Cooperative Extension: Maine Wild Blueberries

5.14.14 Mummy Berry Infections, May 14 and May 15

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Knox, Lincoln, Waldo Counties

Growers reported only finding dried up cups on Tuesday, May 13 in their mummy berry plots.  I do not think the cups were done at that time in most fields since there is a range of when cups develop and I expect there were lingering cups around.  There were infection periods in some fields over Wednesday night into Thursday, please see the chart below.  I expect most cups will be done by Friday, May 16 evening with this warm weather.   I don’t expect most areas to have infection periods occurring this weekend.  If you have a wet, late field you may still experience mummy berry infections this weekend.

Hancock and Washington Counties

There were still active cups and some pinheads found in fields in the barrens on Tuesday. Infection periods did occur in these areas over Thursday night.  I expect the cups will be around this weekend in these areas. I expect the Blue Hill and  Ellsworth area will also be finishing up with cups this weekend.

Infection Periods and Fungicide Applications

In those areas where there was an infection period starting Wed. May 14, if you have applied fungicide on or after Wednesday, May 7 your plants were protected and you have until the evening of  Saturday, May 17,  in most areas to apply fungicides to kill any infection.

In those areas where there was an infection period starting Thursday, May 15, if you have applied fungicide on or after Thursday, May 8 your plants were protected and you have until the evening of Sunday, May 18,  in most areas to apply fungicides to kill any infection.

If you would be applying a second application of propiconazole, it would be a good idea to switch to a different fungicide with a different mode of action to help prevent resistance to propiconazole developing in your field (Please see the 2014 Maine Wild Blueberry Pesticide Chart, Fungicides (PDF)).  Other fungicides should be applied as protectants and before infection periods occur.