Weed control with little hammers

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Jodi:

Welcome to the Successful Farming podcast. I'm Jodi Henke. This podcast is brought to you by the Roundup Ready Xtend Crop System, the number one soybean system planted in the U.S. Joining me today is Tommy Butts, an extension weed specialist at the University of Arkansas, and Tommy, herbicides are widely used to control weeds, but as we've discovered, they can't be solely relied upon to do the job. So, first of all, where does a producer start to even develop a plan of action?

Tommy:

I always think the first place to start is to really know what you have out in the field. What kind of weeds are your problem weeds? Which ones are surviving and escaping? What's left? What's giving us the most trouble? And you really want to start to try and develop a plan, then, based around those problematic weeds that year in and year out seem to be giving you trouble, seem to be escaping, seem to be the problem at harvest time, because those are obviously the ones that we're just not taking care of.

Tommy:

So, I think that's always the best place to start, and so being able to either identify those. Or, at the same time, if you know automatically what they are, then trying to figure out why they're not getting controlled in a certain year, so whether that is herbicide resistance, whether it was just a bad environmental year for trying to get herbicides to work, whether we had delays on getting timely applications out, whether we're just not using the best cultural strategies, trying to make an assessment plan from there on maybe why something escaped and what I can do differently to be more successful in a following year.

Jodi:

How do you find out which herbicides, sites of action are working and which ones aren't?

Tommy:

So, here in Arkansas we actually have a pretty robust screening program, so there's a lot of different weeds that we will screen for resistance. Farmers, consultants, everybody can send those in to us and we'll have a pretty big screening program to provide that direct information back to them so they specifically know. Otherwise, if there isn't that kind of program out there, the one thing I'll say is, as a farmer or a consultant, if you're in your fields multiple times and you've seen applications go out and you kind of know that the application setup was pretty good and that your timing was pretty good, and yet you still didn't get complete control, or you've sprayed something multiple times in a season and those weeds still survive, more than likely that site of action is no longer useful or it's not working on that specific weed species that you're targeting.

Tommy:

So, you probably ought to consider that it's resistant and moving on to find a different solution. Any more, here in Arkansas, that's been our big push, is if you see something fail and it fails more than once, just automatically you can assume resistance is there; you should be trying a different mode of action, site of action, because it either is resistant, or if it's not resistance, it's just best practice anyway to be mixing up those sites of action and having more... Well, I always like to say it's having more little hammers working on it than just this one big hammer that we're trying to bring down on it every single time. Really, the same goes for implementing some of these other cultural strategies, is the more little hammers, the more of these different strategies that we can have working on our weed species out there, if one of them fails, we still have a whole bunch of other little hammers working at it. If we're trying to rely on just this one big chemical hammer and that fails, we've got nothing else out there to help us out.

Jodi:

Tommy, you recommend having many little hammers instead of one big one to fight weeds. How do you coach producers to start implementing an integrated weed management program?

Tommy:

The first thing I always like to say is don't do anything you're not comfortable with right off the top. When we start getting into some of these different cultural strategies and integrative weed management things, we need to implement multiple things. But jumping in 100% full bore into 10 different things is never going to be successful, because we just can't successfully manage something that brand new on that large of a scale. So, what I always like to say is if we can implement a couple things this year, a couple things the following year, guess and test what works best on your foam, on certain fields, you can find other of these little hammers that can help benefit you to manage your weed species moving forward.

Tommy:

So, just some examples of that, cover crops get brought up a lot anymore for a lot of different benefits that they can propose. On the weed science side we've shown that there is capability there if we get a good ground cover that we can suppress, especially early season weeds, really, really well. We've even had really good luck at suppressing some of our Palmer amaranth populations, even though it's a later-germinating weed. Because we can get a thick mat it can still hold back a lot of those populations from germinating as well. Now, the challenge comes in is that you have to be able to kill your cover crops so you can plant into it. You have to make sure...

Tommy:

Especially in the south we’re concerned with the green bridge where insects may be could get carried from our winter cover crop over into our following crop. There's water management concerns, whether we're still too wet to plant, or the cover crops have absorbed too much moisture, all those types of things, and so again, that's why I say pick something that you think you can use for a year on a small scale. Try it out, see what works, what doesn't work, what you found of a benefit, what maybe you found as a drawback, and then, moving forward, you can use those little things to build your own battle plan for your fields and your situations, because that's really moving forward any more. Having that broad spectrum plan for everybody that this is what you do and you're going to be clean just isn't going to happen.

