Hello. My name is Tommy Butts, extension weed scientist
with the University of Arkansas System Division of Agriculture.
And thank you for joining me today
for the rice and soybean virtual field day tour.
Today, I'm actually standing in one of my trials located
here at the Rohwer Research Station in southeast Arkansas.
And I wanted to cover a few different topics revolving around residual herbicide
chemistries and specifically residuals being used in our rice herbicide programs.
One of the first topics that I wanted to hit on right away
is the mentality that Dr. Tom Barber mentions all the time.
That two is better than one.
And I really wanted to highlight that here
with a few different plots of how two multiple effective modes of action,
especially in our residuals and our pre-emergence residuals,
can get us better control.
So the first plot I'd like you to look at
is right over there at the edge of the screen.
That plot is Command alone.
And again, in this trial, this was just strictly looking at pre-
emergence residual herbicides and the length of their residuals.
And so we have not applied anything else post.
It's just strictly the pre's that I'm talking about today.
And those pre's did go out about six or seven weeks ago.
So it has been quite a bit of time since we applied those chemistries.
Now, that plot over there, again, received Command alone
here on this heavy clay soil at Rohwer, we used a quart per acre rate.
And you'll notice we did get, you know, halfway decent grass control,
especially compared to our non-treated control plot.
We got, you know, really good grass control there.
But when we're relying on that one chemistry solely by itself, you can see
we still did have a lot of grass escapes.
Also, Command is not good for broadleaf weed control.
So you'll see a lot of hemp sesbania or coffeebean that has broken through.
So we didn't get that diverse weed spectrum.
And then also that plays into by only using
one mode of action out there in that tank mix, that really plays into quickening
or hastening the evolution of herbicide resistance.
So we really want to try and avoid doing that as much as possible,
because Command is a staple herbicide in our rice crop.
It does a lot of work for us, and we want to save that as long as we
possibly can from developing resistance in our barnyardgrass populations.
Now, like I just mentioned and like Dr. Tom
Barber mentions, two is always better than one.
If we look at this plot right next to me,
this is actually Command plus Facet Pre.
And again, those two
effective modes of action working together greatly enhanced our weed control.
Also, the benefits of adding Facet into that mix is we can increase the diversity
of spectrum of weeds that we get.
You'll notice that that helped us control a lot of our coffeebean or hemp sesbania
in this plot as well.
It will also give us a little flatsedge
control and a few other weed species as well.
In this plot, we used a
quart rate of Command again and the forty three ounce per acre rate of Facet.
This really is probably
one of my top primary recommendations for our first residuals to go out in rice.
Consistently in our research,
we see that Facet works better as a residual,
especially when pairing it with Command.
And so I'd much rather use it up front, get as much activity out of it
as possible, rather than saving it for the post-emergence side, where
we've often seen some mixed results as far as controlling our barnyardgrass.
So, again, Command plus Facet, from a residual standpoint,
consistently ends up being one of our top residual programs.
And you can see the level of control that we have, even six
or seven weeks later here out of that mix.
Now, if we go down the line,
another two-way mix that worked really well for us
here at Rohwer was Command plus Prowl applied delayed pre.
Now the Prowl, we used a 2.1
pint per acre rate and again, the Command was a quart per acre rate.
Now with that mix, we have to apply
it delayed pre, once that seed imbibes water.
But again, you'll notice very good grass
control from two effective modes of action in there at one time.
You'll also notice that the Prowl brings
a little bit of broadleaf activity to the table as well.
It's it's not excellent by any means,
but it did help us a little bit on some of those broadleaves.
It gives us a little bit of extra control there.
So, again, we can cover a little bit more diverse weed spectrum.
So, again, Command and Prowl worked very well for us from a delayed pre aspect.
Now, the final two
plots, I wanted to show are Command plus Gambit and Command plus Sharpen.
Now, the Gambit rate we used here was two ounces
per acre, and the Sharpen rate we used was three ounces per acre.
And what you'll notice here is the grass
control is equal between these two, because pretty much
all the work is coming from the Command on the grass control front.
So we're really looking at some of the other diverse weeds or broadleaf activity.
Gambit does a very good job on the coffeebean that you can see here
and also is very good for yellow nutsedge control and several other odds and ends
broadleaves. Sharpen is also good on a broad spectrum of different broadleaves.
