Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
Sep 1, 2019
Project End Date
Aug 31, 2023
Grant Year
Project Director
Oberholster, A.
Recipient Organization
DAVIS,CA 95616-8671
Performing Department
Viticulture & Enology
Non Technical Summary
Grapevine red blotch disease, caused by the virus Grapevine red blotch virus (GRBV) is an urgent problem for the $162 billion US grape industry. GRBV is a prominent disease found in the majority of grape growing regions in California and Oregon. The grape industry currently lacks best practices for detecting and preventing spread of GRBV within and among vineyards. The discovery of S. festinus as a vector of GRBV significantly increased the possibility of better understanding the epidemiology of GRBD and ultimately its management. However, GRBD spread also occurs in vineyards where S. festinus has not been found. Therefore, information on potential additional vector species in these regions is paramount. Replanted vineyards in California and Oregon have experienced reinfections and a better understanding on the prevalence of GRBV and assessment of risk factors are needed. Proposed research will address knowledge gaps involving the epidemiology of the virus as driven by studies on its vectors and determining how the disease affects grapevine performance and grape quality. The economic impact of GRBV infection on producers and nurseries will also be determined. Sustainable GRBV management strategies developed from the project will be implemented to enhance economic and social impacts and to reduce the impact on environment. This project brings together researchers, extension specialists and stakeholders from CA and OR to help solve a significant new problem facing this valuable specialty crops industry. Outreach activities will be extended to the other states and can thus impact the grape industry in the country.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Goals / Objectives
Grapevine red blotch disease, caused by the virus Grapevine red blotch virus (GRBV) is an urgent problem for the $162 billion US grape industry. This proposal aims to bridge knowledge gaps while generating strategies to manage GRBV. We intend to determine virus presence and spread in states across the US, and baseline knowledge on the risk of GRBV to wine grape production in states where acreage is increasing. Research includes studies on the role of its vector(s) in GRBV spread; economic assessment of GRBV impact on grape production, wine quality, and nurseries; as well as identification of sustainable management options. The latter will have the dual goals of reducing its spread across the US and determine its economic impact on all facets of the wine grape industry, including growers, nurseries, wineries, and state and federal regulatory agencies.Objective 1. Assess the prevalence and rate of spread of GRBV and the impact of red blotch disease on production and fruit quality in US grape production areas.Sub-objective 1.1 Determine prevalence and spread of GRBV in US grape production areas.Subobjective 1.2 Identify alternative hosts and reservoirs of GRBV.Subobjective 1.3 Establish the effect of GRBV infection on grape, juice and wine quality.Subobjective 1.4 Assess economic impact of red blotch disease on wine and grape production and nurseries.Objective 2. Identify and develop sustainable strategies to manage GRBV and its vector(s).Subobjective 2.1 Determine presence and biology of potential treehopper vectors in symptomatic vineyards and associated crop and non-crop landscapes.Subobjective 2.2 Improve knowledge of GRBV acquisition and transmission by its vector(s).Subobjective 2.3 Identify sustainable IPM strategies for the management of GRBV vector(s).Subobjective 2.4 Identify effective and economically viable strategies to eliminate GRBV sources (infected vines, vineyards, nurseries and landscape plants).Subobjective 2.5 Evaluate viticultural practices to mitigate the impact of GRBV on infected grapevines in relation to fruit production and quality.Subobjective 2.6 Develop cost-effective GRBV diagnostic tools - a prototype device to detect sub-visible changes in grape leaves at early stages of GRBV infection.Subobjective 2.7 Development of a field level detection method based on isothermal amplification.Objective 3. Implement and evaluate grapevine red blotch disease management programs.Subobjective 3.1 Evaluate grape industry knowledge of red blotch disease and management.Subobjective 3.2 2 Provide stakeholders with results, management guidelines and other outcomes of the Grapevine red blotch disease SCRI project activities.
