Title: Primocane-fruiting Blackberries: The Effect of Summer-Pruning, Tipping, and Chilling on Primocane Morphology, Fruiting Season, and Yield.

The effect of primocane management on flowering and fruiting patterns was studied in primocane-fruiting blackberry (Rubus subgenus Rubus, Watson) cultivars ‘Prime-Jan’ ® and ‘Prime-Jim’ ® over two years. Primocanes that were “soft-tipped” (upper 2-5 cm removed) at 1.0 m were compared to un-tipped canes. In both years, soft-tipped primocanes developed 2-3 fold more branches and almost twice the number of flowers as un-tipped canes. ‘Prime-Jan ’ and ‘Prime-Jim ’ began blooming on the apices of branches of soft-tipped canes in mid-July, while un-tipped primocanes began to bloom on the apex in late July in 2005 and 2006. Within an 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. The blooming pattern within an inflorescence was similar for soft-tipped and un-tipped primocanes. Primocane management treatments studied in the field were: 1) primocanes soft-tipped at 0.5 m, 2) primocanes soft-tipped once reaching 1.5 m, 3) primocanes re-cut (to crown) once reaching 0.5 m and subsequent primocanes left un-tipped, 4) inflorescence removed after first open bloom, and 5) primocanes soft-tipped at 1.0 m [control]. Primocane growth, flowering and yield were affected by treatment, but not cultivar. Cultivars responded similarly to management treatments. Primocanes tha