Cooperative Extension: Maine Wild Blueberries

Mummy berry season is starting to end in some areas.   If the cups are finished in your area, there is no advantage for spraying fungicides for mummy berry control at this time.  The secondary Monilinia spores on the dead tissues (mummy berry symptoms) are carried by pollinators to the healthy flowers to infect the fruit and eventually produce the “mummy berry” looking infected fruit.  By the time you see the dead leaves and flowers from mummy berry blight, the pollinators will have already found and transferred a lot of the spores.  A fungicide spray during bloom may affect bee pollination by making the plant less attractive in smell to the bees, or could have other effects upon the bees.

There were still cups in fields in Midcoast on Monday but they were drying up on Wednesday and are probably finishing up by now.  From May 6th to May 10th, the fields with working weather stations had conditions for one to two Monilinia infection events with one on May 5th evening (7 to 9pm) to May 6th morning and another starting about May 8th at 12pm to May 9th.  . There may not have been any actual infection by Monilinia in fields in this region if the cups had dried up.

There are still lots of mummy berry cups and pinheads in fields at Deblois, Jonesboro and Whiting today (Friday May 10).  From May 6th to May 10th, the fields with weather stations had conditions for from one to three Monilinia infection events. It is likely the cups will still be around on Monday night when more rain is forecast.

There have also been some very cold temperatures overnight on May 10th in Aurora (temperature below 28F for 6 hours) and Deblois (off and on below 28F for about three to four hours).  If you have fields in those regions, your plants may also have been affected by the cold.