April 7, 2025 • 30 mins
Together, the UCCE Farm Advisors seek to provide relevant, topical research-backed information relating to CA rice production.
Sarah Marsh Janish sits down with Dr. Kassim Al-Khatib, who is responsible for the Herbicide Resistance Screening Program that UC Cooperative Extension provides, free of charge, to rice growers and PCAs who are interested in determining the herbicide resistance status of their rice weeds.
Herbicide Resistance Testing Form
Resistant Weed Seed Testing Resources
Mention of an agrichemical does not constitute a recommendation, merely the sharing of research findings. Always follow the label. The label is the law. Find out more at ipm.ucanr.edu.
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UCCE Upcoming Events - SAVE THE DATES:
- No-Till/Reduced Till Rice Field Day, June 10, 2025
- Rice Production Workshop, POSTPONED TO MARCH 2026
- Weedy Rice Workshop, August 5, 2025
- Rice Field Day, August 27, 2025
Other Resources
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
SPEAKER_02 (00:00):
Hello and welcome to Thoughts on Rice, a podcast
hosted by the University ofCalifornia Cooperative Extension
Rice Advisors.
I'm one of your hosts, SarahMarchionish, and I'm a rice farm
(00:21):
advisor for Colusa and Yolocounties.
SPEAKER_00 (00:24):
I'm Whitney from DeForest.
I'm the Cooperative ExtensionRice Advisor for Sutter, Yuba,
Placer, and Sacramento counties.
SPEAKER_04 (00:32):
My name is Luis Espino.
I'm the Rice Farming SystemsAdvisor for Butte and Glynn
counties.
I'm Michelle
SPEAKER_03 (00:40):
Leinfelder-Miles.
I'm a Farm Advisor in the Deltaregion.
I work on all sorts of fieldcrops, grains and forages.
but one of those is rice.
And the counties that I coverare San Joaquin, Sacramento,
Yolo Solano, and Contra Costacounties.
SPEAKER_02 (00:57):
Together, the UCCE Rice Farm Advisors seek to
provide relevant, topical,research-backed information
relating to California riceproduction.
Today I have the privilege ofsitting down with Dr.
Qasim Al-Khatib, who's theMelvin D.
(01:18):
Andros Endowed Professor forWeed Science and Specialist in
Cooperative Extension at UCDavis.
Qasim's career started with aBachelor of Science in Agronomy
from the University of Baghdad,followed by a PhD at Kansas
State University, after which hespent time in Extension and
Research at Washington State andKansas State before heading west
(01:41):
to UC Davis.
Qasim's Thank you.
(02:13):
and the environment.
Kasim is responsible for theherbicide resistance screening
program that the UC CooperativeExtension provides, free of
charge to rice growers and PCAswho are interested in
determining the herbicideresistance status of their rice
weeds.
I've asked Kasim to talk aboutthe herbicide resistance
screening process and tips forweed managers when it comes to
(02:36):
collecting and submitting weedsamples for testing.
(02:59):
Hi, Kasim.
Thanks for making the time to behere today.
Hi,
SPEAKER_01 (03:02):
Sarah.
SPEAKER_02 (03:03):
Let's talk a bit about your background and
education and how you came to behere at UC Davis.
SPEAKER_01 (03:09):
Yeah, I am here in UC Davis as a professor of weed
science and also weedspecialist.
Before that, I was the statedirector for UC IPM program.
And before that, I was aprofessor at Kansas State
University.
That's the place I went toschool to I spent about 15 years
(03:32):
there.
But before going to K-State, Iwas also a weed specialist at
Washington State University.
Currently, I do research,teaching, and extension.
My research focus on weedbiology and weed management,
herbicide-resistant weed, andoff-target herbicide movement,
(03:55):
which many people call itherbicide drift.
taught many classes, includingweed science, herbicide
interaction, integrated weedmanagement, integrated pest
management, physiology ofherbicide resistance.
I also supervise graduatestudent and postdoc, in addition
(04:17):
to do extension work with thegrowers on different aspects of
weed management.
SPEAKER_02 (04:22):
All that to say, Kasim, I think you stay pretty
busy.
Well, you mentioned herbicideresistance, and that's kind of
why we're talking today.
As we all know, the state ofherbicide resistance in
California rice weeds isprobably one of the highest, at
least in the United States.
So let's talk about howherbicide resistance typically
(04:43):
develops in plants.
SPEAKER_01 (04:45):
Sure.
Well, herbicide resistance meansthat the weed withstand
herbicide treatment, whichoriginally is susceptible to.
So the weed develop resistance.
Now the question, how how thathappened.
You know, when you take onesingle weed, take a population
of that weed, phenotypically,they look the same.
(05:08):
But if you look at this plant,and if you take a million of
these plants, you will find afew plants, maybe one plant in a
million, has slightly differentgenetic background.
And with this geneticbackground, that single plant
can survive herbicide treatment.
So when a grower or a personkeep using that herbicide, the
(05:34):
herbicide will kill all thesusceptible plants over time.
It's not going to take one yearto do it, but if you do it over
time, will it clean thesusceptible plant?
And what you have left is thatsingle plant I talk about it,
which has a genetic makeup thatresists the herbicide.
That single plant will produceseed and over time build the
(05:57):
population and that populationis resistant to the herbicide
now how that happened well it'sa species dependent some species
they have more genetic diversitythan others those these are the
species that will developresistant wicker if the grower
(06:19):
continue use the same herbicideor herbicide belong to the same
mode of action that willaccelerate the rate of
development of resistance.
