Hypericum · Shrub
Rust: Remove affected leaves promptly and avoid excess nitrogen fertiliser to prevent soft growth.
Honey fungus: Ensure well-drained soil and remove infected plants entirely if identified.
Slugs and snails: Use physical barriers like copper tape or apply iron phosphate pellets around the base.
Vine weevil: Apply nematodes to the soil in autumn or use systemic insecticides for potted plants.
Powdery mildew: Improve air circulation and spray with a sulphur-based fungicide if severe.