Seed potatoes and their most common pests

IMG_2998The versatile potato remains the most popular vegetables to grow for Irish gardener. However growing your own spuds is not without its drawbacks and challenges as they are susceptible to both disease and pest attacks in many forms. Everyone is aware of the harm that seed potatoes blight can cause but in this article we hope to outline the range of other pests and diseases surrounding potatoes and aim to solve them for you

Slugs: Soil borne slugs are a common pest of potatoes and are known to burrow their way into the tubers leaving large hollows which lead to rotting. Slugs are most common in heavy clay soils and their numbers greatly increase after mild winters and damp summers

To control: Slug pellets made of metaldehyde are permitted for use in organic gardening and can be broadcast over potato crops to control against slugs. Other safe control options include wool pellets and slug defence gels. A popular biological control is Nemaslug which is a parasitic worm that attacks and kills slugs

Wireworms: The tiny larvae of the Click Beetle are another pest of potatoes. Their symptoms can be recognised by a series of narrow (3mm wide) tunnels which bore through the tubers. The larvae can persist in the soil for 5 years as they grow larger and feed on potatoes and other bulbs over the years

To control: Chemical controls include Calcium cyanamide and Mocap 20 GS while SuperNemos provides biological control. The best control of wireworms is prevention and not to grow potatoes in ground that was recently grassland

Leather Jackets: These are the larval stage of the daddy long legs. While the adult is quite harmless, the young larvae will feed on the roots of vegetables, grasses & greenhouse plants. They can be a pest of potatoes

To control: Cypermethrin based pesticides are an effective control method for leather jackets

Black Scurf: Caused by a fungus which also leads to damping off in seedlings, Rhizoctonia Solani can survive in soils for many years and will lead to black scurf tubers. The disease is mainly recognisable as stunted plant growth. When the tuber are inspected you will notice a speckled black appearance that can easily be brushed off and will have no other effect on the tuber itself

To Control; Chemical options include pencycuron (Monceren) or Azoxystrobin (Amistar). But general good practice including crop rotation, good draining & airflow around crops will all help to protect your crops from Rhizoctonia Solani

Blackleg & Soft Rot: Caused by bacteria which affect potato plants in two ways and is most common in wet soils & damp conditions. The first signs of blackleg can appear in late June and is the yellowing & curling of foliage eventually leading to a blackening of lower stems at soil level. Later in the season the tuber are affected leading to the rotting of the tuber. This rot may not set in until after harvest but can continue to rot potatoes when in storage

To Control; There is no chemical control but good seed potato selection is your best chance at avoiding attacks. Most resistant varieties include: Pixie, Brodick, Kestrel and Saxon

Good practise includes crop rotation and checking crops regularly and removing and disposing of infected plants early. Ensure your soil has good drainage and when storing your potatoes that have been effected by the disease ensure good ventilation

Common Scab: This is another bacteria which affects the tuber, in this case the tubers can develop scaly outer surface. Disease occurs on potatoes on dry, sandy soils in dry and warm conditions. The scab, while unsightly has no effect on the quality, size or taste of the tuber

To control. No known chemical control but soil irrigation is can prevent infection. Avoid allowing soil drying out in summer months. Also choose resistant seed potatoes such as Accent, Arran Pilot, Juliette, Golden Wonder, King Edward, Pentland Crown and Pentland Javelin


There is an excellent selection of seed potatoes at the The Garden Shop. They have 1st earlies, 2nd earlies and main crops, some of which are blight resistant.

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