A preliminary survey of hazelnut (Corylus avellana L.) viruses in Turkey

Incidence of hazelnut mosaic was tested in hazelnuts from 80 orchards in Bartin, Duzce and Zonguldak provinces, the most widely grown cultivar in the West of Black Sea region. Each of the 80 orchards was sampled in summer 2001, spring 2002 and spring 2003, when a total of 150 samples were collected and tested. 110 of them showed virus symptoms in the leaves including general yellowing, yellow rings and lines, yellow flecking, oak leaf pattern and broad vein banding, while 40 of them were symptomless. Enzyme-linked immunosorbent assays (ELISA) were conducted for Apple mosaic ilarvirus (ApMV) and Prunus necrotic ring spot ilarvirus (PNRSV). Only the samples with symptoms reacted positively to ApMV, while the symptomless samples reacted negatively with both ApMV and PNRSV. Therefore PNRSV was not found in any samples. ApMV, on the other hand, was detected in 50 of the 80 orchards. The incidence of ApMV did not vary significantly among provinces and orchards according to visual observation of the symptoms over a 3-year period. In addition, there was no significant variation in incidence of ApMV among sampling dates within the samples from the three provinces. Some of these samples were mechanically inoculated to a standard series (Chenopodium amaranticolor, C. quinoa and Cucumis sativus) of herbaceous plants. ApMV was also recovered by sap transmission tests. Systemic mottling was observed on C. quinoa and chlorotic local lesions, systemic chlorosis and stunting symptoms were observed on Cucumis sativus.