Spiraea japonica · Shrub
Powdery mildew: Improve air circulation by thinning dense growth and apply a fungicide if severe.
Honey fungus: Remove infected plants entirely to prevent spread to neighbouring vegetation.
Slugs and snails: Use physical barriers like copper tape or apply organic slug pellets around the base.
Aphids: Squash by hand or spray with a strong jet of water; use insecticidal soap if infestation persists.
Root rot: Ensure soil is well-drained and avoid overwatering; improve soil structure with grit if necessary.