weed species he's not dealing with.
And it's beyond just the Amaranthus species,
waterhemp, and Palmer amaranth.
I'm also dealing with marestail and a few other weeds
that just aren't found further west from where I'm at.
And where I'm at, we also have unique soils
and unique weather events that limit
some of our herbicide options.
And this is an image that I show
in almost all my extension talks
to kind of show the situation we're facing.
But when we talk about herbicide resistance
in the panhandle, we've got a lotta options on corn.
We can handle just about any resistance
that shows up currently in our area.
But when we start moving into corn
before dry beans or sugarbeets, we start to get limited.
A lot of our growers are just using dicamba
and glyphosate in corn before sugarbeets
because that's what they know is effective,
and there's not much else.
If they're lucky, then maybe they'll throw in
a group 15 herbicide, but when we start to get
into dry edible beans, we have good pre options for control,
glyphosate and ALS-resistant Palmer amaranth,
but we only have Reflex, and there's an asterisk on there,
I'll get to that later, and that's it for post options.
For sugarbeets, we have no herbicides right now
that work for Palmer amaranth control at all.
So part of that is climate, and part of that's the crops.
So compared to my colleagues in North Dakota,
Minnesota, and also in Michigan,
they have two additional herbicide mode of actions
available in dry edible beans and one additional one
in sugarbeets that dramatically change
how they approach combating this weed
that I just don't have access to
because of crop safety issues because of our soil type.
So as I've said, I've been here since 2016,
and as Chris alluded to, I actually did some
of my master's work in Scottsbluff in 2011.
So here's a photo from Scottsbluff, 2011,
and that poor guy in his hands and knees
counting weeds is me, and each one of these flags
we've put a quadrant on and did a weed count.
This is about a three-acre field.
This took about, I think, two days,
maybe three days to count all these.
But at the end of the day, I had a very good sense
of what weed species were present
at the Scottsbluff research farm.
And when I took this job in 2016,
you know, I did my homework.
I called crop consultants. I called commodity groups.
I tried to get an understanding
of what issues they were dealing with.
And one of the things that did not come up very often
or not at all actually was Palmer amaranth.
Kochia really was the, what they were focused on.
And so before I started my job in January 2016,
in December 2015, I submitted my first two grants.
That was to the Dry Bean Commission
and Western Sugar Cooperative.
And these were both focused on the management
of glyphosate-resistant kochia
because I just was not expecting to have Palmer amaranth.
And I remember talking to the technician
who has since retired, who had been with Bob Wilson
for a few decades before I got there, you know,
"Where can I put these trials out
to get a good population of kochia?"
And her answer was that, you know,
anywhere I put it, we're gonna have a pretty good stand.
So this is the first trial I put out in 2016
for sugarbeets, and there's the kochia population there.
And if you're not too good at weed ID,
that's nothing but Palmer amaranth.
Similarly, here's my dry bean trial looking at kochia.
And once again, it was also Palmer amaranth.
So I was really caught off guard this first year,
and it went from a little bit of a panic
about you know, these trials aren't gonna go well
because I'm not targeting the weed I said I was going to
to realizing that this wasn't just a problem for me.
This was really the first year this weed
was blowing up in the panhandle.
It had been in the background.
No one was really paying attention to it,
but 2016 was the year all the problems started.
So I'm gonna focus, I got a lot I could talk about,
but just for the sake of brevity, I'm gonna focus
on the three graduate students that have been
in my program and are currently in my program
and the projects they're working on
to tackle Palmer amaranth.
And these projects, usually each of their chapters
was funded by a specific grant
to one of the commodity groups in the state.
And we'll just walk through what they've been up to
to kind of you a sense of what I've been doing
from the research standpoint.
And the first one I'm gonna talk about
is this grant I submitted in 2016
on managing glyphosate-resistant kochia in dry beans.
And the idea of this is dry beans are one
of our better rotational crops to manage kochia,
and the reason for that is they don't overlap very much.
So when kochia is kind of at the tail end of germination,
dry beans are at the beginning of their emergence.
And so if we just push off the dry bean planting
maybe a week, we pretty much avoid kochia,
and that was the idea behind this.
And so in dry edible beans,
we have pretty much two herbicides systems that are used.
We have those that gravity irrigate,
who are having to put in furrows and flood their fields,
and they use a, what we consider PPI herbicides.
So these are something like Eptam and ethalfluralin
that are very volatile.
They spray that in the field.
They're gonna stir that soil up
to prevent the volatilization, and those,
the people that are doing the gravity irrigating,
they're gonna be using those PPI herbicides.
And then we have other farmers
that are under a center pivot,
and a lot of these have moved to no-till production systems,
and they won't be using these PPI systems.
They'll be using something like pendimethalin
plus dimethenamid-p or Prowl plus Outlook pre-emergence.
And then they'll usually both these systems come back in
with something like a Raptor and Basagran post-emergence.