It will give us some rice flatsedge control,
but really minimal yellow nutsedge control.
So, you know, with a Sharpen, we can get rice flatsedge
with the Gambit, we can get yellow nutsedge,
we can get broadleaves with both, et cetera.
Now, what do I typically recommend between those two as far as
my residual program?
Well I tend to lean towards Sharpen,
which may look a little shocking to you
when you look at these two plots, because really I honestly say
the Gambit plot looks like it gives me a little bit better broadleaf
weed control, as you can see.
But the difference here, the reason why I don't like to use my Gambit in my pre-
emergence program, I like to save it for a post-
emergence shot, is because if I use two ounces of Gambit pre,
I've used my season limit for the halosulfuron,
so I can no longer apply Permit, Permit Plus or Gambit later on in the season.
And as you can see in both of these plots, we do have a few coffeebean escapes.
If we have a bad yellow nutsedge problem, we'll have some escapes there.
So I like to use my Sharpen at three ounces pre to try and knock out
a bunch of those broad leaves and other things
and save that Gambit for post for cleaning up
any escapes that I might have and again,
cover that diverse weed spectrum if I have multiple other broadleaves
or yellow nutsedge also emerge.
So, again, you know,
I think Gambit is
slightly better than Sharpen as far as that residual component,
especially for the weeds that they're targeting.
But using three ounces of Sharpen as opposed
to only having one ounce of Sharpen that we can apply post.
I like to use that as my residual up front and save that Gambit
for my post-emergence applications to really clean everything up
and then give me a little bit of residual activity late.
So that's really the driver behind that recommendation.
In this second section of the weed control portion of the rice virtual field day,
I wanted to hit a little bit on row rice or furrow-irrgated rice weed control.
So today I'm actually standing in one of our row
rice trials, located at the University
of Arkansas Pine Bluff Small Farm Outreach Center located just north of Lonoke.
In this trial here, what we were really looking at
were program approaches for season long, weed control management in a
row rice situation.
A few takeaways that we have in this trial this year is the critical nature
of overlapping residuals and the timing of those.
We need those timings at 14 days
after our initial residual application, which I'll show you some plots
in a second here on that.
And then also of critical, you know,
the importance of selecting appropriate herbicides post to manage
what weed species that we have in our row rice fields.
So, for example, here in this field or this trial,
we have a real heavy population of barnyardgrass.
We also have a pretty bad crabgrass population
and then a little bit of coffeebean sprinkled in and then as well,
some sedges so are pretty good rice flatsedge population
as well as a few yellow nutsedge are sprinkled in here and there.
And so you really need to select post emergence products
that are effective on that diverse weed spectrum,
as well as the overlapping residuals we talked about.
And the final thing is, it really, we need to expect
that this is going to take us a minimum of three
herbicide applications in the season, but more than likely, it may take four
and in each one of those tank mix or in each one of those applications,
we're going to have have to have
multiple herbicides tank mixed together to really get a clean season-long control
such as can be seen in this plot right next to me here.
Now, for this plot specifically,
this is one of our cleanest plots we have out here.
And this followed a lot of those rules that I just talked about.
So our initial application in this was a pre-emergence
application of Command plus Sharpen.
That gives us grass control as well as some broadleaf residual control
and a little bit of flatsedge residual control with the Sharpen.
Now, Facet may also be a good option or at least quinclorac
to mix into that pre as well.
I really like moving that quinclorac
product up as a residual, especially right on the front end,
and that Facet or quinclorac
part can give us a lot of good activity on flatsedge grasses as well.
So it's just kind of a good broad spectrum herbicide to maybe throw in as well.
What we did for our second application in this was
we followed it up at about 14 days later, and that's really critical.
That 14 day timing is critical.
And at that point, we added in a post-emergence product
to kill any grass that was up, but also added residual to overlap.
And so that second application,
we actually added a shot of Preface plus Command again.
So we can overlap our Command residual,
W\we got a little bit more residual from Preface,
but we also got some post activity from that as well. Oh, excuse me, too.
I also forgot in that second application we had Gambit in as well.
And so we we had post-emergence activity of Gambit on our sedges.
We also get a little bit of residual from that on sedges.
And it takes out our coffeebean and broadleaves.
So again, that second shot we have Preface, Gambit
and another overlapping shot of Command.
