Note: Apple mosaic virus (ApMV) and Tulare apple mosaic virus (TApMv) may produce irregular yellow line patterns, whitish vein banding, or irregular yellow flecks in hazelnut leaves. Symptoms might resemble herbicide injury and spread is very slow. Many cultivars show no symptoms. The disease has not been found in commercial orchards in the Pacific Northwest but is common in Europe. Does not seem to affect tree growth or yield. Heat therapy of infected plants for 21 or more days at temperatures alternating every 4 hours between 30°C and 38°C, followed by shoot-tip grafting onto healthy Corylus rootstocks resulted in the elimination of ApMV from infected European hazelnut cultivars. The virus can be spread by propagating from infected trees or through root grafts.
Reference Hadidi, A., Barba, M., Candresse, T., and Jelkmann, W. 2011. Virus and Virus-like Diseases of Pome and Stone Fruits. St. Paul, MN: APS Press.