Adoption of Best Management Practices for Grapevine Leafroll and Red Blotch Diseases: A Survey of West Coast Growers

Grapevine leafroll (GLD) and red blotch (RBD) diseases threaten the sustainability of the USA wine grape industry. To understand factors influencing the adoption of disease management practices, we surveyed wine grape industry professionals in California, Oregon, and Washington (n=154). Economic factors were the fundamental cost of implementing management practices and the ability to sell product from diseased vines (salability). Respondents with reduced salability were more likely to adopt virus testing, replace infected vines, and view these practices as economically favorable. Salability was a strong driver for adoption among Californian respondents, but lesser so in Washington where wineries appeared more willing to accept infected product. Respondents who had acquired technical knowledge of disease ecology were more likely to adopt management practices and to perceive them as economical. Conversely, when there was a lack of knowledge of GLD ecology, notably that mealybugs transmit the pathogen, , adoption was reduced and practices were considered less economical,. Factors affecting adoption were broadly generalizable across diseases. However, knowledge of GLD ecology was more strongly associated with adoption, likely reflecting the remaining knowledge gaps in RBD related to vector ecology and field spread. An emphasis on grower knowledge acquisition and the development of economical disease management practices can improve adoption of best management practices for viral diseases of grapevine.