DWARF SOUR CHERRY BREEDING AT THE UNIVERSITY OF SASKATCHEWAN

Sour cherry breeding on the Canadian Prairie began in the 1940s when Dr. Les Kerr began hybridizing Prunus fruticosa x P. cerasusw. In 1966, the University of Saskatchewan initiated sour cherry research with P. fruticosa x P. cerasus seeds from the Siberian Botanical Gardens. After inheriting Dr. Kerr's advanced selections in 1983, controlled crosses were made between hardy selections and sour cherry cultivars from Europe. In recent years, dwarf sour cherries with commercial potential have been selected. Many of the resulting hybrids possess cold hardiness, dwarf stature and good fruit quality. Bred at a zone 2B site, the selections have been tested successfully in Zones 2 and 3. Soluble solids of advanced selections started at 14 to 17 °Brix in late July and increased steadily to 16 to 22 °Brix in late August. Many seedlings have 4.0 g fruits but only two selections average greater than 5.5 g fruits. Height of 7- and 8-year-old seedlings ranged from 1.0 to 3.1 m and averaged 2.4 m. Pull force tests indicated that fruit could be harvested mechanically as early as late July and ease of detachment remained constant to the end of August. Number of suckers ranged from 0 to 24 with an average of 7 per tree. Most fruits in the population are a dark red or black when fully ripe, but a few are bright red. Diseases are extremely rare in all test sites in Saskatchewan. It is not known if this is due to resistance or avoidance. A very early ripening selection, SK Carmine Jewel, was released in 1999. A mid-season selection with large fruit size is planned for release in 2002 or 2003.