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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
1.2 - Bakanae symptoms in the Sacramento Valley
Together, the UCCE Farm Advisors seek to provide relevant, topical research-backed information relating to CA rice production. Sarah Marsh will be discussing the issue of bakanae in rice. This topic has come up with some frequency in recent weeks.
Upcoming Events!
- UCCE Hedgerow Demonstration Day on August 14
- Annual Rice Field Day on August 28
- Rice Pest Management Course on September 4 *registration required*
Bakanae Resources
Integrated Pest Management for Rice, Third Edition. UC Agriculture and Natural Resources.
Compendium of Rice Diseases and Pests. Second Edition. 2018. American Phytopathological Society Press
Invasion and Colonization Pattern of Fusarium fujikuroi in Rice
Chieh-Yi Chen, Szu-Yu Chen, Chun-Wei Liu, Dong-Hong Wu, Chien-Chih Kuo, Chun-Chi Lin, Hau-Ping Chou, Yu-Yao Wang, Yi-Chen Tsai, Ming-Hsin Lai, and Chia-Lin Chung. Phytopathology® 2020 110:12, 1934-1945
Other Resources
Rice in the Delta
Feedback Poll
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.
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Sarah: 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.
Whitney: I'm Whitney Brim DeForest. I'm the Cooperative Extension Rice Advisor for Sutter, Yuba, Placer, and Sacramento Counties.
Luis: My name is Luis Espino. I'm the Rice Farming Systems. advisor for Butte and Glenn counties.
Michelle: 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.
Sarah: Together, the UCCE Rice Farm Advisors seek to provide relevant, topical, research backed information relating to California rice production. Today I'll be discussing the issue of bakanae in rice. This topic has come up with some frequency in recent weeks. I'll be discussing a little bit about the bakanae symptoms to look out for, as well as different management techniques that are available across the different rice systems we have in California.
Some of the other rice advisors and I have been getting calls about tall, light colored plants in rice fields. These plants arch over the existing crop, but they are a lot lighter in color. When the growers and PCAs go to check them for the ligule, which would differentiate them between rice and members of the Echinocloa species.
The plants do have the characteristic ligule of rice. When we go out to see these reports, we're noticing that the symptoms of these light colored plants are consistent with rice infected with bakanae. bakanae is a seed borne disease that causes seedlings to appear chlorotic, thin, and elongated, with affected plants arcing high above healthy rice plants.
Now bakanae was first identified in California in 1999, but it is not a new disease in the rice world. bakanae is one of the oldest known diseases in rice in Asia, and is also one of the most damaging. bakanae is caused by the fungus Fusarium fujikoroi . The fungus produces the plant hormones gibberellin and fusaric acid.
Gibberellin is responsible for, among other things, stem elongation, while fusaric acid is a metabolite that creates phytotoxic symptoms in plants, including chlorosis. Together, these compounds cause infected plants to elongate and or become chlorotic. The symptoms of bakanae can change throughout the growing season.
Symptoms of bakanae first appear about a month after planting, with infected seedlings looking elongated, spindly, and chlorotic. In mature plants, the symptoms appear when the leaves turn yellow, and they become easily seen above the canopy. Most plants die prior to producing a panicle. If a panicle is produced, the kernels do not fill.
Another way to identify bakanae in rice is to take a look at the crown of the roots. When the crown of the roots is sliced, it appears discolored and rotted. There will be pictures available on our website and linked in the show notes to exemplify a little bit about what I'm talking about. At maturity, the pathogen produces pink spores on dying tillers.
These spores can infest seed coats during harvest, including the seed coats of rice in nearby fields. bakanae is considered a seed borne disease, meaning that the main way the disease is spread is via seed, which is the most important source of inoculum. The bakanae pathogen overwinters as spores on the coat of infested seeds.
It can also overwinter in the soil and plant residue, but this is not thought to be an important source of inoculum. Some species of water grass can also act as host of the disease. The best way to prevent bakanae infestation is to use rice seed that is free of the pathogen. This means avoid using infected fields as seed fields.
The most effective way to eliminate bakanae spores from seed is to use sodium hypochlorite, also known as bleach, as a seed treatment. There are two ways to use bleach in a soak seed treatment. The first is to dilute bleach in water to prepare a 3, 000 parts per million chlorine solution. Soak the seed for two hours.
drain, and then soak the seed in fresh water until ready for seeding. The other way to use bleach is to soak the seed in a 1, 500 parts per million chlorine solution for at least 24 hours. With this method, there's no need to drain and soak in fresh water before seeding. As a reminder, these statements are not recommendations, merely the results UC Studies.
