Damage to Blueberry Flowers - Is it Frost or Disease?

There can be multiple reasons why you see brown flowers on your plants. One of these is frost damage, and the others are infection by Mummy berry blight OR infection by Botrytis blossom blight. It is highly unlikely we have had the conditions for blossom blight in most fields. Long periods of wetness on almost open to fully open flowers is required for infection by the Botrytis fungus. Before applying fungicide to protect your plants from Blossom blight make sure you know what is the cause of your browning flowers.
Frost damage to flowers has occurred in the last week to some fields.
This is also the time that flower infections by mummy berry blight will be seen in fields.
Botrytis blossom blight can be scouted for on early blooming clones.

Please see the pictures and notes below, to determine what is the cause of your problem. Disease recommendations are in the "Disease Control Guide for Wild Blueberries (revised 2010) Publication 219.

Frost Damage to Flowers
- All flowers clusters on a stem will be affected

- Closed flowers are not affected as much

- Leaves are not affected

- NOTE - You will only see browning of flowers that are almost open or fully open.



Mummy Berry Blight of Flowers
- Only some flower clusters on a stem will be affected

- Open and closed flowers are affected

- Leaves will also show symptoms of the disease

- NOTE - Gray powder (spores) at base of flowers



Botrytis Blossom Blight
- Only some flower clusters on a stem will be affected

- Only almost open and fully open flowers affected

- Leaves can also show disease symptoms


- NOTE - black hairs (may have gray tips - spores) extend off of affected flowers