If the grower does not do croprotation, which we're going to
talk about that, that also canlead to faster resistant
(06:41):
development.
In addition, if the persondoesn't use other method of weed
control, mechanical, cultural,good cultural practices,
biological, all these lead todevelopment of resistant
equator.
SPEAKER_02 (06:56):
Great answer.
And I'm glad you touched on croprotation.
and how it can affect herbicideresistance.
Because I do want to talk aboutrotation in general and not just
crop rotation, but also rotatingthe modes of action when it
comes to the chemicals you'reusing.
Can you talk about how rotatingmodes of action can help fight
against the rise of resistancein weeds?
SPEAKER_01 (07:19):
Well, if you take rice, for example, this is the
crop we're talking about here.
We have probably 12 differentherbicide regions table on rice.
Six of those belong to the samemode of action.
So if we develop resistance toone of these six, in general,
(07:40):
they will develop resistance tothe other six of the herbicides.
So you lost half of what youhave in your hand because of
this resistance.
So probably the good way to useherbicide is to rotate the mode
of action.
Don't rely on one mode of actionand you repeat using that mode
(08:03):
of action.
Other thing you could do ismixing two herbicides with two
different mode of action thatthey can kill that weed.
And with that also, we will helppreventing or delaying
resistance.
This is for chemical standpoint.
Rotation for crops also canhelp.
(08:24):
And I fully understand in ricewe have limitation because the
soil is heavy, does notaccommodate different crops, but
anytime you do a crop rotation,you delay the resistance.
This is another thing you needto do if you can.
(08:44):
Other factor that you canconsider is to control weeds
before you plant rice, which wecall it the still seed bed.
I know this is difficultsometimes because of weather
conditions, but this also willhelp because you can get rid of
the weeds before they grow inthe crop.
SPEAKER_02 (09:04):
And for people who might be less familiar with the
stale seedbed, let's go into, Iguess, how that looks in our
rice systems.
SPEAKER_01 (09:12):
Well, in rice systems, you know, what you need
to do is there are multiple waysyou can do it.
One way is after you work theground, there are weeds that are
going to come up.
You can flush the field withwater or even if you get enough
rain, weeds will emerge.
(09:32):
And what you need is to come andcontrol these weeds.
You can control them chemically.
You can control them by diskingthe ground.
And that will reduce the levelof weeds in your crop, in the
unseasoned crop.
SPEAKER_02 (09:47):
Thanks for clarifying that.
Now, just to kind of narrow inon California rice, because
that's what we're going toreally focus on here.
Let's talk about why herbicideresistance is such a huge
problem in California rice inparticular compared to other
systems.
SPEAKER_01 (10:05):
Sure.
I think it's a very seriousproblem here in California.
It's affecting thesustainability of the rice
cropping system.
As I said earlier, we had about12, 13 herbicides and half of
them belong to one mode ofaction.
We do not use quite a bit ofcrop rotation.
(10:28):
There is no many weed controlmethods.
Our growers are very good.
They use a clean seeds, so theydon't introduce weeds to their
field.
They control weeds on thelevees, ditches.
They use high seeding rate tosuppress weeds.
They use water, another thing,you know, deep water, so they
(10:51):
suppress weeds.
So they use multiple things.
But herbicide, you know,continue to be the main method
of weed control.
And as I said earlier, we don'thave too many herbicides.
And when growers continue youuse the same mode of action, it
will result of resistance.
We did quite a bit of researchand we found that we do have
(11:14):
resistance in certain populationto two, three, four, even five
mode of actions.
So this is a challenging tocontrol these weeds with
multiple resistance to multipleherbicide.
But again, you know, notrotating herbicide, no crop
rotation, limit methods of weedcontrol all led to this serious
(11:38):
problem in California rice.
SPEAKER_02 (11:42):
Absolutely.
I'm really glad you summarizedit like that.
But because I guess there's beensuch a history of strenuous weed
populations in California rice,weeds that are able to overcome
essentially everything that thegrowers and researchers have
thrown at them, is that part ofthe reason why the herbicide
resistance testing program thatyou currently have head up
(12:05):
began?
SPEAKER_01 (12:06):
Yes, that's absolutely right.
You know, we try to help thegrowers to identify what
resistance they have.
This is a key point inmanagement.
You need to know what resistanceyou have so you know what
herbicide to use to controlweeds.
You know, instead of trial anderror, instead of shooting in
(12:28):
the dark, they will have datathat they can rely on and use
the right herbicide to controlthese weeds.
SPEAKER_02 (12:38):
How long has the program been open to growers and
PCAs?
SPEAKER_01 (12:41):
Well, it was a program in a place for some
time.
But in 2015, we start this, youknow, extensive program.
You know, this program, as Isaid, 2015, we start.
It's supported by the RISEResearch Board, California RISE
Research Board.
So we started actually in 2015.
(13:05):
the modifier program.
Before that, we did some testinghere and there, but we didn't
have really a formal program.
SPEAKER_02 (13:15):
Okay, that makes a lot of sense.
So since you talked about theformal program, can you explain
the steps that are involved frombeginning, from a weed manager
or a grower seeing suspectedherbicide resistance in the
field, all the way to the end ofwhat that process looks like?
SPEAKER_01 (13:34):
Sure.
So if the farmer or the PCAthink they have resistance, they
collect seeds.
And probably we'll talk aboutthat later on.
But they collect seeds.