Project Methods
Methodology, effort and evaluation per (sub)objective:Objective 1:(1.1) Determine GRBV prevalence in at least 5 major CA and OR grape-growing regions or AVAs through surveys and document GRBV spread in states or AVA's; determine genome characteristics of GRBV isolates from these locations.(1.2) Determine GRBV infection status in weeds and perennials proximal to grapevines infected with the virus in CA and OR vineyards in 1.1 by survey. Determine if horizontal spread of GRBV is occurring between grapevines and weeds and perennial hosts.(1.3) Collect samples for transcriptomic and metabolomics analysis and harvest of grapes with resulting wines made. and collect data transcriptomics, metabolomics and sensory analysis.(1.4) Collection of data regarding grape quality, yield and production costs from field trials and data regarding price and price discounts for grapes from GRBV-infected vineyards and analysis of the economic impacts at the vineyard and regional levels.Overall better understanding of GRBD epidemiology will be achieved and the risk of hosts capable of serving as replicative hosts of GRBV in virus management by rogueing will be determined. The impact of GRBV infection on grape, juice and wine composition through multivariate analysis will be determined. Better understanding of the determinants of economic impacts and their relative importance at the vineyard and regional levels will be achieved.Objective 2:(2.1) The seasonal ecology, distribution and biology will be determined of all possible vector insects in relation to virus distribution and spread in key study vineyard. Virus epidemiology will be determined in the vineyard through vector insects occurrence, together with improved virus monitoring and transmission biology experiments.(2.2) Vector transmission studies using either laboratory or field derived infected plants and known (TCAH) or potential vectors. Vectors will be tested for acquisition and plants will be helped for 2 years to develop symptoms. All plants used in inoculations studies will be tested at various times post inoculation, for up to 2 years. Results will be compiled and tests refined for any insects that can transfer the pathogen from infected to clean plant material(2.3) Field studies to determine efficacy of practices such as girdle removal, vineyard floor management, use of antifeedants, and vibration in reducing GRBV spread will be conducted. Experimental practices that reduce GRBV spread by vectors will be integrated with as appropriate in large-scale vineyard evaluations; costs and benefits of practices will be determined(2.4) Collection of data regarding the costs of practices examined in field studies. Analysis of the cost-effectiveness of the experimental practices implemented in the large-scale vineyard evaluations will be conducted.(2.5) Identify vineyards with known history of infection and spread of GRBD to establish viticulture management experiments. Conduct replicated and randomized field experiments to provide sufficient volume for enological analysis, further establish the translocation impediment of phloem transport to mitigate this effect. (2.6, 2.7) Establish the correlation between multispectral features of grape leaves and isothermal amplification data with red blotch diseases. Establish specificity and sensitivity of the multispectral imaging and isothermal amplification approach to detect GRBV.Epidemiology trends from ecology, distribution and biology will inform growers to more effectively mitigate the spread of the virus. Information will be compiled on known and potential vectors in terms of transmission efficiency or the lack thereof. Recommended sustainable IPM strategies for the management of GRBV and its vector(s) will be identified. Better understanding of the determinants of the cost-effectiveness of recommended sustainable IPM strategies and the potential for strategies that can manage GRBV at the regional level to be cost-effective will be achieved. Recommendations of management practices that may be used by grape growers to mitigate the effects of GRBD while providing acceptable berry composition to be used in winemaking will be provided. A portable low-cost device that can be used in a field setting for detection of early stages of GRBV infection will be developed.Objective 3:(3.1) Stakeholder Advisory Panel meets and establishes preferred methods and frequency of updates and communication with Project Directors and investigators; stakeholder surveys developed and implemented; baseline knowledge for GRBD established. Stakeholder Advisory Panel regularly interacts with Red Blotch Project Team and provides recommendations for mid-course corrections; surveys successfully distributed and results compiled, guiding improved stakeholder outreach and extension.(3.2) Holding extension meetings; holding hands-on workshops. Documentation of increased stakeholder knowledge of GRBV and vector identification and management.Stakeholder Advisory Panel and Red Blotch Project Team develop Sustainable IPM strategies and develop needs and plan for future research. Surveys will indicate increased knowledge of GRBV, its vector(s), and management. Sustainable IPM strategies for the management of GRBV and its vector(s) will be made broadly available to stakeholders in CA, OR and across the US by online publications.