North Carolina Plant Disease and Insect Clinic
Plant Disease Fact Sheets

Mummy berry of blueberry

Overwintering mummies are blueberry sized, pumpkin-shaped, and hollow


Apothecia are cup-shaped mushrooms that emerge from old overwintering mummies and release spores in spring


Early stage of primary or shoot strike phase. Note wilting leaf with veins turning brown.


blighted shoot with masses of gray spores that will spread to flowers and infect fruit.


Severe shoot blight symptoms on rabbiteye blueberry.


An infected, ripening berry cut open to show white fungal growth inside.


Salmon-colored infected berries compared to healthy blue fruit.


Mummies on the ground under a heavily infected bush.


Mummy berry is a plant disease caused by the fungus Monilinia vaccinii-corymbosi.  The fungus overwinters on the ground, and in Spring produces a cup-shaped mushroom that releases spores.  These spores infect and kill emerging leaf shoots, causing the shoot blight (primary) phase of the disease.  Blighted shoots then produce a second type of spore that is carried by insects to the flowers, where fruit (secondary) infection takes place.  The end result is mummies, infected berries that do not turn blue, but instead turn pale pink or salmon-colored and fall to the ground.


Symptoms and Disease Development

Emergence from dormancy -- In early Spring, small, stalked, brown, cup-shaped mushrooms called apothecia are produced from old mummies left on the ground from the previous year. In southeastern North Carolina, overwintered mummies break dormancy around the first week in February and develop mature apothecia about one month later. The fungus is synchronized with the host, and emerges when the first new leaf and flower shoots are appearing on blueberry plants.

Primary infection -- spores (ascospores) produced by the apothecia on the ground are liberated during cool, wet weather and are carried by air currents to the young emerging leaf and flower shoots. These spores infect and blight the young shoots, and secondary spores (conidia) are produced in great abundance on the blighted leaves. This primary or shoot blight phase can be quite damaging, especially on rabbiteye blueberries where sometimes the majority of the shoots on the bush are blighted, giving the plant a scorched appearance.

Secondary infection -- the secondary or fruit infection stage occurs when spores (conidia) released from the primary infections described above are carried by insects to open flowers, where the spores germinate and infect the ovules of the developing berry. Infected berries appear normal until ripening begins, at which time they become light pink or salmon color rather than normal blue, and drop to the ground. These infected fruit, if left on the ground, form overwintering mummies that provide a source of disease the following year.


Methods of Controlling Mummy Berry


Sanitation
-- remove or bury infected fruit to prevent overwintering of the fungus. The fungus overwinters solely as infected mummies on the soil surface. Raking or hand collecting mummies can remove much of this inoculum from small plantings. Mummies on the ground are most visible immediately after harvest, but are harder to see in the fall, so hand-removal or raking should be done immediately after harvest. Not all old fruit is infected -- learn to distinguish the typical pale, fungus-filled appearance of fresh mummies, and the ridged, pumpkin-like shape of mummies in winter, as shown in the accompanying images.


Cultural Control
-- Mummies buried an inch or more in depth will not germinate. Soil or mulch applied under the bushes any time after harvest (but before Spring of the following year) will prevent mummies from germinating and infecting in subsequent seasons.


Resistance
  -- All blueberries are susceptible to mummy berry, but some tend to have fewer infections and are considered resistant to the disease. Resistant cultivars include certain southern highbush (Star, O'Neal, Legacy) rabbiteye (Premier, Powderblue) and northern highbush (Duke, Bluecrop, Patriot).


Fungicides
-- Both protectant and systemic fungicides are available for control of mummy berry disease. Fungicides applied during shoot emergence and especially during bloom can be quite effective in controlling this disease. Sprays should be applied every 7 to 14 days beginning when the green tips of emerging leaf shoots first become visible (or when the first flowers clusters begin to emerge, whichever comes first) and continuing through bloom. Once the bloom period is over and all flowers are gone, no further infection will occur. For the most up-to-date fungicide recommendations, consult with your county extension agent or the NC Agricultural Chemicals Manual.