September 29, 2025 • 43 mins
In this episode, Luis Espino and Sarah Marsh Janish give a rundown on stem rot, one of the main diseases of rice in California. One disease that can be found in practically every rice field is stem rot. This fungus causes the tillers to rot at the water level and, when severe, it causes blanking and lodging.
Stem Rot Resources
UC Rice Blog Post about Injury Thresholds
UCANR Stem Rot and Aggregate Sheath Spot Fact Sheet
Other Resources
Rice in the Delta
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
SPEAKER_01 (00:00):
Hello and welcome to Thoughts on Rice, a podcast
hosted by the University ofCalifornia Cooperative Extension
(00:21):
Rice Advisors.
I'm one of your hosts, SarahMarchionish, and I'm a Rice Farm
Advisor for Colusa and YoloCounties.
SPEAKER_00 (00:30):
I'm Whitney from DeForest.
I'm the Cooperative ExtensionRice Advisor for Sutter, Yuba,
Placer, and Sacramento counties.
SPEAKER_02 (00:37):
My name is Luis Espino.
I'm the Rice Farming SystemsAdvisor for Butte
SPEAKER_00 (00:43):
and Glynn counties.
I'm Michelle 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_01 (01:02):
Together, the UCCE Rice Farm Advisors seek to
provide relevant, topical,research-backed information
relating to California riceproduction.
In this episode, Luis Espinogives us a rundown on stem rot,
one of the main diseases of ricein California.
Now, one disease that can befound in practically every rice
(01:25):
field is stem rot.
This fungus causes the tillersto rot at the water level, and
when severe, it causes blankingand lodging.
Now, at the time of recording,the fields around us are, for
the most part, either startingto drain, well underway, or even
sort of starting to harvest the2025 crop.
(01:46):
This is the time of year when wetake our tiller samples to rate
for diseases like stem rot sothat we can evaluate the effects
of different fungicides appliedearlier this year at
approximately mid-tiller.
While this doesn't allow forrecommendations for the current
season, this does giveperspective and guidance on what
to expect in the coming season.
(02:08):
Here to tell us more about stemrot, some of the research
involving this disease.
Here's Louisa Spino.
(02:34):
Luis, thanks for making the timeto be here today.
I know it's a busy time of year.
SPEAKER_02 (02:38):
Yeah, well, it's coming to an end.
So it's, you know, there's lightat the end of the tunnel.
SPEAKER_01 (02:45):
Yeah, I have to say, I get really excited when I see
all the combines and the bankout wagons start to enter the
fields.
One, because it's an excitingtime of year and I love the
smell of rice harvest, but alsobecause it kind of indicates
that, okay, we're almost to thefinish line.
SPEAKER_02 (03:01):
We're getting to the end, yeah.
SPEAKER_01 (03:04):
So So Louise, I got to ask you here today because I
wanted to talk about stem rot,which is a disease we've been
talking about quite a bit theselast few weeks because you have
been in the midst, in the thickof doing stem rot ratings.
And so I thought it might be agood idea for us to hop on here,
talk a little bit about whatstem rot is.
(03:26):
And so for that, would you mindjust giving us a quick briefer
on what the symptoms of stem rotin rice are?
SPEAKER_02 (03:33):
Yes.
So stem rot is a very commondisease and is caused by a
fungus.
What happens is the pathogeninfects the tillers.
It starts with the leaf sheetsat the water level.
And then the lesions it causesare these black, blotchy spots
(03:54):
on the leaf sheets.
And as the disease gets moresevere, it penetrates those leaf
sheets into the tiller.
If it gets very severe, then itreaches the culm, which is the
main stem.
That's after you peel all theleaf sheets on a tiller, you end
(04:15):
up with the main stem.
That's what we call the culm.
And that gets infected.
And then that can get allrotted.
And once that happens, you startgetting a lot of blanks.
The stem, the tiller then alsobecomes weak and you see a lot
of lodging.
And so, yeah, those are kind ofthe symptoms and what the
(04:36):
disease causes.
SPEAKER_01 (04:37):
And so it's because that that stem becomes rotted or
overall weakened that it startsto fall over, starts to lodge
and might also bring some of thesurrounding plants down with it
as well, right?
SPEAKER_02 (04:49):
Yeah.
And it has a characteristiclook.
So, you know, a lot of times, alot of years we see a lot of
rice lodging and that's kind ofnormal, you know.
This year seems like we're nothaving, it's not going to be a
lodged year.
Like there's not a lot of ricedown.
I'm sure there'll be some.
But when it's caused by stemrot, it doesn't look flat.
(05:12):
So when the rice lodges,typically at the point where
it's rotted, the tiller, becauseof the stem rot, that's where it
will kind of bend.
And so it gives it a more, not auniform, but there's a pattern
to it.
So you see these ups and downson the field.
Some of the stems are kind ofup, but then the rest of the is
(05:35):
down.
And so that can be a pointer tothat what's causing it is not
just regular lodging, but causedby stem rot.
SPEAKER_01 (05:45):
Yeah.
I mean, we know stem rot'sincredibly common.
You see it in almost every ricefield.
But is there a reason why it'sso widespread?
I mean, how does the diseasespread once it's established?
SPEAKER_02 (05:59):
Well, that's a good question.
So typically, yes, we see stemrot in every field.
So the level of stem rot varies,but all fields have stem rot.
So it's pretty widelydistributed.
Now, I think over the years, thedisease can get worse because
what happens is the pathogen,when it grows inside in the
(06:22):
tiller and towards the end ofthe season, actually right now,
you know, if you pick up a fewtillers that have stem rot and
you peel them, you will seethese, they look like grains of
sand but they're black.
And those are the restingstructures of the pathogen.
Those are called the sclerotia.
And so these sclerotia are ableto survive in the residue and in
(06:48):
the soil as well.
And then as they accumulate,then the disease becomes more
severe.
And there's research from backin the, I believe it was maybe
the late 80s, where they did thework where they recovered the
sclerotia from the soil and thenrelated that to the level of
severity of disease in thefield.
(07:09):
And as you had more sclerotia,the disease was more severe.
And so over the years...
And this might be related to,you know, when we stopped
burning, this disease started tobecome more apparent.
Over the years, those sclerotia,you know, you accumulate them
(07:29):
and you get more and more ifyou're not doing anything to
avoid that development, right?
And so that's how you get tosome fields where you have high
levels of stem rot.
SPEAKER_01 (07:41):
So you're not doing anything to manage that residue
in a way that completelydeclines or removes it from the
field, the sclerotia are hardyenough to survive the winter,
reproduce, and potentially causemore of an infestation of stem
rot in the next year.
SPEAKER_02 (07:58):
Yeah, so those sclerotia, Bob Webster, who was
the pathologist, you know, backin the day, they determined that
sclerotia half-life is almosttwo years.
Wow.
So they can survive quite a bitof time in the soil.
And like I said, as theyaccumulate, then the disease is
(08:20):
worse and worse.
And so, you know, there was astudy they did where they would
have fields where they didn't doany straw management versus
fields where the straw wasincorporated and then the field
was winter flooded and otherfields.
Well, and then, yeah, and thenburning and other fields were
burned.
(08:41):
And so where you had the leastaccumulation of sclerotia was
where you were burning.
burning because you were gettingrid of all the residue,
including the sclerotium.
Then on the winter flooded, youknow, with the residue
incorporated, that was kind ofmedium.
And then where you had the mostaccumulation was in fields where
(09:02):
nothing was done.
The straw was left on thesurface and then just worked in
in the spring.
So that's where you had themost.
So, you know, and depending onthe winter, the, you know, the
degree of Decomp that you getvaries, and so the better decomp
you get, it helps reduce theamount of sclerotia.
(09:23):
And the other thing also, so thesclerotia survives in the straw.
It can also survive in the soil,but the sclerotia is going to be
in the straw.
And once we get into those maybelate February, early March days,
(09:43):
and it starts warming up, alittle bit, those sclerotia can
germinate and they feed on thatstraw and then produce more
sclerotia.
And so that's why it's soimportant to try to get rid of
that residue because then youdon't get that, you know,
increase that can happen duringthis, you know, late winter,
(10:04):
early spring.
SPEAKER_01 (10:05):
Okay.
Yeah.
