Diseases of potato (
Blackleg
Blackleg of potato is caused by Erwinia carotovora. The stems of infected plants are black and rotted (photo 1), and plants are stunted and usually wilt and eventually die (photo 2). The bacteria are on the surface or inside the seed piece. Cool, wet soils favor bacterial growth, and when temperatures increase, plants wilt rapidly. E. carotovora may persist for long periods of time in infected plant debris.
Blackleg is controlled by (1) using clean, certified, well healed seed pieces; (2) using clean planting equipment; (3) treating tubers with fungicides to reduce fungal infections that increase incidence of bacterial decay; (4) planting into well drained soil; and (4) avoiding excessive irrigation. It is important to prevent wounding seed pieces when planting. When symptoms appear, rogue infected plants if possible, being careful to take out all tubers.
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February 10, 2003