Flowers
Frost during bloom may cause serious damage to developing flower buds and blooms. Once flower buds open, cold hardiness for the most part is lost. Temperatures of 28 F or lower may result in frost damage.
Fruit
Frost injury causes fruit to have a dark, shrunken appearance that readily distinguishes them from unaffected fruit. Severely damaged fruit appear hollow when cut in half. Frost or freeze injured fruit may drop to the ground prematurely before harvest. View pictures of mature frost damaged fruit.
Immature, green fruit is also susceptible to frost damage. Injury may cause water-soaked appearance on developing berries.
Leaves and shoots
Frost injury can cause shoot and tip dieback. These tissues are more vulnerable to the gray mold botrytis.
More information:
- Spring Freeze Injury (Michigan State)
- Using Sprinklers to Protect Blueberries from Spring Freezes (Michigan State)
- Using Your Sprinkler System to Protect Blueberries from Freezes (Michigan State)
- Blueberry Freeze Damage and Protection Measures (North Carolina State)
Use these resources if you need additional help with diagnosis and to find solutions to your problem.