The invention provides methods and kits for detecting potato viruses in a potato plant.In particular, the invention provides for reverse-transcriptase polymerase chain reaction (RT- PCR)-based methods for simultaneously detecting one or more potato virus, preferably selected from Potato leafroll virus (PLRV), Potato virus X (PVX), Potato virus Y (PVY), Potato virus A (PVA), Potato virus M (PVM), and Potato virus S (PVS), and potato actin mRNA as internal control for the RT-PCR. The invention further provides for kits of parts useful in these methods and comprising one or more primer pairs for amplifying viral RNA of one or more potato virus and a primer pair for amplifying potato actin mRNA by RT- PCR, and optionally comprising probes for detecting the amplicons.