Investigating the viral causes of internal necrosis in carrot

Internal necrosis has been observed in UK carrots for at least 10 years and has been linked anecdotally to virus infection. In the 2009 growing season some growers had up to 10% loss of yield with these symptoms. By using a metagenomic approach with high throughput sequencing technology and a statistical analysis Carrot yellow leaf virus (CYLV) has been putatively linked to internal necrosis. Additionally a torrado virus has been identified and putatively named 'Carrot torrado virus' (CTV). Preliminary investigations into the prevalence of CYLV and CTV in UK carrot crops have found virus infection levels of up to 46% virus and incidence of CYLV of up to 35%; and CTV of up to 25% plants affected. These data suggest that CTV may have a similar epidemiology to CYLV, implicating an aphid vector for transmission.