- Author: Whitney Brim-DeForest
- Editor: Taiyu Guan
- Editor: Consuelo B Baez Vega
“White Water Fire” (Bergia capensis)
The sample was collected from a rice field and was found growing inside the field. It was not growing on banks or in ditches, it appears the preferable habitat is rice fields and marshy areas. It looks similar to; redstem (Ammania spp.) but the stem itself is much larger in diameter and less dense. Currently, there is little information globally on the plant; how invasive it is and how it impacts rice fields. The plant is native to Africa and China, and has been identified in parts of Central America.Since the initial identification, the Butte County Department of Agriculture has surveyed additional rice fields and did not find it in any other locations. One of the common ways of spread is the cultivation of rice. As of this date it has only been found in three checks of one rice site.
As with all noxious weed species, in commercial agricultural settings it is important to follow best management practices, this may include roguing field of species prior to harvest and cleaning/sanitizing of equipment post-harvest.
As more information is gained from partners at CDFA, the County Agricultural Commissioner's office will disseminate information to all interested parties.
From UCCE: Kassim Al-Khatib is currently working on developing information for herbicide control of this weed (using currently registered rice herbicides). An update will be forthcoming at the winter grower meetings. Stay tuned!
Winged Primrose Willow (Ludwigia decurrens)
Winged primrose willow (WPW) is rated a Category A pest by the California Department of Food and Agriculture (CDFA), meaning that it is subject to enforcement action if found in a field. Its presence in a seed field also disqualifies that field from seed production. It was first found in Butte County rice fields in 2011. Since then, it is not known to have spread into other counties, but it is still found along major irrigation canals and thus has the potential to move.
It starts flowering in July or August, so the big, yellow flowers should be easy to spot if you have it in your field. It tends to grow in drained areas, or along field margins (levees, irrigation ditches, etc.) The seed pods, roots, and stems can float, so until it is eradicated, there is a chance that it could end up in other areas outside of Butte County. It propagates by seed, but parts of stems or roots can re-grow into plants.
Herbicide applications are effective when the weed is small, but will not be effective as the plants grow taller (more than 1 foot tall).
Effective herbicide applications are:
- Early water active herbicides:
- Bolero Ultramax
- Cerano
- Granite GR
- Follow-up foliar
- Early: Sandea, Londax
- Late: Grandstand or Grandstand/Propanil mix
The only means of dealing with it when it is large is by pulling it out and disposing of it. Disposal should be into a trash can, not on field edges.
Photos by Luis Espino, UCCE
To distinguish from common primrose, the WPW has 4 petals (see above photo) and the common primrose has 5 petals. Both are yellow in color. The winged primrose stem has wings on the stem (see below) in cross-section.
As always, please be on the lookout for unusual weeds, and report them to your local Farm Advisor (Michelle Leinfelder-Miles in San Joaquin, Luis Espino in Butte or Glenn, or Whitney Brim-DeForest in Sutter, Yuba, Placer or Sacramento).
- Author: Luis Espino
- Editor: Taiyu Guan
- Editor: Consuelo B Baez Vega
This year we saw severe blast in some areas of the Valley. I did not see any leaf blast during tillering and only noticed blast during heading. After talking with some growers and PCAs, it seems that this was common in several areas. I also saw and got reports of severe blast in drill or dry seeded rice. In these cases, the blast was so severe that even fungicide applications were not able to reduce the blast incidence significatively. Kernel smut was also an issue in some fields, but it did not seem to be as bad an issue as blast was. Tiller diseases were average, but I seemed to notice more aggregate sheath spot this year than previously.
Why was blast more prevalent this year? Several factors can increase the incidence of blast, but two that come to mind are excess nitrogen and relative humidity. With many fields being fallowed last year, there might have been more nitrogen in the soil available for the plant. If the rate of aqua N was not reduced, the field may have ended up with some excess nitrogen that could have made blast a problem
Fig. 1. Maximum and minimum percent relative humidity for 2022 and 2023 at the Williams CIMIS station.
