Cooperative Extension: Maine Wild Blueberries

6.06.12 Symptoms you may be Seeing in your Field

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By Seanna Annis

There are a number of different problems you may be seeing symptoms of in your crop field. Please see below for some pictures of common problems at this time of the year.

Frost Damage

• All flower clusters on stem typically are affected
• Closed flowers not affected as much
• Leaves can be damaged, but typically only tender tissue (right picture)
• Key symptom: Often all flower clusters on a stem are affected

Mummy Berry Blight

• Only some flower and some leaf clusters on stem typically are infected. Some very susceptible clones may have stems with all of the leaves and flowers affected.
• Open and closed flowers will show symptoms
• Only some leaves will be infected, look dead and have the typical “crook” shape
• Key Symptom: Gray powdery spores (in yellow circles) at base of affected flowers and leaves

Botrytis Blossom Blight

• 

  Only some flower clusters on a stem will be affected

• Mostly affects  almost open and open flowers
• Leaves can also show disease symptoms, but very rarely and usually when touched by infected flowers.
• Key Symptom: black hairs, some with gray tips, (in yellow circles) extend off of  infected flowers and leaves

Red Leaf Disease

• Starts to be visible in crop fields by early bloom, later in June in prune fields. Isolated patches of stems are affected. Leavers are bright red (sometimes not the whole leaf), and leaf may be slightly thickened.
• About the end of June, white spores are produced on the underside of infected leaves.
• Key Symptom: Bright red leaves, with color not just at  tips of leaf. Slightly thickened leaves, late4r white underside of affected leaves.