So, I mean, it sounds likeburning used to be one of the
best ways for us to reduce theamount of...
inoculum in the soil.
Obviously, we've talked aboutthis before, you and I, earning
at least in large scale acreageis no longer that viable of an
option, at least in the vastmajority of the rice acreage.
(10:27):
I think CARB only allows about20% of the rice acreage.
And then there's a certainamount of acreage each county
gets.
And so it's definitelyeliminated.
Growers have had to look intodifferent methods of decomp in
order to remove their straw andtry to account for any disease
management
SPEAKER_02 (10:44):
Yeah.
And I think, you know, burning,I mean, we always knew that
burning was a positive in termsof disease management because,
you know, we were getting rid ofall that sclerotia.
And there's also aggregateshe-spot, which is another very
similar disease that also, youknow, survives via sclerotia in
the soil.
(11:06):
And then blast and to a pointback.
So, yeah, we always knew thatburning was good for disease
management.
But since we lost that, I thinkwe've seen disease management
become more important.
And maybe the impact of some ofthese diseases that in the past
(11:27):
were not that impactful, youknow, we're seeing them become a
little bit more concerning.
And so, yeah, the managementstrategy still is to try to do
the best you can when it comesabout managing straw and
(11:49):
decomposing straw, getting ridof that straw.
Now, you know, I don't thinkthere were any studies looking
at baling.
But baling can be very variable.
It depends on what height you'recutting that straw.
And even when you bale, you'recutting as low as you can,
there's going to be a lot ofresidue left in the field.
(12:10):
Theoretically, removing residuewith sclerotia would be
positive, but to what degree, Idon't know.
It's going to depend on how lowyou can go with the baling, how
low you can cut.
SPEAKER_01 (12:25):
And then what you do with your stubble as well.
And then that's just anotherpass to get in before winter.
So a lot to worry about.
SPEAKER_02 (12:32):
Right.
Maybe if you burn that stubble,that might work out to be as
effective as a burn, you know, aregular burn.
SPEAKER_01 (12:41):
And if you can't get in burning, maybe you stomp it,
I guess, if you can.
SPEAKER_02 (12:46):
Yeah.
But I don't know to what degree,you know, growers that are
baling, are they still, youknow, too concerned about trying
to get that stubble incorporatedWe've
SPEAKER_01 (12:59):
talked a bit about some of the management options
that are available.
And first and foremost, ofcourse, is just straw and straw
decomp.
But there's also a factor thatfertility can play, at least
when it comes to the incidenceof stem rot.
And I understand from some ofthe work that you and Bruce have
done is that excess nitrogen canactually increase the severity
(13:21):
of stem rot.
Would you care to touch on thata little bit?
SPEAKER_02 (13:24):
Yeah.
So, and yeah, and then again,we've talked a lot about the
importance of We've also knownthis from back from Webster's
days.
Yes, excess nitrogen.
So if you have high levels ofnitrogen, you will have higher
stem rot.
And you typically see it justlike with blast.
You see it on the headlandswhere there's overlaps.
(13:45):
That's where you would typicallysee more stem rot because you
have more nitrogen.
But the other nutrient that'simportant is potassium.
And I, you know, every time I...
I talk to growers and PCAs aboutstem rot.
I always tell this story where,you know, I was working with a
grower that had a really severestem rot field.
(14:09):
And, you know, yield was in the70s or so.
And, you know, we did trials fora couple of years, you know, try
different fungicides, differenttimings, and nothing seemed to
make a difference.
And then one year they realizedthey were low on potassium.
And so, and I didn't think ofthat, but they, you know,
(14:34):
addressed that issue andincreased their potassium
fertility to a level that, youknow, was recommended.
And then the stem rot kind ofwent away.
It didn't go away completely,but their yields went up, you
know, back to the 90s or so.
So, yeah, potassium is, it's areally important nutrient when
(14:54):
it comes to And does it matter?
I
SPEAKER_01 (15:13):
know in some of the work you've put out, you've
noted specifically that surfacesupply potassium fertilizer is
reported to reduce race stem rotdevelopment.
Is there any other types of stemrot?
of application of potassiumfertilizer that you've looked
at?
SPEAKER_02 (15:29):
Oh, I see.
Like thinking about maybe foliarfertilizers?
SPEAKER_01 (15:33):
Yeah.
Has there been anything you'velooked at with that?
SPEAKER_02 (15:37):
You know, no, we haven't.
I don't think there's any datashowing, I mean, any other type
of fertility that would, eitherway, like that works or not.
Yeah, the work that was doneearlier was looking at, well, I
would have to look at what theyused, but it was just, yeah, dry
(15:58):
fertilizer, you know.
What we don't know is, sousually we put the potassium
with the phosphorus either as a,you know, early before when
we're doing field work or youput it later, you know, about 20
days after planting because justto avoid the scum with the
(16:18):
phosphorus if, you know, mostlikely putting phosphorus as
well.
What we don't know if later alight potassium would be as
effective.
And that's out there and thatmight be something that might be
worth, you know, researching alittle bit because some cases
you don't realize that you havea deficiency or, you know, a
(16:41):
potassium or a stem rot issueuntil late in the season.
And so at that point, you know,would it be worth putting some
potassium in, you know, wouldthat correct some of the
deficiency?
We don't have, we don't know.
SPEAKER_01 (16:56):
And then another, I guess, cultural manage option
when it comes to stem rot isalso your varietal choices.
And I know that I think I'veread that the shorter season
varieties, your M105, your S102,Kalmochi 101, I think it is,
they might be more susceptibleto stem rot and the other
(17:18):
diseases rather than maybemid-season.
So 209, 210.
Is there a reason for that,Louise?
SPEAKER_02 (17:26):
Yeah, so I think it's just, we have with later
season varieties like N211, youhave a thicker, more
structurally strong tiller, sayan M105.
And yeah, we've seen that intrials.
We did that three years oftrials comparing varieties.
(17:50):
And we did see that thesevarieties with thicker tillers
had developed less stem rot.
They still developed it, but theseverity to which they developed
it was less than the thinnertiller varieties.
And also something to keep inmind is all the varieties have
(18:11):
different responses.
And so the varieties from therice experimentation when they
put them out they do have a stemrot score so one could compare
those scores you know or I don'tthink growers are going to
choose a variety based on thatbut you know you can see what
the score is to have an ideacompared to say an M206 or an
(18:34):
M210 but yeah I think in generalvarieties that have thicker
bigger stems or tillers tend todevelop less severe stem.
SPEAKER_01 (18:45):
I have heard that about 211, that it leaves a lot
of straw behind and it's gotreally thick stems.
So that makes sense.
It's possibly more structurallysound, more able to resist.
SPEAKER_02 (18:57):
Yeah, somehow, you know, we thought about it.
What could it be?
But I, you know, I don't have agood answer because the tiller
is...
There's nothing inside thetiller.
The tiller is just a structure,and then inside the tiller
there's nothing.
So it's not like the tiller isthicker.
They're all about the samethickness, but maybe just the
(19:23):
tiller being bigger allows theplant to be able to withstand
that stem rot better.
There's still some tissue bywhich the plant can move
nutrients up to fill thosekernels.
But anyway, but yeah, wemeasured tillers and we did find
that thinner meant higherseverity.
SPEAKER_01 (19:44):
So, I mean, there aren't a ton of options when it
comes to chemical control ofthese diseases.
In fact, I remember a talk yougave, I think last year, when
you were talking about fungicidetreatments and then your next
slide was just saying like, andbasically we've got quadris.
Because in California rice, it'spretty much is and occasionally
(20:08):
propiconazole, right?
SPEAKER_02 (20:11):
Yeah, and I don't think propiconazole has much of
an effect on stem rot.
But yeah, it's one activeingredient we have,
azoxystrobin.
And we've done quite a fewtrials over the years, and we do
see a reduction in severity.
It's not huge.
(20:33):
It's maybe a 20-30% reduction.
Especially when stem rotseverity is moderate to maybe
high.
But if it's very high, then it'svery difficult to control it, to
reduce that severity.
But anyway, yeah, withazoxystrobin, we can reduce the
(20:54):
severity when we apply thefungicide at the early heading
stage.
So sometime in between the, youknow, when you got that boot
split and the first few paniclesare visible above the canopy,
you know, that's about the timewhen, if you do an application,
(21:16):
you'll have a reduction inseverity.