They take it to the UC farmadvisors or they bring it to the
RISE experimental station inBix.
(13:57):
We require a certain amount ofseeds.
We require the seeds to bemature.
and quality seeds, then some ofthe weeds, they have dormancy.
They don't germinate.
So we break the dormancy forthese weeds.
We have our method, what we doto break the dormancy.
(14:18):
After we break the dormancy,then we grow these plants in the
greenhouse and we treat a weed,a certain weed, every weed
actually, a species, with theherbicide label on that weed.
So if If we have watered grass,for example, we treat it with
(14:39):
all herbicide that's supposed tocontrol watered grass.
And then we look at the responseof the weeds.
And in the end, we take data forthe response.
We take photo for the responseof this population.
And then we send a report to thegrower to tell her or him, this
(15:00):
is the resistance you have.
This is the herbicide thatcontrol your weed, and this is
the herbicide you need to avoidthem because your weed has
resistance to these herbicides.
This is kind of summarized whatwe do, but there are a lot of
details in between.
SPEAKER_02 (15:17):
I guess in order to make sure that, say I'm a grower
and I'm going and collecting myseed, to get the most important
information out of that report,getting that good quality seed,
like you mentioned, is reallyvital.
But since the weed seeds matureat different points throughout
the season, you guys must bereceiving seed sample
(15:38):
submissions probably all riceseason, probably a little bit
after harvest has begun, huh?
SPEAKER_01 (15:44):
We have directions to the growers.
It's on the EOC RISE website,how they collect the seeds.
The website also has a video howyou do that.
So we ask growers to collectseeds at maturity and take a a
(16:04):
paper sack, put them by the headof the weed and put the head in
the back and try to shake thehead and the head will drop the
mature seeds in the back.
So we will have seeds for us totest it.
Now, we ask also growers to becareful because some of the weed
shatter early.
(16:26):
So they may need to collectthese weeds before they shatter.
So for example, springle top, itshatter quickly after the panic
will develop.
So they need to pick thoseseeds.
Then you have early water grasscome after that.
Barren yard grass come afterthat.
(16:47):
And then you have the commonweeds like the small flower,
bulrush.
And in the end, you have latewater grass.
So they need to go after theseweeds in the right stage so you
don't collect them and also youdon't allow them to shatter and
(17:09):
then you don't have seeds tocollect.
If they collect green seeds andsend this to us, there's two
things can happen.
The seed can rot in the back orthey will not germinate and that
create a problem.
And we have some cases where wetold the growers or PCA that
(17:30):
your seed was not good qualityand we cannot give you the
SPEAKER_02 (17:33):
results.
That makes sense.
So there are a couple of reasonsthen that a sample might be
unusable.
SPEAKER_01 (17:41):
Correct, correct, correct.
SPEAKER_02 (17:43):
And then when you send the report, let's talk
about just like confidentiality.
Who sees a report that gets sentin the program?
SPEAKER_01 (17:52):
Well, as I said earlier, generally growers give
us the seeds sometime lateSeptember, early October.
By end of October, we start theprocess of doing the screening
as I described earlier.
Then in the end, we will havethe results and send it to the
(18:16):
growers.
This is very confidential.
We ask the grower to give ussome information, some sort of
where is the field is, what'sthe history of the field, what
herbicide they use in the field,and that will help us in making
decision and recommendation tothe grower.
What's their contactinformation, their phone number.
(18:37):
If we run into a problem, wecall the grower or PCA to tell
them this is a problem we'refacing.
And to answer your question,it's very confidential between
us and the person who sent usthis.
Nobody else will see theresults.
SPEAKER_02 (18:56):
Fantastic.
Right.
I know that there's been somestate or countywide reporting of
resistance, but it's never tiedto an individual field or an
individual grower.
I think the most localized itgets is countywide basis.
SPEAKER_01 (19:10):
Sure, sure.
And one thing I didn't mentionthat we tried to send the
results to the growers sometimein mid-March so they can make
decision about what to use forthe coming season because they
need to buy chemical, they needto make an order, and with that,
we will give them theinformation.
(19:31):
For example, this year, we sentthe last report two days ago.
So all the growers receivedtheir report.
They know what resistant theyhave and they know what
chemicals they need to buy.
SPEAKER_02 (19:45):
Sounds great.
Sounds very valuableinformation.
I guess from a more researchstandpoint, let's move on and
talk about some of the mostimportant lessons that we've
learned from the herbicideresistance testing program as a
whole.
SPEAKER_01 (19:59):
Well, that's a good question, Sarah.
You know, we get samples like itdepends on the year.
Some year we get more than 100samples.
Some of them we get about 40,50.
It depends on the year, whatthey face, and so forth.
Half of the sample we received,they show no resistance.
(20:19):
And what does this tell us?
That there is other issue thatthe farmer did not get good
control of the weeds with theherbicide they use.
It could be environmental, couldbe the way they surprise the
chemical, the timing of theapplication.
There's multiple things cancause this lack of response.
(20:43):
But half of the cases, most ofthe time we see resistance at
least one mode of action.
So the lesson we learned that wedo have extensive herbicide
resistant spread across allcounties.
Some of the resistance aremultiple resistance.
Some of them resistant to morethan three or four herbicide,
(21:06):
which is difficult to manage atthis stage.
We're working on alternatives.
We're working on recommendation,what we need to tell these
people what to use.
And when they receive the reportof roma, us, we give them this
information.
You know, we recommend certainthings to the growers to
consider.
