Rice blast basics with Luis Espino

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Together, the UCCE Farm Advisors seek to provide relevant, topical research-backed information relating to CA rice production.

Today Luis Espino and Sarah Marsh talk about rice blast in California, weather conditions that favor disease development, and future research plans.

Rice Blast Resources

UC IPM - Rice Blast

Leaf Wetness Blast Correlation Charts

Other Resources

UC Rice Blog

UC Agronomy - Rice

Rice Briefs (Colusa/Yolo)

Rice Notes (Yuba-Sutter)

Rice Leaf (Butte/Glenn)

Rice in the Delta


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.

The views, thoughts, and opinions expressed are the speaker's own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Transcript

SPEAKER_02: 0:00

Hello and welcome to Thoughts on Rice, a podcast hosted by the University of California Cooperative Extension Rice Advisors. I'm one of your hosts, Sarah Marsh, and I'm a rice farm advisor for Colusa and Yolo Counties. I'm Whitney from The Forest. I'm the Cooperative Extension Rice Advisor for Sutter, Yuba,

SPEAKER_00: 0:34

Placer, and Sacramento counties. My name is Luis Espino. I'm the Rice Farming Systems Advisor for Butte and

SPEAKER_01: 0:44

Glynn counties. I'm Michelle Leinfelder-Miles. I'm a farm advisor in the Delta region. I work on all sorts of field crops, grains and forages, but one of those is rice. And the counties that I cover are San Joaquin, Sacramento, Yolo-Solano, and Contra Costa counties.

SPEAKER_02: 1:03

Together, the UCCE Rice Farm Advisors seek to provide relevant, topical, research-backed information relating to California rice production. Today we'll be expanding on our mini episode about Blast, which was released a few weeks earlier. We're going to delve a little bit further into the history of Rice Blast in California, as well as touch on some upcoming and planned research efforts hosted by our very own Luis Espino. Stay tuned for more. Music Rice Blast has been in California since the 90s. Was it spotted in California before that and then it went away? Or was that basically the first time it was found?

SPEAKER_00: 1:57

No, that was the first time. So yeah, we didn't really have it until the late 90s. And that's when it was found initially in Colusa and Glynn Counties. Always Glynn County for some reason. That's where everything, you know, mimic, what they call mimic, you know, it started in Glynn County. Blast, I think it's Glynn County too.

SPEAKER_02: 2:18

That is fascinating. I mean, for those people who don't know it's a small county up in northern california and yet here it is the epicenter of most of our rice problems

SPEAKER_00: 2:27

not to blame them but it just happens

SPEAKER_02: 2:30

not at all no and so blast i mean we said that rice blast you see it throughout the season it has different formulations leaf blast neck blast but on the whole of over the course of a season how damaging is blast and what are the effects on yield

SPEAKER_00: 2:47

so the effects on yield when you get neck blast can be very uh very severe. So you can have huge losses. I mean, easily, you know, 20, 30%. I would say even 50% in bad situations. So it can really hurt the timing for monitoring. You know, you start early on the vegetative stage, checking if you see any blast, you know, you know, you're going to have to protect the crop later on. But the issue with diseases is that a see, you know, it's not like with insects where you can see the insects and then when they get to a certain number, you can do a treatment. With these diseases, you don't really see the pathogen until you see the symptoms. And so with blast, it's kind of like that, that even though you might not see any leaf blast, you can still get neck blast. You know, one way to kind of monitor is to be aware if blast is in the area. So, you know, what are you hearing from your PCA, from the neighbors you know are they are they hearing that yeah there's blasting in the county And if so, then a treatment, a protective treatment might be a good idea.

SPEAKER_02: 4:03

And what kind of treatments are available for Blast? It's azoxistrobin. There's a lot of different formulations, but that's pretty much it, right?

SPEAKER_00: 4:12

There's different commercial names, you know, generic products. You know, the commercial name that everybody knows is Quadris, but there are several other generic products. And yeah, the active ingredient is azoxistrobin. And that's pretty much the only fungicide that we know is has efficacy against blast. And we've done trials. Yeah, we see good, good reduction in neck blast incidents when we do treatments with Asoxystrobin. And the treatment needs to be timed right. So you need to go at very early heading, even at the late boot stage. So because what you're trying to do is protect the panicles. So as the panicles emerge, you want to have those panicles protected. And that timing is when we see the best protection.

SPEAKER_02: 4:59

Is there any post-harvest management practice that can help with blast or prevent it or reduce the amount of inoculum?

