Cooperative Extension: Maine Wild Blueberries

5.10.20 Possible mummy berry infection period and cold temperatures May 8 to 10th

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All weather stations experienced wet conditions and cold temperatures from May 8th to May 10th.  Following our disease estimates, some fields may have experienced conditions that caused Monilinia infection.  I do not know if infection can occur with snow on the plants.  However, there is a good chance there was infection even with the cold temperatures considering how long the leaf wetness occurred in many areas.   Previous research has shown that cold temperatures, approximately 32F and below, can make the infections that do occur cause increased damage.   In many fields, cold temperatures occurred during the wetness on the plants and in some fields on the night of May 9th to 10th too.  The table below shows which weather station locations had possible infection periods, according to our disease estimates, and the periods of cold temperatures seen over this weekend.

It looks like we will be getting more wet weather on Monday through Tuesday which may cause more Monilinia infections. If there is cold  damage to the plants, that may also increase damage from Monilinia infections occurring Monday.

If you had applied fungicides approximately 7 days before, May 1st or later, then your plants were probably protected over this weekend.