|- I'd like to introduce Dr. Aaron Hager.
Dr. Hager is associate professor of Extension Weed Science
at the Department of Crop Sciences, University of Illinois.
He attended Southern Illinois University at Carbondale,
received his BS in plant and soil science,
went on to Michigan State and received his MS there,
and later that month joined the University of Illinois
as a Weed Science Extension Specialist.
He completed his PhD,
joined the Department of Crop Sciences faculty,
and, as an associate professor of Weed Science,
is working on management research
in corn and soybean production systems.
His research is focusing on examining
the biology and management of weed species
that are becoming increasingly common and problematic.
Dr. Hager.
- Well, Jeff, thank you for the introduction.
Also I'd like to thank Dr. Mark Renz for the invitation
and the planning committee for the invitation
to be here today
and to share with you a little bit of the experience
that we've had south of the border.
Now, I come to you today from the state of Illinois
that up until about a year and a half ago
we led the nation.
Now, let me clarify that.
That was not in college football.
(laughter)
Nor was that in the efficiency of state government.
But for a time we actually did lead the nation
in terms of the number of
unique cases of herbicide resistant weeds that we had.
We have about 25.
Now, the good folks in California
in the last couple of years have surpassed us,
and actually Kansas now leads at 27.
That's a tenuous lead for them
because the next time we update our list from Illinois
I'm afraid we're probably going to skyrocket
back up to the top.
But one point I really like to make about
the issues related to resistance,
it's not just an Illinois issue.
It's not just a Wisconsin issue.
This is actually a global issue.
And all this slide represents
is the increase in resistance around the world over time.
And you'll see about in the early part of the 1980s,
that line really began to assume
a fairly significant linear uptick.
And if you fit a regression equation to that portion,
that slope of the line,
what that number tells you is that
every year around the world
we're discovering somewhere between 11 and 12 new cases,
new unique cases of herbicide resistance.
So, again, not anything that's just contained
within the Midwest by any stretch of the imagination.
Now, Devin had a really nice presentation
and alluded to the fact
that really where we see a lot of the problems in Illinois,
and I don't really mean to sound flippant when we say this,
but glyphosate resistance for us
tends to be a bit of old news.
Where we really see the concerns
that in our population of weeds are represented here
is multiple resistance.
If you look at this, this is simple,
multiple resistant or weed species around the world
and have evolved resistance to herbicides
for more than one side of action family.
Now, your first one on this list,
that's a Lolium species from Australia.
And this little creature has evolved resistance now
to herbicides from 11 different classes.
And I forget what we have total,
like 25 or 27 classes of herbicides,
and one species has figured out a way
to get around almost half of those.
Now, your first five species on this list
are all monocot grass species,
and your first broadleaf listed there
is amaranthus tuberculatus.
Of course that is waterhemp.
Now, this is simply a timeline.
A chronology of the introduction
of new site of action herbicides over the years.
Those of you that really want to go back
to some of the first selective ones,
you can go back to the 1940s
and see where the discovery of 2,4-D took place.
If glyphosate is your favorite product,
you'll see somewhere around the 1970s
when it was discovered.
But what I'd like you to focus on for just a moment
is that last dot on the timeline.
That's the HPPD inhibitor chemistry.
I think we had the first one introduced in Illinois
was isoxaflutole balance
somewhere around 1988 or 1989
when that chemistry first came into the market.
But if you drop a line down from that point, folks,
you're talking about a chemistry that's now
or had been discovered, actually,
in the early part of the 1980s.
So even though these are relatively new in the marketplace,
we're talking about a group of chemistry
that's already over 30 years old.
So here's your first quiz for the morning.
If you had to guess,
and it's only a guess, it doesn't matter,
how many site of action families
do you think we'll see commercialized
let's say in the next five years?
We suspect that number is south of one.
(laughter)
How about the next 10 years?
Could very well be the same number.
I've been at Illinois now for 23 years,
I'd like to make 30 but
who knows if that's gonna happen,
we can't even pass a state budget.
(laughter)
Assuming I do last another seven years,
I'd like to see one new herbicide family,
but I really honestly don't know if we will or not.
So that really highlights the fact
that the multiple resistance, I think,
is really going to be of paramount importance for us.
This is simply a pictorial representation, if you would,
of the weed species that we have in Illinois
that have been confirmed resistant to herbicides
from at least one site of action family.
