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Mummy Berry Model Prediction

Dr. Harald Scherm has determined the mummy berry potential (germination and development of the apothecia); all southern Georgia blueberries that are showing either green tip or early bloom developmental stages are at high risk for mummy berry infection at this time and going forward. This is especially true as temperatures warm up next week and we have rainfall. If we can extrapolate the temperature information from Dr. Annemiek Schilder’s Michigan fact sheet on mummy berry (Schilder et al., 2008) to rabbiteyes, we do start to see a match again this year:

“Ascospore germination requires free water, and the optimum temperature for infection of susceptible tissue is 57°F. Developing vegetative buds become susceptible to infection when about 1/6th inch of green tissue is exposed. Flower buds become susceptible when the bud scales begin to separate. At 57°C with adequate moisture, germination and infection can occur within 4 hours; at 36°F, at least 10 hours of leaf wetness are required for infection. Blight symptoms appear about two weeks after infection. In lowbush blueberries, developing leaf and flower bud tissues are more susceptible to infection after exposure to freezing temperatures, and this susceptibility can last for up to 4 days after the frost event. This also appears to be the case in highbush blueberries.”

Mummy berry is very well tied to the initiation of budbreak and bloom, especially in rabbiteyes. With rabbiteye green tip and/or bloom development likely starting next week, producers need to be ready to spray mummy berry active fungicides in earnest.

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About Phil Brannen

Phil Brannen is a Professor in the Plant Pathology Department at the University of Georgia. He attended the University of Georgia for his undergraduate degree in Plant Protection and Pest Management, where he also received an M.S. in Plant Pathology, followed by a Ph.D. in Plant Pathology from Auburn University. He has extensive experience with disease management programs in numerous cropping systems. He serves as the extension fruit pathologist for Georgia – conducting research and technology transfer for multiple fruit commodities. His blueberry efforts are directed towards developing IPM practices to solve disease issues and technology transfer of disease-management methods to commercial blueberry producers. He also teaches the graduate level Field Pathology Course, team-teaches the IPM Course, coordinates the Viticulture and Enology in the Mediterranean Region Course (Cortona, Italy), and guest lectures in numerous other courses throughout the year.