From the CAPCA Adviser magazine :: June 2022
Whitney Brim-DeForest is a UCCE Rice and Wild Rice Advisor for Sutter, Yuba, Sacramento, and Placer Counties; Taiyu Guan is an Assistant Specialist in UCCE Sutter-Yuba Counties; Troy Clark is a Rice Junior Specialist for UCCE Butte County.
In California rice, herbicide resistance has been documented in Echinochloa spp. since the early 2000's. Recent reports of uncontrolled grasses, as well as possible new species or biotypes have precipitated renewed...
Whitney Brim-DeForest is the UC Cooperative Extension County Director for Sutter and Yuba counties and the Rice and Wild Rice Advisor for Sutter, Yuba, Capitol Corridor MCP, Placer, and Nevada counties.
In 2020, we conducted a small screening with a set of 10 watergrass samples (collected in 2018) from across the valley, trying to see if we could get an idea of what herbicides controlled the different species/biotypes. The results from those 10 samples indicated that Clincher, propanil, and Regiment, as well as Cerano, had the best.../span>
- Author: Whitney Brim-DeForest
We are having more and more difficulties controlling watergrass over the past 20 or so years. We know that as of the early 2000s, we had found multiple-herbicide resistant late watergrass (also known as mimic), as well as multiple-herbicide resistant barnyardgrass. For early watergrass, we now have resistant biotypes (to thiobencarb), with none recorded as being multiple-herbicide resistant.
In 2017, two rice fields were identified with an unknown watergrass biotype (or species) that looked very different than the three main known species that infest California rice fields (late watergrass, early watergrass, and barnyardgrass). Both fields had...
- Author: Whitney Brim-DeForest
In 2017, I started getting reports of a watergrass biotype/species (Echinochloa spp.) that was difficult to control using our suite of herbicides registered in rice. At the time, I knew we had multiple herbicide-resistance in late watergrass (Echinochloa phyllopogon), so I initially just thought the resistant biotype was spreading, and had maybe gained resistance to additional herbicide modes of action. However, once I started visiting fields, it quickly became apparent that this was not late watergrass (phenotypically-speaking). It also did not appear to be barnyardgrass (Echinochloa crus-galli), although the Echinochloa species are notoriously difficult to identify, and phenotypically quite variable in...
The UCCE Rice Team is conducting a field survey to collect watergrass samples over the next few weeks. The samples will be grown out in the greenhouse to help us start figuring out the identification and phenotypic characteristics (how to distinguish one from another) for the watergrass species found in California rice fields. The hope is that this will give us data for developing chemical and non-chemical management plans for watergrass, similar to what we have been working on with weedy rice over the past few years.
The project was funded by the California Rice Research Board, and is led by Whitney Brim-DeForest (UCCE Sutter-Yuba) and