Lobelia erinus L. · Annual
Slugs and snails: Standard UK slug and snail control — copper tape around baskets, hand-picking at night, ferric phosphate pellets, beer traps; do not let compost stay waterlogged. (RHS Pests: 'May be susceptible to slugs and snails'.)
Rust (Puccinia spp.): Improve air circulation, avoid overhead watering, remove and bin affected material. RHS Diseases note: 'Generally disease-free' — rust is occasional rather than routine.
Root and stem-base rots (Pythium / Rhizoctonia / Phytophthora group): Use free-draining container compost, water in the morning, avoid waterlogging, raise baskets so excess water can drain; replace affected plants and not the same compost. RHS Diseases note: 'Generally disease-free' — these are preventable rather than expected under UK cultivation.