February 26, 2025 • 26 mins
This week Sarah and Joe chat with Dr. Bill Johnson from Purdue University about henbit. They cover why controlling henbit is important and how to manage it in corn and soybean production. Listen now!
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Episode Transcript
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Joe Ikley (00:06):
Welcome back to the war against weeds Podcast. I'm
Joe Ikley, extension weedspecialist at North Dakota State
University. My co host today isDr Sarah Lancaster, down at K
State Sarah, how are you today?
Sarah Lancaster (00:20):
Doing great. mourning the Chiefs lost. We're
recording this the day after theSuper Bowl, so the entire state
is in morning till you get tothe Denver Broncos fans,
Joe Ikley (00:31):
I'm an eight hour drive from any any playoff team,
so found better things to do,but we're not talking football,
although we'll see if anyreferences weave their way in
throughout the course of this.But our guest today is Dr Bill
Johnson at Purdue University,repeat guest. So Bill, welcome
back.
Bill Johnson (00:51):
Thank you for having me. Glad to be back. Good
to see you guys again.
Joe Ikley (00:56):
And in case people haven't listened or don't know
who you are, we should go aheadand have you reintroduce
yourself and all the greatthings you do at Purdue.
Bill Johnson (01:03):
Oh yeah, yeah. Well, yeah, thanks for having me
again. So again, my name is BillJohnson. I'm an Extension weed
scientist. I've been at Purduefor about 23 years, and prior to
that, I was at the University ofMissouri. So I've always had an
extension appointment during myfaculty career. So I've been
able to see a lot of trendschange over the course of time.
(01:24):
And one of the interests I'vealways had in my research
program are interactions betweenweeds and other plant pests.
Those are the things I enjoytalking about as well.
Joe Ikley (01:32):
Well, that's a good segue into why we had you on.
And so I figured I would startwith a question I know you get
about at least March, if notthis time of year every year. So
in eastern the eastern Corn BeltBill, what are all those purple
flowers in the field?
Bill Johnson (01:50):
Yeah, well, good question. So one of the things
that makes many of our no tillfields so colorful in the spring
of the year are weeds that havedifferent colored flowers. So
the purple flowered weeds areactually from the mint family,
and henbit and purple deadnettleare the two most common ones
that we see that that have thesepurple flowers in our no till
(02:12):
fields.
Joe Ikley (02:13):
And so what makes those two mint species common?
Bill Johnson (02:18):
Well, they're winter annual weeds. They
survive in a system where theycan emerge before the crop is
harvested in the fall. So asthese fields retain a little bit
of moisture in the fall from theleaves falling off the crop
plants, these weeds willgerminate very shallow in the
soil. They're able to survivethe harvesting operation because
(02:43):
they're low growing weeds. Theygrow below the cutter height, or
the or the head height for acorn machine. And then they have
the ability to establish on manydifferent soil types. They tend
to like wet soil types inparticular. And then they will
survive the the winter months,and then they resume their life
(03:03):
cycle in the spring, where thepurple flowers typically come
out when, when wheat starts togreen up. And then they'll,
they'll go on and produce seedshortly after that. And then
once the weather temperaturesare typically in the 80s for on
a regular basis, and they, theycan, they senesce and die and
(03:23):
drop their seeds. And theprocess starts all over in the
fall.
Joe Ikley (03:27):
I know you mentioned no till, but have a conventional
tillage. Are they? Are theyoften found in those I mean, I
know there's an easy way toterminate them in that system,
but are you seeing a lot of thehenbit and deadnettle in these
conventional tilled fields aswell.
Bill Johnson (03:42):
Well? Good question. So, yes, we can see
them in conventional till fieldsas well. I think particularly if
you have a situation where we'veharvested the crop early and we
have an extended fall, and wehave good moisture in the fall,
these weeds can, can come up ina situation like that. And you
(04:03):
know, I think if you think aboutour the changes that we have
going on in our climate,regardless of what the causes
are, the Falls tend to be longerthan they were many years ago.
So I think, you know, as we getthat early, early harvest taken
off the field, these weeds havea chance to germinate and
establish in the fall. And Iwill also note that many winter
(04:25):
annual weeds also have theability to germinate and grow in
the spring as well. So I thinkparticularly as we get to the
center and southern part of thecorn and soybean growing areas,
spring starts really early. Andso when we start having these 50
and 60 degree days in February,we can get some spring emergence
(04:46):
of these, these weeds as well.And that can happen, whether
it's in no till or inconventional till.
Joe Ikley (04:52):
Sarah, the focus so far has been the eastern Corn
Belt. But do you deal with themint families there in Kansas?
Sarah Lancaster (05:00):
Not in the western part of the state, sort
of as you drive west alongInterstate 70 in Kansas, you
trade fields of purple forkochia in the fence lines.
That's sort of how you know whenyou're in western Kansas. I
wondered, though, Bill, do youthink it would be maybe
interesting for some of thelisteners to just talk about
(05:21):
some of the differences betweenhenbit and purple deadnettle.
Bill Johnson (05:26):
Yeah, yeah. I think the there, it's very easy
to to confuse them from adistance, they have kind of a
rough leaf texture. When viewedfrom the top, they also have the
purple flowers as well. But ifyou, if you pull the plants up
and hold them side by side, andthere's a lot of good images you
can Google them, and there's alot of good images you can pull
up on the web. Purple deadnettlewill have more of a triangular
(05:50):
shaped leaf, and the leaf willactually have a short petiole
between the leaflet and thestem. And henbit tends to
produce these sort of half moonshaped leaves that tend to stick
almost directly onto the stem.Now both plants will have a
square stem, and that's how wedifferentiate plants that are in
the mint family, but again, veryeasy to confuse them. And if you
(06:14):
pull them up and look at themclosely, then it's pretty easy
to tell them apart. One thingthat we see a lot of as well as
it's rare. It seems like it'sit's somewhat rare to have hand
bit and purple deadnettle in thesame field. We tend to have one
or the other, and it's kind ofrare to have both of them. And I
don't know the biologicalreasoning for that. That's just
(06:34):
been an observation through someof our survey work.
