Mummy berry disease

Taxonomy and pathogen type: Monilinia vaccinii-corymbosi is an ascomycete fungus belonging to the Sclerotiniaceae family. It is a highly specialized plant pathogen that serves as the primary cause of the destructive "mummy berry" disease affecting highbush blueberries.

Diseases and host plants: The pathogen primarily targets species within the Vaccinium genus. It induces a dual-stage disease cycle: the primary phase causes blight and wilting of young shoots and leaves, while the secondary phase results in the infection of fruit, causing them to turn into hard, greyish mummies.

Biology and life cycle: The fungus overwinters as sclerotia in fallen berries on the orchard floor. In early spring, during blueberry bud break, these sclerotia produce apothecia that release ascospores. These spores infect succulent shoots, leading to the production of conidia, which are then spread by wind and insects to blossoms to infect the developing fruit.

Conditions and impact: Disease development is heavily favored by cool, wet spring weather coinciding with the phenological stages of blueberry development. The economic impact is severe, as infection can lead to massive yield losses and a reduction in the overall vigor of the blueberry bushes due to the blight damage.

Protection and control measures: Effective management of mummy berry requires an integrated pest management (IPM) approach:

• Cultural control: Removing infected berries from the orchard floor and burying sclerotia through deep cultivation.
• Covering the ground with mulch (like wood chips) to physically block spore release from sclerotia.
• Chemical control: Applying protective fungicides at critical times, specifically during the bud break and flowering stages.
• Monitoring the orchard environment to predict infection windows based on weather patterns.