While mummy berry has become less common, there has been a resurgence of the disease in recent years that makes the curse of mummy berry much more serious. Mummy berry is caused by the fungus Moniliniavaccinii-corymbosi. The fungus kills young, vegetative shoots and can also infect fruit making them inedible.Additionally, losing young shoots to mummy berry can cause a reduction in yield the following year.
Mummy berry gets its name from the infected fruit which mummifies and falls off the bush every year.These mummies overwinter on the ground and serve as the source of primary inoculum for the following spring. In the spring, once the weather starts to warm up, the mummies form apothecia which are small cup-shaped mushroom-like bodies that are filled with ascospores. Ascospores are what cause the primary infections on young leaf tissue. Without the leaf tissue, infection cannot occur.
Mummy Berries
Mummies look like tiny black pumpkins, smaller than a penny, and are often covered with leaf litter or partially embedded in the soil. You will have to get down and look very closely for these, they are easy to miss.Scouting hotspots and places you have historically had problems with first is always a good idea. Hotspots for mummy berry are often near forested areas and wet parts of the farm.
Removing and disposing of the mummies or burying them at least two inches deep with mulch reduces potential inoculum and helps fight mummy berry. Unfortunately, we often need to revert to fungicide applications to control this disease. Typically, fungicides belonging to FRAC code 3 are usually the most effective. There are several biologically based fungicides a grower might consider using near bloom to protect pollinators that have been effective in recent research trials.
Mummy berry with disease
The first symptom of mummy berry disease in the spring is the wilting of young leaves and shoots accompanied by a browning of the midribs and lateral leaf veins. Browning caused by mummy berry occursin an oak-leaf pattern along the main leaf vein. Eventually, the entire shoot dies and looks like a shepherd’s-crook. Shoot strike is often used to describe blighted shoots. When humidity is high, tan to gray powdery spores can develop on the infected shoots.
Occasionally, individual flowers whole flower clusters may also become blighted. Flower strikes are less common than shoot strikes and may be confused with blossom blight caused by other fungi. However, the layer of gray spores on the stem of the flower is a key diagnostic characteristic of mummy berry. The blightedtissues eventually dry up and fall off the blueberry bush.
If you find blighted leaves or flowers and are not sure if it is caused by mummy berry, you can send in a sampleyour local lab for testing.