Joe Ikley (06:37):
So besides nerds like us, who like to identify stuff
and get asked these questions,does it matter for management,
which one of the two you have
Bill Johnson (06:46):
no in the in the work that we've done on no till
weeds, that it doesn't matterthe herbicide program for
controlling both is going to bethe same.
Joe Ikley (06:54):
And so I'm also partly asking so, I mean, I
spent time in these areas of thecountry, but I've seen henbit,
not deadnettle here and only ingarden beds around campus,
typically not a weed that wefind in fields here. Our our
winter annual choice that, well,we've got several, but field
pennycress is one that kind ofdominates our landscape a lot of
(07:15):
the time.
Bill Johnson (07:16):
Yeah, and if I remember back from my days in
Missouri, it seems like we hadmore henbit in Missouri than we
did deadnettle. And then when Igot east of the Wabash River,
seems like we have a little bitmore purple deadnettle than than
henbit.
Joe Ikley (07:33):
So circling back to control conventional tillage,
hopefully your spring tillageoperation will take these things
out. But what about differentherbicide programs, herbicide
timings? Any commonalities ordifferences between corn and
soybean?
Bill Johnson (07:49):
Well, I think the common ingredients would be
roundup in two, 4d obviously,they're going to be low cost and
very efficacious on a number ofdifferent weeds. I think you
know, we started to use a lotmore Dicamba recently, as well
as the prices have come down,and we've had the availability
to to use the trait in soybeans,so we haven't needed a long pre
(08:11):
plant interval. So I think ifyou start off with those basics,
if you're looking for residualcontrol in soybeans, a lot of
the classic, the herbicides thatcontain classic or metribuzin in
them give you good residualactivity. Other herbicides that
contain pursuit, scepter,firstrate and things like that
(08:32):
seem to work fairly well on onthese as well. When you're in a
soybean system in corn, again,it's it's roundup, 2,4-D,
sometimes there's some simazinethat's used in the fall that
does a good job of suppressingit and kind of persisting until
the spring to get some of thespring germinating cohorts as
well. And then many of theAtrazine pre mixes that you'll
(08:54):
use in the spring will have somesome decent activity on on a lot
of winter annual broadleafweeds.
Joe Ikley (09:01):
So plenty of options and those two staple crops, what
about do you have any questionsabout them in winter wheat, so
controlling it actively withinthat crop?
Bill Johnson (09:11):
Yeah, yes, we do. Typically, where the wheat
stands are thin and Sarah isgoing to be our wheat or
actually both you guys are goingto be our wheat herbicide
experts. You guys have morewheat in your two states, and
I've probably seen in my entirelife. But you know, in the
eastern Corn Belt, typically,the harmony type products work
(09:32):
fairly well on a broad spectrumof winter annual weeds, and they
work on hebit and deadnettle aswell.
Joe Ikley (09:40):
I'm spring wheat, whole different portfolio. So
Sarah has fill in the gaps herefor this particular situation.
Sarah Lancaster (09:46):
Yeah, harmony. And one of the things that I see
going out a lot, just, you know,talking with farmers here is
like a top dress with MCPA,right? So you put your nitrogen
fertilizer and going with someMCPA, you try. To avoid 2,4-D
and wheat for crop crop safetyconcerns, but that'd be another
one that's pretty cost effectiveand pretty easy for folks to do.
Joe Ikley (10:11):
So begs the question, I guess for both of you, maybe
then pretty popular herbicidechoice within the system. There
ever get phone calls of it justnot quite working. I don't think
we've documented any resistancein these weeds. But
Bill Johnson (10:26):
I think with the Spring application, sometimes
Yeah I was just thinking withinwheat, I don't think I've even
the speed of activity isn't whatpeople would like to see. And I
think that's that's reallyrelated to the cold weather
conditions. You know, sometimesin the fall, if we do these fall
applications, really late in thefall, like second half of
November. It seems like the theweeds would just kind of sit
(10:46):
there forever and not doanything. And then when you come
back in the spring, they'regone. They they've died over the
winter time. So I do think, youknow, you think about roundup
and 2,4-D as your baseherbicides, or systemic
herbicides. They just don't workfast when it when the weather
conditions are cool.
heard of group two resistance,and those two mint plants
(11:07):
versus, I know a commonchickweed can be more common,
and that does have some grouptwo resistance within our our
wheat crop
Sarah Lancaster (11:16):
well. And I was thinking, Dallas had I was
thinking they had a populationof hidden bit. I was trying to
look it up.
Joe Ikley (11:26):
Are you sure he wasn't just growing it because
it's the same color, purple asyour, uh, your logo down there.
Sarah Lancaster (11:33):
Theyre not royal purple, more lavender,
right?
Bill Johnson (11:40):
I think that means stay off my land if you're a
hunter. I see all the fenceposts painted that color.
Sarah Lancaster (11:52):
Well, it's about this time every spring we
get the Facebook posts andTwitter posts about henbit
should be a cover crop, and sowe can talk a little bit more
about why that's not the caselater. The other the most
interesting thing I've seen in afield of henbit, though, is
somebody taking, like, formalpictures. It was a teenage girl
(12:15):
in a formal dress in this fieldof hin bit, oh, sister. Okay, so
yes, 2014 henbit, group two fromKansas.
Bill Johnson (12:26):
Okay, which? Which group two was it?
Sarah Lancaster (12:29):
They tested it for Glean.
Bill Johnson (12:33):
Okay. which, That was probably western Kansas,
right? That's where a lot ofglean would have been used?
Joe Ikley (12:38):
wheat on wheat acres there.
Sarah Lancaster (12:40):
Central Kansas, yeah, okay, I had to guess I
would say kind of that I 135 US,81 corridor.
