The trial was planted in a field of CB46, and fertility and pests were managed by the grower in the same manner as the field. Data are presented in Table 1. Stand counts were made approximately two weeks after planting on July 20^th. The stand was assessed as the number of plants per two-foot length. Twelve replicate counts were averaged. We evaluated aphid and lygus damage on September 8^th, which were low due to the grower's management. For lygus, we took 10 sweeps from four locations in each plot and counted the lygus. Data were averaged and are presented as a 10-sweep count. For aphids, we used a rating scale from 0 to 10 that accounted for visible crown damage and aphid incidence. In addition to the in-field assessment of lygus, we also evaluated harvest samples for stings and found that, on average, about 1.2 percent of the beans had lygus damage. No diseases were observed.

We harvested on November 6^th. All six rows of each variety were cut and raked into one windrow. At the time of cutting, the grower observed that CB77 plants were laying flat, but they were laying in such a way that the knives still picked up the plants. The grower also observed that CB74 had an upright growth habit that could potentially make it a variety viable for swather cutting. We evaluated 100-seed weight as a measure of seed size, evaluating five 100-seed samples per variety.

We would like to thank the cooperating grower, the CA Crop Improvement Association for funding regional trials, and the CA Dry Bean Advisory Board for assistance with statewide research prioritization and assistance with outreach.

Table 1. 2023 Blackeye Bean Variety Evaluation Results

The trial was drill-seeded on April 27^th at a rate of 150 lb/acre, and varieties were replicated three times as 150 ft² plots. The trial was planted in a field of M-206, and fertility and pests were managed by the grower in the same manner as the field. We harvested the trial on October 12^th, and yield was determined by hand-harvesting a 15 ft² area from each plot.

Table 1 shows results from the Delta location (advanced breeding lines omitted). Among the entries, M-206 is the most commonly planted variety in the Delta and across the state. It has good agronomic characteristics and consistent quality across different harvest moistures. Some Delta growers also plant M-105, which is a very-early variety that has yielded well in Delta trials but may be slightly more susceptible to rice blast disease than M-206. Among the newer varieties, M-210 is early maturing, blast resistant, and may be a good option for the Delta. While variety M-211 performed well in 2023, it is not as well adapted to cooler environments as M-210 and has had variable performance over the last three years (Table 2). Also, M-211 quality tends to decrease below 18 percent harvest moisture. Statewide results of all nine testing locations will be available soon from the UC Rice Research and Information Center.

Special thanks go to the cooperating grower. Thanks also go to Bruce Linquist and Ray Stogsdill, UC Davis, for coordinating the statewide effort, and the CA Rice Research Board for funding. If you have questions about the trial or about Delta rice production, please don't hesitate to reach out to me, and good luck in 2024!

Table 1. 2023 Delta rice variety trial results.

 

Table 2. Three-year Delta trial yield summary (lb/acre at 14% moisture).

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. 

Fig. 1. The herbicide, Loyant, was trialed on cattails in 2022 and 2023. We observed good control when cattails were less than 3 feet tall.

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.

Fig. 2. Delta true armyworm trap counts, 2016-2023. In 2023, the population was late to peak, likely due to the cool, wet spring and late planting season.

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.

UC Cooperative Extension collaborates with the California Rice Experiment Station to evaluate commercial varieties and advanced breeding lines. The San Joaquin County Delta location was one of seven locations in the 2022 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. The trial was drill-seeded on April 19^th at a rate of 150 lb/acre and harvested on October 2^nd. Plot size was 150 ft², and varieties were replicated four times. Table 1 (below) shows variety results at the Delta location (advanced breeding lines omitted). Among the entries, M-206 is the most commonly planted variety in the Delta and across the state. It has good agronomic characteristics and consistent quality across different harvest moistures. Some Delta growers also plant M-105, which is a very-early variety that has yielded well in Delta trials but may be slightly more susceptible to rice blast disease than M-206. Among the newer varieties, M-210 is early maturing, blast resistant, and may be a good option for the Delta. Variety M-211 is not as well adapted to cooler environments, like the Delta, and quality appears to decrease below 18 percent harvest moisture. One of the advanced breeding lines, which is not shown in the table below, but which yielded better the M-206 in the Delta trial, will become CH-203. For a comparison of yield across all seven trial locations, please see the recent edition of the UCCE Sutter-Yuba newsletter. Special thanks go to our grower cooperators for hosting the variety trials. If you have questions about the Delta trial or about Delta rice production, please don't hesitate to reach out to me.

UCCE will host two upcoming meetings for the rice industry:

1. The 2023 Rice Production Workshop will be held March 15-16 at the Lundberg Family Farms facility in Richvale (5311 Midway, Richvale, 95974). This is an in-depth workshop that covers the principles and practices of rice production in California. The workshop is directed toward folks who are new to growing rice or serving the rice industry. The program is available here. Registration is limited, so please sign up early. The registration fee covers the workshop manual and lunches both days. We have applied for DPR, CCA, and CDFA nitrogen management continuing education credits.

2. The Cover Crops in Rice Field Demonstration Day will be held March 27 from 10:00am to 12:00pm. The field day will be held at the corner of Hwy 45 and White Road, Colusa, 95932 (38.969148, -121.866552). At the field day, we will discuss the CDFA Healthy Soils Program, and attendees can walk through the cover crop trial. No registration is required. We have applied for CCA and CDFA nitrogen management continuing education credits. The agenda is attached below.

Table 1. 2022 San Joaquin County rice variety trial results.