Tommy:

It's going to be a farmer-by-farmer basis, a field-by-field basis on here's the plan that will work here, and it works well, but it won't work over here on this farmer or this field, so we need to figure out a different battle plan here. We as a university are generating a lot of information on this and has worked well for us. These things can be implemented if you do these certain things, but again, it still will go back to that farmer-to-farmer basis and a field-by-field basis to make some of things logistically work.

Jodi:

Other than cover crops and herbicides, what other ideas do you throw out for people?

Tommy:

Sure, so here in Arkansas we have a lot of different ideas that we've been throwing out for a couple different problematic weeds here. In Arkansas our main two weeds happen to be Palmer amaranth across our soybean, cotton, corn crops. That is by far number one broadleaf weed that we have. Then our number one grass weed that we have in the state is barnyard grass, and barnyard grass just eats up our rice crop and it just invades a lot of our other corn crops and soybean crops as well. It can do a lot of damage there. So, we're constantly trying to battle those two weeds, mainly.

Tommy:

A couple of the things that we're trying to implement for managing these weeds include deep tillage in the fall. When a lot of these weeds are making seed, they're sitting at the top inch or so of our soil, and that's where they germinate from. If we can do a deep tillage event in the fall, flip that soil over and bury it down at least about six inches deep or so, and then let it sit there... We only do that deep tillage once every four to five years, but we've buried all of those seeds hopefully down deep enough they can't germinate. We hopefully haven't brought any new seeds up to the top. Basically, it's kind of like restarting a soil seed bank, almost. We hopefully don't have as much seed there that the following year we have less to battle from a germination standpoint.

Tommy:

So, that's one thing we've been trying to promote a little bit, is if you get in a real dire situation, if we can deep till it, flip that soil over, hopefully it kind of restarts that soil seed bank. Something else we've been doing a lot of work on is harvest weed seed control. So, again, looking at that seed bank, trying to reduce the amount of seed that goes back there from year to year so we have less problems moving forward. On the harvest weed seed side, we have a couple different options we're looking at. We've looked at our harvest weed seed destructor that literally goes right on to the combine, and any of that small shaft waste material gets dumped into a hammer mill, gets crushed, and it basically renders those weed seeds non-viable.

Tommy:

Some of the research that we've had has shown that it's up to 98, 99% effective on things like Palmer pigweed, barnyard grass, ryegrass, all those types of things. So, it's very effective, but there's still some kinks to be worked out with the size of equipment we have, the hammer mills themselves, the amount of moisture that's kind of going through that that can clog them up and those kinds of things. So, we're still working on that.

Tommy:

But then, another harvest weed seed method that we can use too is narrow windrow burning, so we take our combines and all that shaft coming out the back. We direct it down into a very narrow windrow, and then, after that, all of our shaft, weed seeds, everything had been deposited in this little bitty windrow, we can hopefully burn that windrow, and the temperatures get hot enough to, again, render that seed non-viable, and we don't have that seed constantly returning to the seed bank. So, that's been a big push on our side as well, is just trying to manage that seed bank and use these different options so we're not returning that every year after year.

Jodi:

Those destructors, are they being used in the United States? Is it in Australia, where they're really popular?

Tommy:

In Australia is where they're very common and where most of them are coming out of right now, and they continue to build up popularity in Australia, mainly because in their weed crop over there they've got Italian ryegrass resistance, everything. They have no herbicide options left, so they needed something else, because they literally had zero other options. So, this came out really to start battling that in wheat, and now, in the US, we're trying to test it and change it to be able to be used with our other crops like soybean and rice and wheats, instill things like that here.

Tommy:

That's why we have ran into a few issues down here in the mid-south with soybeans, because a lot of our soybeans still have a lot of moisture in them when we're harvesting them, and that moisture gets into our hammer mill and clogs it up, and they just haven't had to battle that in Australia because they're so dry. So, we're still working out a few details there, and like I said, it's still pretty limited in the U.S., but they're starting to... There's a handful across the states, here and there, that are getting tested and evaluated, both from a university scale and from some private businesses or some private operators. But it's very limited yet.

