Frost and Botrytis risk from May 23rd to June 1st

Possible Frost

There were possible frost conditions in most fields from Saturday May 23rd to 24th and Sunday May 31st to June 1st.  Some fields also had frost conditions Sunday May 24th to Monday May 25th.  Temperatures below 30F can cause some damage but temperatures below 28F are associated with yield loss.   The table below shows the possible frost conditions with length of time when temperatures were below 35F and the lowest temperature recorded at each weather station.   I have chosen to report temperatures below 35F since there will have been colder or warmer areas around the weather station.

Possible Botrytis

There was also the risk of Botrytis infection with wet conditions over the past few nights.  Fields experienced one to three nights of possible Botrytis infection conditions if there already were Botrytis infections in the field to cause further infections.  Botrytis is not a  yearly problem in most Maine blueberry fields.  Botrytis can destroy blossoms and causes more damage with warmer conditions after  infection. Botrytis symptoms are dead blossoms with black hairs sticking out.  Blossoms can also be killed by mummy berry or cold temperatures.

The table below shows the possible frost conditions with length of time when temperatures were below 35F and the lowest temperature recorded. The Botrytis risk shows level of risk of infection, if Botrytis was already in a field, over the past week.

Location Frost May 23 to May 24  Frost May 24 to May 25 Frost May 31 to June 1 Botrytis risk May 27 to May 30 
Brunswick 8.5hr, 23.5F 7hr,  27.5F 5hr, 20.3F moderate
Waldoboro 3hr, 34.2F not below 35F 7hr, 29.7F moderate
West Rockport 1hr, 34.4F not below 35F none, 35.6F high
Hope/Appleton 6hr, 31.3F not below 35F 6.5hr, 30.9F high
Searsport not below 35F not below 35F 4hr,  33.2F high
Bluehill 6hr, 25.4F 7hr, 29.7F 5.5 hr, 27.7F low
Ellsworth/Hancock 2hr, 27.6F 1hr, 32.2F 5hr, 30.4F moderate
Aurora 7hr, 27.5F 4hr, 30.4F 7hr, 28.4F moderate
Eastbrook 4hr, 31.8F not below 35F 3.5hr 30.2F high
Gouldsboro 7hr, 30.9F 7.5hr, 30.6F 1hr, 34.3F high
Deblois/Airport 8.5hr, 22.9F 6hr, 26.6F 3hr, 29.4F high
Montegail 7hr, 27.6F 6hr, 31F 3hr, 28.3F high
Jonesboro 2hr, 33F not below 35F 3hr , 30F moderate
Whiting Probably, data missing overnight probably,

data missing

high
Crawford/Love Lake 1hr, 33.7F not below 35F 2hr, 32.1F moderate

Please let me know if you have any questions, Seanna Annis.