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Common Scab

Streptomyces scabies


Actinomycete (closely related to a bacterium)


Potatoes, beetroot, radishes, carrots, turnips, swedes and a range of weed species.


Shallow and irregular blemishes on the tuber, occasionally with a raised appearance. Deep cracking and pits develop in severe cases.


The main source of the disease is infected soil. It exists as a free-living organism which infects tissue via lenticels (pores in the tuber surface) or wounds caused by machinery or pests. Infection occurs soon after tuber initiation and the plant responds by producing loose corky tissue which enlarges to form scabs as the tuber swells. It does not develop and spread in storage.

Favourable Factors

Dry, warm soil conditions and light alkaline soils.


A commonly occuring disease of potato tubers and although it may not affect their yield, it can reduce their market value because infected tubers are less attractive and it can lead to considerable peeling wastage.


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.

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