SUMMARY

The goal of this project is to increase the adoption of grapevine red blotch disease (GRBD) management practices at the individual and regional scale. To accomplish the goal, this outreach project supported and empowered viticulture specialists with the educational resources and technical skills to advocate for adoption of practices within their organizations and when attempting collective action with neighboring vineyards. During the first project year, we conducted a needs assessment (survey; interviews) with those involved in the technical aspects of grape growing (“viticulture specialists”). We used the resulting information to generate tailored, durable multimedia educational materials to help viticulture specialists communicate GRBD knowledge, better understand how practices are adopted, and successfully advocate for action. We developed and delivered technical workshops for viticulture specialists, focusing on skills development to initiate conversations about GRBD, engage in collective action with neighboring vineyards to reach breakthrough collaborative decisions, advocate for science-based decisions, and communicate the science of RBD to non-technical audiences. The workshops and educational resources are currently being deployed in Napa County, and will be condensed and generalized, with resources made widely available through our online presence, personal interactions, and professional networks. Project activities are being assessed using pre- and post- workshop quantitative surveys and follow-up interviews to determine the impact on collaboration, quality of decision-making on GRBD, and adoption of management practices.

A webpage called Grape Varieties in the USA (https://grapevarieties.info) was developed with original information on some raisin, table, wine, and multi-use grapes. The website contains original descriptions, pictures, and data of various varieties, listed in alphabetical order of their variety names. Varieties can also be sorted by certain key attributes with the aid of pull-down menus. Sorting is additive, so one or more attributes can be used in a given search. Users can also select from keywords that variety description authors or editors have assigned to each variety, and there is also a search window in which users can supply their own search terms. By mid-January there were 20 article descriptions published on the site, written by four different authors, and several other descriptions are in preparation. Raisin varieties include all commercially significant Thompson-type raisin grapes currently grown in the USA. Table varieties include all those suggested by the California Table Grape Commission. Wine varieties include some of the best performing Vitis vinifera varieties from trials conducted at the Kearney Agricultural Center, and disease-resistant varieties contributed from colleagues in southern states. Descriptions in preparation include other lesser-known wine varieties that performed well in California variety trials.

By the end of the extended 2019-2020 funding cycle, we produced the five On the Road educational events originally proposed in the 2019 AVF Extension and Outreach proposal. Due to the COVID-19 pandemic, we applied for and received a No Cost Extension to complete the programs proposed for 2019-2020 by April 15, 2021. We actually completed all of the remaining programs (Lodi, Napa, Stanislaus, and Paso Robles (Temecula was completed in Nov 2019)) virtually, in December 2020 (proposal 2019-1685). So, we completed all of the proposed events for the 2019-2020 funding cycle (proposed in 2019), and we expect to complete all of the events proposed in 2020 before the end of April 2021 (proposal 2020-1685).

The first On the Road event in the previous (2019-2020) grant cycle took place in Temecula at the Wilson Creek Winery, on November 18, 2019. Unfortunately, due to COVID-19, only the Temecula event was held in person (see the 2020 Annual Report for details). The second program was originally scheduled to take place at the Grape Festival Grounds in Lodi on March 17, 2020. It ended up as a virtual OTR program on July 13, 2020. Forty people attended live and sixty viewed the recorded program online. The third program was scheduled to take place on March 31, 2020, at COPIA in Napa, and it ended up as a virtual program taking place on, July 15 and 16, 2020. The first day’s program had 100 live attendees and the second day had 96 attending live. Interestingly, only 25 viewed the recordings. The fourth 2019-2020 OTR program was organized with Kari Arnold and was originally scheduled to occur on April 8, 2020, at Harvest Hall in Stanislaus County. This program was also provided virtually on July 27, 2020. Forty-eight people attended the Zoom meeting live and 41 viewed the recording. The fifth and final program proposed in 2019 (UCD V and E On the Road in Paso Robles) took place on December 10, 2020, and had 120 people attending live! An additional 145 people viewed the recording online. Overall, we reached 759 individuals just through our 2019-2020 On the Road programs.

We plan to complete the four On the Road (OTR) events, proposed in January 2020, before the end of April 2021. The first of the four events will be a virtual program for Merced, Mariposa, and Madera Counties on February 22, 2021. We worked with Karl Lund (3Ms Viticulture Advisor) to determine topics and speakers of interest. Confirmed speakers: Kendra Baumgartner, Anita Oberholster, Kent Daane, Akif Eskalen, George Zhuang, and Helen Dahlke. The second event will take place virtually on March 16, 2021. We worked with Kamyar Aram, the Alameda and Contra Costa Counties Specialty Crops Advisor (including wine grapes), to determine speakers of interest. Confirmed Speakers: Anita Oberholster, Megan Bartlett, Mason Earles, Andrew McElrone, and Andrew Walker. The third OTR program in March/April 2021, in Kern County, is currently under development with the new Viticulture Advisor, Tian Tian. The fourth program of 2021 will also take place in the March/April 2021 timeframe. We are currently discussing topics and dates with a member of the Shasta Cascade Viticulture Association to determine relevant topics and dates for the program. We also organized fourteen virtual, one-hour “Office Hours with Dave and Anita” extension programs. Researchers in specific areas gave short summaries (20 min) of what is known about the topic and the research performed to date. We then opened up the Zoom meeting to questions from attendees.

