Brown rot is caused by the bacterium Ralstonia solanacearum. It prefers warm temperate regions, so it infests potato crops in the UK. The symptoms are wilting of the aerial parts of the plant after it has attacked the vascular bundles in the stem. These vascular areas are also present in the tubers and it is here that the disease is most noticeable. A brown ring is found if the tuber is cut in half; as the disease progresses the ring rots away completely, and a pale ooze may emerge from the "eyes" and heel of the tuber.
The infection is carried in seed potatoes and in water. Also contaminated potato waste should never be dumped where crops are to be grown or added to compost heaps. Any affected tubers left behind after gathering (groundkeepers) can carry it over to following seasons. Woody nightshade (Solanum dulcamara) can act as an alternative host so if the roots are near a waterway, the infection can contaminate the water. All tools and equipment should be thoroughly cleaned and disinfected to prevent carryover to other ground.
Potato Ring Rot shows almost identical symptoms.
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