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Thoughts on Rice
This podcast is for growers, PCAs, consultants, and other industry professionals in the California rice industry. We'll primarily be focusing on the Sacramento Valley and Delta Region of California. The UCCE Rice Farm Advisors aim to deliver extension information relating to the California rice industry.
Find out more about UCCE and California rice here!
Thoughts on Rice
Herbicide Resistance Testing Program with Kassim Al-Khatib
Together, the UCCE Farm Advisors seek to provide relevant, topical research-backed information relating to CA rice production.
Sarah Marsh Janish sits down with Dr. Kassim Al-Khatib, who is responsible for the Herbicide Resistance Screening Program that UC Cooperative Extension provides, free of charge, to rice growers and PCAs who are interested in determining the herbicide resistance status of their rice weeds.
Herbicide Resistance Testing Form
Resistant Weed Seed Testing Resources
Mention of an agrichemical does not constitute a recommendation, merely the sharing of research findings. Always follow the label. The label is the law. Find out more at ipm.ucanr.edu.
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.
UCCE Upcoming Events - SAVE THE DATES:
- No-Till/Reduced Till Rice Field Day, June 10, 2025
- Rice Production Workshop, POSTPONED TO MARCH 2026
- Weedy Rice Workshop, August 5, 2025
- Rice Field Day, August 27, 2025
Other Resources
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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 Marchionish, and I'm a rice farm advisor for Colusa and Yolo counties.
SPEAKER_00:I'm Whitney from DeForest. I'm the Cooperative Extension Rice Advisor for Sutter, Yuba, Placer, and Sacramento counties.
SPEAKER_04:My name is Luis Espino. I'm the Rice Farming Systems Advisor for Butte and Glynn counties. I'm Michelle
SPEAKER_03: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:Together, the UCCE Rice Farm Advisors seek to provide relevant, topical, research-backed information relating to California rice production. Today I have the privilege of sitting down with Dr. Qasim Al-Khatib, who's the Melvin D. Andros Endowed Professor for Weed Science and Specialist in Cooperative Extension at UC Davis. Qasim's career started with a Bachelor of Science in Agronomy from the University of Baghdad, followed by a PhD at Kansas State University, after which he spent time in Extension and Research at Washington State and Kansas State before heading west to UC Davis. Qasim's Thank you. and the environment. Kasim is responsible for the herbicide resistance screening program that the UC Cooperative Extension provides, free of charge to rice growers and PCAs who are interested in determining the herbicide resistance status of their rice weeds. I've asked Kasim to talk about the herbicide resistance screening process and tips for weed managers when it comes to collecting and submitting weed samples for testing. Hi, Kasim. Thanks for making the time to be here today. Hi,
SPEAKER_01:Sarah.
SPEAKER_02:Let's talk a bit about your background and education and how you came to be here at UC Davis.
SPEAKER_01:Yeah, I am here in UC Davis as a professor of weed science and also weed specialist. Before that, I was the state director for UC IPM program. And before that, I was a professor at Kansas State University. That's the place I went to school to I spent about 15 years there. But before going to K-State, I was also a weed specialist at Washington State University. Currently, I do research, teaching, and extension. My research focus on weed biology and weed management, herbicide-resistant weed, and off-target herbicide movement, which many people call it herbicide drift. taught many classes, including weed science, herbicide interaction, integrated weed management, integrated pest management, physiology of herbicide resistance. I also supervise graduate student and postdoc, in addition to do extension work with the growers on different aspects of weed management.
SPEAKER_02:All that to say, Kasim, I think you stay pretty busy. Well, you mentioned herbicide resistance, and that's kind of why we're talking today. As we all know, the state of herbicide resistance in California rice weeds is probably one of the highest, at least in the United States. So let's talk about how herbicide resistance typically develops in plants.
SPEAKER_01:Sure. Well, herbicide resistance means that the weed withstand herbicide treatment, which originally is susceptible to. So the weed develop resistance. Now the question, how how that happened. You know, when you take one single weed, take a population of that weed, phenotypically, they look the same. But if you look at this plant, and if you take a million of these plants, you will find a few plants, maybe one plant in a million, has slightly different genetic background. And with this genetic background, that single plant can survive herbicide treatment. So when a grower or a person keep using that herbicide, the herbicide will kill all the susceptible plants over time. It's not going to take one year to do it, but if you do it over time, will it clean the susceptible plant? And what you have left is that single plant I talk about it, which has a genetic makeup that resists the herbicide. That single plant will produce seed and over time build the population and that population is resistant to the herbicide now how that happened well it's a species dependent some species they have more genetic diversity than others those these are the species that will develop resistant wicker if the grower continue use the same herbicide or herbicide belong to the same mode of action that will accelerate the rate of development of resistance. If the grower does not do crop rotation, which we're going to talk about that, that also can lead to faster resistant development. In addition, if the person doesn't use other method of weed control, mechanical, cultural, good cultural practices, biological, all these lead to development of resistant equator.
