POTATO
Symptoms
may appear at any plant age and include wilting and yellowing of leaves
and
stunting of plants. Disease may be
severe in young, succulent plants and may appear as rapid wilting of
leaves and
collapse of stems. Initially, only one
stem may wilt. If conditions are
optimal, all the leaves in a hill may wilt quickly but remain green. Stems may appear streaked as infected
vascular bundles become visible. Tuber
vascular tissue is usually a distinct grayish brown, and the
discoloration may
expand into the pith or cortex. Tuber
eyes turn grayish brown, and a sticky exudate may form at the eyes or
where the
stolon is attached to the tuber.
Eventually, infected tubers left in the ground will turn into a
slimy
mass surrounded by a thin layer of outer tissue and periderm (8).
|
|
| Potato tuber with brown rot. |
Potato plant showing wilting of one stem.
|
(Photos courtsey of J.
Elphinstone, Central Science Laboratory, DEFRA, UK)
|
Field
trial evaluating susceptible and resistant potato clones. Notice
the
severely wilted/stunted susceptible plants in the middle row. |
(Photo courtsey of C. Lopes,
EMBRAPA,
Brasilia, DF, Brazil)
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