Blackleg and Tuber Soft Rot
Pathogen: Erwinia carotovora var. atroseptica, E. carotovora
var. carotovora
Symptoms
 Blackening
and rotting at the base of the stem; hollowing above the blackened
area; stunting and yellowing of the foliage, and upward curling
of leaflets. As the disease progresses, the plant wilts and
dies. In the tubers, soft black rot begins to develop, usually
from the stolon, and develops until the tuber disintegrates.
The ability of the tuber to bud is impaired. There is a characteristic
foul odor. Rot may also develop on the sides of the tuber
lenticels and wounds.
Damage
Plant death and substantial yield loss. Rotting develops
in the soil or during storage. Infestation may be latent,
and be expressed after planting or during storage.
Conditions for Development
The mother-tuber is the main source of contamination. Cutting
of infested seed-tubers can intensify the distribution of
the disease in the field. The bacteria survive in plant residues
remaining in the soil, are transmitted by free water, and
can contaminate neighboring plants. The disease penetrates
through cracks in the tubers and lenticels. The disease in
the daughter tubers continues to develop in the soil, under
conditions of high humidity, and in poorly-ventilated storage
areas.
Control
Management: Optimal drainage and aeration of the soil; avoidance
of over-watering; removing affected plants from the field
and burning them; control of seed production. Sterilization
of tools, sorting machinery, etc. Well ventilated storage,
and thorough drying of tubers after washing. Aerial Stem
Rot
Black Dot, Colletotrichum
coccodes
Blackleg and Tuber Soft Rot
Black Scurf, Rhizoctonia Canker
Common Scab, Streptomyces scabies
Early Blight, Alternaria solani
Deep Pitted Scab, Streptomyces spp
Leak, Pythium ultimum
PLRV, Potato Leafroll Virus
Powdery Scab, Spongospora subterranea
PVX, Potato Virus X
PVY, Potato Virus Y
Verticillium Wilt, Verticillium dahliae
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