Rotating cross-arm trellis technology for blackberry production

The rotating cross-arm (RCA) technology combines a unique trellis design and cane training protocol. Developed over the last two decades, this technology is beginning to have an impact on the blackberry (Genus Rubus, subgenus Rubus) industry in the United States (US). It has been successfully transferred to growers in more than 21 states in the last two years and contributed to increasing the blackberry acreage by about∼100 ha in the eastern US. Our research and development effort on the RCA technology has shown that 1) winter injury can be reduced by modifying the crop environment and production techniques, 2) white drupe formation can be reduced when fruit is positioned away from direct sunlight, and 3) harvest efficiency is improved when the fruit positioned on one side of the row. Our research has also shown that RCA technology can be used to generate several times more one-node floricane cuttings and long-cane plants than traditional propagation methods. The enclosure technique improved rooting of some cultivars, but there were recalcitrant cultivars like ‘Apache’. Auxin analyses suggested a possible link between IAA concentrations and root induction in floricane cuttings. Consistent production of blackberries was achieved in areas with minimum winter temperatures below −20◦C with the RCA technology. This technology allows the canes to be positioned close to the ground in winter and covered with a floating rowcover. An unexpected result of this winter protection system was some leaves on the floricane remained green throughout the spring and were photosynthetically functional in spring.