November 13, 2024 • 43 mins
This week on the War Against Weeds Podcast, we have Drs. Dale Shaner and Tom Mueller joining us to discuss enhanced degradation of triazine herbicides!
You can find more information on this topic at these links below provided by our guests.
https://utia.tennessee.edu/publications/wp-content/uploads/sites/269/2023/10/PB1580.pdf
https://scijournals.onlinelibrary.wiley.com/doi/abs/10.1002/ps.1909
Thanks for listening!
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Unknown (00:00):
Music.
Alyssa Essman (00:07):
Welcome back to the war against weeds podcast.
This is Alyssa Essman, WeedScience extension specialist at
The Ohio State. Today I'm joinedby my co host Sarah Lancaster,
Weed Science extensionspecialist at Kansas State. Hey,
Sarah,
Sarah Lancaster (00:19):
howdy, Alyssa.
Alyssa Essman (00:21):
Today, we're joined by two professionals to
talk all about our topic,enhanced degradation of triazine
herbicides. And I think we'vegot two folks who can really
give us some really greatinsight into this topic. So
we've got doctors, Dale Shanerand Tom Mueller. So we want to
give you a second to introduceyourselves and a little bit
about where you're coming fromand what you do? So, Dale, do
(00:42):
you want to start us off andtell us a little bit about
yourself?
Dale Shaner (00:46):
Well, I am a weed scientist. I worked in the area
for about 40 years. I am nowretired, living in the mountains
in Colorado. In my career, Iworked on the imidazolone and
herbicides, and I also did a lotof work on herbicide soil
interactions while I worked forUSDA for about 11 years before I
(01:08):
retired.
Alyssa Essman (01:10):
Awesome. Well, sounds like you're very well
equipped to help us out withthis information. Tom, where are
you coming from?
Tom Mueller (01:17):
Well, I'm just happy to be here. Just a little
background on myself. I have aBS from Illinois. I work for in
the real world for two years. Ihave a master's from Kentucky, a
PhD from Georgia, a post doc inMississippi for a couple years.
And then I've been at theUniversity of Tennessee for 33
years, and work in the area ofenvironmental fate of herbicides
in soils and in air and water.And I just want to say that the
(01:41):
views expressed by Tom Muellerdo not represent the views of
the University of Tennessee orany other associated group. And
also, this is being taped rightbefore an election. I just want
to say that although I haven'tgiven it yet, I still approve
this message.
Alyssa Essman (01:56):
Fabulous. Okay, so I thought we'd start off with
a little bit of context, becauseI think this is a really
interesting area of work, andI'm curious to know how each of
you, you know, got into this. SoDale, maybe we can start with
you. You know, what interestedyou in this topic?
Dale Shaner (02:16):
Well, I kind of stumbled into it when I joined
USDA, the unit that I wasinvolved with was in precision
agriculture, and I was doing astudy on looking at the effect
of different parts of a field onherbicide behavior in the soil.
(02:36):
And in this particular field, itwas a farmer's field he had
applied Atrazine, and I hadcollected soils from different
parts of the field withdifferent soil characteristics,
and I had collected samples forabout six weeks, and so I was
going to start doing theanalysis. And I first started
(02:58):
looking at Atrazine, and when Itried to measure the levels of
Atrazine, there wasn't anythingthere. And that really puzzled
me. So I thought, Well, maybe hedidn't apply what he thought he
applied. So then I went backthrough the samples, and I
started with the first samplethat I collected right after
application. And indeed, therewas Atrazine there, but then I
(03:20):
had collected over several, youknow, every week for six weeks,
and I started looking goingforward, and after two weeks,
there was no more accuracy. AndI thought, well, maybe my
analysis is wrong or somethingelse. And so then I took the
soils into the lab and did a labstudy and found indeed, that the
(03:41):
half life of Atrazine in the labwas about three days, and the
literature said it should beabout 60 days. And so that's
what started me in the wholething, just trying to understand
what happened, saw this enhanceddegradation, and then looking at
the literature, found out thiswasn't a new phenomenon, and I
worked with a weed scientistfrom USDA in Mississippi, Dr
(04:06):
Krutz, and he had been workingon it for a while, and then we
just went from there.
Alyssa Essman (04:13):
So interesting. I love when it seems like a real
world problem, where you saidyou were working with a farmer's
field and you just happen tonotice this. That's that's kind
of fun. So Tom, how did you getinto this work?
Tom Mueller (04:24):
Well, research on herbicide fading sorrows was
prevalent in many universitiesin the 1980s and 90s, with many
prominent research groupsworking in this area. And I'm
going to consider this sort of ahistorical document. So I made a
list of the folks who used towork in this area. So I'm just
going to read these off. Get PatShea at Nebraska Bill Costco in
Minnesota. Jerry Weber at NorthCarolina State. Terry laby at
(04:45):
Arkansas, although John maticewas a brilliant chemist and
scientist, so really Matisse wasor Matisse was actually the
smart guy there. Morris Merkelat Texas A and M. David Shaw,
Mississippi State. Bill banks atGeorgia. Bill Witt at Kentucky.
Jason Cruz, which Dale isalready. Mentioned, and Dale
Shaner At Colorado. Nowcurrently, there are very few
groups working on herbicide fatein soils. I mean, Tim gray at
(05:06):
Georgia, Travis Gannon in turfin North Carolina State, and me
in Tennessee. And the reason forthis is there's, you know, we
could talk about another time,but I just have always been
looking at it from an agronomicperspective. And so that's what
we'll talk about, it. Why, whenwe get into why we looked at
enhanced degradation was It wassimilar to what Dale was talking
(05:28):
about, except that we werelooking at just in general,
atrazine wasn't working like itwas before. So that's how we got
into the specific topic.
Alyssa Essman (05:37):
Yeah so that's kind of a great segue, talking
about, you know, atrazine wasn'tworking like it was before. Can
you guys kind of walk us throughwhat we mean by enhanced
degradation and kind of lay outthis process for us.
Tom Mueller (05:51):
You wanna go first Dale? You want me to go?
Dale Shaner (05:54):
You can go.
Tom Mueller (05:56):
Okay, well, atrazine was, at one time, the
foundational herbicide use andweed control in corn, grain
sorghum and sugar cane. And itwas also used in many other
situations, but predominantly,most pounds went on field corn.
It was normally appliedimmediately before planting,
immediately after planting.Although it can be used early
post and Dale knows more than Ido. It's a photo system to
inhibitor and all that good modeof action stuff. So it was
(06:20):
basically used on everything.And Atrazine is a triazine
chemical. And I'm not even goingto try to do anything chemically
related to what explaining whata triazine is. All I'm going to
say is that there are nonaturally occurring triazines
from an environmentalperspective. I'm at least, I'm
pretty sure that's true. And if,if that's not true, Dr Shaner
(06:40):
can correct me on that. Sobefore we go any further, let's
discuss exactly what enhancedmicrobial degradation of
chemicals means. If I've got anew chemical and it's introduced
into the soil environment, themicrobes will eventually
determine how to best metabolizeor degrade that new molecule. So
enhanced degradation is by nomeans unique to Atrazine, and
(07:01):
many pesticides have had issueswith rapid degradation after
several years of use soilapplied insecticides such as
carbofuran, the carbamathyoateherbicides, which I don't think
anybody uses anymore, they wouldhave special adjuvants added to
them to discourage the enhancedmicrobial degradation. So that's
that's what's happening. And soif you've got a completely novel
(07:23):
type of chemistry now present inthe soil environment, like a
triazine, it has the chance tobe more persistent to microbial
degradation. So like Dr Shanewas saying when it first came
out, atrazine would last a longtime, 60 days, 70 days, easy.
But now with the enhanceddegradation, it just doesn't
last as long. Does that kind ofintroduce the topic of what
(07:44):
we're talking about?
Alyssa Essman (07:46):
Yeah. Yeah, it does. Thank you, Dale, do you
have any thoughts? And also,could you kind of also classify
these what we call adaptedversus non adapted soils?
Dale Shaner (07:55):
Yeah, we do. I did a lot of work with Jason crutz
on this, and non adapted soilsor soils that have never seen
Atrazine, or have had very, veryfew applications of Atrazine.
And when you look at the halflife of Atrazine in those soils,
you will find that it is verylong, comparable to what was the
(08:20):
norm Prior to the discoverytrizin, adapted soils around 60
days, or maybe a little less,with adapted soils, everything
that I've ever looked at, and Ithink Tom would agree, is our
soils that have had multipleapplications of Atrazine. And as
he said, you know, atrazine wasintroduced in the 50s, and so
(08:43):
it's been used now for about 70years. And it's not too
surprising that soils will willour bacteria in the soil will
evolve to start using this newsource of energy. And in the
case of the triazines, one ofthe main reasons they're using
(09:04):
it is for a nitrogen source,because if you have high
nitrogen, it will inhibit thedegradation of Atrazine. So
adapted and non adaptive justreally means, what's the history
of the soil? Has it seen theseherbicides before? If it has,
then you will likely find thesemicroorganisms that will degrade
(09:25):
it.
Alyssa Essman (09:28):
Yeah. So one other question that comes up
then, when we've had, you know,in Ohio this year, we had a wet
spring and a really droughtysummer, and it seems like we're
getting more and more of theseinteresting weather patterns.
And so I'm curious, you know,how do those environmental
conditions, maybe wet soils anddry soils, but also our field
characteristics, things likesoil pH, kind of influence this
(09:51):
process? Dale, do you want tostart us off on this one?
