- Author: Whitney Brim-DeForest
- Author: Roberta Firoved
The labeled weeds that RebelEX®controls are sprangletop, watergrass (both early and late), barnyardgrass, ricefield bulrush, Monochoria, redstem, ducksalad, California arrowhead, and water plantain. It does not have a water-holding period. The application timing begins from when the rice has one leaf or more, up to 60 days before harvest. Efficacy, as with most products, is better when the weeds are smaller. For flooded fields, it is important to have maximum contact, so it is recommended to lower the water in the field until at least 70% of the weed biomass is exposed, before application.
The product is “rainfast” (meaning it isn't affected by water) within 2 hours, so reflooding quickly is recommended. The label recommends restarting the flood at 3 hours after application, and to have the field completely reflooded within 24 to 48 hours at a maximum. Long drainage periods can encourage additional germination of certain weed species, including smallflower umbrella sedge, watergrass, barnyardgrass, and sprangletop.
Since RebelEX® also contains penoxsulam, it cannot be applied in the same season as Granite GR® or Granite SC®. Doing so will cause significant phytotoxicity to the rice, and will likely impact yields. Clincher® can be applied in the same season, but depending on the rate of RebelEX® applied, the Clincher® application rates will vary, so please refer to the label for rates and timings if planning to also apply both herbicides in the same season. For management of resistance, however, it is not recommended to apply Clincher® and RebelEx® in the same season, as both contain the same active ingredient, cyhalofop. Repeated applications of the same active ingredient (cyhalofop) will select for resistance in sprangletop, barnyardgrass, and watergrass (both late and early).
Remember to always follow all label instructions when applying any pesticide, as the label is the law. Make sure to pay particular attention to the Use Precautions and Restrictions. Consult your local Agricultural Commissioner's Office regarding buffer zones and aerial restrictions, before making any applications.
Label and SDS: https://www.corteva.us/products-and-solutions/crop-protection/rebelex-ca.html
- Author: Bruce Linquist
Following my blog post about a week ago about using urea or aqua-ammonia (aqua), a number of people have been asking to see the data. The study was conducted in 2017 at the Rice Experiment Station. Aqua and liquid urea were applied at three rates (50, 100 and 150 lb N/ac). Both N fertilizers were injected into the soil at 3 to 4 inches depth. Treatments were replicated three times. Across the N treatments, yields were similar between the aqua and liquid urea treatments. Yields were low, but overall state-wide yields in 2017 were low as well. In other studies (data not shown), we used dry urea banded into dry soil before flooding to the same depth as aqua we saw almost identical yields across seven on-farm studies. Based on these data, liquid or dry urea that is injected or buried into a dry soil before flooding, performs the same as aqua.
- Author: Bruce Linquist
This morning I was out with several members of our research team on the northwest side of the valley planting a variety trial. The grower we were working with had just finished planting all of his rice acreage (1200 ac) yesterday (April 30). Pretty amazing how fast the rice is getting in this year. I know the west side is often earlier than the rest of the valley; however, growers around the valley are moving much faster this year. By the end of next week, we will likely have all of our variety trials (we have seven this year) planted. We have accomplished this so early before.
This is a good start to the season! Generally, when we plant early, yields tend to be higher. This is clear from the figure below. This figure shows state-wide yield averages from 1994 to 2019 relative to the date when 50% of the rice acreage had been planted (based on USDA data). One reason for higher yields is that dry springs (which allow for early planting dates), also give growers time to prepare their seedbed exactly how they want to without skipping passes. From the UCCE Rice Yield Contest, we have seen that good and uniform stand establishment is a key for high yields. Realizing, that the yield potential may be higher this year, the N fertilizer requirement may be a bit higher. It will be important to access the crop midseason (around PI) to see if the crop may need more N fertilizer to realize its potential. This can be done with either a Leaf Color Chart or the Green Seeker.
The UCCE Rice Yield Contest (http://rice.ucanr.edu/Rice_Yield_Contest/) will be running again this year and we look forward to your participation and learning more about how to achieve high yields. The 2020 forms will be available soon. You will need to enter the contest by the Annual Rice Field Day in late August.
- Author: Whitney Brim-DeForest
The impetus behind the weed survey is due to the increasing numbers of new weed species that have appeared in the past several years: winged primrose-willow, weedy rice, monochoria, and recently, one (possibly two) new watergrass species. We are hoping that by conducting a survey, we may find some new species before they spread, and better establish ranges for the species we know we have.
A crew of two people will be stopping in random fields in the major rice-producing counties. We will take soil samples from the top six inches of soil in each field. The soil samples will then be processed in a greenhouse at UC Davis, where the weeds will be grown out to identify each species present in the soil. The reason we are surveying this way, instead of surveying during the rice-growing season, is due to the use of herbicides during the season, we would have difficulty seeing the presence of weed species that are well-controlled by the herbicides.
- Author: Whitney Brim-DeForest
The 2019 Rice Weed Course will take place:
Friday, September 6, 2019
from 8:00AM to 4:10PM (Registration begins at 7:30AM)
at the
Hamilton Road Field (on West Hamilton Rd. between Hwy. 99 & Riceton Hwy.)
and Rice Experiment Station, Biggs, CA
This year will mark the third rice-specific weed course at the Hamilton Road Field and the Rice Experiment Station in Biggs, CA on Friday, Sept. 6, 2019. The day will begin with an interactive field tour of the research plots (Hamilton Road Field) where attendees can get up close to the weeds and rice (bring your boots!) The course will include a hands-on weed identification session on emerging and mature weeds. In the afternoon, speakers will address several pertinent topics in CA rice, including algae, weedy rice, regulatory update, best management for grasses, and how to construct a weed management program. This course is a great opportunity to interact directly with the UCCE and UC Davis Rice Weed Research Team!
For a full agenda and registration go to:
https://wric.ucdavis.edu/events/rice_weed_course_2019.html
For questions, please contact Whitney Brim-DeForest at 530-822-7515, or by email at wbrimdeforest@ucanr.edu
Credits for PCA, QAC, QAL, Private Applicator: 6.0 other, 0.5 laws
CA Certified Crop Adviser: 6.0 IPM