By the end of the 2018-2019 funding cycle, we produced the four On the Road educational events (San Diego, Monterey, Lake, and Tulare) proposed in the 2018 AVF Extension and Outreach grant. We substituted Tulare for the originally proposed Kern County program due to the departure of the Farm Advisor, Ashraf El-Kereamy. In addition, we have completed one of the proposed events for the 2019-2020 funding cycle (proposed in 2019), and we expect to complete all of the proposed events before the end of the grant period (April 15, 2020).

The first On the Road event in the current (2019-2020) grant cycle took place in Temecula at the Wilson Creek Winery, on November 18, 2019. To determine the most relevant topics to present, we worked closely with Carmen Gispert, Viticulture Farm Advisor for Riverside, San Diego, and San Bernardino counties. This program was initially proposed as an experiment to bring an On Campus, theme-based, continuing education program to a region far from the Davis campus. We had several discussions with Carmen and in the end, we brought topics she thought would be of interest to her stakeholders (a traditional On the Road program). Anita Oberholster gave two talks,
one focused on cleaning and sanitation and the other covered smoke exposure. We introduced Mason Earles (AI and viticulture) and Megan Bartlett (Improving Grapevine water-use efficiency and drought tolerance), two of our new faculty members. David Block spoke about Phenolic Extraction and Wine Quality and Johann Martinez (Kurtural Lab) spoke about the Effects of Irrigation, Shade Nets, and Crop Load on Grape Composition and Wine Quality. We were excited to have such a great turnout, with 80 growers and vintners attending.

We plan to complete four more On the Road events (for a total of five) before the end of the current funding cycle. The first of the four events is scheduled to take place in San Joaquin County at Burgundy Hall in Lodi on March 17, 2020. We worked with Stephanie Bolton (Lodi Winegrape Commission), to determine topics and speakers of interest. Confirmed speakers include Anita Oberholster, Megan Bartlett, Elisabeth Forrestel, Mason Earles, David Block, and Ben Montpetit. The second event is scheduled on March 31, 2020, in Napa at COPIA. We worked with the Napa Valley Vintners to determine speakers of interest, which include: Anita Oberholster, Megan
Bartlett, Elisabeth Forrestel, Mason Earles, David Block, Andrew Waterhouse, and Ben Montpetit. The third (of the four left to complete) On the Road program is scheduled for April 8, 2020, in Stanislaus County in Harvest Hall. We are working with Kari Arnold, the local farm advisor, to determine topics and speakers. The fourth program of 2020 and fifth overall is scheduled to take place in San Luis Obispo County. We are currently looking at March 19 or April 9, 2020 as favorable dates and have discussed topics with Mark Battany. Other extension efforts include organizing this year’s On Campus programs while we go through the process of hiring an event
logistics person.

1. Summary: “Formation of a Mealybug Biocontrol Research Focus Group for Crush District 11”

by PI Dr. Stephanie Bolton, Lodi Winegrape Commission

The project has successfully met its objectives as stated during the period of March 2017 –

April 2018. The Lodi Mealybug Biocontrol Research Focus Group met monthly at a local diner

to discuss vine mealybug biocontrol, researching topics such as which beneficial insects are

present and effective in our area, current grower perceptions of beneficial insects and mealybugs,

the likelihood of neighbor cooperation in vine mealybug management, ant control, Movento,

organic options for mealybugs, and other topics related to vine mealybug biocontrol and

management. The Focus Group became a center of learning and exploration where scientists,

extension personnel, growers, pest control advisors, and the industry opened communication

around the subject of mealybug biocontrol in efforts to develop real-world, applicable outreach

materials and events which would propel our local winegrape industry forward and decrease our

risk for further leafroll virus infections.

Through the conversations and learning experienced during the Focus Group monthly meetings,

along with information gathered via expert consultants and educational field trips, a strategy for

mealybug biocontrol in Crush District 11 was established. This simple strategy is:

1. Don’t kill the good insects.
2. Control the ants.
3. Use pheromone mating disruption.

In Lodi, we are still generally in phase 1 where we are teaching growers how to keep their

beneficial insects alive through distribution of an easy-to-read chart based upon UC IPM

guidelines and local experience (available at lodigrowers.com). In August 2017 at a Mealybug ID

Field Day, about 120 growers had a fun time learning how to identify mealybugs which have been parasitized by the Anagyrus wasp, one of the two main biocontrol agents in our region. During the April 2018 Mealybug & Virus Outreach Meeting, about 150 growers learned the significant

role of ants in the vine mealybug and leafroll virus story. The Focus Group has planned ant bait

experiments for 2018 after finding that there is no economical, efficient ant control method

available for large acres of vineyards. While pheromone mating disruption is being used with

success in our region to decrease mealybug populations and to attract beneficial insects, it is still

cost-prohibitive for many growers. Growers were given mealybug traps donated by Suterra at the

April 2018 meeting, which they will bring back in May 2018 for a follow-up Mealybug Trap

Workshop. Thus, they are learning whether the male mealybug is present in their field and how

to use the traps, which is the first step towards neighborhood coordinated pheromone mating

disruption.

By taking the time to fully assess the current mealybug biocontrol management options in the

region and to learn more about the pathogen itself, future priorities for more targeted research on

a larger scale were best determined. Priorities include but are not limited to: discovering an

efficient and cost-effective ant control method for large acreage in Crush District 11, learning how to release Cryptolaemus beetles in our vineyards, and learning how to eliminate underground vine mealybugs following a leafroll virus infected vineyard rip-out.