Location: Forage Seed and Cereal Research Unit
Project Number: 2072-21000-051-004-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Oct 1, 2017
End Date: Sep 30, 2022
Objective:
The objective of this breeding project is to develop disease resistant hop cultivars in a program centered in Washington State and release them publicly. It is crucial to the funding organization that the developed germplasm be released into the public domain, and there is currently no public sector breeding in Washington State. The research will prioritize breeding new hop cultivars for improved or novel: 1) sensory and aroma requirements, as determined by stakeholders, and 2) improved disease resistance.
Approach:
A traditional breeding approach will be employed that results in released cultivars in approximately 12 years. The timing of trait selection for this project will largely conform to what has traditionally been done in the USDA hop breeding program. Greenhouse grown plants will be evaluated for disease resistance, vigor, and plant growth characteristics; female plants will be selected while growing in a short-trellis system (both year 2). Single-hill plants (years 3, 4 and 5) will be evaluated for yield, vigor, plant structure, and disease resistance. Chemistry may be evaluated in year 5 if population sizes are small enough for assays that are feasible and economical. Advanced line trials (years 6, 7, and 8) and large-scale grower trials (years 9, 10 and 11) will be evaluated for yield, vigor, plant structure, and in test brews. Promising selections will be inserted in the clean plant network and released in year 12. Advanced trials and large-scale grower trials are expected to be in grower fields that are protected by a minimal fungicide program, and therefore will not be evaluated vigorously for disease resistance.
Genotypes selected for downy mildew and powdery mildew resistance in greenhouse tests will likely contain numerous individuals that escaped infection. To identify and eliminate disease escapes, genotypes advanced out of greenhouse experiments will be retested in field experiments. Powdery mildew field testing will occur as single hills grown in Prosser, Washington. Assessments of aroma and agronomic characteristics will occur concurrently in these experiments. Downy mildew field testing will occur in a short trellis system in Corvallis, Oregon and only downy mildew resistance will be assessed in these experiments. The selection of this site is solely based on the need to get reliable disease epidemics for accurate assessment of resistance. Data from both disease nurseries will be used to select plants for promotion to advanced testing.
Selection techniques will be implemented to identify genotypes that express at least partial resistance against multiple diseases and pathogen strains. To achieve this, parents will be selected that have diverse and complementary resistances and disease screenings will use inoculum in greenhouse experiments that are a mixture of strains or successive inoculations with different strains. The specific method and strains used will depend on the genetic background of the germplasm. We may also employ single-hill field plot designs that incorporate a mixture of hop cultivars likely to promote and spread different but naturally occurring disease strains.
