- Author: Michelle Leinfelder-Miles
- Posted by: Gale Perez
In 2022, I estimate rice acreage in the Delta, south of the Yolo Bypass, was at least 8,000 acres. Most Delta rice is grown in San Joaquin County, but there is some acreage in Sacramento County. While Delta rice acreage is relatively small compared to that in the Sacramento Valley, it has been steadily increasing over the last several years (Table 1).
Given the increasing interest in rice production among Delta growers, and the differences in production practices from the Sacramento Valley, UC Cooperative Extension and UC Davis will be releasing a cost of production report specifically for Delta rice later this year or in early 2023. A Delta rice cost study was last produced in 2007, so updating the study was long-overdue. I want to thank all the growers who participated in a focus group to update the study.
Cool temperatures can make the Delta a challenging place to grow rice. Low night-time temperatures can cause blanking, which results in empty grains. Growers are limited to using only very-early and early maturing varieties. Most of the Delta acreage was planted with variety M-206, but some growers also planted a portion of their acreage with M-105. In 2022, we continued the UCCE Delta variety trial, which will help to identify and advance cold-tolerant varieties. The Delta trial is part of a statewide network of trials, led by UC Rice Extension Specialist, Bruce Linquist, and coordinated by Staff Researcher, Ray Stogsdill. I anticipate that the statewide results will be ready in time for the February Field Notes newsletter.
This year, I worked with growers and consultants on a handful of pests. Weed management is always top-of-mind for rice growers. There are limited practices and products that can control problematic weeds, and in some circumstances, the weeds may develop resistance to the herbicides that are available. If herbicide resistance is suspected, please contact me so that we can submit weed seeds for testing. We would collect the seeds in the late summer or early fall when they have matured but have not shattered. Resistance testing is overseen by UC Weed Science Extension Specialist, Kassim Al-Khatib, and takes place in greenhouses during the winter. By the following spring, we provide the grower with information on which herbicides are still working and which are not.
Over the last several years, I have conducted trials to evaluate the efficacy of a new herbicide product, Loyant (florpyrauxifen-benzyl; Corteva Agriscience), on grasses and sedges in the Delta drill-seeded system. (See https://ucanr.edu/sites/deltacrops/files/361256.pdf for project reports.) Loyant is now registered and will be available for the 2023 season. This year, I collaborated with graduate student, Deniz Inci, and Kassim Al-Khatib to evaluate product efficacy on cattails. With only one year of data, we cannot make too many conclusions, but it appeared that Loyant had efficacy on small cattails (less than three feet tall, Figure 1). The results were promising, and we will continue our investigation next year to see what more we can learn.
I have been trapping armyworms in the Delta since 2016 (Figure 2), in collaboration with fellow farm advisor, Luis Espino. The traps catch true armyworm moths. They were deployed on three ranches and monitored weekly. In 2022, we recovered the highest moth counts since 2017, and the peak flight occurred about one week earlier than in 2017. This is important information for management because, based on the armyworm life cycle, we know that peak worm populations occur approximately two weeks after peak moth flight. In other words, growers can make informed decisions based on the monitoring data and adapt their management to the field conditions. Trap monitoring is one part of an integrated pest management program for armyworms, which also includes scouting for feeding damage and the worms themselves. Over the years, I have observed armyworms in riparian and wetland vegetation that neighbor rice fields, so it is important to scout those areas, too. More information about Delta armyworm trapping is available on my website (https://ucanr.edu/sites/deltacrops/Rice/Armyworms/).
I observed a couple important diseases this year – stem rot and rice blast. In recent years, we have observed stem rot on certain ranches at harvest. As fields were getting drained, the plants turned brown instead of golden, and grains hadn't filled (Figure 3). We developed post-harvest straw management programs that included burying the residue to try to break down the fungal inoculum. This year, we noticed the problem in some locations early enough to make treatment decisions. We walked the fields at late-tillering and early-heading and found black lesions on the stems at the water line (Figure 4). We submitted samples to UC Plant Pathology Extension Specialist, Cassandra Swett, and confirmed stem rot. Treatment timing is critical for managing stem rot, and treatment at early-heading has been observed to be most effective. There is a tendency for stem rot to be more severe on low potassium soils, and many Delta soils are naturally low in potassium. A potassium fertility program may help mitigate disease severity, but management should include a multi-pronged approach that also includes post-harvest straw management and possibly fungicide applications. Currently, there is no varietal resistance to the disease. The rice blast that was confirmed was in one field. We observed lesions below the panicle (“neck blast”) that caused blanking. Blast spores can move by air, are favored by warm, wet conditions, and can be exacerbated by excess nitrogen. Fungicides are registered and are most effective at early-heading. For more information on both of these diseases, see the fact sheets written by Luis Espino (https://rice.ucanr.edu/FactSheets/Rice/), or give me a call.