SPEAKER_02:Great answer. And I'm glad you touched on crop rotation. and how it can affect herbicide resistance. Because I do want to talk about rotation in general and not just crop rotation, but also rotating the modes of action when it comes to the chemicals you're using. Can you talk about how rotating modes of action can help fight against the rise of resistance in weeds?
SPEAKER_01:Well, if you take rice, for example, this is the crop we're talking about here. We have probably 12 different herbicide regions table on rice. Six of those belong to the same mode of action. So if we develop resistance to one of these six, in general, they will develop resistance to the other six of the herbicides. So you lost half of what you have in your hand because of this resistance. So probably the good way to use herbicide is to rotate the mode of action. Don't rely on one mode of action and you repeat using that mode of action. Other thing you could do is mixing two herbicides with two different mode of action that they can kill that weed. And with that also, we will help preventing or delaying resistance. This is for chemical standpoint. Rotation for crops also can help. And I fully understand in rice we have limitation because the soil is heavy, does not accommodate different crops, but anytime you do a crop rotation, you delay the resistance. This is another thing you need to do if you can. Other factor that you can consider is to control weeds before you plant rice, which we call it the still seed bed. I know this is difficult sometimes because of weather conditions, but this also will help because you can get rid of the weeds before they grow in the crop.
SPEAKER_02:And for people who might be less familiar with the stale seedbed, let's go into, I guess, how that looks in our rice systems.
SPEAKER_01:Well, in rice systems, you know, what you need to do is there are multiple ways you can do it. One way is after you work the ground, there are weeds that are going to come up. You can flush the field with water or even if you get enough rain, weeds will emerge. And what you need is to come and control these weeds. You can control them chemically. You can control them by disking the ground. And that will reduce the level of weeds in your crop, in the unseasoned crop.
SPEAKER_02:Thanks for clarifying that. Now, just to kind of narrow in on California rice, because that's what we're going to really focus on here. Let's talk about why herbicide resistance is such a huge problem in California rice in particular compared to other systems.
SPEAKER_01:Sure. I think it's a very serious problem here in California. It's affecting the sustainability of the rice cropping system. As I said earlier, we had about 12, 13 herbicides and half of them belong to one mode of action. We do not use quite a bit of crop rotation. There is no many weed control methods. Our growers are very good. They use a clean seeds, so they don't introduce weeds to their field. They control weeds on the levees, ditches. They use high seeding rate to suppress weeds. They use water, another thing, you know, deep water, so they suppress weeds. So they use multiple things. But herbicide, you know, continue to be the main method of weed control. And as I said earlier, we don't have too many herbicides. And when growers continue you use the same mode of action, it will result of resistance. We did quite a bit of research and we found that we do have resistance in certain population to two, three, four, even five mode of actions. So this is a challenging to control these weeds with multiple resistance to multiple herbicide. But again, you know, not rotating herbicide, no crop rotation, limit methods of weed control all led to this serious problem in California rice.
SPEAKER_02:Absolutely. I'm really glad you summarized it like that. But because I guess there's been such a history of strenuous weed populations in California rice, weeds that are able to overcome essentially everything that the growers and researchers have thrown at them, is that part of the reason why the herbicide resistance testing program that you currently have head up began?
SPEAKER_01:Yes, that's absolutely right. You know, we try to help the growers to identify what resistance they have. This is a key point in management. You need to know what resistance you have so you know what herbicide to use to control weeds. You know, instead of trial and error, instead of shooting in the dark, they will have data that they can rely on and use the right herbicide to control these weeds.
SPEAKER_02:How long has the program been open to growers and PCAs?
SPEAKER_01:Well, it was a program in a place for some time. But in 2015, we start this, you know, extensive program. You know, this program, as I said, 2015, we start. It's supported by the RISE Research Board, California RISE Research Board. So we started actually in 2015. the modifier program. Before that, we did some testing here and there, but we didn't have really a formal program.
SPEAKER_02:Okay, that makes a lot of sense. So since you talked about the formal program, can you explain the steps that are involved from beginning, from a weed manager or a grower seeing suspected herbicide resistance in the field, all the way to the end of what that process looks like?
