- Author: Luis Espino
I recently visited a couple of fields that were showing signs of sulfide toxicity. At first sight, the symptoms could be confused with blast. Plants dry out and turn brown, panicles blank out. However, plants affected by sulfide won't have any leaf or neck blast lesions. But the tell sign that sulfide toxicity is the issue are the roots. Affected plants will have black roots that smell like rotten eggs.
Sulfide toxicity occurs in patches, most likely, where organic matter accumulated and water flow is limited.
Roots of plants affected by sulfide turn black and smell like rotten eggs.
Sulfide toxicity happens when soil microbes use sulfate as energy source, and produce hidrogen sulfide as a by product. Normally, the sulfide will precipitate and won't accumulate, but in certain soils sulfide can accumulate and become toxic to the plant. Sulfide toxicity seems to be caused by accumulation of organic matter, such as straw or root balls, that do not decompose completely during the winter time. Irrigation water with high salt content can aggravate the problem, especially in areas where water movement is limited.
Aerating the soil stops the accumulation of sulfide, therefore, draining for harvest will stop the problem.
- Author: Whitney Brim-DeForest
It's that time again! If you would like to submit seeds for herbicide resistance testing, many weed species will be maturing right about now.
The UCCE Rice Weeds Program tests grower submitted seed samples of potentially herbicide-resistant watergrass species, sprangletop, smallflower umbrella sedge and bulrush. However, we encourage you to submit ANY species that you suspect to be resistant. We keep individual grower information confidential and any reporting of results will not identify individual growers.
Please fill out the form (linked here) for each weed seed sample (each field and/or species). The following tips will ensure that you receive the best possible results:
- The best timing of collection is when the seed easily falls off the seed head by gentle agitation in a paper bag (see video for demonstration):
o For watergrass species, this should be close to rice harvest (seeds should be brownish in color)
o For sprangletop, timing will be earlier, in August or September (seeds will appear greenish)
o For the sedges, timing may be as early as July, all the way through early September
o Smallflower umbrella sedge seed is yellow, with brown hulls (looks like dust)
o Bulrush (roughseed) seeds are black and have small hairs
- Seed should be collected from areas that you know have been sprayed with the suspected herbicide.
- Collect seeds from multiple plants, and the amount should be at least a few handfuls of seed, to ensure sufficient quantity for testing.
- Please do not collect seed from around field margins.
- Allow seed to dry in the paper bag to prevent molding.
Bring the sample and form to your local UCCE Farm Advisor (Whitney, Luis, or Michelle) or send or drop off samples at the Rice Experiment Station (RES) in Biggs. If you need assistance in collection, please contact your Farm Advisor or PCA. Results should be emailed to you in March of 2021.
- Author: Whitney Brim-DeForest
The project was funded by the California Rice Research Board, and is led by Whitney Brim-DeForest (UCCE Sutter-Yuba) and Marie Jasieniuk (UC Davis).
We are reaching out to ask for locations of rice fields from growers and PCA's, so our team can go out and collect seed. We are looking for all types of watergrass: "mimic", early watergrass, late watergrass, barnyardgrass (Figure 1), and the new species that we started seeing a couple of years ago (Figure 2). We hope to start collecting in the next week or two, through the end of September.
For more information, and if you are interested in having us come out and sample your field(s), please contact Whitney Brim-DeForest (wbrimdeforest@ucanr.edu), or call 530-822-7515.
- Author: Whitney Brim-DeForest
This field day is open to the public. Please share broadly to those who may be interested in attending.
UCANR California Rice Virtual Field Day
When: August 26, 2020, 1:00-3:00 PM
Where: Online Zoom Webinar
Host: Whitney Brim DeForest, UC ANR County Director, Sutter-Yuba Counties and CE Rice and Wild Rice Advisor
Registration: $20.00
Objectives/goals: The UC Cooperative Extension and California Rice Research Station will update attendees in the areas of variety development, disease and arthropod management, weed control, weedy rice, and fertility.
The full agenda can be viewed here.
Who should attend: California rice growers, Pest Control Advisers, and others interested in California rice production systems.
Continuing education units: Applied for 1 CEU from the California Department of Pesticide Regulation (DPR) and applied for 1 CEU from Certified Crop Adviser (CCA)
Featured speakers:
- Russell Rasmussen, Associate Director, California Rice Experiment Station, California Cooperative Rice Research Foundation
- Bruce Linquist, CE Specialist, Dept. of Plant Sciences, UC Davis
- Kassim Al-Khatib, CE Specialist, Dept. of Plant Sciences, UC Davis
- Whitney Brim-DeForest, CE Rice and Wild Rice Advisor & County Director, Sutter-Yuba Counties
- Luis Espino, CE Rice Farming Systems Advisor & County Director, Butte County
- Ian Grettenberger, CE Assistant Specialist, Dept. of Entomology, UC Davis
- Michelle Leinfelder-Miles, CE Farm Advisor, San Joaquin County
Contacts for more information:
- Logistics and registration: Rachel Palmer, ANR Program Support Unit, (530) 750-1361
- Course content:Whitney Brim-DeForest, UC ANR County Director, Sutter-Yuba Counties and CE Rice and Wild Rice Advisor
This field day is open to the public. Please share broadly to those who may be interested in attending.
THIS EVENT WILL BE RECORDED FOR EDUCATIONAL OR PROMOTIONAL USE BY THE UNIVERSITY OF CALIFORNIA. CONTACT THE ORGANIZERS OF THIS EVENT FOR MORE INFORMATION.
- Author: Luis Espino
I have been getting quite a few questions regarding blast, mostly from Glenn and Colusa counties. It seems that 2020 will be a year with significant blast pressure.
Under California conditions, blast can be observed in fields before heading. This occurrence is referred to as leaf blast. Later, when panicles emerge, blast can infect the node right below the panicle, causing panicle blanking. This is referred to as panicle blast. Blast can also affect other nodes in the plant, causing lodging and panicle blanking as well.
Leaf blast |
Neck blast |
Node blast |
The fungicides azoxystrobin and trifloxystrobin (the active ingredients in Quadris and Stratego, respectively), are labeled for blast control. In general, treatments for leaf blast are not recommended. Leaf blast should be viewed as a sign that the panicles need to be protected with a fungicide application at early heading.
One question I frequently get is weather treatment of leaf blast will help reduce the severity of panicle blast later on. Unfortunately, I do not have an answer. The fungicides we use to manage blast inhibit spore germination. By spraying for leaf blast, the spore pressure in the field would be reduced. However, infections that occurred before the fungicide was applied will continue their cycle and will produce more spores. Additionally, blast spores are moved by air currents, and can come from neighboring fields.
In a trial conduced in 2019, application of Quadris or Stratego at maximum label rates at the mid boot stage (4-inch panicle inside the boot) resulted in a 85% reduction in the number of blasted panicles, while application at 100% heading resulted in 60% reduction in the number of blasted panicles. In this trial, the heading treatment was applied a little too late, resulting in less efficacy than the mid boot treatment. Application early at 35 days after seeding had no significant effect on blast.
If you are seeing more leaf blast than previous years, a good strategy would be to do a fungicide application at the mid-boot to boot split stage, and a second application at 50% heading. If economics only allow for one application, shoot for early heading, when 20-50% of the panicles have emerged from the boot. Remember that even if you don't see leaf blast, neck blast can still develop in the field if blast is in the area.
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