Why do we see more severe blast when dry or drill-seeding? It is not clear why, but it may have to do with how blast is transmitted from residue or seed to seedling. There might be also some physiological changes in the plants that make them more susceptible.
The only blast resistant variety commercially available at this point is M-210. I did not see any blast or got any reports of blast in M-210. In areas where blast is a common occurrence, and when dry or drill-seeding, I would recommend using M-210. Variety trials from previous years have shown that M-210 yields the same as M-206. I will compare M-206 and M-210 yields from this year's variety trials and present them during our winter meetings.
Another common question I get is if azoxystrobin (the active ingredient in Quadris) is still effective against blast. I was able to set up a trail in a field in Glenn County and results showed that the most commonly used rate of Quadris (12.5 oz/a) was effective against blast (fig. 2). There could be some differences in susceptibility to the fungicide in different areas, so more trials are needed to answer this question thoroughly.
Fig. 2. Percent neck or node blast in M-206 treated with Quadris. Treatment was made at the late boot, early heading stage. Glenn County, 2023
- Editor: Consuelo B Baez Vega
Richvale: Tuesday, January 9, 8:00 am, Evangelical Church, 5219 Church St., Richvale
Willows: Tuesday, January 9, 1:00 pm, Glenn County Office of Education, 311 South Villa Avenue, Willows
Colusa: Wednesday, January 10, 8:00 am, CIP Conference Room, 100 Sunrise Blvd., Colusa
Yuba City: Wednesday, January 10, 1:00 pm, Veterans Hall, 1425 Veterans Memorial Circle, Yuba City
Woodland: Thursday, January 11, 8:00 am, Norton Hall, 70 Cottonwood St, Woodland
TIME: Doors open at 8:00 am and meetings start at 8:30 am at Woodland, Richvale, and Colusa.
Doors open at 1:00 pm and meetings start at 1:30 p, at Glenn and Yuba City.
Program
8:00am (1:00pm) Doors open, sign-in, coffee
8:30am (1:30pm) Call meeting to order
8:35am (1:35pm) Rice Research Board Nominations - Lacey Stogsdill, Rice Research Board
8:45am (1:45pm) County Agricultural Commissioner Updates
9:00am (2:00pm) Fertility Update, Bruce Linquist, UC Davis
9:20am (2:20pm) Rice Experiment Station Update, Dustin Harrell, Rice Experiment Station Director
9:40am (2:40pm) Weed Management Update, Kassim Al-Khatib, UC Davis
10:00am (3:00pm) BREAK
10:15am (3:15pm) Yield Contest - Bruce Linquist, UC Davis
10:30am (3:30pm) Invertebrate Management Update - Ian Grettenberger, UC Davis
10:50am (3:50pm) Disease Management Update, Luis Espino, UCCE
11:10am (4:10pm) Emerging Weeds - Whitney Brim-DeForest, UCCE
11:30am (4:30pm) ADJOURN
***Applied for DPR and CCA CE credits***
2024 Annual Rice Grower Meetings
- Author: Bruce Linquist
- Editor: Taiyu Guan
- Editor: Consuelo B Baez Vega
I wrote in a previous Newsletter article about some new research we are doing testing no-till drill seeded rice production. Why are we doing this? It is one way to save considerable amounts of irrigation water. We estimate that up to 0.5 ac ft/ac of water could be saved. Water savings are due to using existing soil moisture (from the winter/spring rains) and limiting the evaporation of water during the first month of the season by not having the field flooded. Other potential benefits include reduced tillage costs, the ability to plant early, and avoiding tadpole shrimp and seed midge injury. If rotating with water-seeded systems, it is also a great way to use different modes of action to address herbicide resistant weed issues.
Briefly, to recap. This study was conducted at the Rice Experiment Station and was run by Mia Godbey (graduate student) and Ray Stogsdill, with Luis and Whitney looking at pests and weeds. We tested NT drill seeding into four different seedbeds.
