Rice production in the Sacramento-San Joaquin Delta region has been steadily increasing in recent years. While Delta acreage is only a fraction of that in the Sacramento Valley, Delta yields are consistent with statewide averages. I estimate that in 2023, the Delta had around 10,000 acres of rice. In this seasonal recap, I'll overview UCCE research in Delta rice, as well as provide some observations about the 2023 season.
Armyworm Monitoring: I have been monitoring armyworm populations in the Delta since 2016, in collaboration with my UCCE colleague, Luis Espino. Monitoring involves scouting for damage and deployment of pheromone bucket traps that catch the moths. We can use trap counts and Growing Degree Day modelling (i.e. a temperature measure of time) to determine whether and when to treat fields. In 2023, we were thinking we might get away with minimal pressure because the population stayed low through early July. Then, the population spiked in mid-July, later than we had ever observed (Fig. 2). We surmise this was due to the cool, wet spring and later planting season. This year, Methoxyfenozide (Intrepid 2F) was available for use under full registration.
Disease Observations: We have identified diseases like stem rot, aggregate sheath spot, and rice blast on some Delta farms. It is important to scout for these diseases at late-tillering and early-heading because treatment timing is critical for management. Fungicide treatments are most effective when applied between late-boot and early-heading. Rice blast may be exacerbated by too much nitrogen, and stem rot and aggregate sheath spot by low potassium (K). K can be limiting in some Delta soils, especially where the straw is baled. There is a loss of approximately 28 lb K/ac for every ton of straw removed. Consider leaf tissue sampling for K between tillering and panicle initiation. The Y-leaf should have a K concentration of at least 1.5%. At heading, the flag leaf should have a K concentration of at least 1.2%. On-farm consultations are a service provided by UCCE. Please reach out if I can help identify pests and provide management guidelines.
Weedy Rice: We should continue to keep weedy rice on our radars because we have observed it in the Delta. In-season management includes rogueing or spot spraying before viable seed is produced. The organic herbicide Suppress is registered for spot spraying. Post-harvest management should include straw chopping, but not incorporation, and winter flooding. This will keep seed on the soil surface, where it can potentially deteriorate over the winter.
Variety Trial: UCCE collaborates with the California Rice Experiment Station to evaluate commercial varieties and advanced breeding lines. The San Joaquin County Delta location was one of ten locations in the 2023 statewide trial. The Delta is a test site for very-early maturing varieties because it has cooler growing conditions than other rice growing regions of the state. Variety trial results will be made available in the February 2024 newsletter.
Cover Cropping: With funding from the CDFA Healthy Soils Program and CA Rice Research Board, I am collaborating with Sara Rosenburg (UC Davis graduate student) and Whitney Brim-DeForest (UCCE rice advisor) to evaluate winter cover crops. We are interested to learn whether cover cropping improves soil carbon and nitrogen dynamics in the rice system. Since rice may be grown over multiple seasons without rotation, cover crops may provide an opportunity to introduce plant diversity, including nitrogen-fixing legumes. Trials will occur from 2022-2025, and the Delta site is one of three (also in Butte and Colusa counties). The 2022-2023 winter season presented several challenges for cover cropping. At the Delta location, seasonal rainfall exceeded 25 inches, and in the ten days after planting, the site received nearly 3.5 inches of rain. In addition to saturated soils, bird predation was severe. This fall, our aim is to plant earlier, if conditions allow.
Thank you to all the growers who collaborated with us on these projects. I wish everyone a good end to the year and a great 2024.
We invite you to attend a Delta Rice Workshop on Wednesday, August 23rd from 10:00am to noon on Staten Island (23319 N. Staten Island Rd., Thornton). The workshop is collaboratively supported by Fish Friendly Farming, the Delta Conservancy, Conservation Farms and Ranches, the CA Land Stewardship Institute, the Regional Water Board, and UC Cooperative Extension. Organizers will demonstrate the use of a recirculation pump in rice production, with a discussion of potential financial support programs. Additionally, there will be a presentation on The Nature Conservancy's Bird Returns Program, and I will provide an update on UCCE research in Delta rice.