SPEAKER_00: 5:07

So with blast, the inoculum can stay in the field. It can be in the crop residue. It can be in kernels that end up growing back in the field. And so anything that decomposes the straw, so burning also would work, would help in reducing the amount of inoculum in the field. So certainly in managing the crop residue plays an important role. But during the season too, so during the season, you know, you want to avoid excess nitrogen. So you've got to be careful with the nitrogen. Have the right variety. And like I said, if there's blast in the area, blast either in vegetative stage or, you know, if the neighbors, you know, in the area, there's some blast infections, then a preventive treatment might be a good idea. Something that we had for a little bit, and I didn't see it, was a warning system for blast. When we had weather conditions that were good for blast, there was a system that would alert growers that, yeah, we were having conditions that were good. And that's something that I'm looking into again. I've been consulting with Chris Greer, trying to get some of his ideas, because he did a little bit of that work, because I think it would be a technology. Right now I have three weather stations in three fields in Glynn County with a history of blast. And so I'm collecting that data and I can collect it real time. So, you know, I get it every day. I can download it on my computer, analyze the data, and I can know if we have conditions for blast or not. And so I think if we can develop something that we can use where we can monitor through the season and then when we start seeing conditions that are good for blast, we can let everybody know that might help with preventive treatments, especially if we're seeing blast like, you know, we're already seeing it this year starting. So, and yeah, that's what I've been seeing on my weather monitoring. It's like, yeah, we're seeing conditions that would be conducive for blast.

SPEAKER_02: 7:15

And just to say that again, the conditions that favor blast development, that's higher humidity, right?

SPEAKER_00: 7:21

For the infection, yeah, you need high humidity, which means that there's going to be free moisture on the leaf what they call leaf wetness that's key so you need that dew on the surface of the leaf to stay there for long periods of time now temperature plays a role and relative humidity plays a role on sporulation and how quick these spores germinate and infect but if you don't have that leaf wetness infections cannot happen so that's why in other parts of the world where they get rain during the season so they they get those extended periods of time periods of leaf wetness, the blast is much more severe. We don't have that. But we do have conditions that allow for blasts. So I'm monitoring that. I'm trying to track the hours of leaf wetness that we get versus the hours of leaf wetness that are needed for infection and see where those two meet. And that would be when the blast conditions are good for infection.

SPEAKER_02: 8:23

I think you've put a couple of those charts with the monitoring of the leaf wetness correlated with the line that's needed for blast development on the rice blog as well so people can go look at that if they're interested in seeing how that's been progressing over the season

SPEAKER_00: 8:38

yeah and this is just a kind of a first attempt right hopefully we'll we'll work on on that more next year and i think we're seeing that it tracks in because we see that yeah we had the good conditions about a week ago and now now we're seeing the blast show up but there seems to be a relationship there but the other thing that would be missing on this forecast system or warning would be the actual presence of the pathogen in the air so the spores so if you think back you know your plant pathology classes you know they always talk about the disease triangle so you need yeah you need the environmental conditions you need the susceptible host and then you need the pathogen has to be present that's a little bit more challenging to collect spores from the air. It's not impossible, but it's done in other systems for other diseases. But the amount of technical expertise needed, you know, it's higher. But we'll look into it. I know there's other states are interested in having something like that as well. So maybe something will come out in the next few years. Something that I've been wanting to do for quite a while is this thing called pathotyping, the BLAST. So BLAST is has these different races. They can be in other plants, but even the blast that infects just rice, there's different races. And the genes that give resistance to the varieties are race specific. So if you have a race for which you don't have a gene of resistance, then that plant is going to be susceptible. So when blast was first found in California in the late 90s, There was work done that determined that we had one race, because you can have many, a lot of races in one environment. So we only have one race, which is the IG1 race. And then at the time, then they developed a resistant variety, M208, which had a gene for resistance for this race. And so M208 was used for a few years, but after a few years, we started seeing some little on M208. So there's several possibilities. One is that there might be a new race that was introduced at that time, and then that race was able to infect M208 because the gene in the variety didn't give resistance to this new race. That might not be the case. Actually, some of the studies that have been done more tend to, they kind of indicate that what we have is maybe a mutant of our race. It just changed enough so that it was able to infect M208. Because the infections on M208 at the time, they were not, you know, they were very small. It didn't develop explosively like it usually does when you have a susceptible variety. But anyway, I'm not a pathologist, so I can't expand too much further than that. But, so that brought up the question is, you know, since the late 90s, now we're in 2024, you know, there's been quite a few years where we haven't looked at the races. What races do we have in California? And without knowing the races, the blast races, the breeders can't put the right genes on the varieties. So right now we have our resistant variety M210, and it looks like the breeders, the gene that they put in there is a good one, or is the right one, because we're seen resistance to the blast that we have in the field. But that's a question that the breeders have is, do we have any other races? We need to worry about, we need to start putting other genes that will give us protection against those other races. So yeah, for that, what we need to do is collect infected tissue and then isolate the fungus out of that tissue and then do the tests to be able to tell which races we have. So we need a sample of blast infected tissue from different areas in California for, you know, we can take those samples for three years or so and use that to see if we can determine what are the races present in California. If we still have that one single race, that's great. But if there is another race, then the breeders can start working on adding a gene that gives resistance to the races that we have.

SPEAKER_02: 13:24

Let me ask you, Luis, how long has M210 been commercially available?

SPEAKER_00: 13:29

It's been out for quite a few years. It was really 2019. Yeah, but we haven't had a lot of blast. I mean, really the first year where we've seen M210 being put to the test was 2023. Because

SPEAKER_02: 13:43

I'm just wondering like if it's been out for a number of years and we haven't yet seen much infestation of blast on this resistant variety, that kind of helps add to the idea that maybe there's just one race out there. Well, that would be interesting. So a three-year study collecting the fungus from all over the rice-growing regions, probably on different varieties that we see them on, and then isolating them, boiling them down to their genetic differences, and then just trying to typify, see if there are different races.

