Horizontal Cane Orientation and Rowcover Application Improve Winter Survival and Yield of Trailing ‘Siskiyou’ Blackberry

Using the rotating cross-arm (RCA) trellis and cane training system, lateral canes of trailing ‘Siskiyou’ blackberry (genus Rubus subgenus Rubus) were kept vertically or rotated down to horizontal so that plant canopy was close to the ground. In winter, the plots were either covered with a non-woven rowcover (RC) or left uncovered. Cane injury was least in plants with lateral canes oriented horizontally and covered. Cane injury was high in plants with lateral canes oriented vertically in winter, whether covered or not, and among plants with lateral canes laid close to the ground but not covered. Among ‘Siskiyou’ plants that had lateral canes oriented horizontally, 280 flower clusters and 6.0 kg fruit/plant were produced on plants that had a RC in the winter compared with only 72 flower clusters and 1.7 kg fruit/plant for plants that were not covered in winter, in 2009. Fewer flower clusters developed and the yield was ≤2 kg/plant on plants with lateral canes oriented vertically. Yield differences between the most and least productive treatments were low in 2010 because of milder winter conditions and snowfall during the coldest periods that fully or partially covered the lateral canes oriented horizontally and close to the ground. The RC treatment had no effect on cane injury or yield when lateral canes were oriented vertically. The findings suggested that ‘Siskiyou’ blackberry can be grown in the eastern United States, where winter injury has frequently caused a crop failure, by positioning the lateral canes close to the ground and covering plants with a RC.