Flowering and fruiting patterns of primocane-fruiting blackberries

The flowering morphology of the erect, thorny, primocane-fruiting blackberry (Rubus L. subgenus Rubus, Watson) cultivars 'Prime-Jan' and 'Prime-Jim' were studied in 2005 and 2006 in Aurora, OR. Primocanes that were "soft-tipped" in early summer to 1 rn were compared with untipped primocanes. In both years, soft-tipped primocanes developed two- to threefold more branches and almost twice the number of flowers as untipped canes. 'Prime-Jan' and 'Prime-Jim' began blooming on the branches of soft-tipped canes in mid-July, whereas untipped primocanes began to bloom in late July in 2005 and 2006. Within a primocane inflorescence, the terminal or distal flower was always the first to open followed by terminal flowers from axes located on the basal portion of the inflorescence. Flowers then opened acropetally within the inflorescence, with the exception of the most basal flower, which was typically the last to open. The blooming pattern within an inflorescence was similar for soft-tipped and untipped primocanes. Days from anthesis to black fruit for soft-tipped and untipped primocanes averaged 45 to 51 d in both years, depending on cultivar.