For many years, you know, wethought that putting the
fungicide early, like maybe withPropanil, at Propanil time,
would be more effective.
Because at that time, you know,you don't have a canopy that's
as thick as later.
(21:36):
And so you can actually get thefungicide down at the water
level.
But all the trials we've done,rarely do we see a benefit when
we put it at that time.
So...
It could be that it's a littlebit too early.
Reviewing the information that'sout there, the stem rot seems to
(22:01):
be or infects the plant at aboutPI.
So, you know, propanil time is alittle earlier than that.
So maybe it's a little too earlyand there's not enough residual
effect to protect.
But the fact is, yes, we don'tsee much benefit early.
The benefit is at heading, earlyheading.
(22:21):
Which I think works well becausethat's also the blast timing,
you know, in case blast was aproblem.
SPEAKER_01 (22:30):
Two birds, one stone.
You're doing, taking care ofyour diseases at the same time.
SPEAKER_02 (22:34):
Yes.
Right.
SPEAKER_01 (22:35):
Or trying to, anyway.
SPEAKER_02 (22:36):
Yeah.
With, yeah, the other disease,you know, that's, like I said,
is similar, is aggregate sheath.
But that one, yes, you know, ifyou apply early, you're at
propanil time, the esoxystrobin,we do see a benefit there.
Aggregate she spot is mucheasier to control than stem rot,
(22:57):
I think.
We see a much higher efficacy ofthe fungicide when trying to
reduce aggregate she spotlevels.
And, you know, in general, wedon't have a lot of very severe
aggregate she spot, you know.
So the levels of disease thatare out there, it's not very
high.
(23:17):
So maybe that's why we see, youknow, more efficacy.
But yeah, it's a little easierto control.
to manage that.
But yeah, so yeah, that's thetiming for stem rot is early
hitting.
SPEAKER_01 (23:28):
And then when it comes to monitoring in your
fields and then figuring outwhen to treat, if you need to
treat at all, what does it meanwhen we say like, when do you
monitor for stem rot?
What does that look like?
And then do we have treatmentthresholds for this disease?
SPEAKER_02 (23:50):
Yeah, so the monitoring, you know, I've been
working on that for a few yearsnow.
And so typically the way wedetermine the severity level of
a field is we take samples atdrain time.
You know, we cut tillers, thenrate them, and then we know the
severity.
Now, you know, growers, PCAs,they're not going to do that
(24:12):
because it takes a lot of time.
And, you know, at that time, allyou get is information maybe for
next year.
Yes, there's a lot of stem rotin this field, you might want to
do a better job of strawmanagement or incorporate a
fungicide in your program orconsider that stem rot might be
(24:34):
an issue.
So what I've been doing istrying to relate stem rot
incidents early at about theboot stage, so before a
treatment would be done, withour ratings at drain time.
(24:55):
And there seems to be arelationship.
We're still doing it this year,so this might be the last year
we've done it.
But what we have done so far,I've seen that if you get about
half of your tillers with stemrot lesions at the boot stage,
then that's going to mean you'regoing to have a lot of, well,
(25:20):
100% of tillers with stem rot atdrain time.
So that would be a way to kindof monitor for stem rot, is you
can go at the boot stage, lookat your tillers, and if you're
seeing, 50% of them with stemrot, then you might want to
(25:41):
think, okay, maybe you need todo something.
And so we'll, you know, we'restill refining this.
Like I said, we're doing anotheryear of trials.
And hopefully, you know, nextyear or in a couple of years,
we'll have something more solid.
But that's what I've beensharing with the PCAs and
(26:04):
growers right now.
So about 50% at boot time.
Or if you're just looking atdrain time, you know, just kind
of checking things and seeing,you know, what the crop's going
to be like.
If all your tillers have stemrot lesions, you're probably at
a higher, at a high severity ofstem rot.
(26:28):
And so you might want toconsider, you know, trying to
burn or, you know, trying toreally up your straw management.
SPEAKER_01 (26:37):
And when you say that the tillers have lesions,
is there a certain severity ofthose lesions or severity of the
disease incidence that has anyrelation to that?
SPEAKER_02 (26:48):
No, just if you can just see the lesion, that, yeah,
that means that the disease isthere.
Yeah.
SPEAKER_01 (26:55):
So, Luis, when you say that we're doing ratings at
drain time for tillers, let'stalk about what that looks like.
What does it mean when we takethe crew out there and take a
bunch of tillers and then how dowe figure out how much stem rots
out there?
SPEAKER_02 (27:10):
Yeah.
Yeah.
And again, we do this forresearch purposes.
So this is not something that,you know, we would expect
growers or PCAs to do.
But so what we do is, you know,we have our plots and we go into
our plots.
We take three handful of tillersfrom different areas and then we
just randomly select 50 tillers.
(27:31):
And then each of these tillers,we start peeling them and
looking for stem rot lesions.
And so if we only find stem roton the outer leaf sheaths at the
water level, then we considerthat, we give that a rating of
one.
If we peel that and we see onthe next layer, the next leaf
(27:51):
sheath, you know, there's alesion there, then that would be
a level two.
And you continue peeling untilyou get to the, usually after
that you get to the main column,the main tiller.
And so once you get to the maincolumn, if you see a lesion on
that, then that's a level three.
(28:11):
And then if that column isrotted, so it's black all around
and you open it up and you cansee actually the white mycelia
growing inside, then we considerthat a level four.
And obviously if the tiller'shealthy, which we also find
(28:34):
healthy tillers those would bezeros and so that's how we rate
and so we rate then we count howmany tillers for each each level
and then we calculate like aweighted average sort of and
that gives us our severity indexand what we found is when we are
(28:55):
at a level two or more that'swhen you see very high numbers
of tillers will show lesions soso the incidence is very high
but you cannot differentiatejust looking at incidence or so
(29:16):
the number of tillers you knowthat are infected you cannot
differentiate between a two anda three just two and high two
and above it's always 100incidence so that's why we say
you know if you're 100 you'reprobably severity two or above
so it can be very severe Butlike I said, that's, you know,
we do that for research.
(29:37):
Now, you know, sometimes when wego out to the field, you know,
we show a grower, a PCA, what itlooks like.
You know, you can peel thoseleaf sheaths and then look at
the comb, and if it looks niceand clean, well, you can feel,
you know, comfortable that,yeah, the stem rot is not very
severe.
But if you start finding a lotof tillers with lesions in that
(29:58):
main comb, then that means that,yeah, there's, you know, that is
a severe stem Yeah.
SPEAKER_01 (30:05):
Thanks for explaining that, Luis.
So Luis, obviously you get a lotof like disease calls and
especially at this time of year,do you have, I guess, an
estimation or just a guess on ifthis is a high disease year or
if this is just kind of a lowlevel disease year across the
region?
SPEAKER_02 (30:24):
Well, I see.
In general, not just Tembra.
So You know, real quick,bacchani is still around.
Nothing that would, I think,affect yields, but still
something that's an eyesoreearly on.
You know, you see all theseplants that are, you know,
obviously affected by bacchaniand, you know, it can be a
(30:46):
concern.
But like I said, nothing thatwould cause a yield reduction.
Aggregate sheath spot istypically not a very important
disease.
So we see it every now and then,but I've never seen it very
severe as to be of concern.
Stem rot, you know, the fieldsthat have it, they will continue
(31:07):
to have it.
And fields that do not have it,they might increase or decrease.
You know, how severe stem rot iskind of tends to be, you know,
pretty stable.
Now, the other disease thatvaries quite a bit is blast.
And there's been some blast thisyear.
Most of the fields I've seenhave been in the northwest side
(31:31):
of the valley, so Glen Countynear Willows.
Some fields have been severelyaffected.
I think they're going to have ayield loss.
Other fields, there's justspots, you know, the nitrogen
overlaps.
That's where you see it.
There was some leaf blast earlyon.
(31:53):
I did not see it until later,until, you know, just last week
where I was looking at somefields.
But there was a little bit ofleaf blast.
And so...
We'll see in these fields ifthey actually see much of a big
yield loss, but some fields, thedisease came late, and so the
panicles were already, you know,filled.
(32:15):
So hopefully those are not goingto be too affected.
So overall, you know, up inWillow's area, yeah, blast was
present.