Dale Shaner (09:54):
Yeah, this is an interesting aspect of these
adapted soils. If you look atthe label. For triazines, prior
to the discovery of thesemicroorganisms that degrade it,
you will see that that they saythat Atrazine persists longer in
high pH soils than in acidicsoils, and so that if you have
(10:17):
high pH soils, you got to becareful about carryover. It's
just the opposite. With adaptedsoils, in adapted soils, they
degrade the herbicide morerapidly when the PHS are greater
than about 5.4 where in nonadapted soils, it's just the
opposite. They degrade faster inpH soils less than five or less
(10:40):
than six, and the reason is inthe non adapted soils, the
primary path of degradation isthrough chemical hydrolysis,
where at and the reason that andthe acidic conditions of a debt
or non adapted soils enhance orenhance that Chemical
degradation. Whereas in nonadapted so, or in adapted soils
(11:05):
at low pH, the herbicide bindsmore readily to the soil, and
that makes it unavailable to themicroorganisms. So when you get
into basic soils, the herbicidesmore available, more
bioavailable. Organisms get toit more readily and they degrade
it more rapidly. We have apaper. Well, Jason has a paper
(11:27):
on this whole thing, on theeffect of moisture and
temperature, etc. And as youwould expect, under very dry
conditions, it's all dependenton how active the microorganisms
are so in dry conditions, themicroorganisms are depressed,
and so you'll have longercarryover or more less rates of
(11:49):
degradation. Would you agreewith that Tom?
Tom Mueller (11:53):
yeah, I think it depends on the situation. The pH
factor is the way you describethat as correct, and I'm at a
paper on that exact topic.Another thing is, even if
moisture is present, a lower pHis disfavor bacteria and flavors
fungi. I mean, like, really lowpH it's like less than five,
like you said, and higher PHSfavor bacteria. So that's a
(12:15):
factor too independent of thesoil moisture status. But yeah,
I think, I think you're exactlycorrect. So did you want me to
try to expound on that littlebit? Are you good to go Dale?
Dale Shaner (12:28):
no, that's fine. You can expound on it, because I
didn't say anything about soiltextures or anything like that.
Tom Mueller (12:36):
Yeah I'm gonna just, I'm just gonna try to
cover a really big project wedid. And I agree with Alyssa,
but you know, even under verydry conditions during the corn
growing, seed is Dr Steckel, andI noticed that there was very
seldom any injury. The next yearwhen Atrazine was using corn the
previous year, I also noticedthat I was not alone, that weed
control was not as good fromAtrazine. Basically all the
(12:57):
time. It just seemed like theAtrazine was not working as
well, so I conducted a researchproject to determine how
widespread Atrazine enhanceddegradation was. And if we got
time, I'm just going to read allthe cooperators that I had. And
the reason I'm doing this is toshow you when we're talking
about the breadth of the PHS andthe soil textures and
(13:18):
everything, I just so we hadLarry Steckel out of Tennessee,
Sharon clay, South Dakota State,Mike Owen, Iowa State, Bill Kern
Penn State, Randall curry,Kansas State, Bob Scott,
Arkansas, Christie Sprague,Michigan State, Dan Stevenson
and Donnie Miller. LouisianaState, Eric prosco, Georgia,
James gricker, Texas, A and MJim Martin, Kentucky. Jason
(13:39):
crooks was done on study.Mississippi State. Kevin Bradley
at Missouri. Mark Bernards inWestern Illinois. Peter Daltrey,
Texas, tech, Stephen knevik inNebraska. Vince Davis,
Wisconsin. Bob Klein Nebraska.And then I had, I had studies in
there too. So I understand thattook a little time to read all
those names and everything, butI just wanted to share how
widespread our samples were fromthe United States, and so we
(14:03):
when it comes to textures andPHS and all that, we had a
really strong data set. In fact,there were, and what we did was
to use your terminology, adaptedand non adapted. We call them
history and no history soils.But each cooperator would get a
history soil which was easy tofind, and then they would find
as close to possible, a nonhistory soil, which was
(14:24):
sometimes difficult to find. Andwe defined history as five years
or more, and Dale's alluded tothat, but and realizing that
some of these fields havedecades of atrazine use, I mean,
not five years. So that's how wedid the study we did, and then
we took those soils, and we'rereally sampling the microbial
population in the soils, to behonest with you, that's really
what we're sampling. And then wedid a lab assay. We fortified
(14:47):
all those soils with a knownamount of Atrazine, let them
degrade and run the standardcurves on on all that. So it was
a massive study. We had 60different comparisons, and it
was like one. 1856, samples, andso it's a really strong data
set. So the take home messageis, what's the effects of
(15:11):
texture? There's no effectivetexture. What is the effective
pH? There's no effective pHbecause the enhancement is so
pronounced, you always haveenhancement, or you always have
rapid degradation. So eitherway, you're not having any
actually persistence. So that'skind of like, you know, and
we're not, we're not, I'm not inall saying that if you're
(15:31):
completely dry immediately afterapplication, you're not going to
have slower degradation becausethere's no microbial growth. Dr
Shaner is exactly correct onthat.
Dale Shaner (15:39):
I can kind of add to that, because I did a study
with Professor down in Floridawith very, very high organic
acid organic matter soils inFlorida, and in those cases in
sugarcane, we compared Atrazineand metribuzin degradation, and
there was enhanced Atrazinedegradation in those very high
(16:02):
organic matter soil. So thatreally supports what Tom just
said that soil texture reallyhas little effect on how fast
the herbicide degrades.
Sarah Lancaster (16:13):
So Tom, I pulled this paper that you
talked about with all thedifferent locations. It looks
like you did this work in 2017.Is when it got published?
Tom Mueller (16:23):
It was published in '17. It was the samples were
collected in '14, and thesamples were running '14 to '15.
Sarah Lancaster (16:30):
So my question you've got in your your site,
your location summary for youryour table of all that you do
have the different numbers ofyears of history of application.
Did, I don't think you reportedthat in the paper. Did you look
and see if there were any likebreak points in those years of
(16:52):
application, as far as the rateof degradation, or anything
about the microbial community?
Tom Mueller (16:58):
Yeah, I think I understand the table you're
looking at, and I've got thefigures in front of me. Number
one, when you're working with awide variety of cooperators, to
say that when they said fiveyears of Atrazine use, or 10
years of Atrazine use, orwhatever it was, I think that
may not be the most reliableestimate of the actual history
(17:19):
of the Atrazine use. Okay,that's so and because a lot of
these are not taken by the factthat their staff, their farmers,
their consultants, I mean, it'sit was, I was really proud of
the data set that we had. Andreally, if you've got that paper
ahead of you, if you look atfigure one on the paper, which I
think was the most salientfigure, it basically shows
(17:40):
everywhere. The half lives arealways either short or the
enhancement is very pronounced.Okay, that's kind of when I when
I kind of looked at the data.I'm not sure. I'm probably not.
I'm not speaking to yourquestion, Sarah, so you want to
re ask it again, I don't think Ianswered your question.
Sarah Lancaster (17:58):
Did you try to tease out the effect of time,
like if we were to tell aperson. So if I'm giving
recommendations, I can easilyhear a farmer asking, well, at
what point do I need to worryabout enhanced degradation if
I've haven't applied well, twoquestions, two versions of this,
right? So let's say I've appliedAtrazine for five years. Is that
(18:19):
kind of the the tipping point?Or is it three years? Is it 15
years? Conversely, if I have along rotation, let's say I
rotate away from corn, does thatmicrobial community revert back
and kind of lose that abilityfor enhanced degradation?
Tom Mueller (18:38):
In answer to your first question, we did a
controlled study where we did0,1,2,3,4,5, years, and it was
basically five years. If you gofive years, you get the
enhancement. So basically theanswer, we did a separate study,
not on this PMS paper, but itwas basically after five years.
But that's cheating, because Ihad a pre and a post, so I had
10 applications. Okay, so that'sthat's kind of cheating. The
(19:01):
other thing is, although I haveno data on this statement, I'm
going to say it with greatconfidence, once you have the
enhancement, it's there forever,because there's no fitness
penalty that would favor otherorganisms that would not have
the enhancement. And there is atremendous amount of literature
(19:21):
in the microbial community, notthe microbial community, the
scientific community aboutAtrazine degradation and what
genes do this. And they'vereally spent a lot of effort on
there, because the governmentspent a lot of money figuring
all this out. And so I don'tthink the enhancement you can
you cannot undo the enhancement.I don't think. And that is
(19:42):
paralleled by the agronomicobservations that even if you
stay out of corn for five yearsand you come back the atrazine
still doesn't work very well. Sothat's, that's, that's my
observation on that. Dale, whatdo you think Dale?
Dale Shaner (19:55):
yeah, I would agree on one of the first papers I
wrote with Jason. Uh. He madeit, he said that, or he thought,
looking at the data we had atthe time, that if you, if you
rotated away for over fiveyears, you kind of extended the
life. And I did studies onvarious soils where I don't
(20:16):
think I ever published it, but Ilooked at soils that at the
beginning. I took samples at thebeginning of the year, and then
through the year, and in onecase where they had not applied
Atrazine for about five years,and when I first took a sample
of that soil, the rate ofdegradation was fairly slow, but
(20:37):
within two weeks, it had gottenback to what had been before. So
it just took a little while forthat Atrazine enhancement to go
on. And I remember one paper Iread, I think it came out of
Europe, where they concludedthat the genes, the bacterial
genes that degrade Atrazine,it's about four genes that are
(21:01):
all together are actually on aplasmid, and that the
microorganisms will if theydon't see Atrazine, they will
shed that plasmid, but it'sstill in the soil, and as soon
as Atrazine appears, they willtake that plasmid back up and
start using it again. So it'slike it's just what Tom said,
(21:22):
once you have Atrazinedegradation, you'll probably
have it forever. I had one soilin eastern Colorado where they
had gone organic about 30 yearsbefore. They had used Atrazine
prior to that, but they had beengone organic for 30 years, so
they had not used any Atrazine,and in those soils, I did not
(21:46):
find enhanced degradation, butthat's a pretty long time for
farmers stay out of it. So Iagree with what Tom saying is
that once you have it, you mightas well assume you're always
going to have it. You might slowit down a little bit, but it's
really probably not going tomake much of an effect.