Joe Ikley (12:50):
You know Sarah you're not helping the case at all.
Resistance starts with you andDallas,
Sarah Lancaster (12:55):
Blame Dallas, not me. This is Dallas. This is
not me. Passenger here.
Joe Ikley (13:03):
All right. So, yes, there is some group two
resistance, but not verywidespread. So kind of
transitioning then. So plenty ofyou know, plenty of control
programs within the major cropswhere these, these two weeds,
tend to thrive and relativelyeasy and cheap to clean up. So
what's the negative impact ofthese weeds? Are they just out
there being purple flowers andmaking it look pretty? Or why
(13:25):
should we really care aboutthem?
Bill Johnson (13:28):
There's really sort of two things that these
things will do in terms ofimpacting crop production. So
the first is that in these notill fields, I think,
particularly where they have alot of clay content, they will
keep the the soils wet in thespring. They they slow the
wetting and drying, because theydon't transpire. They're not
big, aggressive, high biomassplants, like a cereal rye or
(13:52):
something like that is so theydon't transpire a lot of water.
So I think that's that's onenegative to them. The other
thing is that they can serve asan alternative host for soybean
cyst nematode. So I'll give someprops to my my former colleague
at Ohio State, Kent Harrison,started playing around a little
(14:12):
bit with this in the late 90s,early 2000s and then when I came
over to Purdue, Kent and I weretalking and and we decided to
put together some collaborativeresearch projects when when he
was over there. So we had a wewere able to fund a couple of
graduate students to work onthat topic. And basically what
we learned through thoseprojects is that hand bit and
(14:33):
purple deadnettle can support asmuch reproduction of SCN as a
susceptible soybean variety. Sothey're considered a strong host
for for SCN number one and thennumber two. We also showed that,
you know, particularly if youthink about the geography from
(14:53):
Indianapolis and on south sothat that kind of geography, we
can get another round ofreproductive. Production on
hand, bit or purple deadnettlein the fall. So if you think
about you know, soil temps haveto be 50 degrees or higher, and
typically it takes around 30days or so to get a generation
of reproduction. And we can havethe weather conditions in that
(15:18):
area that allows another roundof reproduction in the fall, so
the populations can increase onthose weeds, even when you don't
have a susceptible crop in thefield.
Joe Ikley (15:28):
Just trying to think we're not, we're not 50 degrees
in the fall, but I've seen ourwinter annuals hang on into July
around here. So that's notsomething we want, because I
don't listen too closely to ourpathologists, but they talk
about nematodes an awful lot.
Bill Johnson (15:42):
Yeah, it is re emerged as one of the scourges
of the Midwest with, you know,due to some of the resistance
that's happening on the geneticmaterial to the genetic
material.
Sarah Lancaster (15:54):
Well, look, and it seems to me like as our
soybean acres move west, there'sa whole nother kind of group of
farmers that kind of need thisinformation because they're not
as familiar with soybeans as,say, Missouri bill. So we talked
a little bit about herbicides,but I wondered, should we kind
of hone in on that timing ofapplication, kind of all versus
(16:17):
spring? I don't think we reallytouched on that for like, a head
of corn or so? Yeah,
Joe Ikley (16:23):
I think it's worth going into that. And I know Bill
would set up that there is somespring emergence. But you know,
the time you've been in Missouriand Indiana, what's, what's been
the best timing for these bill,well,
Bill Johnson (16:35):
in terms of just, just killing the weeds,
obviously, when you have, well,they're easier to kill in the
fall because they're they'reactively growing for a long
period of time. They're not inthat, you know that winter
slumber or hibernation, and sothey're just easier to kill in
the fall. I think, when youthink about timing, though, you
(16:57):
know when I when I recommendsystemic herbicides like Roundup
2,4-D, whatever it happens tobe, what I like to see is
daytime air temps in the 50s andnighttime air temps that haven't
got down into the 30s. So ifwe're kind of 40 and above
nighttime, 50 and above daytime,and we have a couple of days in
a row of that, that seems to bea pretty good situation from a
(17:18):
herbicide activity standpoint.But I think if we think about
timing the herbicide applicationto minimize SCN reproduction, we
literally need to follow thecombines with the sprayer.
Because, you know, we if wethink about in October harvest
timing, if we have kind of a wetSeptember, we can get these
(17:41):
weeds emerging underneath thecrop canopy in September, and it
could be by the time we harvestin October, you've had enough
time pass and enough heat unitsaccumulated that you can get
another round of reproduction ofSCN by the time the combines
rolled through the field andyou're able to spray in October.
So I think the fallapplications, from the
(18:03):
standpoint of SCN management,need to go out as early as
possible, and it does benefit tohave some residual activity with
that for these early Octoberapplications, to try to keep
additional ones from coming uplater in the fall.
Joe Ikley (18:17):
It sounds like based on just moisture management, you
want to target the fall for thatpurpose of the spring as well.
Yes, yep. So I was, I was tryingto think back, remember, and you
know, you'll be a lot morefamiliar with the exact work.
But you know, what are some ofthe other just things you found
along the way with some thisalternative host of soybean cyst
nematode, there's a bunch ofgreenhouse work involved as well
(18:39):
as the field work,
Bill Johnson (18:40):
yeah. And I was just reviewing that publication
prior to to this meeting. Soessentially, we we identified
six hosts that were fairlycommon in the eastern Corn Belt.
