Considerations for choosing the right medium grain rice variety

                        With planting season coming up, thinking about appropriate variety selection is key, and one of the first steps towards ensuring a good 2021 crop. Each year the California Rice Research Board funds a statewide variety trial testing program. Here I summarize some of that data.

   

       

Map showing     variety trial locations in the Sacramento Valley. Dot color refers to nighttime     temperatures in the last half of July (during booting). Red dots refer show     locations where cold nighttime temperatures are not normally a concern for     blanking. Yellow dots are those locations where cold temperatures more     common, and the blue dot location is where cold temperatures occur almost     every year. Temperatures are a concern when they drop below 58oF.

These trails are on grower managed fields in eight locations around the Sacramento Valley as seen in the map. One major difference in the locations selected is nighttime temperatures in mid to late July when most of the rice is booting. Cold temperatures during this period can cause blanking and lower yields. On the map, locations in red are where cold nighttime temperatures are usually not a problem. These locations are generally north of highway 20. In yellow are locations where growers need to be concerned about low nighttime temperatures; while they may not occur every year, they are common. In blue (South Yolo) is a location where cold temperatures occur almost every year. Importantly, in each of these regions may be micro-climates where temperatures vary from the “average”.

Some varieties are more tolerant of cold than others. Therefore, it is important to select varieties that are suitable for the location you are farming. In the tables below, are yield data from the past five years for each location in the variety trial. Only the main medium grains varieties are shown (M-105, M-206, M-209, M-210 and M-211). This data will allow for a more informed decision when it comes to variety selection.

The warmer locations are north of Hwy 20,in Glenn, Butte and Colusa counties. At these locations, M-211 consistently outperforms the other medium grains by 4 cwt/ac, on average, over the five years and four locations. Among the other varieties shown, there were no consistent differences among them.

In the cooler locations, M-209 performed the worst in general. In the moderately cool locations (yellow dots on the map), M-105 and M-211 both did consistently well. In the coldest location (South Yolo), M 105 performed the best; while M-209 and M-211 performed poorly. Both M-209 and M-211 have similar days to maturity (about 5-7 days later than M-206). This data suggest that M-211 may have a broader adaptability range than M-209 becasue it appears to be slightly more cold tolerant. However, in the coolest location even M-211 did not perform well.

M-206 versus M-210: M-206 has beenthe most broadly adaptable variety available. While it may not always be the highest yielder, it generally does well across all locations. M-210 is a new variety which has blast resistance. It is basically M-206 with genes for blast resistance and has similar time to heading. Based on these data M-206 and M-210 have almost identical yields in both the warm and cooler regions.

Thoughts on M-211: As seen in the data provided, M-211 is a tremendously promising variety in terms of yield potential. Furthermore, its sensory qualities are similar to premium grain varieties such as M-401. However, one draw back is that for good milling quality, M-211 needs to be harvested at 20-22% moisture. Harvesting below this moisture can result in low milling quality. Given this, it may not be a variety that is suitable for large acreage planting and this should be tested by growers.

 

 

 

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 nature.

We came up with a preliminary set of characteristics to distinguish this unknown biotype or species (we are unsure if it is a distinct species) from the typical barnyardgrass and late watergrass found in California rice fields. All were characterized by their seed size and awns (Table 1).

Table 1. Preliminary distinguishing characteristics of watergrass species in California rice fields, based on seed characteristics. 

Preliminary Identification	Seed Description
Late watergrass	Large size, no awns
Early watergrass	Large size, awned (all seeds)
Barnyardgrass	Small size, variably awned (some seeds have awns, some do not)
New biotype/species (unknown)	Small size, awned (all seeds)

In 2018, we collected 8 samples from the field, and used two late watergrass samples from known susceptible populations to use as controls. We conducted a screening in the greenhouse, to see if we could replicate what we were seeing in the field. Field rates of Cerano® (clomazone), Butte® (benzobicyclon+halosulfuron), Granite GR® (penoxsulam), and Bolero® (thiobencarb) were used as the early-season granular applications. Field rates of SuperWham® (propanil), Regiment® (bispyribac-sodium) and Clincher® (cyhalofop) were used to test for the late-season cleanup applications. In the greenhouse, all applications were made at the 1.5 leaf stage of the grass.

Results indicate that 8 of the 8 samples were not controlled (less than 50% by biomass, in comparison to the untreated controls) by Granite GR® or Butte®. 7 of the 8 samples were not controlled by Bolero®, and 6 of the 8 were not controlled by Cerano®. This closely follows what growers were stating had occurred in the field: the watergrass was escaping early-season control, and was then difficult or impossible to control with later-season herbicide applications. SuperWham®, Regiment®, and Clincher® controlled 8 of 8 samples (at least 60% control). However, since the greenhouse application was conducted at an early timing (1.5 leaf stage), it is possible that later applications in the field may be less effective.

