Pests and Diseases of Lettuces

Lettuces

Aphids (various species)

Typical symptoms: Leaves are infested with pink or green aphids; the leaves may be sticky.

Prevention and treatment: See Aphids as Garden Pests

Cutworm (Noctua pronuba and other moth larvae)

Typical symptoms: Plants wilt suddenly; stems are eaten through at ground level. Large, fat caterpillars may be found in surrounding soil.

Prevention and treatment: See Pests and Diseases of Seedlings and Young Plants

Grey mould (Botrytis cinerea)

Typical symptoms: Heads of lettuce rot; a fluffy grey mould is present.

Prevention and treatment: See How to Treat Common Plant Diseases

Lettuce downy mildew (Bremia lactucae)

Typical symptoms: Yellow patches appear on leaves; white mould may develop underneath in damp conditions. The patches turn brown and angular with age.

Prevention and treatment: See How to Treat Common Plant Diseases

Lettuce root aphid (Pemphigus bursarius)

Typical symptoms: Plants wilt suddenly; growth may be stunted. Small, pale aphids are seen on the roots surrounded by a white powdery wax.

Prevention and treatment: The most effective way to avoid this pest is to grow resistant varieties. See Aphids as Garden Pests

Slugs and snails

Typical symptoms: Leaves are eaten at night; slime trails are visible.

Prevention and treatment: See Slugs and Snails – Garden Pest Control

Viruses and deficiencies

Typical symptoms: Yellow marbling or other unusual patterns on leaves.

Prevention and treatment: See Plant Diseases – Understanding the Problem

Wireworm (Agriotes lineatus)

Typical symptoms: Seedlings and larger plants grow poorly.

Prevention and treatment: See General Garden Pests