Powdery
mildew
Microsphaera
vaccinii (fungus)
Annemiek Schilder,
MSU Plant Pathology
Bill
Cline, NCSU Plant
Pathology |
| Powdery mildew can be found in most blueberry
plantings, but damage tends to be slight. |
 |
 |
| Early and late symptoms of powdery mildew on upper leaf surfaces. |
|
Symptoms
Symptoms on blueberry leaves usually do not develop
until midsummer. The leaves show light green, yellow or reddish
areas and puckering. Water-soaked spotting is visible on leaf
undersides. White, powdery growth may develop on the upper leaf
surfaces. In severe cases, plants may defoliate.
|
Disease cycle
At the end of summer, yellow to black fruiting bodies
(cleistothecia) form on infected leaves. Airborne spores released
by cleistothecia in the spring infect young leaves. The mycelium
is superficial and penetrates only the epidermis. |
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 |
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| Water-soaked, radiating spots on underside of leaf. |
Cleistothecia (yellow specks) on upper leaf surface. |
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Secondary spores are produced on the leaves and dispersed by wind throughout the summer. High temperatures and humidity promote disease development.
Management
Plant resistant cultivars; reduce humidity in the
planting. Fungicides are not recommended unless the disease is
severe. |
