Potato Mop-Top Virus
Potato Mop-Top Virus (PMTV) causes the appearance of unsightly brown markings and rings on affected tubers – known as spraing. This can often lead to failing crops of ware potatoes and seed crops grown for export being rejected.
Common Signs and Symptoms of Potato Mop-Top Virus
The main symptoms of potato mop-top virus in tubers are brown external rings and internal spraing.
Symptoms of PMTV can also be spotted with V shaped markings on the haulms, although these may vary in colour (yellow to green) depending on variety. These symptoms are normally more prevalent during cold springs.
Common Causes and Conditions of Potato Mop-Top Virus
PMTV is transmitted via soil by the powdery scab fungus Spongospora subterranea, and favours cool damp growing areas.
Vulnerable / Immune Varieties
There are no particular potato varieties which have either high resistance or vulnerability to PMTV.
Controlling Potato Mop-Top Virus
Cultural and Methods:
Where possible, eliminate any plants and tubers showing symptoms of PMTV, and avoid infected soils.
Controlling powdery scab will in turn reduce the risk and effects of PMTV in your crops.