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How to Manage Pests
UC Pest Management Guidelines
Spinach
Stemphylium Leaf Spot
Pathogen: Stemphylium botryosum f. sp. spinacia
(Reviewed 11/05,
updated 11/05)
In this Guideline:
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SYMPTOMS
Initial symptoms of Stemphylium leaf spot on leaves consist of small
(0.13 to 0.25 inch diameter), circular to oval, gray‑green leaf spots. As
the disease progresses, leaf spots enlarge, remain circular to oval in shape,
and turn tan in color. Older spots coalesce, dry up, and become papery in
texture. Visual signs of fungal growth are generally absent from the spots;
hence this problem is readily differentiated from foliar diseases in which
purple growth (downy mildew), green spores (Cladosporium leaf spot), or
acervuli (anthracnose) develop within circular lesions. Overall, symptoms resemble
the tan, circular spots caused by pesticide or fertilizer damage. This pathogen
is seedborne.
MANAGEMENT
This disease was characterized for the first time in 1998 and there
is no information available on how the disease develops. This disease appears
to be of minor importance and no spray controls are recommended.
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UC IPM Pest Management Guidelines: Spinach
UC ANR Publication 3467
Diseases
S. T. Koike, UC Cooperative
Extension, Monterey Co.
M. LeStrange, UC Cooperative Extension, Tulare Co.
F. F. Laemmlen, UC Cooperative Extension, Santa Barbara Co.
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