Phenotypic Diversity of Wild Black Raspberry Germplasm

Since the 1950s, a lack of genetic diversity in elite black raspberry (Rubus occidentalis L.) germplasm has been recognized as a major factor limiting breeding progress.  Attempts to incorporate desirable traits from other Rubus species have been met with limited success.  In 2006, we began an extensive collection and evaluation of wild black raspberry germplasm from across the species’ native range.  To date, more than 130 wild populations have been sampled from 27 states and two Canadian provinces.  These populations show significant variation in a wide range of traits including vigor, plant architecture, thorniness, flowering and ripening dates, and sensitivity to Verticillium wilt.  Some of these traits show regional trends, and will direct where future germplasm collection efforts should focus.  Variation in these wild black raspberry populations will be useful for breeding disease resistant cultivars that give growers more options and better meet the needs of the industry.