Pest identification
What's eating my mountain cornflower?
Aphids
Signs: Dense colonies on young stems and flower buds cause distortion and copious sticky honeydew.
Control: Spray with insecticidal soap or neem oil; cut back after the first flush to remove infested growth and encourage fresh stems.
Slugs and snails
Signs: Young spring shoots and emerging foliage eaten; irregular holes and slime trails at the base.
Control: Apply iron phosphate pellets in early spring; use grit mulch around crowns.
Caterpillars
Signs: Holes in leaves and flower buds; frass on foliage, sometimes with silken webbing on bud heads.
Control: Hand-pick caterpillars; spray with Bacillus thuringiensis (Bt) if infestations are widespread.
Rabbits
Signs: Stems and leaves cleanly nibbled, often reducing plants to stumps before flowers emerge.
Control: Wire mesh cloches in spring protect emerging growth; interplanting with strongly aromatic plants may help deter rabbits.
Keep mountain cornflower pest-free
Healthy plants resist pests best. Get the basics right:
Mountain Cornflower pests — FAQ
What is eating my mountain cornflower?
Mountain Cornflower (Centaurea montana) is a vigorous perennial that can fall prey to aphids, leafhoppers, and caterpillars of the cornflower moth. Powdery mildew disfigures foliage in dry spells. Slugs attack young spring growth. Deer occasionally browse the foliage, but rabbits are a more consistent garden pest on this plant.
How do I get rid of aphids on mountain cornflower?
Dense colonies on young stems and flower buds cause distortion and copious sticky honeydew. Spray with insecticidal soap or neem oil; cut back after the first flush to remove infested growth and encourage fresh stems.
How do I get rid of slugs and snails on mountain cornflower?
Young spring shoots and emerging foliage eaten; irregular holes and slime trails at the base. Apply iron phosphate pellets in early spring; use grit mulch around crowns.
How do I get rid of caterpillars on mountain cornflower?
Holes in leaves and flower buds; frass on foliage, sometimes with silken webbing on bud heads. Hand-pick caterpillars; spray with Bacillus thuringiensis (Bt) if infestations are widespread.
How do I get rid of rabbits on mountain cornflower?
Stems and leaves cleanly nibbled, often reducing plants to stumps before flowers emerge. Wire mesh cloches in spring protect emerging growth; interplanting with strongly aromatic plants may help deter rabbits.