|Authors: ||T.J. Molnar, J.M. Capik, J.C. Goffreda|
|Keywords: ||Corylus avellana, Corylus Americana, genetic improvement, disease resistance|
Great progress is being made at Oregon State University (OSU) to identify and characterize hazelnut (Corylus spp.) genotypes resistant to the disease Eastern Filbert Blight (EFB), caused by Anisogramma anomala (Peck) E. Müller.
However, little is known about how these sources of resistance will respond to EFB in regions outside of the Pacific Northwest, especially when incorporated into advanced generation progeny.
To examine this question, controlled hybridizations were made in 2000 at OSU between genotypes identified as highly resistant to EFB and genotypes susceptible to the disease.
Sources of resistance evaluated were derived from ‘Zimmerman’, ‘Ratoli’, ‘Grand Traverse’, and ‘Yoder #5’. Progeny of three additional crosses, designed to yield offspring expressing moderate to moderately-high levels of quantitative resistance, were also examined.
Resulting seedlings were exposed to EFB in 2003-2007 and were evaluated for their response in 2008. Plants were rated on a scale of 0 to 5, in which 0 represents no sign of EFB and 5 represents all branches exhibiting cankers.
Progeny derived from ‘Zimmerman’ and ‘Ratoli’ segregated according to previous reports (3 resistant : 1 susceptible and 1 resistant : 1 susceptible, respectively). Interestingly, progeny of ‘Yoder #5’, a cultivar believed to have obtained its resistance from Corylus americana Marsh., segregated in a pattern that fit a ratio of 1 resistant : 1 susceptible. ‘Grand Traverse’ transmitted a high level of resistance to 25% of its progeny.
Most seedlings of the progenies designed to express quantitative resistance were highly susceptible to EFB. This study suggests ‘Zimmerman’, ‘Ratoli’, ‘Grand Traverse’, and ‘Yoder #5’ may be directly useful in breeding resistant plants for the eastern USA, but high levels of quantitative resistance may be more difficult to obtain without recurrent selection of each generation under the severe disease pressure found in this region.
Download Adobe Acrobat Reader (free software to read PDF files)