UGA Blueberry Blog

Mummy Berry Warning

I have reports from the southern region of the state which would indicate that leaves are starting to emerge on rabbiteye blueberries.  This is truly an early leaf emergence for rabbiteyes, likely due to the exceptionally warm weather we are now experiencing.  Blooms may not be far behind.  As such, it begs the question as to whether or not mummy berry will be an issue (leaf infections at green-tip) at this time.  In the past readings of the mummy berry model, emergence of green leaves in rabbiteye blueberries has been synchronized with the release of ascospores and subsequent leaf strikes.  This sets up the epidemic.

Dr. Harald Scherm has determined the mummy berry potential (germination  and development of the apothecia); based on his model, 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 if temperatures continue to be warm and we have rainfall.  Mummy berry is very well tied to the initiation of budbreak and bloom, especially in rabbiteyes.  With rabbiteye green tip and/or bloom development starting this week in some varieties, producers need to spray mummy berry active fungicides in earnest. 

Another question comes up relative the southern highbush blueberries.  If the leaf tissue is at green tip or early emergence, it can be infected on southern highbush as well.  I have said this before, but to date, I have not observed or confirmed mummy berry on southern highbush varieties in Georgia.  However, based on communication with Bill Cline in North Carolina, some of the same varieties are “hammered” with mummy berry in his state.  If the correct environmental conditions occur on southern highbush varieties, my assumption would be that we will have mummy berry.  Most if not all of the time, the southern highbush varieties escape the initial infections in Georgia.  However, would I count on that?  The answer is no.  John Ed Smith (MBG) reported today that, “We have early bloom and leaf tip on Emerald, Farthing, Rebel, and Sweet Crisp.  Particularly those fields that were treated with Dormex.  We also have early flowers and leaf tip on Premier, Vernon, Austin and Alapaha.”  If the tissue is in a susceptible stage, infection can occur.  The good news is that we do not have frost-damaged tissue and the forecast does not indicate any frost for a while; frosts will increase the infection potential of mummy berry.  It has also been relatively dry as of late, so I hope that will help to reduce mushroom development and infections a bit.  With that said, rainfall is in the forecast for the next few days.

Bottom line.  Producers should initiate mummy berry sprays, and any blueberries are susceptible if they are in the correct stage (green tip and early-bloom [bud break] and continuing through bloom).  Though this means we will be starting fungicide applications earlier than I can remember, that is the call at this point.  Strange weather does have an impact on blueberries, as well as their pathogens.  We simply have to adjust. 

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Phil Brannen

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.