Eastern Filbert Blight – A Threat to Hazelnuts

The devastating impact of Eastern Filbert Blight (EFB) has been a significant roadblock to the development of commercial hazelnut orchards outside of Oregon.

EFB is a fungal disease that is native to a wide area in eastern North America. Here it is found naturally associated with its host, our native American hazelnut (C. Americana), on which it causes only limited damage. However, EFB causes severe cankering, branch die-back, and death of susceptible European hazelnuts (C. avellana). The primary limiting factor for growth of commercial European hazelnuts is EFB susceptibility.

Attempts were made in the early 1900s to develop commercial hazelnuts for the eastern United States by hybridizing European and American hazelnuts. But success was limited due to a lack of understanding of EFB and the limited diversity of the genetic resources used in the breeding program.

However, for nearly a century, European hazelnuts thrived in coastal Washington and Oregon, as the climate there was amenable and EFB was naturally absent. Unfortunately, this situation changed dramatically with the discovery of EFB in southwest Washington in the 1960s. EFB is now found throughout the Willamette Valley, where it devastates susceptible orchards and its control adds considerable expense to production costs.

The Hybrid Hazelnut Consortium is researching EFB to better understand the pathosystem. The development of hazelnut cultivars expressing durable resistance is necessary for long-term control of this disease across North America.