Alyssa Essman (22:08):
So I guess the next question here, I think you
guys have really laid thegroundwork for helping us
understand this process. Butwhat are the implications of
enhanced degradation for weedmanagement in our cropping
systems?
Dale Shaner (22:21):
Well, you, yeah, I'll go first. Tom said it is
farmers. If they're depending onAtrazine to give them long term
weed control, they're not goingto get it. They got to start
treating it as a short residual.So if they put it down pre
plant, they're going to getmaybe three weeks, four weeks at
(22:43):
most, depending on what ratethey use, if they're going to be
in that situation, they'd almosthave to do a split application.
I think the label needs to bedrastically changed, because
they have limits on how muchatrazine can be applied, and
they have limits on followcrops. I got a call once from a
(23:08):
farmers down in Texas. They hadapplied Atrazine the year before
they wanted to plant followed upwith a sensitive follow crop.
They wanted to know if theyneeded to worry, and so I had
them send me soils. There was noAtrazine in the soils that had
enhanced degradation. And I toldthem, Well, I'm not going to
tell you to go against thelabel, but there's no Atrazine
(23:29):
in the soil, so I wouldn't worryabout it. And so that's, that's
what's going to happen. The moreharder to control weeds like
prickly sida, Morningglory, etc.You can't depend on Atrazine to
control it, because it's justnot going to stay a lot round
long enough. So for farmerstrying to use Atrazine, they
(23:52):
just have to know that this is ashort residual herbicide. You
may get two or three weeks maxweed control, and then it's
going to be gone and or soonerthan that, and so you need to
start mixing it with otherherbicides. And it also applies
to other triazine symmetricaltriazines, the proposes the
simazines, those also show rapiddegradation. Metribuzin,
(24:18):
interestingly, does not, atleast not in my hands. Maybe Tom
has got different experiences.Experience. Hexazazone does not
because they're asymmetrical.They're they're not symmetrical
triazine, so they're notdegraded in the same way. So
that's, you know, I think forfarmers, you just have to tell
them, Don't depend on Atrazineto give you the weed control you
(24:38):
used to think you're used towhat?
Tom Mueller (24:42):
Yeah, I agree with that 100% so just the weed
control is not going to be thesame. Rotation of crops will
probably not be damaged byAtrazine residues. Since the
Atrazine is being applied, isbeing degraded, a point on that
too is all the registrationswhenever you do a triazine study
for re registration. Okay, theEPA mandates that the
(25:03):
registrants do it on soils withno previous Atrazine use. So
they are dictating to theregistrant, when they do a
study, to pick a soil that'scompletely different from where
it's almost always being used inthe real United States use
scenario. The other thing is,atrazine has post activity, so
(25:23):
it's used as a synergist to theHPPD inhibiting herbicides. It's
unchanged by the Atrazine soilbehavior. Everybody. It doesn't
matter if it's degraded or not.Also, as Dale said, delaying the
Atrazine application of soil aslong as possible, which is
what's happening with some ofthe like helix GT and all those
things. For example, an earlypost treatment would move the
Atrazine residual later in theseason to provide more, longer
(25:46):
lasting control. So that wouldbe another aspect to it. And the
crop safety of Atrazine post isfine. I mean, unless you get a
lot, but yeah, and I don't, andI don't think there's any way
there. I mean, I agreeagronomically with what Dale fan
say is saying about raising therates, but Atrazine is one of
those things that's under underduress because of the
(26:06):
environmental loadings and soforth. So I don't, although
agronomically, that'd be true,that's not going to happen. I
Dale Shaner (26:11):
think, yeah, I think one of the things that
don't
Jason did was look at thevarious models of dissipation,
and if you look at any of themodels on Atrazine dissipation
using the standard coefficients,it's going to way overestimate
(26:31):
how long Atrazine is going to bethere. The models are wrong
because they don't have theright parameters in there. And
it has to do I've looked at theleaching of Atrazine under
different cropping situations.And if you're in any kind of
situation has corn in it,atrazine really doesn't leach
because it just degrades toorapidly, whereas if you look at
(26:55):
it under a non adapted soil, youcan show quite a bit of leaching
with it. So again, the modelsare wrong. The EPA needs to be
educated that this Atrazinedegradation, enhanced Atrazine
degradation, is a factor acrossnot just the US, but across the
(27:17):
whole world. And when they'relabeling it. It's really not the
same herbicide that they areused to. And like Tom said, I
would, I would really push postearly post applications or
whatever will give you thelongest residual of Atrazine and
use something else Pre.
Alyssa Essman (27:40):
This brings me to kind of an interesting question
here. I think that you'veaddressed a little bit. But how
do you think these findingsshould influence the use of
these herbicides and some of theregulations I know Tom you
mentioned, this is one of those.You know, atrazine specifically
is one of those herbicides thatis under a lot of scrutiny. So I
guess, what do you imagine theprocess looking like for
Tom Mueller (28:00):
I like to echo what, what Dale's saying about,
incorporating
you know, trying to get the EPAto maybe perhaps use a different
perspective on it. But one wayto look at it is the impact of
environmental loadings in thesurface water probably will not
be affected by the Atrazineenhanced degradation. And I'll
tell you why it's a littledifferent, little different
scenario, if most of theAtrazine is coming off of the
(28:22):
field before it's associatedwith the soil microbes. And this
often happens, you spray theherbicide on the soil, you get a
torrential rainfall, and ifthere's any off target movement
in that surface overland flow,then it doesn't really matter
how quickly the Atrazine isdegraded, because it never gets
to the soil to start with.Therefore, from one perspective,
(28:43):
the surface water loadings arenot largely affected by the
Atrazine enhanced degradation.The surface water loadings may
not be I agree completely withDale Shaner about the subsurface
of the leaching. It doesn't getanywhere because it's degraded
in a matter of days. And all themodels and I, you know, would do
modeling work, not as good asJason Cruz, by the way, but they
(29:03):
always overestimate leaching bya factor of 1000 or something.
And it's mind boggling how wrongthe models are. So that's kind
of my thoughts on the surfaceload, because the reality is in
there's parts of Iowa theAtrazine is getting into the
rivers. I mean, they measure it.The USGS does a finance a very
good job of finding Atrazine,quantifying in the barbers. So
(29:27):
it's getting there, even thoughthe enhancement of degradation,
I would make the case, isactually ubiquitous all
throughout Iowa, in thosewatersheds. But it just it
doesn't affect the enhanceddegradation. Doesn't affect it
because it doesn't get to thesoil, it washes off before it
gets into the ability of thesoil to degrade it. So that's
one way of looking at it
Alyssa Essman (29:49):
that's really helpful one. So I guess one
other question that came up forme is, when you're working with
growers and kind of addressingthis issue, how do you tease
apart. Maybe, you know what mypattern wise, appear to be
resistance, but maybe it'sactually this enhanced
degradation. And you know someof the conversations around that
topic,
Dale Shaner (30:13):
well, that is a problem, and I think Tom touched
on it. I know in sugarcane, theythought they had triazine
resistant Morning Glory, and Iremember testing the soils, and
it showed this enhanceddegradation and and they
realized, because when theytested the Morningglory, that
(30:33):
they thought was triazineresistant, it wasn't. They
tested it, it wasn't resistant.So what they thought was
resistance was actually theenhanced degradation. How do you
tell farmers that? That's a goodquestion. I would one look at
the history of triazine use, andhow is this is the pattern of
(30:55):
weeds in the field uniform, ordoes it occur in spots? Because
that's one of the first signsthat you're getting resistance.
Is that the first sign ofresistance is that weeds will
occur in at least initially.Will we occur in clumps? Whereas
(31:17):
if you had enhanced degradation,it would probably be over the
whole field, uniformly sent overthe whole field. So that would
be one thing I would look for.Tom probably has, he has fairly
more experience than that. Butthat's what I would do, is, how
do you tell them? Well, one, letthem know that this happens. Ask
them, Is it, are there otherweeds in that field that are not
(31:39):
being controlled? And if thereare, then it's probably not
resistance, because withresistance, it's usually only
one species. You don't get itacross multiple species, at
least all at the same time. Andso I would look at the pattern
of pattern of weeds. I wouldlook at our other weeds being
controlled. Is it a weed thatyou've always had problems
(32:03):
controlling with Atrazine, likethe morningglories, the prickly
sida is some of the other weeds.Are they being? Were they
controlled in the past, and notnow? But again? What's the
pattern of the weeds in thefield? What do you think Tom?
Tom Mueller (32:17):
I would really echo everything, but what you're
saying, Dale, really nothing toadd, except perhaps that the
farmers kind of already knowthat Atrazine isn't what it was
at least 30-40, years ago, therewas a time when I was very
young, back in like 1905 maybe1910 something like that, when
Atrazine was new, you would putdown a bicep II this bicep Pre
(32:40):
and that was it. I mean, thatwas there was no post emergence.
