NGWI-Supported Trunk Diseases Project Concludes
With no cure for trunk diseases, prevention is essential. Gaps in our ability to detect the pathogens in the nursery and the field, insufficient knowledge of disease-resistant cultivars, and limited grower adoption of preventive practices contributed to a high disease incidence. Accordingly, the team proposed three objectives, outlined below with highlights of their results as they relate to grape.
Goal 1: Develop new detection tools for diagnosticians, growers and nurseries
- Developed an assay to detect infection of woody tissues as an expression of grape genes and pathogen genes, which can be used in nurseries to screen mother plants and other propagation materials. See www.TrunkDiseaseID.org for the team’s DNA-sequence database on which the assay is based.
- Justified to grape growers the need for prevention of trunk diseases in young vineyards, using spore traps for detection of trunk pathogens.
Goal 2: Identify disease-resistant cultivars and germplasm accessions
- Collaborated with VitisGen (also an NGWI-supported SCRI project) to identify molecular markers of grape resistance to Phomopsis dieback, thereby establishing a basis for future crosses that are trunk-disease resistant. The team notes that, as acceptance of new cultivars in the table-grape industry is high, this work accelerates the possibility of resistant plant material as a long-term approach for trunk-disease management for this sector.
- Identified table grapes with resistance to Esca, a common trunk disease in California’s table-grape regions. The team found that the wood anatomy–particularly the size of the xylem vessels–seems to render plants more susceptible and may be a phenotype to screen for in breeding Esca-resistant table grapes. With its large xylem vessels, Thompson Seedless is more vulnerable than Flame Seedless and Scarlet Royal, which have smaller vessels.
Goal 3: Develop and deploy extension tools that increase adoption of preventative practices in young vineyards
- Used impactful economic (vs. scientific) data to demonstrate the long-term benefits of prevention. The team also created excellent management plans and an economic decision tool, available online.