So henbit and purple deadnettlewere what were fairly common,
but common chick weed isconsidered a weak host, small
(19:02):
flower, bitter crest shepherds,purse and field Penny crests are
also considered to be weak hostsas well. Common chick weed is is
typically found in the highestpercentage of the of the no till
fields in the eastern Corn Belt.But it's not quite as strong of
a host as henbit and purpledeadnettle are. So those are the
six winter annual weed hoststhat we have found. We've done
(19:27):
some work too with, you know,with some of the cover crops
that can be suppressive on onSCN, and haven't had a lot of
great luck with that. There's,there's some varieties of annual
rye that are supposed to besuppressive to SCN. So we've
done some field and somegreenhouse work, and it hasn't
(19:47):
really shown much of an impacton SCN population densities. So
I think that's there's stillmore work to be done with that
as a management tactic. So rightnow, what I would say, if you're
if you're managing. Um weeds tomanage SCN herbicide
applications as early in thefall as you can possibly apply
them, is is going to be thepreferred strategy.
Joe Ikley (20:08):
So what I'm hearing we have these weeds and a lot of
acres, causes a lot of questionsin the spring, still some good
control programs and some goodreasons to control them.
Bill Johnson (20:23):
Yeah, I think that kind of that kind of sums it up.
Joe Ikley (20:28):
Never would have thought that in just about 20
minutes could answer all thesequestions and stave off hundreds
of phone calls each spring. Didyou bill?
Bill Johnson (20:38):
I hope that's the case.
Joe Ikley (20:47):
Sarah, do you have any other lingering questions?
We kind of got through the listI said, I don't think I said
this at the odd set won't so Ihit record, but figured we might
be pretty efficient with thisone.
Sarah Lancaster (20:58):
Yeah, there was something that had. Oh, did you
look at any weeds that were nothosts? You rattled off the six
that were.
Bill Johnson (21:10):
yeah so Valerie did that work. Valerie and Earl
did that work in my lab, andKent had a student. I don't
remember that student's name.Kent actually screened. So Kent
actually has a paper and weedtechnology. Kent screened a
bunch of weeds, winter annualsand summer annuals. And I don't
(21:34):
remember exactly what thatshowed. So we never did that
work. Since Kent did that work,Joe, there might be somebody at
South Dakota State that's doingsome work on this.
Joe Ikley (21:47):
I think Sharon Clay had done some, some of that
work. So I'd have to, she wouldhave published in Weed Science,
but I have to go back and lookwhat she did. But I seem to
remember her identifying fieldPenny crests. So maybe, I don't
know there's a, I can't remembershe classified as weak host or
strong host. Or maybe there'ssome bio type differences
(22:08):
between the SCN and the Dakotas,or the field Penny crestes of
the east versus East, Corn Beltversus northern plains. But I
seem to remember that one risingto the top of her list. Or maybe
it's just because fieldpennycress is everywhere up
here.
Bill Johnson (22:24):
Yeah. Well, yeah. And I was, I was going to say,
from what I remember, thereweren't any summer annual weeds
that were nearly as strong of ahost as these winter annuals
are. You can get somereproduction on some of the
summer annuals, but it's notnearly the amount that you can
get on some of these winterannuals. For some reason,
Joe Ikley (22:42):
does make me wonder. There's one summer annual we
have, and it's it's kind of funwhen it shows up in a plot,
because we, we tend to kill itwith a lot of our corn soybean
herbicides. But Lance leaf sageis another mint that we deal
with and Sarah, you probably seeit on occasion further south,
but we can get the occasionalfield where it's just thick
Lance leaf sage. And if you'rein a any sort of Roundup Ready
(23:06):
soybean, we've got plenty ofoptions. Are in corn, but a lot
of our specialty crops, we don'talways have the best control of
Lance leaf sage. Of I'd becurious about that one where we
get patches it's thick and it'sa mint, but it's not the
widespread just endless fieldsof purple flowers, like some of
these winter annuals can be,yeah?
Bill Johnson (23:25):
I think the thing to do is just, you know, pull up
some plants and knock the soiloff and see if you see any cysts
on the roots. That's they'repretty easy to diagnose that
way,
Sarah Lancaster (23:35):
yeah, because all of those winter annuals you
listed, you know, a lot of themare mustards. And so I'm
thinking about our mustardpopulations that we sometimes
get in our wheat fields and thenand areas, particularly in the
southern part of the state, willgo ahead and double crop
soybeans into that so I'm justwondering what kind of extra
problems our guys are setting upfor themselves in that scenario.
Bill Johnson (23:55):
Yeah, well, and then pennycress and pennycress
would fall into that mustardfamily.
Joe Ikley (24:00):
Wondering if I've seen anything, they've tested
canola. I'm sure they would havehad to have but that's the
interesting one I hear mostabout from our pathologist.
Besides soybean is some dry beanvarieties tend to be very
susceptible to SCN too but Ihaven't heard them mention any
of the other crops that we'retypically dealing with well. So
(24:21):
we should probably go ahead andwrap this one up then. So Bill
any, any parting thoughts of onhenbit or purple deadnettle?
Bill Johnson (24:29):
Well, I think again, if these weeds are, you
know, causing problems in yourfield, and you also have some
kind of unexplained yield loss,I would have your field tested
for or sampled for SCN as well.And always keep in mind that in
terms of SCN management,planting genetic material that
has resistance to SCN is alwaysa great strategy, and herbicide
(24:55):
applications can kind of helpnibble at the edges, but it
really shouldn't. Be the bighammer that you use for SCN
management.
Joe Ikley (25:04):
All right, now we're getting dangerously close to a
pathology podcast. We reallyneed to wrap this up now. So,
but before we go, Bill, do youwant to the folks know where
they can find you if you'restill active on any social
media, or
Bill Johnson (25:19):
if I could remember those uh, Twitter
sites, I probably would.
Joe Ikley (25:26):
We'll find you, see if you're active, and tag you in
the show notes. But with that,we'd like to thank you, Bill for
coming back on and then talkingabout these couple of weeds with
us. Thanks, as always, to thelisteners, and we'll catch you
next time on the war againstweeds.
(25:51):
As always, we thank you forlistening to the war against
weeds podcast. Just anotherreminder, you can find our
podcast hosted on the CropProtection Network, or CPN, for
short. So this is another greatresource that's driven, by
extension, scientists atdifferent universities for pest
management. And with that, wewill see you next week on the
war against weeds podcast. You.
