Blight Browning and death of foliage and rotting tubers. Unlikely to affect earlies, but a problem from July onwards in wet, humid summers.
Solution Cut off affected foliage and harvest tubers as soon as possible, cutting out all black areas. Do not compost infected foliage or tubers, and do not grow potatoes on previously infected ground.
Eelworm Poor growth, yellowing and wilting caused by these underground pests.
Solution Practice crop rotation and avoid growing plants on land previously occupied by potatoes. Plant eelworm-resistant varieties.
Slugs Keeled slugs tunnel into tubers and can make serious inroads into crops of maincrop tubers.
Solution Harvest as soon as the crop is ready. Avoid freshly manured ground, which will be more attractive to the molluscs. Organic controls such as Nemaslug can be watered on when the soil is at a sufficiently high temperature. Plant slug-resistant varieties.
Woodlice Generally attack after slugs have made inroads.
Solution Harvest early to avoid them.
Scab Prevalent on light, dry soils and those containing chalk. Solution Choose scab-resistant varieties. All traces of scab can be removed by peeling the spuds and no significant harm is done.
Small potatoes Generally caused by lack of moisture and nutrients.
Solution Add fertiliser at planting and water thoroughly during dry spells. Manure an area ready for growing a hungry vegetable this year, and then use the same place for your potatoes the following year.
Viral diseases Distorted and yellowing foliage, and reduced yield.
Solution Buy and plant only ‘certified’ seed potatoes, which should be virus-free.
Blight causes the leaves to shrivel and turn brown before spreading to the tubers, which rot
Small, perfectly formed holes signify slug attack, while scabs show that the crop is infected by bacteria