2018 ASHS Annual Conference

The OSU breeding program routinely uses tie-off layerage (stooling with shoot girdling) to clonally propagate hazelnut trees for yield trials and field exposure to eastern filbert blight (EFB) for disease susceptibility screening. For greenhouse EFB inoculations, trees are grafted in a heated greenhouse to promote callusing at the graft union. A hot-callusing pipe can be used for bench grafting in lieu of a greenhouse, and is suitable for many other species where dormant season open-field grafting is unsuccessful. Grafting also allows establishment of new orchards on clonal rootstocks that produce few suckers. Field grafting with a high success rate is possible if it is delayed until late spring, using scions collected in mid-winter and stored at -1 °C. Micropropagation is now used for rapid increase of new cultivars from the breeding program for commercial orchard planting and establishment of layering beds. Propagation by softwood cuttings from suckers and side branches on container-grown micropropagated trees is also successful in mid- to late- spring.