Our oldest example on this list is common lambsquarters.
We've had triazine resistant lambsquarters in Illinois
for probably well over 30 years, perhaps even 40 years.
We've got a couple grass species in Illinois.
Foxtail, for example, that's resistant to ALS materials,
ACCase inhibitors, group one herbicides.
Shattercane, also resistant to water group 2s.
But most of our species are dicots.
Our newest addition on our list for Illinois
is the Palmer amaranth.
We've actually confirmed resistance now
to glyphosate and the ALS inhibitors
in some of our populations of Palmer.
But by far and away that one
that we spend most of our time on,
I would probably estimate
between our weed science research and extension effort,
probably 80% of our time is on waterhemp.
And it's very interesting because,
historically, if you look at some of the old manuscripts,
you'll find out that
waterhemp is actually indigenous to the state of Illinois.
It's always been there. Palmer is not.
Palmer evolved where? It evolved in the Southwest.
It's a desert dwelling plant species that,
quite frankly, grows pretty darn good in Illinois.
But waterhemp has always been there.
But if you would go back in time, say 25 years,
and ask people in Illinois if they knew
what waterhemp was, nobody knew what it was.
There's two people in the entire state
that probably knew what it was.
One was my predecessor and one was my PhD advisor.
Everybody else thought, well,
it looks like pigweed has a red root,
so what does it have to be?
It's probably redroot pigweed, right?
Wrong.
So when Devin spent the time and effort
trying to show you the difference on
how to distinguish some of these things, folks,
pay very, very close attention
because it's very, very important.
Actually, 20 years ago this year,
I did my first plot work with waterhemp
in the state of Illinois, and I had to drive
two-and-a-half hours to the southwest
to work on a population.
Why did we do that?
Because we really did not have much waterhemp
in Champaign County to work with.
Now, we fixed that problem.
(laughter) OK?
I think there's a cornfield in there,
but it's a bit challenging to see that.
Now, if you prefer soybean over corn, guess what,
we solved this issue too.
This is a field up in the Iroquois County
part of Illinois that I think, if I remember correctly,
I don't think this one ever saw a combine.
I think they actually mowed this one down
before all those plants made seed.
So, in essence, here we are.
This is our current status with our waterhemp populations
in most of the part of Illinois.
How do we manage weed species?
Depending on your crop rotation,
depending on the varieties
that you elect or select to grow,
if this plant comes out of the ground,
we may not have a chemical option to control it.
That's where we are.
Now, resistance in waterhemp happens,
and it happens, unfortunately,
with a relatively high frequency.
And there's a couple of
very important biological reasons that help explain this.
And Devin alluded to one, actually both of these, earlier.
Number one is waterhemp called a dioecious species.
So any plant that you see in the field
is either a male or a female.
That's all that big fancy word means.
Now, what do the male plants do?
Yeah, their only chore is to make pollen, right?
And the females, what do they do?
They make the seed, OK.
But if you have separate plants,
what's that mean about its biology?
What has to take place for that female to make seed?
Yeah, waterhemp is an obligate outcrossing species, right?
Pollen has to move from the males to the females.
Now, the other important biological characteristic
is that waterhemp females can produce
a tremendous amount of seed.
It's been published in the literature
well over a million seeds per female plant.
Now, when we write about that amount
in the scientific literature, there's a very important term
that we use to describe the quantity of seed
that female waterhemp plants make.
And if you want to make a note on this,
it's probably a good idea.
We call that a lot.
(laughter)
They make a lot.
You don't really have to remember absolute numbers.
Just remember that these females make a lot of seed,
they're small, and they move very, very readily.
Perhaps one of the best weed seed spreaders
ever invented by man is
these big behemoth machines we put in the fall.
We call them combines.
They're actually really good weed seed spreaders.
They will move these seeds around quite a bit.
Now, just for sake of argument here,
let's assume we've got a female
who can make a million seeds, OK?
How many flowers does she have to have
to make a million seeds?
- A lot.
(laughter) - I liked that.
I've never had that before, thank you very much.
I'm not very good in mathematics,
so I can't really trick you with mathematical questions,
but I'll give you a clue here.
It's a one-to-one relationship.
So if she makes a million seeds, how many flowers does she have?
She has a million.
At least theoretically.
