Mummy Berry Forecast for Monday April 27 to Wednesday April 29th

For Knox, Lincoln, Waldo and southwestern Hancock.
Union, Rockport, Camden area.
There are still active mummy berry cups in fields in these areas. Most plants are likely susceptible to the fungus now.

Belfast, Orland areas
Mummy berry cups are now active in your area. And if you have an early or particularly wet field, they may have been active by yesterday (Sunday April 26th). Most plants are close to or are susceptible by now. IF your plants are susceptible, more than 40% of stems had flower buds at the crown stage (please see post on Monday April 20th on how to evaluate this).


Overall forecast for Knox, Lincoln, Waldo, southwestern Hancock
There was little chance of an infection period within the last 3 days, since few fields were likely to have rain longer than 6 hours (the minimal length of plant wetness required to get infection at 65 F). IF your field had FOG you might have had an infection period. Please look at the chart in Factsheet #217 to check the length of time for plant wetness and temperature during that period.

There is a chance of infection periods sometime within Monday night through to Wednesday morning, depending upon whether you have fog or rain in your field and the temperature. The chart below show the plant wetness up to 65 F. At 72 to 80 F, which is forecasted for some areas Tuesday, the fungus only needs 3.5 hours of plant wetness to get infect the plants.
You will need to keep track of the approximate length of time of continuous rain and fog in your area and the temperature during the rain and fog to tell whether your field has had an infection period.
IF your plants are susceptible, more than 40% of stems had flower buds at the crown stage (please see previous post on how to evaluate this), AND you have had mummy berry disease in that field before, then the fungus could have infected your plants.

To control this disease you should apply fungicide within 72 hours of the START of the rain/fog period in your field. For example if the rain started in your area at 5 am on Tuesday you have until 5 am on Friday of this week to apply fungicide to kill off the infection and protect your plants.

Remember whether infection did occur in your field will depend upon 1) how far along the plants are in your field, 2) the actual temperature during, and length of time of rain or rain and fog in your field, and 3) of course, have you had mummy berry disease in your field in previous years .

Please check Factsheet #217 at the Wild Blueberry extension site (http://wildblueberries.maine.edu) for more information on the chance of infection depending upon temperature and length of leaf wetness. Please see Factsheet #219 for recommended disease control methods.