Welcome back to the war against weeds Podcast. I'm
Joe Ikley, extension weedspecialist at North Dakota State
University. My co host today isDr Sarah Lancaster, down at K
State Sarah, how are you today?
Sarah Lancaster (00:20):
Doing great. mourning the Chiefs lost. We're
recording this the day after theSuper Bowl, so the entire state
is in morning till you get tothe Denver Broncos fans,
Joe Ikley (00:31):
I'm an eight hour drive from any any playoff team,
so found better things to do,but we're not talking football,
although we'll see if anyreferences weave their way in
throughout the course of this.But our guest today is Dr Bill
Johnson at Purdue University,repeat guest. So Bill, welcome
back.
Bill Johnson (00:51):
Thank you for having me. Glad to be back. Good
to see you guys again.
Joe Ikley (00:56):
And in case people haven't listened or don't know
who you are, we should go aheadand have you reintroduce
yourself and all the greatthings you do at Purdue.
Bill Johnson (01:03):
Oh yeah, yeah. Well, yeah, thanks for having me
again. So again, my name is BillJohnson. I'm an Extension weed
scientist. I've been at Purduefor about 23 years, and prior to
that, I was at the University ofMissouri. So I've always had an
extension appointment during myfaculty career. So I've been
able to see a lot of trendschange over the course of time.
(01:24):
And one of the interests I'vealways had in my research
program are interactions betweenweeds and other plant pests.
Those are the things I enjoytalking about as well.
Joe Ikley (01:32):
Well, that's a good segue into why we had you on.
And so I figured I would startwith a question I know you get
about at least March, if notthis time of year every year. So
in eastern the eastern Corn BeltBill, what are all those purple
flowers in the field?
Bill Johnson (01:50):
Yeah, well, good question. So one of the things
that makes many of our no tillfields so colorful in the spring
of the year are weeds that havedifferent colored flowers. So
the purple flowered weeds areactually from the mint family,
and henbit and purple deadnettleare the two most common ones
that we see that that have thesepurple flowers in our no till
(02:12):
fields.
Joe Ikley (02:13):
And so what makes those two mint species common?
Bill Johnson (02:18):
Well, they're winter annual weeds. They
survive in a system where theycan emerge before the crop is
harvested in the fall. So asthese fields retain a little bit
of moisture in the fall from theleaves falling off the crop
plants, these weeds willgerminate very shallow in the
soil. They're able to survivethe harvesting operation because
(02:43):
they're low growing weeds. Theygrow below the cutter height, or
the or the head height for acorn machine. And then they have
the ability to establish on manydifferent soil types. They tend
to like wet soil types inparticular. And then they will
survive the the winter months,and then they resume their life
(03:03):
cycle in the spring, where thepurple flowers typically come
out when, when wheat starts togreen up. And then they'll,
they'll go on and produce seedshortly after that. And then
once the weather temperaturesare typically in the 80s for on
a regular basis, and they, theycan, they senesce and die and
(03:23):
drop their seeds. And theprocess starts all over in the
fall.
Joe Ikley (03:27):
I know you mentioned no till, but have a conventional
tillage. Are they? Are theyoften found in those I mean, I
know there's an easy way toterminate them in that system,
but are you seeing a lot of thehenbit and deadnettle in these
conventional tilled fields aswell.
Bill Johnson (03:42):
Well? Good question. So, yes, we can see
them in conventional till fieldsas well. I think particularly if
you have a situation where we'veharvested the crop early and we
have an extended fall, and wehave good moisture in the fall,
these weeds can, can come up ina situation like that. And you
(04:03):
know, I think if you think aboutour the changes that we have
going on in our climate,regardless of what the causes
are, the Falls tend to be longerthan they were many years ago.
So I think, you know, as we getthat early, early harvest taken
off the field, these weeds havea chance to germinate and
establish in the fall. And Iwill also note that many winter
(04:25):
annual weeds also have theability to germinate and grow in
the spring as well. So I thinkparticularly as we get to the
center and southern part of thecorn and soybean growing areas,
spring starts really early. Andso when we start having these 50
and 60 degree days in February,we can get some spring emergence
(04:46):
of these, these weeds as well.And that can happen, whether
it's in no till or inconventional till.
Joe Ikley (04:52):
Sarah, the focus so far has been the eastern Corn
Belt. But do you deal with themint families there in Kansas?
Sarah Lancaster (05:00):
Not in the western part of the state, sort
of as you drive west alongInterstate 70 in Kansas, you
trade fields of purple forkochia in the fence lines.
That's sort of how you know whenyou're in western Kansas. I
wondered, though, Bill, do youthink it would be maybe
interesting for some of thelisteners to just talk about
(05:21):
some of the differences betweenhenbit and purple deadnettle.
Bill Johnson (05:26):
Yeah, yeah. I think the there, it's very easy
to to confuse them from adistance, they have kind of a
rough leaf texture. When viewedfrom the top, they also have the
purple flowers as well. But ifyou, if you pull the plants up
and hold them side by side, andthere's a lot of good images you
can Google them, and there's alot of good images you can pull
up on the web. Purple deadnettlewill have more of a triangular
(05:50):
shaped leaf, and the leaf willactually have a short petiole
between the leaflet and thestem. And henbit tends to
produce these sort of half moonshaped leaves that tend to stick
almost directly onto the stem.Now both plants will have a
square stem, and that's how wedifferentiate plants that are in
the mint family, but again, veryeasy to confuse them. And if you
(06:14):
pull them up and look at themclosely, then it's pretty easy
to tell them apart. One thingthat we see a lot of as well as
it's rare. It seems like it'sit's somewhat rare to have hand
bit and purple deadnettle in thesame field. We tend to have one
or the other, and it's kind ofrare to have both of them. And I
don't know the biologicalreasoning for that. That's just
(06:34):
been an observation through someof our survey work.