And so I was trying to do this with kochia
and ended up with a entire population of Palmer amaranth,
but we actually noticed something from this trial,
And this is the 2017 data, we did this a few years,
but with the 2017 when this PPI treatment was used,
we saw no Palmer pressure at all from this late planting.
So when we delayed planting a week,
we saw no Palmer amaranth, and this was kind of considered
maybe it was just luck, but we repeated this in 2018 again,
and we saw the same thing with the PPI treatments
that the late planting date,
we just weren't seeing any Palmer pressure.
But also with these pre-treatments, too,
so the Prowl plus Outlook treatments,
when we delayed that planting,
we're actually seeing less Palmer.
And so moving the planting date back just a week or so
was delaying, was better lining up
when these soil-active herbicides were in the soil
and preventing emergence from dry edible beans.
And so one of the initial recommendations I can make
to growers was if you've got multiple fields
and one of 'em it seems to be a bit heavier
with the Palmer pressure, actually moving the planting date
back a bit and planting that field later
may help with better control, and this has been seen
with a few other species in the literature.
And we also found out that the Eptam plus,
the PPI treatments, probably because the tillage
but maybe also the nature of those herbicides,
was providing pretty phenomenal control.
A lotta times we can get by with season-long weed control
of Palmer amaranth without any post herbicides,
which is good because the Palmer amaranth
is fairly limited, or the post-emergence options
in sugar and dry beans are fairly limited.
And we also weren't seeing really an impact on yield
by delaying that planting, which was another good benefit.
So the other project that Clint was working on
that we just got published in "Weed Technology"
is this product called Betamix.
So before glyphosate sugarbeets were a thing,
there was this product that we used
for Amaranthus species called Betamix,
and it's a 50/50 mixture of desmedipham and phenmedipham,
which most of the weed scientists on this Zoom meeting
probably had never heard of, and the reason for that,
it was only labeled in spinach and beets,
so very narrow market share.
And the way these products worked
is if you were to apply a full rate to small beets,
you'd completely kill your beets,
and so you couldn't do that.
So instead, they developed this thing
called a micro-rate system where you would spray
a low dose of Betamix every seven to 10 days,
and what ended up happening is this picture on the right.
You've got quite a bit of photosystem II injury,
some smaller beets, quite a bit of yellowing on the beets,
and a lotta farmers refer to this
as chemotherapy for the beets.
So it was gonna kill the weeds,
but you were gonna see some yield impacts
from adopting this system, and you did.
It was quite a bit of injury, and it was time intensive,
and sometimes it just didn't work very well.
So once glyphosate-resistant beets were, came out,
no one used Betamix anymore.
Bayer decided not to extend the registration of it,
and you can no longer buy this product in the United States.
Once again, though, as I've said earlier,
there are no options right now for management
of glyphosate-resistant Palmer amaranth in sugarbeets.
So what do you do?
Well, a lot of farmers still have
quite a bit of Betamix laying around.
It's been laying around for a number of years,
and what they did is they were trying to use it
as a rescue treatment.
So in 2017, I started getting calls
from different farmers saying, you know,
"Can we use Betamix as a rescue treatment?
What rates should we do?"
And usually I got these calls,
the situation was, they sprayed glyphosate.
They noticed it wasn't working maybe a week later,
so they sprayed it again, and then a week later,
they might go out and try the Betamix.
And Betamix, when it was sprayed in this micro-rate system,
went out with clopyralid and ethofumesate,
two other herbicides.
And at maximum, the labeled rate was three pints an acre,
and that was labeled for two-inch-tall Amaranthus species,
and some of these farmers were applying eight pints,
a full gallon of the product,
which is just a ridiculous amount,
and this was being applied to weeds
that were over a foot tall.
And so what we're seeing, and this is a picture
from an actual field where this eight-pint rate went out
with, I wanna say, a half-gallon
of glyphosate at the same time.
So here's a Palmer amaranth plant
that's showing some epinasty from the clopyralid
in the mix, not enough to kill it though.
This plant eventually came out of it.
Here's another photo of photosystem II injury
from the same field.
This is one from the desmedipham-phenmedipham
at that very high rate, still not enough
to actually kill the Palmer amaranth plant,
and it once again was able to come out of the injury.
And then from the same field just a few feet over,
here's a picture of some Palmer amaranth plants
that look pretty uninjured.
They came outta that really well, and what you see instead
is some injury to the sugarbeets,
and so this just clearly wasn't working.
And so the question I was being asked is, you know,
"How high of rate do we need to go?"
And I think the issue wasn't how high of a rate
they were using, it was how big were these weeds.
And at the same time as we're trying to figure this out,
I do have the colleagues in other parts of the country
that were really pushing for the reregistration
of Betamix to get another tool in the toolbox,
which honestly just wasn't working good from my perspective.
So we did some work on what size that we need to target.
And so here's Betamix at a bunch of different rates,
these treatments one through four,
and the zero on this graph refers
to Palmer amaranth that had just emerged.