We should continue to keep weedy rice on our radars because we have seen it in the Delta in the past. Where we have observed light infestations, it appears that keen management – including in-season rogueing, post-harvest management that includes straw chopping but not incorporation, and winter flooding – can reduce, if not eliminate the pest. These are our management tools until a herbicide is approved for spot-spraying. Growers should also pay attention to equipment sanitation – harvesting weedy rice fields last (if possible) and thoroughly cleaning out equipment after harvesting fields where weedy rice has been observed.
Finally, I will be starting new projects this winter, in collaboration with fellow farm advisor, Whitney Brim-DeForest, and graduate student, Sara Rosenberg, to evaluate winter cover cropping between rice crops. Our objectives are to evaluate carbon and nitrogen cycling and variety survivability during the cool, wet (we hope!) winter conditions. These projects are supported by the CDFA Healthy Soils Program and the CA Rice Research Board. I look forward to sharing results in the years to come.
I am grateful to work with a great team of UC colleagues on these rice projects. I am also grateful for all the growers who have collaborated with us. I wish everyone a good end to the year, and I look forward to working with you again in 2023.
* * *
Michelle Leinfelder-Miles is the UC Cooperative Extension Delta Crops Resource Management Advisor serving San Joaquin, Contra Costa, Sacramento, Solano, and Yolo counties.
Original source: Rice Notes -- November 2022 newsletter
- Author: Michelle Leinfelder-Miles
- Posted by: Gale Perez
From the San Joaquin Valley Delta Field Crops blog • Jan. 21, 2021
Michelle Leinfelder-Miles is the UC Cooperative Extension Delta Crops Resource Management Advisor serving San Joaquin, Sacramento, Yolo, Solano, and Contra Costa counties.
******
Herbicide Trial in Delta Drill-Seeded Rice - 2020
Weeds are important pests of California rice systems, and weed management can account for roughly 17 percent of total operating costs (Espino et al., 2016). Integrated weed management uses cultural and chemical practices where herbicide are important tools. Certain conditions in California rice production systems, however, increase the likelihood of developing herbicide resistance. Herbicide resistance is the ability of certain weed biotypes to survive certain herbicide treatments when the weed species is usually killed by that herbicide (Al-Khatib et al., 2019). Such conditions include, but are not limited to, lack of crop rotation, the efficacy of certain herbicides on certain weeds causing them to get frequently used, and not having diverse chemistries available.
In 2019 and 2020, trials were conducted to evaluate the efficacy of a new herbicide product called Loyant (florpyrauxifen-benzyl; group 4 herbicide; Corteva Agriscience) in drill-seeded rice in the Delta region. Loyant is registered in rice growing states in the southern US but would be a new chemistry in California. Corteva Agriscience expects to have CA registration in time for the 2021 use season. The objective of the trials, by assessing different rates and treatment combinations, was to understand the efficacy and crop tolerance of Loyant for weed control in drill-seeded rice in California. This article will describe select results of the 2020 trial. Treatments are listed in Table 1. Complete information from both years is available from the attached pdf file below: Herbicide Trials in Delta Drill-Seeded Rice – 2019 and 2020.
Weed control. Overall weed pressure was relatively low, observing about 1 weed per square foot in an untreated strip next to the trial. The prominent weeds in the field were Echinochloa species (i.e. watergrass, barnyardgrass; Figure 1). We did not have a completely untreated control but instead considered the pre-emergent only treatment (i.e. Prowl) the control. There was a trend for the Prowl treatment to have the highest weed counts. The treatments that had the best weed control were the grower standard and Loyant/SuperWham herbicide programs (Table 2).
- We found no differences in yield, but there was a trend for the grower standard and the Loyant/SuperWham herbicide programs to have slightly higher yields (Table 3, below). Measured yields were uncharacteristically high for the region. Our explanation of the data is that we did our hand harvest in the early morning hours when there was a heavy dew. Because variability across the replicates was low, as indicated by the coefficient of variation, we believe the data demonstrate relative comparability of herbicide programs, even though the absolute values are high.
