Garlic: Pests & Diseases
Garlic rewards a sunny, well-drained bed with a useful harvest of flavoursome bulbs. Autumn planting is common in much of the UK, although spring planting can suit colder or wetter gardens. Start with sound planting cloves and avoid repeating alliums in the same soil, particularly where white rot has appeared.
Common pests
Allium leaf miner is a key concern, with larvae tunnelling in leaves and brown pupae found in stems during spring and autumn. Onion fly maggots can attack young plants and bulbs. Leek moth may mine foliage, and thrips leave pale, silvery scars in dry weather. Stem and bulb eelworm causes twisted leaves, poor growth and distorted or soft cloves.
Common diseases
Onion white rot is the most serious garlic disease, producing yellowing plants, white fluffy growth and black sclerotia around the bulb. It can survive in soil for years. Downy mildew causes pale areas and greyish mould on foliage. Rust can make orange pustules on leaves. Basal and storage rots become more likely where bulbs are damaged, wet or insufficiently cured.
Prevention
Choose certified, healthy planting garlic and never plant suspicious cloves. Use a long allium rotation and do not move soil from beds affected by white rot. Plant at sensible spacing in free-draining ground for good airflow. Cover plants with fine mesh or fleece through allium leaf miner and onion fly flight periods. Remove crop debris, clean tools, and cure bulbs fully before storage.
Non-chemical control
Use securely edged mesh or fleece during spring and autumn to reduce allium leaf miner attacks, and keep it in place during onion fly activity. Remove severely mined, yellowing or rotting plants promptly and bin them rather than composting. Hand-pick pests where practical. Encourage ground beetles and insect-eating birds. For suspected eelworm, destroy affected plants and keep alliums out of that bed for several years.
What to look for
Inspect foliage weekly from early spring for pale leaf mines, brown pupae, curled growth and silvery thrips damage. Check for orange rust pustules and mildew after damp weather. As bulbs swell, investigate any yellowing plant by lifting it carefully. During curing and storage, remove bulbs showing softness, mould or rotting basal plates.
Tips
Avoid heavy feeding late in the season, which can encourage soft growth. Harvest once lower leaves have yellowed but before bulbs split. Dry bulbs in a covered, airy place, then store only firm, fully cured heads for the longest keeping quality.
Garlic pests & diseases: frequently asked questions
What are the common pests of garlic?
Allium leaf miner is a key concern, with larvae tunnelling in leaves and brown pupae found in stems during spring and autumn.
What diseases affect garlic?
Onion white rot is the most serious garlic disease, producing yellowing plants, white fluffy growth and black sclerotia around the bulb.
How do I prevent pests and diseases on garlic?
Choose certified, healthy planting garlic and never plant suspicious cloves.
General guidance for UK home gardens, focused on prevention and non-chemical control. The RHS or a local garden centre can help with tricky cases. Page updated 18 Sep 2026.