Symphyotrichum novae-angliae · Perennial
Slugs and snails: Use physical barriers like copper tape or organic pellets to protect young shoots.
Powdery mildew: Ensure good air circulation and water at the base to keep foliage dry.
Aphids: Squash by hand or spray with a strong jet of water; introduce ladybirds if severe.
Fusarium wilt: Remove affected plants immediately to prevent spread and avoid replanting in same spot.
Leaf and bud eelworms: Remove and burn infected plant parts; avoid planting asters in infested soil.