- The purpose of the trial was to learn the efficacy and crop tolerance of Loyant (florpyrauxifen-benzyl) for weed control in California drill-seeded rice. We observed Loyant to have good activity on watergrass and barnyardgrass, which were the predominant weeds in the trial. We observed Loyant treatments to have similarly low weed counts compared to the grower standard, and a Loyant/SuperWham herbicide program appears to provide comparable weed control to the grower standard. The results demonstrate that Loyant could be used in drill-seeded rice herbicide programs, providing a different chemistry for herbicide resistance management.
The aforementioned information on products and practices is for educational purposes only and does not constitute an endorsement or recommendation by the University of California.
Herbicide Trials in Delta Drill-Seeded Rice – 2019 and 2020
- Author: Michelle Leinfelder-Miles
June 1 through June 9, 2019 is California Invasive Species Action Week. According to the CA Department of Fish and Wildlife (CDFW), the purpose of CA Invasive Species Action Week is to “increase public awareness of invasive species issues and promote public participation in the fight against California's invasive species and their impacts on our natural resources.” CDFW describes prevention as the most important action toward managing invasive species. Invasive species negatively impact our resources, including water and native plants and animals, but they also impact our way of life, including agriculture, recreation, our economy, and human health.
As of May 22, 2019, 510 nutria have been taken in California, most in Merced County. They have also been detected in Stanislaus, San Joaquin, Fresno, Tuolumne, and Mariposa counties. In the San Joaquin County Delta, nutria were found near the City of Lathrop in 2018; however, in May 2019, one nutria was detected at Rough and Ready Island in Stockton, indicating that they have moved north.
Unlike other rodents found in the Delta – like muskrats, otters, and beavers – nutria are not native. (Hence, I'm highlighting them during Invasive Species Action Week!) Adult body size is about 2 feet in length, tail length is about 1 foot, and weight is approximately 10-20 pounds. They have partially webbed back feet, which they use to propel themselves in water. They have white whiskers and often have orange teeth. They are primarily active at night.
CDFW is working to eradicate nutria, and you can help in their efforts. Please report sightings by calling 866-440-9530, or by emailing invasives@wildlife.ca.gov. Land owners may take nutria by legal means to protect crops and property, and it is illegal to import, transport, or possess them in California. More information about reporting sightings, eradication efforts, takings, and identification (including photographs) is available from the CDFW website. It is important that we work together to prevent the expansion of this or other invasive pests in California.
- Author: Michelle Leinfelder-Miles
The 2017 season was marked by weather extremes, including record winter rainfall and high summer temperatures. Despite those, Delta rice growers generally observed an average to above-average season. Total acreage for the Delta south of the Yolo Bypass was roughly 2900 acres. For some growers, acreage was up because they were able to get ground preparation done early, but for others, acreage was down because the ground was late to dry out. Most of the Delta acreage is in San Joaquin County, with a few hundred acres in the “tail” of Sacramento County. The acreage was entirely drill-seeded, as is typical for the Delta, and planted with M.206.
Annual rainfall (October 1, 2016 to September 30, 2017) for the region varied greatly by location. CIMIS stations for the south Delta reported rainfall from 16 to 20 inches, but stations in the north Delta reported 28 to 38 inches. Most of this rainfall fell in October through January. Spring rainfall lingered into the month of April, but accumulation of at least a tenth of an inch ceased by mid-April. Given the high organic matter content of many Delta soils, fields generally dried out for on-schedule planting in late-April through early-May, with few exceptions.
Cooler temperatures in the Delta, compared to the Sacramento Valley, make the Delta a challenging place to grow rice. The summer of 2017, however, brought many days over 100⁰F. This varied greatly by location, with some areas in the north Delta having approximately 10 days over 100⁰F and areas of the south Delta having 25 days over 100⁰F, according to CIMIS stations. Hot days meant warmer nights, which was a good thing for Delta rice culture. Delta rice can experience blanking due to low night-time temperatures, influenced by Delta breezes. We expect blanking to occur when the developing pollen grains are exposed to night-time temperatures at or below 55⁰ F for several hours. Across four Delta CIMIS stations, the average minimum temperature from August 1st to September 15th was 60⁰F.
