Progress breeding for resistance to eastern filbert blight in the eastern United States

Abstract

Eastern filbert blight (EFB) is a hazelnut disease caused by Anisogramma anomala, a fungus endemic to North America where it can be found associated with the wild hazelnut Corylus americana. While C. americana is resistant to EFB, the commercial hazelnut C. avellana is highly susceptible and typically dies within 5 years from exposure. A hazelnut breeding program was initiated in 1996 at Rutgers University in New Brunswick, New Jersey. The early objective was to identify sources of resistance to EFB for use in breeding regionally adapted, EFB-resistant plants to support the establishment of a hazelnut industry in eastern USA. By working with Oregon State University (OSU) and international colleagues, germplasm collections were made in Russia, Ukraine, Poland, Georgia, Latvia, Lithuania, Estonia, Italy, and Turkey. Over 5,000 seedlings were grown and evaluated for response to EFB. While most plants succumbed to EFB, about three percent were found to be resistant. Interestingly, the resistant plants spanned nearly all collection locations and molecular markers have shown them to be highly diverse. Today, we have access to over 100 EFB-resistant accessions selected from more than 60 locations, which represents a significant pool of germplasm to support breeding. Recent studies have shown that most resistance seems to be controlled by only one or a few major genes; R-gene mapping projects are underway at Rutgers as well as Oregon State University. We continue to study new sources of resistance for use in a focused cultivar improvement program.