For growers, the implications of this preliminary screening are that control of this new biotype/species will need to be prioritized early in the season. Possible treatments (keep in mind that these have not been field-tested and could cause phytotoxicity) could be: a stale seedbed using a non-selective herbicide; pre-plant Abolish® (thiobencarb) followed by Cerano® or Butte® or Granite GR®; Cerano® followed by Butte® or Bolero® or Granite GR®; or Butte® followed by Granite GR® or Bolero®. There is still a strong likelihood that a follow-up application may still be required later in the season, even with these early-season applications.

In 2020, more than 60 watergrass samples were collected from all over the rice-growing region. We will continue working on identification and conduct further herbicide screening this year. 

SUPPRESS® herbicide EC, a product manufactured by Westbridge Agricultural Products, was registered in California in 2015. Its active ingredients are Caprylic Acid and Capric Acid. It is registered for use in organic production, and it is labeled for use in “agricultural food and non-food crops”. In rice, it can be utilized only when the field is drained (no standing water allowed).

Since 2019, UCCE Rice Advisor Whitney Brim-DeForest has been testing SUPPRESS® herbicide for use in weed control in rice. In 2019, she collaborated with Jim Cook (Colusa County Farm Supply), to spot spray weedy rice in a field containing Type 3 (long awns, straw hulled). The application was made with a handheld backpack sprayer, at the highest labeled rate. The timing was too close to heading, however, and some of the weedy rice plants recovered.

This past season, in 2020, we did further testing in the field, on several different weedy rice types (field was a mix of Types 1, 2, 3, and 5). The application timing for the field testing in 2020 was made with a handheld backpack sprayer, at the highest labeled rate. The timing was approximately at panicle initiation, and at two weeks after application, the weedy rice plants were 100% controlled. At harvest, there was some regrowth, but none of the plants produced viable panicles.

For use in weedy rice spot spraying in 2021, SUPPRESS® could be an option, but the label does not allow for application when there is standing water in the field. Therefore, in order to be used, the field will need to be drained before application. Application timing is after the last grass herbicide has been applied, but before the weedy rice has started to flower (generally no earlier than 60 days after seeding). Reflooding is recommended within 48 hours of application to reduce the germination of additional weeds, unless the field can remain drained until harvest.

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: https://westbridge.com/products-pdf-documents/SUPPRESS_Herbicide_Label_161109.pdf

SDS: https://westbridge.com/products-pdf-documents/SUPPRESS_Herbicide_SDS_2015.pdf

For more information, contact UCCE Rice Advisor, Whitney Brim-DeForest (wbrimdeforest@ucanr.edu), and Roberta Firoved, Industry Affairs Manager for the California Rice Commission (rfiroved@calrice.org) 

University of California Cooperative Extension Sutter-Yuba-Colusa is holding a series of webinars in September and October to provide research updates on some of the major crops in the Sacramento Valley. The classes are relevant to growers throughout California and are primarily focused on pest management and pesticide safety. 

The September 9th webinar will feature Franz Niederholzer, Orchard Systems Advisor. "We will be reviewing proven almond IPM practices with an eye to reducing input costs, where possible, while delivering effective pest control," says Niederholzer. He has been working in almonds in the Sacramento Valley for almost 20 years. 

Amber Vinchesi-Vahl, Vegetable Crops Advisor, will give her webinar on September 16th. She states, "I will be providing information on important pest issues in vegetables and the latest research updates on disease and weed management in processing tomatoes and cucumber beetles in melons." Her research on tomatoes covers cultivator trials for within-row weed control and monitoring of soilborne fungal pathogens.

Whitney Brim-DeForest, Rice and Wild Rice Advisor, will present September 30th. "The webinar will provide an opportunity for discussion and interaction about weed identification," she says. "We will also cover the latest research updates on specific weed species, resistance management, and new herbicides in rice." The information is relevant to both organic and conventional rice growers, so all are encouraged to attend.

The final webinar will take place on October 7, and will be given by Sarah Light, Agronomy Advisor. Light says, "We will cover opportunities to decrease environmental risk through pesticide selection and application, accurate diagnosis, and reduction of loss to the environment." 

Enrollment is limited, so register early. The cost is $20 for 1, $35 for 2, $50 for 3, and $60 for 4 webinars. For more details or to register, visit http://ucanr.edu/syc-uccevirtualwebinars. DPR CE credits have been approved (4 "other" hours total, 1 per class), and CCA credits have been approved for IPM credits (4 hours total, 1 per class).  

If you have questions, contact Whitney Brim-DeForest [wbrimdeforest@ucanr.edu or call the UCCE Sutter-Yuba office at (530) 822-7515].