Pink Spirea Flowers Browning: Fire Blight or Aphids?

Why Spirea Blooms Turn Brown After a Week

A gardener near the NJ shore has two pink spireas in partial afternoon shade (pine tree). Flowers brown quickly. Sandy soil.

Possible Causes

• Fire blight: Bacterial disease; flowers look burned, stems may have discolored wounds. Prune out infected wood, burn debris, treat with copper‑based fungicide.
• Aphids: Suck sap from flowers, causing browning. Blast off with strong water spray; use insecticidal soap.

Management

1. Remove spent blossoms promptly – may encourage a second flush.
2. Check stems for fire blight symptoms (shepherd’s crook, oozing cankers).
3. Improve air circulation; avoid overhead watering.

Shade Is Not the Issue

Partial shade reduces bloom quantity but doesn’t cause browning. The pine tree’s root competition may stress the shrubs, making them more susceptible.