Delta Region Areawide Aquatic Weed Project

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Upcoming Winter Grower Meetings

January 12, 2026
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
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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Brad Hanson lecturing at Weed Science School 2023

Weed Science School 2025

September 4, 2025
 Weed Science School is less than two weeks away! Join the UC Davis Weed Research and Information Center for this 2.5 day course. Learn through lectures and laboratory demonstrations at the Bowley Plant Science Teaching Facility at 1200 Extension Center Drive in Davis, CA on September 16-18, 2025.Weed…
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Weedy rice plant

Weedy Rice Survey in Progress

September 2, 2025
UCCE is currently conducting a survey of fields known to have weedy rice. The objective is to determine if the infestations have increased in the past five years, since the last survey was conducted. We are contacting growers that we know have the weed to let them know about the survey. But if you suspect…
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DPR’s New 2025 License Renewal and CE Verification Process

August 29, 2025
By Chris J McDonald
It’s that time of the year to start preparing for license and certificate renewal season for pesticide applicators with the California Department of Pesticide Regulation (DPR). Applicators should have received their renewal notice in the mail (and if not, then please contact DPR at LicenseMail@cdpr.ca.gov)…
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A warm week ahead. Do we need to be worried about chalkiness?

August 29, 2025
By Bruce A Linquist
Short answer: Not like we did in 2022. However, in the northern part of Sacramento Valley, temperatures are forecasted to be warm and chalkiness may be an issue for a sensitive variety like M-211. You can read on for more. Grain chalkiness occurs when there are high temperatures (especially at night)…
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Blast

Blast in the Valley

August 28, 2025
Yesterday (Aug 28) at the Rice Experiment Station Field Day tour I mentioned that I had not seen any blast this year (only in one location where a little patch of M-105 was planted late on purpose to see if blast would develop).Well, today I found neck blast in a commercial field in Glenn County and got a…
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Drill seeding: How deep is too deep?

August 20, 2025
By Alex Ceseski
How deep is too deep to drill rice in California? I’ll get the obvious answer out of the way first: it depends! If you’re thinking of trying out drill seeding in the future, there’s going to be a learning curve. Much like with water-seeded rice, your variety selection matters as much as the weather,…
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sprangletop

Weed Updates 2025

August 13, 2025
By Whitney B Brim-Deforest
The two most problematic species I have been seeing in grower fields this year are sprangletop and, of course, watergrass. The two require slightly different management strategies, which I will elaborate on below. One of the most important things for planning for the next year, however, is knowing if…
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2025’s cool July nights

August 12, 2025
By Bruce A Linquist
Three to four weeks ago I sent out a blog on the potential for blanking due to cool nighttime temperatures during booting. Low nighttime temperatures are a concern because blanking (floret sterility) can occur during meiosis (pollen formation) when they drop below 58 oF. Blanking can cause reduced yields…
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L decurrens

Keep an eye out for Winged Water Primrose (Ludwigia decurrens)

August 11, 2025
By Sarah Marsh Janish, Vanessa Varela, Whitney B Brim-Deforest
Floating mats of dark green leaves and bright yellow flowers is a common sight in most irrigation canals and waterways around our rice fields. For the most part, these mats are comprised of creeping waterprimrose (Ludwigia peploides) and Uruguay waterprimrose (Ludwigia hexapetala), which are prolific…
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K def leaf

Potassium deficiency

August 7, 2025
By Sarah Marsh Janish
We have posted about potassium deficiency before, but we have gotten a couple of calls and messages about this recently. When potassium is deficient, leaves start showing reddish spots on the tips. These spots can be somewhat elongated and give the impression of a narrow lesion. The lesions appear late…
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rice field with bakanae

2025 Pest Issues Update

August 6, 2025
I have seen several issues with arthropods and diseases so far this year. Here’s a quick rundown:  Bakanae: Like in previous years, there have been several fields with heavy Bakanae infections. While the number of plants infected is high, I don’t think any of those fields are going to experience a…
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blackbirds in rice field

Blackbird Damage

August 4, 2025
By Sarah Marsh Janish
 Recently, I have been getting questions about possible bird damage in early-heading rice fields. Blackbirds, primarily red-winged blackbirds, can damage rice from planting season, seedling stage, and the ripening period; however, in California, where the majority of our rice is water-seeded, typically…
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picture of Fennimore retirement June 2025

UCCE Weed Specialist Steve Fennimore retires

July 31, 2025
By Brad Hanson
Sharing a link to an article posted by the UC Davis Department of Plant Sciences recapping the 28 year career of Cooperative Extension Weed Scientist Dr. Steve Fennimore.Here's a directly link to that article: https://www.plantsciences.ucdavis.edu/news/fennimore-retirement  As a colleague of Steve…
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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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