Delta Region Areawide Aquatic Weed Project

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nutria where you can observe its long, rat-like tail

Update on Nutria Populations

April 20, 2026
By Sarah Marsh Janish
Last year during the 2025 Winter Grower Meetings, we mentioned nutria as an emerging invasive pest capable of harming rice fields, especially in the Delta region. After these meetings, we received several anecdotal confirmations of sightings of nutria and nutria burrows around the Stockton area and further…
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Stem Rot Monitoring Guidelines for the Mid Boot Stage

April 13, 2026
By Luis A Espino
Stem rot is a common rice pathogen present in all fields. The pathogen produces resting structures called sclerotia that survive in the soil after harvest. The sclerotia germinate in the spring and the pathogen infects tillers at the water level approximately when plants reach panicle initiation (45 to 50…
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AI generated buff tadpole shrimp weight lifting pesticides

From Highly Effective to Highly Resistant: Pyrethroids and Tadpole Shrimp in Rice

April 6, 2026
By Ian M Grettenberger, Luis A Espino
Additional authors: Sophie Allen, UCD Jr. SpecialistPyrethroids are heavily relied upon for management of tadpole shrimp in California rice. Their efficacy has historically been excellent (and mostly still is!); they have proven both effective and very economical given their low material costs, in particular…
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Weed Management Considerations for Drill-Seeded No-Till Rice

March 30, 2026
By Whitney B Brim-Deforest
Interest in drill-seeded no-till rice has increased in recent years; however, the most comprehensive herbicide research in drill-seeded rice systems was conducted before 2015, more than 10 years ago. Transitioning from water-seeded to drill-seeded rice, whether tilled or no-till, substantially alters weed…
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Statewide Variety Trial Results

March 23, 2026
By Bruce A Linquist
The California Rice Research Board supports our statewide variety trail evaluation each year. This project runs nine variety trails around the state and evaluates commercially available lines as well as promising lines that are coming out of the Rice Experiment Station. These are large trails with each one…
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2025 Year-in Review

March 16, 2026
By Bruce A Linquist
In California, 533,000 acres of rice were planted in 2025, which is the highest amount since 2016. Some of this increase in acreage was seen in San Joaquin County which planted 15,000 acres in 2025. There has been a steady increase in acreage in this county since 2017 when only 3000 acres were planted. …
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whitewater fire flowers versus redstem flowers

White Water Fire Weed Morphology and Control in California Rice

March 9, 2026
By Consuelo B Baez Vega
Authors: Robinson Johnson, Deniz Inci, Kassim Al-KhatibDepartment of Plant Sciences, University of California, Davis Background White Water Fire (Bergia capensis L.) is an annual broadleaf weed native to southern China, tropical Asia, and Africa, which was recently reported in a California rice…
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2026 Rice Production Workshop Scheduled in Richvale

March 2, 2026
By Consuelo B Baez Vega
Contact: UCCE Sutter–Yuba142A Garden HighwayYuba City, CA 95991Phone: (530) 822-7515Email: wbrimdeforest@ucanr.edu RICHVALE, CA — Rice growers and agricultural professionals from across the Sacramento Valley are invited to attend the 2026 Rice Production Workshop, a two-day educational program…
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Seed Production Update

March 2, 2026
By Consuelo B Baez Vega
Author: Timothy Blank, Director of Seed Certification Operations, California Crop Improvement Association (CCIA)~28,500 acres were inspected by the California Crop Improvement Association in 2025, of which 25,783 acres were eligible for seed production. Of the eligible acres harvested for seed, 1117 were…
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2025 Delta Rice Recap

February 23, 2026
By Michelle M Leinfelder-Miles
This article is my annual review of UCCE Delta rice research and seasonal observations.Variety Trial: Delta rice acreage has been steadily increasing, and yields are comparable with the statewide average (Table 1). I estimate that Delta acreage approached, if not exceeded, 15,000 acres in 2025. To…
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Weedy Rice Survey Update

February 16, 2026
By Troy L Clark, Luis A Espino, Whitney B Brim-Deforest
We have conducted field surveys of weedy rice in 2020 and 2025. The objectives were to document the location of weedy rice infestations, determine how severe these infestations are, and evaluate the spread of this weed. In 2020, we inspected 15,748 acres of rice. Of these, 3,412 acres (21% of surveyed…
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Save the Date!

