Eastern Filbert blight caused by Anisogramma anomala on European hazelnuts
Eastern Filbert blight is caused by the ascomycete Anisogramma anomala, an indigenous pathogen of Corylus americana in eastern North America. The disease was not reported west of the Rocky Mountains until 1973, when it was found in an orchard of European hazelnut (C. avellana) in Washington State (US). By 1979, the disease had spread through the hazelnut-growing areas of Washington and in 1986 it was found in the Willamette Valley in Oregon where 98% of the US hazelnut production is located. Further surveys showed that the disease is now established in this valley.
The disease cycle of this disease is initiated in the spring when ascospores of A. anomala infect breaking vegetative buds and young vegetative shoots. The fungus systematically colonizes the cambial tissue of branches, usually producing a canker 13-15 months after the infection. Canker expansion eventually girdles branches and limbs, resulting in canopy dieback and death of trees in 4-10 years.
Experiments were carried out in Oregon to test the susceptibility of European hazelnut clones to eastern filbert blight. Several cultivars obtained from Europe were tested as well as cultivars of European hazelnut from the USA. It was found that several cultivars from Europe showed a very high susceptibility to this disease.
Pinkerton, J.N.; Johnson, K.B.; Mehlenbacher, S.A.; Pscheidt, J.W. (1993) Susceptibility of European hazelnut clones to eastern Filbert blight.
Plant Disease 77, 261-266.