Potato Pests and Diseases

Guides to the most common potato pests and diseases from JBA Seed Potatoes.


Slugs are a common problem when growing potatoes but there are a few varieties that are more resistant than others. Slug damage shows up as odd shaped holes on the surface leading into larger holes in the actual tuber itself. Slugs love potatoes that are planted in heavy wet soil.

A late harvest may mean tubers are more at risk from slug attack as slugs are more active around the late autumn period and potatoes are an easy meal for them as they grow near the surface.

Potato Diseases

Black Dot

Common potato disease, normally noticable on tubers but affects the entire plant.

Brown Rot

Serious bacterial potato disease, otherwise referred to as bacterial wilt, which is not established in the UK.

Common Scab

Skin-blemishing potato disease which although has no effect on cooking quality, can greatly affects a crop’s market value.

Dry Rot

Caused by several fungal species in the genus Fusarium, hence the name Fusarium dry rot.


Fungal potato disease caused by Phoma foveata which rots the surface and flesh of tubers during storage.

Late Blight

Common potato disease, caused by Phytophthora infestans, which affects potato and tomato plants with potentially devastating effects, even destroying entire crops in as little as 10 days.

Potato Virus A

Plant pathogenic virus of the family Potyviridae which causes a mild mosaic on potato plants

Potato Viruses S and M

Plant pathogenic viruses, first reported in the Netherlands which appear to be increasing in incidence but fortunately, their symptoms are usually very slight.

Potato Virus X

Plant pathogenic virus of the family Alphaflexiviridae and the order Tymovirales, and is the most common cause of mild mosaic.

Potato Virus Y

Plant pathogenic virus of the family Potyviridae and is among the most important plant viruses that affect commercial potato production.

Leaf Drop Streak

Leaves plants stunted or killed, sometimes causing almost a total loss of yield in plants affected by the disease.

Leaf Roll

Member of the genus Polerovirus and family Luteoviridae which, in affected plants can often cause losses in yields of over 50%

Pink Rot

Sometimes known as ‘Water Rot’ is a potato disease normally associated with high soil moisture at the time when tubers are approaching maturity.

Powdery Scab

Fungal potato disease that affects tubers.  Due to the detrimental effects that powdery scab has on the tubers, it can often lead to the potatoes being rejected.

Silver Scurf

Fungal potato disease which causes blemishes on the tuber’s surface.

Skin Spot

Fungal pathogen of potatoes which is normally invisible until after around two months of storage, when areas of infected tissue begins to show spots.

Spraing – Potato Mop-Top Virus

Causes the appearance of unsightly brown markings and rings on affected tubers – known as spraing

Spraing – Tobacco Rattle Virus

One of the causes of the appearance of unsightly brown markings and rings on affected tubers – known as spraing, which can often lead to ware crops becoming unsellable.

Stem Canker and Black Scurf

Potato disease which causes the appearance of black patches on the surface of tubers.

Target Spot – Early Blight

Potato disease which attacks older leaves as the plant ages or when the plant is under stress.

Violet Root Rot

Caused by a soil borne fungus which develops in the field during growing seasons.  It’s often found in carrots and parsnips, but can also affect potato crops.

Wart Disease

Aka potato canker, caused by a soil borne fungus and was once a very serious problem for potato crops but better controlled in recent times.

Watery Wound Rot

Infection which starts on the surface of the tuber and heavily affects the interior, rotting away the tuber’s flesh.