February 12, 2026
By Taiyu Guan
2026 Propanil Stewardship Meeting"Propanil Stewardship & Alternative Watergrass Management Strategies"Dates: February 26 (Thursday), 2026 Time: 10:00 am - 12:00 pmLocation: CIP Conference Room, 100 Sunrise Blvd., Colusa, CA<Agenda>
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hedgerow site 2025 demonstration

Fall Update: Rice Field Research Projects in the Sacramento Valley

February 9, 2026
By Whitney B Brim-Deforest, Sarah Marsh Janish, Luis A Espino
It has been a busy year! Here is a quick recap of some of our studies.Hedgerows: This study, initiated in 2024, is evaluating how planting rows of native species along permanent levees can influence beneficial insect activity in rice fields as well as weed pressure on levees in rice systems. Preliminary data…
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WarAgainstWeeds podcast

Broomrape podcast interview

February 4, 2026
By Brad Hanson
Some of my weed science extension colleagues in the midwest have a podcast called War Against Weeds  supported with funding from the North Central IPM Center.  I was interviewed on the podcast a few years ago about herbicide resistant weeds in orchards.  Earlier this week, they invited me back…
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American pondweed with emerged inflorescences. Submerged or floating-leaved aquatic plants with roots within the soil sediment.

UCCE Sutter-Yuba Advisors to Participate in Weed Management Area Project

January 30, 2026
By Whitney B Brim-Deforest, Troy L Clark
UCCE Sutter–Yuba is pleased to announce the launch of a new collaborative project with the Sutter and Yuba County Agricultural Commissioners’ Offices focused on the identification and management of invasive weed species in the region. As part of this effort, this project will be coordinating ongoing mapping…
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Upcoming Winter Grower Meetings

January 12, 2026
By Sarah Marsh Janish
2026 Rice Winter Grower Meetings CE Credits: 2 DPR (0.5 L&R, 0.5 Aerial, 1 Other) & CCA Pending Wednesday, Jan 21Richvale: 8:00 AM @ Evangelical Church (5219 Church St)Willows: 1:00 PM @ Willows Memorial Hall (525 W Sycamore St)Thursday, Jan 22Colusa: 8:00 AM @ CIP Conference…
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Save the Date!

October 29, 2025
By Taiyu Guan
IPM Rice Workgroup Meeting: Drip Irrigated Rice and Tomato RotationsAll are welcome! We are soliciting feedback, experiences, and opinions about rotating rice with tomatoes, with a focus on drip-irrigating rice. Lunch will be included. Please Click Here for the Registration Form! Date:…
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Fig. 6. Adoption of herbicide spot application (A) and herbicide spray line outside the mulch line/tree rows (B) in a conventional walnut orchard site where walnut leaf mulch was implemented for weed management.

Response of Walnut Leaf Mulch for Weed Management

September 22, 2025
By Clebson G Goncalves
     The use of walnut leaf biomass as a natural mulch and an eco-friendly practice can help prevent weed seed germination by excluding light and/or acting as a physical barrier that prevents weed emergence. Beyond that, several studies have shown potential allelopathic effects of juglone and…
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Welcome

Participants
NASA Ames Research Center
USDA-ARS Invasive Species and Pollinator Health Research Unit 
California Dept of Parks & Recreation - Division of Boating & Waterways
California Dept of Food & Agriculture
Sacramento-San Joaquin Delta Conservancy
University of California, Davis
Local mosquito vector control districts
 
General areas of study
Weed mapping tools
Management techniques and strategies
Weed effects on ecosystems, native plants, and water quality
Biological control agents
Effects of weeds on mosquito populations
Bio-economic modeling of weed control costs and project benefits

 

Announcements

As of September 2021, a special issue of the Journal of Aquatic Plant Management features participants in DRAAWP. Individual papers can be seen under the "Journal Articles" tab to the left.

We have posted a new 2020 Areawide Report under the Products tab to the left.

This year's Aquatic Plant Management Society annual meeting is planned for July 12-14, 2021, in New Orleans.

The Western Aquatic Plant Management Society (WAPMS) recently participated in a virtual conference jointly with the Western Society of Weed Science. The 40th annual meeting of WAPMS is scheduled for March 7-11, 2022. 

Our DRAAWP informational brochure is available from the Site Navigation tab at the left.

 

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