winegrape harvest
Photo: Yakov Oskanov / Shutterstock.com

Press Release by California Association of Winegrape Growers

In July the Pierce’s Disease / Glassy Winged Sharpshooter Board (PD/GWSS Board) voted to set the grower assessment rate in support of the Pierce’s Disease Control Program (Program) at $1.25 per $1,000 of crop value for the 2022 harvest. This assessment provides vital funding for research on GWSS and other designated vineyard pests and for research on developing crop resistance to PD.

“CAWG fully supports this important program and we thank growers for their funding of the program,” said Tom Slater, Chair of the California Association of Winegrape Growers. “Inflation has increased costs of every aspect of our industry which includes research and costs of the Pierce’s Disease Control Program. CAWG appreciates the volunteer work of the PD/GWSS Board members, who represent the industry. Their due diligence, including choosing to invest in a science audit, helps contain costs and assure our assessment dollars are spent wisely.”

“Wine Institute commends the Pierce’s Disease and Glassy-winged Sharpshooter Board and staff for their decades of work to protect California’s vineyards from invasive pests and diseases,” said Robert P. Koch, President & CEO of Wine Institute. “This commitment to research will continue to provide significant benefits to our wine communities.”

In considering the 2022 rate adjustment, the PD/GWSS Board sought sufficient funds to support testing of clean plant material at UC Davis and an audit by the National Academy of Sciences (NAS). NAS will create an interdisciplinary committee to assess the current struggles facing the California wine grape industry in controlling grapevine viruses, with a specific focus on Grapevine red blotch virus and Grapevine leafroll associated virus type 3.

The committee will review the current and recent research activities of the PD/GWSS Board, and help direct a future funding approach to address the knowledge and management gaps required to minimize the spread of, and economic losses due to these viruses. The committee will also identify ways in which the PD/GWSS Board can draw from a wider breadth of researchers and utilize cutting edge genetic tools and platforms to combat these virus problems.

Over the 21-year history of the program, the assessment has ranged from a high of $3.00 in 2001 to a low of $0.75 in 2015. The average annual harvest assessment is $1.40. The assessment was $1.00 for the 2019, 2020, and 2021 harvests. The 2022 harvest assessment will provide an estimated $3.5 million in funding.

Since 2019, the PD/GWSS Board has committed more than $11 million to research that benefits vineyard health. Below are a few examples of the outcomes of that research:

Discovery of potential biological control of PD using Paraburkholderia phytofirmans by Steven Lindow at UC Berkeley. The Board funded a new project this year at UC Davis to assess efficacy and compare with other biological control PD control tools, with the goal to produce data that would help directly lead to commercialization.

The recent successful laboratory use and publication of CRISPR/Cas9 genetic technology in GWSS through work at UC Riverside, which has the potential to revolutionize PD vector control by making GWSS unable to vector PD.

Improved understanding of the effects of grapevine red blotch on vine physiology and wine composition through recent work at UC Davis.

Improved understanding and communication of research-based control measures for Pierce’s disease as well as Board-designated viral diseases (red blotch, leafroll and fan leaf) through work at UC Cooperative Extension, Cornell University, and UC Berkeley.

The Program has also had great success in treatment of GWSS in rural, suburban and urban settings. This includes nursery treatments, area wide management and the ongoing treatment for GWSS in residential Vacaville.

A recent study led at UC Cooperative Extension, Kern County, found that Program-led efforts in area-wide management of GWSS in the southern San Joaquin Valley have been a success and a good model for disease control.