SPEAKER_01:Sure. So if the farmer or the PCA think they have resistance, they collect seeds. And probably we'll talk about that later on. But they collect seeds. They take it to the UC farm advisors or they bring it to the RISE experimental station in Bix. We require a certain amount of seeds. We require the seeds to be mature. and quality seeds, then some of the weeds, they have dormancy. They don't germinate. So we break the dormancy for these weeds. We have our method, what we do to break the dormancy. After we break the dormancy, then we grow these plants in the greenhouse and we treat a weed, a certain weed, every weed actually, a species, with the herbicide label on that weed. So if If we have watered grass, for example, we treat it with all herbicide that's supposed to control watered grass. And then we look at the response of the weeds. And in the end, we take data for the response. We take photo for the response of this population. And then we send a report to the grower to tell her or him, this is the resistance you have. This is the herbicide that control your weed, and this is the herbicide you need to avoid them because your weed has resistance to these herbicides. This is kind of summarized what we do, but there are a lot of details in between.
SPEAKER_02:I guess in order to make sure that, say I'm a grower and I'm going and collecting my seed, to get the most important information out of that report, getting that good quality seed, like you mentioned, is really vital. But since the weed seeds mature at different points throughout the season, you guys must be receiving seed sample submissions probably all rice season, probably a little bit after harvest has begun, huh?
SPEAKER_01:We have directions to the growers. It's on the EOC RISE website, how they collect the seeds. The website also has a video how you do that. So we ask growers to collect seeds at maturity and take a a paper sack, put them by the head of the weed and put the head in the back and try to shake the head and the head will drop the mature seeds in the back. So we will have seeds for us to test it. Now, we ask also growers to be careful because some of the weed shatter early. So they may need to collect these weeds before they shatter. So for example, springle top, it shatter quickly after the panic will develop. So they need to pick those seeds. Then you have early water grass come after that. Barren yard grass come after that. And then you have the common weeds like the small flower, bulrush. And in the end, you have late water grass. So they need to go after these weeds in the right stage so you don't collect them and also you don't allow them to shatter and then you don't have seeds to collect. If they collect green seeds and send this to us, there's two things can happen. The seed can rot in the back or they will not germinate and that create a problem. And we have some cases where we told the growers or PCA that your seed was not good quality and we cannot give you the
SPEAKER_02:results. That makes sense. So there are a couple of reasons then that a sample might be unusable.
SPEAKER_01:Correct, correct, correct.
SPEAKER_02:And then when you send the report, let's talk about just like confidentiality. Who sees a report that gets sent in the program?
SPEAKER_01:Well, as I said earlier, generally growers give us the seeds sometime late September, early October. By end of October, we start the process of doing the screening as I described earlier. Then in the end, we will have the results and send it to the growers. This is very confidential. We ask the grower to give us some information, some sort of where is the field is, what's the history of the field, what herbicide they use in the field, and that will help us in making decision and recommendation to the grower. What's their contact information, their phone number. If we run into a problem, we call the grower or PCA to tell them this is a problem we're facing. And to answer your question, it's very confidential between us and the person who sent us this. Nobody else will see the results.
SPEAKER_02:Fantastic. Right. I know that there's been some state or countywide reporting of resistance, but it's never tied to an individual field or an individual grower. I think the most localized it gets is countywide basis.
SPEAKER_01:Sure, sure. And one thing I didn't mention that we tried to send the results to the growers sometime in mid-March so they can make decision about what to use for the coming season because they need to buy chemical, they need to make an order, and with that, we will give them the information. For example, this year, we sent the last report two days ago. So all the growers received their report. They know what resistant they have and they know what chemicals they need to buy.
SPEAKER_02:Sounds great. Sounds very valuable information. I guess from a more research standpoint, let's move on and talk about some of the most important lessons that we've learned from the herbicide resistance testing program as a whole.
SPEAKER_01:Well, that's a good question, Sarah. You know, we get samples like it depends on the year. Some year we get more than 100 samples. Some of them we get about 40, 50. It depends on the year, what they face, and so forth. Half of the sample we received, they show no resistance. And what does this tell us? That there is other issue that the farmer did not get good control of the weeds with the herbicide they use. It could be environmental, could be the way they surprise the chemical, the timing of the application. There's multiple things can cause this lack of response. But half of the cases, most of the time we see resistance at least one mode of action. So the lesson we learned that we do have extensive herbicide resistant spread across all counties. Some of the resistance are multiple resistance. Some of them resistant to more than three or four herbicide, which is difficult to manage at this stage. We're working on alternatives. We're working on recommendation, what we need to tell these people what to use. And when they receive the report of roma, us, we give them this information. You know, we recommend certain things to the growers to consider.
SPEAKER_02:Where can people who are interested find the herbicide testing form? And is there a website or a place you want to direct them to to look for it?