Everywhere else, I reallyhaven't seen much, any blast.
And SMOD, I have seen verylittle SMOD.
Very, very little.
(32:36):
So, yeah, best way to avoid SMODis let me put a trial in your
field.
So anyway, yeah, I think thoseare our main diseases.
SPEAKER_01 (32:50):
Yeah, we're pretty fortunate.
I mean, knock on wood, here inCalifornia, we don't have the
disease pressure that otherareas do and grateful for it.
But it always makes us a littlenervous, I think, if we do start
to see a bit of creep up anddisease like we did a couple of
years ago with that blastinfestation.
SPEAKER_02 (33:10):
Yeah, yeah, we're lucky.
So this is unrelated, but so inthe southern U.S., you know,
Louisiana, Texas, Arkansas, nowthey're finding this, the risal
facet, which transmits the...
And so now they have a newdisease they have to worry
about.
(33:31):
And, you know, hopefully wewon't have to worry about that.
But it's good to keep an eye outfor this bug.
SPEAKER_01 (33:39):
Luis, is there anything else you want to share?
Any upcoming events orinformation you want to share
with the crowd here?
SPEAKER_02 (33:47):
So, yeah, I was thinking that with this year,
you know, I had one experimentwhere I was looking at the
effects of COVID-19.
of top dress on Stambra.
And so, you know, some of thework that Bruce has done has
shown that it's better to putall your nitrogen up front as
aqua.
(34:08):
And if you don't need a topdress, then, you know, don't put
it.
If you typically put a topdress, instead of putting those
30 pounds of nitrogen, you know,at that time, just add your
aqua.
Increase your aqua by 30 unitsand don't top dress.
And some people have adoptedthat.
(34:28):
But I was wondering, well, doesthe top dress have any effect on
stem rot?
You know, because we're puttingthe nitrogen right about the
time when stem rot becomes to bea problem.
And so, yeah, I had a smalltrial, you know, at the station
in Biggs.
And I've looked at some of thedata.
(34:48):
And, you know, it's notsignificant, but in all the
plots where we put a top dress,the stem rot was slightly
higher.
And in plots where we didn't puta top dress, we just put all the
nitrogen initially as aqua.
So, you know, it was just a kindof, let's see what happens.
(35:09):
I think I'm going to do it againnext year.
Any
SPEAKER_01 (35:12):
events or anything, Luis, or any resources you want
to point people towards?
SPEAKER_02 (35:17):
Oh, well, so we have our fact sheets, you know, and
there's a fact sheet on tillerdiseases, so stem rot and
aggregate sheet spot.
There's a fact sheet on onpotassium as well.
And I've been directing growers'PCAs to those when we get calls
about disease management.
(35:38):
Yeah, and events, I don't thinkthat we have anything coming up
until our winter growermeetings, yeah.
SPEAKER_01 (35:48):
Okay, Luis.
Well, thank you so much formaking the time.
SPEAKER_02 (35:51):
All right.
Yeah, no problem.
This was fun.
SPEAKER_01 (36:16):
Now, we don't have any upcoming rice events, but
there is an upcoming event withthe UC Master Gardener program
based out of the Colusa office.
The Colusa UC Master Gardenerswill be hosting a pumpkin
centerpiece workshop just intime for the fall season on
Thursday, October 16th from 6 to8 p.m.
(36:38):
in the Colusa IndustrialProperties Conference Room.
Registration is required forthis event.
You can visit our office or callin to save your spots and you
better save your spot prettyquick because the spots for this
workshop go pretty quickly ifyou have any questions please
reach out the number is530-458-0570 there is a cost
(37:05):
associated with this workshop itis$30 per person and that
includes all supplies needed totake your lovely pumpkin
centerpiece home with you justin time for the fall season
We've also been asked to make anannouncement on behalf of the
Western Region Certified CropAdvisor Program, also known as
(37:26):
WRCCA.
They reached out to us to ask usto help celebrate some
accomplished individuals thatthey honored at the WRCCA annual
meeting this past week inVisalia, California.
The WRCCA program is committedto refining the knowledge and
skill of those making decisionsin the CCAs play a vital role
(37:49):
working with producers to ensuresustainability and long-term
success.
For more information, visitwrcca.org.
WRCCA announces the 2025 CCA ofthe Year and Alan Remander
Scholarship and Mentor Awardprogram winners.
The Award for Certified CropAdvisor of the Year in the
(38:11):
Western Region acknowledges themembers' exemplary dedication
and contributions to agricultureand WRCCA is excited to announce
the 2025 CCA of the Yearrecipient is Eric Pooler.
Eric's career has focusedspecifically on wine grape
production, spanning time withmany of the most distinguished
(38:31):
wineries and farming operationswithin the U.S.
wine industry.
Congratulations, Eric.
The Alan Romander Scholarshipand Mentor Awards Program honors
the life work of dedicatedagriculturalist and leader, Alan
Romander.
1941 to 2019.
Alan Romander was one of thefirst CCAs in California, and
(38:53):
his passion for agriculturecreated a lasting impact on
those around him.
We would like to congratulatethe following individuals for
receiving a scholarship.
In the South Valley, werecognize Carlos Vega Lara,
hailing from Parlier,California, and attending
Reedley Community College andmajoring in plant science.
Next year, he plans to transferto Fresno State to earn a
(39:15):
bachelor's in plant science witha minor in agronomy, while
gaining experience to take tothe certified crop advisor
exams.
In the North Valley, werecognize Reed Scott from Yuba
City, California, currentlypursuing a major in integrated
plant sciences at WashingtonState University.
His goals include obtaining aCCA, PCA, and QAL to further his
(39:38):
value in education in theindustry.
In the desert region, werecognize Joseph Clark from
Yuma, Arizona, presentlyenrolled at University of
Arizona with a major inagricultural systems management.
She plans to become a CCA as shegraduates in 2026.
In the coastal region, werecognize Roberto Lopez from
(39:59):
Oakdale, California, currentlypursuing a degree in
agricultural science with aminor in plant protection at
California Polytechnic StateUniversity San Luis Obispo.
Looking ahead, he plans tocontinue combining hands-on
farming experience withagribusiness insights to support
innovations sustainability, andworkforce development across
California agriculture.
(40:21):
We congratulate all thesescholarship winners for their
achievements.
Mentor awards are granted toexceptional professors who teach
agronomy-related coursework.
Our mentor award recipient isDelia Melendez, adjunct
professor of plant science atLos Angeles Pierce College.
Delia is a student of PierceCollege herself and has
(40:41):
associate degrees in bothhorticulture and landscape
design, and a bachelor's degreein horticulture from Oregon
State University, and abachelor's degree in
horticulture from Oregon StateUniversity.
Oregon State University.
With the honorarium grantfunding, the students will
benefit by applying it to twostudent projects at Pierce
College.
Both projects provide thestudents with opportunities to
(41:03):
experience hands-on learning andto gain knowledge about various
aspects of agronomy as appliedto a practical situation.
We congratulate the Mentor Awardrecipient, Delia Melendez.
WRCCA is proud to announce therecipient of the 2025
Distinguished Service Award Thisaward acknowledges a retired
(41:24):
certified crop advisor, CCA, whohas dedicated their career and
volunteer time to the CCAprogram in agriculture industry.
WRCCA is excited to announce the2025 Distinguished Service Award
recipient is Fred Strauss.
Fred Strauss began his career asa pest control advisor and was
(41:44):
an active member of theCalifornia Association of Pest
Control Advisors, or CAPCA.
He was recognized as a CAPCAmember of the year in 1991 for
the time and effort hegenerously gave to the
organization.
When the Certified Crop Advisororganization was established in
1992, he was among the first toget certified.
He was later asked to serve onthe CCA board, holding various
(42:06):
positions including chairman.
For many years, Straussspearheaded the marketing
efforts of the Western RegionCCA program, manning booths and
prioritizing the growth of theorganization.
He eventually began working withWestern Farm Service, which is
now known as Nutrien.
After retiring, he remainedengaged in the industry,
(42:27):
volunteering with theInternational Certified Crop
Advisor Board.
Advisor Strauss is well known inthe industry for his kind
demeanor, passion for the CCAprogram, and the ability to have
an engaging conversation witheach person he interacts with.
Congratulations to Fred Strauss.