Now, granted, people werecultivating, they were doing
this thing called Walkingfields. I mean, I know that's
kind of like never going tohappen again, but so you've put
down a pre cultivate corn once,and you're done. Okay. So it's
just not that way. Now, with thesize of farms, there's no
cultivation at all. There's nomechanical control at all. So
(33:02):
that's a very big change fromhistorical perspectives. And
everybody's coming back with apost and so and you know, 25
years ago, the post cleanedeverything up perfectly, and now
that's just not the way it isanymore. But I would, I would
just echo what Dale saying onthat. But I think the farmers,
if they're going corn or sugarcane or grain circle, they
understand the Atrazine isn'twhat it was several decades ago.
Sarah Lancaster (33:26):
I was intrigued by Dale's comments earlier about
the relationship betweennitrogen fertility and how that
it's my interpretation of whatyou said, Dale, is that the
nitrogen, when you have highernitrogen, higher levels of
nitrogen fertility, you havereduced rates of enhanced
degradation. Is that an accuratesummary of what you said way
(33:49):
back at the beginning of thisconversation?
Dale Shaner (33:52):
Well, that's true in the laboratory. Jason
followed this up with a fieldstudy in Mississippi with
enhanced fields that areadapted. And he found that using
the usual amounts of like 150pounds per acre of nitrogen
really had minimal effect on howlong it enhanced the persistence
(34:17):
of Atrazine. So, I mean, it's alaboratory phenomenon, but from
a practical standpoint, and fromhis studies, he would have said,
it's probably not a practicalsolution. I did a study with
another person, USDA, looking atbio barriers, where they where
(34:37):
they were, looking at trying toenhance, try nitrogen, leaching
around uh catalogs, and welooked at the effect of that
with Atrazine. And indeed, inthose conditions, we could show
that Atrazine degradation waswas slow, but again, that was
(34:57):
under laboratory conditions.We're trying to give a farmer
recommendation to enhance toincrease their nitrogen. I think
the pollution from nitrogen isway higher than trying to
enhance the persistence ofAtrazine.
Sarah Lancaster (35:13):
So we kind of talked, I guess, a little bit
about some of the weedmanagement workarounds. But is
there anything other thannitrogen that might be any kind
like anything that shows promiseto investigate as a workaround,
from a like a cultural cropmanagement perspective, does
(35:33):
that question make sense Still?
Dale Shaner (35:35):
Yeah, I think it's getting back to just integrated
weed control that we've talkedabout for herbicide resistance
management, for carryover, forother things, you just need to
use an integrated system. Just,I think Tom and I both touched
(35:56):
on that if you're going to usethe triazine, use them as late
as possible in the season. Takeadvantage of their post
activity. Go to another preherbicide. I mean, metrobusine
doesn't show the it has its ownproblems, but it doesn't show
the enhanced degradation. Atleast it has them until now that
I know of hexazinone is one thatthis enhanced degradation
(36:21):
doesn't happen. But workingagain with this person who was
doing bio barriers, we tookhexazinone and used soils from
an alfalfa field that had beentreated with it, and we were
able actually to induce theenhanced degradation in about
six weeks. So every herbicidehas the potential of developing
(36:45):
or, you know, selecting for theright microorganisms. But any
selection pressure on theenvironment, you're going to
start selecting for things. Yougive the microorganisms a new
energy source, they're going towork hard to take, you know,
take advantage of it, and sousing rotations of herbicides
doing everything we talk aboutintegrative management, that's
(37:08):
the that's going to be the key.Don't depend on any one
herbicide, whether it'sresistance, enhanced degradation
or whatever, to to manage yourweeds. That would be my my story
to the farmers, or myrecommendation. What do you
think? Tom,
Tom Mueller (37:24):
well, I would say, I'd echo those completely. And a
lot of times we need tounderstand that farmers, they
don't wake up and say, Whatherbicide I'm going to use
today? I mean, it's they've got100 other things to do. And so,
you know, looking backwards atthe history of Ronald Frady, one
of the great successes was itwas so extremely simple. I mean,
that's one of the factors. Andso when you go when you talk
(37:45):
about integrated weedmanagement, which is what we
have to do, it just makes lifemore complicated. And so in
answer to your question, if Iwas a young researcher, I mean,
I'm 100 years older than I amnow, I would spend my time in
mechanical weed control, robots,drones, whatever that can kill
weeds without chemicals. Andthis is because sooner or later,
(38:06):
the regulators will try to makechemicals not available. And
this is already happening inEurope, but the governments are
regulating the farmers out ofbusiness. And so I would, I
would visit, you know, when I gotravel, and they'll say, Well,
how do you do such and such? Wecan't use paraquat. We can't use
that chemical. We can't use, Imean, atrazine, I'm not sure. I
think it's banned in Europe. Andthere's, there's not a lot of
(38:27):
maize in Europe anyway, it's nota huge crop like it is here. So,
I mean, yeah, I think there'schemicals in many of the public
is bad. Chemicals are bad, andthe reason they're so extremely
widely used is because they'reso unbelievably effective. It's
like, whenever I have aninfection in my arm, I don't sit
there and say, I'm going to beholistic and not and not put
(38:48):
anything on it. No, I'm going toput some an antibiotic on it
immediately. You know, I'm goingto treat it immediately. And
that's the same thing. So, andit's going to be challenging,
and because I think we allunderstand the regulatory
hurdles are only getting moreexacerbated. So that's a whole
nother. That's a whole notherpodcast. So, but yeah, that's
(39:09):
kind of my thoughts on it. Thegolden days of weed control were
really nice for the farmers, andthose are gone.
Sarah Lancaster (39:16):
I think that's a great segue to your last
question. A question. Alyssa.
Alyssa Essman (39:23):
Okay, so yes, it is Sarah, our final question for
the day. We've been askingguests at the end of our
episodes here this season, isthere a silver bullet, for weed
control.
Tom Mueller (39:34):
You want to go first Dale, or you want me to
Dale Shaner (39:36):
No well I would say, you know, I'm out of the
go?
business now, although I kind ofstay up with it, but no, there
is no silver bullet. I thinkwhat Tom just said, particularly
about the use of robotics andother things, is a promising
future. It needs a lot of work.Is it going to be economical
(39:59):
that. That's going to beremained to be seen. It's not
going to work in all crops. Takelessons from what are the
organic farmers using? They usea lot of cultivation for weed
control. They still have tocontrol the weeds and the use of
robotics, some of the newertechnologies, they're all going
(40:21):
to have their weaknesses,they're all going to have their
strengths. But there is nosilver bullet. People thought it
was with Roundup Ready, and itit was a good ride for 10-15,
years. But, you know, it broke.Everything's going to break if
you depend on it entirely. Sointegrated weed control, using
his new technology that we canyou know, it's some ways I'm
(40:45):
kind of sad I've retired fromWeed Science, because I think
there's a lot of exciting areasto work in out there and and I
hope the young scientists Takeadvantage of that. Tom?
Tom Mueller (41:01):
I agree on a percent, there was a silver
bullet, and unfortunately, acompany made gazillions of
dollars on it. And if they hadnot developed Roundup Ready
corn, and if they had notcompletely squelched the Liberty
Link soybean seed trade, andthat's clearly an antitrust
issue, but not going to sayanything else on that, because
I'm not going to get sued, thenthe glyphosate resistance issues
(41:21):
we now have would be much lessand could possibly have been
largely avoided, at least, ifyou agree with Stephen Powell,
who is a real brilliantresearcher out of Australia, and
he had this double knock theorywhere if you have two modes of
action, you go back and forth,back and forth, you can you'll
go 20, 30,40, years. So yeah, wehad a silver bullet, and we had
the golden age, but no longer.And by the way, it was great for
(41:43):
the farmers while it lasted. SoI'm happy for the farmers, but
we're not there anymore, andthose are historical lessons we
can learn and go forward fromthere. So just a thought, few
thoughts.
Alyssa Essman (41:54):
So thank you both so much for joining us today. We
really enjoyed thisconversation. I want to give you
a quick opportunity. If you haveany social media or a website or
a certain paper you want topoint folks towards, where can
we find more information aboutthis topic? Tom, you want to
start us off?
Tom Mueller (42:10):
Yeah, we have a publication we're very proud of.
It's PB 1580, PB 1580 so if youjust Google PB 1580 that's
University of Tennessee. Weedcontrol recommendations, and
Larry Steckel and the committeewrites that, and that's our we
also have ut crops.com which ismore of a Southern flavor, but
Larry and the group does anexcellent job on that. UT
(42:31):
crops.com
Alyssa Essman (42:34):
thanks Tom. Dale?
Dale Shaner (42:37):
Well, I think I sent you a bunch of papers at
1.1 paper I would recommend isthe review that Jason wrote on
and I don't have it right infront of me, but you should be
able to find it on the agronomicand consequences of enhanced
(42:57):
degradation. It's a very goodreview looks at all the
different application, all thedifferent conditions on where
enhanced degradation has beenfound and factors that affect
it. And if somebody wanted agood background on enhanced
degradation, I would recommendthat particular paper.
Alyssa Essman (43:15):
Awesome. I certainly have that paper. We'll
make sure it gets posted in theshow notes. Thank you both so
much for joining us today. Thankyou to the listeners and our
sponsors, and we hope you'lljoin us next week on the War
Against Weeds podcast.
Thanks for tuning in. Just areminder, you can find this and
(43:36):
other podcasts and resources onthe crop protection network.