At least theoretically,
how many different male plants could donate pollen
to that female?
A million.
So if you had to think about that long enough,
what do you think is the
genetic diversity of a species like waterhemp?
Is it fairly narrow, or do you think it's fairly broad?
It's honking wide, OK?
So it makes a lot of seed.
Now, part of this genetic diversity in waterhemp
is expressed how?
Well, in the evolution of resistance.
So right now in Illinois
we've actually documented at least five,
and it's soon to be six,
instances of resistant to five to six herbicide classes.
Now, our sixth one
will be to the group four herbicides,
to the 2,4-D for example.
And you can see the ones that we've had listed on here.
As a matter of fact, the HPPD inhibitors,
that was first discovered, we found that field about 2009.
Long-term seed corn production field
right smack dab in the middle of the state of Illinois.
HPPD inhibitors, what did we say, which class was that one?
The last commercial class developed, right?
And we've already documented.
This was the first reported resistance
of that class of herbicide
anywhere in the world, and guess what it was?
It was in waterhemp.
So, some total here we are.
Here we've got a species in our state
that 25 years ago hardly anybody even recognized
that now has evolved resistance to herbicides
from six different classes.
Now, if you had this, if you had a field over here
that had glyphosate resistant waterhemp,
right off the bat what does that do to you
in terms of your management plans?
Number one, you've got to remember that it's there, right?
That glyphosate would not necessarily be the
most effective option to try to control it.
If you've got resistance now to six different classes
and you've got a separate field, folks,
there's no law in biology
that says this has to be the same in this other field.
This one may be resistant to triazine.
Your third field may be ALS.
The fourth may be HPPD, right?
So if you had to really have resistance,
that ain't a bad way to have it.
It just comes down, now you've got to keep track of
which fields have what type of resistance
and what would work and what wouldn't work.
But, unfortunately, that's not where our problem lies.
Our problem lies right here.
And that's multiple resistance in waterhemp.
Now, when we talk about multiple resistance,
we always have to define our scale.
So you could think of multiple resistance like the example
on the left-hand side of the screen over here.
It says multiple resistance at the population level.
Think of this as any field that you farm.
So, on any field that you farm,
doesn't matter if it's five acres or 500 acres,
size doesn't matter,
you'd have plants like the one
that's white with no letters by it
that's basically sensitive to any herbicide
that you would spray to it.
You would have other plants
that are resistant to herbicide A,
whatever A is, it doesn't matter.
Still others resistant to B.
Still others resistant to herbicide C.
Now, if you had to come up with a
quick and easy and simple solution
to fix this problem, so to speak,
what's the easiest thing that you could do
to solve that problem at the population level?
Why don't you put A, B, and C together?
Wouldn't that work?
Sure it would, right?
Because A, B, or C will kill the sensitive ones.
B and C would kill A.
C and B would kill, I'm sorry,
A and B would kill C, et cetera, et cetera, et cetera.
Pretty simple, right? Not where we're going.
Unfortunately, where our problem lies
is on the right side of the screen.
And what do you do now
when you put A, B, and C together in the same plant?
How do you fix that?
Go ahead and say it.
Somebody always says D, right?
Know the problem with that answer?
We ain't got D.
And I don't think we're gonna have D
any time in the foreseeable future, that's the challenge.
And, actually, truthfully,
this slide is a little bit outdated because
that really should say A, B, C, D, and E.
Just to give you an idea what this looks like,
if you want to see this population we call WCS,
that's our sensitive that we use in our greenhouse trials,
we can still kill it with Atrazine.
We can kill it with Cobra.
Heck, we can even kill it with Raptor.
But the one on the right is a resistant population,
actually the first three-way resistant population
that we found in Illinois.
It doesn't matter if you put Atrazine down,
follow up with Cobra and Raptor tank mix,
or, heck, you can put all three of them together
in a tank and go spray it, guess what?
It doesn't die.
Now, for us now we've actually had resistance evolve
to these classes of herbicides in our state.
Group 2s, 14s, 27s, 5s, and 4s.
We always have to remind people
we have to be very, very aware,
is this occurring at a population level
or the individual plant level?
And, unfortunately, more and more
we're seeing this at the individual plant level.
When we first found that three-way resistant population
over in Adams County, it was about 2001 and 2002.
Boy, we were just elated.
Three-way resistance in a single plant.