(42:48):
Remember, Like the growers liketo say, have a rice life.
(43:16):
The material and informationpresented here is for general
purposes only.
The University of Californianame and all forms and
abbreviations are the propertyof its owner and its use does
not imply endorsement of oropposition to any specific
organization, product, orservice.
Hello and welcome to Thoughts on Rice, a podcast
hosted by the University ofCalifornia Cooperative Extension
(00:21):
Rice Advisors.
I'm one of your hosts, SarahMarchionish, and I'm a Rice Farm
Advisor for Colusa and YoloCounties.
SPEAKER_00 (00:30):
I'm Whitney from DeForest.
I'm the Cooperative ExtensionRice Advisor for Sutter, Yuba,
Placer, and Sacramento counties.
SPEAKER_02 (00:37):
My name is Luis Espino.
I'm the Rice Farming SystemsAdvisor for Butte
SPEAKER_00 (00:43):
and Glynn counties.
I'm Michelle 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_01 (01:02):
Together, the UCCE Rice Farm Advisors seek to
provide relevant, topical,research-backed information
relating to California riceproduction.
In this episode, Luis Espinogives us a rundown on stem rot,
one of the main diseases of ricein California.
Now, one disease that can befound in practically every rice
(01:25):
field is stem rot.
This fungus causes the tillersto rot at the water level, and
when severe, it causes blankingand lodging.
Now, at the time of recording,the fields around us are, for
the most part, either startingto drain, well underway, or even
sort of starting to harvest the2025 crop.
(01:46):
This is the time of year when wetake our tiller samples to rate
for diseases like stem rot sothat we can evaluate the effects
of different fungicides appliedearlier this year at
approximately mid-tiller.
While this doesn't allow forrecommendations for the current
season, this does giveperspective and guidance on what
to expect in the coming season.
(02:08):
Here to tell us more about stemrot, some of the research
involving this disease.
Here's Louisa Spino.
(02:34):
Luis, thanks for making the timeto be here today.
I know it's a busy time of year.
SPEAKER_02 (02:38):
Yeah, well, it's coming to an end.
So it's, you know, there's lightat the end of the tunnel.
SPEAKER_01 (02:45):
Yeah, I have to say, I get really excited when I see
all the combines and the bankout wagons start to enter the
fields.
One, because it's an excitingtime of year and I love the
smell of rice harvest, but alsobecause it kind of indicates
that, okay, we're almost to thefinish line.
SPEAKER_02 (03:01):
We're getting to the end, yeah.
SPEAKER_01 (03:04):
So So Louise, I got to ask you here today because I
wanted to talk about stem rot,which is a disease we've been
talking about quite a bit theselast few weeks because you have
been in the midst, in the thickof doing stem rot ratings.
And so I thought it might be agood idea for us to hop on here,
talk a little bit about whatstem rot is.
(03:26):
And so for that, would you mindjust giving us a quick briefer
on what the symptoms of stem rotin rice are?
SPEAKER_02 (03:33):
Yes.
So stem rot is a very commondisease and is caused by a
fungus.
What happens is the pathogeninfects the tillers.
It starts with the leaf sheetsat the water level.
And then the lesions it causesare these black, blotchy spots
(03:54):
on the leaf sheets.
And as the disease gets moresevere, it penetrates those leaf
sheets into the tiller.
If it gets very severe, then itreaches the culm, which is the
main stem.
That's after you peel all theleaf sheets on a tiller, you end
(04:15):
up with the main stem.
That's what we call the culm.
And that gets infected.
And then that can get allrotted.
And once that happens, you startgetting a lot of blanks.
The stem, the tiller then alsobecomes weak and you see a lot
of lodging.
And so, yeah, those are kind ofthe symptoms and what the
(04:36):
disease causes.
SPEAKER_01 (04:37):
And so it's because that that stem becomes rotted or
overall weakened that it startsto fall over, starts to lodge
and might also bring some of thesurrounding plants down with it
as well, right?
SPEAKER_02 (04:49):
Yeah.
And it has a characteristiclook.
So, you know, a lot of times, alot of years we see a lot of
rice lodging and that's kind ofnormal, you know.
This year seems like we're nothaving, it's not going to be a
lodged year.
Like there's not a lot of ricedown.
I'm sure there'll be some.
But when it's caused by stemrot, it doesn't look flat.
(05:12):
So when the rice lodges,typically at the point where
it's rotted, the tiller, becauseof the stem rot, that's where it
will kind of bend.
And so it gives it a more, not auniform, but there's a pattern
to it.
So you see these ups and downson the field.
Some of the stems are kind ofup, but then the rest of the is
(05:35):
down.
And so that can be a pointer tothat what's causing it is not
just regular lodging, but causedby stem rot.
SPEAKER_01 (05:45):
Yeah.
I mean, we know stem rot'sincredibly common.
You see it in almost every ricefield.
But is there a reason why it'sso widespread?
I mean, how does the diseasespread once it's established?
SPEAKER_02 (05:59):
Well, that's a good question.
So typically, yes, we see stemrot in every field.
So the level of stem rot varies,but all fields have stem rot.
So it's pretty widelydistributed.
Now, I think over the years, thedisease can get worse because
what happens is the pathogen,when it grows inside in the
(06:22):
tiller and towards the end ofthe season, actually right now,
you know, if you pick up a fewtillers that have stem rot and
you peel them, you will seethese, they look like grains of
sand but they're black.
And those are the restingstructures of the pathogen.
Those are called the sclerotia.
And so these sclerotia are ableto survive in the residue and in
(06:48):
the soil as well.
And then as they accumulate,then the disease becomes more
severe.
And there's research from backin the, I believe it was maybe
the late 80s, where they did thework where they recovered the
sclerotia from the soil and thenrelated that to the level of
severity of disease in thefield.
(07:09):
And as you had more sclerotia,the disease was more severe.
And so over the years...
And this might be related to,you know, when we stopped
burning, this disease started tobecome more apparent.
Over the years, those sclerotia,you know, you accumulate them
(07:29):
and you get more and more ifyou're not doing anything to
avoid that development, right?
And so that's how you get tosome fields where you have high
levels of stem rot.
SPEAKER_01 (07:41):
So you're not doing anything to manage that residue
in a way that completelydeclines or removes it from the
field, the sclerotia are hardyenough to survive the winter,
reproduce, and potentially causemore of an infestation of stem
rot in the next year.
SPEAKER_02 (07:58):
Yeah, so those sclerotia, Bob Webster, who was
the pathologist, you know, backin the day, they determined that
sclerotia half-life is almosttwo years.
Wow.
So they can survive quite a bitof time in the soil.
And like I said, as theyaccumulate, then the disease is
(08:20):
worse and worse.
And so, you know, there was astudy they did where they would
have fields where they didn't doany straw management versus
fields where the straw wasincorporated and then the field
was winter flooded and otherfields.
Well, and then, yeah, and thenburning and other fields were
burned.
(08:41):
And so where you had the leastaccumulation of sclerotia was
where you were burning.
burning because you were gettingrid of all the residue,
including the sclerotium.
Then on the winter flooded, youknow, with the residue
incorporated, that was kind ofmedium.
And then where you had the mostaccumulation was in fields where
(09:02):
nothing was done.
The straw was left on thesurface and then just worked in
in the spring.
So that's where you had themost.
So, you know, and depending onthe winter, the, you know, the
degree of Decomp that you getvaries, and so the better decomp
you get, it helps reduce theamount of sclerotia.
(09:23):
And the other thing also, so thesclerotia survives in the straw.
It can also survive in the soil,but the sclerotia is going to be
in the straw.
And once we get into those maybelate February, early March days,
(09:43):
and it starts warming up, alittle bit, those sclerotia can
germinate and they feed on thatstraw and then produce more
sclerotia.
And so that's why it's soimportant to try to get rid of
that residue because then youdon't get that, you know,
increase that can happen duringthis, you know, late winter,
(10:04):
early spring.
SPEAKER_01 (10:05):
Okay.
Yeah.
So, I mean, it sounds likeburning used to be one of the
best ways for us to reduce theamount of...
inoculum in the soil.
Obviously, we've talked aboutthis before, you and I, earning
at least in large scale acreageis no longer that viable of an
option, at least in the vastmajority of the rice acreage.
(10:27):
I think CARB only allows about20% of the rice acreage.