This network has a host ofinformation from extension
programs across the US about allthings pest management. We hope
to catch you next week on thewar against weeds podcast.
Music.
Alyssa Essman (00:07):
Welcome back to the war against weeds podcast.
This is Alyssa Essman, WeedScience extension specialist at
The Ohio State. Today I'm joinedby my co host Sarah Lancaster,
Weed Science extensionspecialist at Kansas State. Hey,
Sarah,
Sarah Lancaster (00:19):
howdy, Alyssa.
Alyssa Essman (00:21):
Today, we're joined by two professionals to
talk all about our topic,enhanced degradation of triazine
herbicides. And I think we'vegot two folks who can really
give us some really greatinsight into this topic. So
we've got doctors, Dale Shanerand Tom Mueller. So we want to
give you a second to introduceyourselves and a little bit
about where you're coming fromand what you do? So, Dale, do
(00:42):
you want to start us off andtell us a little bit about
yourself?
Dale Shaner (00:46):
Well, I am a weed scientist. I worked in the area
for about 40 years. I am nowretired, living in the mountains
in Colorado. In my career, Iworked on the imidazolone and
herbicides, and I also did a lotof work on herbicide soil
interactions while I worked forUSDA for about 11 years before I
(01:08):
retired.
Alyssa Essman (01:10):
Awesome. Well, sounds like you're very well
equipped to help us out withthis information. Tom, where are
you coming from?
Tom Mueller (01:17):
Well, I'm just happy to be here. Just a little
background on myself. I have aBS from Illinois. I work for in
the real world for two years. Ihave a master's from Kentucky, a
PhD from Georgia, a post doc inMississippi for a couple years.
And then I've been at theUniversity of Tennessee for 33
years, and work in the area ofenvironmental fate of herbicides
in soils and in air and water.And I just want to say that the
(01:41):
views expressed by Tom Muellerdo not represent the views of
the University of Tennessee orany other associated group. And
also, this is being taped rightbefore an election. I just want
to say that although I haven'tgiven it yet, I still approve
this message.
Alyssa Essman (01:56):
Fabulous. Okay, so I thought we'd start off with
a little bit of context, becauseI think this is a really
interesting area of work, andI'm curious to know how each of
you, you know, got into this. SoDale, maybe we can start with
you. You know, what interestedyou in this topic?
Dale Shaner (02:16):
Well, I kind of stumbled into it when I joined
USDA, the unit that I wasinvolved with was in precision
agriculture, and I was doing astudy on looking at the effect
of different parts of a field onherbicide behavior in the soil.
(02:36):
And in this particular field, itwas a farmer's field he had
applied Atrazine, and I hadcollected soils from different
parts of the field withdifferent soil characteristics,
and I had collected samples forabout six weeks, and so I was
going to start doing theanalysis. And I first started
(02:58):
looking at Atrazine, and when Itried to measure the levels of
Atrazine, there wasn't anythingthere. And that really puzzled
me. So I thought, Well, maybe hedidn't apply what he thought he
applied. So then I went backthrough the samples, and I
started with the first samplethat I collected right after
application. And indeed, therewas Atrazine there, but then I
(03:20):
had collected over several, youknow, every week for six weeks,
and I started looking goingforward, and after two weeks,
there was no more accuracy. AndI thought, well, maybe my
analysis is wrong or somethingelse. And so then I took the
soils into the lab and did a labstudy and found indeed, that the
(03:41):
half life of Atrazine in the labwas about three days, and the
literature said it should beabout 60 days. And so that's
what started me in the wholething, just trying to understand
what happened, saw this enhanceddegradation, and then looking at
the literature, found out thiswasn't a new phenomenon, and I
worked with a weed scientistfrom USDA in Mississippi, Dr
(04:06):
Krutz, and he had been workingon it for a while, and then we
just went from there.
Alyssa Essman (04:13):
So interesting. I love when it seems like a real
world problem, where you saidyou were working with a farmer's
field and you just happen tonotice this. That's that's kind
of fun. So Tom, how did you getinto this work?
Tom Mueller (04:24):
Well, research on herbicide fading sorrows was
prevalent in many universitiesin the 1980s and 90s, with many
prominent research groupsworking in this area. And I'm
going to consider this sort of ahistorical document. So I made a
list of the folks who used towork in this area. So I'm just
going to read these off. Get PatShea at Nebraska Bill Costco in
Minnesota. Jerry Weber at NorthCarolina State. Terry laby at
(04:45):
Arkansas, although John maticewas a brilliant chemist and
scientist, so really Matisse wasor Matisse was actually the
smart guy there. Morris Merkelat Texas A and M. David Shaw,
Mississippi State. Bill banks atGeorgia. Bill Witt at Kentucky.
Jason Cruz, which Dale isalready. Mentioned, and Dale
Shaner At Colorado. Nowcurrently, there are very few
groups working on herbicide fatein soils. I mean, Tim gray at
(05:06):
Georgia, Travis Gannon in turfin North Carolina State, and me
in Tennessee. And the reason forthis is there's, you know, we
could talk about another time,but I just have always been
looking at it from an agronomicperspective. And so that's what
we'll talk about, it. Why, whenwe get into why we looked at
enhanced degradation was It wassimilar to what Dale was talking
(05:28):
about, except that we werelooking at just in general,
atrazine wasn't working like itwas before. So that's how we got
into the specific topic.
Alyssa Essman (05:37):
Yeah so that's kind of a great segue, talking
about, you know, atrazine wasn'tworking like it was before. Can
you guys kind of walk us throughwhat we mean by enhanced
degradation and kind of lay outthis process for us.
Tom Mueller (05:51):
You wanna go first Dale? You want me to go?
Dale Shaner (05:54):
You can go.
Tom Mueller (05:56):
Okay, well, atrazine was, at one time, the
foundational herbicide use andweed control in corn, grain
sorghum and sugar cane. And itwas also used in many other
situations, but predominantly,most pounds went on field corn.
It was normally appliedimmediately before planting,
immediately after planting.Although it can be used early
post and Dale knows more than Ido. It's a photo system to
inhibitor and all that good modeof action stuff. So it was
(06:20):
basically used on everything.And Atrazine is a triazine
chemical. And I'm not even goingto try to do anything chemically
related to what explaining whata triazine is. All I'm going to
say is that there are nonaturally occurring triazines
from an environmentalperspective. I'm at least, I'm
pretty sure that's true. And if,if that's not true, Dr Shaner
(06:40):
can correct me on that. Sobefore we go any further, let's
discuss exactly what enhancedmicrobial degradation of
chemicals means. If I've got anew chemical and it's introduced
into the soil environment, themicrobes will eventually
determine how to best metabolizeor degrade that new molecule. So
enhanced degradation is by nomeans unique to Atrazine, and
(07:01):
many pesticides have had issueswith rapid degradation after
several years of use soilapplied insecticides such as
carbofuran, the carbamathyoateherbicides, which I don't think
anybody uses anymore, they wouldhave special adjuvants added to
them to discourage the enhancedmicrobial degradation. So that's
that's what's happening. And soif you've got a completely novel
(07:23):
type of chemistry now present inthe soil environment, like a
triazine, it has the chance tobe more persistent to microbial
degradation. So like Dr Shanewas saying when it first came
out, atrazine would last a longtime, 60 days, 70 days, easy.
But now with the enhanceddegradation, it just doesn't
last as long. Does that kind ofintroduce the topic of what
(07:44):
we're talking about?
Alyssa Essman (07:46):
Yeah. Yeah, it does. Thank you, Dale, do you
have any thoughts? And also,could you kind of also classify
these what we call adaptedversus non adapted soils?
Dale Shaner (07:55):
Yeah, we do. I did a lot of work with Jason crutz
on this, and non adapted soilsor soils that have never seen
Atrazine, or have had very, veryfew applications of Atrazine.
And when you look at the halflife of Atrazine in those soils,
you will find that it is verylong, comparable to what was the
(08:20):
norm Prior to the discoverytrizin, adapted soils around 60
days, or maybe a little less,with adapted soils, everything
that I've ever looked at, and Ithink Tom would agree, is our
soils that have had multipleapplications of Atrazine. And as
he said, you know, atrazine wasintroduced in the 50s, and so
(08:43):
it's been used now for about 70years. And it's not too
surprising that soils will willour bacteria in the soil will
evolve to start using this newsource of energy. And in the
case of the triazines, one ofthe main reasons they're using
(09:04):
it is for a nitrogen source,because if you have high
nitrogen, it will inhibit thedegradation of Atrazine. So
adapted and non adaptive justreally means, what's the history
of the soil? Has it seen theseherbicides before? If it has,
then you will likely find thesemicroorganisms that will degrade
(09:25):
it.
Alyssa Essman (09:28):
Yeah. So one other question that comes up
then, when we've had, you know,in Ohio this year, we had a wet
spring and a really droughtysummer, and it seems like we're
getting more and more of theseinteresting weather patterns.
And so I'm curious, you know,how do those environmental
conditions, maybe wet soils anddry soils, but also our field
characteristics, things likesoil pH, kind of influence this
(09:51):
process? Dale, do you want tostart us off on this one?