So cotyledon-sized Palmer amaranth, and then we sprayed
four, seven, 15, 20, and 28 days later.
And then this is two weeks after the application date,
we harvested those Palmer plants and took biomass.
So this is the biomass
grams per meter squared on the left.
And one thing that you'll find out
in introductory statistics is when your error bars
are twice the size of your means, you didn't do anything.
So there was really no difference from the Betamix.
Even when we sprayed it at a full rate
at the cotyledon-sized beets,
we just weren't getting any control.
So we decided to take this project in the greenhouse,
and we were trying to calculate
what's called a selectivity index,
which is what rate gets 90% control of a weed
but only 10% injury or death to the crop.
And so if you can get that ratio,
there's a chance for selectivity.
So this is the desmedipham component
doing a full-dose response,
the phenmedipham component in a full-dose response,
and then the Betamix products together.
And then on the y-axis, we have the percent survival,
and then on the x-axis we have the rates.
And what we saw was when we sprayed two-true-leaf sugarbeets
and we had cotyledon-sized Palmer amaranth,
this full rate, the 1x rate of Betamix
was getting 0% survival from the Palmer amaranth,
but we were having 100% survival of the sugarbeets,
so it actually looked like it was working
as according to the label.
But when we waited till four-true-leaf beets,
when the Palmer amaranth at this point had grown
to seven inches tall, for us to get a good control,
so 0% survival and about 90% survival in the sugarbeets,
we were now approaching a 4x rate,
or in this case, we were applying 1 1/2 gallons
of Betamix, which is just,
if this product was ever re-registered,
is completely uneconomical and just an insane amount
of product to be putting out.
And with that survival,
we're seeing quite a bit of injury.
And so this just kind of told me that,
you know, unless the growers can get after it
really early in the year, which for the most part
they weren't able to do, this product's just not gonna work
as a rescue option.
And so it was sorta bad news in a way,
because I don't really have an alternative
for the sugarbeet growers, but it wasn't worth their time
pursuing that re-registration or trying to figure out
how many gallons of product to put out
to get the control, because it wasn't working.
Going back over to dry beans,
a third project that Clint was,
has since finished, is on Reflex.
So this is the only product we have
in Palmer amaranth for post-emergence, and it works great.
I've done a number of projects with Reflex.
It's the best product that was available
in dry edible deans, and really can't say enough about it.
It has a little bit residual,
controls the Palmer amaranth,
but I started getting questions about this thing
called the North Dakota program,
and this is from a number of growers that contacted me
in Nebraska and also Colorado.
And this is a screenshot from the North Dakota weed guide
or their weed control guide,
and what they're recommending
is using a micro-rate system for Reflex
along with Raptor and Basagran at reduced rates.
And so they're actually cutting that Reflex rate
by about a third and recommending to, in the Raptor rate,
by about 1/4 and the Basagran rate by about half
and recommending spraying it every seven to 10 days.
And when I started getting questions about this,
it really just didn't make a lotta sense.
Usually we try to recommend against these
in micro rates because they,
you have a bigger, a better chance of the weed surviving it.
There's a potential for what we call
kind of resistance drift
where you're able to survive a small rate
that maybe a higher rate would've killed the plant,
and so over time, you can develop,
have a better chance of developing resistance.
And it just requires more trips to the field
and it complicates the weed control program
because it's something that's not even found
at the label, and it puts the grower
at their own risk for applying this.
And when I called the weed scientist
who developed this program, it turned out they had never
actually tested it on Palmer or waterhemp.
What they had done instead is bought a bunch
of ornamental Amaranthus species,
planted 'em out in the field
and tried this, and it seemed to work.
And so they thought this might be
a better option because you get two
application opportunities rather than one.
So we went ahead and tested that.
So if you're not a weed scientist,
don't pay too much attention to this table here.
But basically at the top,
we have every single legal application
and combination I can think of
of imazamox or Raptor, bentazon or Basagran,
and fomesafen or Reflex.
So that's everything that's labeled
that you could you could possibly wanna do as a grower.
And then we had the micro-rate as a one-pass and a two-pass,
which was recommended, and then we threw in
a three-passe just to see if that made any difference.
And what we found is not a lotta difference.
So the photo on the left here is non-treated.
We have the standard rate of fomesafen
of the two-pass and the three-pass,
and there really isn't a whole bunch of visual difference
between just using the standard rate
versus these micro-rate programs.
These photos look pretty ugly, and that's because we,
this is without using a pre-emergent herbicide,
which you normally wouldn't do.
But if you go to the back end of these plots,
we actually had a strip-plot design
where the backend had those pre rates.
And when we apply those pre rates,
we had pretty good control.
So this is weed density, all these different treatments,
and basically when we didn't use fomesafen,
our density was about 45 plants per meter squared.
But when we used fomesafen, we dropped that down
to about 25, and it didn't really matter
if we had a full rate of fomesafen
with a pre-emergent herbicide
or for doing these micro-rate projects,
we just weren't seeing a big difference.
