First report of Blueberry red ringspot virus in highbush blueberry in the Czech Republic.
A collection of highbush blueberry (Vaccinium corymbosum) cultivars planted in the field for propagation in South Bohemia was surveyed in May and July of 2009 for the occurrence of detrimental viruses. A total of 67 plants of 10 cultivars (Berkeley, Burlington, Blue Crop, Bluetta, Darrow, Duke, Gila, Jersey, Late Blue, and Northland), were observed for typical Blueberry red ringspot virus (BRRV) symptoms that appear as reddish ring spots and blotches on stems and fruits, exclusively on the upper surface of the older leaves but not the underside. Samples of leaves were collected and maintained at -20°C until used for DNA extraction, then assayed for BRRV infection using PCR. Controls originated from the same blueberry cultivars in vitro. No BRRV symptoms were observed on the plants in early spring, yet BRRV was detected in one symptom-free bush of Darrow by PCR. In July, typical symptoms developed on that and another Darrow bush that was also positive by PCR. The disease was likely introduced in infected planting material, since no highbush blueberry plantations exist in the vicinity and V. corymbosum is not native to the Czech Republic. This is thought to be the first report of BRRV in V. corymbosum in the Czech Republic. Symptom observation and PCR testing for BRRV should, therefore, be incorporated into the certification scheme for highbush blueberry in the Czech Republic.