What's eating my thalictrum flavum subsp. glaucum?

Thalictrum flavum subsp. glaucum (glaucous yellow meadow rue) is pest-resistant and trouble-free in well-chosen sites. Slugs can attack the attractive blue-grey foliage when it first emerges in spring. Powdery mildew is an occasional late-summer problem, especially in dry conditions. Aphids cause only minor, transient damage on established plants.

Young glaucous leaves eaten or holed as they emerge; plants in moist, sheltered spots are most vulnerable in spring. Ferric phosphate pellets around emerging growth in spring. Sharp grit or wool-based barriers around crowns. Hand-collect on wet evenings; encourage ground beetles and hedgehogs.

White powdery patches on leaf surfaces during prolonged dry spells in late summer; causes premature leaf yellowing and drop. Maintain consistent soil moisture at the root zone. Thin surrounding planting to improve air circulation. Remove affected leaves; apply a diluted neem oil or bicarbonate spray to slow progression.

Occasional colonies on shoot tips; honeydew may attract ants but colonies rarely reach damaging levels. Blast off with water. Insecticidal soap if colonies persist. Avoid over-feeding with nitrogen-rich fertiliser, which encourages the soft growth aphids prefer.