Petroselinum crispum · Annual
Carrot fly: Use fine mesh netting as a physical barrier from April onwards and avoid planting near carrots.
Slugs and snails: Apply iron phosphate pellets or use beer traps and copper tape barriers to deter feeding.
Aphids: Squash colonies by hand or spray with a strong jet of water; introduce ladybirds for biological control.
Celery leaf miner: Remove and destroy heavily infested leaves immediately to break the life cycle.
Leaf spot: Improve air circulation, avoid wetting foliage when watering, and remove affected leaves.