- Author: Luis Espino
- Author: Michelle Leinfelder-Miles
Thankfully, 2022 was not a bad year for rice diseases, but it is worth mentioning a couple of observations. Overall, there was very little blast this year. In the Sacramento Valley, UCCE did not diagnose any blast in the field but did receive a couple reports of it after harvest.
Blast was identified in the San Joaquin Delta in a field of M-206. Blast in the Delta is a rare occurrence because of the cooler temperatures in the area. In fact, UCCE has only identified blast there once before. Back in 2010, one Delta field of variety M-104 was confirmed as infected with blast. Year 2010 was a bad blast year, with many fields affected across the Sacramento Valley.
Blast can infect seed, it can survive in crop residue, and its spores can move long distances. Additionally, weeds are suspected to be alternate hosts. All these factors can be sources of inoculum that can result in a blast epidemic. In seed, the mycelium of the blast fungus has been found colonizing the internal surfaces of the lemma and palea (the seed coat), the pericarp and endosperm. Unfortunately, treating the seed with bleach for bakanae does not help with the blast fungus. In general, seed is not considered a major source of blast inoculum in California. Until a few years ago, certified seed used to be tested for blast. The requirement for this test was stopped in 2018 because results were always negative. However, if during the certification inspection a seed field or a portion of a seed field is identified as infected with blast, that field or portion can be rejected. Research has shown that under water seeding, there is no seed to seedling blast transmission. Seedling transmission has been documented from infected seeds planted in soil or infected seeds that remain on the soil surface. Given that most of the acreage in California is water seeded, the risk of infected seed producing blast inoculum is low. However, in the Delta, where rice is drill seeded, the risk is higher.
While disease was low overall, we did come across another fungus that is relatively new to us. A report of possible blast in M-211 was received in late summer form a PCA in Butte County. Inspection of the field revealed only a few plants affected with symptoms that looked like collar blast (Fig. 1). Samples were submitted to the UC Davis Plant Pathology Lab, and the identification came back as Nigrospora oryzae, which causes “panicle branch rot”. Interestingly, this fungus was also identified in three Delta fields (Fig. 2), one of which also had blast. Prior to 2022, we identified this fungus from samples with symptoms similar to stem rot in 2017 and 2021, and in a field with heavy discoloration of rice panicles in 2021 (Fig. 3).
The Compendium of Rice Diseases and Pests (2018, APS Press) indicates that Nigrospora species are common and occur in senescing plant tissue, and may cause lesions in plants weakened by diseases, insects, or poor nutrition. This fungus is reported to cause an ear blight and blackening of rice kernels. These descriptions fit the symptoms mentioned above. Additionally, Nigrospora oryzae has recently been identified as the causal agent of panicle branch rot disease in China (Liu et al., 2021, Plant Disease 105 (9): 2724), a disease very similar to blast, with reported yield and quality losses.
It is not clear if this fungus is developing in tissues that are already affected by stem rot or blast, or if it is causing disease symptoms. In any case, given the information in the literature and the low frequency of observation, at this point the identification of Nigrospora oryzae from California rice samples is not cause for concern, but it does warrant vigilance from the industry. Please reach out to us in the future if you see symptoms similar to these so that we can gather more information about this fungus.
- Author: Michelle Leinfelder-Miles
(Post has been updated to add the Delta Pear Research Meeting, #4.)
I wish everyone a happy, healthy, and safe new year. Here are a few upcoming meetings to bring to your attention.
1. UC Cooperative Extension will host the SJC and Delta Field Crops Meeting this Thursday, January 12, 2023 from 8:00am to 11:30am. 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. We will offer continuing education credits for DPR licensing (2) and CCA certification (3). Light refreshments will be provided.
2. UC Cooperative Extension will host five meetings for rice growers. The meeting details are as follows:
Woodland: Monday, Jan. 23, 9:00am, Norton Hall, 70 Cottonwood St., Woodland
Richvale: Tuesday, Jan. 24, 9:00am, Evangelical Church, 5219 Church St., Richvale
Willows: Tuesday, Jan. 24, 2:00pm, Glenn Co. Office of Education, 311 South Villa Ave., Willows
Colusa: Wednesday, Jan. 25, 9:00am, CIP Conference Room, 100 Sunrise Blvd., Colusa
Yuba City: Wednesday, Jan. 25, 2:00pm, UCCE Office, 142 Garden Highway, Yuba City
Doors open at 8:30am, and meetings start at 9:00am at Woodland, Richvale, and Colusa. Doors open at 1:30pm, and meetings start at 2:00pm at Willows and Yuba City. DPR and CCA continuing education credits will be offered. The detailed agenda is available here.