Dale Shaner (09:54):
Yeah, this is an interesting aspect of these
adapted soils. If you look atthe label. For triazines, prior
to the discovery of thesemicroorganisms that degrade it,
you will see that that they saythat Atrazine persists longer in
high pH soils than in acidicsoils, and so that if you have
(10:17):
high pH soils, you got to becareful about carryover. It's
just the opposite. With adaptedsoils, in adapted soils, they
degrade the herbicide morerapidly when the PHS are greater
than about 5.4 where in nonadapted soils, it's just the
opposite. They degrade faster inpH soils less than five or less
(10:40):
than six, and the reason is inthe non adapted soils, the
primary path of degradation isthrough chemical hydrolysis,
where at and the reason that andthe acidic conditions of a debt
or non adapted soils enhance orenhance that Chemical
degradation. Whereas in nonadapted so, or in adapted soils
(11:05):
at low pH, the herbicide bindsmore readily to the soil, and
that makes it unavailable to themicroorganisms. So when you get
into basic soils, the herbicidesmore available, more
bioavailable. Organisms get toit more readily and they degrade
it more rapidly. We have apaper. Well, Jason has a paper
(11:27):
on this whole thing, on theeffect of moisture and
temperature, etc. And as youwould expect, under very dry
conditions, it's all dependenton how active the microorganisms
are so in dry conditions, themicroorganisms are depressed,
and so you'll have longercarryover or more less rates of
(11:49):
degradation. Would you agreewith that Tom?
Tom Mueller (11:53):
yeah, I think it depends on the situation. The pH
factor is the way you describethat as correct, and I'm at a
paper on that exact topic.Another thing is, even if
moisture is present, a lower pHis disfavor bacteria and flavors
fungi. I mean, like, really lowpH it's like less than five,
like you said, and higher PHSfavor bacteria. So that's a
(12:15):
factor too independent of thesoil moisture status. But yeah,
I think, I think you're exactlycorrect. So did you want me to
try to expound on that littlebit? Are you good to go Dale?
Dale Shaner (12:28):
no, that's fine. You can expound on it, because I
didn't say anything about soiltextures or anything like that.
Tom Mueller (12:36):
Yeah I'm gonna just, I'm just gonna try to
cover a really big project wedid. And I agree with Alyssa,
but you know, even under verydry conditions during the corn
growing, seed is Dr Steckel, andI noticed that there was very
seldom any injury. The next yearwhen Atrazine was using corn the
previous year, I also noticedthat I was not alone, that weed
control was not as good fromAtrazine. Basically all the
(12:57):
time. It just seemed like theAtrazine was not working as
well, so I conducted a researchproject to determine how
widespread Atrazine enhanceddegradation was. And if we got
time, I'm just going to read allthe cooperators that I had. And
the reason I'm doing this is toshow you when we're talking
about the breadth of the PHS andthe soil textures and
(13:18):
everything, I just so we hadLarry Steckel out of Tennessee,
Sharon clay, South Dakota State,Mike Owen, Iowa State, Bill Kern
Penn State, Randall curry,Kansas State, Bob Scott,
Arkansas, Christie Sprague,Michigan State, Dan Stevenson
and Donnie Miller. LouisianaState, Eric prosco, Georgia,
James gricker, Texas, A and MJim Martin, Kentucky. Jason
(13:39):
crooks was done on study.Mississippi State. Kevin Bradley
at Missouri. Mark Bernards inWestern Illinois. Peter Daltrey,
Texas, tech, Stephen knevik inNebraska. Vince Davis,
Wisconsin. Bob Klein Nebraska.And then I had, I had studies in
there too. So I understand thattook a little time to read all
those names and everything, butI just wanted to share how
widespread our samples were fromthe United States, and so we
(14:03):
when it comes to textures andPHS and all that, we had a
really strong data set. In fact,there were, and what we did was
to use your terminology, adaptedand non adapted. We call them
history and no history soils.But each cooperator would get a
history soil which was easy tofind, and then they would find
as close to possible, a nonhistory soil, which was
(14:24):
sometimes difficult to find. Andwe defined history as five years
or more, and Dale's alluded tothat, but and realizing that
some of these fields havedecades of atrazine use, I mean,
not five years. So that's how wedid the study we did, and then
we took those soils, and we'rereally sampling the microbial
population in the soils, to behonest with you, that's really
what we're sampling. And then wedid a lab assay. We fortified
(14:47):
all those soils with a knownamount of Atrazine, let them
degrade and run the standardcurves on on all that. So it was
a massive study. We had 60different comparisons, and it
was like one. 1856, samples, andso it's a really strong data
set. So the take home messageis, what's the effects of
(15:11):
texture? There's no effectivetexture. What is the effective
pH? There's no effective pHbecause the enhancement is so
pronounced, you always haveenhancement, or you always have
rapid degradation. So eitherway, you're not having any
actually persistence. So that'skind of like, you know, and
we're not, we're not, I'm not inall saying that if you're
(15:31):
completely dry immediately afterapplication, you're not going to
have slower degradation becausethere's no microbial growth. Dr
Shaner is exactly correct onthat.
Dale Shaner (15:39):
I can kind of add to that, because I did a study
with Professor down in Floridawith very, very high organic
acid organic matter soils inFlorida, and in those cases in
sugarcane, we compared Atrazineand metribuzin degradation, and
there was enhanced Atrazinedegradation in those very high
(16:02):
organic matter soil. So thatreally supports what Tom just
said that soil texture reallyhas little effect on how fast
the herbicide degrades.
Sarah Lancaster (16:13):
So Tom, I pulled this paper that you
talked about with all thedifferent locations. It looks
like you did this work in 2017.Is when it got published?
Tom Mueller (16:23):
It was published in '17. It was the samples were
collected in '14, and thesamples were running '14 to '15.
Sarah Lancaster (16:30):
So my question you've got in your your site,
your location summary for youryour table of all that you do
have the different numbers ofyears of history of application.
Did, I don't think you reportedthat in the paper. Did you look
and see if there were any likebreak points in those years of
(16:52):
application, as far as the rateof degradation, or anything
about the microbial community?
Tom Mueller (16:58):
Yeah, I think I understand the table you're
looking at, and I've got thefigures in front of me. Number
one, when you're working with awide variety of cooperators, to
say that when they said fiveyears of Atrazine use, or 10
years of Atrazine use, orwhatever it was, I think that
may not be the most reliableestimate of the actual history
(17:19):
of the Atrazine use. Okay,that's so and because a lot of
these are not taken by the factthat their staff, their farmers,
their consultants, I mean, it'sit was, I was really proud of
the data set that we had. Andreally, if you've got that paper
ahead of you, if you look atfigure one on the paper, which I
think was the most salientfigure, it basically shows
(17:40):
everywhere. The half lives arealways either short or the
enhancement is very pronounced.Okay, that's kind of when I when
I kind of looked at the data.I'm not sure. I'm probably not.
I'm not speaking to yourquestion, Sarah, so you want to
re ask it again, I don't think Ianswered your question.
Sarah Lancaster (17:58):
Did you try to tease out the effect of time,
like if we were to tell aperson. So if I'm giving
recommendations, I can easilyhear a farmer asking, well, at
what point do I need to worryabout enhanced degradation if
I've haven't applied well, twoquestions, two versions of this,
right? So let's say I've appliedAtrazine for five years. Is that
(18:19):
kind of the the tipping point?Or is it three years? Is it 15
years? Conversely, if I have along rotation, let's say I
rotate away from corn, does thatmicrobial community revert back
and kind of lose that abilityfor enhanced degradation?
Tom Mueller (18:38):
In answer to your first question, we did a
controlled study where we did0,1,2,3,4,5, years, and it was
basically five years. If you gofive years, you get the
enhancement. So basically theanswer, we did a separate study,
not on this PMS paper, but itwas basically after five years.
But that's cheating, because Ihad a pre and a post, so I had
10 applications. Okay, so that'sthat's kind of cheating. The
(19:01):
other thing is, although I haveno data on this statement, I'm
going to say it with greatconfidence, once you have the
enhancement, it's there forever,because there's no fitness
penalty that would favor otherorganisms that would not have
the enhancement. And there is atremendous amount of literature
(19:21):
in the microbial community, notthe microbial community, the
scientific community aboutAtrazine degradation and what
genes do this. And they'vereally spent a lot of effort on
there, because the governmentspent a lot of money figuring
all this out. And so I don'tthink the enhancement you can
you cannot undo the enhancement.I don't think. And that is
(19:42):
paralleled by the agronomicobservations that even if you
stay out of corn for five yearsand you come back the atrazine
still doesn't work very well. Sothat's, that's, that's my
observation on that. Dale, whatdo you think Dale?
Dale Shaner (19:55):
yeah, I would agree on one of the first papers I
wrote with Jason. Uh. He madeit, he said that, or he thought,
looking at the data we had atthe time, that if you, if you
rotated away for over fiveyears, you kind of extended the
life. And I did studies onvarious soils where I don't
(20:16):
think I ever published it, but Ilooked at soils that at the
beginning. I took samples at thebeginning of the year, and then
through the year, and in onecase where they had not applied
Atrazine for about five years,and when I first took a sample
of that soil, the rate ofdegradation was fairly slow, but
(20:37):
within two weeks, it had gottenback to what had been before. So
it just took a little while forthat Atrazine enhancement to go
on. And I remember one paper Iread, I think it came out of
Europe, where they concludedthat the genes, the bacterial
genes that degrade Atrazine,it's about four genes that are
(21:01):
all together are actually on aplasmid, and that the
microorganisms will if theydon't see Atrazine, they will
shed that plasmid, but it'sstill in the soil, and as soon
as Atrazine appears, they willtake that plasmid back up and
start using it again. So it'slike it's just what Tom said,
(21:22):
once you have Atrazinedegradation, you'll probably
have it forever. I had one soilin eastern Colorado where they
had gone organic about 30 yearsbefore. They had used Atrazine
prior to that, but they had beengone organic for 30 years, so
they had not used any Atrazine,and in those soils, I did not
(21:46):
find enhanced degradation, butthat's a pretty long time for
farmers stay out of it. So Iagree with what Tom saying is
that once you have it, you mightas well assume you're always
going to have it. You might slowit down a little bit, but it's
really probably not going tomake much of an effect.