SPEAKER_02 (21:27):
Where can people who are interested find the
herbicide testing form?
And is there a website or aplace you want to direct them to
to look for it?
SPEAKER_01 (21:38):
Yeah, if you go to the to Google you see rice
website it will take you to thewebsite and you can click on the
weeds and under that type of theweeds you see multiple
information there.
One of them about herbicidescreening.
(22:00):
So the website for the UC ricewhich is
agronomy-rice-ucdavis.com or ifyou want to go directly to that
website which has theinformation about herbicide
resistance screening, you can goto agronomy-rise-ucdavis.edu
(22:27):
backslashresistant-weed-seed-testing.
You can get the information, allthe forms, all the information
how you pick the seeds.
And of course, I don't know ifwe talk about this, you need to
take the seeds either to theoffice of your farm advisors, or
(22:50):
you bring it directly to theRISE experiment station.
We have a box at the door whereyou put the sample and the form.
And in three, four months afterthat, you will get the result
from us.
SPEAKER_02 (23:06):
Yep.
And I did just double check withDustin Harrell at the station on
Tuesday, they will have that boxup and ready to accept
submissions when the seasonstarts.
And if no one's there, you canjust leave it.
We're up at the station, atleast one of us every day or so.
So somebody will get it.
All right, Kasim, is thereanything else you'd like to
(23:29):
touch on with this program?
You've given us a lot to chew onhere.
SPEAKER_01 (23:33):
Well, I think we're pretty excited about this
program.
We think if you have resistance,if you lack control, then you
give us a sample.
We will help you to make adecision to select the right
herbicide.
Also, my recommendation to thegrowers, use all the tools you
(23:54):
have in hand.
Don't forget good quality seeds,clean seeds, high seeding rate,
good water management, controlweeds on the levees and the
ditches.
All these will help you toreduce the impact of weeds on
your crop and also delay theresistance.
SPEAKER_02 (24:14):
Fantastic summary, Kasim.
Can I ask you to share yourcontact information if anybody
wants to reach out to youfurther?
SPEAKER_01 (24:21):
Well, you can send me an email klkatib at
ucdavis.edu or you can call meat 530-219 And I enjoy it when
growers call me about theproblem.
SPEAKER_02 (24:40):
I've seen you at the grower meetings, Kasim.
It's hard to get you to stophaving conversations with
growers sometimes.
All right.
And then with that, I thinkwe'll just wrap up with a final
question.
Don't worry, this one's not aserious question, but it might
be the hardest one to answer.
What is your favorite rice toeat, Kasim?
SPEAKER_01 (25:01):
Well, I like the Carlos rice.
It's sticky.
It's tasty.
It stays fresh for a longerperiod of time.
So this is my favorite rice toeat.
SPEAKER_02 (25:14):
Fantastic.
Thank you.
Wow, you had that answer allready to go.
Okay, Kasim, thank you verymuch.
And we will have you back on thepodcast soon.
SPEAKER_01 (25:24):
Pleasure.
My pleasure.
Thank you for inviting me.
SPEAKER_02 (25:44):
We've got quite a few save the dates here that I'm
going to go over.
The first is the no-till slashreduced-till rice field day, and
that'll take place Tuesday, June10, 2025.
The location for this will be inGrimes at the Gallagher Farm
site, and we'll release thatinformation as the time comes
(26:05):
closer.
But essentially, this field daywill be an opportunity for UC
researchers to share what we'vebeen learning about using
reduced tillage or Again, that'sthe No-Till, Reduced-Till Rice
Field Day, Tuesday, June 10th.
The next upcoming event will bethe Rice Production Workshop.
(26:28):
That's a two-day event.
That's Wednesday and Thursday,July 23rd and the 24th.
And that's going to be aworkshop where we talk about the
principles and practices of riceproduction in California.
This workshop only comes aroundevery two years, so we're very
excited about this.
And the location of that isstill TBD.
(26:50):
We'll also be hosting a weedyrice workshop on Tuesday, August
5th, 2025.
That location is also to bedetermined, but it will be in
the Delta.
And this workshop will talkabout all of the current UC
research regarding weedy rice inCalifornia rice systems.
Finally, the California RiceField Day will take place
(27:12):
Wednesday, August 27, 2025 atthe California Rice Experiment
Station in Biggs, California.
If you've been to this before,you know it's a pretty much
all-day event, a greatopportunity to not only see the
UC research, but also theresearch that the rice breeders
are undertaking up at the RiceExperiment Station, as well as
(27:33):
the opportunity to partake in adelicious lunch.
Again, that's the Rice FieldDay, Wednesday, August 27th at
the Rice Experiment Station inBiggs.
For more information about theseand upcoming events, feel free
to check out our resources,which include the UC Rice blog
(27:54):
and the UC Agronomy Ricewebsite.
In terms of other resources youmight like to take advantage of,
you can also look at ournewsletters, which include Rice
Briefs, which covers Colussiolo,Rice Notes, which covers Yuba
Sutter, Rice Leaf, which coversButan Glen, and Field Notes,
(28:14):
which covers rice in the DeltaReef.
in the region.
Thanks for listening to Thoughtson Rice, a University of
California Cooperative Extensionpodcast from the University of
California Agriculture andNatural Resources.
You can find out more about thispodcast on our website,
(28:35):
thoughtsonrice.buzzsprout.com.
We'd love to hear from you,whether it's from using our text
link in the show notes, a surveysubmission in our feedback form,
also in the show notes, or in acomment or rating on your
podcast Thank you.