- Fallow stale-seedbed (FSS): field was fallowed in 2022. It was disked and leveled then. It was not flooded during the winter. No tillage was done in 2023.
- No-till. We have three strict NT treatments. Rice was grown in 2022. After harvesting (harvested to limit ruts), the straw in the field was subjected to one of three treatments:
- Chopped (NT-Chop)
- Half removed to simulate baling (NT-Remove)
- Burned (NT-Burn)
The no-till fields were all winter flooded.
At time of planting, there were a lot of winter weeds in the NT-Burn and FSS treatments (with the wet spring we got more winter weeds than normal). While we tried to get rid of them by spraying glyphosate before drilling, many were tolerant. In the NT-Chop and NT-Remove treatments there were little to no weeds. On May 2 the fields were all planted with a Great Plains no-till drill seeder (see above) at a rate of 150 lb seed/ac. After seeding, all treatments received an initial irrigation flush on May 4 and the flush was drained on May 8. We did not apply any herbicide at planting before or after the flush.
We chose this year to have the same planting date for all treatments, but the FSS and NT-Burn treatments could have been planted in mid-April. However, the treatments with straw on the surface had too much soil moisture to be able to get equipment into the field and May 2 was the earliest we could get into these fields.
We did not apply any irrigation water after the initial flush at planting until June 2 when we applied the permanent flood. The rice was at the 4-leaf stage by this time. We got a good stand in all treatments. The stand was lowest in the NT-Chop treatment but still good. The soil moisture in the NT-Burn and FSS was starting to dry out but we did not see any moisture stress. In the NT-Chop treatment, there was still a lot of moisture beneath the straw mat. The winter weeds were still present but we saw very few other weeds coming up. Just before permanent flood, we applied urea and herbicides (Prowl, Clincher and Propanil).
After the permanent flood, the plants almost doubled in height in the first few days and were well above the water line. The winter weeds persisted into the permanent flood. However, they did not appear to affect the stand of rice.
Compared to 2022, 2023 had higher relative humidity during the season (fig. 1). According to the Williams CIMIS weather station, the average maximum relative humidity for the month of July for 2022 and 2023 was 77 and 96%, respectively, while the minimums were 19 and 44%. Higher relative humidity, combined with lower wind speeds during the months of July and August probably, may have resulted in longer periods of free moisture on plant surfaces during mornings, which allows for germination of blast spores and infection of leaves and panicles. These plots were harvested with a small plot combine on September 28. Grain yields responded to various rates of N application. Yields were highest (8640 lb/ac) in rice after fallow (FSS) followed by NT-Burn and then the NT-Remove and NT-Chopped. Yields in all treatments were highest at the 175 lb N/ac N rate. While these yields were no super high, they were comparable to the maximum yields we observed in water-seeded conventional rice at the RES which was 8490 lb/ac.
We are very encouraged by these results and will be providing greater detail in our upcoming winter grower meetings. In future years we will be looking at optimizing herbicide and fertility practices as well as quantifying water savings.
- Author: Timothy Blank
- Editor: Taiyu Guan
- Editor: Consuelo B Baez Vega
Certified seed production returned to normal levels in 2023. The CA Crop Improvement Assn. passed 27,818 acres for seed. Field inspections were initiated in early August and the last inspections took place in early October.
107 acres (1 field) were rejected due to the presence of weedy red rice, and those rejected acres were within the Quality Assurance program that oversees specialty varieties that are not eligible for certification. Included in the total acres passed for seed production are 1297 acres approved within the Quality Assurance program, of which 978 seed acres were Koshihikari production.
M-206 remains the variety with the most acres of seed production, followed by M-211, M-209, M-105, and M-210. Looking at all seed production by grain size, 87% of the approved production was medium grain varieties, 11% short grain varieties, and 2% long grain varieties.
