Aphids on lettuce
The glasshouse potato aphid and the currant-lettuce aphid gather in the heart of the rosette, where washing will not shift them. Besides the direct damage they transmit lettuce viruses.
Symptom photos
Symptoms
- Colonies of green or pinkish aphids in the heart of the rosette
- Aphids on leaf undersides along the veins
- Young leaves distorted and puckered
- Sticky honeydew and black sooty mold
- Mosaic discoloration of the leaves where virus is present
What it does to the crop
- Heads contaminated with aphids and unmarketable
- Transmission of lettuce mosaic virus
- Growth checked and the rosette deformed
- Poorer shelf life after cutting
What encourages it
- Warm, still weather from May onwards
- Growing under cover with no beneficial insects
- Too much nitrogen
- Weeds and currant bushes nearby where aphids overwinter
Prevention
- Cover the crop with fine insect mesh
- Check the heart of the rosette once a week
- Sow nectar plants for hoverflies and ladybirds
- Clear weeds from around the bed
- Keep nitrogen feeding moderate
⚠️ 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
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