Joe Ikley (06:37):
So besides nerds like us, who like to identify stuff
and get asked these questions,does it matter for management,
which one of the two you have
Bill Johnson (06:46):
no in the in the work that we've done on no till
weeds, that it doesn't matterthe herbicide program for
controlling both is going to bethe same.
Joe Ikley (06:54):
And so I'm also partly asking so, I mean, I
spent time in these areas of thecountry, but I've seen henbit,
not deadnettle here and only ingarden beds around campus,
typically not a weed that wefind in fields here. Our our
winter annual choice that, well,we've got several, but field
pennycress is one that kind ofdominates our landscape a lot of
(07:15):
the time.
Bill Johnson (07:16):
Yeah, and if I remember back from my days in
Missouri, it seems like we hadmore henbit in Missouri than we
did deadnettle. And then when Igot east of the Wabash River,
seems like we have a little bitmore purple deadnettle than than
henbit.
Joe Ikley (07:33):
So circling back to control conventional tillage,
hopefully your spring tillageoperation will take these things
out. But what about differentherbicide programs, herbicide
timings? Any commonalities ordifferences between corn and
soybean?
Bill Johnson (07:49):
Well, I think the common ingredients would be
roundup in two, 4d obviously,they're going to be low cost and
very efficacious on a number ofdifferent weeds. I think you
know, we started to use a lotmore Dicamba recently, as well
as the prices have come down,and we've had the availability
to to use the trait in soybeans,so we haven't needed a long pre
(08:11):
plant interval. So I think ifyou start off with those basics,
if you're looking for residualcontrol in soybeans, a lot of
the classic, the herbicides thatcontain classic or metribuzin in
them give you good residualactivity. Other herbicides that
contain pursuit, scepter,firstrate and things like that
(08:32):
seem to work fairly well on onthese as well. When you're in a
soybean system in corn, again,it's it's roundup, 2,4-D,
sometimes there's some simazinethat's used in the fall that
does a good job of suppressingit and kind of persisting until
the spring to get some of thespring germinating cohorts as
well. And then many of theAtrazine pre mixes that you'll
(08:54):
use in the spring will have somesome decent activity on on a lot
of winter annual broadleafweeds.
Joe Ikley (09:01):
So plenty of options and those two staple crops, what
about do you have any questionsabout them in winter wheat, so
controlling it actively withinthat crop?
Bill Johnson (09:11):
Yeah, yes, we do. Typically, where the wheat
stands are thin and Sarah isgoing to be our wheat or
actually both you guys are goingto be our wheat herbicide
experts. You guys have morewheat in your two states, and
I've probably seen in my entirelife. But you know, in the
eastern Corn Belt, typically,the harmony type products work
(09:32):
fairly well on a broad spectrumof winter annual weeds, and they
work on hebit and deadnettle aswell.
Joe Ikley (09:40):
I'm spring wheat, whole different portfolio. So
Sarah has fill in the gaps herefor this particular situation.
Sarah Lancaster (09:46):
Yeah, harmony. And one of the things that I see
going out a lot, just, you know,talking with farmers here is
like a top dress with MCPA,right? So you put your nitrogen
fertilizer and going with someMCPA, you try. To avoid 2,4-D
and wheat for crop crop safetyconcerns, but that'd be another
one that's pretty cost effectiveand pretty easy for folks to do.
Joe Ikley (10:11):
So begs the question, I guess for both of you, maybe
then pretty popular herbicidechoice within the system. There
ever get phone calls of it justnot quite working. I don't think
we've documented any resistancein these weeds. But
Bill Johnson (10:26):
I think with the Spring application, sometimes
Yeah I was just thinking withinwheat, I don't think I've even
the speed of activity isn't whatpeople would like to see. And I
think that's that's reallyrelated to the cold weather
conditions. You know, sometimesin the fall, if we do these fall
applications, really late in thefall, like second half of
November. It seems like the theweeds would just kind of sit
(10:46):
there forever and not doanything. And then when you come
back in the spring, they'regone. They they've died over the
winter time. So I do think, youknow, you think about roundup
and 2,4-D as your baseherbicides, or systemic
herbicides. They just don't workfast when it when the weather
conditions are cool.
heard of group two resistance,and those two mint plants
(11:07):
versus, I know a commonchickweed can be more common,
and that does have some grouptwo resistance within our our
wheat crop
Sarah Lancaster (11:16):
well. And I was thinking, Dallas had I was
thinking they had a populationof hidden bit. I was trying to
look it up.
Joe Ikley (11:26):
Are you sure he wasn't just growing it because
it's the same color, purple asyour, uh, your logo down there.
Sarah Lancaster (11:33):
Theyre not royal purple, more lavender,
right?
Bill Johnson (11:40):
I think that means stay off my land if you're a
hunter. I see all the fenceposts painted that color.
Sarah Lancaster (11:52):
Well, it's about this time every spring we
get the Facebook posts andTwitter posts about henbit
should be a cover crop, and sowe can talk a little bit more
about why that's not the caselater. The other the most
interesting thing I've seen in afield of henbit, though, is
somebody taking, like, formalpictures. It was a teenage girl
(12:15):
in a formal dress in this fieldof hin bit, oh, sister. Okay, so
yes, 2014 henbit, group two fromKansas.
Bill Johnson (12:26):
Okay, which? Which group two was it?
Sarah Lancaster (12:29):
They tested it for Glean.
Bill Johnson (12:33):
Okay. which, That was probably western Kansas,
right? That's where a lot ofglean would have been used?
Joe Ikley (12:38):
wheat on wheat acres there.
Sarah Lancaster (12:40):
Central Kansas, yeah, okay, I had to guess I
would say kind of that I 135 US,81 corridor.
Joe Ikley (12:50):
You know Sarah you're not helping the case at all.
