Mummy Berries: Not a Delicious Frosted Breakfast Cereal

Mummy berry is a disease of blueberry plants caused by the fungus Monilinia vaccinii-corymbosi. The fungus overwinters in mummified fruit [called mummies] on the ground . . . The mummies form cup or globe-shaped structures called apothecia.  Apothecia produce spores that infect young tissue and cause rapid wilting. This is called leaf and twig blight, or bud and twig blight. These symptoms are difficult to distinguish from frost injury. These first infections form more spores, which are spread by rain, wind and bees to blossoms and other young tissue. The fungus infects and invades the developing fruit. The fruit becomes malformed looking like a pumpkin, and turns salmon or grey by midsummer . . . By fall, these fruit drop to the ground where they turn into mummies ready to produce apothecia the next spring.” [1]

Guess who’s got it?  Me!

I bought two blueberry bushes this spring, hoping to house them in large containers on either side of the stairs I’m putting in the front garden to try to funnel the rampant, unconcerned foot traffic of the entire neighborhood (including my own husband) into one path through the bed.  One bush was ‘Jersey’ and one was ‘Sunshine Blue’.  I picked them because they are both compact.  Neither is supposed to exceed 4 feet by 4 feet when mature.  Had I been paying more attention I would have gotten two ‘Sunshine Blue’s, which are evergreen, and passed over the deciduous ‘Jersey’ so that my stairway accent will be symmetrical.  And had I known that ‘Jersey’ was going to come down with mummy berry I would never have bought it.

Given that mummy berry is caused by a fungus, and I hate to admit defeat in the garden, my first online search was for effective organic fungicides for treating mummy berry.  The two I have in my arsenal, Neem oil and Bordeaux mixture, are both ineffective, as I learned. [2] [3]  The only controls that seem to have any effect are pruning by fire and heavy mulching to prevent the transmission of spores in spring.[3]  After hearing the rather poor statistics on the “success” of these methods I abandoned hope.  Incidentally, I found a ranking of 134 blueberry varieties ranked by increasing susceptibility to mummy berry: ‘Sunshine Blue’ came in at 58 and ‘Jersey’ at 83. [4]

Oh, darn, I have to go back to the nursery . . .
– Amanda

UPDATE: I have since taken another look at my diseased blueberry and found that it is, in fact, a ‘Northblue’ and not a ‘Jersey’.  Northblue is rated at 131 out of 134, making it one of the most resistant varieties.  Just goes to show you that ‘resistant’ does not mean ‘immune’.

[1] “Integrated Management of Blueberry Diseases: Fruit Diseases”.  http://www.oardc.ohio-state.edu/fruitpathology/organic/Blueberry/fruit.html

[2] Grubinger, Vern. “Mummy Berry Disease of Bluberry.” http://www.uvm.edu/vtvegandberry/factsheets/mummyberry.html
[3] Drummond, Frank, et al.  “Organic Management – 304 – Organic Wild Blueberry Production.” Fact Sheet No. 304, UMaine No. 2029.  http://umaine.edu/blueberries/factsheets/organic/304-organic-wild-blueberry-production/
[4] Ehlenfeldt, Mark K., et al.  “Ranking Cultivated Blueberry for Mummy Berry Blight and Fruit Infection Incidence Using Resampling and Principal Components Analysis.” Hortscience Vol. 45(8) August 2010. http://ddr.nal.usda.gov/bitstream/10113/46609/1/IND44438151.pdf
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