3. The California Chapter of the American Society of Agronomy will hold its annual Plant and Soil Conference on February 7-8 in Fresno, California. Program information and registration are available from the conference website. The early-bird registration deadline is this Friday, January 13th. Session topics include crop and water management, cover cropping and soil management for climate-smart agriculture, and integrated pest management, among others. DPR licensing, CCA certification, and nitrogen management continuing education credits will be offered.
4. Sacramento River District Pear Research Meeting, conducted by UCCE Farm Advisor, Rachel Elkins. The agenda is attached below. The meeting will take place on Tuesday, February 7th from 10:00am to 12:30pm at the Walnut Grove Library Meeting Room (14177 N. Market Street, Walnut Grove, 95690). Please contact Rachel Elkins regarding questions on the program (707-263-6838, rbelkins@ucanr.edu), or Nancy Greilich, UCCE MCP Sacramento office (916-875-6913, cesacramento@ucanr.edu) for directions to the Walnut Grove meeting.
Please don't hesitate to reach out if you have questions about these meetings.
2023 Sacramento Delta Pear Research Meeting Agenda
- Author: Michelle Leinfelder-Miles
UC Cooperative Extension will host the SJC and Delta Field Crops Meeting on Thursday, January 12, 2023 from 8:00am to 11:30am. The meeting location is the Cabral Agricultural Center in Stockton (2101 E. Earhart Ave., Stockton, CA 95206). A printable version of the agenda is attached at the bottom of this post. The agenda is as follows:
8:00am Doors Open and Sign In
8:15am Delta Rice Pest Management Update, Michelle Leinfelder-Miles, UCCE, San Joaquin/Delta Counties
8:45am Regulatory Update, Linda Pinfold, San Joaquin County Agricultural Commissioner's Office
9:15am Compost for Soil Improvement in Alfalfa, Radomir Schmidt, UC Davis
9:45am Cover Cropping and Weed Management, Sarah Light, UCCE, Sutter/Yuba/Colusa Counties
10:15am Break
10:30am Common Chickweed Problem in California Small Grains, Nick Clark, UCCE, Kings/Tulare/Fresno Counties
11:00am Soil and Water Resources in the Delta – Drought Management Considerations, Michelle Leinfelder-Miles, UCCE, San Joaquin/Delta Counties
11:30am Evaluations and Adjourn
We have submitted applications for continuing education. Credits for pesticide licensing (DPR: 0.5 of L, 1.5 of O) have been approved. Certified crop advisor credits are pending (1.0 of SW, 1.5 of PM, 0.5 of CM).
If you require special accommodations in order to participate in this meeting, 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.
2023-1-12 Field Crops Meeting Agenda
- Author: Michelle Leinfelder-Miles
UC Cooperative Extension will provide a training on small grains nitrogen management and a webtool that can help inform recommendations. The meeting will take place on Wednesday, December 14th, from 10:00am to 12:00pm, at the SJC Cabral Agricultural Center (2101 E. Earhart Ave., Stockton, 95206). The training is primarily directed toward crop consultants, but we also welcome growers and industry members to attend. Attendance is free, but we request pre-registration using this survey because we will offer lunch. Continuing education credits will be offered (CCA and N management applications pending). The agenda is pasted below, and a downloadable version is attached. Thank you for your interest in UC Cooperative Extension programming, and we hope to see you at the training!
Agenda:
9:40 a.m. Registration, light refreshments
10:00 a.m. Welcome and Introduction
10:05 a.m. Principles of N fertilizer use in California small grains
10:15 a.m. Measuring field data pre-plant and in-season: N-rich reference zones, Soil sampling for nitrate
10:30 a.m. Soil nitrate quick test demonstration and data interpretation
10:45 a.m. Webtool example and case studies
11:00 a.m. Webtool walk through
11:40 a.m. Crop Consultant/CCA forum, survey, feedback, and discussion
12:00 p.m. Adjourn and Lunch, Please RSVP using this link
Small Grains Nitrogen Management Training Agenda
- Author: Michelle Leinfelder-Miles
In 2021, the Delta Stewardship Council, with input from a technical advisory committee, released the report Delta Adapts: Creating a Climate Resilient Future for the Sacramento-San Joaquin Delta. The report describes that flooding and water quality impacts, among others, are expected with future climate stressors and chronic changes in climate. The report is also summarized in this story map.
Since releasing the report, the Council has been working with interest groups to develop climate adaptation strategies. The agriculture community was identified as an important interest group, and a group of growers and technical service providers were convened to help identify and mobilize adaptation strategies. I have been serving on this committee as a technical service provider. In that capacity, I am advertising a survey on behalf of staff at the Delta Stewardship Council and the CA Department of Food and Agriculture who are overseeing the effort. The purpose of the survey is to identify what is needed to sustain a climate-resilient agriculture sector in the Delta. The survey aims to assesses growers' preferences and needs for different approaches to climate adaptation, including CDFA's climate smart incentive programs. Please consider filling out the survey to help inform this effort.