And then there's a certainamount of acreage each county
gets.
And so it's definitelyeliminated.
Growers have had to look intodifferent methods of decomp in
order to remove their straw andtry to account for any disease
management
SPEAKER_02 (10:44):
Yeah.
And I think, you know, burning,I mean, we always knew that
burning was a positive in termsof disease management because,
you know, we were getting rid ofall that sclerotia.
And there's also aggregateshe-spot, which is another very
similar disease that also, youknow, survives via sclerotia in
the soil.
(11:06):
And then blast and to a pointback.
So, yeah, we always knew thatburning was good for disease
management.
But since we lost that, I thinkwe've seen disease management
become more important.
And maybe the impact of some ofthese diseases that in the past
(11:27):
were not that impactful, youknow, we're seeing them become a
little bit more concerning.
And so, yeah, the managementstrategy still is to try to do
the best you can when it comesabout managing straw and
(11:49):
decomposing straw, getting ridof that straw.
Now, you know, I don't thinkthere were any studies looking
at baling.
But baling can be very variable.
It depends on what height you'recutting that straw.
And even when you bale, you'recutting as low as you can,
there's going to be a lot ofresidue left in the field.
(12:10):
Theoretically, removing residuewith sclerotia would be
positive, but to what degree, Idon't know.
It's going to depend on how lowyou can go with the baling, how
low you can cut.
SPEAKER_01 (12:25):
And then what you do with your stubble as well.
And then that's just anotherpass to get in before winter.
So a lot to worry about.
SPEAKER_02 (12:32):
Right.
Maybe if you burn that stubble,that might work out to be as
effective as a burn, you know, aregular burn.
SPEAKER_01 (12:41):
And if you can't get in burning, maybe you stomp it,
I guess, if you can.
SPEAKER_02 (12:46):
Yeah.
But I don't know to what degree,you know, growers that are
baling, are they still, youknow, too concerned about trying
to get that stubble incorporatedWe've
SPEAKER_01 (12:59):
talked a bit about some of the management options
that are available.
And first and foremost, ofcourse, is just straw and straw
decomp.
But there's also a factor thatfertility can play, at least
when it comes to the incidenceof stem rot.
And I understand from some ofthe work that you and Bruce have
done is that excess nitrogen canactually increase the severity
(13:21):
of stem rot.
Would you care to touch on thata little bit?
SPEAKER_02 (13:24):
Yeah.
So, and yeah, and then again,we've talked a lot about the
importance of We've also knownthis from back from Webster's
days.
Yes, excess nitrogen.
So if you have high levels ofnitrogen, you will have higher
stem rot.
And you typically see it justlike with blast.
You see it on the headlandswhere there's overlaps.
(13:45):
That's where you would typicallysee more stem rot because you
have more nitrogen.
But the other nutrient that'simportant is potassium.
And I, you know, every time I...
I talk to growers and PCAs aboutstem rot.
I always tell this story where,you know, I was working with a
grower that had a really severestem rot field.
(14:09):
And, you know, yield was in the70s or so.
And, you know, we did trials fora couple of years, you know, try
different fungicides, differenttimings, and nothing seemed to
make a difference.
And then one year they realizedthey were low on potassium.
And so, and I didn't think ofthat, but they, you know,
(14:34):
addressed that issue andincreased their potassium
fertility to a level that, youknow, was recommended.
And then the stem rot kind ofwent away.
It didn't go away completely,but their yields went up, you
know, back to the 90s or so.
So, yeah, potassium is, it's areally important nutrient when
(14:54):
it comes to And does it matter?
I
SPEAKER_01 (15:13):
know in some of the work you've put out, you've
noted specifically that surfacesupply potassium fertilizer is
reported to reduce race stem rotdevelopment.
Is there any other types of stemrot?
of application of potassiumfertilizer that you've looked
at?
SPEAKER_02 (15:29):
Oh, I see.
Like thinking about maybe foliarfertilizers?
SPEAKER_01 (15:33):
Yeah.
Has there been anything you'velooked at with that?
SPEAKER_02 (15:37):
You know, no, we haven't.
I don't think there's any datashowing, I mean, any other type
of fertility that would, eitherway, like that works or not.
Yeah, the work that was doneearlier was looking at, well, I
would have to look at what theyused, but it was just, yeah, dry
(15:58):
fertilizer, you know.
What we don't know is, sousually we put the potassium
with the phosphorus either as a,you know, early before when
we're doing field work or youput it later, you know, about 20
days after planting because justto avoid the scum with the
(16:18):
phosphorus if, you know, mostlikely putting phosphorus as
well.
What we don't know if later alight potassium would be as
effective.
And that's out there and thatmight be something that might be
worth, you know, researching alittle bit because some cases
you don't realize that you havea deficiency or, you know, a
(16:41):
potassium or a stem rot issueuntil late in the season.
And so at that point, you know,would it be worth putting some
potassium in, you know, wouldthat correct some of the
deficiency?
We don't have, we don't know.
SPEAKER_01 (16:56):
And then another, I guess, cultural manage option
when it comes to stem rot isalso your varietal choices.
And I know that I think I'veread that the shorter season
varieties, your M105, your S102,Kalmochi 101, I think it is,
they might be more susceptibleto stem rot and the other
(17:18):
diseases rather than maybemid-season.
So 209, 210.
Is there a reason for that,Louise?
SPEAKER_02 (17:26):
Yeah, so I think it's just, we have with later
season varieties like N211, youhave a thicker, more
structurally strong tiller, sayan M105.
And yeah, we've seen that intrials.
We did that three years oftrials comparing varieties.
(17:50):
And we did see that thesevarieties with thicker tillers
had developed less stem rot.
They still developed it, but theseverity to which they developed
it was less than the thinnertiller varieties.
And also something to keep inmind is all the varieties have
(18:11):
different responses.
And so the varieties from therice experimentation when they
put them out they do have a stemrot score so one could compare
those scores you know or I don'tthink growers are going to
choose a variety based on thatbut you know you can see what
the score is to have an ideacompared to say an M206 or an
(18:34):
M210 but yeah I think in generalvarieties that have thicker
bigger stems or tillers tend todevelop less severe stem.
SPEAKER_01 (18:45):
I have heard that about 211, that it leaves a lot
of straw behind and it's gotreally thick stems.
So that makes sense.
It's possibly more structurallysound, more able to resist.
SPEAKER_02 (18:57):
Yeah, somehow, you know, we thought about it.
What could it be?
But I, you know, I don't have agood answer because the tiller
is...
There's nothing inside thetiller.
The tiller is just a structure,and then inside the tiller
there's nothing.
So it's not like the tiller isthicker.
They're all about the samethickness, but maybe just the
(19:23):
tiller being bigger allows theplant to be able to withstand
that stem rot better.
There's still some tissue bywhich the plant can move
nutrients up to fill thosekernels.
But anyway, but yeah, wemeasured tillers and we did find
that thinner meant higherseverity.
SPEAKER_01 (19:44):
So, I mean, there aren't a ton of options when it
comes to chemical control ofthese diseases.
In fact, I remember a talk yougave, I think last year, when
you were talking about fungicidetreatments and then your next
slide was just saying like, andbasically we've got quadris.
Because in California rice, it'spretty much is and occasionally
(20:08):
propiconazole, right?
SPEAKER_02 (20:11):
Yeah, and I don't think propiconazole has much of
an effect on stem rot.
But yeah, it's one activeingredient we have,
azoxystrobin.
And we've done quite a fewtrials over the years, and we do
see a reduction in severity.
It's not huge.
(20:33):
It's maybe a 20-30% reduction.
Especially when stem rotseverity is moderate to maybe
high.
But if it's very high, then it'svery difficult to control it, to
reduce that severity.
But anyway, yeah, withazoxystrobin, we can reduce the
(20:54):
severity when we apply thefungicide at the early heading
stage.
So sometime in between the, youknow, when you got that boot
split and the first few paniclesare visible above the canopy,
you know, that's about the timewhen, if you do an application,
(21:16):
you'll have a reduction inseverity.
For many years, you know, wethought that putting the
fungicide early, like maybe withPropanil, at Propanil time,
would be more effective.
Because at that time, you know,you don't have a canopy that's
as thick as later.
(21:36):
And so you can actually get thefungicide down at the water
level.