The agenda is below, and more information is available from the attached flyer. CDFA INMP (1.0) and CCA (1.0 SW, 0.5 CM) continuing education credits have been approved. We hope to see you at the meeting!
Fish Friendly Farming and Delta Conservancy/Regional Board funding - Laurel Marcus, FFF
Recirculation Pump System - Jerred Dixon, Conservation Farms and Ranches
Can funding programs such as SWEEP be used for recirculations pumps and pipelines - Laurel Marcus, FFF
Bird Returns Program - Julia Barfield, TNC
Research Activities in Delta Rice - Michelle Leinfelder-Miles, UCCE
Diagnosing problems in the field is never an easy task, but it is one of the most interesting aspects of my job because I usually never encounter the same set of circumstances twice. This summer, I have been called out on a few interesting diagnostics calls, and I wanted to share some observations.
I visited a blackeye bean field that was planted at the end of June. Since June was unusually cool this year, the grower's planting was delayed. Blackeyes shouldn't be planted until the soil temperature reaches at least 65 degrees F, and the cool spring conditions kept the soil cool. About six days after planting, the beans were only sporadically emerged. The plants that had emerged looked healthy, but the overall stand was poor. The grower said that soil moisture was good at the time of planting. I scratched down and found the seed about three inches deep, which is perhaps a little bit deep for blackeyes. Seed had germinated, and the germinated seed looked healthy with no apparent seedling diseases. Seedling diseases include Pythium and Rhizoctonia. Pythium symptoms appear as water-soaked lesions, and the hypocotyl eventually ‘dampens off'. Rhizoctonia symptoms appear as reddish-brown lesions that can girdle the stem. We felt better that it didn't appear to be a disease problem. I reached out to my farm advisor colleague, Rachael Long, to get her take on the situation, and she agreed that this was likely delayed emergence due to cool soil and a deeper planting depth. In the end, we decided to test our patience, wait a few more days, and see what would happen. After another five days, the grower let me know that the plants had emerged, and the stand looked good!
The UCCE network has a breadth of experience to help identify problems and provide potential management solutions. Please don't hesitate to contact me if you'd like help with diagnosing problems in the field.
We can use trap counts and Growing Degree Day modelling (i.e. a temperature measure of time) to determine whether and when to treat fields. UC IPM provides treatment guidelines that include damage assessment and signs of the worms in the field. Earlier this year, Methoxyfenozide (Intrepid 2F) received full registration, so we now have a new tool in the toolbox when treatment is necessary.
The monitoring that I do in the Delta is part of a larger effort that is spearheaded by my colleague, Luis Espino, rice advisor in Butte and Glenn counties. Luis writes a weekly blog to provide real-time information on trap counts to help growers and consultants with scouting and decision making. In his blog announcements, he will link to an interactive mapping tool called Ag Pest Monitoring, where you can view counts across trapping locations. Please consider subscribing to Luis Espino's blog, but don't hesitate to reach out to me if you'd like to discuss what is happening in the Delta.
Good luck this season, and I hope to see you in the field!
University of California Cooperative Extension and the UC Davis Department of Agricultural and Resource Economics collaborate on cost of production studies for commodities grown in California. The purpose of the studies is to provide sample costs for producing commodities and expected returns, based on current production practices and economic conditions.
We have recently published a study for Sacramento-San Joaquin Delta rice production, available here. The study is based on a hypothetical 1,100 acre farm, where 1,000 acres are annually planted to rice, and it details the unique production conditions and practices of the Delta. The study assumes the farm's soil has high organic matter and employs drill-seeding (Figure 1). This soil type and planting practice differs from Sacramento Valley conditions, where rice is water-seeded onto mineral soils with high clay content. Nutrient and pest management practices also differ between the regions; hence, the study will more accurately reflect the costs associated with Delta rice cultivation. The study details the operating costs associated with Delta practices and the total costs for farm operation and management. A ranging analysis presents potential returns based on typical yields and recent crop pricing.
The study also details the costs associated with converting land from other annual crops to rice, including levee construction and land leveling. Conversion costs are significant and can inhibit adoption of rice cultivation because they may take years to recuperate.
We thank the growers who contributed their time and expertise to informing this study. Please don't hesitate to reach out to me if you have any comments or questions.