The Impact of Severity and Time of Tipping and Hedging on Performance of Primocane-fruiting Blackberry in a Tunnel

Abstract

Summer pruning systems were compared for ‘Prime-Jan’® primocane-fruiting blackberry (Rubus subgenus Rubus) grown in a fully closed, plastic covered tunnel in Aurora, OR. Individual canes were soft-tipped (by removing 0.10 m) or hard-tipped (removing 0.45 m) to a 1-m height on each of four dates in 2008 and 2009. On average, canes that were hard-tipped produced more branches and had more fruit/cane than soft-tipped canes. Canes that were tipped early (22–27 June) produced more fruit/cane than those tipped later (7–24 July). When canes were hard-tipped early in the season, the number of fruit/cane was increased threefold compared with soft-tipping canes early. In contrast, when plots were hedged to 1-m tall lightly (“soft” hedge removing 0.10 m) on 22–27 June or more severely (“hard” hedge, removing 0.45 m) on 29 June–2 July, using shears, there was no significant effect on yield/plot. The hard-hedge treatments may have performed better if they had been done earlier or at the same time as the soft-hedge treatments; this would only have been possible if canes had been cut back (hedged) to a shorter height than 1 m. Hard hedging, done ≈1 week later than soft hedging, delayed the fruiting season by 10–14 days. Fruit harvest continued until early to mid-November. Daily average air temperature in the closed tunnel was 2–7 °F warmer than the outside and fruit were protected from autumn rainfall. Hard-tipping individual canes, by hand, or hedging primocanes mechanically early in the season shows promise in this crop for maximizing economic returns.