Plant pathogenic bacteria cause a number of important potato diseases: Potato brown disease is caused by Ralstonia solanacearum. Initial symptoms in the field are wilting of the upper leaves followed by permanent wilting and death of the plant. Browndiscolouration of the vascular tissues extends upwards from the stem base. In tubers, initial browning of the vascular ring at the stolon end eventually extends and becomes necrotic with secondary rot development. Cut stems and tubers exude a creamy white bacterial slime from the vascular tissues. Bacterial ooze may exude from the eyes and heel end of affected tubers.
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