Jodi:

How long do you think it'll be before it's more commonplace to have this on combines in the United States?

Tommy:

It kind of depends on a couple things. One is working out these kinks that we have, and then the second part of it will be what direction the equipment actually goes. So, as of right now, the way this equipment is is it's an aftermarket part that gets added to the combine after the fact, right? So, a farmer could buy his combine, but then he goes and buys the seed destructor and has to get it put on the combine. So, that right now is a little bit of a log jam. Aftermarket stuff you get into some details, you have to maybe make some modifications to get something on there.

Tommy:

If one of the major manufacturers, whether it's Claas Lexion, John Deere, those kinds of things, and I think they're working on this, but if they start to jump on the fact where they just automatically build these seed destructors into their combine, that could change things in a hurry because it's automatically already all on there. When a farmer goes to buy his combine, the whole system is in place. As far as a timeline, though, I would say we're still, from that standpoint, maybe at least five, 10 years out, somewhere in that intermediate timeframe. With the aftermarket stuff for those growers that are very interested and willing to spend the money and get their hands on it, I mean that, I would say, is more of the short-term, two to five years, let's say, somewhere in there.

Jodi:

If you do your integrated weed management throughout the season, and then you have the seed destructor, you're probably going to be sitting pretty well compared to perhaps a neighbor that doesn't do any of that stuff.

Tommy:

You should be, yes, and the other thing I always like to say too, when you bring this up about the neighbor, this is the other point I always like to make, is integrated weed management is a community effort to battle some of these weed problems. I actually have a picture I took when I was in Wisconsin as a Masters grad student where I'm standing on a road and there's a field to my left and a field to my right, both of soybeans, and on the left you really can't see any weeds whatsoever, and on the field on the right you can see waterhemp basically scattered down the field.

Tommy:

I always ask, "Which field do you think I was there to sample herbicide-resistant waterhemp of?" Most everybody always answers, "Well, the right, because you can see all the pigweeds." I actually did a sample out of that left field, and when I was on that road, what you're seeing is where a custom harvest crew had come in, combined the field on the left, and turned their combine around on the road and shot everything out of the back of their combine into the neighbor's field.

Jodi:

Uh oh.

Tommy:

Just harvesting, it's a normal kind of thought process just doing it. Well, if I would have had an aerial picture, you can see perfect semicircles down that road where the waterhemp was literally shot out of that combine going down there. And so now that neighbor now has herbicide-resistant waterhemp simply because of throwing it out of the back of that combine. So, when it comes to some of these integrated practices, we really all need to look at it as a community approach. We need to work together on it because it's that easy to transfer from one field to another these resistant problems, these really problematic weed species, and so if we all can implement a few of these strategies throughout the year, like you said, if we can make this harvest weed seed control more common across all our farmers, it would help out on that community approach too.

Jodi:

Tommy, you've given our listeners a lot of ideas to help with weed management, so where do they start?

Tommy:

I think the big thing with the battle plan moving forward is if you can identify your weeds, you can start creating your plan from that on what you think you need to implement as far as cultural strategies, chemical strategies, those types of things ahead of time, and make sure to have a contingency plan for that battle plan, because every year we run into things where it throws our first A plan out of whack and we need to go to plan B, C, and D, maybe all the way down to G, H, and I because of weather, rain, other things. So, if we can have at least a few ideas on some of those contingency plans, it'll help us solve a lot in future years moving forward.

Tommy:

I know I've talked a lot about the harvest weed seed destruction, but there's always some of the old cultural standbys you can implement too on trying to narrow our roll width up to canopy faster and eliminate weeds from germinating. Planting earlier in the season can always help so our crop can get a competitive advantage. All those types of things, again, implementing all those little hammers and having those in our battle plan will make it a lot stronger weed control, weed management plan moving forward than if we're just going to strictly rely on we're going to hit it with this herbicide and hope it takes care of all our problems.

Jodi:

Thanks to University of Arkansas extension weed specialist Tommy Butts for being my guest, the Roundup Ready Xtend Crop System, and thank you for listening. For successful farming, I'm Jodi Henke.