Sweet cherry breeding at Washington State University

Sweet cherry breeding at IAREC began in 1949 under USDA breeder Harold Fogle, whose most important new cherry cultivars were 'Rainier' and 'Chinook'. 'Rainier' has become the highest value cherry produced in the Pacific Northwest, due to its acceptance as the premier cherry for Asian export markets and major U.S. cities. The breeding program was transferred to Washington State University breeder Tom Toyama in the early 1960s; at that time, the primary objectives were to 1) expand ripening times, especially for early season harvest (before 'Bing'); 2) develop large, very firm, mahogany red cherries with good sweet/tart flavor; and 3) develop self-fertile varieties. Since Dr. Toyama's retirement in the 1980s, selection evaluations continued under WSU physiologist Ed Proebsting, resulting in the recent naming and release of 'Chelan', 'Index', 'Cashmere', 'Glacier','Simcoe', and 'Olympus' sweet cherries. 'Chelan' has received the greatest interest to date, due to its early ripening period (10-12 days earlier of 'Bing') and low incidence of raincracking. Following Dr. Proebsting's retirement in 1993, the WSU sweet cherry physiology and germplasm research programs were combined under his successor, Dr. Gregory Lang. Our subsequent efforts have concentrated on continuing the identification and evaluation of new "elite" selections from Dr. Toyama's crosses, as well as renewing hybridizations for future variety development. Among the interesting new elite selections are some with very large fruit size (13-14 g, 29-32 mm), high sugar contents (18-22 degrees Brix), and ripening times from similar to 10 days before 'Bing' to similar to 10 days after 'Bing'. In addition to the breeding objectives above, additional priorities include 4) characterizing genetic resistance to powdery mildew and 5) developing late blooming cultivars to reduce the potential for spring frost damage. Key characteristics of the most recent WSU sweet cherry cultivar releases and new "elite" selections are described and discussed.