Resistance starts with you andDallas,
Sarah Lancaster (12:55):
Blame Dallas, not me. This is Dallas. This is
not me. Passenger here.
Joe Ikley (13:03):
All right. So, yes, there is some group two
resistance, but not verywidespread. So kind of
transitioning then. So plenty ofyou know, plenty of control
programs within the major cropswhere these, these two weeds,
tend to thrive and relativelyeasy and cheap to clean up. So
what's the negative impact ofthese weeds? Are they just out
there being purple flowers andmaking it look pretty? Or why
(13:25):
should we really care aboutthem?
Bill Johnson (13:28):
There's really sort of two things that these
things will do in terms ofimpacting crop production. So
the first is that in these notill fields, I think,
particularly where they have alot of clay content, they will
keep the the soils wet in thespring. They they slow the
wetting and drying, because theydon't transpire. They're not
big, aggressive, high biomassplants, like a cereal rye or
(13:52):
something like that is so theydon't transpire a lot of water.
So I think that's that's onenegative to them. The other
thing is that they can serve asan alternative host for soybean
cyst nematode. So I'll give someprops to my my former colleague
at Ohio State, Kent Harrison,started playing around a little
(14:12):
bit with this in the late 90s,early 2000s and then when I came
over to Purdue, Kent and I weretalking and and we decided to
put together some collaborativeresearch projects when when he
was over there. So we had a wewere able to fund a couple of
graduate students to work onthat topic. And basically what
we learned through thoseprojects is that hand bit and
(14:33):
purple deadnettle can support asmuch reproduction of SCN as a
susceptible soybean variety. Sothey're considered a strong host
for for SCN number one and thennumber two. We also showed that,
you know, particularly if youthink about the geography from
(14:53):
Indianapolis and on south sothat that kind of geography, we
can get another round ofreproductive. Production on
hand, bit or purple deadnettlein the fall. So if you think
about you know, soil temps haveto be 50 degrees or higher, and
typically it takes around 30days or so to get a generation
of reproduction. And we can havethe weather conditions in that
(15:18):
area that allows another roundof reproduction in the fall, so
the populations can increase onthose weeds, even when you don't
have a susceptible crop in thefield.
Joe Ikley (15:28):
Just trying to think we're not, we're not 50 degrees
in the fall, but I've seen ourwinter annuals hang on into July
around here. So that's notsomething we want, because I
don't listen too closely to ourpathologists, but they talk
about nematodes an awful lot.
Bill Johnson (15:42):
Yeah, it is re emerged as one of the scourges
of the Midwest with, you know,due to some of the resistance
that's happening on the geneticmaterial to the genetic
material.
Sarah Lancaster (15:54):
Well, look, and it seems to me like as our
soybean acres move west, there'sa whole nother kind of group of
farmers that kind of need thisinformation because they're not
as familiar with soybeans as,say, Missouri bill. So we talked
a little bit about herbicides,but I wondered, should we kind
of hone in on that timing ofapplication, kind of all versus
(16:17):
spring? I don't think we reallytouched on that for like, a head
of corn or so? Yeah,
Joe Ikley (16:23):
I think it's worth going into that. And I know Bill
would set up that there is somespring emergence. But you know,
the time you've been in Missouriand Indiana, what's, what's been
the best timing for these bill,well,
Bill Johnson (16:35):
in terms of just, just killing the weeds,
obviously, when you have, well,they're easier to kill in the
fall because they're they'reactively growing for a long
period of time. They're not inthat, you know that winter
slumber or hibernation, and sothey're just easier to kill in
the fall. I think, when youthink about timing, though, you
(16:57):
know when I when I recommendsystemic herbicides like Roundup
2,4-D, whatever it happens tobe, what I like to see is
daytime air temps in the 50s andnighttime air temps that haven't
got down into the 30s. So ifwe're kind of 40 and above
nighttime, 50 and above daytime,and we have a couple of days in
a row of that, that seems to bea pretty good situation from a
(17:18):
herbicide activity standpoint.But I think if we think about
timing the herbicide applicationto minimize SCN reproduction, we
literally need to follow thecombines with the sprayer.
Because, you know, we if wethink about in October harvest
timing, if we have kind of a wetSeptember, we can get these
(17:41):
weeds emerging underneath thecrop canopy in September, and it
could be by the time we harvestin October, you've had enough
time pass and enough heat unitsaccumulated that you can get
another round of reproduction ofSCN by the time the combines
rolled through the field andyou're able to spray in October.
So I think the fallapplications, from the
(18:03):
standpoint of SCN management,need to go out as early as
possible, and it does benefit tohave some residual activity with
that for these early Octoberapplications, to try to keep
additional ones from coming uplater in the fall.
Joe Ikley (18:17):
It sounds like based on just moisture management, you
want to target the fall for thatpurpose of the spring as well.
Yes, yep. So I was, I was tryingto think back, remember, and you
know, you'll be a lot morefamiliar with the exact work.
But you know, what are some ofthe other just things you found
along the way with some thisalternative host of soybean cyst
nematode, there's a bunch ofgreenhouse work involved as well
(18:39):
as the field work,
Bill Johnson (18:40):
yeah. And I was just reviewing that publication
prior to to this meeting. Soessentially, we we identified
six hosts that were fairlycommon in the eastern Corn Belt.
So henbit and purple deadnettlewere what were fairly common,
but common chick weed isconsidered a weak host, small
(19:02):
flower, bitter crest shepherds,purse and field Penny crests are
also considered to be weak hostsas well. Common chick weed is is
typically found in the highestpercentage of the of the no till
fields in the eastern Corn Belt.But it's not quite as strong of
a host as henbit and purpledeadnettle are. So those are the
six winter annual weed hoststhat we have found. We've done
(19:27):
some work too with, you know,with some of the cover crops
that can be suppressive on onSCN, and haven't had a lot of
great luck with that. There's,there's some varieties of annual
rye that are supposed to besuppressive to SCN. So we've
done some field and somegreenhouse work, and it hasn't
(19:47):
really shown much of an impacton SCN population densities. So
I think that's there's stillmore work to be done with that
as a management tactic. So rightnow, what I would say, if you're
if you're managing. Um weeds tomanage SCN herbicide
applications as early in thefall as you can possibly apply
them, is is going to be thepreferred strategy.