And so as long as Reflex was included,
control was pretty good, and we weren't seeing
a benefit from this micro-rate rate.
So this is something that we've been recommending
to growers is to stop doing that.
Just go do what the label says, use the full rate.
It's less passes, it's less complicated,
and it's probably gonna save you some money.
And this was recommended up until this year
because Syngenta has since pulled the label
for dry beans in our area, and this is no longer an option.
And so going back to this graph,
we don't have any post-emergent herbicide options
right now in Nebraska for Palmer control.
So what do we do?
And so I'm gonna transition away from Clint Beiermann
into Joshua Miranda, who is working on a problem
of sequential applications of Outlook.
And so this isn't anything that's new.
This is a concept that's been done in a lot of other crops
but with soil-applied herbicides.
You put 'em out early in the year at planting,
and they prevent weeds from emerging in that field.
And as those seeds germinate,
the herbicides control it, but eventually that herbicide
wears off, and you have emergence.
And then you follow up those emerged weeds
with a post-emergent herbicide.
But we don't have posts,
so what we do instead is we look to overlap
that soil-applied herbicide with another application
of soil-applied herbicides as a post-emergence
application to extend that control later on in the season.
And what we have available to us
and dry edible beans is the group 15 herbicides,
and specifically all we have is Outlook.
So commonly in our area, in the panhandle,
in corn and in sugarbeets,
we have post-emergence, not pre-emergence.
There's Dual, Outlook, Zidua, Warrant,
but as something, only Dual and outlook are labeled
for pre-emergence use, or labeled at all in dry beans,
and Outlook is the only one labeled
for post-emergence applications.
So we looked at this in 2019 and 2020,
and what we found is on the left here, we have the pre only,
so that was a pre-application of herbicides,
and eventually that failed.
You could see this August or this July 22nd picture,
there's some Palmer coming up.
By August 2nd, it's pretty bad.
But when we applied Reflex, which is our,
kind of our standard herbicide
prior to the label being pulled,
we can see pretty good weed control season long.
And this first trifoliate application of Outlook
did provide in 2019 season-long weed control of Palmer.
When we applied this, though, at the third trifoliate,
we see that there was a complete breakdown in that system.
The Palmer was able to emerge through there,
and we're not really seeing a big difference
between the Outlook at third trifoliate
and the pre-emergent only.
So in 2019, the timing of this program
was critically important.
And then in 2020, what we found out
is both applications' timings worked,
so it's different from year to year.
We still haven't had that nailed down,
but the first trifoliate application
seems to be consistently good.
And that third trifoliate isn't working as well,
at least in 2019.
So the other thing we're trying to do, though,
is expand the use of group 15.
So we have Dual II Magnum that we also tested this year.
So this is a pre application, only Dual II Magnum,
compared to Outlook and also with Zidua.
And then we followed it up with a sequential application.
So Outlook followed by Zidua,
Dual Magnum followed by Dual II Magnum,
and then Zidua followed by Zidua
and then compared that to a treatment consisting of Reflex.
And what we found in 2020 is these products
actually all looked pretty good.
So we saw from the pre-emergent-only treatments
a reduction in biomass compared to the non-treated check,
and in the sequential programs, the control was as good
as if we included Reflex.
And so this data has already been submitted
to the NDA and also with Syngenta
to help them in getting that Dual Magnum,
Dual II Magnum label updated.
It looks like it's gonna be the Dual Magnum labeled,
so the Dual II Magnum, it's very subtle difference,
not very important, but we,
this will be registered if not in 2021 in 2022.
So this is already paying some dividends
from one year of data.
But with the Zidua, we actually saw
some pretty severe crop injury.
However, that crop injury appears to be related
to that pre use of the product.
In the post use the product alone,
you probably wouldn't see this, and that's something
that BASF is currently pursuing as well.
The other thing that Joshua has been working on
is looking at Palmer interference in dry beans.
So what is the impact of Palmer amaranth?
Can we quantify that?
And what can we tell growers if they call us up
with a weed control failure?
So what he did is we waited
till Palmer emerged in a dry bean field.
This is naturally occurring population.
And then Josh went out, Joshua went out with zip ties
and zip-tied a bunch of plants at known densities.
And then two to three times a week
for the rest of the summer, he went out with a hoe
and removed every other plant,
and we were able to maintain these densities season long.
And so from this, we can calculate how much Palmer density
relates to how much dry bean yield loss.
And so this just started this year.
We'll likely, we are gonna need another year of data
next year to provide some, a bit more substantial data.
But what we are seeing is the yield loss
in dry edible beans is greater than what's been reported
in corn, soybeans, and peanuts.
So dry beans seem to be more susceptible
to Palmer interference than those other crops,
and from, we're estimating about a 50% yield loss
is occurring at about a Palmer plant per 0.37 meters a row.
And so that's saying one Palmer plant for about nine feet
a row is equaling about a 50% loss in yield.
And we can also quantify seed production from this as well.
