Weeds are important pests of California rice systems, and weed management can account for roughly 17 percent of total operating costs, according to a UC cost of production study. Integrated weed management uses cultural and chemical practices and considers the following:

• Prevention (e.g. using certified seed, equipment sanitation, maintaining roads and levees)
• Cultural practices (e.g. land leveling, crop rotation, tillage, winter flooding, drill-seeding)
• Fertilizer placement and management
• Water management
• Monitoring
• Herbicides

Herbicides are important tools; however, resistance can occur when products are not rotated, or when diverse chemistries are not available.

In 2019, in cooperation with Corteva Agriscience, I conducted a trial to evaluate the efficacy of a new herbicide product called Loyant (florpyrauxifen-benzyl). Loyant is registered in rice growing states in the southern US but would be a new chemistry in California. Corteva Agriscience anticipates California rice registration in 2020, with the product being available for use in 2021. Previous trials have shown that Loyant provides good control of broadleaf weeds (e.g. ducksalad, redstems), smallflower umbrella sedge, and ricefield bulrush. It has some activity on Echinochloa species (e.g. barnyardgrass, watergrass). More data was needed, however, in drill-seeded systems. The objective of the trial was to assess the efficacy and crop tolerance of Loyant for weed control in drill-seeded rice in California.

The trial took place in the Delta region on a Kingile muck soil. This soil classification is characterized as having upwards of 40 percent organic matter in the top foot of soil. On high organic matter soils in the Delta, the typical practice is drill-seeding. Water-seeding, which is the typical practice in the Sacramento Valley, is not successful in the Delta because the soil particles can float and move too easily, causing seed to get buried too deeply and germinate poorly.

For a full report on this trial with methods and crop injury data tables, please see my website. Treatments are described in Table 1 below. We observed slight to noticeable leaf curling in the Loyant treatments at 14 days after treatment (DAT), but this had disappeared by 21 DAT. We observed no stunting or stand reduction with any of the treatments; nor did we observe any differences in heading. All treatments had similar weed control with the exception of the Prowl-only treatment, which had statistically higher weed counts. Loyant does not control sprangletop, so sprangletop was the weed most commonly observed. We found no differences in yield or seed moisture at harvest (Table 2 below), and we observed no lodging. Yield averaged 8965 pounds per acre across treatments, and seed moisture averaged 13.7 percent.

In summary, the purpose of this trial was to learn the efficacy and crop tolerance of Loyant (florpyrauxifen-benzyl) for weed control in drill-seeded rice. We observed slight leaf rolling with the Loyant treatments a couple weeks after treatment, but those symptoms were gone by the third week after treatment. We observed Loyant to have good activity on the Echinochloa species but not on sprangletop, which was expected based on previous company trials. We observed Loyant treatments to have similarly low weed counts compared to the grower standard practice, and no significant differences in yield among the treatments. Tank mixes will be needed to manage sprangletop. The results indicate that Loyant could be used in drill-seeded rice herbicide programs, providing a different chemistry for herbicide resistance management.

This information on products and practices is for educational purposes only and does not constitute an endorsement or recommendation by the University of California.

 

Table 1. Rice herbicide treatments.

Happy New Year! We are entering "meeting season". The new year brings several opportunities for continuing education.  

1. UC Cooperative Extension will host the SJC and Delta Field Crops Meeting on Friday, January 10, 2020 from 8:00am to 12:00pm. The meeting location is the Cabral Agricultural Center in Stockton (2101 E. Earhart Ave., Stockton, CA 95206). Please see this previous post for the agenda, or open the attachment below. We will offer continuing education credits for DPR licensing (2), CCA certification (3.5), and nitrogen management (1.5). Light refreshments will be provided.

2. UC Cooperative Extension will host five meetings for rice growers. The meeting details are as follows:

Richvale:     Monday, Jan. 13, 8:30am, Evangelical Church, 5219 Church St., Richvale

Willows:      Monday, Jan. 13, 1:30pm, Glenn Co. Office of Education, 311 South Villa Ave., Willows

Colusa:       Tuesday, Jan. 14, 8:30am, Colusa Casino Resort, 3770 Hwy. 45, Colusa

Yuba City:   Tuesday, Jan. 14, 1:30pm, Veterans Hall, 1425 Veterans Memorial Circle, Yuba City

Woodland:   Wednesday, Jan. 15, 1:30pm, Norton Hall, 70 Cottonwood St., Woodland

Doors open at 8:00am, and meetings start at 8:30am at Richvale, Colusa, and Woodland. Doors open at 1:00pm, and meetings start at 1:30pm at Willows and Yuba City. DPR and CCA continuing education credits will be offered. For the program, please visit the UC Rice Blog.

3. San Joaquin County Farm Bureau and the Ag Commissioner's Office will host Spray Safe on January 27, 2020. The event takes place at the Cabral Agricultural Center in Stockton. Registration begins at 7:30am, with lunch concluding at 12:50pm. Please see the registration flyer and agenda here. 

4. The California Chapter of the American Society of Agronomy will hold its annual Plant and Soil Conference on February 4-5 in Fresno, California. Program information and registration are available from the conference website. Session topics include nitrogen management, drip irrigation, and cover cropping, among others. DPR licensing, CCA certification, and nitrogen management continuing education credits will be offered.

