Location: Crops Pathology and Genetics Research
Project Number: 2032-21220-008-11-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jul 1, 2018
End Date: May 31, 2021
Objectives are: 1) Determine the identity and distribution of Esca pathogens in new grape-production systems and regions: California table and raisin grapes, and Washington wine and juice grapes, 2) Confirm the pathogenicity of wood-rotting fungi associated with Esca, with new fungal isolates identified from California and Washington, and 3) Identify effective practices to prevent infections of pruning wounds.
Symptomatic vineyards have been identified by cooperative extension farm advisors, pest-control advisers, and regional grower groups, to examine in year 1. Fungi isolated from wood samples will be identified to the species level, and new species not previously associated with Esca will be evaluated in pathogenicity tests. In year 2, co-inoculations will be done in the greenhouse, to test whether the wood-rotting Basidiomycete fungi (previously assumed to be secondary invaders) are pathogenic alone or in mixed infection with the Ascomycete fungi that are know to be causal pathogens of Esca. With a clear understanding of which fungi cause Esca in each production system, starting in year 2 and continuing through year 3, we will field evaluate the efficacy of pruning-wound protectants, using controlled inoculations with local fungal isolates. Materials will include those registered in California for table and raisin grapes (fungicides Topsin, Rally, Luna Experience, and Pristine). No materials are registered in Washington state, and so this field study will gather the necessary data to obtain a Special Local Needs permit.