Barley Barley Crop Icon Brassicas Brassicas Crop Icon Sugar Beet Sugar Beet Carrots Carrots Icon Leeks Leek Icon Maize Maize Icon Oilseed Oilseed Icon Onions Onions Icon Other Cereals Other Cereals Icon O R T Peas And Beans Peas and beans Icon Potatoes Potatoes Icon Salad Crops Salad Crops Icon Soft Fruits Crops Soft Fruits Icon Top Fruits Crops Top Fruits Icon Wheat Crops Wheat Icon Calendar Calendar icon Arrow Next Arrow Previous Close Checkmark

Spraing - Mop Top

Potato Mop Top Virus (PMTV)

Pathogen

Virus

Hosts

Potatoes and certain weed species such as black nightshade

Symptoms

Brown arcs in the tuber flesh and raised rings on the tuber surface, but no foliage symptoms in the year of infection. Plants grown from infected seed have stunted stems (mop top), plus yellow spots and 'V' shaped markings on the leaves.

Development

The virus is carried by spores of the powdery scab fungus (Spongospora subterranea) which may be introduced with the seed tuber or survive in the soil from previous crops. In the soil it can survive inside the fungal spore for over 15 years.

Favourable Factors

Cool, damp soils in June/July. Foliage symptoms are particularly apparent in cold springs.

Importance

30-50% of plants from infected tubers exhibit foliage symptoms, but the disease is generally of little economic importance in the UK.

Control

Identification and Management of potato diseases

Find out more information on the key disease threats to your potato crop. For each disease you will find out the importance of the disease in terms of potential yield penalty, how to identify the disease in its early stages and our advice on the best control strategies.

View now