"‘Jefferson’ is a new hazelnut (Corylus avellana L.) cultivar for the in-shell market. It was released by the Oregon Agricultural Experiment Station in Jan. 2009 as a replacement for ‘Barcelona’. It combines complete resistance to (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller with high nut yield, large nut size, and good kernel quality. Compared with ‘Barcelona’, Oregon's leading cultivar, ‘Jefferson’ has smaller trees, higher nut yield, and much higher nut yield efficiency. Pellicle removal ratings are better than ‘Barcelona’, and kernel quality is suitable for use in chocolate products and baked goods, although kernel size is larger than ideal for the kernel market. ‘Jefferson’ is recommended for Oregon's Willamette Valley and other areas with a similar climate."