Thank you.
(28:56):
Thank you.
In this area, we've seen growersstarting their field prep, and
(29:20):
so we know that rice planting isjust around the corner.
Stay safe out there, andremember, like the growers like
to say, have a rice life.
Mention of an agrochemical doesnot constitute a recommendation,
merely the sharing of researchfindings.
Always follow the label.
(29:41):
The label is the law.
Find out more at ipm.ucano Thankyou.
Hello and welcome to Thoughts on Rice, a podcast
hosted by the University ofCalifornia Cooperative Extension
Rice Advisors.
I'm one of your hosts, SarahMarchionish, and I'm a rice farm
(00:21):
advisor for Colusa and Yolocounties.
SPEAKER_00 (00:24):
I'm Whitney from DeForest.
I'm the Cooperative ExtensionRice Advisor for Sutter, Yuba,
Placer, and Sacramento counties.
SPEAKER_04 (00:32):
My name is Luis Espino.
I'm the Rice Farming SystemsAdvisor for Butte and Glynn
counties.
I'm Michelle
SPEAKER_03 (00:40):
Leinfelder-Miles.
I'm a Farm Advisor in the Deltaregion.
I work on all sorts of fieldcrops, grains and forages.
but one of those is rice.
And the counties that I coverare San Joaquin, Sacramento,
Yolo Solano, and Contra Costacounties.
SPEAKER_02 (00:57):
Together, the UCCE Rice Farm Advisors seek to
provide relevant, topical,research-backed information
relating to California riceproduction.
Today I have the privilege ofsitting down with Dr.
Qasim Al-Khatib, who's theMelvin D.
(01:18):
Andros Endowed Professor forWeed Science and Specialist in
Cooperative Extension at UCDavis.
Qasim's career started with aBachelor of Science in Agronomy
from the University of Baghdad,followed by a PhD at Kansas
State University, after which hespent time in Extension and
Research at Washington State andKansas State before heading west
(01:41):
to UC Davis.
Qasim's Thank you.
(02:13):
and the environment.
Kasim is responsible for theherbicide resistance screening
program that the UC CooperativeExtension provides, free of
charge to rice growers and PCAswho are interested in
determining the herbicideresistance status of their rice
weeds.
I've asked Kasim to talk aboutthe herbicide resistance
screening process and tips forweed managers when it comes to
(02:36):
collecting and submitting weedsamples for testing.
(02:59):
Hi, Kasim.
Thanks for making the time to behere today.
Hi,
SPEAKER_01 (03:02):
Sarah.
SPEAKER_02 (03:03):
Let's talk a bit about your background and
education and how you came to behere at UC Davis.
SPEAKER_01 (03:09):
Yeah, I am here in UC Davis as a professor of weed
science and also weedspecialist.
Before that, I was the statedirector for UC IPM program.
And before that, I was aprofessor at Kansas State
University.
That's the place I went toschool to I spent about 15 years
(03:32):
there.
But before going to K-State, Iwas also a weed specialist at
Washington State University.
Currently, I do research,teaching, and extension.
My research focus on weedbiology and weed management,
herbicide-resistant weed, andoff-target herbicide movement,
(03:55):
which many people call itherbicide drift.
taught many classes, includingweed science, herbicide
interaction, integrated weedmanagement, integrated pest
management, physiology ofherbicide resistance.
I also supervise graduatestudent and postdoc, in addition
(04:17):
to do extension work with thegrowers on different aspects of
weed management.
SPEAKER_02 (04:22):
All that to say, Kasim, I think you stay pretty
busy.
Well, you mentioned herbicideresistance, and that's kind of
why we're talking today.
As we all know, the state ofherbicide resistance in
California rice weeds isprobably one of the highest, at
least in the United States.
So let's talk about howherbicide resistance typically
(04:43):
develops in plants.
SPEAKER_01 (04:45):
Sure.
Well, herbicide resistance meansthat the weed withstand
herbicide treatment, whichoriginally is susceptible to.
So the weed develop resistance.
Now the question, how how thathappened.
You know, when you take onesingle weed, take a population
of that weed, phenotypically,they look the same.
(05:08):
But if you look at this plant,and if you take a million of
these plants, you will find afew plants, maybe one plant in a
million, has slightly differentgenetic background.
And with this geneticbackground, that single plant
can survive herbicide treatment.
So when a grower or a personkeep using that herbicide, the
(05:34):
herbicide will kill all thesusceptible plants over time.
It's not going to take one yearto do it, but if you do it over
time, will it clean thesusceptible plant?
And what you have left is thatsingle plant I talk about it,
which has a genetic makeup thatresists the herbicide.
That single plant will produceseed and over time build the
(05:57):
population and that populationis resistant to the herbicide
now how that happened well it'sa species dependent some species
they have more genetic diversitythan others those these are the
species that will developresistant wicker if the grower
(06:19):
continue use the same herbicideor herbicide belong to the same
mode of action that willaccelerate the rate of
development of resistance.
If the grower does not do croprotation, which we're going to
talk about that, that also canlead to faster resistant
(06:41):
development.
In addition, if the persondoesn't use other method of weed
control, mechanical, cultural,good cultural practices,
biological, all these lead todevelopment of resistant
equator.
SPEAKER_02 (06:56):
Great answer.
And I'm glad you touched on croprotation.
and how it can affect herbicideresistance.
