Mummy
berry
Monilinia
vaccinii-corymbosi (fungus)
Annemiek Schilder,
MSU Plant Pathology
Bill
Cline, NCSU
Plant Pathology
|
Flower clusters with
gray spore masses. |
Mummy berry is an
important fungal disease of blueberries throughout the United
States and Canada.
Symptoms
The first symptom of shoot blight (shoot
strike) is browning along the major leaf veins. The leaves
wilt quickly and bend to resemble a shepherd's crook. A
light gray powdery layer of spores develops at the leaf
base. Flower strikes occur less frequently. |
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Infected green
berries appear healthy but cutting them open reveals a white
fungal growth in the locules. When berries start to ripen,
infected berries appear pinkish tan and slightly ridged. They
feel rubbery and contain a gray to black fungal mass inside.
Infected berries eventually become faded, shrivel up, and
fall to the ground. After the fruit skin has weathered off,
the berries look like tiny black pumpkins. |
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Disease cycle
The fungus overwinters in the mummified fruit on
the ground. In early spring, trumpet-shaped apothecia (3 to 10
mm in diameter) produced on the mummies eject windborne ascospores
that infect young shoots and flower clusters. |
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| The optimum temperature
for formation of apothecia and infection is 50 to 57ºF (10
to 14ºC). At least 12 hours of wetness is required for infection.
Frost may increase susceptibility of blueberry shoots to infection.
Conidia are produced on blighted shoots and flower clusters and
are carried to flowers by wind, rain, and insects (bees). The fungus
then colonizes the ovary of the developing fruit through the stigma.
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| Early
(left) and late (right) symptoms of shoot strike. |
Spores visible. |
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Management
Remove or destroy mummies; cover mummies
with soil or mulch – at least 2 inches (5 cm) thick; avoid
wet sites or improve drainage; remove escaped or wild blueberries
from vicinity; plant resistant cultivars; limit overhead irrigation
until petal fall; apply effective fungicides from green tip until
petal fall. |
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| Mummified berries
with immature (left) and mature apothecia in early spring. |
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For more details,
click here. |