Alyssa Essman (22:08):
So I guess the next question here, I think you
guys have really laid thegroundwork for helping us
understand this process. Butwhat are the implications of
enhanced degradation for weedmanagement in our cropping
systems?
Dale Shaner (22:21):
Well, you, yeah, I'll go first. Tom said it is
farmers. If they're depending onAtrazine to give them long term
weed control, they're not goingto get it. They got to start
treating it as a short residual.So if they put it down pre
plant, they're going to getmaybe three weeks, four weeks at
(22:43):
most, depending on what ratethey use, if they're going to be
in that situation, they'd almosthave to do a split application.
I think the label needs to bedrastically changed, because
they have limits on how muchatrazine can be applied, and
they have limits on followcrops. I got a call once from a
(23:08):
farmers down in Texas. They hadapplied Atrazine the year before
they wanted to plant followed upwith a sensitive follow crop.
They wanted to know if theyneeded to worry, and so I had
them send me soils. There was noAtrazine in the soils that had
enhanced degradation. And I toldthem, Well, I'm not going to
tell you to go against thelabel, but there's no Atrazine
(23:29):
in the soil, so I wouldn't worryabout it. And so that's, that's
what's going to happen. The moreharder to control weeds like
prickly sida, Morningglory, etc.You can't depend on Atrazine to
control it, because it's justnot going to stay a lot round
long enough. So for farmerstrying to use Atrazine, they
(23:52):
just have to know that this is ashort residual herbicide. You
may get two or three weeks maxweed control, and then it's
going to be gone and or soonerthan that, and so you need to
start mixing it with otherherbicides. And it also applies
to other triazine symmetricaltriazines, the proposes the
simazines, those also show rapiddegradation. Metribuzin,
(24:18):
interestingly, does not, atleast not in my hands. Maybe Tom
has got different experiences.Experience. Hexazazone does not
because they're asymmetrical.They're they're not symmetrical
triazine, so they're notdegraded in the same way. So
that's, you know, I think forfarmers, you just have to tell
them, Don't depend on Atrazineto give you the weed control you
(24:38):
used to think you're used towhat?
Tom Mueller (24:42):
Yeah, I agree with that 100% so just the weed
control is not going to be thesame. Rotation of crops will
probably not be damaged byAtrazine residues. Since the
Atrazine is being applied, isbeing degraded, a point on that
too is all the registrationswhenever you do a triazine study
for re registration. Okay, theEPA mandates that the
(25:03):
registrants do it on soils withno previous Atrazine use. So
they are dictating to theregistrant, when they do a
study, to pick a soil that'scompletely different from where
it's almost always being used inthe real United States use
scenario. The other thing is,atrazine has post activity, so
(25:23):
it's used as a synergist to theHPPD inhibiting herbicides. It's
unchanged by the Atrazine soilbehavior. Everybody. It doesn't
matter if it's degraded or not.Also, as Dale said, delaying the
Atrazine application of soil aslong as possible, which is
what's happening with some ofthe like helix GT and all those
things. For example, an earlypost treatment would move the
Atrazine residual later in theseason to provide more, longer
(25:46):
lasting control. So that wouldbe another aspect to it. And the
crop safety of Atrazine post isfine. I mean, unless you get a
lot, but yeah, and I don't, andI don't think there's any way
there. I mean, I agreeagronomically with what Dale fan
say is saying about raising therates, but Atrazine is one of
those things that's under underduress because of the
(26:06):
environmental loadings and soforth. So I don't, although
agronomically, that'd be true,that's not going to happen. I
Dale Shaner (26:11):
think, yeah, I think one of the things that
don't
Jason did was look at thevarious models of dissipation,
and if you look at any of themodels on Atrazine dissipation
using the standard coefficients,it's going to way overestimate
(26:31):
how long Atrazine is going to bethere. The models are wrong
because they don't have theright parameters in there. And
it has to do I've looked at theleaching of Atrazine under
different cropping situations.And if you're in any kind of
situation has corn in it,atrazine really doesn't leach
because it just degrades toorapidly, whereas if you look at
(26:55):
it under a non adapted soil, youcan show quite a bit of leaching
with it. So again, the modelsare wrong. The EPA needs to be
educated that this Atrazinedegradation, enhanced Atrazine
degradation, is a factor acrossnot just the US, but across the
(27:17):
whole world. And when they'relabeling it. It's really not the
same herbicide that they areused to. And like Tom said, I
would, I would really push postearly post applications or
whatever will give you thelongest residual of Atrazine and
use something else Pre.
Alyssa Essman (27:40):
This brings me to kind of an interesting question
here. I think that you'veaddressed a little bit. But how
do you think these findingsshould influence the use of
these herbicides and some of theregulations I know Tom you
mentioned, this is one of those.You know, atrazine specifically
is one of those herbicides thatis under a lot of scrutiny. So I
guess, what do you imagine theprocess looking like for
Tom Mueller (28:00):
I like to echo what, what Dale's saying about,
incorporating
you know, trying to get the EPAto maybe perhaps use a different
perspective on it. But one wayto look at it is the impact of
environmental loadings in thesurface water probably will not
be affected by the Atrazineenhanced degradation. And I'll
tell you why it's a littledifferent, little different
scenario, if most of theAtrazine is coming off of the
(28:22):
field before it's associatedwith the soil microbes. And this
often happens, you spray theherbicide on the soil, you get a
torrential rainfall, and ifthere's any off target movement
in that surface overland flow,then it doesn't really matter
how quickly the Atrazine isdegraded, because it never gets
to the soil to start with.Therefore, from one perspective,
(28:43):
the surface water loadings arenot largely affected by the
Atrazine enhanced degradation.The surface water loadings may
not be I agree completely withDale Shaner about the subsurface
of the leaching. It doesn't getanywhere because it's degraded
in a matter of days. And all themodels and I, you know, would do
modeling work, not as good asJason Cruz, by the way, but they
(29:03):
always overestimate leaching bya factor of 1000 or something.
And it's mind boggling how wrongthe models are. So that's kind
of my thoughts on the surfaceload, because the reality is in
there's parts of Iowa theAtrazine is getting into the
rivers. I mean, they measure it.The USGS does a finance a very
good job of finding Atrazine,quantifying in the barbers. So
(29:27):
it's getting there, even thoughthe enhancement of degradation,
I would make the case, isactually ubiquitous all
throughout Iowa, in thosewatersheds. But it just it
doesn't affect the enhanceddegradation. Doesn't affect it
because it doesn't get to thesoil, it washes off before it
gets into the ability of thesoil to degrade it. So that's
one way of looking at it
Alyssa Essman (29:49):
that's really helpful one. So I guess one
other question that came up forme is, when you're working with
growers and kind of addressingthis issue, how do you tease
apart. Maybe, you know what mypattern wise, appear to be
resistance, but maybe it'sactually this enhanced
degradation. And you know someof the conversations around that
topic,
Dale Shaner (30:13):
well, that is a problem, and I think Tom touched
on it. I know in sugarcane, theythought they had triazine
resistant Morning Glory, and Iremember testing the soils, and
it showed this enhanceddegradation and and they
realized, because when theytested the Morningglory, that
(30:33):
they thought was triazineresistant, it wasn't. They
tested it, it wasn't resistant.So what they thought was
resistance was actually theenhanced degradation. How do you
tell farmers that? That's a goodquestion. I would one look at
the history of triazine use, andhow is this is the pattern of
(30:55):
weeds in the field uniform, ordoes it occur in spots? Because
that's one of the first signsthat you're getting resistance.
Is that the first sign ofresistance is that weeds will
occur in at least initially.Will we occur in clumps? Whereas
(31:17):
if you had enhanced degradation,it would probably be over the
whole field, uniformly sent overthe whole field. So that would
be one thing I would look for.Tom probably has, he has fairly
more experience than that. Butthat's what I would do, is, how
do you tell them? Well, one, letthem know that this happens. Ask
them, Is it, are there otherweeds in that field that are not
(31:39):
being controlled? And if thereare, then it's probably not
resistance, because withresistance, it's usually only
one species. You don't get itacross multiple species, at
least all at the same time. Andso I would look at the pattern
of pattern of weeds. I wouldlook at our other weeds being
controlled. Is it a weed thatyou've always had problems
(32:03):
controlling with Atrazine, likethe morningglories, the prickly
sida is some of the other weeds.Are they being? Were they
controlled in the past, and notnow? But again? What's the
pattern of the weeds in thefield? What do you think Tom?
Tom Mueller (32:17):
I would really echo everything, but what you're
saying, Dale, really nothing toadd, except perhaps that the
farmers kind of already knowthat Atrazine isn't what it was
at least 30-40, years ago, therewas a time when I was very
young, back in like 1905 maybe1910 something like that, when
Atrazine was new, you would putdown a bicep II this bicep Pre
(32:40):
and that was it. I mean, thatwas there was no post emergence.
Now, granted, people werecultivating, they were doing
this thing called Walkingfields. I mean, I know that's
kind of like never going tohappen again, but so you've put
down a pre cultivate corn once,and you're done. Okay. So it's
just not that way. Now, with thesize of farms, there's no
cultivation at all. There's nomechanical control at all. So
(33:02):
that's a very big change fromhistorical perspectives. And
everybody's coming back with apost and so and you know, 25
years ago, the post cleanedeverything up perfectly, and now
that's just not the way it isanymore. But I would, I would
just echo what Dale saying onthat. But I think the farmers,
if they're going corn or sugarcane or grain circle, they
understand the Atrazine isn'twhat it was several decades ago.