Because I do want to talk aboutrotation in general and not just
crop rotation, but also rotatingthe modes of action when it
comes to the chemicals you'reusing.
Can you talk about how rotatingmodes of action can help fight
against the rise of resistancein weeds?
SPEAKER_01 (07:19):
Well, if you take rice, for example, this is the
crop we're talking about here.
We have probably 12 differentherbicide regions table on rice.
Six of those belong to the samemode of action.
So if we develop resistance toone of these six, in general,
(07:40):
they will develop resistance tothe other six of the herbicides.
So you lost half of what youhave in your hand because of
this resistance.
So probably the good way to useherbicide is to rotate the mode
of action.
Don't rely on one mode of actionand you repeat using that mode
(08:03):
of action.
Other thing you could do ismixing two herbicides with two
different mode of action thatthey can kill that weed.
And with that also, we will helppreventing or delaying
resistance.
This is for chemical standpoint.
Rotation for crops also canhelp.
(08:24):
And I fully understand in ricewe have limitation because the
soil is heavy, does notaccommodate different crops, but
anytime you do a crop rotation,you delay the resistance.
This is another thing you needto do if you can.
(08:44):
Other factor that you canconsider is to control weeds
before you plant rice, which wecall it the still seed bed.
I know this is difficultsometimes because of weather
conditions, but this also willhelp because you can get rid of
the weeds before they grow inthe crop.
SPEAKER_02 (09:04):
And for people who might be less familiar with the
stale seedbed, let's go into, Iguess, how that looks in our
rice systems.
SPEAKER_01 (09:12):
Well, in rice systems, you know, what you need
to do is there are multiple waysyou can do it.
One way is after you work theground, there are weeds that are
going to come up.
You can flush the field withwater or even if you get enough
rain, weeds will emerge.
(09:32):
And what you need is to come andcontrol these weeds.
You can control them chemically.
You can control them by diskingthe ground.
And that will reduce the levelof weeds in your crop, in the
unseasoned crop.
SPEAKER_02 (09:47):
Thanks for clarifying that.
Now, just to kind of narrow inon California rice, because
that's what we're going toreally focus on here.
Let's talk about why herbicideresistance is such a huge
problem in California rice inparticular compared to other
systems.
SPEAKER_01 (10:05):
Sure.
I think it's a very seriousproblem here in California.
It's affecting thesustainability of the rice
cropping system.
As I said earlier, we had about12, 13 herbicides and half of
them belong to one mode ofaction.
We do not use quite a bit ofcrop rotation.
(10:28):
There is no many weed controlmethods.
Our growers are very good.
They use a clean seeds, so theydon't introduce weeds to their
field.
They control weeds on thelevees, ditches.
They use high seeding rate tosuppress weeds.
They use water, another thing,you know, deep water, so they
(10:51):
suppress weeds.
So they use multiple things.
But herbicide, you know,continue to be the main method
of weed control.
And as I said earlier, we don'thave too many herbicides.
And when growers continue youuse the same mode of action, it
will result of resistance.
We did quite a bit of researchand we found that we do have
(11:14):
resistance in certain populationto two, three, four, even five
mode of actions.
So this is a challenging tocontrol these weeds with
multiple resistance to multipleherbicide.
But again, you know, notrotating herbicide, no crop
rotation, limit methods of weedcontrol all led to this serious
(11:38):
problem in California rice.
SPEAKER_02 (11:42):
Absolutely.
I'm really glad you summarizedit like that.
But because I guess there's beensuch a history of strenuous weed
populations in California rice,weeds that are able to overcome
essentially everything that thegrowers and researchers have
thrown at them, is that part ofthe reason why the herbicide
resistance testing program thatyou currently have head up
(12:05):
began?
SPEAKER_01 (12:06):
Yes, that's absolutely right.
You know, we try to help thegrowers to identify what
resistance they have.
This is a key point inmanagement.
You need to know what resistanceyou have so you know what
herbicide to use to controlweeds.
You know, instead of trial anderror, instead of shooting in
(12:28):
the dark, they will have datathat they can rely on and use
the right herbicide to controlthese weeds.
SPEAKER_02 (12:38):
How long has the program been open to growers and
PCAs?
SPEAKER_01 (12:41):
Well, it was a program in a place for some
time.
But in 2015, we start this, youknow, extensive program.
You know, this program, as Isaid, 2015, we start.
It's supported by the RISEResearch Board, California RISE
Research Board.
So we started actually in 2015.
(13:05):
the modifier program.
Before that, we did some testinghere and there, but we didn't
have really a formal program.
SPEAKER_02 (13:15):
Okay, that makes a lot of sense.
So since you talked about theformal program, can you explain
the steps that are involved frombeginning, from a weed manager
or a grower seeing suspectedherbicide resistance in the
field, all the way to the end ofwhat that process looks like?
SPEAKER_01 (13:34):
Sure.
So if the farmer or the PCAthink they have resistance, they
collect seeds.
And probably we'll talk aboutthat later on.
But they collect seeds.
They take it to the UC farmadvisors or they bring it to the
RISE experimental station inBix.
(13:57):
We require a certain amount ofseeds.
We require the seeds to bemature.
and quality seeds, then some ofthe weeds, they have dormancy.
They don't germinate.
So we break the dormancy forthese weeds.
We have our method, what we doto break the dormancy.
(14:18):
After we break the dormancy,then we grow these plants in the
greenhouse and we treat a weed,a certain weed, every weed
actually, a species, with theherbicide label on that weed.