SPEAKER_01:Yeah, if you go to the to Google you see rice website it will take you to the website and you can click on the weeds and under that type of the weeds you see multiple information there. One of them about herbicide screening. So the website for the UC rice which is agronomy-rice-ucdavis.com or if you want to go directly to that website which has the information about herbicide resistance screening, you can go to agronomy-rise-ucdavis.edu backslash resistant-weed-seed-testing. You can get the information, all the forms, all the information how you pick the seeds. And of course, I don't know if we talk about this, you need to take the seeds either to the office of your farm advisors, or you bring it directly to the RISE experiment station. We have a box at the door where you put the sample and the form. And in three, four months after that, you will get the result from us.
SPEAKER_02:Yep. And I did just double check with Dustin Harrell at the station on Tuesday, they will have that box up and ready to accept submissions when the season starts. And if no one's there, you can just leave it. We're up at the station, at least one of us every day or so. So somebody will get it. All right, Kasim, is there anything else you'd like to touch on with this program? You've given us a lot to chew on here.
SPEAKER_01:Well, I think we're pretty excited about this program. We think if you have resistance, if you lack control, then you give us a sample. We will help you to make a decision to select the right herbicide. Also, my recommendation to the growers, use all the tools you have in hand. Don't forget good quality seeds, clean seeds, high seeding rate, good water management, control weeds on the levees and the ditches. All these will help you to reduce the impact of weeds on your crop and also delay the resistance.
SPEAKER_02:Fantastic summary, Kasim. Can I ask you to share your contact information if anybody wants to reach out to you further?
SPEAKER_01:Well, you can send me an email klkatib at ucdavis.edu or you can call me at 530-219 And I enjoy it when growers call me about the problem.
SPEAKER_02:I've seen you at the grower meetings, Kasim. It's hard to get you to stop having conversations with growers sometimes. All right. And then with that, I think we'll just wrap up with a final question. Don't worry, this one's not a serious question, but it might be the hardest one to answer. What is your favorite rice to eat, Kasim?
SPEAKER_01:Well, I like the Carlos rice. It's sticky. It's tasty. It stays fresh for a longer period of time. So this is my favorite rice to eat.
SPEAKER_02:Fantastic. Thank you. Wow, you had that answer all ready to go. Okay, Kasim, thank you very much. And we will have you back on the podcast soon.
SPEAKER_01:Pleasure. My pleasure. Thank you for inviting me.
SPEAKER_02:We've got quite a few save the dates here that I'm going to go over. The first is the no-till slash reduced-till rice field day, and that'll take place Tuesday, June 10, 2025. The location for this will be in Grimes at the Gallagher Farm site, and we'll release that information as the time comes closer. But essentially, this field day will be an opportunity for UC researchers to share what we've been learning about using reduced tillage or Again, that's the No-Till, Reduced-Till Rice Field Day, Tuesday, June 10th. The next upcoming event will be the Rice Production Workshop. That's a two-day event. That's Wednesday and Thursday, July 23rd and the 24th. And that's going to be a workshop where we talk about the principles and practices of rice production in California. This workshop only comes around every two years, so we're very excited about this. And the location of that is still TBD. We'll also be hosting a weedy rice workshop on Tuesday, August 5th, 2025. That location is also to be determined, but it will be in the Delta. And this workshop will talk about all of the current UC research regarding weedy rice in California rice systems. Finally, the California Rice Field Day will take place Wednesday, August 27, 2025 at the California Rice Experiment Station in Biggs, California. If you've been to this before, you know it's a pretty much all-day event, a great opportunity to not only see the UC research, but also the research that the rice breeders are undertaking up at the Rice Experiment Station, as well as the opportunity to partake in a delicious lunch. Again, that's the Rice Field Day, Wednesday, August 27th at the Rice Experiment Station in Biggs. For more information about these and upcoming events, feel free to check out our resources, which include the UC Rice blog and the UC Agronomy Rice website. In terms of other resources you might like to take advantage of, you can also look at our newsletters, which include Rice Briefs, which covers Colussiolo, Rice Notes, which covers Yuba Sutter, Rice Leaf, which covers Butan Glen, and Field Notes, which covers rice in the Delta Reef. in the region. Thanks for listening to Thoughts on Rice, a University of California Cooperative Extension podcast from the University of California Agriculture and Natural Resources. You can find out more about this podcast on our website, thoughtsonrice.buzzsprout.com. We'd love to hear from you, whether it's from using our text link in the show notes, a survey submission in our feedback form, also in the show notes, or in a comment or rating on your podcast Thank you. Thank you. Thank you. In this area, we've seen growers starting their field prep, and so we know that rice planting is just around the corner. Stay safe out there, and remember, 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.ucano Thank you.
