Timing of collection and preparation of hardwood stem cuttings for propagating hybrid hazelnuts

In previous trials we had found that dormant hybrid hazelnuts crown suckers collected in the fall after leaf drop can be successfully rooted if they are chilled at least until January before being placed in low-cost humidity tents in a greenhouse. The first objective of this experiment was to determine if cuttings could be rooted if started earlier, so as to avoid the heat stress found in the greenhouse in late spring and early summer. The second objective was to see if rooting rates could be improved by collecting non-dormant crown suckers in September and October, before leaf drop. We hypothesized that by collecting stems at a time in the fall when woody plants are translocating resources from leaves to their root systems, we could direct those resources towards growth of adventitious roots. This hypothesis proved to be wrong: stems collected in full leaf died, even with measures to avoid moisture loss from leaves. However, we found that stems collected soon after leaf abscission, in early November, could be rooted if placed in the humidity tents in late November, after only three weeks of artificial chilling at 2 C (36 F). That is much less chilling than we previously thought was needed.