Harvest was generally on-schedule and occurred from late-September to early-October. Anecdotally, yields were up and averaged over 90 cwt/acre. Growers suspect that the higher summer temperatures (including higher night-time temperatures) resulted in less blanking and higher yields.
Overall, Delta rice growers had an average to above-average year as we close out 2017. Let's hope for a similar 2018.
- Author: Ben Faber
So, every few weeks the question comes up of whether to install soil moisture meters which leads to the question of which to buy and install or have installed. And then come the questions of what do the readings mean and why aren't the readings consistent. Or maybe this question arrives after the grower has installed the sensors or system and the values don't conform to a known or knowable pattern.
The first question to the grower is why they want to install soil moisture sensors or a system. Everyone has a different answer which I've always found interesting. Usually it boils down to having more or better information, although it's hard to beat a good old soil auger. Which takes time and labor.
So once that is cleared up, it comes down to what area they want to monitor. Is it an acre, 10 acres, 50 acres, 100 acres, 200 acres, 1,000 etc.? What are the different irrigation blocks, soil types, aspects? How complex is the area that is to be monitored? Do they need one monitoring site or many? Can the information be gathered in the field, or does it need to be accessed from a distance? Linked by hardwire, infrared, cell phone, wifi, satellite, etc.?
Then the question is does the grower do the installation or is it done by a company? And then whatever the case is, who maintains the system and for that matter, who maintains the information? What software is used and who interprets it?
And what sensors are being used: tension, electrical resistance, conductance, capacitance, electromagnetic…….? The list seems to go on and there are no models and brands coming out on a regular basis. And how reliable are the sensors? What's their lifespan? And what are they measuring and in what units? How affected are the readings by salinity and what soil volume are they measuring? And how important is their placement?
This last point is so often overlooked. The sensor needs to be in the active root zone where water is being taken up. Not where it's convenient to read, not where the plants cant use the water. Placement is so often overlooked.
And then how much do you want to spend? $100 per installation, $1000? With a monthly or yearly maintenance fee or none? Who responds when there are problems?
Wow, so yeah, there are lots of questions. Here's a chart that might help categorize some of the questions:
Method |
Cost |
Ease of use |
Accuracy |
Reliability |
Salt-affected |
Stationary |
Gypsum block |
L |
H |
H |
H |
L |
YES |
Tensiometer |
L |
M |
H |
M |
L |
YES |
Portable tensiometer |
M |
M |
H |
M |
L |
NO |
Solid-state tensiometer |
M |
H |
H |
H |
L |
YES |
Time domain reflectometer |
H |
M |
H |
H |
M |
BOTH |
Neutron probe |
H |
L |
H |
H |
L |
YES |
Feel (soil probe) |
L |
H |
H |
H |
L |
NO |
Gravimetric (oven) |
L |
M |
H |
H |
L |
NO |
Conductance |
L |
H |
M |
M |
H |
BOTH |
Capacitance |
M |
H |
M |
H |
M |
BOTH |
H, high; M, medium; L, low
And the good Almond Doctor might help some more:
http://thealmonddoctor.com/2015/07/10/soil-moisture-sensing-systems/
And maybe some of these publications can help sort out what questions to ask
http://calag.ucanr.edu/Archive/?article=ca.v054n03p38
http://calag.ucanr.edu/Archive/?article=ca.v054n03p47
http://anrcatalog.ucanr.edu/Details.aspx?itemNo=21635
Khaled Bali, our Irrigation Specialist at Kearney Research and Education Center near Fresno, is part of a group in the process of evaluating different types and models of soil moisture sensors. He should have a publication that can more accurately sort through the many sensor choices that are available at this time. But in time, there should be more models on the market and new update will be necessary.
The question, though, is to ask yourself how irrigation is being done and how it can be improved. The basics of design, maintenance, distribution uniformity and how scheduling is being currently done – when and how much to apply. Definitely, soil moisture sensors can help, but you gotta know how to use them and maintain them, just like the whole irrigation system.
A grower who uses tensiometers told me that people think of soil sensors as though they were reading a book. Something cut and dried. A simple plot line that you follow. Irrigation is not a book. There are many other subplots to irrigation than just reading the digital face. Looking at the weather, evapotranspiration, the tree, how fast the moisture is depleted, how deep the moisture is being pulled from all contribute to the "sensors" used to irrigate. Use them all. Even though this grower has irrigators on 250 acres of trees, he also checks the orchard tensiometers at least once a week on his own to confirm all of his senses.