So we counted the number of seeds or weighed the number
of seeds produced per plant, and you know,
one plant every every two meters is equaling
about 60,000 seeds per meter squared.
So extrapolating that off to a full hectare of,
or acre of crop, and you know,
you're up in the tens of millions.
Lastly, Whitney Frazier, who's been with me
for quite a while, she's getting her graduate degree online
while working as my technician,
has done the same thing with sugarbeets.
And so we've been quantifying the yield loss
in sugarbeets, and for how bad it is in dry edible beans,
it's actually worse in sugarbeets.
So we're seeing, at least in 2018,
one Palmer plant per two meters of row
was equaling about 89% yield loss,
which is far exceeding anything
in the literature for other crops.
However, in 2019, where the Palmer emerged a bit later
in the season, that yield loss is closer to about 40%.
And once again, she's also quantifying the seed production.
If you notice here, the higher densities there,
we only that in 2018, and the reason for that
is the yield loss was so severe,
we had to go back and readjust our rates
and our densities in this treatment.
And this information, we actually just submitted
to the Nebraska Department of Ag as well,
because we're pursuing an emergency-use label
for a soybean herbicide for use in sugarbeets
that hopefully might be used as a rescue treatment
when growers are facing this
because they currently don't have anything.
So this is some of the information we're using
to justify that new label expansion.
So that's the research I've been doing.
I'm also gonna finish this off really quickly
by talking about some of the extension work
I've been doing in Palmer amaranth.
And as I said before, 2016 was a real surprise to me.
I didn't think I'd be doing
this much work in Palmer, if any,
and it turned out that's kind of what my program
has mostly been focused on.
And the same year that I started and this happened
is the same year that all of the Western Nebraska
was sort of going through this kind of Palmer emergency.
And so in 2016, I had over 70 pigweed samples
brought to my office, and this was, I think I,
there was days I miss, I had to miss people,
so this count's probably higher,
but it was at least 50 separate visits.
I had sometimes three or four people coming per day
to say, you know, "Is this Palmer?"
You know, "What happened?"
And we were finding a lotta redroot,
some waterhemp, and some Palmer.
Most of what was brought to my office
wasn't Palmer amaranth, but clearly they were having
trouble identifying this.
If it was Palmer amaranth, we would take that sample
and send it off to Prashant Jha at Montana State,
he's now at Illinois, and he would help
to do some molecular ID of what resistances
might or may not be present.
But clearly they were having trouble with this.
So in 2017, some of the groups that were coming
to my office more often were Western Sugar Coop,
Panhandle Coop, and Westco.
And I called 'em up and said, "Let's just have a day,
and we're gonna work on Palmer ID."
And I couldn't find a date that worked,
so we actually had five separate events,
brought in about 50 people in total.
And these are agronomists that are each servicing,
you know, several hundred acres each,
and we just went through Palmer ID,
and they all left with this thing on the right here,
which was a laminated handout I gave to 'em
to kind of help them in their truck
understand what's going on.
And we also went through some of my herbicide plots
where I could replicate this is a weed escape,
this is a case of resistance, you know,
let 'em know what that looks like in the field.
And in 2017, we went down from 70 samples to 20 samples.
And then from 2018 to 2020,
I've had less than five each year.
So this is one of the more successful things I've done,
and it was pretty informal, but it was definitely needed.
So there was just a real big misunderstanding
of what Palmer and redroot and waterhemp looked like
when I first began my position.
This next thing I'll talk about
is sort of a longer-term project.
But in 2018, Andrew Kniss and myself,
we held this resistance workshop, and it was funded a,
and Andrew Kniss from University of Wyoming,
funded by a USDA NIFA grant we were on.
And the idea was to help growers manage resistance
or prevent resistance, and mostly targeted
to agronomists, but we had some growers there as well.
And so the way I try to explain herbicide resistance
to farmers is actually I start with this image,
and this is from a textbook,
an agronomy textbook from the 1950s.
And just briefly, these black bars you see
are the time of the year
that a particular crop has canopy closure.
And so at that point in the year,
sunlight's not reaching the soil,
and the weed germination is less.
And so when we talk about weed control,
we're usually talking about from planting
through canopy closure, and that's the goal of weed control
is to get those weeks and months controlled.
These little arrows refer to cultivation,
and these circles refer to tillage.
And so on the left here, we have a corn, soybean,
corn, soybean rotation.
And on the right here, we have corn, soybean,
then we move to an oat/forage legume, so probably alfalfa,
and then the fourth year, it's just alfalfa.
And then these little star things refer to when
the swath has moved into the field to cut the alfalfa,
which is also a form of weed control.
So you look at these two systems,
and what do you see over four years?
We're doing a lot of the same thing over and over
and over again in the corn and soybean rotation.
When we add a little bit more diversity to the program,
we're spreading out these disturbances,
we're spreading out the biology
of when the crops are competitive
when we're cutting a crop down.
And this is the same way that herbicide resistance works.
