Biology
Soft rot and blackleg are both caused by bacteria. The soft rot symptoms typically appear on tubers. The small to large circular lesions are sunken, tan or brown, water-soaked areas on the tuber surface. The affected internal tissues are white to tan and develop a soft, almost odorless rot. An amber liquid may ooze from rotting areas. Blackleg symptoms are generally limited to leaves and stems. Leaves curl upward and turn yellow. Soft, light brown to black lesions develop at the base of stems and may spread into a black, slimy rot of tubers. In dry weather, the stem discoloration may be internal only. Under favorable conditions (warm, moist weather), plants wilt and die. The bacteria are carried in contaminated plant debris, water, soil, and seed pieces and are easily spread by splashing water, insects, and equipment.
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