Delphinium · Perennial
Black blotch: Remove affected plant parts immediately and avoid saving seed from infected plants.
Powdery mildew: Ensure good air circulation and apply a suitable fungicide if infection is severe.
Slugs and snails: Protect new shoots with physical barriers or use slug pellets around the base of plants.
Delphinium moth caterpillars: Inspect plants regularly and hand-pick caterpillars as soon as they are spotted.