Pest identification
What's eating my purple choy sum?
Cabbage aphid (Brevicoryne brassicae)
Signs: Grey-waxy colonies on flowering stems and leaf axils; harder to spot against purple foliage — inspect undersides carefully.
Control: Weekly underside inspections once bolting starts; insecticidal soap or pyrethrin spray; water jet; harvest stems before colonies establish.
Flea beetle (Phyllotreta spp.)
Signs: Small round holes through young leaf tissue; seedling leaves become tattered.
Control: Insect mesh from germination; keep plants well-irrigated for fast establishment.
Cabbage white caterpillar (Pieris rapae / Pieris brassicae)
Signs: Holes and chewed edges on leaves; frass in leaf folds.
Control: Exclusion netting; Btk biological spray; hand-pick eggs and caterpillars.
Slugs and snails
Signs: Ragged base leaf damage and slime trails; young plants most at risk.
Control: Iron phosphate pellets; beer traps; grit mulch; hand-pick at dusk.
Keep purple choy sum pest-free
Healthy plants resist pests best. Get the basics right:
Purple Choy Sum pests — FAQ
What is eating my purple choy sum?
Purple Choy Sum shares the brassica pest complex but the purple pigmentation can hide aphid colonies — look on leaf undersides and axils, not just the top surface. Flea beetles, caterpillars, and slugs also attack. Aphids on the tender flowering shoots are the most damaging pest, making the harvest unappealing if left unchecked.
How do I get rid of cabbage aphid (brevicoryne brassicae) on purple choy sum?
Grey-waxy colonies on flowering stems and leaf axils; harder to spot against purple foliage — inspect undersides carefully. Weekly underside inspections once bolting starts; insecticidal soap or pyrethrin spray; water jet; harvest stems before colonies establish.
How do I get rid of flea beetle (phyllotreta spp.) on purple choy sum?
Small round holes through young leaf tissue; seedling leaves become tattered. Insect mesh from germination; keep plants well-irrigated for fast establishment.
How do I get rid of cabbage white caterpillar (pieris rapae / pieris brassicae) on purple choy sum?
Holes and chewed edges on leaves; frass in leaf folds. Exclusion netting; Btk biological spray; hand-pick eggs and caterpillars.
How do I get rid of slugs and snails on purple choy sum?
Ragged base leaf damage and slime trails; young plants most at risk. Iron phosphate pellets; beer traps; grit mulch; hand-pick at dusk.