We don't really get that excited anymore.
Those are fairly common for us.
A couple years ago,
one of Dr. Tranel's students published a paper
that had four-way resistance in individual plants.
We're working on the manuscripts now, for five.
How many think it'll go to six?
Yeah, how about seven?
Yeah, however high you wanna go,
it's probably going to go there, OK?
So, if you look at our expansion over time,
Devin alluded to this in his presentation,
these are based on those molecular assays that we have.
And these data basically are generated
from people who would send tissue samples in for us
to run that assay.
We started a pilot on this about 2009.
We actually had some very good funding
from the Illinois Soybean Association.
So we opened this up basically statewide in 2010.
And you can just simply see
the progression of this over time.
Now, if you look at 2012,
there's not a lot in the very southern part of Illinois,
and that doesn't necessarily mean
that glyphosate resistant waterhemp
is not in the southern part of Illinois.
You know what that really means?
In 2012, folks in the southern part
of the state figured out that they had it.
They didn't need us to tell them that they had it,
they knew it.
Our greatest resistance is
not necessarily in weeds in Illinois.
It's just simply in farmer beliefs
that this is really happening.
The farther north you would go into Illinois,
the more denial that, well, we don't have it,
it's only a problem in southern Illinois.
So, about five years ago
we changed the definition of southern Illinois.
When we talk about resistance, we now define southern Illinois
as all farmed ground in Illinois, south of Wisconsin.
(laughter)
That's where the challenge of it is.
We've got 102 counties in Illinois.
We basically feel as though
we probably could identify glyphosate resistance
in all those counties.
Here's our significant problem.
Here's the example of multiple resistant
now, granted, this is at the field level.
These are based on 2014 samples.
If you look at these, we had about
72% of the samples had glyphosate resistance,
or, I'm sorry, the fields,
and 67% had resistance to the PPO inhibitors.
How many had both?
What number do we look at there?
Over half, 52% of the fields had both.
What is the significance of these data?
If you think about a soybean producing system,
let me ask you this:
if you elect to grow a Roundup Ready variety
or if you elect to grow conventional variety,
can someone name all the classes of herbicide
that you could apply post-emergence
to control emerged waterhemp?
They're on the screen.
The only one we don't list are the ALS inhibitors,
and Devin alluded to this in his presentation.
Functionally, we have lost that entire class
of herbicides in Illinois.
It used to be very, very effective against waterhemp
and many of our other pigweed species,
but we don't even screen
for that type of resistance anymore.
It's easier to assume it's there.
So if I've got a system of Roundup Ready
or conventional soybean varieties,
I could either spray Roundup on the Roundup varieties
or I could spray the foliar-applied PPO inhibitors
on the conventional and that's it.
Are we gonna manage this?
That's our most significant challenge.
So here we are.
Basically, we've got this evolved resistance now.
These are the various mechanisms
that we've identified
that confer these various types of resistance.
Actually, for ALS inhibitors we have two.
We have a target site, which is very, very common,
but about three years ago we stumbled upon the fact
that we actually have a
non-target site based ALS resistance mechanism also.
For the photosynthetic inhibitors, the same thing.
A target side and a non-target, but, here,
by far and away the most common one that we had
is the non-target site.
For the PPO inhibitors, it's a very unique target site.
It's actually what's called a codon deletion,
that allows these plants to survive the PPO inhibitors.
For the glyphosate or the EPSPS,
we actually have two, a target site and a non-target site.
The one that's really got us a bit unnerved
is the last one
because a mechanism of resistance in the HPPD inhibitors
is actually a metabolic resistance.
Folks, if that becomes more common
as we are very concerned it will,
that's gonna be a game changer.
The reason I said that,
if you think back to that first slide
where I showed you
multiple resistant species around the world,
anybody remember what that top one was?
How many different classes was it resistant to?
11, you know how it is?
A lot of that's through enhanced metabolism.
If that becomes more common,
we're gonna have sit down and rewrite the textbooks.
And we really think that our greatest challenge,
at least for us in waterhemp, and if it's not gonna waterhemp,
it'll be Palmer, because we got that one
warming up in the bullpen, so to speak,
it's going to be with the populations
that have the multiple resistance in these.
So I think we're OK for time. Jeff, you let me know for sure.
Anybody have any questions here that we can try to answer?
(applause)