So weeds adopt to the cropping system
they find themselves in
regardless if there's herbicides or not.
So they can adopt to organic systems.
They can adopt to tillage systems.
They can adopt no-till systems.
And when you're doing the same practices
over and over and over again,
the weeds are going to adapt to that system.
And so when it comes to managing resistance,
we just need to add diversity to the field,
or to the system, and this is supported in the literature.
One of the things I like to cite is a study
by Evans in 2016 where they surveyed
I believe 106 farmers in Illinois,
and they looked if that farmer had herbicide resistance
and if they did what practices they were using.
And they found a lotta practices
didn't really influence herbicide resistance.
But one that helped was if they were mixing
two herbicide modes of action,
they were reducing their risk of herbicide resistance
by 83 times compared to if they're just using
the same herbicide mode of action in a given year.
If they use three modes of action,
they were reducing that risk by an additional 57 times.
So if they're using three modes of action,
they're 140 times less likely to have resistance.
So just use more herbicides and make your cropping systems
more diverse, and you'll do better.
And so how do we add diversity?
Well, we can add more crops to the system.
We can add tillage, we can add cover crops,
we can add more herbicides, but this all comes at a cost.
So we have markets to think about for adding crops.
More tillage or adding in cover crops
might require an equipment change or may lead to issues
of soil health or other pests potentially,
and adding more herbicides just costs more money.
And so this is actually kind of a hard situation
that growers have to deal with if they are concerned
about really anything in agriculture,
but specific to this example, managing resistance.
And then the bigger question is how do we effectively
mix herbicide mode of action or use more herbicide
modes of action when we don't have
more effective herbicide modes of action?
And the solution to this is in the rotation.
So when you can add more modes of action,
let's say in corn, you try to do that.
So what we did in this 2018 workshop
is we kind of explained this
in a pre-workshop seminar or a presentation
Then we had a post-workshop presentation
and tried to explain how all this works,
about how to manage this.
And what we did is we broke these participants
into several groups, and they were given
seven weed species, five crops.
So I got the weed species on the left.
We have the corn, wheat, sugarbeet, dry bean, and soybeans,
and then we gave 'em a copy of the Nebraska
Guide to Weed Management and told 'em to come up
with a herbicide program for a given rotation.
And they had to come up with one that was effective,
so it had to control the weeds,
it was economical, it had to, something they can afford,
and it had to use two effective modes of action,
herbicide modes of action for each weed.
And this wouldn't be too hard
for most of the weed scientists on the call to do,
but if you're not used to working in weed science,
this is really difficult.
And it took some of the participants
more than three hours to come up with a solution
just because it's something they don't do daily.
And the reviews of this, we got back the feedback,
they actually liked the management workshop.
It was helpful, it helped explain things,
but it was a pretty hard process
to be thinking about this over multiple years.
It took them a long time.
So what we decided to do is automate this.
And so we developed, and Andrew Kniss and myself
and then a colleague who used to work in Andrew's lab,
is now at University of Idaho,
developed an online calculator
just to automate this whole process.
And so what you do is you pick a weed of concern.
You enter in a four-year rotation.
You have to use a four-year rotation,
and then you pick an herbicide program.
And the calculator comes up with herbicide efficacy,
the risk of reducing, of producing resistance,
and then also the cost of the program.
And so to give you an example what this looks like,
we've got Palmer amaranth in the system,
and then we've got three resistances we picked,
so ALS resistance, photosystem II,
and glyphosate resistance.
Pretty common in Nebraska actually
to have those three resistances,
and then we pick our crop rotation.
So we got corn, corn, corn, and corn,
so you could pick the same crop all four years,
and then you add in your herbicides.
And so this case, we're just gonna spray
glyphosate and dicamba all four years,
and what we find is that's a pretty effective program.
It's a pretty low cost.
They're both generic products that we can get
at not a lotta money.
But we look at the risk scores,
so glyphosate, there is no risk score,
but dicamba is a 4, and that's the absolute maximum
risk score you can get with this calculator.
And the goal of it, if there is a goal,
is to have a risk factor less than 1.
And this is not a quantitative measure.
It's a qualitative measure using pretty simple math
just to kind of give a broad range
of what's your risk for resistance.
And the reason this is a 4 is because
if you're using an effective herbicide
without anything else being sprayed in a given year,
you get a score of 1, and doing that for four years
gives a score of 4.
So if we use the same example
but then add another product here, this is DiFlexx DUO,
so that's a tank mix of tembotrione and dicamba again.
So now we have the group 4 dicamba here, which is a 2.
We have the group 27 tembotrione, which is a 0.4.
We see that weed control stayed the same.
It's not any more effective.
Our cost went up, but our risk score went in half,
at least for dicamba, but not much lower.
And the reason for that is the dicamba
is a more effective product
at controlling Palmer than the tembotrione.
So we're saying that the more effective herbicide
is gonna be at a greater risk for developing resistance,
so we're gonna penalize that a little bit.
