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Evaluating sources of hazelnut resistance to eastern filbert blight in New Jersey, USA

Molnar, T. J., Morey, K., Capik, J. M.
Acta horticulturae 2014 no.1052 pp. 45-59
Corylus avellana, biological resistance, blight, branches, breeding, dieback, field experimentation, fungi, hazelnuts, planting, progeny, seedlings, stem cankers, tree mortality, New Jersey, Oregon
Eastern filbert blight (EFB), caused by the fungus Anisogramma anomala, is the major limiting factor of hazelnut (Corylus avellana) production in North America. Most plants of C. avellana are highly susceptible to EFB, a disease which causes stem cankers, branch die-back, and eventual tree death. The disease is now found throughout the Willamette Valley of Oregon, the location of commercial hazelnut production in the United States, since being inadvertently introduced to the region in the late 1960s. Fortunately, significant progress has been made at Oregon State University (OSU), Corvallis, OR, to identify and characterize new hazelnut accessions resistant to EFB, including their use in breeding. However, these sources of resistance should also be tested in the eastern United States to evaluate their usefulness for this region, where the causal fungus is endemic and likely more diverse. For this study, controlled hybridizations were made in 2004 through 2007 at OSU and Rutgers University, New Brunswick, NJ, between accessions identified as resistant to EFB and those susceptible to the disease. Sources of resistance evaluated were derived from ‘Gasaway’, OSU 408.040, ‘Ratoli’, ‘Crevenje’, ‘Culpla’ and ‘Uebov’. The resulting seedlings were planted in field trials in New Jersey and exposed to EFB annually. Plants were evaluated in January 2012 for response to the disease based on a scale of 0 to 5, in which 0 represents no sign of EFB and 5 represents all branches exhibiting cankers. Results showed progeny derived from ‘Gasaway’ and OSU 408.040 developed EFB cankers on more plants than were expected, based on previous studies in Oregon. However, a high level of tolerance was still observed. The single progeny of ‘Ratoli’ confirmed previous findings of segregation for resistance in a ratio of one resistant to one susceptible seedling. Interestingly, the progenies of ‘Culpla’, whose inheritance of resistance was not yet reported, showed unclear results; one progeny produced a significant proportion of resistant or tolerant seedlings, with the other progeny producing very few. Roughly one-quarter of the ‘Crevenje’ seedlings exhibited resistance. ‘Uebov’ transmitted almost no resistance to its offspring.