Incidence of viruses in two large-scale plantings of blackberry in South Carolina as detected through the use of sentinel plants and RT-PCR.
Some plants in two large-scale blackberry plantings established from virus-indexed planting material displayed symptoms typical of virus infection in the early days of the growing season immediately after planting. Groups of sentinel plants exposed within the plantings for 30-day periods over additional growing seasons, and subsequently screened for the presence of five viruses by reverse transcription PCR, detected Blackberry yellow vein-associated virus (BYVaV), Blackberry virus Y (BVY), Blackberry chlorotic ringspot virus (BCRV), Blackberry virus E (BVE), and Blackberry leaf mottle-associated virus (BLMaV). Because these viruses are thought to be transmitted through the actions of arthropods, and bearing in mind that the plantings had been established with virus-indexed material, it seems that the viruses must be moving into the new crops from adjacent native vegetation and once established moving freely within the crops. BYVaV has been reported from South Carolina previously. A recent publication reports the detection of BLMaV in samples originating from South Carolina and demonstrates transmission of the virus by mites. This is the first report of the detection of BCRV, BVY, and BVE within the state and provides support for the movement of the latter two viruses (BVY and BVE) within established plantings of blackberry as a result of vector activity.