But all the trials we've done,rarely do we see a benefit when
we put it at that time.
So...
It could be that it's a littlebit too early.
Reviewing the information that'sout there, the stem rot seems to
(22:01):
be or infects the plant at aboutPI.
So, you know, propanil time is alittle earlier than that.
So maybe it's a little too earlyand there's not enough residual
effect to protect.
But the fact is, yes, we don'tsee much benefit early.
The benefit is at heading, earlyheading.
(22:21):
Which I think works well becausethat's also the blast timing,
you know, in case blast was aproblem.
SPEAKER_01 (22:30):
Two birds, one stone.
You're doing, taking care ofyour diseases at the same time.
SPEAKER_02 (22:34):
Yes.
Right.
SPEAKER_01 (22:35):
Or trying to, anyway.
SPEAKER_02 (22:36):
Yeah.
With, yeah, the other disease,you know, that's, like I said,
is similar, is aggregate sheath.
But that one, yes, you know, ifyou apply early, you're at
propanil time, the esoxystrobin,we do see a benefit there.
Aggregate she spot is mucheasier to control than stem rot,
(22:57):
I think.
We see a much higher efficacy ofthe fungicide when trying to
reduce aggregate she spotlevels.
And, you know, in general, wedon't have a lot of very severe
aggregate she spot, you know.
So the levels of disease thatare out there, it's not very
high.
(23:17):
So maybe that's why we see, youknow, more efficacy.
But yeah, it's a little easierto control.
to manage that.
But yeah, so yeah, that's thetiming for stem rot is early
hitting.
SPEAKER_01 (23:28):
And then when it comes to monitoring in your
fields and then figuring outwhen to treat, if you need to
treat at all, what does it meanwhen we say like, when do you
monitor for stem rot?
What does that look like?
And then do we have treatmentthresholds for this disease?
SPEAKER_02 (23:50):
Yeah, so the monitoring, you know, I've been
working on that for a few yearsnow.
And so typically the way wedetermine the severity level of
a field is we take samples atdrain time.
You know, we cut tillers, thenrate them, and then we know the
severity.
Now, you know, growers, PCAs,they're not going to do that
(24:12):
because it takes a lot of time.
And, you know, at that time, allyou get is information maybe for
next year.
Yes, there's a lot of stem rotin this field, you might want to
do a better job of strawmanagement or incorporate a
fungicide in your program orconsider that stem rot might be
(24:34):
an issue.
So what I've been doing istrying to relate stem rot
incidents early at about theboot stage, so before a
treatment would be done, withour ratings at drain time.
(24:55):
And there seems to be arelationship.
We're still doing it this year,so this might be the last year
we've done it.
But what we have done so far,I've seen that if you get about
half of your tillers with stemrot lesions at the boot stage,
then that's going to mean you'regoing to have a lot of, well,
(25:20):
100% of tillers with stem rot atdrain time.
So that would be a way to kindof monitor for stem rot, is you
can go at the boot stage, lookat your tillers, and if you're
seeing, 50% of them with stemrot, then you might want to
(25:41):
think, okay, maybe you need todo something.
And so we'll, you know, we'restill refining this.
Like I said, we're doing anotheryear of trials.
And hopefully, you know, nextyear or in a couple of years,
we'll have something more solid.
But that's what I've beensharing with the PCAs and
(26:04):
growers right now.
So about 50% at boot time.
Or if you're just looking atdrain time, you know, just kind
of checking things and seeing,you know, what the crop's going
to be like.
If all your tillers have stemrot lesions, you're probably at
a higher, at a high severity ofstem rot.
(26:28):
And so you might want toconsider, you know, trying to
burn or, you know, trying toreally up your straw management.
SPEAKER_01 (26:37):
And when you say that the tillers have lesions,
is there a certain severity ofthose lesions or severity of the
disease incidence that has anyrelation to that?
SPEAKER_02 (26:48):
No, just if you can just see the lesion, that, yeah,
that means that the disease isthere.
Yeah.
SPEAKER_01 (26:55):
So, Luis, when you say that we're doing ratings at
drain time for tillers, let'stalk about what that looks like.
What does it mean when we takethe crew out there and take a
bunch of tillers and then how dowe figure out how much stem rots
out there?
SPEAKER_02 (27:10):
Yeah.
Yeah.
And again, we do this forresearch purposes.
So this is not something that,you know, we would expect
growers or PCAs to do.
But so what we do is, you know,we have our plots and we go into
our plots.
We take three handful of tillersfrom different areas and then we
just randomly select 50 tillers.
(27:31):
And then each of these tillers,we start peeling them and
looking for stem rot lesions.
And so if we only find stem roton the outer leaf sheaths at the
water level, then we considerthat, we give that a rating of
one.
If we peel that and we see onthe next layer, the next leaf
(27:51):
sheath, you know, there's alesion there, then that would be
a level two.
And you continue peeling untilyou get to the, usually after
that you get to the main column,the main tiller.
And so once you get to the maincolumn, if you see a lesion on
that, then that's a level three.
(28:11):
And then if that column isrotted, so it's black all around
and you open it up and you cansee actually the white mycelia
growing inside, then we considerthat a level four.
And obviously if the tiller'shealthy, which we also find
(28:34):
healthy tillers those would bezeros and so that's how we rate
and so we rate then we count howmany tillers for each each level
and then we calculate like aweighted average sort of and
that gives us our severity indexand what we found is when we are
(28:55):
at a level two or more that'swhen you see very high numbers
of tillers will show lesions soso the incidence is very high
but you cannot differentiatejust looking at incidence or so
(29:16):
the number of tillers you knowthat are infected you cannot
differentiate between a two anda three just two and high two
and above it's always 100incidence so that's why we say
you know if you're 100 you'reprobably severity two or above
so it can be very severe Butlike I said, that's, you know,
we do that for research.
(29:37):
Now, you know, sometimes when wego out to the field, you know,
we show a grower, a PCA, what itlooks like.
You know, you can peel thoseleaf sheaths and then look at
the comb, and if it looks niceand clean, well, you can feel,
you know, comfortable that,yeah, the stem rot is not very
severe.
But if you start finding a lotof tillers with lesions in that
(29:58):
main comb, then that means that,yeah, there's, you know, that is
a severe stem Yeah.
SPEAKER_01 (30:05):
Thanks for explaining that, Luis.
So Luis, obviously you get a lotof like disease calls and
especially at this time of year,do you have, I guess, an
estimation or just a guess on ifthis is a high disease year or
if this is just kind of a lowlevel disease year across the
region?
SPEAKER_02 (30:24):
Well, I see.
In general, not just Tembra.
So You know, real quick,bacchani is still around.
Nothing that would, I think,affect yields, but still
something that's an eyesoreearly on.
You know, you see all theseplants that are, you know,
obviously affected by bacchaniand, you know, it can be a
(30:46):
concern.
But like I said, nothing thatwould cause a yield reduction.
Aggregate sheath spot istypically not a very important
disease.
So we see it every now and then,but I've never seen it very
severe as to be of concern.
Stem rot, you know, the fieldsthat have it, they will continue
(31:07):
to have it.
And fields that do not have it,they might increase or decrease.
You know, how severe stem rot iskind of tends to be, you know,
pretty stable.
Now, the other disease thatvaries quite a bit is blast.
And there's been some blast thisyear.
Most of the fields I've seenhave been in the northwest side
(31:31):
of the valley, so Glen Countynear Willows.
Some fields have been severelyaffected.
I think they're going to have ayield loss.
Other fields, there's justspots, you know, the nitrogen
overlaps.
That's where you see it.
There was some leaf blast earlyon.
(31:53):
I did not see it until later,until, you know, just last week
where I was looking at somefields.
But there was a little bit ofleaf blast.
And so...
We'll see in these fields ifthey actually see much of a big
yield loss, but some fields, thedisease came late, and so the
panicles were already, you know,filled.
(32:15):
So hopefully those are not goingto be too affected.
So overall, you know, up inWillow's area, yeah, blast was
present.
Everywhere else, I reallyhaven't seen much, any blast.
And SMOD, I have seen verylittle SMOD.
Very, very little.
(32:36):
So, yeah, best way to avoid SMODis let me put a trial in your
field.
So anyway, yeah, I think thoseare our main diseases.
