Emerging and Reemerging Virus Diseases of Blueberry and Cranberry

It should be expected that as blueberry cultivation continues to expand into new areas, the plants will become exposed to viruses that have not previously been observed in blueberry. Since the last symposium in 2004, Blueberry scorch virus continues to be a major concern in the USA Pacific Northwest and it has also been detected in New England as well as the Netherlands and Italy in Europe. In the past, blueberry mosaic symptoms appeared to spread very slowly or not at all, while in recent years, the disease has been spreading within fields and appearing in new fields. Blueberry mosaic symptoms have been observed in many production areas. A high molecular weight double-stranded RNA (dsRNA) has been detected in plants with mosaic symptoms indicating the presence of a virus, but the virus has yet to be characterized. Blueberry red ringspot virus has been detected in the southeastern USA. A virus has been detected in plants exhibiting Blueberry fruit drop symptoms in the Pacific Northwest. In cranberry, funky flower symptoms have been observed in the northeastern USA for the past 10 years. Recently, Cucumber mosaic virus has been detected in plants exhibiting funky flower symptoms. Efforts to demonstrate a causal relationship between Cucumber mosaic virus and disease symptoms are underway. Tobacco streak virus was first reported from cranberry plants imported into Scotland and has since been detected in New Jersey. A breakthrough in detection of viruses in Vaccinium species has come from the development of a dsRNA extraction method that works reliably with blueberry and cranberry. Cloning and sequencing of purified dsRNA has been the most successful means for the characterization of viruses of woody plants that can not be transmitted to herbaceous hosts.