So if If we have watered grass,for example, we treat it with
(14:39):
all herbicide that's supposed tocontrol watered grass.
And then we look at the responseof the weeds.
And in the end, we take data forthe response.
We take photo for the responseof this population.
And then we send a report to thegrower to tell her or him, this
(15:00):
is the resistance you have.
This is the herbicide thatcontrol your weed, and this is
the herbicide you need to avoidthem because your weed has
resistance to these herbicides.
This is kind of summarized whatwe do, but there are a lot of
details in between.
SPEAKER_02 (15:17):
I guess in order to make sure that, say I'm a grower
and I'm going and collecting myseed, to get the most important
information out of that report,getting that good quality seed,
like you mentioned, is reallyvital.
But since the weed seeds matureat different points throughout
the season, you guys must bereceiving seed sample
(15:38):
submissions probably all riceseason, probably a little bit
after harvest has begun, huh?
SPEAKER_01 (15:44):
We have directions to the growers.
It's on the EOC RISE website,how they collect the seeds.
The website also has a video howyou do that.
So we ask growers to collectseeds at maturity and take a a
(16:04):
paper sack, put them by the headof the weed and put the head in
the back and try to shake thehead and the head will drop the
mature seeds in the back.
So we will have seeds for us totest it.
Now, we ask also growers to becareful because some of the weed
shatter early.
(16:26):
So they may need to collectthese weeds before they shatter.
So for example, springle top, itshatter quickly after the panic
will develop.
So they need to pick thoseseeds.
Then you have early water grasscome after that.
Barren yard grass come afterthat.
(16:47):
And then you have the commonweeds like the small flower,
bulrush.
And in the end, you have latewater grass.
So they need to go after theseweeds in the right stage so you
don't collect them and also youdon't allow them to shatter and
(17:09):
then you don't have seeds tocollect.
If they collect green seeds andsend this to us, there's two
things can happen.
The seed can rot in the back orthey will not germinate and that
create a problem.
And we have some cases where wetold the growers or PCA that
(17:30):
your seed was not good qualityand we cannot give you the
SPEAKER_02 (17:33):
results.
That makes sense.
So there are a couple of reasonsthen that a sample might be
unusable.
SPEAKER_01 (17:41):
Correct, correct, correct.
SPEAKER_02 (17:43):
And then when you send the report, let's talk
about just like confidentiality.
Who sees a report that gets sentin the program?
SPEAKER_01 (17:52):
Well, as I said earlier, generally growers give
us the seeds sometime lateSeptember, early October.
By end of October, we start theprocess of doing the screening
as I described earlier.
Then in the end, we will havethe results and send it to the
(18:16):
growers.
This is very confidential.
We ask the grower to give ussome information, some sort of
where is the field is, what'sthe history of the field, what
herbicide they use in the field,and that will help us in making
decision and recommendation tothe grower.
What's their contactinformation, their phone number.
(18:37):
If we run into a problem, wecall the grower or PCA to tell
them this is a problem we'refacing.
And to answer your question,it's very confidential between
us and the person who sent usthis.
Nobody else will see theresults.
SPEAKER_02 (18:56):
Fantastic.
Right.
I know that there's been somestate or countywide reporting of
resistance, but it's never tiedto an individual field or an
individual grower.
I think the most localized itgets is countywide basis.
SPEAKER_01 (19:10):
Sure, sure.
And one thing I didn't mentionthat we tried to send the
results to the growers sometimein mid-March so they can make
decision about what to use forthe coming season because they
need to buy chemical, they needto make an order, and with that,
we will give them theinformation.
(19:31):
For example, this year, we sentthe last report two days ago.
So all the growers receivedtheir report.
They know what resistant theyhave and they know what
chemicals they need to buy.
SPEAKER_02 (19:45):
Sounds great.
Sounds very valuableinformation.
I guess from a more researchstandpoint, let's move on and
talk about some of the mostimportant lessons that we've
learned from the herbicideresistance testing program as a
whole.
SPEAKER_01 (19:59):
Well, that's a good question, Sarah.
You know, we get samples like itdepends on the year.
Some year we get more than 100samples.
Some of them we get about 40,50.
It depends on the year, whatthey face, and so forth.
Half of the sample we received,they show no resistance.
(20:19):
And what does this tell us?
That there is other issue thatthe farmer did not get good
control of the weeds with theherbicide they use.
It could be environmental, couldbe the way they surprise the
chemical, the timing of theapplication.
There's multiple things cancause this lack of response.
(20:43):
But half of the cases, most ofthe time we see resistance at
least one mode of action.
So the lesson we learned that wedo have extensive herbicide
resistant spread across allcounties.
Some of the resistance aremultiple resistance.
Some of them resistant to morethan three or four herbicide,
(21:06):
which is difficult to manage atthis stage.
We're working on alternatives.
We're working on recommendation,what we need to tell these
people what to use.
And when they receive the reportof roma, us, we give them this
information.
You know, we recommend certainthings to the growers to
consider.
SPEAKER_02 (21:27):
Where can people who are interested find the
herbicide testing form?
And is there a website or aplace you want to direct them to
to look for it?
SPEAKER_01 (21:38):
Yeah, if you go to the to Google you see rice
website it will take you to thewebsite and you can click on the
weeds and under that type of theweeds you see multiple
information there.
One of them about herbicidescreening.
