Mummy berry disease

Mummy berry disease, caused by the fungus Monilinia baccarum, is one of the most economically significant fungal diseases affecting blueberry cultivation. This pathogen belongs to the Sclerotiniaceae family and is widespread in major blueberry-growing regions worldwide, posing a constant threat to berry productivity.

The host range is primarily limited to species within the Vaccinium genus. The disease affects the plant in two distinct phases: the primary infection, which targets emerging shoots and leaves, and the secondary infection, which targets the blossoms and eventually the developing fruit, turning it into a shriveled 'mummy'.

Early symptoms appear as water-soaked lesions on young leaves and succulent shoots, which quickly turn brown or black and die back. During bloom, the fungus colonizes the flowers, leading to blossom blight. As the fruit develops, the infected berries become hard, light-tan to greyish, and eventually drop prematurely to the ground.

The life cycle is tightly synchronized with the host's development. In early spring, overwintering sclerotia ('mummies') in the soil produce small, trumpet-shaped structures called apothecia. These release ascospores into the air, which are carried by wind to the young emerging blueberry tissues during wet weather conditions.

To effectively control Monilinia baccarum, growers should employ an integrated pest management strategy. Key practices involve:

• Sanitation: removing and destroying infected berries and plant debris after harvest.
• Cultivation: burying sclerotia by tilling or covering the ground with fresh mulch.
• Chemical control: applying fungicides during the green tip stage and bloom period.
• Monitoring: using environmental sensors to predict infection periods based on humidity and temperature.