🥬 Lettuce How hard it is to control: ★★★☆☆ 3/5

Slugs on lettuce

Slugs (the grey field slug and the Spanish slug) feed at night, chewing irregular holes in lettuce leaves. They do most damage to young transplants, which they can destroy in a single night.

Symptom photos

Slugs — Young plants with irregular holes chewed by slugs — Young plants with irregular holes chewed by slugs Photo: Downtowngal, licence CC BY-SA 3.0

Slugs — Spanish slug — adult slug, the cause of the damage — Spanish slug — adult slug, the cause of the damage Photo: Jin Zan, licence CC BY-SA 4.0

Symptoms

Irregular holes and chewed leaf edges
Silvery trails of dried slime on leaves and soil
Dark pellets of droppings on the leaves
Seedlings and young transplants eaten right down
The pests visible at dusk and after rain

What it does to the crop

Young transplants destroyed and gaps needing replanting
Unmarketable heads because of the damage and slime
Damage opening the way to bacterial rots
Gray mold spores carried from plant to plant

What encourages it

Damp, rainy weather and cool nights
Organic mulch and dense weeds providing shelter
Heavy, wet soils
A compost heap or scrub nearby

Prevention

Collect slugs in the evening and set beer traps
Keep paths narrow and clear of hiding places
Use barriers of ash, lime or copper tape around the bed
Water in the morning so the soil is dry by evening
Cultivate the soil deeply in autumn to destroy the eggs

⚠️ Before you reach for a spray

This atlas is informational and still growing — different diseases can look almost identical. Confirm the diagnosis and read the product label before applying any plant protection product. If you are unsure, ask your local extension or advisory service.

Keep the disease atlas with you in the garden

In the app you can identify a disease from photos, work out the spray dose for your own bed and log the treatment in your task calendar. Free, no sign-up, works offline.

Open the atlas in the app →

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