Potato Virus X
Potato Virus X (PVX) is a plant pathogenic virus of the family Alphaflexiviridae and the order Tymovirales, and is the most common cause of mild mosaic.
Symptoms of Virus X
Potato virus X is very difficult to spot as there are very few symptoms however one clue to look out for is a reduction in yields (typically around 15%).
A mosaic pattern of light and dark green on leaflets can exist between veins and normally there is no leaf distortion, however some strains do arise which cause a severe mosaic.
Common Causes and Conditions of Potato Virus X
PVX is spread by either direct contact (between plants) or indirect contact (by man or machinery) when passing through the crop. It can remain infective on clothing and machinery for several weeks if kept damp. Not transmitted by aphids.
Vulnerable / Immune Varieties
There are no particular potato varieties particularly at risk of PVX, however a few are immune, including: Cara, King Edward, Maris Piper, Pentland Dell, Pentland Javelin, Pentland Squire and Sante.
Controlling Potato Virus X
PVX can be controlled by disinfecting all clothes and machinery before entering tested and unaffected tuber stocks, and multiplication of seed stocks from virus-tested plants by specialist seed potato growers from good seed growing areas.
There are currently no chemical solutions available in the UK to prevent or control PVX.