| Eastern filbert blight (EFB), caused by the fungus Anisogramma anomala (Peck) E. Muller, is a destructive disease of European hazelnut (Corylus avellana). While the wild North American hazelnut, C. americana, only experiences minor symptoms, commercially grown C. avellana is extremely susceptible. Anisogramma anomala, whose range includes much of the U.S. east of the Rocky Mountains, is considered to be the main impediment to commercial hazelnut production in the East. As such, identifying and developing resistant C. avellana germplasm is critical to establishing an industry in this region. To support this goal, several research projects were undertaken. In the first study, 193 clonal hazelnut accessions spanning multiple Corylus species and inter-specific hybrids were examined for their disease response to EFB in New Jersey. In summary, despite the fact that many of the plants were shown to be resistant in Oregon, some accessions developed EFB in New Jersey. These results support previous work that suggests different isolates of the pathogen are present in the eastern U.S., and resistance may not hold up unilaterally. A second study included searching for new sources of resistance to EFB. New hazelnut germplasm was collected from Russia, Poland, and Ukraine and exposed to EFB. After at least five years of exposure, plants were rated for iii the presence of EFB. At completion, 76 trees from 24 seed lots were found to be free of EFB with several trees that also produced excellent quality kernels. The final study was predicated on evaluating known resistant plants for their flowering phenology in New Jersey. Phenological timing of flowering in hazelnuts is critical to ensure complete pollination and high crop yields. Nineteen hazelnut accessions were evaluated compared to daily temperatures over 4 years. Results showed that the accessions followed a similar progression of bloom each year (both staminate and pistillate flowers), which allowed their placement into Early, Mid-, and Late flowering groups. These findings represent the first efforts to report on flowering and bud break phenology in New Jersey, where the winter climate is colder and more variable than that of Oregon and other commercial hazelnut growing regions. |