That made it — got us to our third application,
which was basically then another fourteen, twenty one days later
after that, geting to that four to five leaf close to pre-flood timing.
And at that application in this plot here, we added a second shot of Preface
and followed it up with another shot of a broadleaf material.
In this case, it was Aim.
But you really could implement numerous.
different options there,
such as if you haven't used Gambit earlier, you can use Gambit now.
You could also use something like Ultra Blazer for a broadleaf material,
or you could go towards Loyant.
And Loyant is really good for a lot of different broadleaf materials as well.
Now, in this trial here, I don't have a lot of Palmer
amaranth population,
but if you have a bad Palmer population,
which we normally do in our row rice acres, you're definitely going
to want to be able to use Loyant at some point
in your application process, your three applications there.
And you may want to think about Grandstand and propanil as well.
My typical recommendation is that I like to see Grandstand
and propanil up in like that second herbicide application
when our pigweeds may still be small.
The burning action of propanil is very, very good to kill small pigweeds.
And if nothing else, it'll burn some bigger ones back
and give you more time for that Loyant application.
And then when you come back in
for your Loyant application about that third timing,
you know, if they're if they're about six to eight inches or less,
we can drop our rate of Loyant down to eight ounces
and still be very successful at managing that Palmer amaranth population.
So just be aware of that. Out here
we did not have that weed species, but that is a good combination
to add into programs if you have a bad Palmer amaranth population.
Now, when we look at other plots where we struggle to get weed control,
it always broke down to those things that I already mentioned.
So in a couple of these bad plots
that I'll show, the first situation was we skipped that timing
and we ended up waiting 21 to 28 days for our first overlapping residual chemistry.
If we did that, if we waited that long, we had escapes
and we just weren't able to get them under control
or get enough of the next flush kill.
And so we ended up with losses in weed controlled because of that timing.
So, again, 14 days after the pre is really critical
to hit it with our overlapping residuals and potentially a post product.
The second plot that we're going to look at here where we lost control was
we did have overlapping residuals at that 14 day after.
However, we had nothing from a post
perspective to actually manage weeds that had already come out of the ground.
And so in those aspects, and especially in this trial,
we already had some breakthroughs and we did not get those under control.
And even though we overlapped residuals,
we just didn't get anything that was up until we have an escape of sedges
and escape of a few barnyardgrass plants.
And so it's really critical to make sure we're closely
scouting our row rice acres so we know, you know, if we need to add
in that post-emergence product with our overlapping residual
and which ones are best suited for us, whether we're going
after sedges or broadleaves or grasses, and we can more appropriately select
that post-emergence product.
So, again, out here in this row
rice trial, our main takeaway is we need overlap residuals
at 14 days to be most successful with with that residual program .
We have to be scouting carefully and making sure that we're applying
post-emergence products in a timely fashion as well,
and the appropriate post herbicides for what weeds have in that plot.
And then finally, we need to make sure
that we're probably expecting three to four herbicide
applications to really maintain weed free throughout the season.
Now, one of the other final things that I should mention today in this row
rice trial is, you know, I mentioned a few specific herbicide
products and programs that were really successful out here,
but that by no means should mean that
we put those specific programs on 100 percent of our acres.
You know, really what I wanted to highlight was the criticalness of those
that interval timing, those 14 day intervals
between overlapping residuals, and then how critical it is
for us to select appropriate post-emergence herbicides
for what weed spectrum that we have out there
and make sure that those are going out in a timely fashion as well .
And so those are the main things I wanted to take away.
But we could select multiple different herbicides that are great options.
You know, on the pre-emergence standpoint, I talked a lot about Command and Sharpen.
But, you know, things like Facet, in that pre-emergence program are great.
Bolero can be a good delayed pre option, you know, up front.
So can Prowl, you know, there's a lot of different things
that we can work in our Preface or Newpath on that residual front up front.
There's a lot of different options there from a residual standpoint.
When we start talking about the post-
emergence products, you know, things like Ricestar, Clincher,
Regimen are all great for grass control options.
Loyant, Ultra Blazer,
you know, the Gambits, Permit, Permit Plus's of the world are great
for broadleaf control and some for yellow nutsedge control.
There, you know, maybe Basagran and Propanil for rice flatsedge.
There's all kinds of different options and combinations there that we can do
to manage what we have in that field.