Looking at a bit more diverse program,
we can do a Verdict pre, so now we're moving
into pre-post program, which is something
most weed scientists recommend,
followed by Status post with glyphosate once again.
We're seeing that the group 4 herbicide,
in this case Status, still containing dicamba,
is still pretty high risk because the diflufenzopyr
that's mixed with it isn't a very effective
Palmer herbicide on its own.
But with the Verdict, where it's a mixture of a product
called Saflufenacil and dimethenamid-P,
both of those products are very effective
independently in Palmer control,
and so we have a very low risk factor for that.
And so they can play around with different herbicide options
and kind of figure out what works and what doesn't.
One of the, what happens, though,
if you actually have to have a diverse rotation,
so this is a really common rotation in my area,
corn, dry edible beans, corn, sugarbeets,
is trying to pick an effective herbicide program,
you're kinda forced to use a diverse herbicide program
because you can't use the same herbicide in the same crops.
And so this is an example of where all the risk scores
are below 1, and this would be an economically
affordable program for most growers in our area
depending on the rates they're using.
But we're seeing, because of the crop diversity,
we're moving to very diverse and effective herbicides
most years, except for in sugarbeets,
where we don't have anything to use.
And so we're still listing here cultivation as an option,
which we put out at 70% effective
because it covers about 70% of the ground.
And so this is something that it was funded
by Western Sugar Cooperative to kind of automate
the process of this previous herbicide resistance workshop.
And this was sort of beta tested in 2019.
It was launched in 2020, and currently we have
about 700 unique users on the program,
and we've got that breakdown
between what states are going on there.
And it's currently works for corn, dry beans,
sugarbeets, soybeans, and wheat,
and we're hoping to put a few more uses in here
and a few more things in the future to make it more useful,
but here's the link to it.
I can now take questions if you have 'em,
or you can just go onto the website and play around on there
and ignore the rest of the conversation,
but please use it and give a feedback if you can.
-: All right, thank you, Nevin.
We definitely have times available for questions now.
-: "Is there any natural enemies for the pigweed?"
Not that I'm aware of.
You know, one of the, usually when we talk
about natural enemies, that usually is a question
for sort of traditional bio-control
where you're taking an insect pest of a, let's say,
a weed from its natural habitat and trying to put it
into where the weed's introduced at to control it.
It's used a lot in range situations.
But the fact of the matter is we have,
Palmer amaranth's native to the U.S.,
so if there's a natural enemy
that's gonna be targeting the Palmer,
it likely would've spread, you know,
as the Palmer moved out.
And as far as I'm aware there isn't, and I wouldn't imagine
Palmer amaranth to be a good candidate
for a traditional bio-control
compared to some other situations.
Second question, "Have we found dicamba resistance
in Nebraska for Palmer?"
Other people in the chat can chime in if I'm wrong,
but I don't believe we've found that yet in Nebraska.
We have found dicamba resistance in kochia, though.
The next question by John Thomas,
"Does waterhemp have season-long emergence
like Palmer amaranth?"
Yes, I don't know, I had one year Palmer came up
as early as late April.
That was kind of a fluke, though.
I haven't, usually it's coming up about mid May.
Waterhemp, I just don't see as much
in the panhandle of Nebraska, and so I can't speak
with authority as if it's exactly lined up.
But generally, both those are considered plants
that emerge all season long.
"What is the best pre for you in dry bean,
and what is in sugarbeet, recommendation please."
For Palmer control, I'm assuming what you're asking
is for Palmer control, and in dry edible bean,
the PPI programs work best, but that's a lotta tillage.
If you're not doing that, then your only other option really
is pendimethalin or Prowl plus Outlook
or pendimethalin plus Dual,
or pendimethalin, sorry,
Prowl plus Outlook or Prowl plus Dual.
Both of 'em work just about as well in sugarbeets.
There are no pre options for dry edible for Palmer control
in the panhandle of Nebraska.
We don't, we have ethofumesate and Ro-Neet.
Both of those do not work well.
Milo's asked am I looking for non-chemical weed control
options like the Weed Zapper or other things?
I've actually, so I have been able to get
pretty good funding from Western Sugar Cooperative
to really try about anything because we just don't,
they need a solution at this point.
So we've tried this thing called a mechanical weed puller,
which didn't work too well.
We're currently doing research on wicking Paraquat,
which is actually looking pretty promising.
We've done some cultivation research in the past,
and nothing's really getting 100%.
The Weed Zapper, I get a lotta questions about that.
I've asked some colleagues that have looked into it,
and the problem with the Weed Zapper
is that the effectiveness really comes down
to how much moisture's in the soil
and also the conductivity of the plant.
So I hear it's really great at sunflowers,
that it actually make those explode,
but for the Amaranthus species, kochia,
lambsquarter, those ones I hear the resistance in the plant
is enough that it's not very effective,
but I haven't done it myself.
I can't really say on that, the Weed Zapper.
It's also an expensive piece of equipment to just try out,
but we haven't looked at the Weed Zapper.
