What's eating my watercress?

Watercress is most commonly damaged by flea beetles, which riddle leaves with tiny shot-holes, and by watercress leaf beetle (Phaedon cochleariae) larvae and adults. Cabbage white caterpillars, aphids, and slugs also attack plants. Deer and rabbits browse beds where accessible. The flea beetle is the most damaging pest.

Tiny round shot-holes scattered across leaves; seedlings can be killed; adults jump when disturbed; worst in warm, dry spells. Use fine insect mesh (enviromesh) over beds; keep plants well-watered and vigorous; apply diatomaceous earth around stems; yellow sticky traps to monitor adults.

Adults and larvae skeletonise leaves, leaving a lacework of veins; can cause serious crop loss in summer on commercial and garden beds. Hand-pick adults and larvae; remove affected foliage promptly; reflood beds if practical to dislodge larvae; pyrethrin spray as a last resort (check withdrawal periods for edible crop).

Large, irregular holes in leaves; green frass visible; caterpillars are camouflaged green and hide on leaf undersides. Check plants frequently and hand-pick eggs and larvae; apply Bacillus thuringiensis (Bt) spray; cover plants with fine mesh to exclude egg-laying butterflies.

Clusters on stem tips and leaf undersides causing curled, distorted new growth; honeydew encourages sooty mould on edible leaves. Knock off with water; use insecticidal soap; rinse harvested leaves thoroughly before eating; lady birds provide effective natural control.