But the most critical thing that it boils back to again
is that we overlap residuals at a 14 day interval.
We're scouting appropriately and detecting which weeds we have out there
and which ones are emerged,
and then appropriately selecting those post-
emergence products to battle those specific weeds.
So, again, I just wanted to highlight that as well.
So for the last part of the weed control section of this rice virtual field day,
I wanted to just kind of quickly hit
on some federally funded projects that we have going on across the state.
So today I'm actually at the University of Arkansas Pine Bluff Small
Farm Outreach Center here located just north of Lonoke.
We have three of these trials that are all federally funded
through the USDA National Institute of Food and Agriculture, or NIFA.
These projects are really trying
to investigate some different cultural strategies
that we can maybe implement in our rice acres to help our weed control programs
so specifically in this study that we're standing in,
we're looking at the drill spacing effect on weed control
and how drill spacing in combination with maybe what nozzle type we select
may influence our weed control.
So right here to my right, your left,
this is a plot drilled at a seven and a half inch spacing,
which is pretty much our standard across the state right now.
And on my left, your right, over here
is actually a plot drilled at a 15 inch spacing.
Now, 15 inch seems, you know, pretty unheard of at this moment.
I know there's a couple farmers out there trying it at this point,
but I can really foresee this, you know, starting to increase
in the near future with all the precision agricultural
capabilities, vacuum planters, all those kinds of things.
If we get a seed plate for it.
You never know, you know, what might be capable.
So we kind of wanted to investigate these different drill spacing
and how that might impact our weed control.
So we have anywhere from five-inch
spacing up to this 15-inch spacing is our maximum.
Now, like I mentioned in this trial specifically, we're
also looking at nozzle type and how that might affect our weed control.
So anywhere from a,
you know, a very fine droplet size, up
to a really ultra coarse, very large droplet size we're testing.
And then we're also testing a couple of single fan nozzles
versus dual fan nozzles
to see if we can increase our coverage and increase our weed control.
Now, in a couple of the other studies that we have, we're also investigating
the same drill spacings, but then variety impact.
So whether you know, a medium grain versus a long grain conventional or,
you know, a long grain conventional inbred, I should say, a long
grain conventional hybrid or a full page hybrid.
You know how that might impact this drill spacing effect.
And then the final study
as a part of this is actually looking in furrow irrigated rice or row rice.
And again, looking at the impact of drill spacing plus bed width.
So whether our bed width is 30, 38 or 60 inches,
how might that change our weed community or weed ecosystem,
and then our overall weed control in our rice acres?
So, again, I don't have any data to really share on this.
This is the first year for this.
But I just wanted to highlight
that we have these studies at a couple locations in the state,
as well as a collaboration with Mississippi State University,
who's are repeating these projects for us over there in Stoneville as well.
So I just wanted to highlight
that and be on the lookout for this in the near future.
I do have a graduate student
who will be working with this project as his master's degree.
So Mr. Noah Reed will be working on this, and just be on the lookout
in the future for some results coming out of these studies.
Thank you very much for joining us today for the weed science portion
of the University of Arkansas System Division of Agriculture,
Rice Virtual Field Day.
All we really want to say thank you for your continued support
and viewing of these online virtual extension events.
I also wanted to thank the Arkansas Rice
Research and Promotion Board for their continued support
and funding of a lot of our research and extension events.
Without that funding and support,
we would not be able to conduct the trials and extension events that we do.
So that is greatly appreciated.
I also would like to thank the USDA NIFA program
for their funding and support of some of our projects,
as well as our industry sponsors and gifts that they provide to us
and allow us to conduct as much as we do.
I do want to thank the University of Arkansas
System Division of Agriculture for their support
and continued efforts to make extension events like this happen.
And finally, I owe a big thank you to my weed science
crew for their continued hard work at,
you know, establishing these trials, maintaining them throughout the year,
you know, getting all our treatments out and harvesting at the end of the year
without all of their hard work.
You know, I would not be able to talk about as much as I can
and have the insights from research supported conclusions that we do, so big
thank you to them for their continued hard work with all of our research trials
across the state.
Finally, once again, just thank you for continuing
to support the University of Arkansas System
Division of Agriculture, and especially our Cooperative Extension
Service with our events that we're working on here,
even virtually. And if you ever have any questions at all,
please don't hesitate to reach out. Thank you.