Follow the label. The label is the law. To prepare the chlorine solution. Use only registered sodium hypochlorite products and follow the instructions on the label. Products have different concentrations of sodium hypochlorite, and therefore the amount of product needed to reach the right chlorine concentration varies.
A fact sheet with the list of currently available products, as of this podcast episode, will be linked in the show notes. Rice seeds should be sown within 12 to 24 hours of draining. However, if the seed is drained and held without water for more than a day before seeding, the seed can warm up. This increase in temperature can allow for any surviving Bacchinae spores to germinate and produce more spores.
which can cause infestation even in seeds that have been treated. Essentially, if the seed is held without water for too long, the treatment is negated and no longer has much efficacy. Currently, no effective seed treatments against bakanae exist for organic, dry, or drill seeded rice. Given that most of the rice acreage in California is conventionally grown and water seeded, Wide adoption of the sodium hypochlorite seed treatment can reduce the area wide bakanae inoculum and reduce the risk of infection and contamination of seed for organic, dry, and drill seeded rice growers.
At present, the most effective strategy for rice growers who use organic, dry, or drill seeded methods relies on their neighbors using the bleach treatment on their conventionally grown rice. So back to the reason we're talking about bakanae. Why have we been getting calls from growers who are seeing bakanae in their fields?
Although the disease initially posed a threat to the industry when it was first observed in California because it caused yield reductions in heavily infested fields, after the adoption of the sodium hypochlorite seed treatments, the importance of the disease declined, rarely causing losses. However, in recent years, the disease has regained importance as use of the sodium hypochlorite seed treatment has decreased.
There are a lot of reasons as to why that might be, but decreasing use of the bleach treatment does have long term effects for the fate of boccone in California rice. This year, the most severely affected fields we have seen have been in fields planted with seed not treated with sodium hypochlorite.
According to the UC Rice Production Cost Study from 2021, the cost to soak seed in a bleach solution is approximately 1. 75 / cwt now this information is about three years old, but after speaking to growers in the area who did use the seed treatment this year, this holds true. Relatively speaking, it's not a high cost to pay, especially since it's currently the only way to sanitize seed against bakanae.
So, to sum up, if you see tall, light colored rice plants in the field, and the crown of the root is brown and rotted, the plants may be infected with bakanae. Check with your PCA or local farm advisor to be sure. If you use continuous flooding and haven't been using a bleach soak for your rice, you It might be worth considering for next year.
For further information about bakanae and rice, there are several resources available online, which will be linked in the show notes and on our website. Some of these resources are listed below. The UC Rice bakanae Fact Sheet, Integrated Pest Management for Rice, published by UC Agriculture and Natural Resources.
UC IPM for Rice, found at ipm. ucanr. edu. And finally, the Compendium of Rice Diseases and Pests, Second Edition, published by the American Phytopathological Society Press.
We have a series of upcoming events relating to rice farming and production. August 14th, we will have our UCCE Hedro Demonstration Day. This will be a field day to discuss a new project, studying the effects of hedgerows in rice systems. We are fortunate enough to have a grower collaborator helping us with this project, and this demonstration day will be at the corner of Lodi and Tule Roads in Grimes.
The next event on our docket is the annual Rice Field Day, which will be August 28th. The agenda will start promptly at 8 and go until noon and consist of field tours, talks from the rice breeders, and lunch. Our final upcoming event is the Rice Pest Management Course, which will take place on September 4, which is the first Wednesday of September on the week of Labor Day.
Registration is required for this event. This event will start at 8 and go until 3 p. m. and will consist of riced field tours with new chemicals. breakout sessions for Pest ID, lunch, and an afternoon session concerning pest management in rice. Links for more information and registration will be included in the show notes, as well as in our various newsletters.
These newsletters are the Rice Briefs Newsletter, which covers Colusa and Yolo counties, the Rice Notes Newsletter, which covers Yuba Sutter counties, and the Rice Leaf Newsletter, which covers Glenn and Butte counties. This information and more is also found on the UC Rice blog and the UC Agronomy Rice website, which are both linked below.
Thanks for listening to Thoughts on Rice, a UC A N R podcast. You can find out more about this episode and this podcast on our website. thoughtsonrice. buzzsprout. com.
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 are the property of its owner, and its use does not imply endorsement of or opposition to any specific organization, product or service.