(22:00):
So the website for the UC ricewhich is
agronomy-rice-ucdavis.com or ifyou want to go directly to that
website which has theinformation about herbicide
resistance screening, you can goto agronomy-rise-ucdavis.edu
(22:27):
backslashresistant-weed-seed-testing.
You can get the information, allthe forms, all the information
how you pick the seeds.
And of course, I don't know ifwe talk about this, you need to
take the seeds either to theoffice of your farm advisors, or
(22:50):
you bring it directly to theRISE experiment station.
We have a box at the door whereyou put the sample and the form.
And in three, four months afterthat, you will get the result
from us.
SPEAKER_02 (23:06):
Yep.
And I did just double check withDustin Harrell at the station on
Tuesday, they will have that boxup and ready to accept
submissions when the seasonstarts.
And if no one's there, you canjust leave it.
We're up at the station, atleast one of us every day or so.
So somebody will get it.
All right, Kasim, is thereanything else you'd like to
(23:29):
touch on with this program?
You've given us a lot to chew onhere.
SPEAKER_01 (23:33):
Well, I think we're pretty excited about this
program.
We think if you have resistance,if you lack control, then you
give us a sample.
We will help you to make adecision to select the right
herbicide.
Also, my recommendation to thegrowers, use all the tools you
(23:54):
have in hand.
Don't forget good quality seeds,clean seeds, high seeding rate,
good water management, controlweeds on the levees and the
ditches.
All these will help you toreduce the impact of weeds on
your crop and also delay theresistance.
SPEAKER_02 (24:14):
Fantastic summary, Kasim.
Can I ask you to share yourcontact information if anybody
wants to reach out to youfurther?
SPEAKER_01 (24:21):
Well, you can send me an email klkatib at
ucdavis.edu or you can call meat 530-219 And I enjoy it when
growers call me about theproblem.
SPEAKER_02 (24:40):
I've seen you at the grower meetings, Kasim.
It's hard to get you to stophaving conversations with
growers sometimes.
All right.
And then with that, I thinkwe'll just wrap up with a final
question.
Don't worry, this one's not aserious question, but it might
be the hardest one to answer.
What is your favorite rice toeat, Kasim?
SPEAKER_01 (25:01):
Well, I like the Carlos rice.
It's sticky.
It's tasty.
It stays fresh for a longerperiod of time.
So this is my favorite rice toeat.
SPEAKER_02 (25:14):
Fantastic.
Thank you.
Wow, you had that answer allready to go.
Okay, Kasim, thank you verymuch.
And we will have you back on thepodcast soon.
SPEAKER_01 (25:24):
Pleasure.
My pleasure.
Thank you for inviting me.
SPEAKER_02 (25:44):
We've got quite a few save the dates here that I'm
going to go over.
The first is the no-till slashreduced-till rice field day, and
that'll take place Tuesday, June10, 2025.
The location for this will be inGrimes at the Gallagher Farm
site, and we'll release thatinformation as the time comes
(26:05):
closer.
But essentially, this field daywill be an opportunity for UC
researchers to share what we'vebeen learning about using
reduced tillage or Again, that'sthe No-Till, Reduced-Till Rice
Field Day, Tuesday, June 10th.
The next upcoming event will bethe Rice Production Workshop.
(26:28):
That's a two-day event.
That's Wednesday and Thursday,July 23rd and the 24th.
And that's going to be aworkshop where we talk about the
principles and practices of riceproduction in California.
This workshop only comes aroundevery two years, so we're very
excited about this.
And the location of that isstill TBD.
(26:50):
We'll also be hosting a weedyrice workshop on Tuesday, August
5th, 2025.
That location is also to bedetermined, but it will be in
the Delta.
And this workshop will talkabout all of the current UC
research regarding weedy rice inCalifornia rice systems.
Finally, the California RiceField Day will take place
(27:12):
Wednesday, August 27, 2025 atthe California Rice Experiment
Station in Biggs, California.
If you've been to this before,you know it's a pretty much
all-day event, a greatopportunity to not only see the
UC research, but also theresearch that the rice breeders
are undertaking up at the RiceExperiment Station, as well as
(27:33):
the opportunity to partake in adelicious lunch.
Again, that's the Rice FieldDay, Wednesday, August 27th at
the Rice Experiment Station inBiggs.
For more information about theseand upcoming events, feel free
to check out our resources,which include the UC Rice blog
(27:54):
and the UC Agronomy Ricewebsite.
In terms of other resources youmight like to take advantage of,
you can also look at ournewsletters, which include Rice
Briefs, which covers Colussiolo,Rice Notes, which covers Yuba
Sutter, Rice Leaf, which coversButan Glen, and Field Notes,
(28:14):
which covers rice in the DeltaReef.
in the region.
Thanks for listening to Thoughtson Rice, a University of
California Cooperative Extensionpodcast from the University of
California Agriculture andNatural Resources.
You can find out more about thispodcast on our website,
(28:35):
thoughtsonrice.buzzsprout.com.
We'd love to hear from you,whether it's from using our text
link in the show notes, a surveysubmission in our feedback form,
also in the show notes, or in acomment or rating on your
podcast Thank you.
Thank you.
(28:56):
Thank you.
In this area, we've seen growersstarting their field prep, and
(29:20):
so we know that rice planting isjust around the corner.
Stay safe out there, andremember, like the growers like
to say, have a rice life.
Mention of an agrochemical doesnot constitute a recommendation,
merely the sharing of researchfindings.
Always follow the label.
(29:41):
The label is the law.
Find out more at ipm.ucano Thankyou.
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