• Worldwide distribution. In Australia, New Zealand, New Caledonia, Papua New Guinea.
• A devasting disease of potato; also affecting tomatoes, eggplants, and others. Entry through roots: leaves rapidly turn yellowish and wilt; stems show browning and ooze from vascular areas; plants collapse and die. Ooze too from ‘eyes’ (buds) of tubers.
• Spread: short distances by run-off water; longer distances by movement of infected tubers, soil on machinery, shoes. Possibly insects. Survival: in soil up to 2 years; on volunteers, weeds, roots of non-hosts.
• Biosecurity: protocols needed to respond to a breach, and a plan should eradication fail.
• Cultural control: use only certified seed; avoid cutting tubers; avoid land where diseases previously occurred, or have 2-3 year (preferably 4) rotation with unrelated crops (cereals, sweet potato, cabbages, onions); improve drainage using ridges or raised beds; rogue disease plants; clean machinery, tools, footwear after working in infested fields; collect debris after harvest and burn.
• Chemical control: not appropriate for this disease.

Brown rot of potato. It is also known as bacterial wilt of potato.

Ralstonia solanacearum Race 3 biovar 2 (R3bv2). Other names are: Bacillus solanacearum, Burkholderia solanacearum, and Pseudomonas solanacearum. There are five races of Ralstonia solanacearum: Race 1 has a host range of over 50 plant families (200 plant species), including chilli, capsicum, peanut, and Solanum species (but more rarely on potato); race 2 mostly affects banana and Heliconia; Race 3, geranium and potato; Race 4, ginger; and Race 5, mulberry.

An alternative system based on carbohydrate substrates divides strains into five biovars, with e.g., Race 1 corresponding to biovars 1, 3 and 4, and Race 3 to biovar 2, and Race 5 to biovar 5.

However, under a revised classification system (2005), and based on DNA sequencing, Ralstonia solanacearum has been divided into four groups, reflecting geography (phylotypes), and further by genetic sequence of an important gene (sequevars). By this method potato brown rot is Phylotype II, sequevars 1&2.