SPEAKER_00: 14:16

Yes. And so that's something that we need to do. And, you know, probably we will work together with a plant pathologist that can do that type of work. I don't think right now we can have we don't have anybody in california that that would do it but there's somebody working with the usda in arkansas that has you know has told us that he's willing to to do that work with us

SPEAKER_02: 14:40

that'd be really interesting to see yeah

SPEAKER_00: 14:42

so i'm hoping that maybe if we see quite a bit of last this year maybe uh you know we we collect some more and maybe next year we can send samples to be analyzed so what i what we did last year was collected a many panicles as we could from infected fields. Then we brought them to the lab. We let them dry out, air dry. And then we just clip the necks where the lesions were. We put them in small vials with a little bit of material that keeps them dry. And we have them in the freezer. So that should work. That's what I've been told. So

SPEAKER_02: 15:17

that's, I guess, future research plans. What current research with LAST are you undertaking this season?

SPEAKER_00: 15:24

Well, we have the monitoring of the weather conditions we have a number of trials fungicide trials out in in different farms you know it's it's difficult because blast doesn't show up every year and and a lot of times like Jim Cook says you know if you want to make sure you don't have any disease you know let us put a trial in your field and for sure you won't have anything so that happens a lot if we get blast in any of our trials that you know we'll get some data but if we don't then unfortunately we can't get any data like that.

SPEAKER_02: 15:59

I have one more question for you, and this is a little off the beaten path. So there have been disease surveys that UCs put out over the last several years or so. I think the last one was in 2019, and then there's another one coming out this year. Can you give us a bit of information about what the disease survey is and what kind of information UC gets from it?

SPEAKER_00: 16:21

Yeah, this disease survey is very important because it's what allows the right industry to continue to have a burn allocation. So when the phase down of burning came about, some acreage was allowed to be burned for disease management. And initially, you know, to be able to burn, you had to show somebody had to come to your field and inspect it and make sure you had the disease so that you could burn it. But now we kind of just, you know, do it more of an industry wide scale. And so we do a disease survey. We've done it. I think the first time we did it was 2014. You know, the Rice Commission supports us on that. And the Rice Commission uses the data we generate to go to the Air Resources Board and show how much disease we have. You know, if for whatever reason, say, we started to see that, yeah, stem rot is not a problem anymore. And, you know, we haven't seen any blast. And, you know, Colonel Smut is no longer around. Maybe you could justify not burning... as much acres. We don't burn that many anyway, but it's always good to have at least the possibility of burning some of the acres. So that's what we use the survey for, is to show that we have diseases and we need to manage them. A great way to manage, to reduce the amount of inoculum is burning. So what we do is we just go through the Sacramento Valley and kind of randomly select fields where we go and we rate for disease presence. And we look for our forming diseases. So we look for stem rot, aggregate shispa, kernel smut, and blast, and just document their presence. That gives us a good idea of how much disease we get and how widespread they are.

SPEAKER_02: 18:09

Luis, is there anything else you want to mention about blast?

SPEAKER_00: 18:12

Yeah, well, the other thing I would say, because I do get this question quite often, is like, why aren't all of our varieties resistant to blast? And I mean, the answer is, I'm not a breeder. I'm not one of the rice breeders. But if you ask them, you know, it's not that easy to do. It takes quite a few years to be able to get the blast resistance. into the variety without compromising, you know, the yield potential and the quality of the variety. So it takes time, but I think our breeders know that, you know, blast can be a significant problem and the varieties that they're putting out, they're all going to have some, they're all going to have resistance to blast. So the M210 and then the latest one to come is going to be M521 has resistance to blast as well.

SPEAKER_02: 19:07

For people who don't know, M521, that is a new resistance to oxofluorophane medium grain rice variety. It has been released, but the chemical partner is not yet released. So that partner program is on hold for now.

SPEAKER_00: 19:22

Yeah, it just takes time.

SPEAKER_02: 19:24

Yeah, maybe next year. We'll see. Our upcoming event list looks a little light this week. As we enter into rice harvest, we understand that everyone's getting really busy. So stay tuned for more information about our program after harvest. For more information about the UC Cooperative Extension Rice Research Program, please check out our other resources. These include the UC Rice blog, the UC Agronomy Rice website, and our newsletters, which are Rice Briefs, which covers Colusiolo rice notes, which covers Yuba Sutter, rice leaf, which covers Butan Glen, and rice in the Delta, which covers, you guessed it, rice in the Delta region. Thanks for listening to Thoughts on Rice, a UCANR podcast. You can find out more about this podcast on our website, thoughtsonrice.buzzsprout.com. We appreciate you listening. And like the growers like to say, have a rice life. Mention of an agrochemical 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. The views, thoughts, and opinions expressed are the speaker's own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general purposes only. The University of California name and all forms and abbreviations and its use does not imply endorsement of or opposition to any specific organization, product, or service.