Papaver
Aphids: Squash by hand or spray with a strong jet of water; use insecticidal soap if infestations are severe.
Powdery mildew: Improve air circulation and avoid overhead watering; treat with a fungicide if necessary.
Downy mildew: Remove affected foliage immediately and ensure good drainage to reduce humidity around the plant base.
Verticillium wilt: Remove and destroy infected plants; avoid replanting poppies or related species in the same soil.
Slugs and snails: Use physical barriers like copper tape or eggshells, or apply iron phosphate-based slug pellets.