The fungus overwinters in mummified berries. In favorable spring weather, ascospores are released from the brown cup-shaped apothecia and blown onto emerging blueberry leaves and stems. Symptoms include new leaves and shoots wilting and quickly turning brown. If wet humid conditions persist, a light gray, powdery mold develops on blighted tissue. In the second stage, conidia are produced on leaves and stems and blown onto flowers.
Bees then transfer conidia to healthy flowers.
If humidity remains high, germination will occur. The fungus grows through the style into the ovary of the developing berry. Infected berries turn white or salmon in color as other berries ripen. They shrivel, harden and fall to the ground prematurely. By spring they are pumpkin-shaped and a dark brown.