"What do you think from your point of view
are the new coming dangerous weeds
in the area where you are working now?"
I don't think that there's any weed
I'm specifically worried about like moving in.
Palmer and waterhemp are still pretty bad.
I guess my concern would be new biotypes of that.
So you know, I don't think ALS-resistant Palmer
started in the panhandle.
Neither did glyphosate-resistant Palmer.
I think both those moved in from other parts of the country.
And you know, we've got parts of the country
that have five-way resistance Palmer amaranth and waterhemp.
Those could move in and be a huge issue in our corn crop
in addition to everything else.
And so right now, we've got good options in corn,
but all it takes is one truckload of contaminated seed
to really reverse that process.
So I guess I'm more concerned about certain biotypes
of the already existing weeds moving in.
Then a question from Adam, "Would integrating cereal rye
leading to dry beans be a management option,
or is it an issue for water usage?"
So actually, yeah, I didn't get into that.
I have a lot of Palmer research I didn't talk about
just because I wanted to focus more
on what my grad students were doing,
but we've got several cover crop projects started.
The biggest issue right now with cover crops
in the panhandle is we're fairly cold,
and so trying to get the cover crop established
after corn isn't really an option
unless you're doing silage corn, and I think we have
two silage machines in the entire panhandle,
so it's fairly rare that it happens.
So when we have done it, though, from a winter crop,
planted cereal, and that hasn't been rye,
it's been winter wheat generally
because the seed's easy to get,
but both pretty equally effective,
we've seen great suppression of Palmer,
and as we're irrigated, usually it's not an issue
with water availability.
The issue we are having though now
is seeing if we can get the same benefits
from cover crops when they're planted in,
let's say, middle of March or early April.
And that's currently where my research is taking me
is to see if we can get those better benefits
from the spring-planted cover crop
because normally the crop preceding our sensitive crops
to weed competition are, is corn,
and we've gotta be able to get that in
sometime between November and May usually.
Oh, we've got one hand-raise here from John Thomas.
Chris: All right, John, go ahead, you should be able
to unmute yourself now. John: Can you hear me?
Nevin: Yes.
John: Okay, you had a question on that rope wicking.
Nevin: Yeah.
John: We had a field of, you know,
it had really tall kochia and Palmer and so forth up north,
and they went in there with Gramoxone and rope-wicked it,
but it seemed like it only killed the top part
of the plant that the wick actually touched,
and the rest of the plant seemed to stay
in pretty good shape.
This was late season.
-: Yeah, so I've done, I've been getting,
I've gotten funding for using a wicker
the last two years to do a research project,
and as I've explained to the granting agency,
that's mostly been me just playing around with it,
because for the rope wicker to work with Paraquat,
you have to have it so wet that it drips
from the upper foliage down the stem,
and it's gotta be that soaked with pesticide
that it's moving all the way down the stem.
The problem is, for it to be that wet,
you're dangerously close to having the Paraquat
just drip off the wicker as you're driving,
through the wick as you're driving through the field,
and then you get splashing where you end up killing
the crop as it hits the crop, too.
And so it's a very, very, very fine line
of not having that, having the right amount of control
and not having too much crop loss.
And I figured out a system for the piece of equipment I use,
and so we've been inviting farmers out
to actually watch us do it, but for,
it really depends on the piece of equipment you're using,
what kind of wick, how you're operating it
to prevent that from occurring.
Yes, so next question, "Do you think you'd have
better efficacy by adding adjuvants to the tank mix?
I did that last year. I tried NIS, I tried crop oil.
I tried some drift reduction agents to make it stickier.
I tried things to make it foamier."
I talked to some people in the industry
about do they have an adjuvant developed
just for wicking, and they don't.
And so we used a whole bunch a stuff,
and nothing really seemed to make that much of a difference.
And so the, it really came down to just the operation
of the machine in our case,
and that was the big overriding factor.
So we've just learned how to use it very well,
that we've actually been able to control Palmer and kochia
and lambsquarter, those are the three species we've had,
in sugarbeets using the wicker.
But it really came down to how you run the machine,
and I wasn't seeing a benefit from any particular adjuvant,
but there might be one I haven't tried,
but we looked at about five different adjuvants.
-: Nevin, did you see Melissa's follow-up question?
"How close has dicamba-resistant Palmer
made it to Nebraska?"
-: No, I see that now.
I really don't know where the nearest-
-: I think there has been some identified
in Kansas that I'm aware of, that's probably the closest.
-: I think that's what I've heard, too, and I,
yeah, I don't know if it's the weed science team
is really good there or really nefarious,
but that's where all the new resistances
in kochia been coming from, too, it seems,
so it seems like we have a lotta things coming up there.
And in the case of kochia,
the dicamba resistance moved it looks like from Kansas
up through Colorado and into Nebraska,
and so that's probably gonna be
a similar route with the pigweeds.
-: All right, well, we've reached 4:30,
so we're gonna officially end the seminar for today.