SPEAKER_01 (32:50):
Yeah, we're pretty fortunate.
I mean, knock on wood, here inCalifornia, we don't have the
disease pressure that otherareas do and grateful for it.
But it always makes us a littlenervous, I think, if we do start
to see a bit of creep up anddisease like we did a couple of
years ago with that blastinfestation.
SPEAKER_02 (33:10):
Yeah, yeah, we're lucky.
So this is unrelated, but so inthe southern U.S., you know,
Louisiana, Texas, Arkansas, nowthey're finding this, the risal
facet, which transmits the...
And so now they have a newdisease they have to worry
about.
(33:31):
And, you know, hopefully wewon't have to worry about that.
But it's good to keep an eye outfor this bug.
SPEAKER_01 (33:39):
Luis, is there anything else you want to share?
Any upcoming events orinformation you want to share
with the crowd here?
SPEAKER_02 (33:47):
So, yeah, I was thinking that with this year,
you know, I had one experimentwhere I was looking at the
effects of COVID-19.
of top dress on Stambra.
And so, you know, some of thework that Bruce has done has
shown that it's better to putall your nitrogen up front as
aqua.
(34:08):
And if you don't need a topdress, then, you know, don't put
it.
If you typically put a topdress, instead of putting those
30 pounds of nitrogen, you know,at that time, just add your
aqua.
Increase your aqua by 30 unitsand don't top dress.
And some people have adoptedthat.
(34:28):
But I was wondering, well, doesthe top dress have any effect on
stem rot?
You know, because we're puttingthe nitrogen right about the
time when stem rot becomes to bea problem.
And so, yeah, I had a smalltrial, you know, at the station
in Biggs.
And I've looked at some of thedata.
(34:48):
And, you know, it's notsignificant, but in all the
plots where we put a top dress,the stem rot was slightly
higher.
And in plots where we didn't puta top dress, we just put all the
nitrogen initially as aqua.
So, you know, it was just a kindof, let's see what happens.
(35:09):
I think I'm going to do it againnext year.
Any
SPEAKER_01 (35:12):
events or anything, Luis, or any resources you want
to point people towards?
SPEAKER_02 (35:17):
Oh, well, so we have our fact sheets, you know, and
there's a fact sheet on tillerdiseases, so stem rot and
aggregate sheet spot.
There's a fact sheet on onpotassium as well.
And I've been directing growers'PCAs to those when we get calls
about disease management.
(35:38):
Yeah, and events, I don't thinkthat we have anything coming up
until our winter growermeetings, yeah.
SPEAKER_01 (35:48):
Okay, Luis.
Well, thank you so much formaking the time.
SPEAKER_02 (35:51):
All right.
Yeah, no problem.
This was fun.
SPEAKER_01 (36:16):
Now, we don't have any upcoming rice events, but
there is an upcoming event withthe UC Master Gardener program
based out of the Colusa office.
The Colusa UC Master Gardenerswill be hosting a pumpkin
centerpiece workshop just intime for the fall season on
Thursday, October 16th from 6 to8 p.m.
(36:38):
in the Colusa IndustrialProperties Conference Room.
Registration is required forthis event.
You can visit our office or callin to save your spots and you
better save your spot prettyquick because the spots for this
workshop go pretty quickly ifyou have any questions please
reach out the number is530-458-0570 there is a cost
(37:05):
associated with this workshop itis$30 per person and that
includes all supplies needed totake your lovely pumpkin
centerpiece home with you justin time for the fall season
We've also been asked to make anannouncement on behalf of the
Western Region Certified CropAdvisor Program, also known as
(37:26):
WRCCA.
They reached out to us to ask usto help celebrate some
accomplished individuals thatthey honored at the WRCCA annual
meeting this past week inVisalia, California.
The WRCCA program is committedto refining the knowledge and
skill of those making decisionsin the CCAs play a vital role
(37:49):
working with producers to ensuresustainability and long-term
success.
For more information, visitwrcca.org.
WRCCA announces the 2025 CCA ofthe Year and Alan Remander
Scholarship and Mentor Awardprogram winners.
The Award for Certified CropAdvisor of the Year in the
(38:11):
Western Region acknowledges themembers' exemplary dedication
and contributions to agricultureand WRCCA is excited to announce
the 2025 CCA of the Yearrecipient is Eric Pooler.
Eric's career has focusedspecifically on wine grape
production, spanning time withmany of the most distinguished
(38:31):
wineries and farming operationswithin the U.S.
wine industry.
Congratulations, Eric.
The Alan Romander Scholarshipand Mentor Awards Program honors
the life work of dedicatedagriculturalist and leader, Alan
Romander.
1941 to 2019.
Alan Romander was one of thefirst CCAs in California, and
(38:53):
his passion for agriculturecreated a lasting impact on
those around him.
We would like to congratulatethe following individuals for
receiving a scholarship.
In the South Valley, werecognize Carlos Vega Lara,
hailing from Parlier,California, and attending
Reedley Community College andmajoring in plant science.
Next year, he plans to transferto Fresno State to earn a
(39:15):
bachelor's in plant science witha minor in agronomy, while
gaining experience to take tothe certified crop advisor
exams.
In the North Valley, werecognize Reed Scott from Yuba
City, California, currentlypursuing a major in integrated
plant sciences at WashingtonState University.
His goals include obtaining aCCA, PCA, and QAL to further his
(39:38):
value in education in theindustry.
In the desert region, werecognize Joseph Clark from
Yuma, Arizona, presentlyenrolled at University of
Arizona with a major inagricultural systems management.
She plans to become a CCA as shegraduates in 2026.
In the coastal region, werecognize Roberto Lopez from
(39:59):
Oakdale, California, currentlypursuing a degree in
agricultural science with aminor in plant protection at
California Polytechnic StateUniversity San Luis Obispo.
Looking ahead, he plans tocontinue combining hands-on
farming experience withagribusiness insights to support
innovations sustainability, andworkforce development across
California agriculture.
(40:21):
We congratulate all thesescholarship winners for their
achievements.
Mentor awards are granted toexceptional professors who teach
agronomy-related coursework.
Our mentor award recipient isDelia Melendez, adjunct
professor of plant science atLos Angeles Pierce College.
Delia is a student of PierceCollege herself and has
(40:41):
associate degrees in bothhorticulture and landscape
design, and a bachelor's degreein horticulture from Oregon
State University, and abachelor's degree in
horticulture from Oregon StateUniversity.
Oregon State University.
With the honorarium grantfunding, the students will
benefit by applying it to twostudent projects at Pierce
College.
Both projects provide thestudents with opportunities to
(41:03):
experience hands-on learning andto gain knowledge about various
aspects of agronomy as appliedto a practical situation.
We congratulate the Mentor Awardrecipient, Delia Melendez.
WRCCA is proud to announce therecipient of the 2025
Distinguished Service Award Thisaward acknowledges a retired
(41:24):
certified crop advisor, CCA, whohas dedicated their career and
volunteer time to the CCAprogram in agriculture industry.
WRCCA is excited to announce the2025 Distinguished Service Award
recipient is Fred Strauss.
Fred Strauss began his career asa pest control advisor and was
(41:44):
an active member of theCalifornia Association of Pest
Control Advisors, or CAPCA.
He was recognized as a CAPCAmember of the year in 1991 for
the time and effort hegenerously gave to the
organization.
When the Certified Crop Advisororganization was established in
1992, he was among the first toget certified.
He was later asked to serve onthe CCA board, holding various
(42:06):
positions including chairman.
For many years, Straussspearheaded the marketing
efforts of the Western RegionCCA program, manning booths and
prioritizing the growth of theorganization.
He eventually began working withWestern Farm Service, which is
now known as Nutrien.
After retiring, he remainedengaged in the industry,
(42:27):
volunteering with theInternational Certified Crop
Advisor Board.
Advisor Strauss is well known inthe industry for his kind
demeanor, passion for the CCAprogram, and the ability to have
an engaging conversation witheach person he interacts with.
Congratulations to Fred Strauss.
(42:48):
Remember, Like the growers liketo say, have a rice life.
(43:16):
The material and informationpresented here is for general
purposes only.
The University of Californianame and all forms and
abbreviations are the propertyof its owner and its use does
not imply endorsement of oropposition to any specific
organization, product, orservice.
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