Allium ursinum · Bulb
Onion white rot: Remove affected plants immediately and avoid replanting alliums in that soil for many years.
Downy mildew: Improve air circulation and remove infected foliage to reduce humidity around the plants.
Slugs and snails: Use beer traps or iron phosphate pellets to protect tender new growth in spring.
Vine weevil: Check roots for grubs when planting and apply biological nematodes if infestation is found.
Excessive spreading: Install root barriers or regularly dig up new bulbils to restrict expansion into unwanted areas.