Multiple Sources of Eastern Filbert Blight Resistance Provide Breeding Utility in New Jersey

The disease eastern filbert blight (EFB), caused by Anisogramma anomala, has prevented commercial hazelnut ( Corylus avellana) production in eastern North America. Recently, several new sources of resistance to EFB have been identified and genetic improvement efforts are underway in multiple regions of the U.S. to develop adapted, disease-resistant cultivars. However, the wide genetic diversity of the pathogen may confound breeding efforts. In this study, we examined six sources of EFB resistance: C. avellana‘Ratoli’ and OSU 495.072, C. americana‘Rush’ and ‘Winkler’, C. heterophylla‘Oygoo’, and the Turkish tree hazel ( C. colurna) hybrid ‘Grand Traverse’. Genotypes representing each resistance source were crossed with susceptible parents resulting in a total of 2,947 seedlings in 46 full-sib progenies. They were field planted at Rutgers University and exposed to the disease over a minimum of six years. Their disease response was evaluated on a scale of 0 to 5 (0 = resistant, 5 = highly susceptible) and segregation patterns were examined. All sources transmitted resistance to their offspring in a dominant manner. Interestingly, segregation patterns compiled by resistance source were relatively similar, with about 50% of the plants showing resistance (rating = 0). The remaining trees in each group were characterized as susceptible, with a majority rated as 4 or 5. These results suggest control by one or a limited number of genes, agree with previous linkage mapping work for several of the sources, and show that resistance has been effective when exposed to multiple isolates of A. anomala. Our results demonstrate transmission of resistance at a high level and suggest that these sources hold considerable promise for breeding plants adapted to New Jersey and other parts of the eastern U.S.