Recent warmer, damp weather has led blueberry growers in the southern region of Georgia to initiate sprays for mummy berry disease. According to the mummy berry model developed by Dr. Harald Scherm (UGA), there is a HIGH RISK for mummy berry disease initiation in southern Georgia as of February 17th, 2020. Growers who haven’t already done so are reminded to initiate sprays for mummy berry at this time to protect vulnerable blueberries (especially rabbiteye varieties that have reached green tip or early bloom).
Epidemics of mummy berry disease are set-up by the synchronized release of fungal ascospores and the emergence of green leaves in blueberries, which leads to subsequent leaf strikes. Since the fungus that causes the epidemic has similar chill-hour requirements for germination to the chill-hour requirements for native blueberry species, this means that ascospore release is typically synchronized with leaf development in rabbiteye blueberries in southern Georgia. Infections typically occur when rabbiteye varieties reach green tip or early bloom (whichever comes first). Regarding southern highbush varieties, if the leaf tissue is at green tip or early emergence, it can be infected with mummy berry as well; however, prior work has not confirmed mummy berry on southern highbush varieties in Georgia, since most of the time southern highbush varieties here escape the initial infections due to earlier plant development. By contrast, some highbush varieties elsewhere in the southeast can be severely affected, and if the correct environmental conditions occur on southern highbush varieties in Georgia, it should be assumed that these can likely develop mummy berry as well.
For management of mummy berry on rabbiteye blueberries, fungicides with activity against mummy berry should be applied starting at green tip or early bloom, whichever comes first. Additional information on fungicides which are available for management of mummy berry can be found in the Southeast Regional Blueberry Integrated Management Guide at www.smallfruits.org.