Sarah Lancaster (33:26):
I was intrigued by Dale's comments earlier about
the relationship betweennitrogen fertility and how that
it's my interpretation of whatyou said, Dale, is that the
nitrogen, when you have highernitrogen, higher levels of
nitrogen fertility, you havereduced rates of enhanced
degradation. Is that an accuratesummary of what you said way
(33:49):
back at the beginning of thisconversation?
Dale Shaner (33:52):
Well, that's true in the laboratory. Jason
followed this up with a fieldstudy in Mississippi with
enhanced fields that areadapted. And he found that using
the usual amounts of like 150pounds per acre of nitrogen
really had minimal effect on howlong it enhanced the persistence
(34:17):
of Atrazine. So, I mean, it's alaboratory phenomenon, but from
a practical standpoint, and fromhis studies, he would have said,
it's probably not a practicalsolution. I did a study with
another person, USDA, looking atbio barriers, where they where
(34:37):
they were, looking at trying toenhance, try nitrogen, leaching
around uh catalogs, and welooked at the effect of that
with Atrazine. And indeed, inthose conditions, we could show
that Atrazine degradation waswas slow, but again, that was
(34:57):
under laboratory conditions.We're trying to give a farmer
recommendation to enhance toincrease their nitrogen. I think
the pollution from nitrogen isway higher than trying to
enhance the persistence ofAtrazine.
Sarah Lancaster (35:13):
So we kind of talked, I guess, a little bit
about some of the weedmanagement workarounds. But is
there anything other thannitrogen that might be any kind
like anything that shows promiseto investigate as a workaround,
from a like a cultural cropmanagement perspective, does
(35:33):
that question make sense Still?
Dale Shaner (35:35):
Yeah, I think it's getting back to just integrated
weed control that we've talkedabout for herbicide resistance
management, for carryover, forother things, you just need to
use an integrated system. Just,I think Tom and I both touched
(35:56):
on that if you're going to usethe triazine, use them as late
as possible in the season. Takeadvantage of their post
activity. Go to another preherbicide. I mean, metrobusine
doesn't show the it has its ownproblems, but it doesn't show
the enhanced degradation. Atleast it has them until now that
I know of hexazinone is one thatthis enhanced degradation
(36:21):
doesn't happen. But workingagain with this person who was
doing bio barriers, we tookhexazinone and used soils from
an alfalfa field that had beentreated with it, and we were
able actually to induce theenhanced degradation in about
six weeks. So every herbicidehas the potential of developing
(36:45):
or, you know, selecting for theright microorganisms. But any
selection pressure on theenvironment, you're going to
start selecting for things. Yougive the microorganisms a new
energy source, they're going towork hard to take, you know,
take advantage of it, and sousing rotations of herbicides
doing everything we talk aboutintegrative management, that's
(37:08):
the that's going to be the key.Don't depend on any one
herbicide, whether it'sresistance, enhanced degradation
or whatever, to to manage yourweeds. That would be my my story
to the farmers, or myrecommendation. What do you
think? Tom,
Tom Mueller (37:24):
well, I would say, I'd echo those completely. And a
lot of times we need tounderstand that farmers, they
don't wake up and say, Whatherbicide I'm going to use
today? I mean, it's they've got100 other things to do. And so,
you know, looking backwards atthe history of Ronald Frady, one
of the great successes was itwas so extremely simple. I mean,
that's one of the factors. Andso when you go when you talk
(37:45):
about integrated weedmanagement, which is what we
have to do, it just makes lifemore complicated. And so in
answer to your question, if Iwas a young researcher, I mean,
I'm 100 years older than I amnow, I would spend my time in
mechanical weed control, robots,drones, whatever that can kill
weeds without chemicals. Andthis is because sooner or later,
(38:06):
the regulators will try to makechemicals not available. And
this is already happening inEurope, but the governments are
regulating the farmers out ofbusiness. And so I would, I
would visit, you know, when I gotravel, and they'll say, Well,
how do you do such and such? Wecan't use paraquat. We can't use
that chemical. We can't use, Imean, atrazine, I'm not sure. I
think it's banned in Europe. Andthere's, there's not a lot of
(38:27):
maize in Europe anyway, it's nota huge crop like it is here. So,
I mean, yeah, I think there'schemicals in many of the public
is bad. Chemicals are bad, andthe reason they're so extremely
widely used is because they'reso unbelievably effective. It's
like, whenever I have aninfection in my arm, I don't sit
there and say, I'm going to beholistic and not and not put
(38:48):
anything on it. No, I'm going toput some an antibiotic on it
immediately. You know, I'm goingto treat it immediately. And
that's the same thing. So, andit's going to be challenging,
and because I think we allunderstand the regulatory
hurdles are only getting moreexacerbated. So that's a whole
nother. That's a whole notherpodcast. So, but yeah, that's
(39:09):
kind of my thoughts on it. Thegolden days of weed control were
really nice for the farmers, andthose are gone.
Sarah Lancaster (39:16):
I think that's a great segue to your last
question. A question. Alyssa.
Alyssa Essman (39:23):
Okay, so yes, it is Sarah, our final question for
the day. We've been askingguests at the end of our
episodes here this season, isthere a silver bullet, for weed
control.
Tom Mueller (39:34):
You want to go first Dale, or you want me to
Dale Shaner (39:36):
No well I would say, you know, I'm out of the
go?
business now, although I kind ofstay up with it, but no, there
is no silver bullet. I thinkwhat Tom just said, particularly
about the use of robotics andother things, is a promising
future. It needs a lot of work.Is it going to be economical
(39:59):
that. That's going to beremained to be seen. It's not
going to work in all crops. Takelessons from what are the
organic farmers using? They usea lot of cultivation for weed
control. They still have tocontrol the weeds and the use of
robotics, some of the newertechnologies, they're all going
(40:21):
to have their weaknesses,they're all going to have their
strengths. But there is nosilver bullet. People thought it
was with Roundup Ready, and itit was a good ride for 10-15,
years. But, you know, it broke.Everything's going to break if
you depend on it entirely. Sointegrated weed control, using
his new technology that we canyou know, it's some ways I'm
(40:45):
kind of sad I've retired fromWeed Science, because I think
there's a lot of exciting areasto work in out there and and I
hope the young scientists Takeadvantage of that. Tom?
Tom Mueller (41:01):
I agree on a percent, there was a silver
bullet, and unfortunately, acompany made gazillions of
dollars on it. And if they hadnot developed Roundup Ready
corn, and if they had notcompletely squelched the Liberty
Link soybean seed trade, andthat's clearly an antitrust
issue, but not going to sayanything else on that, because
I'm not going to get sued, thenthe glyphosate resistance issues
(41:21):
we now have would be much lessand could possibly have been
largely avoided, at least, ifyou agree with Stephen Powell,
who is a real brilliantresearcher out of Australia, and
he had this double knock theorywhere if you have two modes of
action, you go back and forth,back and forth, you can you'll
go 20, 30,40, years. So yeah, wehad a silver bullet, and we had
the golden age, but no longer.And by the way, it was great for
(41:43):
the farmers while it lasted. SoI'm happy for the farmers, but
we're not there anymore, andthose are historical lessons we
can learn and go forward fromthere. So just a thought, few
thoughts.
Alyssa Essman (41:54):
So thank you both so much for joining us today. We
really enjoyed thisconversation. I want to give you
a quick opportunity. If you haveany social media or a website or
a certain paper you want topoint folks towards, where can
we find more information aboutthis topic? Tom, you want to
start us off?
Tom Mueller (42:10):
Yeah, we have a publication we're very proud of.
It's PB 1580, PB 1580 so if youjust Google PB 1580 that's
University of Tennessee. Weedcontrol recommendations, and
Larry Steckel and the committeewrites that, and that's our we
also have ut crops.com which ismore of a Southern flavor, but
Larry and the group does anexcellent job on that. UT
(42:31):
crops.com
Alyssa Essman (42:34):
thanks Tom. Dale?
Dale Shaner (42:37):
Well, I think I sent you a bunch of papers at
1.1 paper I would recommend isthe review that Jason wrote on
and I don't have it right infront of me, but you should be
able to find it on the agronomicand consequences of enhanced
(42:57):
degradation. It's a very goodreview looks at all the
different application, all thedifferent conditions on where
enhanced degradation has beenfound and factors that affect
it. And if somebody wanted agood background on enhanced
degradation, I would recommendthat particular paper.
Alyssa Essman (43:15):
Awesome. I certainly have that paper. We'll
make sure it gets posted in theshow notes. Thank you both so
much for joining us today. Thankyou to the listeners and our
sponsors, and we hope you'lljoin us next week on the War
Against Weeds podcast.
Thanks for tuning in. Just areminder, you can find this and
(43:36):
other podcasts and resources onthe crop protection network.
This network has a host ofinformation from extension
programs across the US about allthings pest management. We hope
to catch you next week on thewar against weeds podcast.
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Therapy Gecko
An unlicensed lizard psychologist travels the universe talking to strangers about absolutely nothing. TO CALL THE GECKO: follow me on https://www.twitch.tv/lyleforever to get a notification for when I am taking calls. I am usually live Mondays, Wednesdays, and Fridays but lately a lot of other times too. I am a gecko.