Productivity of Pruned and Unpruned ‘Triple Crown' Blackberry Plants on the Rotating Cross-arm Trellis System

In 2012 and 2013, mature ‘Triple Crown’ blackberry plants were trained on the rotating cross-arm trellis (RCA) trellis.  By the end of the summer, as many as 30 lateral canes with lengths >3.5 m had developed on three primocanes that had been bent at a 0.50-m height.  In winter, the lateral canes were pruned back to 1.5 m lengths or left un-pruned to determine the effect of lateral cane length on budbreak, fruit cluster number, fruit number per cluster, fruit weight, and yield.   On a plant basis, pruned and unpruned plants possessed 36 and 54 m of cane length and 706 and 932 nodes, respectively. Pruned lateral canes had node numbers that were only 60% of unpruned lateral canes, but 68% of buds developed a flowering shoot compared to only 32% of nodes on unpruned laterals.  Shortening the lateral canes to 1.5 m did not result in reduction of plant yield, fruit number, or fruit weight.  The results indicated that pruning lateral canes to 1.5 m length was advantageous for blackberries trained on the RCA trellis.