UCCE farm advisors will be hosting local meetings for other crops, like tomatoes, almonds, and cherries. Please see our calendar for details.

UC Cooperative Extension will host the SJC and Delta Field Crops Meeting on Friday, January 10, 2020 from 8:00am to 12:00pm. The meeting location is the Cabral Agricultural Center in Stockton (2101 E. Earhart Ave., Stockton, CA 95206). Coffee and refreshments will be provided.

A printable version of the agenda is attached at the bottom of this post. The agenda is as follows:

8:15am     Delta Rice Update: Armyworms, Herbicide Trial, Weedy Rice, Michelle Leinfelder-Miles, UCCE San Joaquin/Delta Counties

8:45am     Regulatory Update, Tim Pelican, San Joaquin County Agricultural Commissioner

9:00am     Alfalfa Weevil Insecticide Resistance, Madison Hendrick, UC Davis

9:15am     Benefits of Alfalfa in Crop Rotations, Nicole Tautges, UC Davis

9:45am     IPM in Organic Field and Vegetable Crop Production, Rachael Long, UCCE Yolo/Sacramento/Solano Counties

10:15am   Break

10:30am   Observations and Pest Issues with CBD Hemp Experiments in California, Dan Putnam, UC Davis

11:00am   Fertilizing Corn and Wheat with Manure: Research Results, Nick Clark, UCCE Fresno/Tulare/Kings Counties

11:30am   Warm-Season Legume Cover Cropping in the Delta, Michelle Leinfelder-Miles, UCCE, San Joaquin/Delta Counties

12:00pm   Evaluations and Adjourn

We have submitted applications for continuing education for pesticide licensing and certified crop advisors. We have also submitted an application for nitrogen management continuing education, which would help to satisfy growers' continuing education requirement for the Irrigated Lands Program. Applications are pending.

Our programs are open to all potential participants. If you require special accommodations, please contact UCCE San Joaquin County at 209-953-6100. I wish you a happy holiday season, and I hope to see you at the meeting in the new year.

The results of the 2019 UCCE Delta field corn variety trial (Fig. 1), located on Tyler Island, are presented in Table 1. Three replicate blocks of fourteen varieties were planted on May 7th by air planter. The fourteen varieties included 11 varieties submitted by seed companies and three submitted by the grower. All varieties were glyphosate tolerant. Each plot consisted of four 30-inch beds on an average row length of 1300 feet. Seed was planted approximately two inches deep and six inches apart down the row. The soil is a Rindge mucky silt loam with approximately 20 percent organic matter in the top 15 inches of soil. The Rindge series is a mucky peat soil down to about 60 inches, and approximately 55,600 acres in the Delta are described by the Rindge classification. The previous crop in the field was corn. Subsurface irrigation by “spud ditch” was employed twice. Anhydrous ammonia was applied pre-plant (115 units N/acre), and 8-24-6 with ½ percent of zinc was knifed in at planting (additional 33 units N/acre). Weed control was by cultivation and glyphosate herbicide program, and Onager miticide was applied. The field was harvested on October 21^st.

Stand counts were made approximately two weeks after planting. The stand was assessed in the center two rows of each four-row plot, counting the plants along a 10-foot length. Bloom was assessed over the week of July 15^th. We monitored disease incidence and plant lodging in late September. Disease incidence, particularly Fusarium ear rot, was lower in 2019 compared to 2018. A sign of Fusarium ear rot is white fungal mycelium around the kernels. The disease is usually introduced to the ears by corn earworm or by thrips that travel down the corn silks at pollination. Incidence may be reduced in varieties with longer or tighter husks that prevent insect infestations. Planting earlier in the season may also reduce incidence, as the crop may reach pollination before insect pests are prevalent. Head smut, a disease that replaces ears with dark brown spores, had low incidence this year. These two diseases are generally managed by variety selection.

The table presents mean values for the three replicates. The statistical method used to compare the means is called the Tukey's range test. Varieties were considered statistically different if their P value was less than 0.05, or 5 percent. What this means is that when differences between varieties exist, we are 95% certain that the two varieties are actually different; the results are not due to random chance. Differences between varieties are indicated by different letters following the mean. For example, a variety that has only the letter “a” after the mean yield value is different from a variety that is followed by only the letter “b”, but it is not different from a variety whose mean value is followed by both letters (“ab”). Similarly, a variety whose mean yield is followed by the letters “ab” is not different from a variety whose mean yield is followed by the letters “bc”. Eight varieties have a letter “a” following their mean yield, which means that those eight varieties all performed similarly in the trial. In other words, based on this research, we cannot attribute numerical differences to varietal differences.

In addition to yield, there were also statistical differences among varieties in days to bloom, Fusarium ear rot, head smut, ear height, grain moisture, and bushelweight. The CV, or coefficient of variation, is the standard deviation divided by the mean, or a measure of variability in relation to the mean. For the diseases, the variability among the three replicates was very high.

For a printable version of this report, please see: https://ucanr.edu/sites/deltacrops/Corn/. Special thanks go to the cooperating growers, Gary and Steve Mello, and the participating seed companies.