Joe Ikley (20:08):
So what I'm hearing we have these weeds and a lot of
acres, causes a lot of questionsin the spring, still some good
control programs and some goodreasons to control them.
Bill Johnson (20:23):
Yeah, I think that kind of that kind of sums it up.
Joe Ikley (20:28):
Never would have thought that in just about 20
minutes could answer all thesequestions and stave off hundreds
of phone calls each spring. Didyou bill?
Bill Johnson (20:38):
I hope that's the case.
Joe Ikley (20:47):
Sarah, do you have any other lingering questions?
We kind of got through the listI said, I don't think I said
this at the odd set won't so Ihit record, but figured we might
be pretty efficient with thisone.
Sarah Lancaster (20:58):
Yeah, there was something that had. Oh, did you
look at any weeds that were nothosts? You rattled off the six
that were.
Bill Johnson (21:10):
yeah so Valerie did that work. Valerie and Earl
did that work in my lab, andKent had a student. I don't
remember that student's name.Kent actually screened. So Kent
actually has a paper and weedtechnology. Kent screened a
bunch of weeds, winter annualsand summer annuals. And I don't
(21:34):
remember exactly what thatshowed. So we never did that
work. Since Kent did that work,Joe, there might be somebody at
South Dakota State that's doingsome work on this.
Joe Ikley (21:47):
I think Sharon Clay had done some, some of that
work. So I'd have to, she wouldhave published in Weed Science,
but I have to go back and lookwhat she did. But I seem to
remember her identifying fieldPenny crests. So maybe, I don't
know there's a, I can't remembershe classified as weak host or
strong host. Or maybe there'ssome bio type differences
(22:08):
between the SCN and the Dakotas,or the field Penny crestes of
the east versus East, Corn Beltversus northern plains. But I
seem to remember that one risingto the top of her list. Or maybe
it's just because fieldpennycress is everywhere up
here.
Bill Johnson (22:24):
Yeah. Well, yeah. And I was, I was going to say,
from what I remember, thereweren't any summer annual weeds
that were nearly as strong of ahost as these winter annuals
are. You can get somereproduction on some of the
summer annuals, but it's notnearly the amount that you can
get on some of these winterannuals. For some reason,
Joe Ikley (22:42):
does make me wonder. There's one summer annual we
have, and it's it's kind of funwhen it shows up in a plot,
because we, we tend to kill itwith a lot of our corn soybean
herbicides. But Lance leaf sageis another mint that we deal
with and Sarah, you probably seeit on occasion further south,
but we can get the occasionalfield where it's just thick
Lance leaf sage. And if you'rein a any sort of Roundup Ready
(23:06):
soybean, we've got plenty ofoptions. Are in corn, but a lot
of our specialty crops, we don'talways have the best control of
Lance leaf sage. Of I'd becurious about that one where we
get patches it's thick and it'sa mint, but it's not the
widespread just endless fieldsof purple flowers, like some of
these winter annuals can be,yeah?
Bill Johnson (23:25):
I think the thing to do is just, you know, pull up
some plants and knock the soiloff and see if you see any cysts
on the roots. That's they'repretty easy to diagnose that
way,
Sarah Lancaster (23:35):
yeah, because all of those winter annuals you
listed, you know, a lot of themare mustards. And so I'm
thinking about our mustardpopulations that we sometimes
get in our wheat fields and thenand areas, particularly in the
southern part of the state, willgo ahead and double crop
soybeans into that so I'm justwondering what kind of extra
problems our guys are setting upfor themselves in that scenario.
Bill Johnson (23:55):
Yeah, well, and then pennycress and pennycress
would fall into that mustardfamily.
Joe Ikley (24:00):
Wondering if I've seen anything, they've tested
canola. I'm sure they would havehad to have but that's the
interesting one I hear mostabout from our pathologist.
Besides soybean is some dry beanvarieties tend to be very
susceptible to SCN too but Ihaven't heard them mention any
of the other crops that we'retypically dealing with well. So
(24:21):
we should probably go ahead andwrap this one up then. So Bill
any, any parting thoughts of onhenbit or purple deadnettle?
Bill Johnson (24:29):
Well, I think again, if these weeds are, you
know, causing problems in yourfield, and you also have some
kind of unexplained yield loss,I would have your field tested
for or sampled for SCN as well.And always keep in mind that in
terms of SCN management,planting genetic material that
has resistance to SCN is alwaysa great strategy, and herbicide
(24:55):
applications can kind of helpnibble at the edges, but it
really shouldn't. Be the bighammer that you use for SCN
management.
Joe Ikley (25:04):
All right, now we're getting dangerously close to a
pathology podcast. We reallyneed to wrap this up now. So,
but before we go, Bill, do youwant to the folks know where
they can find you if you'restill active on any social
media, or
Bill Johnson (25:19):
if I could remember those uh, Twitter
sites, I probably would.
Joe Ikley (25:26):
We'll find you, see if you're active, and tag you in
the show notes. But with that,we'd like to thank you, Bill for
coming back on and then talkingabout these couple of weeds with
us. Thanks, as always, to thelisteners, and we'll catch you
next time on the war againstweeds.
(25:51):
As always, we thank you forlistening to the war against
weeds podcast. Just anotherreminder, you can find our
podcast hosted on the CropProtection Network, or CPN, for
short. So this is another greatresource that's driven, by
extension, scientists atdifferent universities for pest
management. And with that, wewill see you next week on the
war against weeds podcast. You.
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