- 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: Bruce Linquist
The period between panicle initiation (PI) and heading is critical with respect to grain formation. During this time, cold temperatures can result in pollen sterility as the plants go through meiosis. Pollen sterility results in blanking. Nighttime temperatures below 58 oF can result in sterility. The Figure shows the relationship between average low temperatures during booting and statewide yields. Data are from 1992 to 2018. The data represent the average low temperature for a 15-day period beginning about one week after panicle initiation to one week before heading.
Varietal selection is important to minimize blanking. Varieties such as M105 and M206 are more cold tolerant than M209, for example. However, all varieties can be negatively affected by cold temperatures during this period. One way to help minimize the damage is to raise the flood water height in the field during this time to 6-8 inches (or more). The water acts as a blanket and protects the emerging panicle from cold temperatures.
This sensitive period during booting usually occurs in July. For rice planted in mid-May, the critical period is the last two weeks of July. I realize as I write this that it may already be a bit late for many growers. However, I am looking at the forecast and seeing nighttime temperatures in the mid-50s over the next few days in areas south of highway 20.
- Author: Whitney Brim-DeForest
There are 6 so far:
- Fact Sheet #1: Nutrients in Rice Grain and Straw at Harvest
- Fact Sheet #2: Managing Potassium in Rice Fields
- Fact Sheet #3: Stem Rot and Aggregate Sheath Spot of Rice
- Fact Sheet #4: Kernel Smut of Rice
- Fact Sheet #5: Growing Season Water Use in California Rice Systems
- Fact Sheet #6: Managing Rice with Limited Water
We are continuously in the process of developing more topics, so if you have suggestions, please reach out to Luis Espino (laespino@ucanr.edu) or Whitney Brim-DeForest (wbrimdeforest@ucanr.edu).
